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1.  High Incidence of Migration with Poor Initial Fixation of the Accolade® Stem 
Background
Numerous cementless femoral stem design variations are in clinical use. Because initial implant instability and micromotion are associated with aseptic loosening of the femoral component, migration analysis provides an early assessment of implant survivorship.
Questions/purposes
We determined the (1) migration pattern of the Accolade® cementless femoral stem; (2) clinical factors predisposing to stem migration; (3) self-reported patient outcomes; and (4) our current rate of aseptic stem loosening.
Methods
We retrospectively analyzed 81 femoral stems for aseptic migration using Ein-Bild-Roentgen-Analyse-femoral component analysis. Postoperatively, patients completed the WOMAC and SF-12 questionnaires. We assessed radiographic factors potentially associated with subsidence: indices of bone shape and quality, canal fill of the implant, and radiographic signs of loosening. Minimum followup was 24 months (mean, 29 months; range, 24–48 months).
Results
The average subsidence at 24 months was 1.3 mm (range, 0–1.5 mm). In the first 2 years, 36% of stems subsided more than 1.5 mm. Large stem size was associated with subsidence. Radiolucent lines (> 1.5 mm in three zones) were present in 10% of stems and associated with lower questionnaire scores. The 5-year survivorship for aseptic loosening of the 367 stems was 97% with revision as end point and 95% for radiographic failure.
Conclusions
The high incidence of migration and stems with radiographic failure raises concerns about patient clinical function and long-term survivorship of this stem design. This migration pattern may be due to poor initial stability with a subsequent lack of osseointegration. Our results differ from radiographic findings and clinical durability of other similar cementless stem designs.
Level of Evidence
Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-011-2160-z
PMCID: PMC3254738  PMID: 22045070
2.  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
3.  5-year clinical and radiostereometric analysis (RSA) follow-up of 39 CUT femoral neck total hip prostheses in young osteoarthritis patients 
Acta Orthopaedica  2012;83(4):334-341.
Background
As the number of young patients receiving total hip arthroplasty increases, bone-saving implantations facilitating possible future revision, such as the CUT femoral neck prosthesis, are gaining importance. There have been few medium-term results reported for this prosthesis, however, and its migration pattern has not been analyzed.
Patients and methods
39 consecutive CUT femoral neck prostheses were implanted in 32 patients, mean age 37 (17–58) years, with symptomatic osteoarthritis and either less than 55 years of age or with an anatomic anomaly preventing implantation of a diaphyseal stem (n = 1). Patients were followed prospectively using routine clinical examination and radiostereometric analysis (RSA) at 6, 12, 26, and 52 weeks postoperatively and annually thereafter. This study evaluated the 5-year follow-up results.
Results
The mean Harris hip score increased from 26 (3–51) points preoperatively to 84 (66–98), 86 (55–98), and 87 (47–98) points at 3, 12, and 60 months. 3 stems were revised: 1 after luxation following excessive subsidence due to an undersized component and 2 due to persistent strong thigh pain. 5-year survival was 95% (95% CI: 87–100). Initial migration varied widely in magnitude; median total tip migration was 0.42 mm (0.09–9.4) at 6 weeks, 0.92 mm (0.18–5.9) at 1 year, and 1.10 mm (0.13–6.4) at 5 years. Even after high initial migration, stabilization was achieved in 31 of the 35 RSA-evaluable implants. 3 prostheses showed progressive continuous migration throughout the entire follow-up period, and were considered to be loose, suggesting reduced long-term survival.
Interpretation
Currently, we cannot recommend the CUT femoral neck prosthesis as a routine treatment option in (young) patients requiring THA. The CUT prosthesis may not reach the 90% survival benchmark at 10 years, and the prosthesis is difficult to implant. If initial stabilization is achieved, however, aseptic loosening is unlikely. A good clinical outcome was seen in the surviving prostheses. We will continue to follow this patient group.
doi:10.3109/17453674.2012.702392
PMCID: PMC3427622  PMID: 22880707
4.  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
5.  Subsidence of a cementless femoral component influenced by body weight and body mass index 
International Orthopaedics  2011;36(5):941-947.
