Higher risk of revision for partial knee replacements in low absolute volume hospitals: data from 18,134 partial knee replacements in the Dutch Arthroplasty Register

Abstract

Background and purpose — Partial knee replacement (PKR) survival rates vary a great deal among registries and cohort studies. These discrepancies can largely be attributed to inappropriate indications of the PKR and low thresholds for revision, but also to the PKR volume. This study used Dutch Arthroplasty Register data to analyze whether absolute PKR or proportional PKR hospital volume is associated with the risk of revision. Patients and methods — 18,134 PKRs were identified in the Dutch Arthroplasty Register from 2007 to 2016. For each year, hospitals were divided into 4 groups based on the quartiles for the absolute volume (< 22, 22–36, 36–58 and > 58 PKRs per year) and the proportional volume (< 8.5, 8.6–14.2, 14.3–25.8 and > 25.8% PKRs). Kaplan–Meier survival analysis was performed to determine survival rates. A multivariable Cox regression adjusted for age category, sex, ASA score, year of surgery, diagnosis, unicondylar side, and type of hospital was used to estimate hazard ratios (HR) for revision. Results and interpretation — Proportional PKR volume did not, but absolute PKR volume did influence the risk of revision. The adjusted HR for hospitals with an absolute volume of 22–36 PKRs per year was 1.04 (95% CI 0.91–1.20), 0.96 (CI 0.83–1.10) for the hospitals with 36–58 PKRs, and 0.74 (CI 0.62–0.89) for hospitals with more than 58 PKRs compared with hospitals that had fewer than 22 PKRs per year. So, patients treated with a PKR in a high absolute volume hospital have a lower risk of revision compared with those treated in a low absolute volume hospital.

Reduced 5-Year Risk for Revision of the Oxford UKA Using New Instrumentation versus Conventional Instrumentation: A Registry Study of 12,867 UKAs

“…Studies have shown that these are related to UKA survival. 7,29 Furthermore, there is a notable difference in the usage of cemented and cementless implants between the new and conventional instrumented UKAs, which could possibly bias the revision risk (as cemented implants are associated with a higher revision risk). 30 However, no multicollinearity was found between instrumentation type and fixation type (variance inflation factor <2.5), and with 14% of cementless implants in the conventional instrumented UKAs, our multivariable Cox regression model was expected to adequately adjust for this confounder.…”

“…However, we could not adjust for hospital or surgeon related factors, such as experience and exposure. Studies have shown that these are related to UKA survival [7,29]. Furthermore, there is a notable difference in usage of cemented and cementless implant between the new and conventional instrumented UKA's, which could possibly bias the revision risk (as cemented implant are associated with a higher revision risk) [30].…”

“…Time acts as a confounder because of the development of surgical techniques and implants. Moreover, there is an increasing use of UKAs among surgeons, which results in more experienced surgeons with probably improving UKAs outcomes [7,29]. Since the majority of UKAs using the conventional instrumentation is performed before and UKAs using the new instrumentation after 2012, we could not match the…”

Nationwide partial knee replacement uptake is influenced by volume and supplier––A Dutch arthroplasty register study

“…The effect of KA volume and the availability of a frequently used PKR on the actual PKR use described in this study has not been reported earlier. Many studies report on the effect of PKR volume on outcome, especially with regard to the survival, 7,9,10,18,19 but never on the effect of volume on the actual use and certainly not in combination with the supplier. Previous studies showed a better survival in hospitals with a higher absolute or proportional PKR volume.…”

“…This will lead to an increase in number of hospitals using PKR but not necessary to more PKR usage within the hospital, which is needed to achieve optimal PKR results. 7–10,18 This demands an intrinsic motivation by the surgeon and the hospital to adopt the complete PKR philosophy with applying the strict inclusion criteria for this procedure and achieving sufficient volume. The discrepancy of an even stronger increase in PKR use in larger volume hospitals with a supplier without a frequently used PKR implant in their product range as found in this study, may especially reflect this intrinsic motivation.…”