Iraqi Postgraduate Medical Journal

Abstract

ABSTRACT:
BACKGROUND:
To prevent posterior subluxation of the tibia and to improve range of motion and stair climbing ability, total knee prosthesis was modified to the posterior stabilized (PS) one in 1978 and further modifications followed. The Knee Society in 1989 introduced a rating score for TKA named the Knee Society Score (KSS), it's widely used and revised in 2012.
OBJECTIVE:
To study the clinical and radiological results of PS/ TKA.
PATIENT AND METHOD:
We prospectively studied 30 patients with PS/TKA. The mean age was 63 years and mean follow-up was 12 months, 24 knees had osteoarthritis (OA) and 6 knees were rheumatoid (RA). All were unstable and malaligned. The results assessed using the scoring system of Insall et al. and the KSS. Postoperative radiological assessment performed using weight-bearing AP and supine lateral radiographs.
RESULTS:
At last visit, 9 knees (30%) had excellent result, 18 (60%) had good result and 3 (10%) had fair result. The mean KSS improvement was from 31 points preoperatively to 89 points postoperatively. The mean ROM (flexion) preoperatively was 68.5o improved postoperatively to 106o. Postoperatively all knees were stable in AP direction only 4 (13.3%) had mild lateral instability. The ideal position for femoral component within (6-10o) valgus was obtained in 24 knees (80%), it was within (0-5o) valgus in 6 knees (20%). In 93% (28 knees) the tibial component were within 2o of varus or valgus, 6.6% (2 knees) was in greater than 2o varus. Knee function score improved from a mean 27.5 points preoperatively to 58 points postoperatively and patients were able to walk more than 500 meters.
CONCLUSION:
PS/TKA increases range of motion, increases joint stability and improved gait. Both OA and RA patients responded well to its use with nearly same end results. We strongly recommend the use of PS/TKA for primary total knee replacement.