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Bone & Joint Research
Vol. 8, Issue 7 | Pages 313 - 322
1 Jul 2019
Law GW Wong YR Yew AK Choh ACT Koh JSB Howe TS

Objectives. The paradoxical migration of the femoral neck element (FNE) superomedially against gravity, with respect to the intramedullary component of the cephalomedullary device, is a poorly understood phenomenon increasingly seen in the management of pertrochanteric hip fractures with the intramedullary nail. The aim of this study was to investigate the role of bidirectional loading on the medial migration phenomenon, based on unique wear patterns seen on scanning electron microscopy of retrieved implants suggestive of FNE toggling. Methods. A total of 18 synthetic femurs (Sawbones, Vashon Island, Washington) with comminuted pertrochanteric fractures were divided into three groups (n = 6 per group). Fracture fixation was performed using the Proximal Femoral Nail Antirotation (PFNA) implant (Synthes, Oberdorf, Switzerland; n = 6). Group 1 was subjected to unidirectional compression loading (600 N), with an elastomer (70A durometer) replacing loose fracture fragments to simulate surrounding soft-tissue tensioning. Group 2 was subjected to bidirectional loading (600 N compression loading, 120 N tensile loading), also with the elastomer replacing loose fracture fragments. Group 3 was subjected to bidirectional loading (600 N compression loading, 120 N tensile loading) without the elastomer. All constructs were tested at 2 Hz for 5000 cycles or until cut-out occurred. The medial migration distance (MMD) was recorded at the end of the testing cycles. Results. The MMDs for Groups 1, 2, and 3 were 1.02 mm, 6.27 mm, and 5.44 mm respectively, with reliable reproduction of medial migration seen in all groups. Bidirectional loading groups showed significantly higher MMDs compared with the unidirectional loading group (p < 0.01). Conclusion. Our results demonstrate significant contributions of bidirectional cyclic loading to the medial migration phenomenon in cephalomedullary nail fixation of pertrochanteric hip fractures. Cite this article: G. W. Law, Y. R. Wong, A. K-S. Yew, A. C. T. Choh, J. S. B. Koh, T. S. Howe. Medial migration in cephalomedullary nail fixation of pertrochanteric hip fractures: A biomechanical analysis using a novel bidirectional cyclic loading model. Bone Joint Res 2019;8:313–322. DOI: 10.1302/2046-3758.87.BJR-2018-0271.R1


The Journal of Bone & Joint Surgery British Volume
Vol. 84-B, Issue 8 | Pages 1121 - 1125
1 Nov 2002
Trail IA Nuttall D

We have performed a clinical and radiological analysis of 105 shoulder arthroplasties in patients with rheumatoid arthritis. The clinical results showed improvements in the Constant-Murley and Association of Shoulder and Elbow Surgeons score of 21 and 35, respectively. Both were statistically significant (p < 0.001). This improvement was maintained over a period of 8.8 years. There was no statistically significant difference in the scores after hemiarthroplasty and those after total arthroplasty. The presence of an intact rotator cuff was associated with improved function in both groups. In spite of the use of an uncemented humeral stem, no implant was radiologically loose or at risk. There was lucency in a single zone in 14 implants. One glenoid component was at risk and 16 had lucency in a single zone. There was, however, a significant difference in the amount of lucency which was associated with pegged and keeled glenoid components (p = 0.005). In the group with hemiarthroplasty, two or more years after surgery there was superior migration of the humeral component by more than 5 mm in 18 shoulders (28%) and medial migration by more than 2 mm in eight (16%). Both superior and medial migration had an effect on the outcome. Revision was undertaken in four patients for persistent pain relating to medial migration. With revision taken as the endpoint for survival after eight years, 92% were found to be still in situ


The Bone & Joint Journal
Vol. 100-B, Issue 1 | Pages 101 - 108
1 Jan 2018
Stevenson JD Kumar VS Cribb GL Cool P

