Loss Of Acetabular Bone Stock Research Articles

A Comparative Study Between the Stryker EZout Powered Acetabular Revision System and the Zimmer Explant Acetabular Cup Removal Systems

The conservation of bone stock and the decrease of intraoperative acetabular fracture risk associated with revision surgery is a primary goal to improve the outcome of the procedure. The objective of this study was to evaluate and compare the performance of the Explant Acetabular Cup Removal System and the EZout Powered Acetabular Revision System in an in vitro model. Acetabular components were implanted into instrumented composite hemipelvises and divided into 2 groups, EZout System and Explant System. One experienced orthopedic surgeon and 1 orthopedic resident physician performed the removal procedures. The strains at various points in the periacetabular bone, the temperature at the implant-bone interface, the total time to removal, the torque applied to the implant and the amount of acetabular foam on each cup after extraction, as a surrogate for cavitary acetabular bone stock loss, were calculated for each test. Statistical analysis was conducted using 2-way multivariate analysis of variance followed by Tukey honestly significant difference multiple comparisons. The EZout System required an overall lower force and torque (P<0.0001, both) during removal, producing lower strains in the surrounding composite bone. The procedure was faster (P<0.0001) and less energy demanding with the EZout compared with the Explant. The amount of foam on the cup was on average less for the EZout than for the Explant (P<0.05). We found that the EZout System is effective in achieving safe removal of a well-fixed acetabular component in an in vitro model of cementless fixation. This system should be considered as a reasonable alternative to manual removal techniques.

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.

Un essai pilote comparant le comportement à l’arrachement des cupules metal-back vissantes et cimentées en polyéthylène : étude cadavérique cas témoin

BackgroundThe removal of well-fixed acetabular components following total hip arthroplasty (THA) is a difficult operation and could be accompanied by the loss of acetabular bone stock. The optimal method for fixation is still under debate. The aim of this pilot study was to compare the tear-out resistance and failure behavior between osseo-integrated and non-integrated screw cups. Furthermore, we examined examined whether there are differences in the properties mentioned between screw sockets and cemented polyethylene cups. HypothesisTear-out resistance and related mechanical work required for the tear-out of osseo-integrated screw sockets are higher than in non-integrated screw sockets. Patients and methodsTen human coxal bones from six cadavers with osseo-integrated screw sockets (n=4), non-integrated (implanted postmortem, n=3) screw sockets and cemented polyethylene cups (n=3) were used for tear-out testing. The parameters axial failure load and mechanical work for tear-out were introduced as measures for determining the stability of acetabular components following THA. ResultsThe osseo-integrated screw sockets yielded slightly higher tear-out resistance (1.61 ± 0.26kN) and related mechanical work compared to the non-integrated screw sockets (1.23 ± 0.39kN, P=0.4). The cemented polyethylene cups yielded the lowest tear-out resistance with a failure load of 1.18±0.24kN. Compared to the screw cups implanted while alive, they also differ on a non-significant level (P=0.1). Osseous failure patterns differed especially for the screw sockets compared to the cemented polyethylene cups. DiscussionOsseo-integration did not greatly influence the tear-out stability in cementless screw sockets following axial loading. Furthermore, the strength of the bone–implant interface of cementless screw sockets appears to be similar to cemented polyethylene cups. However, given the high failure load, high mechanical load and because of the related bone failure patterns, removal should not be performed by means of tear-out but rather by osteotomes or other curved cutting devices to preserve the acetabular bone stock. Level of evidenceLevel III, case-control-study.

Impact of individual anatomy on the benefit of cup medialisation in total hip arthroplasty.

In total hip arthroplasty, cup medialisation with compensatory increase of femoral offset has been proposed to increase the moment arms of abductor muscles. However, this technique is associated with a loss of acetabular bone stock. Previous data indicates that the potential benefit is not constant among patients and is likely related to patient anatomy. Therefore, to be able to select patients who would benefit most from this technique, we measured several anatomical parameters of the pelvis and femur in 15 patients; and evaluated correlations between them and the changes of moment arms associated with cup medialisation. The anatomical measurements were performed on 3-D reconstructions of preoperative CT scans. The moment arms of the gluteus medius and gluteus minimus were calculated for an abduction and flexion movement using patient-specific finite element models. 6 anatomical parameters were correlated with muscle moment arm variations after cup medialisation. This effect was not systematic for either muscles or movements. Among all parameters, femoral anteversion was the most important parameter in explaining the effect of cup medialisation. Patients with small femoral anteversion or low-riding greater trochanter benefit more from cup medialisation in terms of moment arm increase in abduction motion.

