Migration Of Acetabular Component Research Articles

Corroboration of coupled musculoskeletal model and finite element predictions with in vivo RSA migration of an uncemented acetabular component.

While finite element (FE) models have been used extensively in orthopedic studies, validation of their outcome metrics has been limited to comparison against ex vivo testing. The aim of this study was to validate FE model predictions of the initial cup mechanical environment against patient-matched in vivo measurements of acetabular cup migration using radiostereometric analysis (RSA). Tailored musculoskeletal and FE models were developed using a combination of three-dimensional(3D) motion capture data and clinical computerized tomography(CT) scans for a cohort of eight individuals who underwent primary total hip replacement and were prospectively enrolled in an RSA study. FE models were developed to calculate the mean modulus of cancellous bone, composite peak micromotion (CPM), composite peak strain (CPS) and percentage area of bone ingrowth. The RSA cup migration at 3 months was used to corroborate the FE output metrics. Qualitatively, all FE-predictedmetrics followed a similar rank order as the in vivo RSA3Dmigration data. The two cases with the lowest predicted CPM (<20 µm), lowest CPS (<0.0041), and high bone modulus (>917 MPa) were confirmed to have the lowest in vivo RSA 3D migration (<0.14 mm). The two cases with the largest predicted CPM (>80 µm), larger CPS (>0.0119) and lowest bone modulus (<472 MPa) were confirmed to have the largest in vivo RSA 3D migration (>0.78 mm). This study enabled the first corroboration between tailored musculoskeletal and FE model predictions with in vivo RSAcup migration. Investigation of additional patient-matched CT, gait, and RSA examinations may allow further development and validation of FE models.

THE IMPORTANCE OF PRESS-FIT AND THREE-POINT FIXATION IN TREATING LARGE ACETABULAR DEFECTS WITH POROUS TANTALUM COMPONENTS

First-time revision acetabular components have a 36% re-revision rate at 10 years in Australia, with subsequent revisions known to have even worse results. Acetabular component migration &gt;1mm at two years following revision THA is a surrogate for long term loosening. This study aimed to measure the migration of porous tantalum components used at revision surgery and investigate the effect of achieving press-fit and/or three-point fixation within acetabular bone.Between May 2011 and March 2018, 55 patients (56 hips; 30 female, 25 male) underwent acetabular revision THR with a porous tantalum component, with a post-operative CT scan to assess implant to host bone contact achieved and Radiostereometric Analysis (RSA) examinations on day 2, 3 months, 1 and 2 years. A porous tantalum component was used because the defects treated (Paprosky IIa:IIb:IIc:IIIa:IIIb; 2:6:8:22:18; 13 with pelvic discontinuity) were either deemed too large or in a position preventing screw fixation of an implant with low coefficient of friction. Press-fit and three-point fixation of the implant was assessed intra-operatively and on postoperative imaging.Three-point acetabular fixation was achieved in 51 hips (92%), 34 (62%) of which were press-fit. The mean implant to host bone contact achieved was 36% (range 9-71%). The majority (52/56, 93%) of components demonstrated acceptable early stability. Four components migrated &gt;1mm proximally at two years (1.1, 3.2, 3.6 and 16.4mm). Three of these were in hips with Paprosky IIIB defects, including 2 with pelvic discontinuity. Neither press-fit nor three-point fixation was achieved for these three components and the cup to host bone contact achieved was low (30, 32 and 59%).The majority of porous tantalum components had acceptable stability at two years following revision surgery despite treating large acetabular defects and poor bone quality. Components without press-fit or three-point fixation were associated with unacceptable amounts of early migration.