Aims. Dislocation rates are reportedly lower in patients requiring proximal femoral hemiarthroplasty than for patients undergoing hip arthroplasty for neoplasia. Without acetabular replacement, pain due to acetabular wear necessitating revision surgery has been described. We aimed to determine whether wear of the native acetabulum following hemiarthroplasty necessitates revision surgery with secondary replacement of the acetabulum after proximal femoral replacement (PFR) for tumour reconstruction. Patients and Methods. We reviewed 100 consecutive PFRs performed between January 2003 and January 2013 without acetabular resurfacing. The procedure was undertaken in 74 patients with metastases, for a primary bone tumour in 20 and for myeloma in six. There were 48 male and 52 female patients, with a mean age of 61.4 years (19 to 85) and median follow-up of two years (interquartile range (IQR) 0.5 to 3.7 years). In total, 52 patients presented with a pathological fracture and six presented with failed fixation of a previously instrumented pathological fracture. Results. All patients underwent reconstruction with either a unipolar (n = 64) or bipolar (n = 36) articulation. There were no dislocations and no acetabular resurfacings. Articular wear was graded using the criteria of Baker et al from 0 to 3, where by 0 is normal; grade 1 represents a narrowing of articular cartilage and no bone erosion; grade 2 represents acetabular bone erosion and early migration; and grade 3 represents protrusio acetabuli. Of the 49 patients with radiological follow-up greater than one year, six demonstrated grade 1 acetabular wear and two demonstrated grade 2 acetabular wear. The remainder demonstrated no radiographic evidence of wear. Median medial migration was 0.3 mm (IQR -0.2 to 0.7) and superior migration was 0.3 mm (IQR -0.2 to 0.6). No relationship between unipolar versus bipolar articulations and wear was evident. Conclusion. Hemiarthroplasty PFRs for tumour reconstruction eliminate joint instability and, in the short to medium term, do not lead to native acetabular wear necessitating later acetabular resurfacing. Cite this article: Bone Joint J 2018;100B:101–8


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_III | Pages 276 - 276
1 Sep 2005
de Beer M Niksch N
Full Access

After many patients, some of whom were unexpectedly young, had presented with medial migration of the hemi-prosthetic head and erosion of the glenoid, we decided 2 years ago to do preoperative DEXA on all shoulder replacement patients. The aim was first to determine normal bone mineral density (BMD) of the glenoid and secondly to predict which patients would be at risk. We used the same DEXA method as for the hip. The glenoid was divided into three areas, numbered R1, R2 and R3, and we determined BMD in each of them. Preliminary studies showed that patients fell into two groups. In one, BMD in the R2 and R3 areas was in the range 0.3 to 0.5. Most often the patients in this group were younger or had acute trauma and the contralateral shoulder was not pathological. BMD in the other group was in the range 0.9 to 1.3. Nearly all patients with OA of the shoulder fell into this group. In this ongoing study, patients are followed up annually with clinical examination and standard radiographs. Follow-up to date has only been 2 years. So far no medial migration of the hemi-prosthetic head has been noted in patients in the group with BMD between 0.9 to 1.3


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_II | Pages 135 - 135
1 Feb 2004
De Lucas-Villarrubia JC Lòpez-Franco M Lòpez-Martín N De Miguel-Herrero I Pascual R De Lucas-García JC
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Introduction and Objectives: Acetabular bone defects in hip replacement therapy present difficulties in terms of achieving stable, long-lasting fixation of the implant. Various surgical techniques exist to correct this problem. In this study we analysed the clinical and radiographic progression of a series of patients treated with fragmented grafts using the X-Change acetabular revision method. Materials and Methods: From November 1988 to February 1998, 24 patients were treated, with an average age of 64.5 (±7) at the time of surgery. Patients were evaluated clinically preoperatively and were evaluated using the Harris scale at the end of the follow-up period. Defects were classified according to Paprosky’s classification of acetabular bone defects. Radiographic studies were used to evaluate upward and medial migration of the acetabular component and to look for signs of loosening. Follow-up time was a minimum of 12 months, with an average of 56.2 months. Results: Average score on the Harris scale went from 49.7 points (±12.9) preoperatively to 88.2 points (±14.1) on follow-up. There was no graft incorporation in 5 patients (20%). There were 3 infections, 2 prosthetic dislocations, and one case of pulmonary thromboembolism. Upward migration of the cup (from the upper obturator line) was 0.48 cm (±0.72) postoperatively and 0.48 cm (±0.84) at follow-up. Medial migration (measured from Kohler’s line) was −0.16 cm (±0.50) postoperatively and −0.09 cm (±0.56) on follow-up. Cup angle (measured at the anteroposterior plate of the pelvis) changed from 48.9° (±5°) to 56° (±7°) at the conclusion of the follow-up period. Discussion and Conclusions: This reconstructive technique provides stable, long-lasting fixation of the implant with complication rates similar to those described in the literature. We consider it a useful technique in the management of this type of defect, particularly in young patients who need to recover acetabular bone stock