A pilot trial comparing the tear-out behavior in screw-sockets and cemented polyethylene acetabular components – a cadaveric study

BackgroundThe removal of well-fixed acetabular components following THA (total hip arthroplasty) is a difficult operation and could be accompanied by the loss of acetabular bone stock. The optimal method for fixation is still under debate. The aim of this pilot study was to compare the tear-out resistance and failure behavior between osseo-integrated and non-integrated screw cups. Furthermore, we examined whether there are differences in the properties mentioned between screw sockets and cemented polyethylene cups. HypothesisTear-out resistance and related mechanical work required for the tear-out of osseo-integrated screw sockets are higher than in non-integrated screw sockets. Patients and methodsTen human coxal bones from six cadavers with osseo-integrated screw sockets (n=4), non-integrated (implanted post-mortem, n=3) screw sockets and cemented polyethylene cups (n=3) were used for tear-out testing. The parameters axial failure load and mechanical work for tear-out were introduced as measures for determining the stability of acetabular components following THA. ResultsThe osseo-integrated screw sockets yielded slightly higher tear-out resistance (1.61±0.26kN) and related mechanical work compared to the non-integrated screw sockets (1.23±0.39kN, P=0.4). The cemented polyethylene cups yielded the lowest tear-out resistance with a failure load of 1.18±0.24kN. Compared to the screw cups implanted while alive, they also differ on a non-significant level (P=0.1). Osseous failure patterns differed especially for the screw sockets compared to the cemented polyethylene cups. DiscussionOsseo-integration did not greatly influence the tear-out stability in cementless screw sockets following axial loading. Furthermore, the strength of the bone-implant-interface of cementless screw sockets appears to be similar to cemented polyethylene cups. However, given the high failure load, high mechanical load and because of the related bone failure patterns, removal should not be performed by means of tear-out but rather by osteotomes or other curved cutting devices to preserve the acetabular bone stock. Level of evidenceLevel III, case-control-study.

Impaction grafting for acetabular reconstruction in primary and revision hip arthroplasty

Background Acetabular bone stock loss is a major problem in both primary and revision total hip arthroplasty (THA). The loosening of primary cemented and cementless components of THAs is also accompanied by a loss of bone stock. There are several options for reconstruction of the acetabular defects. In 1979, a biologic method was introduced with tightly impacted cancellous allografts in combination with a cemented polyethylene cup for acetabular reconstruction, to restore acetabular bone stock, to restore normal hip biomechanics, and to allow for further revision if needed. Aim of the work In this study, the results of using morcellized impacted bone graft to reconstruct the deficient acetabulum in 54 hips (49 patients) using either cemented or cementless cups are discussed, with a mean follow-up of 36 (6–96) months. Patients and methods Between May 2002 and April 2010, 54 hips (in 49 patients) with deficient bone stock on the acetabular side had undergone total replacement with acetabular reconstruction using morcellized bone impaction grafting; out of the 54 hips, 34 (63%) were primary THA (17 after fracture of the acetabulum, 12 for protrusio acetabuli, three for rheumatoid arthritis, one for dysplastic hip, and one after tuberculosis arthritis) and 20 hips (37%) were revision THA. There were 21 (43%) women (bilateral in three of them) and 28 (57%) men (bilateral in two of them). Average age was 53 years (range 26–98 years). Out of the 54 hips, 14 (26%) were cementless and 40 (74%) were cemented. Mesh was used in 27 (50%) hips to convert a noncontained defect into a contained defect. Octopus ring was used in one hip, and Muller ring was used in another hip to overcome pelvic discontinuity. Results Fifty-four hips in 49 patients were followed up clinically and radiologically, with a mean follow-up of 36 months. In 46 hips (95.8%), the graft showed radiological signs of union to the host bone and no cup loosening. Cup was loose and revised in two patients (4.2%). One patient had octopus ring and morcellized graft in the first operation, and it was revised using a mesh and morcellized graft 8 years later. The other patient had morcellized graft and Muller ring; this failed after 4 years with cup loosening. It was revised using mesh and morcellized graft. Conclusion Acetabular reconstruction is a demanding procedure and needs preoperative planning and armamentarium. Successful results were obtained using the impaction technique for reconstruction. The aim of bone graft is to restore the normal hip mechanics. The union rate of the impacted graft is relatively satisfactory compared with other grafting methods. Augmentation of the grafting technique by mesh or rings added more stability to the cup component. The use of impaction graft in revisions for infected hip did not increase the risk of reinfection.

