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1.  Revision Rates after Primary Hip and Knee Replacement in England between 2003 and 2006 
PLoS Medicine  2008;5(9):e179.
Background
Hip and knee replacement are some of the most frequently performed surgical procedures in the world. Resurfacing of the hip and unicondylar knee replacement are increasingly being used. There is relatively little evidence on their performance. To study performance of joint replacement in England, we investigated revision rates in the first 3 y after hip or knee replacement according to prosthesis type.
Methods and Findings
We linked records of the National Joint Registry for England and Wales and the Hospital Episode Statistics for patients with a primary hip or knee replacement in the National Health Service in England between April 2003 and September 2006. Hospital Episode Statistics records of succeeding admissions were used to identify revisions for any reason. 76,576 patients with a primary hip replacement and 80,697 with a primary knee replacement were included (51% of all primary hip and knee replacements done in the English National Health Service). In hip patients, 3-y revision rates were 0.9% (95% confidence interval [CI] 0.8%–1.1%) with cemented, 2.0% (1.7%–2.3%) with cementless, 1.5% (1.1%–2.0% CI) with “hybrid” prostheses, and 2.6% (2.1%–3.1%) with hip resurfacing (p < 0.0001). Revision rates after hip resurfacing were increased especially in women. In knee patients, 3-y revision rates were 1.4% (1.2%–1.5% CI) with cemented, 1.5% (1.1%–2.1% CI) with cementless, and 2.8% (1.8%–4.5% CI) with unicondylar prostheses (p < 0.0001). Revision rates after knee replacement strongly decreased with age.
Interpretation
Overall, about one in 75 patients needed a revision of their prosthesis within 3 y. On the basis of our data, consideration should be given to using hip resurfacing only in male patients and unicondylar knee replacement only in elderly patients.
Jan van der Meulen and colleagues show that about one in 75 patients with a primary hip or knee replacement needed a revision of their prosthesis within 3 years.
Editors' Summary
Background.
Though records show attempts to replace a hip date back to 1891, it was not till the 1960s before total hip replacements were successfully performed, and the 1970s before total knee replacements were carried out. These procedures are some of the most frequently performed surgical operations, with a total of 160,00 total hip and knee replacement procedures carried out in England and Wales and about half a million in the US in 2006. Hip and knee replacements are most commonly used as a treatment for severe arthritis once other approaches, such as pain relief medications, have failed. A total hip replacement involves replacing the head of the femur (the thigh bone) with an artificial component, typically metal; the socket into which the new femur head will insert is also replaced with artificial components. In an alternative procedure, resurfacing, rather than replacing the entire joint, the diseased surfaces are replaced with metal components. This procedure may be better suited to patients with less severe disease, and is also thought to result in quicker recovery. The techniques for hip and knee replacement can also be divided into those where a cement is used to position the metal implant into the bone (cemented) versus those where cement is not used (cementless).
Why Was This Study Done?
To date, little evidence has been available to compare patient outcomes following hip or knee replacement with the many different types of techniques and prostheses available. National registries have been established in a number of countries to try to collect data in order to build the evidence base for evaluating different types of prosthesis. Specifically, it is important to find out if there are any important differences in revision rates (how often the hip replacement has to be re-done) following surgery using the different techniques. In England and Wales, the National Joint Registry (NJR) has collected data on patient characteristics, types of prostheses implanted, and the type of surgical procedures used, since its initiation in April 2003.
What Did the Researchers Do and Find?
The researchers linked the records of the NJR and the Hospital Episode Statistics (HES) for patients treated by the NHS in England who had undergone a primary hip and knee replacement between April 2003 and September 2006. The HES database contains records of all admissions to NHS hospitals in England, and allowed the researchers to more accurately identify revisions of procedures that were done on patients in the NJR database.
They identified 327,557 primary hip or knee replacement procedures performed during that time period, but only 167,076 could be linked between the two databases.
76,576 patients in the linked database had undergone a primary hip replacement. The overall revision rate was 1.4% (95% confidence interval [CI] 1.2%–1.5%) at 3 years, with the lowest revision rates experienced by patients who had cemented prostheses. Women were found to have higher revision rates after hip resurfacing, and the revision rate was about twice as high in patients who had had a hip replacement for other indications than osteoarthritis. A patient's age did not appear to affect revision rates after hip surgery.
80,697 patients in the linked database had undergone a primary knee replacement. The overall revision rate was 1.4% (95% CI 1.3%–1.6%) at three years, again with the lowest rates of replacement experienced by patients who had cemented prostheses. Revision rates after knee replacement strongly decreased with age.
What Do These Findings Mean?
Overall, about one in 75 patients required a revision of their joint replacement, which is considered low, and cemented hip or knee prosthesis had the lowest revision rates. Post hip replacement, the highest revision rate was in patients who had undergone hip resurfacing, especially women. Following knee replacement, the highest revision rate was in patients who had undergone unicondylar prosthesis. However, in this study patients were only followed up for three years after the initial knee replacement, and it's possible that different patterns regarding the success of these differing techniques may emerge after longer follow-up. Importantly, this study was entirely observational, and data were collected from patients who had been managed according to routine clinical practice (rather than being randomly assigned to different procedures). Substantial differences in the age and clinical characteristics of patients receiving the different procedures were seen. As a result, it's not possible to directly draw conclusions on the relative benefits or harms of the different procedures, but this study provides important benchmark data with which to evaluate future performance of different procedures and types of implant.
Additional Information.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0050179.
The website of the British Orthopaedic Association contains information for patients and surgeons
The website of the National Institute for Health and Clinical Excellence contains guidance on hip prostheses
Information is available from the US National Institutes of Health (Medline) on hip replacement, including interactive tutorials and information about rehabilitation and recovery
Medline also provides similar resources for knee replacement
The NHS provides information for patients on hip and knee replacement, including questions patients might ask, real stories, and useful links
The National Joint Registry provides general information about joint replacement, as well as allowing users to download statistics on the data it has collected on the numbers of procedures carried out in the UK
doi:10.1371/journal.pmed.0050179
PMCID: PMC2528048  PMID: 18767900
2.  The migration pattern of the Charnley femoral stem: a five-year follow-up RSA study in a well-functioning patient group 
Background
Implant stability is considered vital to long-time implant survival in total hip arthroplasty (THA), since loose implants are reported to be a major cause of hip revision. There is an association between early implant micromotion and increased risk of revision. More implant-specific data are needed to establish acceptable levels of early implant movement.
Materials and methods
Thirty-five patients (36 hips) undergoing Charnley THA were followed with repeated clinical, radiographic, and radiostereometric analysis (RSA) over 5 years. Twenty-three patients attended 5 years postoperatively.
Results
The patient group was well functioning based on the radiological and clinical evaluations. The stems constantly moved up to 5 years postoperatively, with subsidence, retroversion, and varus tilt, based on the RSA.
Conclusion
Continuous movement of the Charnley stem was observed up to 5 years postoperatively in a well-functioning patient group. The migration data presented herein could be useful when defining acceptable migration limits for certain types of cemented femoral stems.
doi:10.1007/s10195-012-0187-x
PMCID: PMC3427697  PMID: 22576838
RSA; Charnley; THR; Five-year follow-up; Migration pattern
3.  Seven-year Results of a Tapered, Titanium, Hydroxyapatite-Coated Cementless Femoral Stem in Primary Total Hip Arthroplasty 
Clinics in Orthopedic Surgery  2010;2(4):214-220.
Background
Aseptic loosening of cemented hip prostheses is recognized as a long-term problem, and especially in males and younger patients. Much energy has been focused on developing new prostheses that are designed for cementless fixation. We evaluated the performance of and periprosthetic bone response to a tapered, titanium, hydroxyapatite (HA)-coated femoral hip prosthesis at a minimum of 7 years of follow-up after treatment with primary total hip arthroplasty.
Methods
Seventy-eight patients and 86 hips were included in the study. There were 35 men and 43 women; the mean age at the time of the operation was 59 years (range, 41 to 81 years). We used a tapered, titanium (Ti6Al4V), HA-coated femoral implant. We evaluated the patients at a minimum of 7 years of follow-up after treatment with primary total hip arthroplasty. Clinical evaluation was performed using the scoring system and the hip scores were assigned according to the level of pain, the functional status and the range of motion. The patients who refused to return, but who did forward X-rays for review after being contacted were questioned by phone about the functional status of their hip. Radiographic follow-up was performed at six weeks, at three, six and twelve months and yearly thereafter. All the available radiographs were collected and assessed for implant stability, subsidence, osseointegration, osteolysis, stress shielding and evidence of periprosthetic lucency.
