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1.  Three-dimensional mechanical evaluation of joint contact pressure in 12 periacetabular osteotomy patients with 10-year follow-up 
Acta Orthopaedica  2009;80(2):155-161.
Background and purpose Because of the varying structure of dysplastic hips, the optimal realignment of the joint during periacetabular osteotomy (PAO) may differ between patients. Three-dimensional (3D) mechanical and radiological analysis possibly accounts better for patient-specific morphology, and may improve and automate optimal joint realignment.
Patients and methods We evaluated the 10-year outcomes of 12 patients following PAO. We compared 3D mechanical analysis results to both radiological and clinical measurements. A 3D discrete-element analysis algorithm was used to calculate the pre- and postoperative contact pressure profile within the hip. Radiological angles describing the coverage of the joint were measured using a computerized approach at actual and theoretical orientations of the acetabular cup. Quantitative results were compared using postoperative clinical evaluation scores (Harris score), and patient-completed outcome surveys (q-score) done at 2 and 10 years.
Results The 3D mechanical analysis indicated that peak joint contact pressure was reduced by an average factor of 1.7 subsequent to PAO. Lateral coverage of the femoral head increased in all patients; however, it did not proportionally reduce the maximum contact pressure and, in 1 case, the pressure increased. This patient had the lowest 10-year q-score (70 out of 100) of the cohort. Another hip was converted to hip arthroplasty after 3 years because of increasing osteoarthritis.
Interpretation The 3D analysis showed that a reduction in contact pressure was theoretically possible for all patients in this cohort, but this could not be achieved in every case during surgery. While intraoperative factors may affect the actual surgical outcome, the results show that 3D contact pressure analysis is consistent with traditional PAO planning techniques (more so than 2D analysis) and may be a valuable addition to preoperative planning and intraoperative assessment of joint realignment.
PMCID: PMC2689368  PMID: 19404795
2.  Arthroscopy for degenerative knee—a difficult habit to break? 
Acta Orthopaedica  2014;85(3):215-217.
PMCID: PMC4062784  PMID: 24847793
3.  Prosthetic joint infections – a need for health economy studies 
Acta Orthopaedica  2014;85(3):218-220.
PMCID: PMC4062785  PMID: 24758324
4.  Different patient-reported outcomes in immigrants and patients born in Sweden 
Acta Orthopaedica  2014;85(3):221-228.
Background and purpose
Some patients have persistent symptoms after total hip arthroplsty (THA). We investigated whether the proportions of inferior clinical results after total hip arthroplasty—according to the 5 dimensions in the EQ-5D form, and pain and satisfaction according to a visual analog scale (VAS)—are the same in immigrants to Sweden as observed in those born in Sweden.
Records of total hip arthroplasties performed between 1992 and 2007 were retrieved from the Swedish Hip Arthroplasty Register (SHAR) and cross-matched with data from the National Board of Health and Welfare and also Statistics, Sweden. 18,791 operations (1,451 in immigrants, 7.7%) were eligible for analysis. Logistic and linear regression models including age, sex, diagnosis, type of fixation, comorbidity, surgical approach, marital status, and education level were analyzed. Outcomes were the 5 dimensions in EQ-5D, EQ-VAS, VAS pain, and VAS satisfaction. Preoperative data and data from 1 year postoperatively were studied.
Preoperatively (and after inclusion of covariates in the regression models), all immigrant groups had more negative interference concerning self-care. Immigrants from the Nordic countries outside Sweden and Europe tended to have more problems with their usual activities and patients from Europe and outside Europe more often reported problems with anxiety/depression. Patients born abroad showed an overall tendency to report more pain on the VAS than patients born in Sweden.
After the operation, the immigrant groups reported more problems in all the EQ-5D dimensions. After adjustment for covariates including the preoperative baseline value, most of these differences remained except for pain/discomfort and—concerning immigrants from the Nordic countries—also anxiety/depression. After the operation, pain according to VAS had decreased substantially in all groups. The immigrant groups indicated more pain than those born in Sweden, both before and after adjustment for covariates.