Two-stage treatment of acetabular bone defect in tuberculosis of the hip by intended ankylosis followed by total hip arthroplasty: a case report

In case of severe post-tuberculosis osteoarthritis of the hip, arthrodesis, excision arthroplasty, or total hip arthroplasty may be considered. The latter can be challenging, because destruction of the joint, and most importantly the acetabulum, is frequently seen. To fill up acetabular bone stock loss during total hip arthroplasty, there is the possibility to use bone auto-grafts and allografts. Complications are graft rejection, mechanical failure of implants and gradual migration of the cup into the graft. Other options for creating a stable acetabular component in total hip replacement are screw fixation of the acetabular component or using a stemmed acetabular component. An alternative is the use of an anti-protrusion cage, for which the risk of loosening however is known. In young patients especially, such solution are not always appealing. Therefore, we created an intended ankylosis of the hip joint to fill up the acetabular bone loss with the patients own femoral head. To our knowledge this treatment strategy has not been described before.We present a 33-year-old Caucasian woman with an acetabular bone defect caused by tuberculous arthritis of the left hip joint. Instead of performing a resection arthroplasty followed by total hip arthroplasty in a second stage, we decided to intentionally ankylose the hip joint in order to fill up the acetabular defect with the patient's own femoral head. Two years after the start of a one year course of tuberculostatic chemotherapy, we took down the ankylosed hip and placed an uncemented total hip prosthesis. The technical and functional outcome of this procedure appeared to be very favourable, the acetabular defect was filled up and the bone remodeled completely.In order to resolve the problem of acetabular osseous defects in tuberculous arthritis of the hip, intended spontaneous fusion of the femoral head with the acetabular can be a favorable treatment strategy. Subsequently this situation was used as a solid base for the acetabular component of the total hip prosthesis. It resulted in a optimal acetabular bone stock during acetabular component implantation with a very good technical and clinical outcome at 40-months follow up It is understood that this method may not be applicable to all resembling patients. However, this solution may be considered worthwhile in individual cases.

Two-stage treatment of acetabular bone defect in tuberculosis of the hip by intended ankylosis followed by total hip arthroplasty: a case report.

In case of severe post-tuberculosis osteoarthritis of the hip, arthrodesis, excision arthroplasty, or total hip arthroplasty may be considered. The latter can be challenging, because destruction of the joint, and most importantly the acetabulum, is frequently seen. To fill up acetabular bone stock loss during total hip arthroplasty, there is the possibility to use bone auto-grafts and allografts. Complications are graft rejection, mechanical failure of implants and gradual migration of the cup into the graft. Other options for creating a stable acetabular component in total hip replacement are screw fixation of the acetabular component or using a stemmed acetabular component. An alternative is the use of an anti-protrusion cage, for which the risk of loosening however is known. In young patients especially, such solution are not always appealing. Therefore, we created an intended ankylosis of the hip joint to fill up the acetabular bone loss with the patients own femoral head. To our knowledge this treatment strategy has not been described before. We present a 33-year-old Caucasian woman with an acetabular bone defect caused by tuberculous arthritis of the left hip joint. Instead of performing a resection arthroplasty followed by total hip arthroplasty in a second stage, we decided to intentionally ankylose the hip joint in order to fill up the acetabular defect with the patient's own femoral head. Two years after the start of a one year course of tuberculostatic chemotherapy, we took down the ankylosed hip and placed an uncemented total hip prosthesis. The technical and functional outcome of this procedure appeared to be very favourable, the acetabular defect was filled up and the bone remodeled completely. In order to resolve the problem of acetabular osseous defects in tuberculous arthritis of the hip, intended spontaneous fusion of the femoral head with the acetabular can be a favorable treatment strategy. Subsequently this situation was used as a solid base for the acetabular component of the total hip prosthesis. It resulted in a optimal acetabular bone stock during acetabular component implantation with a very good technical and clinical outcome at 40-months follow up It is understood that this method may not be applicable to all resembling patients. However, this solution may be considered worthwhile in individual cases.