Purpose
This trial was designed to evaluate the impact of physical characteristics such as body mass index, body weight and height on distal stem migration of a cementless femoral component, as the influence of obesity on the outcome of THA is still debated in literature and conflicting results have been found.
Methods
In this retrospective cohort study, migration patterns for 102 implants were analysed using the Einzel-Bild-Roentgen-Analyse (EBRA-FCA, femoral component analysis). In all cases the Vision 2000 stem was implanted and combined with the Duraloc acetabular component (DePuy, Warsaw, Indiana).
Results
The mean follow-up was 93 months. EBRA-FCA evaluations revealed a mean subsidence of 1.38 mm after two years, 2.06 mm after five and 2.24 mm after seven years. Five stems loosened aseptically. Correlation between increased migration over the whole period and aseptic loosening was highly significant (p < 0.001). Surgical technique had a significant influence on migration and stem stability (p = 0.002) but physical patient characteristics such as body weight over 75 kg and height over 165 cm also significantly influenced stem subsidence towards progressive migration (p = 0.001, p < 0.001). However, a high BMI did not trigger progressive stem migration (p = 0.87). Being of the male gender raised the odds for increased migration (p = 0.03).
Conclusion
Physical characteristics such as body weight and height showed significant influence on migration patterns of this cementless femoral component. The operating surgeon should be aware that body weight above 75 kg and height over 165 cm may trigger increased stem migration and the surgeon should aim to fit these prostheses as tightly as possible. However this study demonstrates that a high BMI does not trigger progressive stem migration. Further investigations are needed to confirm our findings.
doi:10.1007/s00264-011-1360-1
PMCID: PMC3337099  PMID: 22052477
Medicine & Public Health; Orthopedics
6.  The beneficial effect of hydroxyapatite lasts 
Acta Orthopaedica  2012;83(2):135-141.
Background and purpose
In contrast to early migration, the long-term migration of hydroxyapatite- (HA-) coated tibial components in TKA has been scantily reported. This randomized controlled trial investigated the long-term migration measured by radiostereometric analysis (RSA) of HA-coated, uncoated, and cemented tibial components in TKA.
Patients and methods
68 knees were randomized to HA-coated (n = 24), uncoated (n = 20), and cemented (n = 24) components. All knees were prospectively followed for 11–16 years, or until death or revision. RSA was used to evaluate migration at yearly intervals. Clinical and radiographic evaluation was according to the Knee Society system. A generalized linear mixed model (GLMM, adjusted for age, sex, diagnosis, revisions, and BMI) was used to take into account the repeated-measurement design.
Results
The present study involved 742 RSA analyses. The mean migration at 10 years was 1.66 mm for HA, 2.25 mm for uncoated and 0.79 mm for the cemented group (p < 0.001). The reduction of migration by HA as compared to uncoated components was most pronounced for subsidence and external rotation. 3 tibial components were revised for aseptic loosening (2 uncoated and 1 cemented), 3 for septic loosening (2 uncoated and 1 cemented), and 1 for instability (HA-coated). 2 of these cases were revised for secondary loosening after a period of stability: 1 case of osteolysis and 1 case of late infection. There were no statistically significant differences between the fixation groups regarding clinical or radiographic scores.
Interpretation
HA reduces migration of uncemented tibial components. This beneficial effect lasts for more than 10 years. Cemented components showed the lowest migration. Longitudinal follow-up of TKA with RSA allows early detection of secondary loosening.
doi:10.3109/17453674.2012.665330
PMCID: PMC3339526  PMID: 22329667
7.  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
8.  A prospective randomized study comparing electrochemically deposited hydroxyapatite and plasma-sprayed hydroxyapatite on titanium stems 
Acta Orthopaedica  2011;82(1):13-19.
Background and purpose
Plasma-sprayed hydroxyapatite (HA) is a successful coating for fixation of uncemented femoral stems. There may be alternative coatings with advantages in bone remodeling and transport of bone-active substances. We investigated whether an electrochemically deposited hydroxyapatite, Bonemaster (BM), might be a safe alternative in total hip arthroplasty. Our hypothesis was that the new coating would not be inferior to the conventional one.