The frequency of patients who reported moderate to severe problems, both before and 1 year after the operation, differed for most of the dimensions in EQ-5D between patients born in Sweden and those born outside Sweden.
PMCID: PMC4062786  PMID: 24803309
5.  Dissatisfied patients after total knee arthroplasty 
Acta Orthopaedica  2014;85(3):229-233.
Background and purpose
In 2003, an enquiry by the Swedish Knee Arthroplasty Register (SKAR) 2–7 years after total knee arthroplasty (TKA) revealed patients who were dissatisfied with the outcome of their surgery but who had not been revised. 6 years later, we examined the dissatisfied patients in one Swedish county and a matched group of very satisfied patients.
Patients and methods
118 TKAs in 114 patients, all of whom had had their surgery between 1996 and 2001, were examined in 2009–2010. 55 patients (with 58 TKAs) had stated in 2003 that they were dissatisfied with their knees and 59 (with 60 TKAs) had stated that they were very satisfied with their knees. The patients were examined clinically and radiographically, and performed functional tests consisting of the 6-minute walk and chair-stand test. All the patients filled out a visual analog scale (VAS, 0–100 mm) regarding knee pain and also the Hospital and Anxiety and Depression scale (HAD).
Mean VAS score for knee pain differed by 30 mm in favor of the very satisfied group (p < 0.001). 23 of the 55 patients in the dissatisfied group and 6 of 59 patients in the very satisfied group suffered from anxiety and/or depression (p = 0.001). Mean range of motion was 11 degrees better in the very satisfied group (p < 0.001). The groups were similar with regard to clinical examination, physical performance testing, and radiography.
The patients who reported poor response after TKA continued to be unhappy after 8–13 years, as demonstrated by VAS pain and HAD, despite the absence of a discernible objective reason for revision.
PMCID: PMC4062787  PMID: 24786904
6.  The annual number of hip fractures in Sweden will double from year 2002 to 2050 
Acta Orthopaedica  2014;85(3):234-237.
Background and purpose
The incidence and annual number of hip fractures have increased worldwide during the past 50 years, and projections have indicated a further increase. During the last decade, however, a down-turn in the incidence of hip fracture has been seen in the western world. We predicted the development of hip fractures in Sweden until the year 2050.
We reviewed surgical records for the period 2002–2012 in the city of Malmö, Sweden, and identified patients aged 50 years or more with a hip fracture. We estimated incidence rates by using official population figures as denominator and applied the rates to population projections each year until 2050. We also made projections based on our previously published nationwide Swedish hip fracture rates for the period 1987–2002. Since the projections are based on estimates, no confidence limits are given.
During the period 2002–2012, there were 7,385 hip fractures in Malmö. Based on these data, we predicted that there would be approximately 30,000 hip fractures in Sweden in the year 2050. Use of nationwide rates for 2002 in the predictive model gave similar results, which correspond to an increase in the number of hip fractures by a factor of 1.9 (1.7 for women and 2.3 for men) compared to 2002.
The annual number of hip fractures will almost double during the first half of the century. Time trends in hip fractures and also changes in population size and age distribution should be continuously monitored, as such changes will influence the number of hip fractures in the future. Our results indicate that we must optimize preventive measures for hip fractures and prepare for major demands in resources.
PMCID: PMC4062788  PMID: 24786906
7.  Projections of total hip replacement in Sweden from 2013 to 2030 
Acta Orthopaedica  2014;85(3):238-243.
Background and purpose
The continuously increasing demand for joint replacement surgery in the past decades imposes higher constraints on the budgets of hospitals and healthcare providers. We undertook an analysis of historical trends in total hip replacement performed in Sweden between 1968 and 2012 in order to provide projections of future demand.
Data and methods
We obtained data on total hip replacements registered every year and on the evolution of the Swedish population between 1968 and 2012. We assumed the existence of a maximum incidence. So we adopted a regression framework that assumes the existence of an upper limit of total hip replacement incidence.