The Bone & Joint Journal
Vol. 106-B, Issue 5 Supple B | Pages 47 - 53
1 May 2024
Jones SA Parker J Horner M

Aims

The aims of this study were to determine the success of a reconstruction algorithm used in major acetabular bone loss, and to further define the indications for custom-made implants in major acetabular bone loss.

Methods

We reviewed a consecutive series of Paprosky type III acetabular defects treated according to a reconstruction algorithm. IIIA defects were planned to use a superior augment and hemispherical acetabular component. IIIB defects were planned to receive either a hemispherical acetabular component plus augments, a cup-cage reconstruction, or a custom-made implant. We used national digital health records and registry reports to identify any reoperation or re-revision procedure and Oxford Hip Score (OHS) for patient-reported outcomes. Implant survival was determined via Kaplan-Meier analysis.


The Bone & Joint Journal
Vol. 106-B, Issue 5 Supple B | Pages 66 - 73
1 May 2024
Chaudhry F Daud A Greenberg A Braunstein D Safir OA Gross AE Kuzyk PR

Aims

Pelvic discontinuity is a challenging acetabular defect without a consensus on surgical management. Cup-cage reconstruction is an increasingly used treatment strategy. The present study evaluated implant survival, clinical and radiological outcomes, and complications associated with the cup-cage construct.

Methods

We included 53 cup-cage construct (51 patients) implants used for hip revision procedures for pelvic discontinuity between January 2003 and January 2022 in this retrospective review. Mean age at surgery was 71.8 years (50.0 to 92.0; SD 10.3), 43/53 (81.1%) were female, and mean follow-up was 6.4 years (0.02 to 20.0; SD 4.6). Patients were implanted with a Trabecular Metal Revision Shell with either a ZCA cage (n = 12) or a TMARS cage (n = 40, all Zimmer Biomet). Pelvic discontinuity was diagnosed on preoperative radiographs and/or intraoperatively. Kaplan-Meier survival analysis was performed, with failure defined as revision of the cup-cage reconstruction.


Bone & Joint Research
Vol. 13, Issue 12 | Pages 716 - 724
4 Dec 2024
Cao S Chen Y Zhu Y Jiang S Yu Y Wang X Wang C Ma X

Aims

This cross-sectional study aimed to investigate the in vivo ankle kinetic alterations in patients with concomitant chronic ankle instability (CAI) and osteochondral lesion of the talus (OLT), which may offer opportunities for clinician intervention in treatment and rehabilitation.

Methods

A total of 16 subjects with CAI (eight without OLT and eight with OLT) and eight healthy subjects underwent gait analysis in a stair descent setting. Inverse dynamic analysis was applied to ground reaction forces and marker trajectories using the AnyBody Modeling System. One-dimensional statistical parametric mapping was performed to compare ankle joint reaction force and joint moment curve among groups.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 214 - 214
1 Sep 2012
Beaulé P White C Lopez-Castellaro J Kim P
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Introduction. Although femoral neck fractures remain a concern in short term failures for hip resurfacing, acetabular component position and fixation are increasingly being recognized as causes of mid term failures for hip resurfacing. This study aimed to evaluate the migration pattern of a cobalt chrome, beaded acetabular component for a metal on metal hip resurfacing. Methods. 130 patients underwent metal on metal hip resurfacing: 66 hips in 60 patients had sufficient films to be included in this analysis. Forty-eight patients were male and 12 were female, with a mean age of 50 (range, 32–66). Ninety-five percent of the procedures were performed for osteoarthritis. In all cases acetabular migration was measured both vertically and horizontally, on serial radiographs using the computer-assisted Ein Bild Röntgen Analyse method. A minimum of three comparable radiographs is necessary for calculating the migration curves. We scored medial migration as negative horizontal movement. Results. At a mean follow up 25.3 months (24–36 months), each hip had an average of 5.1 radiographs for analysis. 12.5% of the cups showed more than 1 mm migration in the medial-lateral axis and 45.3% more than 1 mm in the vertical axis. 23% of the cups showed a combined migration of greater than 2 mm in the observation period. Two of these cases required revision for aseptic loosening at 34 months. Discussion and Conclusion. Previous studies have shown EBRA to have an excellent sensitivity and positive predictive value for mid to long term cup failure. This data raises concern about the initial stability if this acetabular component. Continued follow-up is needed to monitor the longer term survival of this implant


