Surgical management of polyethylene wear and pelvic osteolysis with modular uncemented acetabular components

Outcome and Risk Factors Associated with Failures of Isolated Bearing Exchange for Osteolysis in Well-Fixed Cementless Total Hip Arthroplasty

BACKGROUND

It is often challenging to decide whether to revise only the bearing or femoral acetabular component in the setting of progressive osteolysis without component loosening in revision total hip arthroplasty (THA). In this study, we aimed to (1) compare the survivorship of isolated bearing exchange and single/both component revision for patients with periprosthetic osteolysis without component loosening, and (2) identify potential risk factors associated with failures of isolated bearing exchange.

METHODS

A total of 228 consecutive cases of revision THA for progressive osteolysis without component loosening was evaluated in 2 groups: (1) 124 component revision and (2) 104 isolated bearing exchange. The primary outcome was survival, with failure defined as repeat revision or reoperation for any reason. Patient risk factors, such as demographics and medical comorbidities, were also analyzed.

RESULTS

There was no significant difference in survivorship between the component revision group and the bearing exchange group at 10 years (85% vs 82%; P = .89). There was no progression of osteolysis on radiographs at last follow-up for patients with isolated bearing change. Univariate regression modeling demonstrated that renal disease was associated with failure of isolated bearing exchange after revision THA.

CONCLUSION

This study demonstrated that isolated bearing exchange is associated with similar outcomes compared with component revision for aseptic osteolysis without loosening, demonstrating that isolated bearing exchange is a viable option for selected patients with osteolysis in the setting of well-fixed THA components. This provides clinically useful information for surgeons in the surgical treatment of THA patients with wear and osteolysis without component loosening.

Isolated Acetabular Liner Exchange for Polyethylene Wear and Osteolysis with Well-Fixed Metal Shell

Background

The isolated liner and head exchange procedure has been an established treatment method for polyethylene wear and osteolysis when the acetabular component remains well fixed. In this study, the mid-term results of this procedure were evaluated retrospectively.

Methods

Among the consecutive patients operated on from September 1995, two patients (three hips) were excluded because of inadequate follow-up, and the results of remaining 34 patients (34 hips) were evaluated. There were 20 men and 14 women with a mean age of 49 years. A conventional polyethylene liner was used in 26 cases and a highly cross-linked polyethylene liner was used in eight cases. In three cases, the liner was cemented in a metal shell because a compatible liner could not be used.

Results

After a follow-up of 5 to 20.2 years, re-revision surgery was necessary in 10 cases (29.4%): in eight for wear and osteolysis at 55 to 101 months after liner exchange and in two for acetabular loosening at 1 and 1.5 years after liner exchange. Re-revision surgery included all component revision (four cases), cup revision (four cases), and liner exchange (two cases). In all re-revision cases, a conventional polyethylene liner was used initially. There was no failure in the cases in which a highly cross-linked polyethylene liner was used.

Conclusions

The results of this study suggest that isolated acetabular liner exchange is a reasonable option for wear and osteolysis when the metal shell is well fixed. More promising long-term results are expected with the use of highly cross-linked polyethylene liners.

Osteolysis as it Pertains to Total Hip Arthroplasty

Osteolysis is a long-term complication of total hip arthroplasty (THA). As the projected number of THAs performed annually increases, osteolysis will likely continue to occur. However, because of advancements in prosthesis design, metallurgy, and enhanced bearing surfaces, fewer revision THAs will be linked to osteolysis and aseptic loosening. Despite these improvements, no preventative therapies are currently available for the management of osteolysis other than removing and replacing the source of bearing wear.

The Exeter V40 cemented femoral component at a minimum 10-year follow-up: the first 540 cases

Aims

The aim of this study was to report the initial results of the Exeter V40 stem, which became available in 2000.

Patients and Methods

A total of 540 total hip arthroplasties (THAs) were performed in our unit using this stem between December 2000 and May 2002. Our routine protocol is to review patients postoperatively and at one, five, and ten years following surgery.