We found that the incidence of total hip replacement will continue to increase until a projected upper incidence level of about 400 total hip replacements per 105 Swedish residents aged 40 years and older will be reached around the year 2107. In 2020, the estimated incidence of total hip replacement will be 341 (95% prediction interval (PI): 302–375) and in 2030 it will be 358 (PI: 317–396). Using official forecasted population growth data, about 18,000 operations would be expected to be performed in 2020 and 20,000 would be expected to be performed in 2030.
Growing incidence, population growth, and increasing life expectancy will probably result in increased demand for hip replacement surgery. Our findings could serve as a basis for decision making.
PMCID: PMC4062789  PMID: 24758323
8.  Age- and health-related quality of life after total hip replacement 
Acta Orthopaedica  2014;85(3):244-249.
While age is a common confounder, its impact on health-related quality of life (HRQoL) after total hip replacement is uncertain. This could be due to improper statistical modeling of age in previous studies, such as treating age as a linear variable or by using age categories. We hypothesized that there is a non-linear association between age and HRQoL.
We selected a nationwide cohort from the Swedish Hip Arthroplasty Register of patients operated with total hip replacements due to primary osteoarthritis between 2008 and 2010. For estimating HRQoL, we used the generic health outcome questionnaire EQ-5D of the EuroQol group that consits or 2 parts: the EQ-5D index and the EQ VAS estimates.
Using linear regression, we modeled the EQ-5D index and the EQ VAS against age 1 year after surgery. Instead of using a straight line for age, we applied a method called restricted cubic splines that allows the line to bend in a controlled manner. Confounding was controlled by adjusting for preoperative HRQoL, sex, previous contralateral hip surgery, pain, and Charnley classification.
Complete data on 27,245 patients were available for analysis. Both the EQ-5D index and EQ VAS showed a non-linear relationship with age. They were fairly unaffected by age until the patients were in their late sixties, after which age had a negative effect.
There is a non-linear relationship between age and HRQoL, with improvement decreasing in the elderly.
PMCID: PMC4062790  PMID: 24786908
9.  Revision rate after short-stem total hip arthroplasty 
Acta Orthopaedica  2014;85(3):250-258.
Background and purpose
The aim of short-stem total hip arthroplasty is to preserve proximal bone stock for future revisions, to improve biomechanical reconstruction, and to make minimally invasive approaches easier. It is therefore being increasingly considered to be a sound alternative to conventional total hip arthroplasty, especially for young and active patients. However, it is still unknown whether survival rates of short-stem hips match current standards. We made a systematic summary of reported overall survival after short-stem total hip arthroplasty.
Materials and methods
We conducted a systematic review of English, French, German, and Dutch literature. 2 assessors independently identified clinical studies on short-stem hip arthroplasty. After recalculating reported revision rates, we determined whether each implant had a projected revision rate of 10% or less at 10 years of follow-up or a revision rate per 100 observed component years of 1 or less. Stems were classified as “collum”, “partial collum”, or “trochanter-sparing”.
Results and Interpretation
We found 49 studies, or 51 cohorts, involving 19 different stems. There was a large increase in recent publications. The majority of studies included had a follow-up of less than 5 years. We found a large number of observational studies on “partial collum” and “trochanter-sparing” stems, demonstrating adequate survival rates at medium-term follow-up. Clinical evidence from “collum stem” studies was limited to a small number of studies with a medium-term follow-up period. These studies did not show a satisfactory overall survival rate.
PMCID: PMC4062791  PMID: 24694271
10.  Changes in blood ion levels after removal of metal-on-metal hip replacements 
Acta Orthopaedica  2014;85(3):259-265.
Background and purpose
In patients with metal-on-metal (MoM) hip prostheses, pain and joint effusions may be associated with elevated blood levels of cobalt and chromium ions. Since little is known about the kinetics of metal ion clearance from the body and the rate of resolution of elevated blood ion levels, we examined the time course of cobalt and chromium ion levels after revision of MoM hip replacements.
Patients and methods
We included 16 patients (13 female) who underwent revision of a painful MoM hip (large diameter, modern bearing) without fracture or infection, and who had a minimum of 4 blood metal ion measurements over an average period of 6.1 (0–12) months after revision.
