Hemispherical Acetabular Component Research Articles

Can a reconstruction algorithm in major acetabular bone loss be successful in revision hip arthroplasty?

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. 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. A total of 105 procedures were carried out in 100 patients (five bilateral) with a mean age of 73 years (42 to 94). In the IIIA defects treated, 72.0% (36 of 50) required a porous metal augment; the remaining 14 patients were treated with a hemispherical acetabular component alone. In the IIIB defects, 63.6% (35 of 55) underwent reconstruction as planned with 20 patients who actually required a hemispherical acetabular component alone. At mean follow-up of 7.6 years, survival was 94.3% (95% confidence interval 97.4 to 88.1) for all-cause revision and the overall dislocation rate was 3.8% (4 of 105). There was no difference observed in survival between type IIIA and type IIIB defects and whether a hemispherical implant alone was used for the reconstruction or not. The mean gain in OHS was 16 points. Custom-made implants were only used in six cases, in patients with either a mega-defect in which the anteroposterior diameter > 80 mm, complex pelvic discontinuity, and massive bone loss in a small pelvis. Our findings suggest that a reconstruction algorithm can provide a successful approach to reconstruction in major acetabular bone loss. The use of custom implants has been defined in this series and accounts for < 5% of cases.

Определение конгруэнтности стандартного полусферического вертлужного компонента и посттравматически деформированной вертлужной впадины при первичном эндопротезировании тазобедренного сустава (экспериментальное исследование)

Introduction An original ASPID classification was developed for primary total hip arthroplasty in the presence of post-traumatic acetabular deformity at the Vreden National Medical Research Centre for Traumatology and Orthopaedics. We aimed to explore how the extent of displacement and localization of acetabular deformity as classified by the original ASPID grading system can affect the coverage area of the acetabular component. The purpose of the study was to determine the congruence of the standard hemispherical acetabular component and the post-traumatic acetabular deformity in the experiment. Material and methods Computer 3D models of 92 post-traumatic acetabulums were formed, followed by simulated implantation of a standard hemisphere of the appropriate size in compliance with permissible values of the spatial orientation of the acetabular cup in total hip replacement. The congruence of the deformed acetabulum and the standard hemisphere of the corresponding size was determined with simulated implantation. Formula for the acetabular deformity was determined for each case using the original classification. With formula identified for each acetabular deformity and the magnitude of congruence, the data were compared to determine the relationship between congruence, bone displacement and the extent of bone displacement. Results The mean congruence value in the group was 59.5 ± 16.83 %. The sum of the scores A+S+P+I+D was compared with the percentage of congruence. The statistical analysis showed that the congruence of the hemispherical acetabular component and the post-traumatic acetabulum was less than 70% with a sum of parameters greater than four. The continuation of the study will allow for a more global analysis and identification of more patterns to improve surgical approaches to primary total hip arthroplasty in specific cases. Conclusion Screws can be recommended for reliable primary mechanical fixation of the pelvic component in target patients, and cavitary bone defects can be repaired with autobone chips to allow greater congruence at the bone-implant interface.

Robotic-Assisted Total Hip Arthroplasty in Patients Who Have Developmental Hip Dysplasia

