A cost comparison of unicompartmental and total knee arthroplasty.

Background: Unicompartmental knee arthroplasty (UKA) is an alternative to total knee arthroplasty (TKA) in appropriately selected patients. There is a paucity of data comparing hospital resource utilization and costs for UKA versus TKA.

Methods: We retrospectively reviewed 128 patients who underwent UKA or TKA for osteoarthritis by a single surgeon in the 2011 Fiscal Year. Sixty-four patients in each group were matched based on sex, age, race, body mass index, Charlson Comorbidity Index, and insurance type. Clinical data were obtained from medical records while costs were obtained from hospital billing. Bivariate analyses were used to compare outcomes.

Results: Both anesthesia and operative time (minutes) were significantly shorter for patients undergoing UKA (125.7 vs. 156.4; p<0.001, and 81.4 vs. 112.2; p<0.001). UKA patients required fewer transfusions (0% vs. 11.0%; p=0.007) and had a shorter hospital stay (2.2 vs. 3.8days; p<0.001). 96% of UKAs were discharged home compared with 75% of TKAs (p<0.001). Hospital direct costs were lower for UKA ($7893 vs. $11,156; p<0.001) as were total costs (hospital direct costs plus overhead; $11,397 vs. $16,243; p<0.001). Supply costs and implant costs were similarly lower for UKA ($701 vs. $781; p<0.001, and $3448 vs. $5006; p<0.001).

Conclusion: Our data suggest that UKA provides a cost-effective alternative to TKA in appropriately selected patients. As the number of patients with end-stage arthritis of the knee requiring surgical care continues to rise, the costs of caring for these patients must be considered.

Level Of Evidence: Level III, case control study.