Metal-on-Metal Hip Resurfacing: Advantages and Disadvantages

Modern metal-on-metal resurfacing has recently gained popularity as an alternative to standard stemmed total hip arthroplasty. This study analyzed, from a literature review, the purported advantages and disadvantages of resurfacing with a comparison to standard hip arthroplasty. Advantages may include bone conservation on the femoral side with possible lower dislocation rates, more range-of-motion, more normal gait pattern, increased activity levels, increased ease of insertion with proximal femoral deformities or retained hardware, and straightforward revision. Possible disadvantages of resurfacing are increased difficulty to perform the procedure, increased acetabular bone stock loss, femoral neck fractures, and concerns about the effects of metal ions. Many of these issues will need further clarification by well-planned prospective studies and evaluation of longer-term outcomes.

The use of structural periacetabular allografts in acetabular revision surgery: 2.5–5 years follow-up

"Acetabular bone loss" presents a major reconstructive challenge in total hip arthroplasty. Loss of acetabular bone stock is a consequence of removal of bone during the original procedure, subsequent prosthetic failure and osteolysis resulting from wear particles of cement and polyethylene. In case of severe bone loss treatment options are rather limited, as fixation requires either biological (cancellous allograft with cage or structural allograft) or non-biological (trabecular metal, triflange implant, etc.) scaffolds. Fourteen acetabular revisions with a cemented cup, supported by a deep frozen structural periacetabular allograft without using a reinforcement ring or an antiprotrusio cage were performed. Clinical assessment was done using a Harris hip score. Graft resorption was radiographically quantified using a digital measurement program. Kaplan-Meier survivorship was 67.1% at 42 months. After a mean follow-up of 3.6 years, 9 out of 14 patients had good clinical results. Mean resorption of 17.1% in six out of ten patients was observed. No sound evidence for union was found in nine out of ten patients. In the four re-revised patients, no bone stock restoration was found. The bicortical allograft without protective device seems to function as a passive biocompatible dead scaffold, which has a less intrinsic strength at intermediate term follow-up, compared to the by ring or cage protected structural allografts.

Long-Term Results of Anti-Protrusio Cage and Massive Allografts for the Management of Periprosthetic Acetabular Bone Loss

From 1992 to 1995, 71 total hip arthroplasties with extensive acetabular bone loss underwent revision using bulk allografts and Burch-Schneider anti-protrusio cages. Twelve patients died of unrelated causes and 3 were lost to follow-up. Fifty-six hips were available for clinical and radiographic follow-up examination at an average of 11.7 years after surgery. The average final Harris hip score was 75. X-ray signs of incorporation of massive bone graft were observed in 49 hips. Two cases developed deep infection that required resection arthroplasty. Aseptic loosening of the acetabular cage occurred in 5 patients, and 2 of them underwent re-revision. With a total survival rate of 87.5%, anti-protrusio cages and structural allografts compare favorably with other techniques in the long-term reconstructive treatment of extensive loss of acetabular bone stock.

Results of acetabular wiremesh and autograft in protrusio acetabuli

Between 1990 and 2005, 25 acetabular reconstructions in 25 patients were performed using autogenous morcellized bone-graft and acetabular wiremesh due to acetabular bone stock loss. The most frequent preoperative diagnosis in our patients were severe hip arthrosis (50%), and rheumatoid arthritis (15%).The mean follow up was 8.6 years (range 2-15 years). The most frequent long-term complication was the appearence of radiolucent lines.A cemented acetabular cup was used in all cases. Preoperative mean Harris Hip Score was 42.3, rising to 90.6 at follow-up after surgery. None of the patients had any loosening of the acetabular component and only one had radiolucent lines >2mm which did not progress. Kohler's line remained intact in all cases.Results of this study suggests bone-grafting and acetabular wiremesh is an effective and simple method to arrest the progresion of acetabular protrusio.