Results

A total of 145 patients (26.9%) died before ten years and of the remaining 395 stems, 374 (94.7%) remain in situ. A total of 21 well-fixed stems (5.3%) were revised. Ten were exchanged using a cement-in-cement technique to facilitate acetabular revision. Three were revised for infection, one for instability, one for fracture of the stem, and six following a periprosthetic fracture. An additional 16 acetabular components (4.1%) were revised; five for aseptic loosening and 11 for instability. There were no revisions for aseptic loosening of the stem, and no evidence of aseptic loosening in any hip. The fate of every stem is known and all patients remain under review. Survivorship, with revision of the stem for aseptic loosening as the endpoint, was 100%. At 13.5 years, the Kaplan-Meier survival rate for all-cause revision of the stem was 96.8% (95% confidence interval (CI) 94.8 to 98.8) and all-cause revision (including acetabular revision, infection, and instability) was 91.2% (95% CI 88.3 to 94.1).

Conclusion

Conclusion No stem was revised for aseptic loosening in this series. The contemporary Exeter V40 stem continues to perform well, and survival has remained comparable with that of the Exeter Universal stem. Cite this article: Bone Joint J 2018;100-B:1002-9.

Isolated Head and Liner Exchange in Revision Hip Arthroplasty

As the number of primary total hip arthroplasties increases, so does the burden of revision procedures. The decision to revise well-fixed components in the setting of polyethylene wear and osteolysis is controversial. Modular head and liner exchange offers the advantages of reduced invasiveness, faster recovery, and bone preservation. These advantages come at the expense of higher rates of revision surgery for instability. Using the native locking mechanism for securing the new liner is preferred; however, cementing a liner into a well-fixed acetabular component is a practical alternative. The use of bone allograft or bone graft substitute for areas of osteolysis is controversial. In the setting of osteolysis, outcomes associated with the use of highly cross-linked polyethylene liners have been better than those associated with the use of conventional polyethylene; therefore, thinner liners and larger femoral heads can be used and reduce the risk of instability.

Comparison of Polyethylene Wear before and after Hip Revision with Liner Exchange Fixed with the Original Locking Mechanism

Objective

To compare the wear of conventional ultra-high molecular weight polyethylene (CUHMWPE) and highly cross-linked polyethylene (HCLPE) in hip revision with liner exchange fixed with original locking mechanism using analysis of history medical data.

Methods

From Jan. 1, 2000, to Dec. 31, 2007, 26 patients (with 29 involved hips) underwent liner exchange revision fixed with the original locking mechanism due to wear of CUHMWPE and/or osteolysis. The mean age was 53 ± 9 years at the time of the primary total hip arthroplasty (THA) and 64 ± 9 years at the revision. The exchanged liners (Marathon, Depuy) were made of HCLPE. Annual X-rays were used to measure linear wear and osteolysis. The annual linear penetration was measured using PolyWare® software (Draftware Inc.). Annual Harris Hip Scores(HSS) were recorded.

Results

The mean follow-up time between the primary and revision THAs was 11 ± 2 years and 8 ± 2 years after revision. The mean Harris Hip Score(HHS) before primary THA, 1 year after primary THA, before revision and 1 year after revision was 43±5, 85±5, 71±6, 83±7 individually. The mean penetration of the CUHMWPE and HCLPE liners occurring in the first year were 0.44 ± 0.28 mm and 0.38 ± 0.14 mm, respectively (p = 0.211). The mean annual linear penetration of CUHMWPE and HCLPE from the second year onward were 0.29±0.09 mm and 0.08 ± 0.03 mm respectively (p <0.01). All THAs with CUHMWPE showed osteolysis on acetabular and/or femoral side before revision. No HCLPE liner showed osteolysis at the last follow-up. Conclusion: The CUHMWPE liner had a significantly higher wear rate than did the HCLPE liner. The HCLPE liner showed a satisfactory liner penetration rate after revision with isolated liner exchange fixed with the original locking mechanism.

Cemented liner exchange with bone grafting halts the progression of periacetabular osteolysis

The aims of this were to examine the effect of acetabular liner exchange and intra-operative bone grafting surgery on peri-prosthetic osteolysis. Seven patients with well-fixed Harris-Galante-1 acetabular components received cemented exchange liners for worn liners associated with pre-operatively CT-quantified osteolysis. During surgery, accessible osteolytic lesions were debrided and bone-grafted. Except for one patient with recurrent dislocation and acetabular component revision, the other patients had CT scans at a median of 4 months and at approximately 4 years after surgery. None of the pre-operative lesions increased in volume during the post-operative reporting period and no new lesions were detected. These results show that cemented liner exchange surgery can halt the progression of osteolysis and that bone grafting has the potential to restore bone.