Introduction: Total hip arthroplasty (THA) in the setting of developmental dysplasia of the hip (DDH) presents more inherent complexities than routine primary THA for osteoarthritis. These include acetabular bone deficiency, limb length discrepancy (LLD), and abnormal femoral anteversion. Three-dimensional planning and robot-assisted (RA) bone preparation may simplify these complex procedures and make them more reproducible. The purpose of this study was to evaluate radiographic and clinical outcomes in a cohort of patients who had DDH and underwent an RA THA. Materials and Methods: We retrospectively analyzed 26 DDH patients who underwent RA THA by a single surgeon between 2013 and 2019. Their mean age was 54 years (range, 29 to 72 years) and mean follow up was approximately two years. Medical records were reviewed for demographics, clinical scores, Crowe classifications, and complications. There were thirteen Crowe I and seven Crowe II DDH hips, who were routinely managed with primary cementless implants. Two patients who had Crowe III and four patients who had Crowe IV DDH were also identified. All hips were reconstructed with cementless hemispherical acetabular components with or without the use of screws, but no acetabular augments or bulk allografts. Implants allowing control of femoral anteversion were selected in 23.1% of cases, including all six cases with Crowe III or IV dysplasia, and the need for these implants was uniformly identified using preoperative information about femoral version provided by the three-dimensional planning software. No patient was managed with a shortening femoral osteotomy. Postoperative radiographs were examined for LLD, center of rotation (COR), cup position (inclination and anteversion), and component osseous-integration. Results: Mean radiographic LLD was 1.7mm (range, -9 to +14) in patients who had Crowe I DDH, and there was no clinical LLDs greater than 5mm observed. Although patients who had Crowe II and greater DDH had a mean radiographic LLD of -11.6mm (range, -26 to +2.2), again no clinical LLD greater than 5mm was observed other than one patient who had bilateral Crowe II DDH in whom 10mm of clinical lengthening was accepted at the index arthroplasty with the plan to match lengths when her contralateral THA was performed. There were no cases of dislocation or acetabular fixation failure. One patient who had a femoral deformity and an intra-osseous blade plate from a prior femoral osteotomy suffered a failure of femoral osseous-integration, resulting in revision. A 32-point increase in mean modified Harris Hip Score (mHHS) was found (p=0.002), from 48 points preoperatively to 80 points postoperatively. Discussion: RA THA provides an excellent option for the arthroplasty surgeon to both preoperatively localize and characterize the acetabular deficiency, while providing a targeted, optimal, and secure placement of the components intraoperatively. Our results suggest favorable outcomes when compared to previous research on manual THA in DDH. Further studies, including comparative analyses, could discern possible advantages over traditional THA without robotic assistance in DDH. Conclusion: Total hip arthroplasty (THA) in the setting of developmental dysplasia presents more inherent complexities than routine primary THA. Robotic-assisted THA may simplify these complex procedures.

Intraoperative Radiographic Detection of Intrapelvic Acetabular Screw Penetration: Lessons Learned From Our Trauma Colleagues.

BackgroundIntraoperative vascular injury during total hip arthroplasty represents a catastrophic complication. Acetabular screw placement represents one possible mode of injury. The purpose of this study was to evaluate the utility of various fluoroscopic views in the detection of intrapelvic screw penetration.MethodsA radiopaque pelvis Sawbones model was instrumented with a hemispherical acetabular component. Four intrapelvic quadrants were defined. Screws were placed, 3 in each quadrant, and imaged sequentially at 3 depths: 0 mm, 5 mm, and 10 mm penetrated. Eight fluoroscopic images were used: anteroposterior, inlet, outlet, iliac oblique, obturator oblique, “down the wing,” obturator outlet, and a “quad” view. Three blinded, independent surgeons evaluated the images for intrapelvic screw penetration. Images were analyzed in isolation and as a “triple-shot series” consisting of the “quad,” obturator outlet, and iliac oblique views. Sensitivity and specificity values were then calculated.ResultsIn isolation, the “quad” view had the highest sensitivity for screw penetration (62%). The triple-shot series was found to be 100% sensitive in all 4 quadrants for detecting 10 mm of screw penetration. The specificity of the series was found to be 100% in all quadrants except for the posterior superior quadrant where it was 67%. Interobserver agreement approached perfection (Kappa ≥0.947) between all surgeons (P < .001) when using the 3-view series.ConclusionsThis study is the first to assess the use of fluoroscopy in the detection of intrapelvic penetration of transacetabular screws. We found that a 3-radiograph series provided a sensitive and specific metric for the detection of intrapelvic screw penetration.

Acetabular defect classification and management : Revision arthroplasty of the acetabular cup based on 3-point fixation.

BackgroundThe purpose of this study was to provide a practicable and contemporary classification system that is reliable and pragmatic with respect to perioperative evaluation, planning, scientific comparison and analysis.Material and methodsThis was a retrospective study of 160 patients who underwent acetabular revision surgery after THR due to loosening of the acetabular cup. The assessment of the acetabular defect was based on intraoperative description of the bony configuration of the acetabulum as well as on standardized preoperative planning images (pelvic overview and axial view of the hip joint). Preoperative computed tomography (CT) was carried out in individual cases.ResultsAcetabular bone defects were classified into 4 types based on whether or not a 3-point fixation of the acetabular cup within the boundaries of the acetabular cavity was possible. Minor segmental defects or cup loosening without bone loss can be treated with standard hemispherical acetabular components. Bone loss can be filled with bone grafts and/or treated by the appropriate acetabular component in order to ensure stable anchorage. When conventional revision cups are no longer suitable a custom made partial pelvic replacement can be used.ConclusionThe proposed classification mainly relies on intraoperative findings which were confirmed by preoperative imaging in 154 cases out of 160 (96.25%); however, meticulous preoperative planning based on X‑ray radiographs must be carried out. In addition, a CT scan must be performed whenever type III or type IV defects are anticipated. Compared to the existing classification systems, we can state that our classification system is practicable and pragmatic and simplifies the assessment of bone defects.