Patients and methods
50 patients (55 hips) were included. The stem was tapered and porous-coated proximally. On top of the porous coating was either HA or BM. Patients were evaluated postoperatively and after 3, 6, 12, and 24 months to measure fixation by radiostereometric analysis (RSA), bone mineral density by dual-energy X-ray absorptiometry (DXA), and conventional radiography. Clinical evaluation was performed with Harris hip score and Oxford hip score, both preoperatively and after 2 years.
Results
After 2 years, the stems had subsided 0.25 (HA) and 0.28 (BM) mm and there were no statistically significant differences between the groups in any direction, regarding both migration and rotation. The BM group retained significantly more bone than the HA group in Gruen zone 1 during the first 2 years. The Harris and Oxford hip scores were similar in both groups.
Interpretation
Electrochemically deposited hydroxyapatite on an uncemented stem does not appear to be inferior to plasma-sprayed HA regarding clinical and radiological results, bone remodeling, and micromotion after 2 years follow-up.
doi:10.3109/17453674.2010.548027
PMCID: PMC3229992  PMID: 21189109
9.  Cementless total hip arthroplasty in rheumatoid arthritis: a systematic review of the literature 
Background
Compromised rheumatic bone is a potential risk factor for mechanical complications in cementless total hip arthroplasty (THA) in cases of rheumatoid arthritis (RA). Increased rates of intra-operative fractures, component migration and (early) aseptic loosening are to be expected. Despite this, cementless THA is performed in cases of RA.
Methods
A literature search on cementless THA in RA was performed in EMBASE (1993–2011), Medline (1966–2011) and the Cochrane Library. A systematic review was conducted with a special emphasis on mechanical complications.
Results
Twenty-three case series and five studies of implant registries were included. Acetabular fractures and/or migration of the cup were reported in 9 out of 22 studies of the cup. Proximal femoral fractures and/or subsidence of the stem were reported in 14 out of 20 studies of the stem. Six studies compared failure rates of uncemented and cemented components due to aseptic loosening. The overall failure rate ratio (uncemented/cemented) for the cup was 0.6 (95% CI: 0.14–2.60) and for the stem 0.71 (95% CI: 0.06–8.55), both favoring uncemented fixation. The failure rates in case series without a control group were compared to the NICE criteria (failure rate/1). The overall failure rate for the cup was 0.97 (95% CI: 0.50–1.88) and for the stem 0.79 (95% CI: 0.44–1.41). Failure rates of aseptic loosening of higher than 1 (favoring cemented fixation) were reported in 6 out of 26 studies of the cup and in 2 out of 25 studies of the stem. In all these studies, the inferior implant designs were blamed, and not the type of fixation or the quality of the bone.
Conclusions
Despite substantial rates of mechanical stem complications, no evidence was found to establish that cementless components perform less well than cemented components. The results justify the use of cementless THA in RA patients.
doi:10.1007/s00402-011-1432-0
PMCID: PMC3306565  PMID: 22113434
Rheumatoid arthritis; Total hip arthroplasty; Cementless; Uncemented; Review
10.  Is it Time for Cementless Hip Resurfacing? 
HSS Journal  2012;8(3):245-250.
Background
Metal-on-metal bearing with cemented femoral component and cementless acetabular fixation is the current standard in surface replacement arthroplasty (RSA) of the hip. Because of concerns about the long-term survivorship of cemented stems in conventional hip arthroplasty, it seems logical to achieve cementless fixation on the femoral side with RSA.
Questions/Purposes
The goals of this review were to evaluate clinical and radiological data reported from previously published cementless RSA series. In addition, we intend to review author’s preliminary experience with Conserve Plus cementless devices specifically assessing the clinical outcomes, the complications rate, the survivorship, and the metallic ions levels measured in follow-up.
Methods
A references search was done with PubMed using the key words “cementless hip resurfacing”, “cementless hip resurfacing prosthesis”, and “femoral cementless hip resurfacing”. Additionally, the clinical outcomes, the complications rate, the survivorship, and the metallic ions levels were measured in 94 cementless Conserve Plus© devices in 90 patients (68 males and 22 females) with a mean age of 41.1 years (18–59). Mean follow-up was 13.1 months (8–16).
