[Results of single stage vs. two-stage total knee arthroplasty]

The total knee arthroplasty (TKA) is a successful procedure. In cases of bilateral knee osteoarthritis, advantages of single stage TKA vs. two-stage TKA as well as the gap between the procedures in case of two-stage TKA are discussed controversially. The aim of the present study is to compare the clinical and radiographic results of single stage bilateral TKA and two-stage bilateral TKA. In cases of two-stage TKA the dependency on the gap between surgeries was determined.

In this retrospective study 43 patients with single stage TKA and 35 patients after two-stage TKA with a maximum of 12 months between surgeries were included. Follow-up was in mean 31 ± 15 months. For clinical and radiological evaluation the Knee Society score (KSS) and Stolzalpen knee score were used. Quality of life was measured by the SF-36 score. The pain was determined using a visual analogue scale (VAS). Radiological evaluation was done by use of Knee Society roentgenographic evaluation and scoring system.

The overall hospital stay for patients with two-stage TKA (26 ± 5 days) was twice as long as for patients with single stage TKA (14 ± 4 days). Patients with single stage bilateral TKA had a significantly higher KSS level (186 ± 19 points) than patients after two-stage bilateral TKA (179 ± 22 points). Within the two-stage group the best range of motion was achieved by patients with a gap of 4 to 6 months between surgeries and a decreased point value was measured in patients with a gap of 10 to 12 months between TKAs. Using the VAS patients with simultaneous bilateral TKA had significantly increased pain levels during passive motion. Within the two-stage group there were no differences in VAS. The results of Stolzalpen knee score were comparable in both groups. The analysis of radiological measurements showed a significantly higher number of radiolucent lines (1 mm) in patients with single stage TKA without any clinical relevance or progress in follow-up. Patients with single stage bilateral TKA had a higher complication rate than patients with a two-stage procedure. In the single stage group 6 patients had to be revised because of fracture, dislocation, peroneal nerve palsy, patella lateralisation or loosening. In the two-stage group only one patient had to be revised due to a quadriceps tendon rupture caused by a fall at day one after surgery.

Analysis of clinical and radiological results shows only marginal differences between the two groups. In two-stage procedures functional results were best when the second surgery was done 4 to 6 months after the first procedure. Single stage TKA had a significantly higher complication rate. However, patient and surgeon should make the decision for single or two-stage bilateral TKA individually.