Average blood ion concentrations at the time of revision were 22 ppb for chromium and 43 ppb for cobalt. The change in ion levels after revision surgery varied extensively between patients. In many cases, over the second and third months after revision surgery ion levels decreased to 50% of the values measured at revision. Decay of chromium levels occurred more slowly than decay of cobalt levels, with a 9% lag in return to normal levels. The rate of decay of both metals followed second-order (exponential) kinetics more closely than first-order (linear) kinetics.
The elimination of cobalt and chromium from the blood of patients who have undergone revision of painful MoM hip arthroplasties follows an exponential decay curve with a half-life of approximately 50 days. Elevated blood levels of cobalt and chromium ions can persist for at least 1 year after revision, especially in patients with high levels of exposure.
PMCID: PMC4062792  PMID: 24758321
11.  Corticosteroid administration within 2 weeks after renal transplantation affects the incidence of femoral head osteonecrosis 
Acta Orthopaedica  2014;85(3):266-270.
Background and purpose
It has been suggested that avascular osteonecrosis (AVN) of the femoral head occurs early after systemic steroid administration. The purpose of this study was to investigate the risks regarding development of AVN at a very early stage after renal transplantation.
The presence or absence of AVN was determined by MRI at 4 weeks, at 6–12 weeks, at 24 weeks, and at 12 months after renal transplantation in 286 patients (183 males) with a mean age of 39 (16–65) years. The relationship between AVN and age, sex, absence or presence of acute rejection (AR), type of transplanted kidney (living or cadaveric), type of immune suppressor, and total dose of orally administered steroids given in the 2-week period after transplantation was investigated.
There were no statistically significant correlations between the development of AVN and age, sex, absence or presence of AR, type of transplanted kidney, or type of immune suppressor. A significant dose-response relationship was found between development of AVN and the total dose of steroid administered in the first 2 weeks after surgery.
We found a relationship between AVN development and steroid dose in the early postoperative period, and we also showed a dose-response relationship.
PMCID: PMC4062793  PMID: 24786907
12.  In vivo and ex vivo measurement of polyethylene wear in total hip arthroplasty 
Acta Orthopaedica  2014;85(3):271-275.
Determination of the amount of wear in a polyethylene liner following total hip arthroplasty (THA) is important for both the clinical care of individual patients and the development of new types of liners.
Patients and methods
We measured in vivo wear of the polyethylene liner using computed tomography (CT) (obtained in the course of regular clinical care) and compared it to coordinate-measuring machine (CMM) readings. Also, changes in liner thickness of the same retrieved polyethylene liner were measured using a micrometer, and were compared to CT and CMM measurements. The distance between the centers of the acetabular cup and femoral head component was measured in 3D CT, using a semi-automatic analysis method. CMM readings were performed on each acetabular liner and data were analyzed using 3D computer-aided design software. Micrometer readings compared the thickest and thinnest regions of the liner. We analyzed 10 THA CTs and retrievals that met minimal requirements for CT slice thickness and explanted cup condition.
For the 10 cups, the mean difference between the CT readings and the CMM readings was -0.09 (–0.38 to 0.20) mm. This difference was not statistically significant (p = 0.6). Between CT and micrometer, the mean difference was 0.11 (–0.33 to 0.55) mm. This difference was not statistically significant (p = 0.6).
Our results show that CT imaging is ready to be used as a tool in clinical wear measurement of polyethylene liners used in THA.
PMCID: PMC4062794  PMID: 24758322
13.  Excellent results with the cemented Lubinus SP II 130-mm femoral stem at 10 years of follow-up 
Acta Orthopaedica  2014;85(3):276-279.
Background and purpose
The Lubinus SP II stem is well documented in both orthopedic registries and clinical studies. Worldwide, the most commonly used stem lengths are 150 mm and 170 mm. In 1995, the 130-mm stem was introduced, but no outcome data have been published. We assessed the long-term survival of the Lubinus SP II 130-mm stem in primary total hip arthroplasty.
Patients and methods
In a retrospective cohort study, we evaluated 829 patients with a Lubinus SP II primary total hip arthroplasty (932 hips). The hips were implanted between 1996 and 2001. The primary endpoint was revision for any reason. The mean follow-up period was 10 (5–15) years.
