COMPARISON OF OUTCOMES IN SIMULTANEOUS, STAGED AND UNILATERAL TOTAL KNEE REPLACEMENT

Abstract

Introduction The decision to perform bilateral total knee replacement (TKR) either simultaneously or as a staged procedure is made depending on the level of disease severity, comorbidities, total anaesthetic time and cost. We compared the outcomes of these two bilateral groups of patients with unilateral TKR.

Methods Between August 1992 and December 2002 all patients requiring primary TKR received an uncemented, hydroxyapatite-coated, posterior cruciate ligament retaining prosthesis implanted by the senior author. All peri-operative complications were recorded prospectively, as were pre-operative and post-operative knee scores (Knee Society Clinical Rating Score) at three and six months, and one, two, five, and 10 years thereafter. Patients were divided into three groups being; simultaneous bilateral TKR (SIM), staged bilateral TKR (STA), and unilateral TKR (SIN) with the outcomes of each group compared for statistical significance. One thousand one hundred and forty patients (1638 knees) were included in the study. The majority of patients were female in the STA and SIN groups (60% and 53% respectively) and males in the SIM group (57%). There were 790 (SIM), 206 (STA), and 642 (SIN) knees with mean ages of 67 (SIM), 65 (STA), and 67 years (SIN). The primary diagnosis was OA in each of the groups (> 93%).

Results Pre-operative and post-operative scores revealed no significant differences (p> .05) between the groups. Mean scores ranged from 94 to 98 pre-operatively and increased up to 182 to 187 at five years. Post-operative complications were significantly higher (p< .01) in both bilateral groups. There were 68 (17.2%) and 16 (15.5%) cases of thrombi in the SIM and STA groups respectively compared to 60 (9.3%) cases in the SIN group. Pulmonary emboli were also significantly higher in the bilateral groups compared to the unilateral group (p< .01). The rate of deep infection was higher (p=.09) in the STA group compared to the SIM and SIN groups (2.9% of patients compared to 1.1% and 1.4% respectively). There have been 10 revisions (four SIM, one STA, and five SIN) and two cases of peri-operative death (one STA, one SIM) both due to MI.

Conclusions While simultaneous TKR has higher rates of post-operative complication compared to unilateral TKR, it is less than staged TKR. Therefore simultaneous bilateral knee replacements, when indicated, are the ideal treatment of choice compared to staged procedures.