Characterization of progression of pelvic osteolysis after cementless total hip arthroplasty: computed tomographic study

A retrospective analysis of 63 primary total hip arthroplasty cases was done using repeated computed tomography scans to evaluate the pelvic osteolytic lesions in early stage. The progression rate of osteolysis of hips with small osteolytic volume less than 766.97 mm(3) in initial CT was 85.82 mm(3)/year, and that of hips with osteolysis more than 766.97 mm(3) was 456.3 mm(3)/year (P < 0.001). Younger patients less than 52 years old with good Harris Hip Scores (more than 80) frequently showed much faster progression in volume of osteolytic lesions. The rate of osteolysis was accelerated when the amount of osteolysis reached a certain threshold volume in active young patients in a cascade manner even in early stage.

Computed tomography vs. digital radiography assessment for detection of osteolysis in asymptomatic patients with uncemented cups: a proposal for a new classification system based on computer tomography

Digital radiographic images in the anterior-posterior and lateral view have been gold standard for evaluation of peri-acetabular osteolysis for patients with an uncemented hip replacement. We compared digital radiographic images and computer tomography in detection of peri-acetabular osteolysis and devised a classification system based on computer tomography. Digital radiographs were compared with computer tomography on 206 hips, with a mean follow up 10 years after surgery. The patients had no clinical signs of osteolysis and none were planned for revision surgery. On digital radiographs, 192 cases had no osteolysis and only 14 cases had osteolysis. When using computer tomography there were 184 cases showing small or large osteolysis and only 22 patients had no osteolysis. A classification system for peri-acetabular osteolysis is proposed based on computer tomography that is easy to use on standard follow up evaluation.

Large-diameter metal-on-metal total hip arthroplasties: a page in orthopedic history?

Large-diameter metal-on-metal (MoM) bearings evolved from the success of hip resurfacing. These implants were used in revision surgery in cases with well-fixed acetabular cups but loose or failed femoral stems, to avoid cup revision. Early data showed low rates of dislocation and potentially low wear profiles due to better fluid film lubrication. The risk of impingement was also thought to be low due to the increased head-neck ratio. Subsequently large-diameter MoM heads gained popularity in primary hip replacement. Recent data has emerged on the unacceptably high revision rates among patients with large-diameter MoM total hip arthroplasties (THAs), high blood levels of metal ions, and adverse tissue reactions. The head-neck (cone-taper) modular interface probably represents the weak link in large metal heads that have been used on conventional tapers. Increased torque of the large head, micromotion, and instability at the cone-taper interface, synergistic interactions between corrosion and wear, edge loading, low clearance, and psoas impingement are the likely causes for early failure of these prostheses.

Percutaneous acetabuloplasty: a cadaveric study

Periacetabular osteolysis is a common etiology of prosthesis failure in patients who undergo total hip arthroplasty. These lesions are treated by open and, more recently, percutaneous techniques. The purpose of this study was to determine the relevant surface anatomy and bony landmarks in establishing percutaneous access to periacetabular regions and identifying critical at-risk structures in establishing access. Percutaneous access to the periacetabular region was established superiorly, anteroinferiorly, and posteroinferiorly by using 5 L5-to-mid thigh fixed cadaver pelvises with latex-injected vessels using threaded guidewires. Dissection was completed to identify structures at risk, with the distance from the wires recorded to the nearest millimeter. C-arm position for the optimal visualization and placement of guidewires was recorded. Average distance from the pin and the at-risk structures ranged from 11.2 to 38.7 mm. All 3 approaches allowed for safe percutaneous access to the periacetabular regions without injuring significant anatomical structures. This study established safe starting points and orientation for guidewires and radiograph projections associated with percutaneous access to the periacetabular regions. The findings in this study will be useful for developing minimally invasive approaches to these regions for the treatment of osteolytic lesions of diverse etiology. However, a biomechanical evaluation of the impact of these bony channels on the strength of pelvis under physiological and unanticipated loading must be performed before this technique can be safely translated to clinical practice.

Reconstruction options for acetabular revision

This article summarizes reconstruction options available for acetabular revision following total hip arthroplasty. A thoughtful methodology to the evaluation and treatment of patients with implant failure after joint replacement is essential to guarantee accurate diagnoses, appropriate triage to reconstruction options, and optimal clinical outcomes. In the majority of patients who undergo acetabular revision, factors such as bone loss and pelvic discontinuity provide a challenge in the selection and implementation of the proper reconstruction option. With advanced evaluation algorithms, imaging techniques, and implant designs, techniques have evolved to rebuild the compromised acetabulum at the time of revision surgery. However, clinical outcomes data for these techniques continue to lag behind the exponential increase in revision hip arthroplasty cases predicted to occur over the next several years. We encourage those involved in the treatment of patients undergoing hip replacement surgery to participate in well-designed clinical studies to enhance evidence-based knowledge regarding revision acetabular reconstruction options.