Assessment of Acetabulum Deformity During Preoperative Planning for Hip Arthroplasty

Purpose of the study — to improve the two-dimensional planning of total hip joint arthroplasty to ensure precise positioning of the acetabular component in the deformed acetabulum. Materials and methods. Features of roentgenological anatomy of acetabulum and its coverage were studied on 1058 hip joint x-rays in the AP view in accordance with the procedure developed by the authors to define acetabular square — the site of standard positioning of a spherical femoral head in the acetabulum or of a hemispherical acetabular component. The method consisted of identifying the apex of “teardrop” figure; the most lateral points of the pelvic terminal line and roof of the acetabulum; superior part of the acetabular cavity; medial and inferior points of acetabular coverage, and building the sides of acetabular square — medial, inferior, lateral and superior boundary lines. Connection of “teardrop” apex and lateral point of the pelvic terminal line formed the medial side of acetabular square, and a perpendicular to that line drawn through the “teardrop” apex to its inferior side. The lateral side was drawn either through the intersection of the ascending diagonal line — bisector from the top of the “teardrop” figure with the contour of the acetabulum roof, or was a part of the projection of the most lateral point of the acetabular roof on the inferior side of the square. The superior side was a perpendicular connecting the intersection of the ascending diagonal and lateral bounding lines with the medial side of the acetabular square. The area of the deformed acetabular cavity located outside of the acetabular square was assessed as the acetabular defect. Results. Method of defining the acetabular square allowed to identify types of ratios between acetabular cavity and acetabular coverage in transverse (9 types) and longitudinal (7 types) direction. Combination of transverse ratio of acetabular cavity and coverage with longitudinal type allowed to define the options of acetabular deformities in two-dimensional view. The authors identified 25 types of acetabular deformities. Bone defects of acetabular walls were of the major importance among all anatomical features. Cranial defect of acetabulum was observed in 450 cases, medial wall defect — in 38 cases, defect including cranial and medial areas — in 7 cases. Conclusion. The method suggested by the authors to determine acetabular square and acetabular deformity variations allows to screen the anatomical features of the acetabulum during two-dimensional preoperative planning and to make an informed decision on the need to use other planning techniques. The type of acetabular deformity identified during preoperative planning allows to elaborate the indications for replacement of acetabular bone defects and/or resection of acetabular osteophytes.

Classifications in Brief: The Hartofilakidis Classification of Developmental Dysplasia of the Hip

Classifications in Brief: The Hartofilakidis Classification of Developmental Dysplasia of the Hip

Pelvic Discontinuity Associated With Total Hip Arthroplasty: Evaluation and Management.

Pelvic discontinuity is a challenging complication encountered during revision total hip arthroplasty. Pelvic discontinuity is defined as a separation of the ilium superiorly from the ischiopubic segment inferiorly and is typically a chronic condition in failed total hip arthroplasties in the setting of bone loss. After a history and a physical examination have been completed and infection has been ruled out, appropriate imaging must be obtained, including plain hip radiographs, oblique Judet radiographs, and often a CT scan. The main management options are a hemispheric acetabular component with posterior column plating, a cup-cage construct, pelvic distraction, and a custom triflange construct. The techniques have unique pros and cons, but the goals are to obtain stable and durable acetabular component fixation and a healed or unitized pelvis while minimizing complications.

Management of massive acetabular bone defects in revision arthroplasty of the hip using a reconstruction cage and porous metal augment.