Results
No revision was performed during the observed follow-up. Neither radiological signs of loosening nor neck narrowing >10% were evident. Chromium and cobalt levels in whole blood samples rose respectively from 0.53 μg/l (0.1–1.7) to 1.7 μg/l (0.6–2.9) and from 0.54 μg/l (0.1–1.4) to 1.98 μg/l (0.1–2.8).
Conclusions
Cementless “fit and fill” femoral-side fixation, which seems to be potentially evolved and design-related, should be considered for future hip-resurfacing device generations.
doi:10.1007/s11420-012-9295-7
PMCID: PMC3470669  PMID: 24082868
hip resurfacing; cementless device; cement; bone necrosis
11.  Extensively coated revision stems in proximally deficient femur: Early results in 15 patients 
Indian Journal of Orthopaedics  2008;42(3):287-293.
Background:
Hip replacement following failed internal fixation (dynamic hip screw for intertrochanteric fractures) or previous hip arthroplasty presents a major surgical challenge. Proximal fitting revision stems do not achieve adequate fixation. Distal fixation with long-stemmed extensively coated cementless implants (like the Solution™ system) affords a suitable solution. We present our early results of 15 patients treated with extensively coated cementless revision stems.
Materials and Methods:
Fifteen patients with severely compromised proximal femora following either failed hip arthroplasty or failed internal fixation (dynamic hip screw fixation for intertrochanteric fractures) were operated by the senior author over a two-year period. Eight patients had aseptic loosening of their femoral stems following cemented hip replacements, with severe thinning of their proximal cortices and impending stress fractures. Seven had secondary hip arthritis following failure of long implants for comminuted intertrochanteric or subtrochanteric femoral fractures. All patients were treated by removal of implant (cemented stems/DHS implants) and insertion of long-stemmed extensively coated cementless revision (‘Solution™ DePuy, Warsaw (IN), US’) stems along with press-fit acetabular component (Duraloc Cup, DePuy, Warsaw (IN), US). All eight hip revisions needed extended trochanteric osteotomies.
Results:
All patients were primarily kept in bed on physiotherapy for six weeks and then gradually progressed to weight-bearing walking over the next six to eight weeks. The Harris Hip Scores and patient satisfaction were used for final evaluation. We achieved good results in the short term studied. In our first three patients (all following failed cemented total hip replacements), we resorted to cerclage wiring to hold osteotomised segments (done to facilitate stem removal). The subsequent 12 proceeded without the need for cerclage wiring. One patient had a intraoperative severe comminuted fracture extending into the supracondylar region while hammering in the stem. Post cerclage wiring, she was put on a long knee brace and her mobilization was delayed to 12 weeks.
Conclusions:
The extensively coated cementless (‘Solution™’) femoral stem provides a reasonable ‘solution’ to the deficient femur in hip revision. The proximal femoral deficiences can be relatively easily bypassed and distal fixation can be achieved with this stem. Extreme care needs to be taken to avoid fractures and penetration of the femoral shaft, which can, however, be managed by cerclage wiring. Principles of a successful outcome include preservation of the functional continuity of the abduction apparatus, care to recognize and prevent distal extension of fracture while inserting the stem (preemptive cerclage wiring) and supervised rehabilitation.
doi:10.4103/0019-5413.39554
PMCID: PMC2739478  PMID: 19753154
Cementless fixation; extensively coated; proximally deficient femur
12.  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
13.  A randomized study on migration of the Spectron EF and the Charnley flanged 40 cemented femoral components using radiostereometric analysis at 2 years 
Acta Orthopaedica  2011;82(5):538-544.
Background and purpose
We performed a randomized study to determine the migration patterns of the Spectron EF femoral stem and to compare them with those of the Charnley stem, which is regarded by many as the gold standard for comparison of implants due to its extensive documentation.