Results
Eighty-six hips (78 patients) were available for review at follow-up of greater than 7 years. In 11 of the 86 cases, acetabular failure required revision of the acetabular component, but the femoral stem survived and it was available for long-term evaluation. The radiographs were obtained at 7-year follow-up for another 20 hips, but the patients would not come in for the 7-year clinical evaluation. Therefore, a phone interview was conducted to assess any change in the functional status at a minimum of 7 years.
Conclusions
The mechanical fixation of a tapered, titanium, HA-coated femoral implant was excellent in this study. This femoral design provided reliable osseointegration that was durable at a mean of 7 years follow-up.
doi:10.4055/cios.2010.2.4.214
PMCID: PMC2981777  PMID: 21119937
Primary total hip arthroplasty; Hydroxyapatite-coated femoral stem
4.  Metal-on-Metal Total Hip Resurfacing Arthroplasty 
Executive Summary
Objective
The objective of this review was to assess the safety and effectiveness of metal on metal (MOM) hip resurfacing arthroplasty for young patients compared with that of total hip replacement (THR) in the same population.
Clinical Need
Total hip replacement has proved to be very effective for late middle-aged and elderly patients with severe degenerative diseases of the hips. As indications for THR began to include younger patients and those with a more active life style, the longevity of the implant became a concern. Evidence suggests that these patients experience relatively higher rates of early implant failure and the need for revision. The Swedish hip registry, for example, has demonstrated a survival rate in excess of 80% at 20 years for those aged over 65 years, whereas this figure was 33% by 16 years in those aged under 55 years.
Hip resurfacing arthroplasty is a bone-conserving alternative to THR that restores normal joint biomechanics and load transfer. The technique has been used around the world for more than 10 years, specifically in the United Kingdom and other European countries.
The Technology
Metal-on-metal hip resurfacing arthroplasty is an alternative procedure to conventional THR in younger patients. Hip resurfacing arthroplasty is less invasive than THR and addresses the problem of preserving femoral bone stock at the initial operation. This means that future hip revisions are possible with THR if the initial MOM arthroplasty becomes less effective with time in these younger patients. The procedure involves the removal and replacement of the surface of the femoral head with a hollow metal hemisphere, which fits into a metal acetabular cup.
Hip resurfacing arthroplasty is a technically more demanding procedure than is conventional THR. In hip resurfacing, the femoral head is retained, which makes it much more difficult to access the acetabular cup. However, hip resurfacing arthroplasty has several advantages over a conventional THR with a small (28 mm) ball. First, the large femoral head reduces the chance of dislocation, so that rates of dislocation are less than those with conventional THR. Second, the range of motion with hip resurfacing arthroplasty is higher than that achieved with conventional THR.
A variety of MOM hip resurfacing implants are used in clinical practice. Six MOM hip resurfacing implants have been issued licences in Canada.
Review Strategy
A search of electronic bibliographies (OVID Medline, Medline In-Process and Other Non-Indexed Citations, Embase, Cochrane CENTRAL and DSR, INAHTA) was undertaken to identify evidence published from Jan 1, 1997 to October 27, 2005. The search was limited to English-language articles and human studies. The literature search yielded 245 citations. Of these, 11 met inclusion criteria (9 for effectiveness, 2 for safety).
The result of the only reported randomized controlled trial on MOM hip resurfacing arthroplasty could not be included in this assessment, because it used a cemented acetabular component, whereas in the new generation of implants, a cementless acetabular component is used. After omitting this publication, only case series remained.
Summary of Findings
 
Health Outcomes
The Harris hip score and SF-12 are 2 measures commonly used to report health outcomes in MOM hip resurfacing arthroplasty studies. Other scales used are the Oxford hip score and the University of California Los Angeles hip score.
The case series showed that the mean revision rate of MOM hip resurfacing arthroplasty is 1.5% and the incidence of femoral neck fracture is 0.67%. Across all studies, 2 cases of osteonecrosis were reported. Four studies reported improvement in Harris hip scores. However, only 1 study reported a statistically significant improvement. Three studies reported improvement in SF-12 scores, of which 2 reported a significant improvement. One study reported significant improvement in UCLA hip score. Two studies reported postoperative Oxford hip scores, but no preoperative values were reported.
None of the reviewed studies reported procedure-related deaths. Four studies reported implant survival rates ranging from 94.4% to 99.7% for a follow-up period of 2.8 to 3.5 years. Three studies reported on the range of motion. One reported improvement in all motions including flexion, extension, abduction-adduction, and rotation, and another reported improvement in flexion. Yet another reported improvement in range of motion for flexion abduction-adduction and rotation arc. However, the author reported a decrease in the range of motion in the arc of flexion in patients with Brooker class III or IV heterotopic bone (all patients were men).
Safety of Metal-on-Metal Hip Resurfacing Arthroplasty
There is a concern about metal wear debris and its systemic distribution throughout the body. Detectable metal concentrations in the serum and urine of patients with metal hip implants have been described as early as the 1970s, and this issue is still controversial after 35 years.
Several studies have reported high concentration of cobalt and chromium in serum and/or urine of the patients with metal hip implants. Potential toxicological effects of the elevated metal ions have heightened concerns about safety of MOM bearings. This is of particular concern in young and active patients in whom life expectancy after implantation is long.
Since 1997, 15 studies, including 1 randomized clinical trial, have reported high levels of metal ions after THR with metal implants. Some of these studies have reported higher metal levels in patients with loose implants.
Adverse Biological Effects of Cobalt and Chromium
Because patients who receive a MOM hip arthroplasty are shown to be exposed to high concentrations of metallic ions, the Medical Advisory Secretariat searched the literature for reports of adverse biological effects of cobalt and chromium. Cobalt and chromium make up the major part of the metal articulations; therefore, they are a focus of concern.
Risk of Cancer
To date, only one study has examined the incidence of cancer after MOM and polyethylene on metal total hip arthroplasties. The results were compared to that of general population in Finland. The mean duration of follow-up for MOM arthroplasty was 15.7 years; for polyethylene arthroplasty, it was 12.5 years. The standardized incidence ratio for all cancers in the MOM group was 0.95 (95% CI, 0.79–1.13). In the polyethylene on metal group it was 0.76 (95% CI, 0.68–0.86). The combined standardized incidence ratio for lymphoma and leukemia in the patients who had MOM THR was 1.59 (95% CI, 0.82–2.77). It was 0.59 (95% CI, 0.29–1.05) for the patients who had polyethylene on metal THR. Patients with MOM THR had a significantly higher risk of leukemia. All patients who had leukemia were aged over than 60 years.
Cobalt Cardiotoxicity
 
Epidemiological Studies of Myocardiopathy of Beer Drinkers
An unusual type of myocardiopathy, characterized by pericardial effusion, elevated hemoglobin concentrations, and congestive heart failure, occurred as an epidemic affecting 48 habitual beer drinkers in Quebec City between 1965 and 1966. This epidemic was directly related the consumption of a popular beer containing cobalt sulfate. The epidemic appeared 1 month after cobalt sulfate was added to the specific brewery, and no further cases were seen a month after this specific chemical was no longer used in making this beer. A beer of the same name is made in Montreal, and the only difference at that time was that the Quebec brand of beer contained about 10 times more cobalt sulphate. Cobalt has been added to some Canadian beers since 1965 to improve the stability of the foam but it has been added in larger breweries only to draught beer. However, in small breweries, such as those in Quebec City, separate batches were not brewed for bottle and draught beer; therefore, cobalt was added to all of the beer processed in this brewery.
In March 1966, a committee was appointed under the chairmanship of the Deputy Minister of Health for Quebec that included members of the department of forensic medicine of Quebec’s Ministry of Justice, epidemiologists, members of Food and Drug Directorate of Ottawa, toxicologists, biomedical researchers, pathologists, and members of provincial police. Epidemiological studies were carried out by the Provincial Ministry of Health and the Quebec City Health Department.
The association between the development of myocardiopathy and the consumption of the particular brand of beer was proven. The mortality rate of this epidemic was 46.1% and those who survived were desperately ill, and recovered only after a struggle for their lives.
Similar cases were seen in Omaha (Nebraska). The epidemic started after a cobalt additive was used in 1 of the beers marketed in Nebraska. Sixty-four patients with the clinical diagnosis of alcoholic myocardiopathy were seen during an 18-month period (1964–1965). Thirty of these patients died. The first patient became ill within 1 month after cobalt was added to the beer, and the last patient was seen within 1 month of withdrawal of cobalt.