Uncemented total hip replacement with impaction bone grafting in protrusio acetabuli

Protrusio acetabuli is a central acetabular defect resulting from migration of femoral head medial to Kohler’s line. Idiopathic central displacement of femoral head within the acetabulum is quite rare. However, it may be seen in arthritic hips secondary to rheumatoid arthritis, ankylosing spondylitis, previous trauma, osteomalacia, etc. Primary Total Hip Replacement (THR) in such cases is difficult because of the deficient medial bone, decreased peripheral bony support to the acetabular component and proximal and medial migration of the joint centre. Several techniques described previously in the surgical management of protrusio acetabuli include cemented acetabular components with cement alone or in association with morselized bone graft to reconstruct the acetabulum. However, cement has high rates of migration and loosening of cemented acetabular components in young patients leads to more revision surgeries within the first decade of implantation. The purpose of the study is to describe the technique and results of using impacted morselized bone graft with a porous coated cementless acetabular component in patients with protrusio acetabuli.A total of 20 primary THR’s (10 unilateral and 5 bilateral) in 15 patients (8 females and 7 males) with protrusio acetabuli were performed between 2018 and 2021, out of which 4 had mild,7 had moderate and 9 had a severe grade of protrusion. A total of 10 hips were affected by rheumatoid arthritis,3 by ankylosing spondylitis and 7 had unknown etiology. After the surgery, all bone grafts had united by the sixth month with no perceptible change in acetabular component position in any case. The mean preoperative Harris Hip Score was 48 which improved to 82 at the latest follow-up. 45% had excellent,33% had good, and 22% had fair results. There was no dislocation. The use of impacted morselized autograft with a cementless porous acetabular component is a good technique of restoration of hip biomechanics and sound fixation in cases of protrusio acetabuli.

Acetabular Screw in Close Proximity to the Posterior Branch of the Internal Iliac Artery in Revision Hip Surgery with Intrapelvic Migration of Acetabular Component: Preoperative Placement of a Fogarty Catheter in the Internal Iliac Artery (Case Report).

Revision of an intrapelvic migration of the acetabular component of a total hip is a challenging surgery due to the risk of injury to the pelvic viscera. The primary concern is vascular injury due to the risk of mortality and limb loss. The researchers present one case where the acetabular screw was near the posterior branch of the internal iliac artery. A Fogarty catheter was placed in the internal iliac artery preoperatively, and the amount of fluid to inflate the catheter and completely block the artery was determined. The catheter was kept in a deflated condition. The hip reconstruction was performed, and there was no incidence of vascular injury during the procedure; hence, the Fogarty catheter was removed postsurgery. The placement of a Fogarty catheter in the at-risk vessel provides the freedom to proceed with the hip reconstruction through the standard approach. In case of an inadvertent event of a vascular injury, it can be inflated with the predetermined amount of saline to check the bleeding until the vascular surgeons take over the case.

Previous corrective osteotomies of femur and pelvis are a risk factor for complications following total hip arthroplasty in hip dysplasia

BackgroundModified anatomy of dysplastic hips, bone defects and previous operations make THA (total hip arthroplasty) in patients with hip dysplasia a technically challenging procedure. MethodsOne hundred and ten patients (mean 49.2 years of age, range 19–76, female:103, male:7) underwent 122 subsequent hip arthroplasties from 2012 to 2019. These patients were reviewed at least two years after THA. Plain radiography was used to determine Crowe classification of the affected hips. Fifty-three patients had an operation in childhood before THA was done (mean 47.0 years of age, standard deviation 8.3, range 19–62) and formed the “operated group”. Among these patients, there were Chiari pelvic osteotomies, periacetabular osteotomies, femoral osteotomies, greater trochanter distalizations and soft tissue operations. Fifty-seven were not operated in childhood (mean 52.3 years of age, standard deviation 10.9, range 19–76) and formed the “non operated group”. The functional status of the patients was assessed with the Oxford Hip Score (OHS). Results122 total hip arthroplasties were performed using uncemented femoral and acetabular components. There were 13 major complications identified. Ten were in the “operated group”, of which 5 needed revision surgery. Only 3 were in the “non operated group”, with no need for revision. Aseptic loosenings of the femoral component were seen in the patients that had femoral osteotomy done in childhood. Acetabular component migration and intrapelvic migration occurred due to the initial malposition and lack of osteointegration, thus requiring early revision after just 6 months. Other major complications were peroneal palsy, deep periprosthetic infection, severe trochanteritis and intraoperative femoral fracture. OHS was significantly higher in the “non operated group” 42.3 (10–48), opposed to 39.1 (10–48) in the “operated group” (p 0.017). ConclusionCorrective osteotomies in childhood are a risk factor for complications and lower medium-term survivorship of the THA in hip dysplasia patients.

