[Unicompartmental PCA series]

Between 1985 and 1988, 110 PCA unicompartmental knee arthroplasties were performed by the same surgeon. At review in 1993, after at least 5 years follow-up, 11 patients were dead, 90 patients were seen, examined and X-rayed; 5 patients replied by filling in a questionnaire and 3 had not been seen for a year. There were 73 women (74.4%) and 25 men; mean age was 68.6, mean height was 162.5 cm and mean weight 70 kg. Only 13 showed signs of obesity (BMI>30). 74 medial prostheses were placed for correction of genu varum (mean deviation: 8.5°) and 24 lateral prostheses were placed for correction of genu valgum (mean deviation: 13.5°).90 prostheses were cementless (92%). There was no release, no surgery was performed on the patella or the lateral compartment.Early postoperative complications were rare: 1 early infection, 15% of thrombo-phlebitic complications without pulmonary embolism, no early dislocation.Results at more than five years were evaluated using Hungerford's score which rose from 48 to 81.5 postoperatively. We noted 72.4% of good and excellent results (43 excellent, 28 good) and 10.2% of poor results. Mean flexion was 111.5° (>120° in 72% of patients). Mean pain was evaluated at 42 (maximum score: 50) and 54% of patients had an unlimited gait perimeter.Secondary and late complications: - inexplicable pain: 10 out of 98 patients, - 1 tibial loosening; no reoperation performed, - 2 antero-posterior laxities, 1 painful, - no pathological stiffness.Reoperations: 18 patients were reoperated: - 1 by arthroscopy and division of the lateral process because of inexplicable medial pains (followed by no improvement), - 1 arthrodesis because of septic complications, - 16 patients were reoperated and converted to total knee prosthesis: 3 because of inexplicable pain (followed by no improvement); 3 because of dislocation of the femoral prosthetic condyle; 1 inexplicable and 9 because of femoral loosening or mobility of the femoral prosthetic condyle.Our series of PCA unicompartmental arthroplasties yielded nearly 73% of good and excellent results at more than five years' follow-up, although the prostheses were fitted without cement in 9 out of 10. Contrary to the usual belief, the weak spot is not the tibial plateau but the femoral prosthetic condyle whose design is inadequate and responsible for most of the complications observed.