A similar epidemic occurred in Minneapolis, Minnesota. Between 1964 and 1967, 42 patients with acute heart failure were admitted to a hospital in Minneapolis, Minnesota. Twenty of these patients were drinking 6 to 30 bottles per day of a particular brand of beer exclusively. The other 14 patients also drank the same brand of beer, but not exclusively. The mortality rate from the acute illness was 18%, but late deaths accounted for a total mortality rate of 43%. Examination of the tissue from these patients revealed markedly abnormal changes in myofibrils (heart muscles), mitochondria, and sarcoplasmic reticulum.
In Belgium, a similar epidemic was reported in 1966, in which, cobalt was used in some Belgian beers. There was a difference in mortality between the Canadian or American epidemic and this series. Only 1 of 24 patients died, 1.5 years after the diagnosis. In March 1965, at an international meeting in Brussels, a new heart disease in chronic beer drinkers was described. This disease consists of massive pericardial effusion, low cardiac output, raised venous pressure, and polycythemia in some cases. This syndrome was thought to be different from the 2 other forms of alcoholic heart disease (beriberi and a form characterized by myocardial fibrosis).
The mystery of the above epidemics as stated by investigators is that the amount of cobalt added to the beer was below the therapeutic doses used for anemia. For example, 24 pints of Quebec brand of beer in Quebec would contain 8 mg of cobalt chloride, whereas an intake of 50 to 100 mg of cobalt as an antianemic agent has been well tolerated. Thus, greater cobalt intake alone does not explain the occurrence of myocardiopathy. It seems that there are individual differences in cobalt toxicity. Other features, like subclinical alcoholic heart disease, deficient diet, and electrolyte imbalance could have been precipitating factors that made these patients susceptible to cobalt’s toxic effects.
In the Omaha epidemic, 60% of the patients had weight loss, anorexia, and occasional vomiting and diarrhea 2 to 6 months before the onset of cardiac symptoms. In the Quebec epidemic, patients lost their appetite 3 to 6 months before the diagnosis of myocardiopathy and developed nausea in the weeks before hospital admission. In the Belgium epidemic, anorexia was one of the most predominant symptoms at the time of diagnosis, and the quality and quantity of food intake was poor. Alcohol has been shown to increase the uptake of intracoronary injected cobalt by 47%. When cobalt enters the cells, calcium exits; this shifts the cobalt to calcium ratio. The increased uptake of cobalt in alcoholic patients may explain the high incidence of cardiomyopathies in beer drinkers’ epidemics.
As all of the above suggest, it may be that prior chronic exposure to alcohol and/or a nutritionally deficient diet may have a marked synergistic effect with the cardiotoxicity of cobalt.
Conclusions
MOM hip resurfacing arthroplasty has been shown to be an effective arthroplasty procedure as tested in younger patients.
However, evidence for effectiveness is based only on 7 case series with short duration of follow-up (2.8–3.5 years). There are no RCTs or other well-controlled studies that compare MOM hip resurfacing with THR.
Revision rates reported in the MOM studies using implants currently licensed in Canada (hybrid systems, uncemented acetabular, and cemented femoral) range from 0.3% to 3.6% for a mean follow-up ranging from 2.8 to 3.5 years.
Fracture of femoral neck is not very common; it occurs in 0.4% to 2.2% of cases (as observed in a short follow-up period).
All the studies that measured health outcomes have reported improvement in Harris Hip and SF-12 scores; 1 study reported significant reduction in pain and improvement in function, and 2 studies reported significant improvement in SF-12 scores. One study reported significant improvement in UCLA Hip scores.
Concerns remain on the potential adverse effects of metal ions. Longer-term follow-up data will help to resolve the inconsistency of findings on adverse effects, including toxicity and carcinogenicity.
Ontario-Based Economic Analysis
The device cost for MOM ranges from $4,300 to $6,000 (Cdn). Traditional hip replacement devices cost about $2,000 (Cdn). Using Ontario Case Costing Initiative data, the total estimated costs for hip resurfacing surgery including physician fees, device fees, follow-up consultation, and postsurgery rehabilitation is about $15,000 (Cdn).
Cost of Total Hip Replacement Surgery in Ontario
MOM hip arthroplasty is generally recommended for patients aged under 55 years because its bone-conserving advantage enables patients to “buy time” and hence helps THRs to last over the lifetime of the patient. In 2004/2005, 15.9% of patients who received THRs were aged 55 years and younger. It is estimated that there are from 600 to 1,000 annual MOM hip arthroplasty surgeries in Canada with an estimated 100 to 150 surgeries in Ontario. Given the increased public awareness of this device, it is forecasted that demand for MOM hip arthroplasty will steadily increase with a conservative estimate of demand rising to 1,400 cases by 2010 (Figure 10). The net budget impact over a 5-year period could be $500,000 to $4.7 million, mainly because of the increasing cost of the device.
Projected Number of Metal-on-Metal Hip Arthroplasty Surgeries in Ontario: to 2010
PMCID: PMC3379532  PMID: 23074495
5.  Custom stems for femoral deformity in patients less than 40 years of age 
Acta Orthopaedica  2009;80(4):420-425.
Background and purpose Femoral deformity associated with osteoarthritis is a challenge for both the surgeon and the implant. Many of the patients with these deformities are young. Standard implants can be difficult to fit into these femurs. We prospectively evaluated the outcome of custom uncemented femoral stems in young patients.
Methods 61 consecutive patients (72 hips) underwent surgery for osteoarthritis because of femoral deformity at a mean age of 35 (22–40) years. The patients received a CT3D-A custom-made femoral stem and an uncemented cup. The mean follow-up time was 14 (10–16) years. 2 patients died at 7 and 8 years after surgery, otherwise, none of the patients were lost to follow-up.
Results At follow-up, the femoral prosthesis had not been revised in 59 patients (70 hips). 3 patients (3 hips) had required revision surgery due to loosening of the acetabular component; 2 hips were awaiting revision surgery for loosening of the acetabular cup. There were no cases of dislocation or infection. At review, all stems were considered stable according to the radiographic criteria. No migration or subsidence was observed on plain radiographs.
Interpretation Our results are comparable to published results of custom stems regarding survival and outcome. Considering the young age and the deformities in this series of uncemented custom femoral stems, and the fact that there was follow-up of up to 16 years, the survival is remarkable. This technique appears to be a reasonable alternative in younger patients with femoral deformities.
doi:10.3109/17453670903062470
PMCID: PMC2823196  PMID: 19513891
6.  Five-year results of a cementless short-hip-stem prosthesis 
Orthopedic Reviews  2013;5(1):e4.
Hip prosthesis stems with a short stem length and proximal fixation geometry support a bone-preserving and muscle-sparing implantation and should also allow for revision surgery with a standard hip stem. We present 250 prospectively documented clinical and radiological results from the Metha Short Hip Stem prosthesis (B. Braun-Aesculap, Tuttlingen, Germany) after an average follow-up of 4.9 years. The average patient age at surgery was 60 years. Indication for total hip replacement was primary osteoarthrosis (OA) (78% of patients), OA based on developmental dysplasia of the hip (16%), and other indications (6%). At the last follow-up, the average Harris Hip Score was 97 points. 85% of patients were very satisfied and 14% were satisfied after surgery, whereas 1% were dissatisfied. Pain according to the Visual Analogue Scale improved from 7.4 (min 1.6, max 9.5) pre-operatively to 0.23 (min 0, max 6.6). No joint dislocations occurred when predominantly using 28 mm and 32 mm prosthesis heads. Nine short-stems were revised: three after bacterial infections, two after primary via valsa with penetration of the femoral cortex two and three months after surgery, and three after early aseptic cases of loosening within the first year. A further nine osseously consolidated short-stems had to be replaced due to breakage of the modular titanium cone adapter after an average of 3.1 years (min 1.9, max 4.4). All surgical revisions were performed using primary standard stems. Without taking the material-related adapter failures into account, a five year Kaplan-Meier survival rate of 96.7% (95% confidence interval 93.4–98.3) was determined for the short-stem prostheses. There were no radiological signs of loosening in any of the short-stem prostheses at the last examination. Fine sclerotic lines were detected in Gruen's AP zones 1 (19%) and 2 (10.5%), individual hypertrophies in zone 3 (3.5%), fine seams in zones 4 (5.5%) and 5 (4%), without pedestal formations in zone 4, clear cancellous bone compressions in zone 6 (97.5%), as well as single fine scleroses (1.5%) and atrophies (2.5%) in zone 7. The mid-term clinical results with periprosthetic bone remodeling and without radiological signs of loosening confirm this metaphyseal short-stem treatment and fixation concept and the possibility of revision surgery using standard hip stems. Long-term results must be further observed on a prospective basis as part of this collective study.
doi:10.4081/or.2013.e4
PMCID: PMC3662260  PMID: 23705062
short-stem hip prosthesis; prospective follow-up study; mid-term results.