Retention of a well-fixed acetabular component in the setting of acetabular osteolysis

PURPOSE

The treatment strategy for pelvic osteolysis with a well-fixed acetabular component after total hip arthroplasty(THA) involves replacing the acetabular cup liner and femoral head, débriding osteolytic lesions, and grafting.

METHODS

We investigated whether retention of a well-fixed acetabular component using the two-approach technique—the ilioinguinal approach combined with the posterolateral approach—was compatible with socket survival. Were viewed clinical and radiographic findings for 24 patients(24 hips) who had undergone acetabular revision arthroplasty of a well-fixed socket for progressive osteolysis. The surgical techniques used included osteolytic lesion débridement and bone grafting through the ilioinguinal approach,and replacement of the acetabular liner and femoral head through the posterolateral approach.

RESULTS

The mean duration of follow-up after revision was 2.3 (range 2.1–3.9) years. At follow-up evaluation, all acetabular components were well fixed and showed no evidence of loosening, osseous integration was apparent and there was no radiographic evidence that any lesions had progressed. No new osteolytic lesions were identified, and there were no clinical or radiographic complications.

CONCLUSIONS

Curettage and bone grafting under direct vision, cup liner and femoral-head replacement because of progressive retroacetabular osteolysis and retention of well fixed components using the two-approach technique results in good osseous integration of lysis. Larger studies with longer follow-up periods are required to establish the longterm success of this technique.

Complete acetabular cup revision versus isolated liner exchange for polyethylene wear and osteolysis without loosening in cementless total hip arthroplasty

INTRODUCTION

Revision surgery in patients showing polyethylene wear and acetabular osteolysis without visible acetabular cup loosening involves the difficult decision of whether to revise only the liner or both the cup and the liner. The purpose of this study is to compare the outcomes of complete acetabular revision and isolated liner exchange in patients showing wear and osteolysis without loosening.

MATERIALS AND METHODS

We evaluated 80 cases of revision surgery for polyethylene wear and osteolysis without cup loosening performed between October 1997 and December 2008. The cup revision group consisted of 45 patients who underwent a complete acetabular cup replacement, and the cup retention group consisted of 35 patients who underwent either an isolated liner exchange or a liner cementing procedure. Comparisons between the two groups were performed.

RESULTS

There were differences in femoral stem revision, estimated blood loss, and hospital stay. Other variables including complications, osteolysis progression, re-revision rate, clinical score, and satisfaction showed no differences between the two groups. There was one case of early loosening and subsequent re-revision surgery in the cup revision group, as well as one case of wear progression and liner dislodgement leading to complete re-revision of the acetabular component and femoral stem in the cup retention group.

CONCLUSION

We found no differences in acetabular osteolysis progression, fixation failure, or complication between the cup revision and retention groups. Therefore, isolated liner exchange without cup extraction in cases of osteolysis that includes a well-fixed and well-positioned shell could be considered as a viable treatment option.

Liner exchange and bone grafting: rare option to treat wear & lysis of stable TKAs

BACKGROUND

Liner exchange and bone grafting are commonly performed for wear and osteolysis around well-fixed modular acetabular components that otherwise would require structural allografting and revision THA. However, liner exchange in the face of substantial lysis around TKA has been performed rarely with reports of failure rates of up to 25% at 3 year followup.

QUESTIONS/PURPOSES

We therefore evaluated the technique of liner exchange and bone grafting for cases of wear and extensive osteolysis around TKAs in which the components were well-fixed and well-aligned to determine (1) rerevision rates; (2) fate of the bone graft; (3) radiographic loosening rates; and (4) functional scores.

METHODS

We retrospectively reviewed 22 patients (25 knees) who underwent revision TKA with exchange of the modular polyethylene insert and bone grafting in cases with well-fixed components and large areas of osteolysis (up to 54 cm(2) on a single projection) at the time of revision. The average area of osteolysis was 21 cm(2) and 10 cm(2) on the AP projection of the femur and tibia, respectively. On the lateral projection, the average area of osteolysis for the femur and tibia was 22 cm(2) and 9.3 cm(2). Minimum clinical and radiographic followup was 22 and 22 months (average, 61 and 59; range, 22-142 and 22-130, respectively).

