Date of Award

January 2012

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Keggi K. Kristaps

Subject Area(s)

Medicine, Surgery

Abstract

There is scant literature directly comparing the outcomes of unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). The purpose of this study was three fold: 1) to determine factors predictive of requiring an allogeneic blood transfusion following TKA, 2) to compare total blood loss between UKA and TKA, and 3) to compare clinical and functional outcomes between patients that underwent UKA and TKA through the Short Form 12 (SF-12) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) surveys. To determine factors predictive of allogeneic blood transfusion following TKA, I retrospectively evaluated 644 primary unilateral TKAs without autologous blood predonation at Columbia University's Center for Hip and Knee Replacement. Thirty-one independent variables were analyzed via multivariate logistic regression to determine associations with the endpoint of allogeneic transfusion. To compare blood loss between UKA and TKA, I retrospectively reviewed the charts of 99 patients that underwent unilateral UKA and 99 patients that underwent unilateral primary TKA that were matched for age, gender, and body mass index. Total blood loss was calculated on the basis of estimated blood volume and the change in hematocrit concentration between pre-operative and post-operative levels. To compare clinical and functional outcomes between patients that underwent UKA and TKA, I prospectively collected data on 128 TKAs and 70 UKAs. Baseline SF-12 Physical Component, SF-12 Mental Component, WOMAC Pain, WOMAC Stiffness, and WOMAC Physical Function scores were recorded. Post-operatively, SF-12 and WOMAC clinical outcome measures were recorded during annual follow-up visits. Of the 644 TKAs analyzed, 71 (11.0%) received an allogeneic transfusion. Multivariate logistic regression analysis demonstrated a significant relationship between transfusion and age, anemia, pre-operative hemoglobin level, and surgical time. Peri-operative blood loss during UKA (405mL) was significantly less than peri-operative blood loss during TKA (725mL). Multivariate analysis demonstrated higher SF-12 and WOMAC scores for UKA patients while controlling for pre-operative variables. Crude and adjusted differences in SF-12 Physical Component, SF-12 Mental Component, WOMAC Pain, and WOMAC Physical Function surpassed the threshold for minimal clinically important difference. Furthermore, UKA patients had larger improvements in SF-12 Physical Component, SF-12 Mental Component, WOMAC Pain, and WOMAC Physical Function scores from baseline than TKA patients. UKA is associated with less blood loss and leads to a greater increase in mental well-being, relief of pain, and improvement in physical function than TKA. UKA should be the primary treatment option for isolated unicompartmental osteoarthritis of the knee. Furthermore, in patients with isolated unicompartmental knee arthritis that are of advanced age, have comorbid anemia, and have decreased pre-operative hemoglobin levels, TKA should be avoided in light of the increased risk for transfusion.

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