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Case Mix and Outcomes of Total Knee Replacement in Orthopaedic Specialty Hospitals

Katz, Jeffrey N. MD, MSc*; Bierbaum, Benjamin E. MD; Losina, Elena PhD*‡

doi: 10.1097/MLR.0b013e31816c43c8
Brief Report

Objectives: To examine patient characteristics and outcomes of total knee replacement (TKR) in orthopaedic specialty hospitals.

Methods: We performed a retrospective cohort study in the US Medicare population. We defined specialty hospitals for TKR as centers: (1) that performed >75 TKRs in Medicare recipients in 2000; (2) in which TKR accounted for >7% of all Medicare discharges; and (3) that had <300 beds. We divided specialty hospitals into those with ≤100 beds and those with 101–299 beds. We compared preoperative characteristics and complications among patients undergoing TKR in specialty and nonspecialty centers. We stratified patients according to risk of complications and performed stratum-specific analyses.

Results: A total of 2417 patients received TKA in 19 specialty hospitals, accounting for 3% of all TKRs in 2000. The specialty hospitals had fewer patients with poverty level income. The smaller “boutique” specialty hospitals had lower complication rates than the larger specialty hospitals and the nonspecialty centers (P value for trend = 0.001). In analyses that adjusted for patient age and sex, low-risk patients had similar outcomes across all hospital categories. However, high-risk patients had statistically significantly greater benefit from treatment in smaller specialty hospitals, with the risk of any adverse event ranging from 1.4% (95% CI, 0%–3.5%) in smaller specialty hospitals to 4.9% (95% CI, 4.4%–5.5%) in low-volume centers.

Conclusions: Smaller specialty hospitals have low complication rates and are especially beneficial for high-risk patients. Further work should address functional outcomes, costs, and satisfaction in these specialty centers, and evaluate strategies to manage more high-risk patients in specialty centers.

From the *Department of Orthopaedic Surgery and Division of Rheumatology, Immunology, and Allergy, Orthopaedic and Arthritis Center for Outcomes Research, Brigham and Women's Hospital, Harvard Medical School; †Department of Orthopaedic Surgery, New England Baptist Hospital, and ‡Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts.

Supported by a grant from the New England Baptist Hospital and by NIH/NIAMS grants K24 AR02123 and P60 AR 47782.

The funding organizations (New England Baptist Hospital, NIH) did not have any role in design, analysis, or reporting of findings.

Reprints: Jeffrey N. Katz, MD, MS, Orthopaedic and Arthritis Center for Outcomes Research, Brigham and Women's Hospital, OBC-4, 75 Francis Street, Boston, MA 02115. E-mail:

© 2008 Lippincott Williams & Wilkins, Inc.