RESULTS

One of the 25 knees was revised for aseptic loosening or recurrence of osteolysis. On radiographs, 84.6% and 70% of femoral and tibial osteolytic lesions, respectively, showed evidence of complete or near complete graft incorporation. The remaining lesions showed evidence of partial graft incorporation with the exception of one tibial lesion, which was in the revised case. All other components were well fixed with no evidence of radiographic loosening.

CONCLUSIONS

In this selected series of cases with extensive osteolysis around well-fixed and well-aligned TKAs, liner exchange and bone grafting provided durable midterm results with extensive graft incorporation.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

A three-dimensional method for evaluating changes in acetabular osteolytic lesions in response to treatment

The treatment of asymptomatic osteolysis among well-fixed cementless cups remains controversial. To compare the effectiveness of different treatment strategies, an objective technique for evaluating bone remodeling would be useful. By matching and comparing serial CT images with the aid of a computer-assisted imaging program, we developed a method to evaluate three-dimensional mineralization changes within osteolytic defects. Preoperative, immediate postoperative, and followup CT images were normalized based on a phantom with known densities and matched using image registration so that the same region could be analyzed on each image. New bone mineralization within the preoperative osteolytic lesion volume was quantified based on a patient-specific trabecular bone density threshold. As a pilot study, we applied this technique in 10 patients treated by polyethylene liner exchange with débridement and grafting of periacetabular osteolytic lesions using a calcium sulfate bone graft substitute. Relative to the preoperative osteolytic lesion volume, an average of 43% (range, 8%-72%) of each defect was filled with graft at revision. After resorption of the graft, an average of 24% (range, 9%-44%) of the original defect volume demonstrated evidence of new mineralization at 1-year followup. The amount of new mineralization was directly proportional (r(2) = 0.70) to the defect filling achieved at revision. CT-based image analysis offers an objective method for quantifying three-dimensional bone remodeling and can be used to evaluate the effectiveness of osteolysis treatment strategies.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Surface Roughness of CoCr and ZrO(2) Femoral Heads with Metal Transfer: A Retrieval and Wear Simulator Study

Metal transfer to femoral heads may result from impingement against the metallic acetabular shell following subluxation/dislocation, or when metallic debris enters the articulation zone. Such transfers roughen the head surface, increasing polyethylene wear in total hip replacements. Presently, we examined the surface roughness of retrieved femoral heads with metallic transfer. Profilometry revealed roughness averages in regions of metal transfer averaging 0.380 μm for CoCr and 0.294 μm for ZrO₂ which were one order of magnitude higher than those from non-implanted controls. Scanning electron microscopy (SEM) revealed adherent transfers on these retrievals, with titanium presence confirmed by electron dispersive spectroscopy. Due to the concern for increased wear, metal transfer was induced on non-implanted heads, which were then articulated against flat polyethylene discs in multidirectional sliding wear tests. Increased polyethylene wear was associated with these specimens as compared to unaltered controls. SEM imaging provided visual evidence that the transfers remained adherent following the wear tests. Pre- and post-test roughness averages exceeded 1 μm for both the CoCr and ZrO₂ heads. Overall, these results suggest that metal transfer increases the surface roughness of CoCr and ZrO₂ femoral heads and that the transfers may remain adherent following articulation against polyethylene, leading to increased polyethylene wear.

Retroacetabular osteolytic lesions behind well-fixed prosthetic cups: pilot study of bearings-retaining surgery

Background

Osteolytic lesions are common radiological findings behind acetabular prosthetic cups. If the cup is well-fixed, the management is quite controversial. Although implant exchange is the most reliable procedure, in most cases it could be considered overtreatment, with the potential for further morbidity and bone loss. Liner exchange associated with lesion debridement and grafting represents an alternative option that is less invasive. Here we present our experiences from a small pilot study of minimally invasive osteolysis treatment without bearings exchange in patients with no evidence of liner wear.