7.  Low BMD affects initial stability and delays stem osseointegration in cementless total hip arthroplasty in women 
Acta Orthopaedica  2012;83(2):107-114.
Background and purpose
Immediate implant stability is a key factor for success in cementless total hip arthroplasty (THA). Low bone mineral density (BMD) and age-related geometric changes of the proximal femur may jeopardize initial stability and osseointegration. We compared migration of hydroxyapatite-coated femoral stems in women with or without low systemic BMD.
Patients and methods
61 female patients with hip osteoarthritis were treated with cementless THA with anatomically designed hydroxyapatite-coated femoral stems and ceramic-ceramic bearing surfaces (ABG-II). Of the 39 eligible patients between the ages of 41 and 78 years, 12 had normal systemic BMD and 27 had osteopenia or osteoporosis. According to the Dorr classification, 21 had type A bone and 18 had type B. Translational and rotational migration of the stems was evaluated with radiostereometric analysis (RSA) up to 2 years after surgery.
Results
Patients with low systemic BMD showed higher subsidence of the femoral stem during the first 3 months after surgery than did those with normal BMD (difference = 0.6, 95% CI: 0.1–1.1; p = 0.03). Low systemic BMD (odds ratio (OR) = 0.1, CI: 0.006–1.0; p = 0.02), low local hip BMD (OR = 0.3, CI: 0.1–0.7; p = 0.005) and ageing (OR = 1.1, CI: 1.0–1.2; p = 0.02) were risk factors for delayed translational stability. Ageing and low canal flare index were risk factors for delayed rotational stabilization (OR = 3, CI: 1.1–9; p = 0.04 and OR = 1.1, CI: 1.0–1.2; p = 0.02, respectively). Harris hip score and WOMAC score were similar in patients with normal systemic BMD and low systemic BMD.
Interpretation
Low BMD, changes in intraosseous dimensions of the proximal femur, and ageing adversely affected initial stability and delayed osseointegration of cementless stems in women.
doi:10.3109/17453674.2012.678798
PMCID: PMC3339522  PMID: 22489886
8.  Fixation of the fully hydroxyapatite-coated Corail stem implanted due to femoral neck fracture 
Acta Orthopaedica  2012;83(2):153-158.
Background
Today, dislocated femoral neck fractures are commonly treated with a cemented hip arthroplasty. However, cementing of the femoral component may lead to adverse effects and even death. Uncemented stems may lower these risks and hydroxyapatite (HA) coating may enhance integration, but prosthetic stability and clinical outcome in patients with osteoporotic bone have not been fully explored. We therefore studied fixation and clinical outcome in patients who had had a femoral neck fracture and who had received a fully HA-coated stem prosthesis.
Patients and methods
50 patients with a dislocated femoral neck fracture were operated with the fully HA-coated Corail total or hemiarthroplasty. 38 patients, mean age 81 (70–96) years, were followed for 24 months with conventional radiographs, RSA, DEXA, and for clinical outcome.
Results
31 of the 38 implants moved statistically significantly up to 3 months, mainly distally, mean 2.7 mm (max. 20 mm (SD 4.3)), and rotated into retroversion mean 3.3º (–1.8 to 17) (SD 4.3) and then appeared to stabilize. Distal stem migration was more pronounced if the stem was deemed to be too small. There was no correlation between BMD and stem migration. The migration did not result in any clinically adverse effects.
Interpretation
The fully hydroxyapatite-coated Corail stem migrates during the first 3 months, but clinical outcome appears to be good, without any adverse events.
doi:10.3109/17453674.2011.641107
PMCID: PMC3339529  PMID: 22112154
9.  Primary cemented total hip arthroplasty: 10 years follow-up 
Indian Journal of Orthopaedics  2010;44(3):283-288.
Background:
Primary cemented total hip arthroplasty is a procedure for non-traumatic and traumatic affections of the hip. Long term follow-up is required to assess the longevity of the implant and establish the procedure. Indo-Asian literature on long term result of total hip arthroplasty is sparse. We present a 10-year follow-up of our patients of primary cemented total hip arthroplasty.
Materials and Methods:
We operated 31 hips in 30 patients with primary cemented total hip arthroplasty. We followed the cases for a minimum period of 10 years with a mean follow-up period of 12.7 years. The mean age of the patients was 60.7 years (range 37–82 yrs) male to female ratio was 2:1. The clinical diagnoses included - avascular necrosis of femoral head (n=15), sero positive rheumatoid arthritis (n=5), seronegative spondylo-arthropathy (n=4), neglected femoral neck fractures (n=3), healed tubercular arthritis (n=2) and post traumatic osteoarthritis of hip (n=2). The prostheses used were cemented Charnley’s total hip (n=12) and cemented modular prosthesis (n=19). The results were assessed according to Harris hip score and radiographs taken at yearly intervals.
Results:
The mean follow-up is 12.7 yrs (range 11-16 yrs) Results in all operated patients showed marked improvement in Harris hip score from preoperative mean 29.2 to 79.9 at 10 years or more followup. However, the non-inflammatory group showed more sustained long term improvement as compared to the inflammatory group, as revealed by the Harris hip score. Mean blood loss was 450ml (±3.7 ml), mean transfusion rate was 1.2 units (±.3). The complications were hypotension (n=7), shortening >1.5 cm (n=9), superficial infection (n=2) and malposition of prosthesis (n=1).
Conclusion:
The needs of Indian Asian patients, vary from what is discussed in literature. The pain tolerance is greater than western population and financial constraints are high. Thus revision surgery among Indian-Asian patients is less compared to western yard sticks.
doi:10.4103/0019-5413.65152
PMCID: PMC2911928  PMID: 20697481
Total hip arthroplasty; cemented hip arthroplasty; Harris hip score
10.  Excessive distal migration of fiber-mesh coated femoral stems 
Acta Orthopaedica  2011;82(3):308-314.
Background
The surface texture, localization, and magnitude of the surface material applied to the femoral stem can facilitate bone ingrowth and influence the survival of total hip arthroplasties. Clinical and radiographic studies have shown superior bone ingrowth in proximally porous-coated stems with a diaphyseal grit-blasted surface in comparison to a smooth diaphyseal surface. Surface textures—especially porous surface material—have been suggested to have a sealing effect against migration of polyethylene debris along the implant-bone interface and to reduce the inflammatory response, leading to a prolonged implant survival.
Patients and methods
Between 2004 and 2006, we conducted a randomized, controlled trial (RCT) involving 50 patients with non-inflammatory arthritis. They received either a distally tapered, extended coated stem or a straight, proximally coated stem. During surgery, tantalum markers were inserted into the greater and lesser trochanter. Implant migration was evaluated at 3, 12, and 24 months postoperatively by radiostereometric analysis. The primary endpoint was stem migration 2 years after surgery.
Results
All femoral components in both groups showed pronounced distal translation, with the highest rate of translation occurring between 0 and 3 months. After 2 years, the mean distal translation was 2.67 (95% CI: –3.93 to –1.42) mm for the tapered, extended coated stem and 1.80 (–2.45 to –1.15) mm for the straight, proximally coated stem. Half of the tapered, extended coated stems and two-thirds of the straight, proximally coated stems had migrated more than 1 mm. No difference between the 2 stems could be seen with regard to translation or rotation at any time point. After 2 years, 2 hips have been reoperated due to mechanical loosening of the stem.
Interpretation
An excessive amount of migration of both stem types was seen 2 years postoperatively. It is of vital importance to follow this patient cohort since radiostereometric analysis is known to be predictive of late implant failure, especially in this study where pronounced early migration was observed. We recommend longer follow-up of both stem types.
doi:10.3109/17453674.2011.574562
PMCID: PMC3235308  PMID: 21504304
11.  Small and similar amounts of micromotion in an anatomical stem and a customized cementless femoral stem in regular-shaped femurs 
Acta Orthopaedica  2014;85(2):152-158.