Cemented acetabular components combined with trabecular metal augments provide excellent long-term survivorship for severe acetabular bone loss.

Acetabular bone loss is a challenging problem for revision hip surgeons. This study aimed to explore long-term outcomes of patients who have undergone cemented acetabular revision in conjunction with trabecular metal augmentation and impaction bone grafting in cases with significant segmental bone loss. All patients who underwent cemented acetabular revision requiring impaction bone grafting and trabecular metal augments with a minimum Paprosky score of 2B and minimum follow up of 5 years were identified. Pre- and postoperative WOMAC scores were compared. An assessment of pre- and postoperative hip centre of rotation was performed and compared to native centre of rotation. Immediate postoperative centre of rotation was then compared to radiographs at latest follow up to measure for migration of acetabular components. 42 patients were identified. Mean age was 53 years old with 7 males and 35 female patients. Mean follow-up was 9.5 years. Preoperative WOMAC score was 30 and there was an increase to 90 (p < 0.01) at latest follow-up. No hips were revised for loosening or infection. There was a mean improvement in centre of rotation of 6.80 mm (CI, 4.57-9.03 mm) which was significant (p < 0.00002). There was no change of position of centre of rotation from immediate postoperative radiographs and those at latest follow up (p = 0.3). Cemented acetabular components work well in conjunction with trabecular metal augments and impacted bone grafts in reconstructing complex acetabular defects. Together they provide immediate and long-term component stability, with excellent long-term clinical and radiological outcomes.

Acetabular Reconstruction Using Multiple Porous Tantalum Augments: Three-Quarter Football Augment

Reconstruction of a large acetabular bone defect is a complex problem in revision hip arthroplasty. The authors report a novel method of reconstructing an uncontained acetabular defect (Paprosky type IIIb) using multiple tantalum augments. A 73-year-old female patient presented to our institution with a chronically dislocated primary left total hip arthroplasty with radiographs demonstrating migration of acetabular component and formation of pseudoarthrosis within the left ilium. Extensive arthrolysis and anatomic reconstruction of the acetabular bone defect were performed using the novel method of multiple tantalum augments. Postoperatively, recovery was initially complicated by multiple dislocations requiring an exchange to an elevated liner, however subsequently achieved good function.

Correction to: Short‑term clinical and radiographic outcomes of total hip arthroplasty with PMPC‑grafted highly cross‑linked polyethylene liners against 32‑mm femoral heads

A correction to this paper has been published: https://doi.org/10.1007/s10047-021-01258-4

Short-term clinical and radiographic outcomes of total hip arthroplasty with PMPC-grafted highly cross-linked polyethylene liners against 32-mm femoral heads