The Journal of Bone & Joint Surgery British Volume
Vol. 71-B, Issue 3 | Pages 447 - 451
1 May 1989
Wetherell R Amis A Heatley F

Using dried bones which could be tilted and rotated, we assessed the accuracy of published radiographic methods for measuring the migration of prosthetic acetabular components and compared the results with a new method. The new line linking acetabular margins was significantly more accurate for proximal migration than the teardrop, the sacroiliac line or the sacroiliac-symphysis line. For medial migration, a new line tangential to the brim and through the horizontal mid-point of the obturator foramen was more accurate than Kohler's line, the ilio-ischial line or the iliopubic line. In combination, the two new lines can give a more accurate assessment of acetabular erosion than previous methods, since they are less affected by the differences in rotation commonly found in a series of radiographs


The Journal of Bone & Joint Surgery British Volume
Vol. 85-B, Issue 8 | Pages 1114 - 1119
1 Nov 2003
Elke R Berli B Wagner A Morscher EW

The need for supplementary screw fixation in acetabular revisions is still widely debated. We carried out 439 acetabular revisions over an eight-year period. In 171 hips with contained or small segmental defects, the Morscher press-fit cup was used. These revisions were followed prospectively. No screws were used for additional fixation. A total of 123 hips with a mean follow-up of 7.4 years (5 to 10.5) were available for clinical and radiological review. There was no further revision of a press-fit cup for aseptic loosening. Radiological assessment revealed osteolysis in three hips. Of the original 171 hips there was cranial and medial migration of up to 6 mm at two years in 44 (26%). No further migration was seen after the second post-operative year. Acetabular revision without screws is possible with excellent medium-term results in well selected patients


The Journal of Bone & Joint Surgery British Volume
Vol. 76-B, Issue 6 | Pages 912 - 917
1 Nov 1994
Karrholm J Borssen B Lowenhielm G Snorrason F

Roentgen stereophotogrammetry was used to measure the migration of the centre of the femoral head in 84 cemented Lubinus SP I hip arthroplasties (58 primary operations, 26 revisions). Four to seven years later, seven femoral components had been revised because of painful loosening. These implants showed greater subsidence, medial migration and posterior migration during the first two postoperative years than did the hips which had not been revised. Six months after operation, subsidence of more than 0.33 mm combined with a total migration of more than 0.85 mm predicted an increased risk of subsequent revision; the amount of subsidence at two years was an even better predictor. The probability of revision was greater than 50% if the subsidence at two years was 1.2 mm or more


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XLIII | Pages 53 - 53
1 Sep 2012
Al-Maiyah M Chuter G Ramaskandhan J Siddique M
Full Access

Introduction. The standard practice of uncomplicated total ankle replacement (TAR) involves postoperative immobilisation. Periprosthetic fracture is a well-recognised complication following ankle arthroplasty. It occurs predominantly as a stress reaction on the medial tibial metaphysis during the postoperative rehabilitation period. Occasionally it occurs during surgery. We present fractures from a single-centre series of Mobility TARs. Materials and Methods. We have 133 TARs with 3 to 48 months' follow-up. 28 patients were excluded for the following reasons: other major procedure performed concurrently (osteotomy or tendon transfer), custom prosthesis, revision surgery, fusion conversions, or patients involved in a separate RCT (n = 16). We do not routinely immobilise patients postoperatively but allow partial to full weight-bearing as able. Outcome scores were compared to those without fractures. Results. 105 patients were included in the study. Nine (8.6%) patients sustained a periprosthetic fracture with no history of significant trauma. One of these was intraoperative; this was a posterior tibial fracture noticed on postoperative radiographs. The remainder (n = 8) were tibial metaphyseal stress fractures, all occurring within the first three months, most (n = 6) within six weeks. One occurred on the sixth post-op day and was managed in cast. Seven were asymptomatic at diagnosis and managed nonoperatively; one was fixed at three months due to radiological medial migration of the talus and one was fixed at seven months due to progression to symptomatic non-union. The remainder united. Between those with and without fractures, there was no significant difference in age (mean 61.4 vs. 62.1, p = 0.387), diagnosis leading to arthroplasty (OA, RA, PTOA), or outcome scores (12 months: 83 vs. 78, p = 0.237). Conclusion. Periprosthetic fracture remains a significant complication of total ankle arthroplasty. However, in our series, they do not lead to increased morbidity or worse outcome scores than patients without fractures and most can be managed nonoperatively