It may not be possible to undertake revision total hip arthroplasty (THA) in the presence of massive loss of acetabular bone stock using standard cementless hemispherical acetabular components and metal augments, as satisfactory stability cannot always be achieved. We aimed to study the outcome using a reconstruction cage and a porous metal augment in these patients. A total of 22 acetabular revisions in 19 patients were performed using a combination of a reconstruction cage and porous metal augments. The augments were used in place of structural allografts. The mean age of the patients at the time of surgery was 70 years (27 to 85) and the mean follow-up was 39 months (27 to 58). The mean number of previous THAs was 1.9 (1 to 3). All patients had segmental defects involving more than 50% of the acetabulum and seven hips had an associated pelvic discontinuity. Three failures were observed in two hips, both of which had undergone a previous resection of a tumour affecting the acetabulum. Other complications included a late arterial injury, a sciatic nerve palsy, a dislocation treated with a femoral revision, a deep infection treated with irrigation and debridement and a fracture of the greater trochanter treated conservatively. The mean Oxford Hip Score significantly increased from 13.9 (2 to 23) to 28.7 (13 to 38) (p < 0.00001). The mean vertical distance between the centre of rotation of the hip and its normal location decreased from 30 mm to 10 mm. Acceptable early survivorship can be achieved using this novel technique, but it may be unsuitable for use in patients who have previously undergone the resection of a tumour involving the acetabulum. Cite this article: Bone Joint J 2017;99-B:607-13.

Iliopsoas Impingement After Primary Total Hip Arthroplasty: Operative and Nonoperative Treatment Outcomes.

A potential cause of persistent groin pain after total hip arthroplasty is impingement of the iliopsoas tendon. Treatment options include conservative management, tenotomy, and acetabular revision, but the literature, to our knowledge, has been limited to small case series on each technique. We present a series of patients with iliopsoas impingement after total hip arthroplasty and evaluate efficacy and risk factors for success or failure of each treatment strategy. Forty-nine patients treated at one institution for a diagnosis of iliopsoas impingement after primary total hip arthroplasty with hemispherical acetabular component and polyethylene bearing were retrospectively reviewed. Twenty-one patients underwent acetabular revision, 8 patients underwent tenotomy, and 20 patients had nonoperative management. The mean follow-up was 4 years. Anterior acetabular component prominence was measured on true lateral hip radiographs. At the most recent follow-up, 10 patients (50%) in the nonoperative group had groin pain resolution compared with 22 patients (76%) in the operative group (p = 0.06). In patients with <8 mm of component prominence, tenotomy provided resolution of groin pain in 5 (100%) of 5 patients and a mean Harris hip score of 89 points. In patients with ≥8 mm of prominence, acetabular revision led to groin pain resolution in 12 (92%) of 13 patients compared with 1 (33%) of 3 patients treated with tenotomy (p = 0.07). Nonoperative management of iliopsoas impingement led to groin pain resolution in 50% of patients. In patients with minimal acetabular component prominence, iliopsoas release provided a high rate of success. Acetabular revision was more predictable for groin pain resolution in patients with ≥8 mm of anterior component prominence. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Is the Direct Superior, Iliotibial Band-Sparing Approach Associated With Decreased Pain After Total Hip Arthroplasty?

BackgroundRecently, the direct superior approach (DSA) has been introduced in total hip arthroplasty (THA) with the goal of limiting soft tissue dissection. This study's purpose was to use a visual pain diagram questionnaire to determine the location and severity of pain in patients undergoing THA via a DSA vs miniposterior approach (MPA). MethodsThis was a prospective, Institutional Review Board (IRB)-approved investigation from 3 centers. Patients aged 18-70 years with a diagnosis of osteoarthritis were included. Two centers used the MPA, while 1 center the DSA. The DSA uses a 9- to 12-cm incision with its distal extent at the posterosuperior greater trochanter. Dissection into the iliotibial band is avoided, and the capsule at the inferior femoral neck is preserved. All THAs in both cohorts received a cementless, titanium, proximally coated femoral stem and a hemispherical acetabular component. ResultsA total of 42 DSA and 196 MPA THA patients were included. Overall, 43% of patients reported pain in at least 1 of the 8 anatomic areas assessed. There was no difference in the incidence of moderate to severe pain in any anatomic area of interest between the MPA and DSA cohorts (P = .1-.9). Specifically, the incidence of moderate to severe trochanter (17% MPA vs 17% DSA, P = .9), anterior thigh (15% MPA vs 17% DSA, P = .9), and lateral thigh pain (12% MPA vs 12% DSA, P = .9) was nearly identical in both cohorts. ConclusionThis study was unable to demonstrate a difference in the incidence of residual pain after use of a DSA or an MPA approach after THA.