Background and purpose
High primary stability is important for long-term survival of uncemented femoral stems. Different stem designs are currently in use. The ABG-I is a well-documented anatomical stem with a press-fit design. The Unique stem is designed for a tight customized fit to the cortical bone of the upper femur. This implant was initially developed for patients with abnormal anatomy, but the concept can also be used in patients with normal femoral anatomy. We present 5-year radiostereometric analysis (RSA) results from a randomized study comparing the ABG-I anatomical stem with the Unique femoral stem.
Patients and methods
100 hips with regular upper femur anatomy were randomized to either the ABG-I stem or the Unique femoral stem. RSA measurements were performed postoperatively and after 3, 6, 12, 24, and 60 months.
Results
RSA measurements from 80 hips were available for analysis at the 5-year follow-up. Small amounts of movement were observed for both stems, with no statistically significant differences between the 2 types.
Interpretation
No improvement in long-term stability was found from using a customized stem design. However, no patients with abnormal geometry of the upper femur were included in this study.
doi:10.3109/17453674.2014.899846
PMCID: PMC3967257  PMID: 24650024
12.  Mid-term results of 155 patients treated with a collum femoris preserving (CFP) short stem prosthesis 
International Orthopaedics  2010;35(5):655-660.
Short stem prostheses that preserve the femoral neck are becoming more and more popular. The CFP (collum femoris preserving) has been introduced especially for the treatment of younger patients. However, information about remodelling, complications and learning curve are thus far rare. We present a retrospective study of 155 patients (average age 59.3 ± 9.9 years) who underwent total hip replacement with the CFP prosthesis. Follow-up was obtained 74.3 ± 9.4 months postoperatively. The Harris hip score revealed excellent and good results in 96%. One stem had to be exchanged due to aseptic loosening revealing a survival rate of 99% and 100% for stem and cup, respectively. Radiological analysis showed typical patterns of remodelling with apearance of cortical thickening predominantly in the distal part of the prosthesis. Implant related revision rate was <1%, with further complication rate independent of the surgeon’s individual experience. With regard to outcome, survivorship and complication rate, the medium-term results of the CFP prosthesis are promising.
doi:10.1007/s00264-010-1020-x
PMCID: PMC3080504  PMID: 20437260
13.  Stable fixation of an osseointegated implant system for above-the-knee amputees 
Acta Orthopaedica  2012;83(2):121-128.
Background and purpose
Rehabilitation of patients with transfemoral amputations is particularly difficult due to problems in using standard socket prostheses. We wanted to assess long-term fixation of the osseointegrated implant system (OPRA) using radiostereometric analysis (RSA) and periprosthetic bone remodeling.
Methods
51 patients with transfemoral amputations (55 implants) were enrolled in an RSA study. RSA and plain radiographs were scheduled at 6 months and at 1, 2, 5, 7, and 10 years after surgery. RSA films were analyzed using UmRSA software. Plain radiographs were graded for bone resorption, cancellization, cortical thinning, and trabecular streaming or buttressing in specifically defined zones around the implant.
Results
At 5 years, the median (SE) migration of the implant was –0.02 (0.06) mm distally. The rotational movement was 0.42 (0.32) degrees around the longitudinal axis. There was no statistically significant difference in median rotation or migration at any follow-up time. Cancellization of the cortex (plain radiographic grading) appeared in at least 1 zone in over half of the patients at 2 years. However, the prevalence of cancellization had decreased by the 5-year follow-up.
Interpretation
The RSA analysis for the OPRA system indicated stable fixation of the implant. The periprosthetic bone remodeling showed similarities with changes seen around uncemented hip stems. The OPRA system is a new and promising approach for addressing the challenges faced by patients with transfemoral amputations.
doi:10.3109/17453674.2012.678799
PMCID: PMC3339524  PMID: 22489885
14.  A prospective cohort study on the short collum femoris-preserving (CFP) stem using RSA and DXA 
Acta Orthopaedica  2013;84(1):32-39.
Background and purpose
Short femoral stems have been introduced in total hip arthroplasty in order to save proximal bone stock. We hypothesized that a short stem preserves periprosthetic bone mineral density (BMD) and provides good primary stability.
Methods
We carried out a prospective cohort study of 30 patients receiving the collum femoris-preserving (CFP) stem. Preoperative total hip BMD and postoperative periprosthetic BMD in Gruen zones 1–7 were investigated by dual-energy x-ray absorptiometry (DXA), stem migration was analyzed by radiostereometric analysis (RSA), and the Harris hip score (HHS) was determined.
Results
2 patients were excluded intraoperatively and 1 patient was revised due to a deep infection, leaving 27 patients for analysis. The mean HHS increased from 49 (24–79) preoperatively to 99 (92–100) after 2 years. DXA after 1 year showed substantial loss of BMD in Gruen zone 7 (–31%), zone 6 (–19%), and zone 2 (–13%, p < 0.001) compared to baseline BMD determined immediately postoperatively. The bone loss in these regions did not recover after 2 years, whereas the more moderate bone loss in Gruen zones 1, 3, and 5 partially recovered. There was a correlation between low preoperative total hip BMD and a higher amount of bone loss in Gruen zones 2, 6 and 7. RSA showed minor micromotion of the stem: mean subsidence was 0.13 (95% CI: –0.28 to 0.01) mm and mean rotation around the longitudinal axis was 0.01º (95% CI: –0.1 to 0.39) after 2 years.
Interpretation
We conclude that substantial loss in proximal periprosthetic BMD cannot be prevented by the use of a novel type of short, curved stem, and forces appear to be transmitted distally. However, the stems showed very small migration—a characteristic of stable uncemented implants.
doi:10.3109/17453674.2013.765623
PMCID: PMC3584599  PMID: 23343375
15.  Stress shielding effects of two prosthetic groups after total hip joint simulation replacement 
Objective
The study aims to compare the stress shielding effects of implantable anatomical and traditional prostheses after in vitro total hip joint replacement simulation. The study serves as a biomechanical basis for novel artificial prostheses and for clinical hip joint replacements.
Methods
Sixteen femoral specimens from adult male corpses were randomly divided into two groups: the traditional prosthesis group implanted into femur specimens using simulated total hip joint replacement (n = 8) and the femoral neck-preserved anatomical prosthesis implantation group that used a collum femoris preserving stem/trabeculae oriented pattern (CFP/TOP) acetabular cup (n = 8). The strain values in the two groups before and after prosthesis implantation were measured at different test points using electric resistance strain gauges. The stress shielding rate was calculated according to the related formula.
Results
The results showed that the rates of proximal femoral stress shielding were significantly higher at test points 1–10 in the traditional femoral prosthesis transplantation group than in the anatomical prosthesis group (p < 0.05).
Conclusions
There were different effects of stress shielding between the anatomical and traditional prostheses. Retained femoral anatomical implants should reduce stress shielding and increase the stability of anatomical prosthesis implants.
doi:10.1186/s13018-014-0071-x
PMCID: PMC4237889  PMID: 25174846
Hip joint; Artificial prosthesis; Replacement; Electric measurement
16.  Equally good fixation of cemented and uncemented cups in total trapeziometacarpal joint prostheses 
Acta Orthopaedica  2013;84(1):98-105.
Background and purpose
Cup failure is a recognized problem in total trapeziometacarpal (TM) joint prostheses; it may be related to poor fixation, which can be revealed by radiostereometric analysis (RSA). We compared the early implant migration of cemented trapezium cups to that of uncemented screw cups.
Patients and methods
In a prospective, parallel-group, randomized patient-blinded clinical trial, we included 32 hands in 28 patients (5 males) with a mean age of 58 (40–77) years and with Eaton stage-2 or -3 osteoarthritis of the trapeziometacarpal joint. Patients were randomized to surgery with a cemented DLC all-polyethylene cup (C) (n = 16) or an uncemented hydroxyapatite-coated chrome-cobalt Elektra screw cup (UC) (n = 16). Uncemented cups were inserted without threading of the bone. Stereoradiographs for evaluation of cup migration (primary effect size) and DASH and pain scores were obtained during 2 years of follow-up.
Results
The 2-year total translation (TT) was similar (p = 0.2): 0.24 mm (SD 0.10) for the C (n = 11) and 0.19 mm (SD 0.16) for the UC (n = 11). Variances were similar (p = 0.4). Judged by RSA, 2 UC cups and 1 C cup became loose (TT > 1 mm). Both UC cups were found to be loose at revision. Grip strength, pain, and DASH scores were similar between groups at all measurement points.