We evaluated the clinical and radiographic outcomes of femoral head penetration and total hip arthroplasties with untreated and poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC)-grafted highly cross-linked polyethylene (HXLPE) acetabular liners against 26-, 28-, and 32-mm cobalt–chromium alloy femoral heads 3 years after the index surgery. Three combinations of the articulating surfaces were evaluated in the present study: untreated or PMPC-grafted HXLPE liner against 26- or 28-mm femoral heads (n = 16, 24) [control (26 or 28 mm) and PMPC (26 or 28 mm)] and PMPC-grafted HXLPE liner against 32-mm femoral heads (n = 64) [PMPC (32 mm)]. The clinical outcomes improved at 3 years postoperatively for the groups. No periprosthetic osteolysis or acetabular component migration was detected, and no revision surgery was performed among the groups. The steady-state wear rate of the PMPC (26 or 28 mm) group (0.021 mm/year) was lower than that of the control (26 or 28 mm) group (− 0.015 mm/year); the steady-state wear was under the clinical threshold. In contrast, the steady-state wear rate of the PMPC (32 mm) group (-0.006 mm/year) showed no significant difference when compared to that of the PMPC (26 or 28 mm) group (p < 0.01). The results obtained in the present study clearly demonstrate that PMPC-grafting onto an HXLPE surface improved the wear resistance of acetabular liners, even when coupled with larger femoral heads. Although further follow-up evaluations are required, PMPC-grafted HXLPE acetabular liners may be a promising approach to extend the longevity of artificial joints.

Vitamin E-doped total hip arthroplasty liners show similar head penetration to highly cross-linked polyethylene at five years: a multi-arm randomized controlled trial.

AimsThe most frequent indication for revision surgery in total hip arthroplasty (THA) is aseptic loosening. Aseptic loosening is associated with polyethylene liner wear, and wear may be reduced by using vitamin E-doped liners. The primary objective of this study was to compare proximal femoral head penetration into the liner between a) two cross-linked polyethylene (XLPE) liners (vitamin E-doped (vE-PE)) versus standard XLPE liners, and b) two modular femoral head diameters (32 mm and 36 mm).MethodsPatients scheduled for a THA were randomized to receive a vE-PE or XLPE liner with a 32 mm or 36 mm metal head (four intervention groups in a 2 × 2 factorial design). Head penetration and acetabular component migration were measured using radiostereometric analysis at baseline, three, 12, 24, and 60 months postoperatively. The Harris Hip Score, University of California, Los Angeles (UCLA) Activity Score, EuroQol five-dimension questionnaire (EQ-5D), and 36-Item Short-Form Health Survey questionnaire (SF-36) were assessed at baseline, three, 12, 36, and 60 months.ResultsOf 220 screened patients, 127 were included in this study. In all, 116 received the allocated intervention, and 94 had their results analyzed at five years. Head penetration was similar between liner materials and head sizes at five years, vE-PE versus XLPE was -0.084 mm (95% confidence interval (CI) -0.173 to 0.005; p = 0.064), and 32 mm versus 36 mm was -0.020 mm (95% CI -0.110 to 0.071; p = 0.671), respectively. No differences were found in acetabular component migration or in the patient-reported outcome measures.ConclusionNo significant difference in head penetration was found at five years between vE-PE and XLPE liners, nor between 32 mm and 36 mm heads.Cite this article: Bone Joint J 2020;102-B(10):1303–1310.

Highly Porous Tantalum Acetabular Components Without Ancillary Screws Have Similar Migration to Porous Titanium Acetabular Components With Screws at 2 Years: A Randomized Controlled Trial

BackgroundIt is proposed that highly porous coatings on acetabular components, such as a porous tantalum coating, provide adequate fixation without ancillary screw fixation in primary total hip arthroplasty (THA). However, tantalum acetabular components have been associated with higher rates of revision than other uncemented components in national registries. The aim of this randomized controlled trial is to determine whether the early migration of a solid-backed tantalum acetabular component was no greater than that of a titanium acetabular component with ancillary screw fixation that has proven good clinical results. MethodsSixty-six patients aged 40 to 64 years, with osteoarthritis and Charnley grade A or B activity grade and who underwent primary THA, were recruited into the trial. Patients were randomized intraoperatively to receive either the tantalum or titanium acetabular component. All patients received the same cemented polished tapered femoral stem, 28-mm cobalt-chromium femoral head, and highly cross-linked polyethylene liner. Acetabular component migration was measured using radiostereometric analysis at 4-6 days postoperatively and at 6 weeks, 3 months, 1 and 2 years following THA. ResultsThe mean proximal migration at 2 years for the tantalum cohort was 0.17 mm (95% confidence interval, 0.09-0.24) which was no greater than that of the titanium cohort which was 0.19 mm (0.07-0.32). Harris hip scores and functional activity scores were similar between groups. ConclusionThese results demonstrate that early stability can be achieved without ancillary screw fixation through the use of a highly porous high friction coating on a solid-backed modular acetabular component. Level of EvidenceLevel I.