Survival analysis showed an all-cause 10-year survival rate of the stem of 98.7% (95% CI: 99.7–97.7), and all-cause 10-year survival of the total hip arthroplasty was 98.3% (95% CI: 99.3–97.3).
Excellent long-term results can be achieved with the cemented Lubinus SP II with the relatively short 130-mm stem. This stem has potential advantages over its 150-mm and 170-mm siblings such as bone preservation distal to the stem, better proximal filling around the prosthesis, and easier removal.
PMCID: PMC4062795  PMID: 24694276
14.  Histology of 8 atypical femoral fractures 
Acta Orthopaedica  2014;85(3):280-286.
Background and purpose
The pathophysiology behind bisphosphonate-associated atypical femoral fractures remains unclear. Histological findings at the fracture site itself may provide clues.
Patients and methods
Between 2008 and 2013, we collected bone biopsies including the fracture line from 4 complete and 4 incomplete atypical femoral fractures. 7 female patients reported continuous bisphosphonate use for 10 years on average. 1 patient was a man who was not using bisphosphonates. Dual-energy X-ray absorptiometry of the hip and spine showed no osteoporosis in 6 cases. The bone biopsies were evaluated by micro-computed tomography, infrared spectroscopy, and qualitative histology.
Incomplete fractures involved the whole cortical thickness and showed a continuous gap with a mean width of 180 µm. The gap contained amorphous material and was devoid of living cells. In contrast, the adjacent bone contained living cells, including active osteoclasts. The fracture surfaces sometimes consisted of woven bone, which may have formed in localized defects caused by surface fragmentation or resorption.
Atypical femoral fractures show signs of attempted healing at the fracture site. The narrow width of the fracture gap and its necrotic contents are compatible with the idea that micromotion prevents healing because it leads to strains within the fracture gap that preclude cell survival.
PMCID: PMC4062796  PMID: 24786905
15.  Large increase in arthroscopic meniscus surgery in the middle-aged and older population in Denmark from 2000 to 2011 
Acta Orthopaedica  2014;85(3):287-292.
Arthroscopic meniscal surgery is the most common orthopedic procedure, and the incidence has increased in Denmark over the last 10 years. Concomitantly, several randomized controlled trials have shown no benefit of arthroscopic procedures including arthroscopic partial meniscectomy in middle-aged and older individuals suffering from knee pain with or without knee osteoarthritis. We examined the annual incidence of meniscal procedures together with age, sex, and diagnosis for patients who underwent meniscal procedures in the period 2000–2011 in Denmark.
Data on age, sex, diagnosis, and surgical procedures were extracted from the Danish National Patient Register for the years 2000–2011, for all records containing meniscal surgery as a primary or secondary procedure.
The overall annual incidence of meniscal procedures per 100,000 persons in Denmark doubled from 164 in 2000 to 312 in 2011 (i.e. 8,750 procedures to 17,368 procedures). A 2-fold increase was found for patients aged between 35 and 55, and a 3-fold increase was found for those older than 55. Middle-aged and older patients accounted for 75% of all 151,228 meniscal procedures carried out between 2000 and 2011.
The incidence of meniscal procedures performed in Denmark doubled from 2000 to 2011, with the largest increase in middle-aged and older patients. This increase contrasts with the mounting evidence showing no added benefit of arthroscopic partial meniscectomy over non-surgical treatments. Our observations illustrate the long delay in the dissemination, acceptance, and implementation of research evidence into the practice of arthroscopic surgery.
PMCID: PMC4062797  PMID: 24800623
16.  How precise is the PRECICE compared to the ISKD in intramedullary limb lengthening? 
Acta Orthopaedica  2014;85(3):293-298.
Background and purpose
The PRECICE intramedullary limb lengthening system uses a new technique with a magnetic rod and a motorized external remote controller (ERC) with rotational magnetic field. We evaluated the reliability and safety of the PRECICE system.
We compared our preliminary results with PRECICE in 24 patients (26 nails) with the known difficulties in the use of mechanical lengthening devices such as the ISKD. We used the Paley classification for evaluation of problems, obstacles, and complications.