Results of acetabular wiremesh and autograft in protrusio acetabuli

Between 1990 and 2005, 25 acetabular reconstructions in 25 patients were performed using autogenous morcellized bone-graft and acetabular wiremesh due to acetabular bone stock loss. The most frequent preoperative diagnosis in our patients were severe hip arthrosis (50%), and rheumatoid arthritis (15%).The mean follow up was 8.6 years (range 2-15 years). The most frequent long-term complication was the appearence of radiolucent lines.A cemented acetabular cup was used in all cases. Preoperative mean Harris Hip Score was 42.3, rising to 90.6 at follow-up after surgery. None of the patients had any loosening of the acetabular component and only one had radiolucent lines >2mm which did not progress. Kohler's line remained intact in all cases.Results of this study suggests bone-grafting and acetabular wiremesh is an effective and simple method to arrest the progresion of acetabular protrusio.

Removal of acetabular bone in resurfacing arthroplasty of the hip

Sir , We read with interest the article by Loughead et al[1][1] in the January 2006 issue entitled ‘Removal of acetabular bone in resurfacing arthroplasty of the hip: a comparison with hybrid total hip arthroplasty’. Its demonstration that there is a greater loss of acetabular bone stock in

Gültigkeit und Reproduzierbarkeit radiologischer Klassifikationskriterien des knöchernen Substanzdefekts vor Revisionshüftendoprothetik

It was the purpose of this prospective study to analyze validity and reliability of three different radiographic classification systems, which are used to assess bone stock loss prior to revision total hip arthroplasty. Investigation was performed using the classification systems according to 1) Paprosky et al., 2) Hungerford et al., and 3) the German Society of Orthopaedics and Traumatology (DGOT). Twenty-eight consecutive patients with diagnosis of aseptic failure of total hip arthroplasty were enrolled in the study. Interrater agreement was analyzed by evaluating the classifications preoperatively by three investigators with different level of clinical experience using a blinded observer technique. Validity was analyzed by comparison of preoperative radiographic findings (n = 3) and an intraoperative control by visualization and palpation (n = 1). Spearman coefficient of correlation (r(s)) was used to establish levels of agreement among multiple ordinal variables. Interrater reliability testing using paired comparison between the three investigators revealed non-homogeneous coefficients of correlation (r(s): Paprosky femur: 0.45 - 0.67, acetabulum: 0.38 - 0.63; Hungerford: 0.46 - 0.66; DGOT femur: 0.38 - 0.59, acetabulum: 0.42 - 0.76). Paired analysis of correlation between preoperative and intraoperative findings again showed non-homogeneous coefficients of correlation (r(s): Paprosky femur: 0.59 - 0.68, acetabulum: 0.39 - 0.70; Hungerford: 0.39 - 0.74; DGOT femur: 0.44 - 0.60, acetabulum: 0.36 - 0.76). In general, defects were grossly underestimated preoperatively. The level of experience did not influence the validity of measurements. Our results indicate that these classifications do not provide valid and reliable assessment of femoral and acetabular bone stock loss prior to revision total hip arthroplasty.

Polyethylene liner dissociation in Harris-Galante acetabular components: A report of 7 cases

Harris-Galante modular acetabular components (Zimmer, Warsaw, IN) have been used widely for primary and revision total hip arthroplasties. The survivorship of this implant has been well documented in the literature. Failure of the liner locking mechanism and subsequent dissociation of the polyethylene liner from the metal-backed shell is a potential cause of failure, however. We report 7 cases of liner dissociation and propose the mode of failure. The result in all cases was a well-fixed metal acetabular shell with a failed locking mechanism, which usually is managed by revision of the entire component. This procedure may be accompanied by the potential loss of acetabular bone stock, which should be replenished.