Patients and methods
150 patients with a mean age of 70 years were randomized, single-blinded, to receive either a cemented Charnley flanged 40 monoblock, stainless steel, vaquasheen surface femoral stem with a 22.2-mm head (n = 30) or a cemented Spectron EF modular, matte, straight, collared, cobalt-chrome femoral stem with a 28-mm femoral head and a roughened proximal third of the stem (n = 120). The patients were followed with repeated radiostereometric analysis for 2 years to assess migration.
Results
At 2 years, stem retroversion was 2.3° and 0.7° (p < 0.001) and posterior translation was 0.44 mm and 0.17 mm (p = 0.002) for the Charnley group (n = 26) and the Spectron EF group (n = 74), respectively. Subsidence was 0.26 mm for the Charnley and 0.20 mm for the Spectron EF (p = 0.5).
Interpretation
The Spectron EF femoral stem was more stable than the Charnley flanged 40 stem in our study when evaluated at 2 years. In a report from the Norwegian arthroplasty register, the Spectron EF stem had a higher revision rate due to aseptic loosening beyond 5 years than the Charnley. Initial stability is not invariably related to good long-term results. Our results emphasize the importance of prospective long-term follow-up of prosthetic implants in clinical trials and national registries and a stepwise introduction of implants.
doi:10.3109/17453674.2011.618914
PMCID: PMC3242949  PMID: 21895504
14.  Case Report: Cementless Stem Stabilization after Intraoperative Fracture: A Radiostereometric Analysis 
We present the case of a patient with intraoperative femoral fracture during THA, which was repaired using cerclage fixation and insertion of an hydroxyapatite-coated cementless stem. The patient was evaluated postoperatively using radiostereometry during a 2-year course, and despite a large amount of subsidence and rotation, stabilization occurred and was maintained by 6 months. By evaluating the pattern of stem migration after intraoperative fracture, this case shows, even in the presence of instability, a successful clinical outcome can be achieved using an hydroxyapatite-coated cementless stem.
doi:10.1007/s11999-009-1082-5
PMCID: PMC2816748  PMID: 19760467
15.  High 10-Year Survival Rate with an Anatomic Cementless Stem (SPS) 
Background
Proximal cementless fixation using anatomic stems reportedly increases femoral fit and avoids stress-shielding. However, thigh pain was reported with the early stem designs. Therefore, a new anatomic cementless stem design was based on an average three-dimensional metaphyseal femoral shape. However, it is unclear whether this stem reduces the incidence of thigh pain.
Questions/purposes
We asked whether this stem design was associated with a low incidence of thigh pain and provided durable fixation and high function.
Methods
One hundred seventy-one patients (176 THAs) who had the anatomic proximal hydroxyapatite-coated stem implanted were reviewed. Eleven (6%) patients were lost to followup and 34 (20%) died without revision surgery. We used the Harris hip score (HHS) to assess pain and function. We evaluated femoral stem fixation and stability with the score of Engh et al. and also calculated a 10-year survival analysis. We assessed 126 patients (131 hips) at a mean followup of 10 years (range, 8–11 years)
Results
At last followup, two patients described slight thigh pain that did not limit their physical activities. All stems appeared radiographically stable and one stem was graded nonintegrated but stable. Five patients had revision surgery: one on the femoral side (for posttraumatic fracture) and four on the acetabular side. Considering stem revision for aseptic loosening as the end point, survivorship was 100% (range, 95.4%–99.9%) at 10 years.
Conclusion
This anatomic cementless design using only metaphyseal fixation with a wide mediolateral flare, a sagittal curvature, and torsion, allowed durable proximal stem stability and fixation.
Level of Evidence
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-012-2300-0
PMCID: PMC3369068  PMID: 22402808
16.  Excellent results with cementless total hip arthroplasty and alumina-on-alumina pairing: minimum ten-year follow-up 
International Orthopaedics  2010;35(2):195-200.