Acetabular Component Migration Measured Using Radiostereometric Analysis Following Revision Total Hip Arthroplasty: A Scoping Review.

* Radiostereometric analysis (RSA) studies of acetabular component migration following revision total hip arthroplasty (THA) have a large variation in their methodology and reporting of results, and, therefore, they may not be directly comparable. Standardization of RSA reporting is recommended. * In our review of RSA studies, there was a trend for cemented acetabular components to have larger amounts of early proximal migration than uncemented acetabular components. Results regarding cemented and uncemented components should be reported separately. * Cohorts that addressed larger acetabular defects were associated with a larger amount of early migration. * Reporting the migration result at 1 and 2 years postoperatively may enable earlier identification of poorly performing implants.

Accuracy of EBRA-cup measurements after reconstruction of severe acetabular defects at revision THR.

Radiostereometric analysis (RSA) is the most accurate method of measuring component migration using radiographs but is restricted to use in prospective studies. Ein-Bild-Roentgen-analyze (EBRA)-Cup can be used retrospectively, but its accuracy to measure component migration following revision is unknown. This study aimed to determine the accuracy of EBRA-Cup measurements of uncemented acetabular component migration after revision total hip replacement (THR). The secondary aim was to compare the number of cases identified using EBRA-Cup and RSA as having proximally migrated above and below 1 mm at 2 years postoperatively. EBRA-Cup measurements were performed on plain antero-posterior pelvic radiographs taken at the same time as RSA radiographs in a prospective cohort of 53 hips undergoing acetabular revision. At 2 years, the mean difference between the RSA and EBRA-Cup measurements for 17 components used to treat pelvic discontinuity was 0.90 mm, significantly greater than the mean difference of 0.28 mm for 36 components without discontinuity (P = .0001). The mean difference between the RSA and EBRA-Cup measurements at 2 years for hips that were reconstructed with an acetabular component alone, 0.28 mm, was significantly lower than hips that were reconstructed with an acetabular component in combination with an augment and/or cage, 0.74 mm (P = .0005). In conclusion, EBRA-Cup can accurately measure migration of uncemented acetabular components used at revision THR. The presence of pelvic discontinuity, and addition of augments and cages, significantly influenced the accuracy of EBRA-Cup measurements. EBRA-Cup and RSA had good agreement on classification of components that migrated proximally above or below 1 mm at 2 years, with 100% sensitivity, and 87% specificity.

Early results of revision dual mobility uncemented cups with impaction autologous and synthetic bone graft composite in revision hip arthroplasty for cavitary acetabular defects: A retrospective case series

Background: The presence of cavitary acetabular defects can present a major challenge during revision hip arthroplasty. The purpose of this study was to retrospectively review the early clinical and radiographic outcomes of a dual-mobility, cementless acetabular shell system when combined with autologous or synthetic bone graft substitute composite in revision hip arthroplasty for cavitary acetabular defects. Methods: Fourteen revision hip arthroplasties for acetabular protrusion and cavitary acetabular defects were performed at our institutions between May, 2015 to June, 2016. A direct lateral approach was used for all patients. All patients were assessed with the Oxford Hip Score. Serial postoperative radiographs were assessed for signs of osseointegration and acetabular component migration. Failures were defined as gross acetabular component migration and deterioration of patient self-reported outcome score postoperatively. Results: After a mean follow-up of 28.9 mo, the Oxford Hip Score and hip pain scores were significantly improved (P≤0.01). Radiographically sufficient bone graft osseointegration was obtained in all patients with no detected acetabular component migration. Conclusions: This study showed good overall short-term functional and radiographic outcomes of the dual-mobility, uncemented acetabular shell system in combination with autologous or synthetic bone graft composite in revision hip arthroplasty for cavitary acetabular defects. Level of Evidence: Level IV.

