Minimum 5-year results of modular metal-on-metal total hip arthroplasty.

This study reports minimum 5-year results of 95 hips implanted with a Pinnacle (DePuy, Warsaw, Ind) modular metal-on-metal acetabular prosthesis. Clinical scores such as the Harris Hip and Western Ontario and McMaster Universities Arthritis Index revealed excellent clinical outcomes at mean 6-year follow-up. With the use of large-diameter femoral heads, dislocation was rare, occurring in only 1 hip. Moreover, no acetabular and only 3 femoral osteolytic lesions were detected. Kaplan-Meier survivorship at 7 years after arthroplasty was 97.8% for the total hip arthroplasty construct and 100% for the acetabular shell. No unexplained pain or other complication attributable to wear debris or the metal-on-metal articulation was observed. These findings indicate that total hip arthroplasty with this specific modular metal-on-metal bearing performed well in a high-demand population at midterm follow-up.

The incidence of femoral component version change in primary THA using the S-ROM femoral component.

Although use of modular femoral components in revision total hip arthroplasty (THA) is widely accepted, many still question the need for modular versatility in primary THA. This study examined a large cohort of primary THA patients implanted with a modular S-ROM femoral component (DePuy Orthopaedics, Warsaw, Indiana) to determine the percentage of hips in which the surgeon changed version of the femoral component to increase the intraoperative stability of the THA construct and/or to maximize hip range of motion without impingement.In a group of 1000 routine, primary THAs, femoral component version was changed in 479 hips (47.9%). This change in rotational position of the femoral stem ranged from 60° retroversion with respect to the position of the sleeve to 80° of anteversion with respect to the sleeve. Ten hips (1%) experienced dislocation within the first 3 postoperative months. There was no difference in the dislocation rate between those patients in which femoral component version was changed versus those in which version was not changed. Statistical analysis showed no correlation between the likelihood of changing stem version and any of the following clinical variables: patient age, sex, diagnosis, or surgeon.The high percentage of straightforward primary THAs in which it was deemed beneficial to change version of the stem combined with the lack of correlation between femoral version change and clinical variables leads us to conclude that the routine use of a stem that allows variable version may be advantageous when compared to a nonmodular stem, as it is not possible to preoperatively determine when changing version will be required.

Influence of stem size on clinical outcome of primary total hip arthroplasty with cementless extensively porous-coated femoral components.

This study retrospectively evaluated the clinical outcome of primary total hip arthroplasty as a function of stem diameter in 1545 patients implanted with extensively porous-coated stems. Less than 2% of femoral components were loose or revised; femoral survivorship was 97.9% at 15 years. Of patients with stable components, 95 to 97% had increased function, decreased pain, and overall satisfaction. Although 17% of patients indicated activity-limiting pain, only 3% were dissatisfied with the results of their hip arthroplasty. Logistic regression demonstrated no statistical relationship between stem size and either revision, loosening, pain, or satisfaction. We conclude that patients with large-diameter, extensively porous-coated femoral components are no more likely to be revised, loose, or have thigh or activity-limiting pain than patients with smaller diameter stems.

The temporal progression of pelvic osteolysis after uncemented total hip arthroplasty.

This study examined the natural progression of pelvic osteolysis post uncemented total hip arthroplasty. Serial radiographs from 145 total hip arthroplasties with minimum 10-year follow-up were examined. Thirty-two lesions were identified in 25 hips and their 2-dimensional radiographic size over time was measured via computer. Lesion growth rate averaged 42.7 +/- 49.0 mm2/y. Linear models were generally a good fit for lesion growth as evidenced by a high mean r2 value (0.77 +/- 0.18); lesions progressed steadily during the first 10 postoperative years. Although lesions were first radiographically evident 5.7 years postarthroplasty, the x-intercept of the linear model, approximating the mean time when the lesions first began to develop, averaged 1.3 years. Because this study expands our understanding of when and how peri-acetabular lesions develop, it can be useful to clinicians in determining how often to see patients postoperatively.

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.