Ten- to 14-Year Results of a High-Flex Rotating Platform Knee Implant: A Follow-Up Report of a Prospective Cohort.

Abstract

High-flex posterior stabilised rotating platform (PSRP) implant was introduced to provide for deep knee flexion. Few short-term results have been reported, but there are no long-term outcomes reported. We prospectively followed 48 patients (53 knees) implanted with one such design. Inclusion criteria for implantation were patients with good pre-operative flexion and wishing to perform activities requiring deep knee flexion post-operatively, with femorotibial varus angle < 15° and having good flexion stability at trialling stage. Previously, we reported their outcomes at 2-6years (FU-1). We now report their functional and radiological results at a minimum follow-up of 10years (FU-2) in 39 patients (43 knees); 5 patients having died and 4 lost to follow-up. The mean pre-operative flexion of 124° improved to 130° at FU-1 and to 134° at FU-2. Flexion of 130° or more was seen in 59.6% knees at FU-1 and 74.42% knees at FU-2. At FU-2 mean Knee score was 90.5 and Function score was 67.8. Incidence of patellofemoral symptoms increased from 7.7% at FU-1 to 11.36% at FU-2. There were no cases of bearing spin out, osteolysis or revision surgeries. At a minimum 10-year follow-up, high-flexion PSRP design in selected patients yielded 100% survival. We recorded good knee flexion and knee society scores, with no case of spin out, implant loosening, osteolysis or revision surgery. Although deep knee flexion improved at longer follow-up, its use in ADL had reduced due to other age-related factors. There was increased incidence of patellofemoral symptoms.