Interpretation
Early implant fixation and clinical outcome were equally good with both cup designs. This is the first clinical RSA study on trapezium cups, and the method appears to be clinically useful for detection of loose implants.
doi:10.3109/17453674.2013.765625
PMCID: PMC3584612  PMID: 23343372
17.  Clinical Results and Failure Mechanisms of a Nonmodular Constrained Knee Without Stem Extensions 
HSS Journal  2012;8(2):96-102.
Introduction
In the setting of persistent knee instability despite appropriate ligament balancing for primary total knee arthroplasty, most surgeons advocate the use of an implant with increased articular constraint. These implants are commonly supplemented with stem extensions to improve stress transfer and decrease the risk of aseptic loosening. However, disadvantages exist with the use of stem extensions, including increased cost, intramedullary invasion, and diaphyseal pain. The objectives of this study were to (1) compare the clinical results as assessed by the Knee Society, Hospital for Special Surgery, and SF-12 scores, (2) determine the incidence of failure as defined by the need for a revision procedure, and (3) to analyze the causes or modes of failure of a nonmodular constrained condylar knee without the use of stem extensions versus a conventional, posterior-stabilized design.
Materials and Methods
From 2002 to 2007, 190 TKAs were implanted using a primary, nonmodular constrained (NMC) prosthesis without stem extensions. During the same time period, clinical data were available for 140 TKAs implanted using a standard, posterior-stabilized (PS) design. Preoperative demographic data was reviewed, in addition to the rate and reason for revision in each cohort. Clinical data included HSS, Knee Society, and SF-12 scores at the latest follow-up, and the results of the NMC and PS cohorts were statistically compared using a Student’s two-tailed t test.
Results
The mean age of patients in the NMC cohort was 72.3 ± 10.2 years, and the mean length of follow-up was 7.3 ± 2.1 years. The mean age of the PS cohort was 67.1 ± 8.7 years, with a mean follow-up of 6.1 ± 2.2 years. No statistically significant differences in the HSS, Knee Society, or SF-12 scores were appreciated between the two cohorts. The revision rate in the NMC cohort was 4.2 % compared to 4.3 % for the PS cohort. The most common cause of failure in the NMC cohort was femoral component loosening, all of which occurred when Palacos cement was used for fixation. NMC components (55.6 %) implanted with Palacos cement failed due to femoral component loosening. In contrast, all PS components requiring revision were revised for persistent instability.
Discussion
At mid-term follow-up, NMC prostheses without stem extensions have excellent clinical results and are a viable option for patients with ligamentous instability. The use of Palacos cement in this scenario was associated with a high rate of femoral component loosening, possibly due to the decreased intrusion depth of Palacos when compared to Simplex cement.
doi:10.1007/s11420-012-9277-9
PMCID: PMC3715634  PMID: 23874246
nonmodular; constrained total condylar knee; component loosening; Palacos cement
18.  Painful Knee Prosthesis: Surgical Approach 
A painful knee prosthesis is, unfortunately, a condition whose possible causes are not always easily diagnosed. As a consequence, it can be difficult to resolve.
Common causes of prosthetic failure, such as aseptic loosening, infection, instability, progressive patellar arthropathy and recurrent synovitis are associated with clearly defined radiographic and/or clinical evidence.
Blood chemistry tests for indicators of infection and synovial fluid culture are always to be considered of primary importance in the diagnostic work up of a painful prosthesis, given that, in this situation, prosthetic infection should always be considered first, and remain a possibility until some other causes has been demonstrated.
In the presence of an infected prosthesis we carry out a two-step revision, first using an articulating antibiotic-impregnated cement spacer with two mono-compartment components to preserve the range of movement; subsequently, after the infection has been resolved, we carry out new prosthetic surgery, generally using prostheses of increasing stability and bone grafts, depending on the residual bone stock.
Aseptic loosening of a knee prosthesis is a complication that is easily identified radiographically due to the presence of lines of radiolucency at the bone/prosthesis interface, associated with migration or angulation of the components. In these cases, it is necessary to revise the prosthesis, increasing its stability with diaphyseal shafts. With regard to this problem, we have, recently, also been evaluating the opportuneness and efficacy of pre- and post-operative treatment with bone-forming agents in patients with poor bone quality, in order to reduce the risk of loosening and extend the life of the prosthesis.
Varus-valgus, anteroposterior, global patellofemoral instability are failures, often due to technical errors, that can be diagnosed through clinical examination. In the presence of a painful prosthesis associated with frank instability, we perform revision using superstabilised or constrained implants, depending on the particular case.
Nevertheless, the diagnosis and treatment of a painful knee prosthesis can be extremely difficult if there is no clear evidence of any of the most common causes of failure.
In the presence of prosthetic components having large diaphyseal shafts, a sharp pain can be detected; in these situations, it is sometimes possible to observe, on radiographic examinations, effects of periprosthetic stress shielding. To resolve the problem the component would have to be replaced with one having a shaft with a smaller diameter.
A painful prosthesis accompanied by a patellar clunk can be attributed to the formation of a subquadricipital fibrous nodule proximal to the patella which can be responsable of impingement with the anterior margin of the posterior-stabilising femoral component box. Arthroscopic removal of the fibrous nodule will, in this case, resolve the pain.
Recurrent synovitis can also be effectively treated arthroscopically.
If pain is of patellofemoral origin, it is necessary, in the case of a prosthetic patella, to evaluate the stability of the component and any alterations in its motion. As far as the surgical technique is concerned, in cases in which patellar lateralisation is performed, medialising the button so as to obtain improved tracking, we recommend not using too small a patellar component and performing an oblique osteotomy laterally to the button in order to reduce the risk of pain due to non-lined patella/femoral component interference. In the presence of a natural patella progressive arthropathy can often cause late-onset knee pain at anterior patellar level; in this case, prosthetic patella insertion is needed with, in the event of altered tracking, lateral release.
In some cases patellofemoral pain is related to misalignment of the components, which can be evaluated precisely through the superimposition of references in CT images. In this situation it is essential to perform a revision of the prosthesis, seeking to obtain the correct rotations and correct mechanical axis alignment.
Another possible aetiological factor in painful knee prosthesis is allergy to metals, in particular to nickel. Diagnosis of metal allergy, but above all its role in the pain, is currently much debated. Therefore, before carrying out the revision procedure, it is worth excluding all other possible causes and ascertaining, beyond doubt, the degree of the allergy itself. Diagnosis by means of a skin patch test does not currently seem to be of undisputed diagnostic value; in our practice, we effect diagnoses on the basis of blood tests, looking carefully for specific cytokines and activated cell lines with thymidine labelling and confocal microscopy. Laboratory diagnostic work up of patients identified on the basis of history makes it possible to avoid failures due to sensitivity to metals. In the event of allergy-related failure, the quantity of nickel in the revision prosthesis must be minimal.
PMCID: PMC3213830
19.  Good stability but high periprosthetic bone mineral loss and late-occurring periprosthetic fractures with use of uncemented tapered femoral stems in patients with a femoral neck fracture 
Acta Orthopaedica  2014;85(4):396-402.
Background and purpose
We previously evaluated a new uncemented femoral stem designed for elderly patients with a femoral neck fracture and found stable implant fixation and good clinical results up to 2 years postoperatively, despite substantial periprosthetic bone mineral loss. We now present the medium-term follow-up results from this study.
Patients and methods
In this observational prospective cohort study, we included 50 patients (mean age 81 (70–92) years) with a femoral neck fracture. All patients underwent surgery with a cemented cup and an uncemented stem specifically designed for fracture treatment. Outcome variables were migration of the stem measured with radiostereometry (RSA) and periprosthetic change in bone mineral density (BMD), measured with dual-energy X-ray absorptiometry (DXA). Hip function and health-related quality of life were assessed using the Harris hip score (HHS) and the EuroQol-5D (EQ-5D). DXA and RSA data were collected at regular intervals up to 4 years, and data concerning reoperations and hip-related complications were collected during a mean follow-up time of 5 (0.2–7.5) years.
Results
At 5 years, 19 patients had either passed away or were unavailable for further participation and 31 could be followed up. Of the original 50 patients, 6 patients had suffered a periprosthetic fracture, all of them sustained after the 2-year follow-up. In 19 patients, we obtained complete RSA and DXA data and no component had migrated after the 2-year follow-up. We also found a continuous total periprosthetic bone loss amounting to a median of –19% (–39 to 2). No changes in HHS or EQ-5D were observed during the follow-up period.