Materials and methods

Inclusion criteria: retroacetabular osteolytic lesions in ceramic-on-polyethylene or metal-on-polyethylene cementless total hip arthroplasties, affecting more than 50% of the bone–prosthesis interface on anteroposterior radiography. Exclusion criteria: head penetration into the liner, suspected loosening or infection. Six patients were selected, two asymptomatic and four symptomatic. Only the symptomatic patients accepted the proposed treatment (performed between June 2004 and March 2006). All of them received fluoroscopy-assisted lesion debridement through an iliac cortical window, morcellized bone allograft mixed with autologous platelet-rich plasma, joint exploration for culture and lavage through a small capsular window. Patients were followed up clinically and radiologically at six months, 12 months, and then yearly.

Results

Three patients out of four showed clinical and radiological improvement. One showed radiological improvement only, and recently underwent cup exchange for subsequent loosening. The visual analog scale (VAS) values for pain decreased on average, but not significantly. No major complications occurred. No recurrence was noted at 2.25–4 years’ follow-up.

Conclusions

Although the small series does not allow any absolute conclusions to be drawn, the reported results seem to justify further, wider studies. It is still unclear if osteolytic lesions associated with no wear of the poly liner would progress to implant failure if left untreated. Until the problem is better understood, this procedure might represent an interesting way to prevent potential loosening and severe bone loss in intact sockets.

The quality of osteolysis grafting with cementless acetabular component retention

Periprosthetic osteolysis is a common cause for revision of total hip arthroplasty. When modular cementless acetabular components are stable, curettage and grafting of the osteo-lytic lesion while retaining the component are a good surgical option. Although the midterm outcome of this procedure is known, the quality of the surgical technique is not. We used preoperative and postoperative computed tomography to determine the percentage of periacetabular lesions that was grafted and the percentage of the lesion volume filled with an injectable bone graft substitute. We discovered, even with preoperative computed tomography reconstructions and surgical planning, four of 22 lesions were neglected at the time of surgery. In the 18 lesions that were treated, we were able to fill an average of 49% (range, 0-83%) of the lesion volume. These inconsistent results illustrate a need to further refine surgical techniques and instrumentation to treat one of the most common complications in total hip arthroplasty. Longer followup with repeat computed tomography scans or other imaging techniques would determine if the percentage of lesion fill has an effect on clinical outcome.

Unilateral tibial polyethylene liner failure in bilateral total knee arthroplasty--bilateral retrieval analysis at 8 years

This is a report of a unique case of bilateral simultaneous total knee arthroplasties in which one tibial liner failed dramatically, whereas the other liner showed minimal evidence of wear. This unique case allows isolation of component factors as the primary contributing etiology to failure. The differentiating characteristic was the method of sterilization and the shelf life of the polyethylene liner. The insert that showed minimal wear was sterilized with gamma radiation in a barrier package and had a shelf life of less than 1 year, whereas the insert that failed dramatically was sterilized in air and had a shelf life of more than 5 years. This case provides a dramatic example of the potential detrimental effects of manufacturing details on the performance of orthopedic implants, particularly polyethylene inserts.

Larger diameter bearings reduce wear in metal-on-metal hip implants

Metal-on-metal hip arthroplasty has the longest clinical history of all total arthroplasties. We asked whether large diameter femoral heads would result in less wear than those with small diameters. We also asked if there is a threshold diameter that ensures good wear behavior. We tested three batches of cast high-carbon cobalt-chromium-molybdenum hip implants (28 mm, 36 mm, and 54 mm diameters) in a hip simulator for 5 million cycles. We used bovine serum as lubricant and weighed the samples at regular intervals during testing. The 28-mm configuration had almost twice the wear of the 54-mm configuration, but we observed no difference between the 36-mm and the 54-mm configurations. The similarity in the wear performances of the larger configurations supports the presence of a threshold diameter that ensures good wear behavior.

Computed tomographic follow-up evaluation of operative intervention for periacetabular lysis

Computed tomography (CT) accurately evaluates periacetabular lytic lesions. The purpose of this study is to determine the fate of osteolytic lesions after treatment with liner exchange and bone grafting. Fifteen patients who had undergone liner exchange with grafting for progressive lytic lesions, as demonstrated by preoperative CT scans, were identified. Postoperative CT scans were performed at a minimum of 2 years post revision. The largest cross sectional lytic area was compared with the postoperative scan to determine the fate of the lesion. The mean size of the measured lytic lesions preoperatively was 6.38 cm(2). Postoperatively, lesions decreased to 2.94 cm(2) (P = .000). Modular liner exchange with grafting is effective in treating osteolytic lesions in the pelvis, as demonstrated by CT.