Ceramic-on-ceramic coupling is thought to be a durable alternative to metal- or alumina-on-polyethylene pairing. No evidence exists suggesting superior clinical and radiological results for hydroxyapatite-coated stems versus uncoated stems. The aim of this study is to report the performance of an alumina-on-alumina bearing cementless total hip arthroplasty and to compare stems with a tapered design with and without hydroxyapatite coating. We prospectively analysed the results of cementless tapered femoral stems (40 hydroxyapatite-coated versus 22 uncoated stems), a metal-backed fibre mesh hydroxyapatite-coated socket and alumina-on-alumina pairing. Of 75 hips studied, 62 were available for follow-up (mean of 10.5 years after surgery). The average Harris hip score was 90. Only one hydroxyapatite-coated stem was revised for aseptic loosening. One instance of non-progressive osteolysis was detected around a screw of a cup. All other components showed radiographic signs of stable ingrowth. Hydroxyapatite coating of the stem had no significant impact on the clinical or radiological results. Total hip arthroplasty with the presented implant and pairing provides a durable standard for all patients requiring hip joint replacement against which all newer generations of cementless implants should be judged.
doi:10.1007/s00264-010-1150-1
PMCID: PMC3032123  PMID: 21079952
17.  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
18.  Influence of cementless femoral stems inserted in varus on functional outcome in primary total hip arthroplasty 
Canadian Journal of Surgery  2006;49(6):407-411.
Introduction
Historically, cemented total hip arthroplasty (THA) femoral stems inserted in varus have yielded poor clinical results. Few studies to date have addressed the question of the effects of varus alignment on cementless stems. We conducted a retrospective review of 125 uncemented THA femoral stems implanted by a single surgeon from 1994 to 1999.
Methods
We conducted a retrospective radiographic review of 125 cementless primary THA femoral stems implanted by a single surgeon who used the Watson-Jones approach; we identified 16 stems implanted in varus, defined as ≥ 5° and thus analyzed the effect of varus alignment on functional outcome. We matched varus stems to a cohort of 16 nonvarus cementless stems and measured radiographic signs of loosening and subsidence, defined as > 2 mm.
Results
At 4 years postsurgery, there was no significant difference in range of motion or in Harris Hip Score (p > 0.5), and no cases showed evidence of radiographic loosening or subsidence (p = 0.226).
Conclusions
Study results suggest there is no consequence of varus femoral alignment in the cementless stems. Although it is not recommended to implant stems in varus, there were no apparent radiographic or clinical consequences observed at up to 4 years postoperative in this small case series.
PMCID: PMC3207554  PMID: 17234069
19.  Proximal cement fixation in total hip arthroplasty—first results with a new stem design 
International Orthopaedics  2007;32(3):295-306.
Stem loosening and stress-shielding are problems encountered in cemented hip arthroplasty. Could proximal stem fixation by partial cementing solve the problem? More physiological transmission of forces with only proximal cement fixation seems to be possible with this recent development (Z-stem, Option 3000, Mathys Orthopaedics, Bettlach, Switzerland). In a prospective clinical trial, this new implant was used for total hip arthroplasty in human patients. One hundred and thirty-three (133) total hip replacements in 123 patients were performed between April 1996 and January 2003. All of them were followed up regularly; 53 were analysed with the EBRA-FCA method (Einzel Bild Röntgen Analyse—femoral component analysis), whereas the rest were analysed using conventional follow-up X-rays. Eighty-six (86) patients with 95 hips could be examined in August 2004 to obtain mid-term results. At this stage, the mean follow-up time was 61 months (5.08 years), with a maximum of 100 months (8.33 years). Up to October 2004, nine cases needed a revision. The clinical data collected reported an average Harris Hip Score of 89.3 (good). The EBRA-FCA analysis reported a mean subsidence of less than 1.5 mm after the first two years, under the EBRA threshold of predicted loosening. At the latest follow-up (at an average of 61 months), there was an average stable subsidence of 2.4 mm in general. Eight (8) patients presented with subsidence of more than 5 mm. The results of the new implant seem to be encouraging. Finally, comparing our results to other fixation concepts will require longer follow-up periods.
doi:10.1007/s00264-006-0316-3
PMCID: PMC2323424  PMID: 17431622
20.  Cementless hemiarthroplasty for femoral neck fractures in elderly patients 
Indian Journal of Orthopaedics  2008;42(1):56-60.
