Hospital cost structure and resource utilization in unicompartmental knee arthroplasty and hip resurfacing arthroplasty: a single-center comparative cost analysis.

Abstract

Introduction: Unicompartmental knee arthroplasty (UKA) and hip resurfacing arthroplasty (HRA) are joint-preserving procedures used in different anatomical and clinical settings. Although they are not competing treatment options, both require substantial hospital resources. This study compared institutional cost structure and resource utilization associated with UKA and HRA from the hospital-provider perspective.

Methods: This retrospective, single-center study included 68 unique patients undergoing UKA (n = 36) or HRA (n = 32) between January 2023 and July 2024. Each patient contributed one index hospitalization, one surgical procedure, and one independent analytical observation. The primary outcome was total index-hospitalization cost. Secondary outcomes included operating-room personnel costs, costs incurred outside the operating room, medical costs, and non-medical costs. Individual cost components and correlations with length of stay were exploratory. The association between procedure type and total index-hospitalization cost was assessed using a gamma-log generalized linear model adjusted for age, sex, body mass index, Charlson Comorbidity Index, and Kellgren-Lawrence grade 4. Secondary and exploratory comparisons were adjusted using the Benjamini-Hochberg false-discovery-rate procedure.

Results: Mean total index-hospitalization cost was €5,561.53 for UKA and €6,631.18 for HRA, an unadjusted difference of €1,069.65 (p < 0.0001). After case-mix adjustment, HRA was associated with a 32% higher expected total index-hospitalization cost than UKA (adjusted cost ratio 1.32, 95% CI 1.07-1.63; p = 0.008). Medical costs were higher for HRA (€2,918.90 vs. €1,985.23; q < 0.0001), whereas operating-room personnel costs were higher for UKA (€371.59 vs. €335.45; q = 0.0035). Costs incurred outside the operating room and non-medical costs did not differ significantly. Implant costs were higher for HRA (€2,544.55 vs. €1,554.55; q < 0.0001). After FDR adjustment, length of stay was associated with laboratory and imaging costs in the UKA group and with laboratory costs in the HRA group.

Conclusion: UKA and HRA showed distinct patterns of index-hospitalization costs and resource utilization. Higher implant expenditure was an important component of the observed cost difference. These findings represent a hospital-level comparison of two distinct arthroplasty pathways and should not be interpreted as evidence favoring either procedure. Detailed evaluation of procedure-specific cost structures may support hospital budgeting, resource allocation, implant procurement, and operational planning.