Increased Surgical Volume Is Associated with Lower THA Dislocation Rates Todd C. Battaglia, MD, MS; Kevin J. Mulhall, MD, MCh, FRCSI(Tr&Orth); Thomas E. Brown, MD; and Khaled J. Saleh, MD, MSc(Epid), FRCSC The presumed correlation between an increasing volume of health care procedures and an improvement in outcomes is sometimes referred to as the practice-makes-perfect effect. Growing interest in outcomes-based research has led to nu- merous papers examining this relationship for various sur- gical procedures, including total hip arthroplasty. The re- sults of these studies have important implications for con- sumers, providers, and healthcare financers. Accordingly, we review the literature to date examining surgeon and hos- pital volume effects on hip arthroplasty outcomes, with a specific focus on the effects of volume on dislocation. A sys- temic review of the literature demonstrates a substantial positive association between surgical volumes and improve- ment in most THA outcomes, including dislocation; that is, increasing surgical volume is associated with lower disloca- tion rates. This correlation appears to be stronger and is more clearly established for surgeon volumes than it is for hospital volumes. Level of Evidence: Therapeutic study, level III (systematic review). See Guidelines for Authors for a complete descrip- tion of levels of evidence. The presumed correlation between an increasing volume of health care procedures and an improvement in outcomes is sometimes referred to as the practice-makes-perfect ef- fect. Since the 1970s, a number of authors have examined how the volume of services delivered by an individual provider or by a hospital relates to the effectiveness of those services. 3,10 Nearly all investigators have found a positive relationship between the two, but the majority have focused on general surgical conditions, such as coro- nary arteriography, coronary bypass graft, myocardial in- farction, inguinal hernia, carotid endarterectomy, cancer surgery, and cataract surgery. 3,7,18 Few have focused spe- cifically on orthopaedic procedures but, over the past de- cade, increasing interest in outcome-based research has led to the appearance of a number of such studies in the ar- throplasty literature. Total hip arthroplasty (THA), which is performed more than 200,000 times annually in the United States and nearly always on an elective basis, is ideal for the study of volume-outcome effects. 1,9 Determination of a relation- ship between surgical volumes and THA outcomes could have important ramifications on physician training and practice patterns, consumer choices, and health care re- source distribution. Because of this, our aim was to review the current literature evaluating the effects of surgeon and hospital volume on THA outcomes, specifically disloca- tion rates. To do so, PubMed and Medline searches were performed for all English-language articles with keyword combinations of surgical volume and total hip arthro- plasty, or surgical volume and dislocation. One hundred sixty three papers were returned, for all of which the ab- stracts were obtained and reviewed. Only 17 of those pa- pers actually addressed the parameters of interest, specifi- cally discussing the relationship between surgeon or hos- pital surgical volumes and hip replacement outcomes. Detailed analyses of the 17 papers, and of all other poten- tially useful papers referenced in those 17, yielded only three studies statistically assessing dislocation rates as a function of surgeon volume (Table 1), and only two as- sessing dislocation rates as a function of hospital volume (Table 2). Although the available studies used different inclusion, stratification, and outcome criteria, making a true meta-analysis impossible, by considering these stud- ies together with other less rigorous papers a number of important trends become evident. From the Department of Orthopaedic Surgery, University of Virginia Health Sciences Center, Charlottesville, VA. Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrange- ments, etc) that might pose a conflict of interest in connection with the submitted article. Correspondence to: Todd C. Battaglia, MD, MS, Department of Orthopaedic Surgery, New England Baptist Hospital, 125 Parker Hill Ave., Boston, MA 02120. Phone: 617-754-5800; Fax: 617-754-6443; E-mail: tcbattags@ yahoo.com. DOI: 10.1097/01.blo.0000218743.99741.f0 CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Number 0, pp. 000–000 © 2006 Lippincott Williams & Wilkins 1 Copyright ' Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.