Unit Sales Trends of Hip Arthroplasty Procedures Performed in Ontario in 2020.

BACKGROUND: In March 2020, an emergency was declared in the province of Ontario owing to the COVID-19 pandemic. From March 19 to May 26, all elective total hip arthroplasty (THA) and total knee arthroplasty (TKA) procedures were deferred. The purpose of this study was to review the unit sales data of THA and TKA procedures in Ontario over this time period to identify any trends in surgical activity. METHODS: Unit sales data for all THA and TKA procedures performed in Ontario between January 2019 and December 2020 were reviewed. All orthopedic companies contributed to the data set. Femoral stems were considered an indicator of THA procedures, while primary femurs were considered an indicator of TKA procedures. Data were analyzed to determine trends in THA and TKA procedures during the deferral period and the relative change in THA and TKA activity following resumption. RESULTS: There was a 53% reduction in THA activity between March and May of 2020 when compared to the same interval in 2019. From June to September of 2019, THA sales activity was 87.3% that of TKA. From June to September of 2020, THA sales activity was 122.8% that of TKA. CONCLUSION: Provincial directives aimed at controlling the outbreak of COVID-19 contributed to a substantial reduction in THA and TKA activity in 2020. Compared to 2019, there was a disproportionate increase in THA compared to TKA activity in 2020 following resumption of surgical services. These data have implications in recovery planning for the surgical backlog of THA in Ontario.

Pseudotumors and High-Grade Aseptic Lymphocyte-Dominated Vasculitis-Associated Lesions Around Total Knee Replacements Identified at Aseptic Revision Surgery: Findings of a Large-Scale Histologic Review.

BACKGROUND: Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) development (including pseudotumors) secondary to metal debris generation around total hip arthroplasties is a well-recognized histopathologic phenomenon. Emerging data have highlighted a similar potential concern around TKAs although the body-of-knowledge has largely been limited to individual case reports or small retrospective case series. This study sought to establish the prevalence of pseudotumors or high-grade ALVALs seen at the revision of primary TKAs and to establish the correlation between histologic ALVAL grade and patient-reported functional outcome measures. METHODS: The findings of 321 non-infective (aseptic) patients undergoing unilateral revision knee surgery, at a high-volume tertiary referral center, were reviewed. Each case was independently histologically classified. Complete patient-reported functional outcome measures were available for 134 patients (42%) allowing correlation between functional performance and histopathology results. RESULTS: Five distinct pseudotumors and a further 18 high-grade ALVALs were histologically identified representing 1.6% and 5.6% of the cohort, respectively. When compared by histologic grade, Oxford Knee Score and Western Ontario and McMaster University's Osteoarthritis Index suggested a high correlation between ALVAL grade and functional knee scores. CONCLUSION: These findings suggest a prevalence of pseudotumors or high-grade ALVALs at revision TKA surgery of >7%. This unexpectedly high result may contribute insight into the previously under-appreciated significance of metal debris-related local tissue reactions around TKAs. The findings also demonstrate a strong near-linear inverse relationship between patient-reported clinical knee performance and the underlying histologic grade of local tissue reaction. These results have potential management implications for patients with underperforming TKAs and should prompt consideration of an ALVAL secondary to metallosis in the differential diagnosis. LEVEL OF EVIDENCE: This is a retrospective cohort study with Level III evidence.