STAGED SURGICAL RECONSTRUCTION OF MASSIVE PELVIC DEFECT

Purpose of the study — to illustrate on a particular clinical case an option of treatment for patients with severe pelvic defects by a staged surgery: vascularized bone grafting and revision arthroplasty using custom made implant produced by laser sintering based on layered 3D-visualisation. Material and Methods. Female, 61 years old, was admitted to clinic in 2016 with aseptic loosening of acetabular component and polyethylene insert wear following arthroplasty with total cementless prosthesis. Revision arthroplasty was made with hemispherical augment and anti-protrusion ring. On day 7th after the surgery a dislocation of prosthesis head, pubic bone fracture, migration of acetabular component and bone defect with pelvic discontinuity occurred due to trauma. To restore continuity of the pelvic ring and supportability of the lower limb the authors performed a staged multisession procedure: removal of prosthesis, free vascularized bone grafting by costal vascular pedicle graft and plating fixation of the pelvis. 6 months after the first stage a custom made prosthesis was implanted. Such prosthesis was produced based on a 3D pelvis reconstruction model by layered visualization and with evaluation of bone density on the Hounsfield scale and was printed on 3D-printer by laser sintering from LPW-TI64-GD23-TYPE5 titanium. Results. The authors did not observe any septic complications, dislocations and components migration in the early postoperative period. Function was assessed by Harris Hip Score. Scores prior to arthroplasty by a custom made implant was 12 points, one month postoperatively — 30 points, three months postoperatively — 51 points, six months postoperatively — 74 points. Life quality scores by SF-36 were reported as follows: prior to surgery РН — 21.32; МН — 40.92; one month postoperatively РН — 40.66; МН — 55.80; three months postoperatively РН — 52.14; МН — 57.81; six months postoperatively РН — 62.46; МН — 72.08. Conclusion. Vascularized bone autoplasty allows to restore pelvic continuity, and the use of custom made implants — to restore supportability of the lower limb and hip function in case of an extensive pelvic defect.

L’appui complet immédiat est-il possible en cas de fracture de l’arrière-fond acétabulaire au cours d’une arthroplastie totale de hanche ?