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 100 - 100
1 Sep 2012
Chuter G Ramaskandhan J Siddique M
Full Access

Introduction. The standard practice of uncomplicated total ankle replacement (TAR) involves post-operative immobilisation. Periprosthetic fracture is a well-recognised complication following ankle arthroplasty. It occurs predominantly as a stress reaction on the medial tibial metaphysis during the post-operative rehabilitation period. Occasionally it occurs during surgery. We present fractures from a single-centre series of Mobility TARs. Materials and Methods. We have 133 TARs with 3 to 48 months' follow-up. 28 patients were excluded for the following reasons: other major procedure performed concurrently (osteotomy or tendon transfer), custom prosthesis, revision surgery, fusion conversions, or patients involved in a separate RCT (n = 16). We do not routinely immobilise patients post-operatively but allow partial to full weight-bearing as able. Outcome scores were compared to those without fractures. Results. 105 patients were included in the study. Nine (8.6%) patients sustained a periprosthetic fracture with no history of significant trauma. One of these was intra-operative; this was a posterior tibial fracture noticed on post-operative radiographs. The remainder (n = 8) were tibial metaphyseal stress fractures, all occurring within the first three months, most (n = 6) within six weeks. One occurred on the sixth post-op day and was managed in cast. Seven were asymptomatic at diagnosis and managed non-operatively; one was fixed at three months due to radiological medial migration of the talus and one was fixed at seven months due to progression to symptomatic non-union. The remainder united. Between those with and without fractures, there was no significant difference in age (mean 61.4 vs. 62.1, p = 0.387), diagnosis leading to arthroplasty (OA, RA, PTOA), or outcome scores (12 months: 83 vs. 78, p = 0.237). Conclusion. Periprosthetic fracture remains a significant complication of total ankle arthroplasty. However, in our series, they do not lead to increased morbidity or worse outcome scores than patients without fractures and most can be managed non-operatively


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_III | Pages 319 - 319
1 Mar 2004
JosŽ Martinez M Bonay E Pernal C
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CLS Spotorno cotyle consists of an expansible hemispheric external component with troncoconic internal thin thread of Protasul Titanium. It also has a polyethylene UHMW internal threaded element which adapts prosthesic femoral heads (28–32 mm of diameter). The implant procedure is technically simple. First of all, the acetabulum is prepared by milling the cartilaginous surface with hemispheric mills. The external element is inserted pressthorn;t, later it is expanded with a troncoconic thread, the high density polyethylene is threaded inside the expanded component. The aim of this comunication is to expose the clinical and radiological outcome of 50 patients whom a CLS Spotorno expansible cotyle were implanted with a mean clinical follow up of 14 years. The indications are exposed considering the age, cotyle morphology and bone quality. The evaluation included both clinical and radiographic parameter. Test of Postel and Merle DñAubigne were assessed for this clinical outcome. Radiological evaluation included: Acetabular angle desviation, periprosthesic osteolysis, proximal and medial migration of the cotyle and polyethylene wear. The primary stability of the acetabular stems were found excellent. Good osteointegration and biocompatibility were demostrated by serial radiographic and funtional scores. We also present the surgical procedure, the complications and the conclusions of the study


Bone & Joint Open
Vol. 3, Issue 3 | Pages 268 - 274
21 Mar 2022
Krishnan H Eldridge JD Clark D Metcalfe AJ Stevens JM Mandalia V

