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Clinical Issues Summary

Dr. Sculco is Surgeon in Chief, Hospital for Special Surgery, New York, NY. Dr. Callaghan is the Lawrence & Marilyn Dorr Chair in Hip Reconstruction & Research, Professor of Orthopaedics, Rehabilitation & Biomedical Engineering, University of Iowa, and Staff Orthopaedic Surgeon, Veterans Affairs Medical Center, Iowa City, IA. Dr. Galante is The Grainger Director, Rush Arthritis and Orthopedic Institute, Rush-Presbyterian-St. Luke’s Medical Center, and Professor of Orthopedic Surgery, Department of Orthopedic Surgery, Rush Medical College, Rush University Medical Center, Chicago, IL.

*The Implant Wear Symposium 2007 Clinical Work Group included John J. Callaghan, MD, John M. Cuckler, MD, Jorge O. Galante, MD, DMSc, Alejandro González Della Valle, MD, Stuart B. Goodman, MD, PhD, James I. Huddleston, MD, Lynne C. Jones, PhD, David G. Lewallen, MD, Henrik Malchau, MD, PhD, William Maloney, MD, Amanda Marshall, MD, Wayne Paprosky, MD, Hollis G. Potter, MD, Michael D. Ries, MD, Aaron Rosenberg, MD, Thomas P. Sculpco, MD, Bernard N. Stulberg, MD, Audrey K. Tsao, MD, and Timothy Wright, PhD.

Dr. Sculco or a member of his immediate family has received research or institutional support from Exactech, Smith & Nephew, and Zimmer. Dr. Callaghan or a member of his immediate family has received research or institutional support, miscellaneous nonincome support, commercially derived honoraria, or other nonreseach-related funding, and royalties from DePuy and is a consultant for DePuy. Dr. Galante or a member of his immediate family has received research or institutional support and royalties from Zimmer.

Diagnosis and surveillance of wear-induced osteolysis include measurements of wear to assess the extent of the generation of wear debris and imaging methods to assess the extent, location, and progression of the periprosthetic osteolysis process. To this end, methods such as radiographic edge detection, spiral computed tomography, magnetic resonance imaging, as well as radiographic stereometric analysis (in selected patient cohorts), and quantitation of wear and osteolysis (including bone and soft-tissue lesions) are necessary. In particular, the use of computed tomography and magnetic resonance imaging in diagnosing the extent of osteolysis should be extended to large cohorts to examine the efficacy of these diagnostic tools and to establish guidelines for their clinical use in the evaluation of new hip and knee replacement designs. There is an ongoing need for techniques to measure wear in total knee arthroplasty cases.

With regard to treatment, ongoing surveillance may be appropriate for very small, nonprogressive osteolytic lesions in noncritical areas. However, surgical management of progressive wear-associated osteolytic lesions is indicated, as pharmacologic treatments have not been successful. Standardized methods to measure the extent of wear and osteolysis and to assess the outcome of bone grafting and other treatments are being developed. Surgical intervention must address the wear-particle generator, the osteolytic defects, and implant-related issues such as fixation and alignment. Patient age and activity level, the location and size of the osteolytic defects, and the clinical record of the implant system should be considered. Surgical treatment must be individualized. Such treatment varies, from débridement with changing worn bearing surfaces with or without bone grafting of osteolytic lesions, to more extensive procedures that replace the entire prosthesis and restore structural bone loss. Simpler, less extensive procedures should be considered when the implants have a good track record and exhibit satisfactory alignment and when high-quality replacement parts are readily available. Better devices for extracting malfunctioning prostheses are available to limit bone loss. Prospective standardized multicenter trials using defined treatment protocols are required to improve the level of evidence of revision procedures.

Second-generation cementless implants have shown excellent durability of fixation up to 15 to 20 years. Early clinical success with very low rates of wear and osteolysis has been shown with all three couples of alternative bearings for hip replacement (metal-on-metal, highly cross-linked polyethylene, ceramic-on-ceramic). However, the data are based on short-term follow-up. Because of the minimal amount of wear present, there is a need for the development of monitoring techniques for hard bearings and for the knee. The expectation from these early observational data is that wear and the resulting loosening and aggressive bone loss will not be observed on long-term follow-up.

All three bearing couples are very sensitive to surgical technique and, specifically, to proper acetabular positioning. This is at the root of the early complications that have been reported: fracture of the implant (cross-linked polyethylene); squeaking and impingement wear (ceramic-on-ceramic bearings); and runaway wear, osteolysis, and immune system–related complications (metal-on-metal bearings). These problems may be complicated by the use of minimally invasive techniques that do not afford adequate visualization, particularly in the hands of the less experienced surgeon.

There is a need to establish the relative indications and contraindications for the choice of one bearing couple over another. There are no definitive guidelines to help the practicing surgeon other than those provided by commercial interests because no system has shown clear superiority over the others. Less information is available concerning the use of highly cross-linked polyethylene in the knee, where the experience is shorter term and the mechanical environment is more demanding. Thus, prospective, randomized, multicenter long-term studies comparing the different available bearings are needed, particularly in young and active patient populations. Furthermore, a national arthroplasty registry will be of unique value to establish effectiveness of the different bearings among the general population.

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Sculco, T. P. Articles by Galante, J. O. Search for Related Content PubMed Articles by Sculco, T. P. Articles by Galante, J. O.