BackgroundA breach of the medial acetabular wall is a phenomenon seen frequently due to over-reaming during total hip arthroplasty (THA). The consequences of this issue are not fully understood particularly in cementless THA. A retrospective study was performed to answer whether: (1) immediate postoperative full-weight bearing in the presence of a medial acetabular wall breach after THA results in more short-term revisions of the acetabular component, (2) increases the risk for migration of the acetabular component? HypothesisImmediate full-weight bearing in the presence of a medial breach is not associated with an increased likelihood for acetabular-related revision surgery or migration of the cup. Patients and methodsIn this retrospective cohort study, consecutive patients (n=95; mean age 68±13 years; 67 female) who underwent THA with an uncemented acetabular component were identified and a retrospective chart review was performed (follow-up 23±17 months, range 6 to 79 months). The presence of a postoperative radiographic medial acetabular breach was documented and the need for revision surgery and the rate of acetabular component migration were assessed during follow-up. ResultsSome extent of radiographic medial acetabular wall breach was seen in 26/95 patients (27%). With regard to the primary outcome, 2/95 patients (2%) required revision surgery during follow up. All revision surgeries occurred in the group without a medial breach (p=0.280) for causes related to the femoral or the head components. Persistent pain was present in 1/26 patients (3.8%) in the medial breach group and 8/69 patients in the control group (11.6%; p=0.436). In the radiographic follow-up, (n=81), there was no significant difference between the control group and the medial breach group with regard to cup migration (Δ ilio-ischial overlap (distance between the ilio-ischial line and a parallel line tangential to the acetabular cup on AP views): −0.5±0.9mm (range, −2.9 to 0.8) vs. −0.3±1.7mm (range, −1.9 to 2.2), Δ overlap tangent (defined as the distance between the two crossings of ilio-ischial line and the acetabular component on AP views): −2.2±6.1mm (range, −21.4 to 0.0) vs. 0.4±6.9mm (range, −6.2 to 17.6). Similarly, according to variation in the ilio-ischial overlap distance between postoperative and follow-up on pelvic AP views, 0/56 hips (0%) had cup migration≥5mm in the control group versus 1/25 (4%) in the medial breach cohort (p=0.3). DiscussionIn this retrospective observation of patients with immediate postoperative full-weight bearing after THA, a radiographic breach of the medial acetabular wall was not associated with an increased risk for short-term revision surgery or radiographic migration at follow-up. According to the findings of this study and in the light of previous biomechanical studies, there is no clear evidence for postoperative partial-weight bearing in case of a medial breach as far as the surgeon feels that the acetabular component is stable. Level of evidenceIV, Retrospective cohort study.

Retrospective comparative study of fracture neck of femur treated with Uni polar Vs bipolar hemiarthroplasty

Background and Objective: Intracapsular femoral neck fractures are common in the elderly population. To avoid the poor outcome of internal fixation and for early mobilization, hemiarthroplasty is performed. However, there is inadequate evidence to support the choice between unipolar or bipolar hemiarthroplasty. The aim of this study was to compare the outcome of unipolar with the bipolar prosthesis in geriatric patients especially in rural population of kolar. Methods: sixty patients above 60 years of age and an acute displaced fracture of the femoral neck were randomly allocated to treatment by either unipolar or bipolar hemiarthroplasty, in the Department of Orthopaedics, between September 2009 and October 2012. Functional outcome was assessed and compared using Harris hip score and radiological parameters with a follow-up of one year. Results: The two groups of patients with mean age of 68.3% in bipolar group and 69.9% in unipolar group did not differ in their pre-injury characteristics and perioperative parameters. There was no significant difference between a Moore’s and a bipolar prosthesis regarding hip pain, functional hip scores, rates of acetabular erosion, component migration, revision surgery and complications rates. Conclusion: Use of the more expensive bipolar prosthesis in elderly and premorbidly ambulant patient is not justified especially in rural population.

Medial acetabular wall breach in total hip arthroplasty - is full-weight-bearing possible?