Recognized anatomic variations that lead to patella instability include patella alta and trochlea dysplasia. Lateralization of the extensor mechanism relative to the trochlea is often considered to be a contributing factor; however, controversy remains as to the degree this contributes to instability and how this should be measured. As the tibial tuberosity-trochlear groove (TT-TG) is one of most common imaging measurements to assess lateralization of the extensor mechanism, it is important to understand its strengths and weaknesses. Care needs to be taken while interpreting the TT-TG value as it is affected by many factors. Medializing tibial tubercle osteotomy is sometimes used to correct the TT-TG, but may not truly address the underlying anatomical problem. This review set out to determine whether the TT-TG distance sufficiently summarizes the pathoanatomy, and if this assists with planning of surgery in patellar instability.

Cite this article: Bone Jt Open 2022;3(3):268–274.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_III | Pages 475 - 475
1 Sep 2009
Downing M Munro N Duthie R Hutchison J Ashcroft G
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Introduction: Impaction allografting is an established method for restoring deficient bone during revision arthroplasty of the hip. Graft augmentation with synthetic materials has been proposed and evaluated experimentally. Our aim was to assess clinically whether migration and wear of implants with a synthetic graft mix would be equivalent to pure allograft. Materials and Methods: Patient inclusion criteria were: acetabular and or femoral defects from aseptically loosened primary THR undergoing cemented revision with impaction grafting; age 55–80 years; initial diagnosis of osteo arthritis; good health with reasonable daily activity level. Patients were randomized to receive either pure allograft or a 50% mixture with a porous hydroxyapatite material (Apapore60, Apatech, UK). Revision was with the Exeter stem, antibiotic Simplex cement (Stryker Howmedica Ltd), and Ogee cup (Depuy Int. Ltd., Leeds, UK). Tantalum markers were inserted into the pelvis, cup, femur, cement and graft in order to measure migration with radiostereometry (RSA). Patients received a sequence of RSA examinations up to 2 years. A total of 26 patients (18 for the femur) have been analysed. Results: At 2 years no significant differences were seen in cup wear, or migration of the cup, femoral and pelvic graft markers. Stem migration occurred mainly at the stem cement interface. The rate of distal migration for the femoral head was greater for pure allograft in the first year (p < 0.05), however this rate reduced significantly in year two. Higher medial migration in year one was observed for the proximal medial cement mantle for allograft (p < 0.05). Conclusions: Improved stability and normal cup wear were observed in a randomized clinical study for a synthetically augmented allograft. This agrees with experimental findings. 1. Longer follow up with increased patient numbers is recommended to confirm these findings


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_IV | Pages 555 - 555
1 Nov 2011
White C Castellaro JL Beaulé PE Kim P
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Purpose: Although femoral neck fractures remain a concern in terms of short term failures for hip resurfacing, acetabular component position and fixation are increasingly being recognized as causes of mid term failures for hip resurfacing. The purpose of our study was to evaluate the migration pattern of a cementless acetabular component for a metal on metal hip resurfacing. Method: Between January 2006 and June 2007, 130 patients underwent metal on metal hip resurfacing; 66 hips in 60 patients were included in this analysis. Forty-eight patients were male and 12 were female, with a mean age of 50 (range, 32–66). Ninety-five percent of the surgeries were performed for osteoarthritis. All surgeries were performed by two surgeons using the Conserve Plus (Wright Medical Technology, Memphis, TN) hip resurfacing system. The acetabular component is a monoblock cobalt chrome with a porous beaded surface for osteointegration. In all cases acetabular migration was measured both vertically and horizontally, on serial radiographs using the computer-assisted Ein Bild Röntgen Analyse (EBRA) method. A minimum of three comparable radiographs is necessary for calculating the migration curves. We scored medial migration as negative horizontal movement. Results: At a mean follow up 25.3 months (range, 24–36 months), each hip had an average of 5.1 radiographs for analysis. The software excluded two cases for poor comparability ending finally with 64 cases for the analysis. Eighty-seven point five per cent of the cups showed less than 1 mm migration in the medium-lateral axis and 54.7% less than 1 mm in the vertical axis. Seventy-seven percent of the cups showed a combined migration of less than 2 mm in the observation period, without radiolucencies, leaving 23% of the acetabular components with 2 mm or greater of component migration. One of these cases required revision for aseptic loosening at 34 months. Conclusion: In our study the majority of the acetabular components were stable with some of the migration observed secondary to lack of complete initial seating due to the rigidity of the shell. Krismer et al did report on the migration of the PCA shell (also a porous beaded cobalt-chrome shell) using EBRA, with 27.5% of the shells demonstrating > 1 mm of migration. Although hip resurfacing has only mid term followup, results have been good to excellent. Caution should still be maintained since the higher frictional torque generated by the larger femoral head size as well as the nanometer size particles could negatively affect long term fixation of the acetabular component