Accuracy of the modified Hardinge approach inacetabular positioning.

The surgical approach chosen for total hip arthroplasty (THA) may affect the positioning of the acetabular component. The purpose of this study was to examine the accuracy in orienting the acetabular component using the modified Hardinge approach. We used our institutional arthroplasty database to identify patients with primary, press-fit, hemispherical acetabular components of a metal-on-polyethylene THA performed between 2003 and 2011. Patients with radiographs obtained 1-3 years after the index procedure were included for measurement of anteversion and inclination angles. Acceptable values of anteversion and abduction angles were defined as 15° ± 10° and 40° ± 10°, respectively. We identified 1241 patients from the database, and the modified Hardinge approach was used in 1010 of the patients included in our analysis. The acetabular component was anteverted in the acceptable zone in 54.1% of patients. The abduction angle was within the defined range in 79.2% of patients. Combined anteversion and abduction angles within the defined zone were present in 43.6% of patients. Consistent with studies examining accuracy from other approaches, our study reveals that the modified Hardinge approach was only moderately accurate in positioning the acetabular component in the acceptable zone.

Role of Cages in Revision Arthroplasty of the Acetabulum.

➤ The outcome of acetabular revision is heavily influenced by the degree of associated bone loss.➤ Uncemented hemispherical acetabular components can be used in the majority of acetabular revisions, although occasionally the degree of bone loss precludes the stability of the hemispherical component at the correct anatomic level or there is minimal bleeding host bone left for biologic fixation.➤ Massive acetabular bone loss resulting in the need for bone grafts or highly porous augments involving more than half of the acetabulum is one of the main indications for the use of cages.➤ The cup-cage reconstruction is based on bone-grafting the deficient acetabulum and securing a hemispherical, highly porous metal component with multiple screws to bridge the discontinuity and off-loading the hemispherical component with a titanium cage spanning from ischium to ilium.➤ In addition to managing pelvic discontinuities, the cup-cage construct can also be used in hips without discontinuity as the hemispherical, highly porous metal component is used to restore bone stock.➤ In situations in which there is not enough bleeding host bone to secure a hemispherical component, a highly porous metal augment can be used to address the osseous deficiency. The augment is also protected with a cage to assist bone ingrowth.

The role of cages in the management of severe acetabular bone defects at revision arthroplasty.

An uncemented hemispherical acetabular component is the mainstay of acetabular revision and gives excellent long-term results. Occasionally, the degree of acetabular bone loss means that a hemispherical component will be unstable when sited in the correct anatomical location or there is minimal bleeding host bone left for biological fixation. On these occasions an alternative method of reconstruction has to be used. A major column structural allograft has been shown to restore the deficient bone stock to some degree, but it needs to be off-loaded with a reconstruction cage to prevent collapse of the graft. The use of porous metal augments is a promising method of overcoming some of the problems associated with structural allograft. If the defect is large, the augment needs to be protected by a cage to allow ingrowth to occur. Cup-cage reconstruction is an effective method of treating chronic pelvic discontinuity and large contained or uncontained bone defects. This paper presents the indications, surgical techniques and outcomes of various methods which use acetabular reconstruction cages for revision total hip arthroplasty.

Pelvic Tilt in Patients Undergoing Total Hip Arthroplasty: When Does it Matter?

Pelvic tilt (PT) affects the functional anteversion and inclination of acetabular components in total hip arthroplasty (THA). One-hundred and thirty-eight consecutive patients who underwent unilateral primary THA were reviewed. Most cases had some degree of pre-operative PT, with 17% having greater than 10° of PT on standing pre-operative radiographs. There was no significant change in PT following THA. A computer model of a hemispheric acetabular component implanted in a range of anatomic positions in a pelvis with varying PT was created to determine the effects of PT on functional anteversion and inclination. Based on the study results, tilt-adjustment of the acetabular component position based on standing pre-operative imaging will likely improve functional component position in most patients undergoing THA.