Interpretation
In this medium-term follow-up, the stem remained firmly fixed in bone despite considerable periprosthetic bone mineral loss. However, this bone loss might explain the high number of late-occurring periprosthetic fractures. Based on these results, we would not recommend uncemented femoral stems for the treatment of femoral neck fractures in the elderly.
doi:10.3109/17453674.2014.931195
PMCID: PMC4105771  PMID: 24954490
20.  Impaction grafting in the femur in cementless modular revision total hip arthroplasty: a descriptive outcome analysis of 243 cases with the MRP-TITAN revision implant 
Background
We present a descriptive and retrospective analysis of revision total hip arthroplasties (THA) using the MRP-TITAN stem (Peter Brehm, Weisendorf, GER) with distal diaphyseal fixation and metaphyseal defect augmentation. Our hypothesis was that the metaphyseal defect augmentation (Impaction Bone Grafting) improves the stem survival.
Methods
We retrospectively analyzed the aggregated and anonymized data of 243 femoral stem revisions. 68 patients with 70 implants (28.8%) received an allograft augmentation for metaphyseal defects; 165 patients with 173 implants (71.2%) did not, and served as controls. The mean follow-up was 4.4 ± 1.8 years (range, 2.1–9.6 years). There were no significant differences (p > 0.05) between the study and control group regarding age, body mass index (BMI), femoral defects (types I-III as described by Paprosky), and preoperative Harris Hip Score (HHS). Postoperative clinical function was evaluated using the HHS. Postoperative radiologic examination evaluated implant stability, axial implant migration, signs of implant loosening, periprosthetic radiolucencies, as well as bone regeneration and resorption.
Results
There were comparable rates of intraoperative and postoperative complications in the study and control groups (p > 0.05). Clinical function, expressed as the increase in the postoperative HHS over the preoperative score, showed significantly greater improvement in the group with Impaction Bone Grafting (35.6 ± 14.3 vs. 30.8 ± 15.8; p ≤ 0.05). The study group showed better outcome especially for larger defects (types II C and III as described by Paprosky) and stem diameters ≥ 17 mm. The two groups did not show significant differences in the rate of aseptic loosening (1.4% vs. 2.9%) and the rate of revisions (8.6% vs. 11%). The Kaplan-Meier survival for the MRP-TITAN stem in both groups together was 93.8% after 8.8 years. [Study group 95.7% after 8.54 years ; control group 93.1% after 8.7 years]. Radiologic evaluation showed no significant change in axial implant migration (4.3% vs. 9.3%; p = 0.19) but a significant reduction in proximal stress shielding (5.7% vs. 17.9%; p < 0.05) in the study group. Periprosthetic radiolucencies were detected in 5.7% of the study group and in 9.8% of the control group (p = 0.30). Radiolucencies in the proximal zones 1 and 7 according to Gruen occurred significantly more often in the control group without allograft augmentation (p ≤ 0.05).
Conclusion
We present the largest analysis of the impaction grafting technique in combination with cementless distal diaphyseal stem fixation published so far. Our data provides initial evidence of improved bone regeneration after graft augmentation of metaphyseal bone defects. The data suggests that proximal metaphyseal graft augmentation is beneficial for large metaphyseal bone defects (Paprosky types IIC and III) and stem diameters of 17 mm and above. Due to the limitations of a retrospective and descriptive study the level of evidence remains low and prospective trials should be conducted.
doi:10.1186/1471-2474-14-19
PMCID: PMC3556053  PMID: 23311769
Arthroplasty; Hip; Revision; Modular; Impaction bone grafting
21.  Total Knee Replacement 
Executive Summary
Objective
The aim of this review was to assess the effectiveness, in terms of pain reduction and functional improvement, and costing of total knee replacement (TKR) for people with osteoarthritis for whom less invasive treatments (such as physiotherapy, analgesics, anti-inflammatory drugs, intra-articular steroids, hyaluronic acids, and arthroscopic surgery) have failed.
Clinical Need
Osteoarthritis affects an estimated 10% to 12% of Canadian adults. The therapeutic goals of osteoarthritis treatment are to improve joint mobility and reduce pain. Stepwise treatment options include exercise, weight loss, physiotherapy, analgesics, anti-inflammatory drugs, intra-articular steroids and hyaluronic acids, arthroscopic surgery, and, in severe cases, total joint replacement with follow-up rehabilitation. These treatments are delivered by a range of health care professionals, including physiotherapists, occupational therapists, family physicians, internists, rheumatologists, and orthopedic surgeons. TKR is an end-of-line treatment for patients with severe pain and functional limitations. More women than men undergo knee replacement, and most patients are between 55 and 84 years old.
The Technology
TKR is a surgical procedure in which an artificial joint or prosthesis replaces a damaged knee joint. The primary indication for TKR is pain, followed by functional limitation. Usually, a person’s daily activities must be substantially affected by pain and functional limitations for him or her to be considered a candidate for TKR.
There are 3 different types of knee replacement prostheses. Non-constrained prostheses use the patient’s ligaments and muscles to provide the stability for the prosthesis. Semi-constrained prostheses provide some stability for the knee and do not rely entirely on the patient’s ligaments and muscles to provide the stability. Constrained prostheses are for patients whose ligaments and muscles are not able to provide stability for the knee prosthesis.
The most common risks and complications associated with TKR are deep venous thrombosis, infection, stiffness, loosening, and osteolysis. To prevent deep venous thrombosis, patients are treated with heparin prophylactically and/or given support stockings to wear. Patients are also given antibiotics for 24 hours after surgery to minimize the risk of infection. Stiffness is another associated complication. In most patients, it can be avoided by keeping the knee moving in the days and weeks following surgery.
The National Institutes of Health in the United States concluded that the indications for TKR should include the following: radiological evidence of joint damage, moderate to severe persistent pain that is not adequately relieved by nonsurgical management, and clinically significant functional limitation resulting in diminished quality of life.
Review Strategy
In March 2005, the following databases were searched: Cochrane Library International Agency for Health Technology Assessment (first quarter 2005), Cochrane Database of Systematic Reviews (first quarter 2005), Cochrane Central Register of Controlled Trials (first quarter 2005), MEDLINE (1966 to March 2005), MEDLINE In-Process and Other Non-indexed Citations (1966 to March 14, 2005), and EMBASE (1980 to 2005 week 9). The Medical Advisory Secretariat also searched Medscape on the Internet for recent reports on trials that were unpublished but that were presented at international conferences. In addition, the Web site Current Controlled Trials (www.controlled-trials.com) was searched for ongoing trials investigating TKR or unicompartmental knee replacement.
No studies were identified that compared TKR to an alternative treatment. Several studies have been reported that compare preoperative measurement scores on targeted measures of functioning and pain to postoperative measurement scores in patients undergoing various TKR procedures.
In order for the Medical Advisory Secretariat to measure the effectiveness of TKR and to compare the effectiveness of TKR across studies, effect sizes were calculated in studies that reported the standard deviations of the preoperative and postoperative measurement scores. Percent change was also calculated. For this review, a 20% improvement in outcome score was defined as the minimal clinically important difference.
Summary of Findings
Overall, patients who undergo TKR surgery for osteoarthritis have substantial improvements in terms of reduction of pain and improvement of function. A comparison of the mean effect score and the percent change in 19 studies that reported preoperative and postoperative outcome scores for patients who had TKR showed that the procedure is effective. The 19 studies included patients of various ages and used a variety of prostheses and techniques to implant the device. TKR was effective in all of the studies. The revision rates ranged from 0% to 13% in the studies that reported at least 5 years of follow-up.
As for the factors that predict TKR outcomes, a variety of factors have been evaluated, including obesity, age, gender, prosthesis design, and surgical techniques; however, none of these have been shown to predict outcomes (pain or function) consistently across studies. However, the regression analyses identified accounted for only 12% to 27% of the variance, indicating that over 70% of the variance in the outcomes of TKR is unexplained.
In terms of the timing of TKR surgery, 2 studies found that the severity of osteoarthritis does not predict outcome, but 1 study was found that higher functioning patients had significantly less pain and better function up to 2 years after surgery compared with lower functioning patients. It is important to note that the patients in the low and high function groups were evenly matched on comorbid conditions.
Unicompartmental knee replacement surgery seems to be as effective as TKR surgery for people who meet the indications for it. This is a subset of people who have osteoarthritis of the knee, because for unicompartmental knee replacement to be indicated, only 1 (usually the medial) compartment of the knee can be affected. Patients who undergo this kind of surgery seem to have shorter hospital stays and faster recovery times than do patients who have TKR surgery.