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_II | Pages 312 - 313
1 Jul 2008
Derbyshire B Porter M
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Introduction: Some reports have suggested an unacceptable failure rate of Elite Plus stem in the medium term. We have previously argued that other measurements must be made in addition to RSA in order to assess reasons for abnormal migrations. This 3-year RSA study of Elite Plus stems assessed the migration pattern and factors that influenced it. Method: Twenty five patients (23 OA, 2 RA, mean age 60.4 years (37–81)) underwent Elite Plus THR (single surgeon). A-P radiographs were assessed for cementing technique, and measurements (canal widths, stem orientation, cement thickness etc) were taken using CAD software. Activity score and BMI were also recorded. Multiple factors were assessed for correlation with the main components of migration. Results: One patient’s stem centroid migrated proximally (due to valgus rotation about the shoulder) and the mean subsidence of the others was 0.297 mm at 36 months. Mean internal rotation and posterior head migration (25 patients) at that time were: 1.42° (CI: 0.99° to 1.86°) and 0.801 mm (CI: 0.526 mm to 1.076 mm), neither being significantly different from migrations at 24 months. One patient’s stem migrated continuously. By 36 months, it had subsided 1.279 mm and internally rotated 4.2°. Some significant correlations (p < 0.05, rho > 0.6) were 3M and 36M subsidence with proximal-medial cement thickness; effective offset with 36M medial migration. Discussion: The one patient with continuous high migration had the highest activity level. This was corroborated by a wear measurement of 3.5 mm in the contralateral (Charnley) hip which had been in place for 9 years (assuming the head was not scratched). If RSA, 3 years postoperatively, can predict future outcome, the 4% failure rate is similar to the ten year results of the Charnley hip


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_I | Pages 27 - 27
1 Mar 2009
Zenz P Knechtel H Titzer-hochmaier G Schwägerl W
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Introduction: The Allofit cup is a hemispherical pressfit cup with a flattened pole for cementless implantation. Clinical use started in 1993 and we report our clinical and radiographic results of the first 100 cases. 75 hips of this group have been followed during the first 3 to 4 years using EBRA for migration analysis. These results also are presented. Material: Out of 100 hips 81 have been followed mith a mean of 10,1 years (9,8–11). 6 patients died, 11 did not show for follow up an 1 patient had a revision for deep infection with two-stage exchange meanwhile. The initial diagnosis was primary coxarthrosis in 63, rheumatoid arthritis in 10, congenital dislocation of the hip in 5 and necrosis of the femoral hed in 3. In all cases the cementless Alloclassic stem was used, as bearing material metasul was implanted in 73 and ceramic-polyethylene in 8 cases. Complications: For prolonged exsudation from the wound one soft tissue revision was necessary. 2 luxations were treated conservative. One early deep infection healed after synovectomy and irrigation, one late deep infection was cured by a two stage reimplantation. Results: The EBRA migration analysis after 3,6 years (2,3–4,2) showed cranial migration of 0,35 mm (0,2–0,6 mm), medial migration of 0,25 mm (0,10–0,40 mm) and a calculated total migration as a combination of both of 0,45 mm (0,22–0,72). Therefore at this time there was no evidence of early loosening or migration indicating later loosening. The preoperative Harris hip score was 53,13 pts (23–73), the postoperative score after 10 years 96,5 (78–100). Radiographic evaluation after 10 years showed no lucencies in 78 of 81 jpints. 3 hips had a lucent line of 1mm in zone III. We detected no signs of osteolysis, loosening or migration. No reoperations for any reason exept 2 septic cases have been performed yet. Summary: After 10 years the clinical and radiological results of this implant are very satisfying. These results confirm the early observations of a migration analysis performed 6 to 8 years before