A breach of the medial acetabular wall is a phenomenon seen frequently due to over-reaming during total hip arthroplasty (THA). The consequences of this issue are not fully understood particularly in cementless THA. A retrospective study was performed to answer whether: immediate postoperative full-weight-bearing in the presence of a medial acetabular wall breach after THA results in more short-term revisions of the acetabular component, and increases the risk for migration of the acetabular component? Immediate full-weight-bearing in the presence of a medial breach is not associated with an increased likelihood for acetabular-related revision surgery or migration of the cup. In this retrospective cohort study, consecutive patients (n=95; mean age 68±13 years; 67 female) who underwent THA with an uncemented acetabular component were identified and a retrospective chart review was performed (follow-up 23±17 months, range 6 to 79 months). The presence of a postoperative radiographic medial acetabular breach was documented and the need for revision surgery and the rate of acetabular component migration were assessed during follow-up. Some extent of radiographic medial acetabular wall breach was seen in 26/95 patients (27%). With regard to the primary outcome, 2/95 patients (2%) required revision surgery during follow-up. All revision surgeries occurred in the group without a medial breach (p=0.280) for causes related to the femoral or the head components. Persistent pain was present in 1/26 patients (3.8%) in the medial breach group and 8/69 patients in the control group (11.6%; p=0.436). In the radiographic follow-up (n=81), there was no significant difference between the control group and the medial breach group with regard to cup migration (Δ ilio-ischial overlap [distance between the ilio-ischial line and a parallel line tangential to the acetabular cup on AP views]: -0.5±0.9mm [range, -2.9 to 0.8] vs. -0.3±1.7mm [range, -1.9 to 2.2], Δ overlap tangent [defined as the distance between the two crossings of ilio-ischial line and the acetabular component on AP views]: -2.2±6.1mm [range, -21.4 to 0.0] vs. 0.4±6.9mm [range, -6.2 to 17.6]). Similarly, according to variation in the ilio-ischial overlap distance between postoperative and follow-up on pelvic AP views, 0/56 hips (0%) had cup migration ≥ 5mm in the control group versus 1/25 (4%) in the medial breach cohort (p=0.3). In this retrospective observation of patients with immediate postoperative full-weight-bearing after THA, a radiographic breach of the medial acetabular wall was not associated with an increased risk for short-term revision surgery or radiographic migration at follow-up. According to the findings of this study and in the light of previous biomechanical studies, there is no clear evidence for postoperative partial weight-bearing in case of a medial breach as far as the surgeon feels that the acetabular component is stable. IV, Retrospective cohort study.

Neglected posterior acetabular wall fracture managed with uncemented total hip arthroplasty with posterior wall reconstruction by femoral head autograft: a case report

&lt;p class="abstract"&gt;Total hip arthroplasty (THA) poses several challenges as a treatment option for acetabular fracture especially in the setting of a neglected fracture. The potential technical challenges of THA include the altered anatomy and hip centre, acetabular bone deficit, difficulty in achieving long-term fixation of the acetabular shell and risk of nerve injury. In our case, a forty two years old, male labrourer presented with a five months old injury, which was previously managed only conservatively. Preoperative evaluation revealed displaced posterior wall acetabulum with superiorly migrated femur head with flattened contour. We managed the case with uncemented THA. The acetabular defect was addressed using the femoral head autograft which was secured with screws. On three months follow up, radiographical evalution showed good graft consolidation without any acetabular component migration and functionally a Harris hip score of 76. Thus, in case of neglected acetabular fractures, with high probability of post traumatic arthritis to develop, THA remains the preferred choice of management. Albeit challenging to perform, THA provides effective way to decrease pain, improve stability and increase functional outcomes&lt;strong&gt;.&lt;/strong&gt;&lt;/p&gt;

Measuring the migration of the components and polyethylene wear after total hip arthroplasty

This paper describes the methodology, validation and reliability of a new computer-assisted method which uses models of the patient's bones and the components to measure their migration and polyethylene wear from radiographs after total hip arthroplasty (THA). Models of the patient's acetabular and femoral component obtained from the manufacturer and models of the patient's pelvis and femur built from a single computed tomography (CT) scan, are used by a computer program to measure the migration of the components and the penetration of the femoral head from anteroposterior and lateral radiographs taken at follow-up visits. The program simulates the radiographic setup and matches the position and orientation of the models to outlines of the pelvis, the acetabular and femoral component, and femur on radiographs. Changes in position and orientation reflect the migration of the components and the penetration of the femoral head. Validation was performed using radiographs of phantoms simulating known migration and penetration, and the clinical feasibility of measuring migration was assessed in two patients. Migration of the acetabular and femoral components can be measured with limits of agreement (LOA) of 0.37 mm and 0.33 mm, respectively. Penetration of the femoral head can be measured with LOA of 0.161 mm. The migration of components and polyethylene wear can be measured without needing specialised radiographs. Accurate measurement may allow earlier prediction of failure after THA. Cite this article: Bone Joint J 2017;99-B:1290-7.