Conclusion
There is substantial evidence to indicate that TKR effectively reduces pain and improves function.
PMCID: PMC3382388  PMID: 23074478
22.  Head Material Influences Survival of a Cemented Total Hip Prosthesis in the Norwegian Arthroplasty Register 
Background
High prosthesis survival is reported for total hip prostheses with metal and alumina heads, but direct comparisons of a single prosthesis design with one of two different head materials has seldom been studied. Prostheses with zirconia heads are less commonly used than metal and alumina heads, and the few reports suggest variable results with zirconia heads.
Questions/Purposes
We therefore asked: (1) Would metal heads provide better survival of a cemented total hip arthroplasty (THA) than alumina heads? (2) Would metal heads provide better survival of a cemented THA than zirconia heads?
Methods
We searched in the Norwegian Arthroplasty Register for cemented primary THA cup/stem combinations that simultaneously had been used with different head materials. The only THA that fulfilled these inclusion criteria was the cemented Reflection All-Poly/Spectron EF (cup/stem) that had during 2001 to 2006 been used both with alumina (n = 448) and cobalt-chromium (n = 5229) heads; that implant had also been used with zirconia (n = 275) and cobalt-chromium heads (n = 3195) during 1997 to 2003, and we included patients with this THA from these two time intervals in the study. All cups were conventional polyethylene. We estimated prosthesis survival and relative revision risks adjusting for age, sex, and diagnosis. The followup in the two study materials was until December 2010.
Results
The survival at 8 years of the Spectron EF/Reflection THAs, inserted with alumina and cobalt-chromium heads during 2001 to 2006, was 92.3% and 94.0%, respectively. The Reflection/Spectron EF THA had inferior survival with zirconia heads compared with cobalt-chromium heads (relative risk, 1.7). At 12 years, the survival rate was 88.1% with cobalt-chromium heads and 74.8% with zirconia heads.
Conclusions
Alumina femoral heads provided no advantage over cobalt-chromium heads on midterm prosthesis survival. THAs with zirconia heads had inferior survival.
Level of Evidence
Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-012-2396-2
PMCID: PMC3462857  PMID: 22644422
23.  Eleven Year Results of Total Hip Arthroplasty in Patients with Secondary Osteoarthritis Due to Slipped Capital Femoral Epiphysis 
Background:
Total hip arthroplasty (THA) in patients with a history of Slipped Capital Femoral Epiphysis (SCFE), is typically indicated to address the consequent deformity of the proximal femur and/or acetabulum. It can be a challenging procedure for the orthopaedic surgeon. Previous studies have focused on prevention of osteoarthritis post-SCFE. However, there is a paucity of data on the outcomes of total hip arthroplasty in patients with osteoarthritis secondary to SCFE. This study was performed to assess the mid-term results of total hip arthroplasty in this patient cohort.
Materials and Methods:
All patients with secondary osteoarthritis due to slipped capital femoral epiphysis, treated with total hip arthroplasty between 1987 and 2005, were included in this retrospective study (n=30). Thirty patients (17 male, 13 female) met the inclusion criteria with one patient lost to follow-up and one unrelated death one year before follow up examination, thereby leaving 28 patients (32 hips) eligible for the study with a mean follow-up time period of 11.2 years. The Harris Hip Score (HHS) and MOS 36 short form health survey (SF36) were determined preoperatively and at most recent follow-up for all patients. Complications were also noted for all cases.
Results:
The mean Harris Hip Score increased significantly from 47 (32-59; SD=8.3) to 92.3 (65-100; SD=8.2) (p<0.0001). The SF-36 health survey showed an improvement of quality-of-life in all sub-scales. Overall, revision surgery was required in six cases (19 %). Aseptic loosening, leading to implant removal, was noted in five cases. A single-stage revision to address infection was performed in one case. The cumulative survival rate at latest follow-up was 81 %. No other complications were encountered during the study.
Conclusions:
Despite a higher failure rate, compared to total hip arthroplasty in the treatment of primary osteoarthritis, total hip arthroplasty can be considered a feasible option for patients with secondary osteoarthritis of the hip due to slipped capital femoral epiphysis. The current study demonstrates good outcomes in patients treated with a cementless column-preserving prosthesis, which is of particular relevance for this young patient cohort. However, further clinical prospective randomized studies are warranted to provide more definitive evidence.
doi:10.2174/1874325001307010158
PMCID: PMC3664464  PMID: 23730379
Total hip arthroplasty; slipped capital femoral epiphysis.
24.  Uncemented custom femoral components in hip arthroplasty 
Acta Orthopaedica  2010;81(4):427-435.
Background and purpose
We have developed an individually designed, uncemented femoral component for achievement of improved strain distribution and fixation to the bone, to make uncemented stems more applicable in femurs of abnormal size and shape, and to improve the joint mechanics. Here we describe the design of the implant and present the results of a prospective clinical study with at least 7 years of follow-up.
Patients and methods
The prostheses are produced by CAD-CAM technique. The design of the stem is based on CT information, and the neck design is based on the surgeon's planning of the center of rotation, femoral head offset, and leg length correction. The first-generation stem produced before 2001 had a proximal HA coating and a sand-blasted distal part that was down-scaled to avoid contact with compact bone. The second-generation stem had a porous coating beneath the HA layer and the distal part of the stem was polished.
The implant was used in 762 hips (614 patients) from 1995 until 2009. 191 of these hips were followed for 7 years and 83 others were followed for 10 years, and these hips are included in the present study. Mean age at surgery was 48 (20–65) years. Congenital dysplasia of the hip was the reason for osteoarthritis in 46% and 57% of the hips in respective groups. Merle d'Aubigné score was recorded in 152 and 75 hips in the two groups. Prostheses followed for 10 years, and almost all in the 7-year group, were first-generation stems.
Results
The 7- and 10-year cumulative revision rates were 1.1% and 2.4%, respectively, with stem revision for any reason as endpoint. The clinical results were similar at 7 and 10 years, with Merle d'Aubigné scores of 17. Intraoperative trochanteric fissures occurred in 2 of the 191 operations (1.0%); both healed after wiring. In hips followed for 7 years, 2 periprosthetic fractures occurred; exchange of the stem was necessary in both. One additional fracture occurred between 7 and 10 years, and it was treated successfully with osteosynthesis. The rate of dislocation was 1.6% and 2.4%, respectively. There was no radiographic loosening at follow-up.
Interpretation
Use of a custom femoral stem gives a reliable fixation and promising medium-term clinical results in femurs of normal and abnormal shape and dimension. The individual design, which enables optimized joint mechanics, gives a low risk of mechanical complications.
doi:10.3109/17453674.2010.501748
PMCID: PMC2917564  PMID: 20809741
25.  The Exeter femoral stem continues to migrate during its first decade after implantation 
Acta Orthopaedica  2012;83(2):129-134.
Background
Due to its collarless, double-tapered polished design, the Exeter femoral stem is known to migrate distally in the first 5 years after implantation. However, its long-term migration pattern has not been investigated.
Patients and methods
39 consecutive patients (41 total hip arthroplasties) received a cemented Exeter stem and had prospective clinical and RSA follow-up. Patients were evaluated postoperatively at 6, 12, 26, and 52 weeks, and annually thereafter. Short-term results have been reported. In this study, the mean length of follow-up was 9.4 years (SD 3.2 years). No patients were lost to follow-up. 15 patients died during follow-up.
Results
No stems were revised. In 4 stems, fractures of the cement mantle were noted within the first 3 postoperative years. In 3 stems, this resulted in a complete circumferential cement mantle discontinuity. For the 37 well-performing stems, continuous but small migration was measured between 2 and 12 years of follow-up. Continued subsidence of 0.08 mm/year (95% CI: 0.05–0.12, p < 0.001) was seen in combination with continued rotation in retroversion of 0.07°/year (95% CI: 0.02–0.12, p = 0.01). At 10 years of follow-up, mean subsidence was 2.1 (SD 1.2) mm and mean retroversion was 1.8° (SD 2.0). Two-thirds of this occurred during the first 2 postoperative years. In the 3 stems with a complete circumferential cement fracture, a sudden and disproportionately high increase in subsidence was measured in the time period of occurrence.
Interpretation
The Exeter femoral stem continues to migrate during the first decade after implantation. Absolute stability is not required for good long-term survival if this is compatible with the design of the implant.
doi:10.3109/17453674.2012.672093
PMCID: PMC3339525  PMID: 22401676

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