Objectives:
The use of cement is associated with increased morbidity and mortality rate in elderly patients, hence cementless hemiarthroplasty is suggested. We evaluated the results of cementless hemiarthroplasty for femoral neck fractures in elderly patients with high-risk clinical problems.
Materials and Methods:
Forty-eight patients (29 females, 19 males) with a mean age of 88 years (range: 78 to 102 years). having femoral neck fractures were treated with the use of cementless hemiarthroplasty. Porous-coated femoral stems were used in 30 patients (62%) and modular type femoral revision stems in 18 patients (38%). Bipolar femoral heads were used in all patients. Radiological follow-up after operation was done at the one, three, six months and annually.
Results:
The mean follow-up period was 4.2 years (range: 18 months to eight years). None of the patients died during hospitalization. Medical complications occurred in six patients (12%) within the follow-up period and four patients (8%) died within this period. Only two hips were converted to total hip arthroplasty due to acetabular erosion. Femoral revision was planned for one patient with a subsidence of > 3 mm. None of the patients had acetabular protrusion or heterotopic ossification. The mean Harris-hip score was 84 (range: 52 to 92). Dislocation occured in one patient (2%).
Conclusion:
Cementless hemiarthroplasty is a suitable method of treatment for femoral neck fractures in elderly patients with high-risk clinical problems especially of a cardiopulmonary nature. This method decreases the risk of hypotension and fat embolism associated with cemented hemiarthroplasty.
doi:10.4103/0019-5413.38582
PMCID: PMC2759587  PMID: 19823656
Cementless femoral prosthesis; cementless hemiarthroplasty; femoral neck fracture; hemiarthroplasty in elderly
21.  THA Using an Anatomic Stem in Patients With Femoral Head Osteonecrosis 
Treating young patients with femoral head osteonecrosis (ON) remains challenging. Anatomic stems were introduced in the 1980s and 1990s to improve the proximal canal fit in an attempt to enhance long-term implant survival, an important aspect of treating young patients. We began using one design in 1993 and asked three questions to confirm whether the design criteria improved outcomes in patients with ON: (1) What is the long term survivorship of these implants?; (2) What is the amount and rate of wear?; and (3) What is the incidence of osteolysis? We retrospectively reviewed 56 patients (69 hips) who underwent THA for femoral head ON with a cementless anatomic stem proximally coated with hydroxyapatite. Four patients (four hips) were lost to followup and 16 patients (19 hips) died. In the remaining 36 patients (46 hips) the minimum followup was 10 years (mean, 11.2 years; range, 10–13 years). The mean age at operation was 48.6 years. The average Harris hip score at last followup was 87 points. Worst-case survivorship was 58.1% at 13 years and best-case was 93.3%. The average linear wear of the polyethylene liner was 2.02 mm and the average annual wear was 0.18 mm per year. Thirty-seven hips (80%) had femoral osteolysis and 14 (30%) had acetabular osteolysis. One patient who had extensive femoral osteolysis and stem loosening was revised at 11.2 years postoperatively. The high rates of polyethylene wear and osteolysis are of concern.
Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-008-0202-y
PMCID: PMC2311464  PMID: 18327627
22.  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
23.  Distal locking stem for revision femoral loosening and peri-prosthetic fractures 
International Orthopaedics  2010;35(2):275-282.
