Hospital Volume and Outcomes in Total Knee Arthroplasty

Medical research is increasingly examining the volume-outcome relationship in total knee arthroplasty (TKA), exploring whether the number of procedures a hospital performs correlates with better patient results. A recent study published in Nature focused on non-linear volume-outcome relationships using a sample of more than 60,000 hospital cases from Germany between 2020, and 2023.

The concept of a volume-outcome relationship suggests that hospitals or surgeons who perform a higher volume of a specific procedure may achieve better outcomes due to increased experience, standardized processes, and specialized infrastructure.

Evidence from Systematic Reviews

A systematic review and dose-response meta-analysis published on September 8, 2021, in Knee Surgery, Sports Traumatology, Arthroscopy, analyzed 68 cohort studies with data spanning from 1985 to 2018 to investigate these links.

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The meta-analysis found that higher hospital volume is likely associated with lower mortality rates within three months following the procedure. Specifically, the research indicated an odds ratio (OR) of 0.91 per additional 50 TKAs performed per year.

The same review indicated that higher volume is likely associated with lower readmission rates within three months, reporting an OR of 0.98 per additional 50 TKAs per year.

the narrative synthesis of seven studies involving 301,378 patients suggested that higher hospital volume may be associated with a lower rate of early revision within 12 months.

Variable Outcomes and Limitations

Despite the associations with mortality and readmissions, the research highlighted that hospital volume may not be associated with all TKA outcomes. The findings suggested no clear link between hospital volume and the rates of deep infections within one to four years, late revisions between one and 10 years, or adverse events within three months.

The confidence in the cumulative evidence varied significantly across different metrics. The 2021 meta-analysis reported moderate confidence for mortality and readmission rates, low confidence for early revision rates, and very low confidence for deep infection, late revision, and adverse event rates.

The risk of bias for all outcomes in that specific meta-analysis ranged from moderate to critical.

Institutional vs. Individual Volume

While hospital-wide volume is a primary focus of these studies, other research has looked at the role of the individual surgeon within a high-volume setting. A study from the Hospital for Special Surgery (HSS), a high-volume academic orthopedic center, found that infection rates after total knee arthroplasty remained low regardless of the individual surgeon’s volume.

This suggests that the institutional environment and systemic protocols of a high-volume center may play a significant role in maintaining low infection rates, independent of the specific number of surgeries performed by an individual practitioner.

Clinical Implications and Regulation

The ongoing investigation into these relationships, including the use of regression splines to identify non-linear trends in German hospital data, informs discussions regarding minimum volume regulation. Such regulations aim to ensure that procedures are performed in settings that meet a specific threshold of experience to optimize patient safety.

The conclusion of the systematic review is that an inverse volume-outcome relationship probably exists for some TKA outcomes, most notably mortality and readmissions, and may exist for early revisions.