A Metal/Ultrahigh-Molecular-Weight Polyethylene Cementless Surface Replacement

Cementless metal/ultrahigh-molecular-weight polyethylene (UHMWPE) hip replacements that use less than hemispherical acetabular components and a short tapered femoral stem were developed in 1983 by the use of cobalt-chromium alloy and conventional GUR 415 polyethylene sterilized by ethylene oxide. These devices improved the fixation failures seen with cemented, fully hemispherical acetabular cups but encountered wear and osteolysis problems in the medium to long term. More wear-resistant titanium nitride ceramic bearings, developed in 1989, coupled with porous coated, cementless fixation, demonstrated midterm survivorship of 91.8% at 6 years but also developed long-term wear and osteolysis problems associated with conventional polyethylene. Recent advances in wear-resistance with the use of highly crosslinked polyethylene has prompted a renewed examination of the cementless resurfacing concept, allowing bearing exchange and retention of well-fixed resurfacing implants with these improved bearings as well as primary resurfacing hip replacement, using conventional surgical techniques. An anticipated 60%-90% reduction in wear and osteolysis, on the basis of long-term clinical and mechanical simulator data, makes this cementless application a significant alternative to cemented metal-metal resurfacing.

Porous Metal Augments: Big Hopes for Big Holes

The majority of acetabular defects can be reconstructed with a hemispherical acetabular component alone. However, severe bone loss encountered at the time of revision acetabular surgery can result in compromised initial fixation leading to component micromotion, failure of bone ingrowth, and mechanical failure. Porous acetabular augments offer a potential solution to enhance initial component fixation while maximizing the area for biologic ingrowth. Premanufactured metal augments can be placed independent of the acetabular component. This feature provides surgeons the flexibility to place the hemispherical acetabular component in the optimal orientation at the anatomic hip center. The augment is initially secured to the hemipelvis with multiple screws before it is then secured to the hemispherical acetabular component with the use of polymethylmethacrylate bone cement. The modularity of the augments effectively allows a custom implant to be designed intraoperatively. Porous acetabular augments offer the potential advantages of a nonresorbable material that can be inserted without extensive soft tissue stripping. Additionally, these metal augments do not carry the risk of disease transmission associated with bulk structural allograft and are manufactured in a variety of shapes and sizes. The early clinical and radiographic results of porous acetabular augments are promising, yet there remains a paucity of long-term data.

The Jumbo Cup: The 95% Solution

Extra large uncemented hemispherical acetabular components, also known as jumbo cups, are commonly used for acetabular revision surgery. This article reviews the advantages and disadvantages, definition, indications, technique, and published results utilizing jumbo cups.

Cementless Hemispheric Acetabular Component for Acetabular Revision Arthroplasty: A 5- to 19-Year Follow-Up Study

This study evaluated the 5- to 19-year clinical and radiographic results of cementless acetabular revision. Between 1986 and 1998, 130 hips (125 patients) underwent cementless acetabular revisions. Ten patients were lost to follow-up; 6 patients died. One hundred nine patients (114 hips) were reviewed at a mean follow-up of 8.8 years. The mean Harris hip score improved from 62.1 to 90.7 at final follow-up. Two hips underwent repeat revision. Twenty-two hips developed cavitary osteolysis. Kaplan-Meier survivorship at 121 months was 98.2% with repeat revision for any reason as the end point and 89.5% with repeat revision or radiographic loosening as the end point. Cementless acetabular revision provides favorable clinical and radiographic results, and the initial disease and age may adversely affect the outcomes.

The Potential for Bone Loss in Acetabular Structures Following THA

Attempts to preserve periacetabular bone stock following total hip replacement have largely ignored the potential for stress shielding in the acetabulum. We sought to quantify the change in stress distribution in acetabular bone with components of varying material stiffness by developing a high-resolution 3-D finite element model from CT scans of a young female donor. Periprosthetic bone stresses and strains on the left pelvis were compared with hemispherical cups of various material properties and with a horseshoe shaped polymeric design described in the recent literature. We observed unphysiologic periacetabular bone stress and strain fields for all designs tested. For hemispherical components, reduction of the acetabular shell material modulus caused modest changes in bone stress compared to the changes in implant geometry. The horseshoe shaped cup more effectively loaded the acetabular structures than the hemispherical design. Our results suggest stress and strain fields in pelvic structures after introduction of hemispherical acetabular components predict inevitable bone adaptation that can not be resolved by changes in implant material properties alone. Radical changes in implant design may be necessary for long-term maintenance of supporting structures in the reconstructed acetabulum.