Acetabular reconstruction with bone impaction grafting and a cemented cup: 20 years' experience.

Acetabular bone stock loss compromises the outcome in primary and revision total hip arthroplasty. In 1979, a biologic method was introduced with tightly impacted cancellous allografts in combination with a cemented polyethylene cup for acetabular reconstruction. With this technique, it is possible to replace the loss of bone and to repair normal hip mechanics and hip function with a standard implant. Based on the authors' 20 years experience, a review of the long-term data is presented in primary total hip arthroplasty with preexisting acetabular bone stock loss, primary total hip arthroplasty in rheumatoid arthritis, patients who had bone impaction when younger than 50 years, and in acetabular revisions. The survival rate with revision of the cup for aseptic loosening as the end point was 94% at 10 to 17 years, 90% at 10 to 18 years, 91% at 10 to 17 years, and 92% at 10 to 15 years. From biopsy specimens from humans and histologic data in animal experiments the incorporation of these impacted bone chips was proven. The acetabular bone impaction technique using large morselized bone chips (range, 0.7-1 cm) and a cemented cup is a reliable technique with favorable long-term outcome.

Reliability of acetabular bone defect classification systems in revision total hip arthroplasty

Three classifications for assessment of acetabular bone loss were evaluated for their reliability. The 3 systems assessed were the system described by Gross, the system described by Paprosky, and the classification of the American Academy of Orthopaedic Surgeons. In this study, we assessed their reliability based on the preoperative radiographs alone. Intraobserver agreement was measured by evaluating the classifications by the 3 innovators, 3 reconstructive orthopaedic surgeons, and 3 residents. Interobserver agreement was assessed among the reconstructive surgeons and the residents. The unweighted κ statistic was used to establish levels of agreement. The innovators had better intraobserver agreement than the other 2 groups. Their agreement was only in the moderate range, however. For the noninnovators, intraobserver and interobserver agreement generally was poor for all 3 classifications assessed. Our results indicate that these classifications do not provide statistically reliable information for preoperative assessment of acetabular bone stock loss.

Acetabular reconstruction with impacted morcellized cancellous bone autograft and cemented primary total hip arthroplasty: A 10- to 17-year follow-up study

During the period 1979 through 1986, 69 acetabular reconstructions in 63 patients were performed with the use of autologous morcellized bone-grafts because of acetabular bone stock loss. Nine cases (10 hips) were lost to follow-up. Eleven patients (12 hips) died <10 years after surgery; none had a revision. The results for the remaining 43 patients (47 hips) were reviewed at an average interval of 12.3 years (range, 10-17 years). No preoperative Harris hip score was available. The average Harris hip score at follow-up was 88 (range, 60-100). Radiographically, all grafts united. One hip developed a deep infection. Three other hips (6%) were revised because of aseptic loosening of the acetabular component. An additional 3 acetabular components were considered radiographic failures. Excluding the infected case, the overall survival rate of these acetabular reconstructions with a revision as endpoint was 94% at an average follow-up of 12.3 years. Reconstruction of acetabular bone stock loss with autologous morcellized bone-grafts is an attractive technique with a good potential for long-term success.

A study of implant failure in the Wagner resurfacing arthroplasty.

Using clinical, radiographic, and pathological data, we investigated eighteen cases of early aseptic failure of an implant in patients who had undergone reconstruction of the hip with a Wagner resurfacing prosthesis. Sixteen patients required revision for loosening of the acetabular component, with eight of them also demonstrating loosening of the femoral component. One patient had loosening of the femoral component without failure of the acetabular component, and one patient sustained a femoral neck fracture that was associated with osteonecrosis. Six of the patients with loosening of the acetabular component had an associated significant loss of acetabular bone stock. Loosening was associated with the development of a membrane at the bone-cement interface in all patients. Histological examination of the membrane demonstrated a marked foreign-body response to wear products from the arthroplasty. Bone resorption appeared active at the bone-membrane interface. We concluded that the acetabular component of the Wagner prosthesis is prone to early loosening and that the early loosening is potentiated by a foreign-body response to debris resulting from arthroplastic wear.