Osteolysis propensity among bilateral total hip arthroplasty patients.

Because some patients with high wear rates demonstrate extensive osteolysis whereas other patients with similarly high wear rates show little or no evidence of osteolysis, we hypothesized that both polyethylene wear and a patient-specific propensity mediate the development of osteolysis. We evaluated wear and osteolysis using computed tomography and radiographs among 46 patients who had undergone bilateral total hip arthroplasties (THAs). A radiographic patient-specific propensity for osteolysis associated with each THA was quantified by dividing the amount of osteolysis by the volumetric wear. Using a multivariate regression analysis to simultaneously consider the influence of polyethylene wear and patient propensity, we found that both factors are associated with the amount of osteolysis around a THA and that they appear to be of similar importance.

A comparison of a second- and a third-generation modular cup design: is new improved?

The highly cross-linked polyethylene liners currently used with modular uncemented cups have substantially decreased wear and osteolysis at early follow-up. However, retroacetabular osteolysis has still been reported in some cases with DePuy Orthopaedic's (Warsaw, IN) second-generation Duraloc acetabular shell. DePuy's third-generation Pinnacle cup incorporates a different shell-liner locking mechanism. We compared the clinical outcome among a matched series of 42 Duraloc and 42 Pinnacle cups at a mean follow-up of 5.9 years. Although the Harris Hip Scores and wear rates were not statistically different between the 2 cup designs, retroacetabular osteolysis behind the central hole was absent among the Pinnacle cups but noted among 19% of the Duraloc cups.

Can the volume of pelvic osteolysis be calculated without using computed tomography?

UNLABELLED: The most common method to diagnose and monitor osteolysis is the standard anteroposterior radiograph. Unfortunately, plain radiographs underestimate the incidence and extent of osteolysis. CT scans are more sensitive and accurate but also more expensive and subject patients to more radiation. To determine whether the volume of pelvic osteolysis could be accurately estimated without a CT scan, we evaluated the relationships between CT volume measurements and other variables that may be related to the size of pelvic osteolytic lesions in 78 THAs. Only the area of pelvic osteolysis measured on radiographs, heavy patient activity level, and total volume of wear were associated with the pelvic osteolysis volume measured on CT in the context of the multivariate regression analysis. Despite a strong correlation (r = 0.93, r(2) = 0.87) between these three variables and the volume of pelvic osteolysis measured on CT, estimates of pelvic osteolysis volume deviated from the actual volume measured on CT by more than 10 cm(3) among eight of the 78 THAs in this study. CT images remain our preferred modality when accurate assessments of pelvic osteolysis volume are required. LEVEL OF EVIDENCE: Level III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Results of the anatomic medullary locking total hip arthroplasty at a minimum of twenty years. A concise follow-up of previous reports.

Between October 1982 and December 1984, the senior author performed 223 total hip arthroplasties in 215 patients with use of the anatomic medullary locking hip stem and TriSpike cup. We now report on 119 of these hips at a mean of 22.0 years (range, 20.0 to 25.0 years) after surgery. Of the fifty-six hips with minimum twenty-year follow-up radiographs and the original acetabular component, seventeen (30.4%) had pelvic osteolytic lesions measuring larger than 1.5 cm(2). Of the sixty-eight hips with twenty-year radiographs and the original anatomic medullary locking stem, twenty-five (36.8%) had femoral osteolytic lesions measuring larger than 1.5 cm(2). Acetabular osteolysis was significantly associated with cup loosening (p = 0.006), but the presence of femoral osteolysis was not associated with stem loosening. Kaplan-Meier analysis, with revision for any reason as the end point, revealed that the survival rate at twenty years was 85.8% +/- 5.2% for the acetabular shell and 97.8% +/- 2.2% for the stem. The most common reoperation was polyethylene exchange because of wear or osteolysis.

Incidence and volume of pelvic osteolysis at early follow-up with highly cross-linked and noncross-linked polyethylene.

Highly cross-linked polyethylene has shown decreased wear rates as compared to conventional polyethylene. However, the impact of this decrease on the occurrence of osteolysis remains uncertain. Forty hips implanted with noncross-linked Enduron and 36 implanted with 5-Mrad cross-linked Marathon polyethylene had a computed tomography at a minimum of 5 years after arthroplasty. Polyethylene wear, osteolysis incidence, location, and volume were compared. The incidence of osteolysis was statistically greater for patients with noncross-linked Enduron (11/40, 28%) compared to patients with the moderately cross-linked Marathon (3/36, 8%; P = .04). The average lesion volume for hips with Enduron liners (7.5 +/- 6.7 cm(3)) was significantly greater than the average lesion volume for hips implanted with Marathon liners (1.2 +/- 0.1 cm(3), P = .01). Marathon cross-linked polyethylene has shown to have a decreased incidence and volume of pelvic osteolysis. Longer follow-up is necessary to determine if Marathon cross-linked polyethylene will continue to demonstrate the encouraging improved wear and osteolysis characteristics.

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.

Acetabular fixation options: first-generation modular cup curtain calls and caveats.

This study reviewed the outcome of a single institution's experience with 910 primary total hip arthroplasties using 3 different types of modular, first-generation, hemispheric porous-coated cups. The population included 433 Arthopor, 394 ACS Triloc+, and 83 Harris-Galante components. Among 168 total hip arthroplasties that have undergone acetabular revision, aseptic loosening has occurred in 20 cases. Using liner or cup revision for any reason as an end point, we found that 15-year survivorship was 74.9% +/- 6.2% (95% confidence interval) for the Arthopor cups, 70.1% +/- 7.0% for the ACS Triloc+ components, and 89.3% +/- 10.3% for the Harris-Galante cups (P = .02, log rank). Despite a high incidence of revision for polyethylene wear-related complications and occasional late porous-coating delamination, survivorship using revision for aseptic loosening as an end point exceeded 95% at 15 years for all 3 cup designs.

A randomized prospective evaluation of outcomes after total hip arthroplasty using cross-linked marathon and non-cross-linked Enduron polyethylene liners.

Cross-linked liners were introduced with the promise that they would substantially reduce polyethylene wear. In 1999, our institution initiated a prospective study to compare the outcome of total hip arthroplasty patients who were randomized to non-cross-linked Enduron liners with that of total hip arthroplasty patients who were randomized to Marathon polyethylene liners that had been cross-linked with 5 Mrad (50 kGy) of gamma-irradiation and heat-treated to eliminate free radicals. At a mean follow-up of 5.7 years, the clinical outcomes among the Marathon and Enduron liners were similar. However, the mean wear rate was 0.01 +/- 0.07 mm/y for the Marathon group, which represents a 95% reduction compared with the mean wear rate of 0.19 +/- 0.12 mm/y for the Enduron group. In addition, the incidence of osteolysis was lower in the Marathon group.