2 nails were primarily without function, and 24/26 nails lengthened over the desired distance. Lengthening desired was 38 mm and lengthening obtained was 37 mm. There were 2 nail breakages, 1 in the welding seam and 1 because of a fall that occurred during consolidation. ERC usage was problematic mostly in patients with femoral lengthening. Adjustment of the ERC was necessary in 10 of 24 cases. 15 cases had implant-associated problems, obstacles were seen in 5 cases, and complications were seen in each of 4 cases.
The reliability of the PRECICE system is comparable to that of other intramedullary lengthening devices such as the ISKD. The motorized external remote controller and its application by the patients is a weak point of the system and needs strict supervision.
PMCID: PMC4062798  PMID: 24758320
17.  Distal tibia fractures: locked or non-locked plating? 
Acta Orthopaedica  2014;85(3):299-304.
Background and purpose
Although plating is considered to be the treatment of choice in distal tibia fractures, controversies abound regarding the type of plating for optimal fixation. We conducted a systematic review to evaluate and compare the outcomes of locked plating and non-locked plating in treatment of distal tibia fractures.
Patients and methods
A systematic review was conducted using PubMed to identify articles on the outcomes of plating in distal tibia fractures that were published up to June 2012. We included English language articles involving a minimum of 10 adult cases with acute fractures treated using single-plate, minimally invasive techniques. Study-level binomial regression on the pooled data was conducted to determine the effect of locking status on different outcomes, adjusted for age, sex, and other independent variables.
27 studies met the inclusion criteria and were included in the final analysis of 764 cases (499 locking, 265 non-locking). Based on descriptive analysis only, delayed union was reported in 6% of cases with locked plating and in 4% of cases with non-locked plating. Non-union was reported in 2% of cases with locked plating and 3% of cases with non-locked plating. Comparing locked and non-locked plating, the odds ratio (OR) for reoperation was 0.13 (95% CI: 0.03–0.57) and for malalignment it was 0.10 (95% CI: 0.02–0.42). Both values were statistically significant.
This study showed that locked plating reduces the odds of reoperation and malalignment after treatment for acute distal tibia fracture. Future studies should accurately assess causality and the clinical and economic impact of these findings.
PMCID: PMC4062799  PMID: 24758325
18.  18F-FDG microPET imaging differentiates between septic and aseptic wound healing after orthopedic implant placement 
Acta Orthopaedica  2014;85(3):305-313.
Background and purpose
18F-FDG PET is a widely used tool for molecular imaging of oncological, cardiovascular, and neurological disorders. We evaluated 18F-FDG microPET as an implant osteomyelitis imaging tool using a Staphylococcus aureus-induced peroperative implant infection in rabbits.
Intramedullary titanium nails were implanted in contaminated and uncontaminated (control) proximal right tibiae of rabbits. Tibiae were quantitatively assessed with microPET for 18F-FDG uptake before and sequentially at 1, 3, and 6 weeks after surgery. Tracer uptake was assessed in soft tissue and bone in both treatment groups with an additional comparison between the operated and unoperated limb. MicroPET analysis was combined with radiographic assessment and complementary histology of the tibiae.
At the first postoperative week, the 18F-FDG uptake in the contaminated implant group was significantly higher than the preoperative measurement, without a significant difference between the contaminated and uncontaminated tibiae. From the third postoperative week onward, 18F-FDG uptake allowed discrimination between osteomyelitis and postoperative aseptic bone healing, as well as quantification of the infection at distinct locations around the implant.
18F-FDG-based microPET imaging allows differentiation between deep infection and undisturbed wound healing after implantation of a titanium intramedullary nail in this rabbit model. Furthermore, our results indicate that 18F-FDG PET may provide a tool in human clinical diagnostics and for the evaluation of antimicrobial strategies in animal models of orthopedic implant infection.
PMCID: PMC4062800  PMID: 24673540
19.  Guideline for diagnosis and treatment of subacromial pain syndrome 
Acta Orthopaedica  2014;85(3):314-322.