Revision total hip arthroplasty in the setting of a large proximal femoral deficiency or a peri-prosthetic fracture remains a challenging problem. We describe the development, surgical technique and the use of cementless revision stems with distal inter-locking screws to provide immediate stability of the femoral implant. Results were assessed in a large multicentre French study conducted with the french hip and knee surgery society (SFHG). We retrospectively reviewed 725 revisions using interlocking stems from 14 French orthopaedic departments. Seven different stems were used in this series. In-patient records were retrieved, and in addition to demographic data the indication for revision, the preoperative and postoperative PMA and Harris hip scores were documented. The bone deficiency was classified on the basis of the French National Orthopaedic Meeting (SOFCOT) classification. Intraoperative complications and problems if any were retrieved from operative notes. Clinical status and radiographs at the final follow-up were evaluated, paying special attention to the metaphyseal filling index. Average follow-up was 4.5 years. As for the clinical results, the mean Harris hip score at last follow-up was 81. Therefore, it increased by an average of 31 points. Bone reconstruction was assessed on the cortico-medullary index in the metaphyseal area and at mid-shaft increasing from 36 to 45 and 54 to 63, respectively. Radiologically, 637 implants were stable, and 40 demonstrated subsidence. Forty-eight implants have been revised. We found a significant relation between the metaphyseal filling index, the stability of the stem and the quality of bone reconstruction. Results were analysed with respect to three groups of stems: group 1 was a straight, partially HA-coated implant; group 2 was a curved, fully HA-coated implant; and group 3 was a curved, partially-coated implant. Group 1 showed a significantly higher rate of failure when compared with the others types of implants. Group 2 had better functional results than group 3, which in turn reported better results than group 1. With regard to implant fixation, group 2 had significantly better results. Both groups 2 and 3 induced less thigh pain than group 1. The distal interlocking stem has shown promising results for femoral revisions. The advantages are initial axial and rotational stability and consistent bony in-growth owing to hydroxyapatite coating. Distal locked stems are mainly indicated to treat complex femoral revision with severe bone loss and peri-prosthetic fractures.
doi:10.1007/s00264-010-1182-6
PMCID: PMC3032103  PMID: 21184221
24.  The effect of adding tobramycin to Simplex P cement on femoral stem micromotion as measured by radiostereometric analysis 
Acta Orthopaedica  2012;83(2):115-120.
Background
Previous in vitro research on addition of antibiotics to bone cement has found no statistically significant deterioration in mechanical properties. However, no clinical studies have compared the performance of tobramycin-laden bone cement with that of standard bone cement (Simplex P).
Patients and Methods
23 patients (25 hips) were randomized to receive an Exeter (Stryker Orthopaedics) femoral stem cemented with either Simplex P (standard) or Simplex T (tobramycin-laden) cement. There were 2 years of follow-up, with scheduled radiostereometric (RSA) examinations.
Results
All stems migrated distally and showed some degree of retroversion. No clinically significant differences in stem subsidence or retroversion were found between the Simplex T and Simplex P cement groups after 2 years. Overall subsidence was less than in previous studies, probably due to a postponed initial post-surgical examination. Rates of subsidence in both cement groups were consistent with those from previous studies of Exeter stems.
Interpretation
Subsidence of the femoral stem after 2 years was similar in the Simplex T (tobramycin-laden) and Simplex P (standard) groups.
doi:10.3109/17453674.2011.652885
PMCID: PMC3339523  PMID: 22248163
25.  Reverse hybrid and cemented hip replacement compared using radiostereometry and dual-energy X-ray absorptiometry 
Acta Orthopaedica  2012;83(6):592-598.
Background and purpose
Total hip replacement (THR) with a reverse hybrid (RH), a combination of a cemented polyethylene cup and a cementless femoral stem, has been increasingly used in Scandinavia. In a randomized trial, we compared an RH THR with a proximal hydroxyapatite- (HA-) coated stem to a conventional cemented THR. Both groups received the same polyethylene cup.
Patients and methods
51 patients (52 hips) were included. Radiostereometry (RSA) and dual-energy X-ray absorptiometry (DEXA) were performed postoperatively and after 6, 12, and 24 months. 42 patients (43 hips) were followed for 2 years.
Results
Mean cup rotation around the x-axis was 0.13° for the cemented group and –0.24° for the RH group (p = 0.03). Cup migration in the other axes, and stem migration and wear were similar between the 2 study groups. Bone remodeling around the cup was also similar between the groups. Bone loss in Gruen zone 1 was 18% for the cementless stems, as compared to an increase of 1.4% for the cemented ones (p < 0.001). Bone loss was similar in the other Gruen zones. Harris hip score and Oxford hip score were similar pre- and postoperatively in the 2 groups.
Interpretation
In the present study, RH THR with a cementless hydroxyapatite-coated stem and conventional cemented THR did not show any major differences regarding stem migration and bone loss after 2 years of follow-up.
doi:10.3109/17453674.2012.742393
PMCID: PMC3555444  PMID: 23116437

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