Treatment of “subacromial impingement syndrome” of the shoulder has changed drastically in the past decade. The anatomical explanation as “impingement” of the rotator cuff is not sufficient to cover the pathology. “Subacromial pain syndrome”, SAPS, describes the condition better. A working group formed from a number of Dutch specialist societies, joined by the Dutch Orthopedic Association, has produced a guideline based on the available scientific evidence. This resulted in a new outlook for the treatment of subacromial pain syndrome. The important conclusions and advice from this work are as follows:
(1) The diagnosis SAPS can only be made using a combination of clinical tests. (2) SAPS should preferably be treated non-operatively. (3) Acute pain should be treated with analgetics if necessary. (4) Subacromial injection with corticosteroids is indicated for persistent or recurrent symptoms. (5) Diagnostic imaging is useful after 6 weeks of symptoms. Ultrasound examination is the recommended imaging, to exclude a rotator cuff rupture. (6) Occupational interventions are useful when complaints persist for longer than 6 weeks. (7) Exercise therapy should be specific and should be of low intensity and high frequency, combining eccentric training, attention to relaxation and posture, and treatment of myofascial trigger points (including stretching of the muscles) may be considered. (8) Strict immobilization and mobilization techniques are not recommended. (9) Tendinosis calcarea can be treated by shockwave (ESWT) or needling under ultrasound guidance (barbotage). (10) Rehabilitation in a specialized unit can be considered in chronic, treatment resistant SAPS, with pain perpetuating behavior. (11) There is no convincing evidence that surgical treatment for SAPS is more effective than conservature management. (12) There is no indication for the surgical treatment of asymptomatic rotator cuff tears.
PMCID: PMC4062801  PMID: 24847788
20.  Prognostic factors for local recurrence and mortality in adult soft tissue sarcoma of the extremities and trunk wall 
Acta Orthopaedica  2014;85(3):323-332.
Background and purpose
Previous studies of soft tissue sarcoma (STS) have identified a number of possible prognostic factors; however, the majority of these include highly selected populations, with unclear validation of data and insufficient statistical methods. We identified prognostic factors in a validated, population-based 30-year series of STS treated at a single institution, using an advanced statistical approach.
Patients and methods
Between 1979 and 2008, 922 adult patients from western Denmark were treated at the Aarhus Sarcoma Center for non-metastatic STS in the extremities or trunk. The endpoints were local recurrence (LR) and disease-specific mortality (DSM). Prognostic factors were analyzed using a proportional hazard model, including continuous variables as cubic splines. Directed acyclic graphs were used to depict the causal structure.
The 5-year LR was 16% and the 5-year DSM was 24%. Important prognostic factors for both LR and DSM were age, duration of symptoms, tumor size, grade, margin, and radiotherapy, while anatomical location (upper, lower extremity, trunk) was prognostic for DSM.
In this population-based series of adult, non-metastatic STS, we included directed acyclic graphs, cubic splines, and a competing risk model in order to minimize bias, and demonstrated that these statistical methods are feasible. Using these statistical methods on a large, validated dataset, we excluded depth as a prognostic factor and established that age, duration of symptoms, size, grade, margin, and radiotherapy were important prognostic factors for both local recurrence and disease-specific mortality.
PMCID: PMC4062802  PMID: 24694277
21.  Bone transport of the tibia with a motorized intramedullary lengthening nail — a case report 
Acta Orthopaedica  2014;85(3):333.
PMCID: PMC4062803  PMID: 24694274
22.  Cemented or uncemented hemiarthroplasty for the treatment of femoral neck fractures? 
Acta Orthopaedica  2014;85(3):334.
PMCID: PMC4062804  PMID: 24847794
23.  Countrywise results of total hip replacement 
Acta Orthopaedica  2014;85(2):107-116.
Background and purpose
An earlier Nordic Arthroplasty Register Association (NARA) report on 280,201 total hip replacements (THRs) based on data from 1995–2006, from Sweden, Norway, and Denmark, was published in 2009. The present study assessed THR survival according to country, based on the NARA database with the Finnish data included.
Material and methods
438,733 THRs performed during the period 1995–2011 in Sweden, Denmark, Norway, and Finland were included. Kaplan-Meier survival analysis was used to calculate survival probabilities with 95% confidence interval (CI). Cox multiple regression, with adjustment for age, sex, and diagnosis, was used to analyze implant survival with revision for any reason as endpoint.
The 15-year survival, with any revision as an endpoint, for all THRs was 86% (CI: 85.7–86.9) in Denmark, 88% (CI: 87.6–88.3) in Sweden, 87% (CI: 86.4–87.4) in Norway, and 84% (CI: 82.9–84.1) in Finland. Revision risk for all THRs was less in Sweden than in the 3 other countries during the first 5 years. However, revision risk for uncemented THR was less in Denmark than in Sweden during the sixth (HR = 0.53, CI: 0.34–0.82), seventh (HR = 0.60, CI: 0.37–0.97), and ninth (HR = 0.59, CI: 0.36–0.98) year of follow-up.
The differences in THR survival rates were considerable, with inferior results in Finland. Brand-level comparison of THRs in Nordic countries will be required.
PMCID: PMC3967250  PMID: 24650019
24.  Patient-reported outcome and risk of revision after shoulder replacement for osteoarthritis 
Acta Orthopaedica  2014;85(2):117-122.
We used patient-reported outcome and risk of revision to compare hemiarthroplasty (HA) with total shoulder arthroplasty (TSA) and stemmed hemiarthroplasty (SHA) with resurfacing hemiarthroplasty (RHA) in patients with glenohumeral osteoarthritis.
Patients and methods
We included all patients reported to the Danish Shoulder Arthroplasty Registry (DSR) between January 2006 and December 2010. 1,209 arthroplasties in 1,109 patients were eligible. Western Ontario Osteoarthritis of the Shoulder index (WOOS) was used to evaluate patient-reported outcome 1 year postoperatively. For simplicity of presentation, the raw scores were converted to a percentage of the maximum score. Revision rates were calculated by checking reported revisions to the DSR until December 2011. WOOS and risk of revision were adjusted for age, sex, previous surgery, and type of osteoarthritis.
There were 113 TSAs and 1096 HAs (837 RHAs and 259 SHAs). Patients treated with TSA generally had a better WOOS, exceeding the predefined minimal clinically important difference, at 1 year (mean difference 10, p < 0.001). RHA had a better WOOS than SHA (mean difference 5, p = 0.02), but the difference did not exceed the minimal clinically important difference. There were no statistically significant differences in revision rate or in adjusted risk of revision between any of the groups.
Our results are in accordance with the results from other national shoulder registries and the results published in systematic reviews favoring TSA in the treatment of glenohumeral osteoarthritis. Nonetheless, this registry study had certain limitations and the results should be interpreted carefully.
PMCID: PMC3967251  PMID: 24650020
25.  The effect of femoral offset modification on gait after total hip arthroplasty 
Acta Orthopaedica  2014;85(2):123-127.
Background and purpose
A decrease of 15% in femoral offset (FO) has been reported to generate a weakness of the abductor muscle, but this has not been directly linked to an alteration of gait. Our hypothesis was that this 15% decrease in FO may also generate a clinically detectable alteration in the gait.
Patients and methods
We performed a prospective comparative study on 28 patients who underwent total hip arthroplasty (THA) for unilateral primary osteoarthritis. The 3D hip anatomy was analyzed preoperatively and postoperatively. 3 groups were defined according to the alteration in FO following surgery: a minimum decrease of 15% (9 patients), restored (14), and a minimum increase of 15% (5). A gait analysis was performed at 1-year follow-up using an ambulatory device. Each limb was compared to the contralateral healthy limb.
In contrast to the “restored” group and the “increased” group, in the “decreased” group there was a statistically significant asymmetry between sides, with reduced range of motion and a lower maximal swing speed on the operated side.
A decrease in FO of 15% or more after THA leads to an alteration in the gait. We recommend 3-D preoperative planning because the FO may be underestimated by up to 20% on radiographs and it may therefore not be restored, with clinical consequences.
PMCID: PMC3967252  PMID: 24564749

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