Short-term Clinical and Radiologic Outcomes, and Survivorship Following Primary Total Knee Arthroplasty Using a Novel High-Flexion System among Indian Patients.

INTRODUCTION: High-flexion total knee arthroplasty (TKA) prostheses permit deep knee flexion, which is important for day-to-day activities, especially among Indian patients. However, some high-flexion designs have been reported to be associated with early aseptic loosening and valgus instability in the past. Close monitoring of patients undergoing TKA using newer high-flexion prosthetic designs is imperative. The purpose of this study was to evaluate the short-term clinical outcomes and prosthetic survivorship of Indian patients following TKA using the Zenith® high-flexion system.

MATERIALS AND METHODS: Overall, 101 patients who underwent TKA using the Zenith® high-flexion system for osteoarthritis of the knee between June 2022 and August 2023 across four tertiary care hospitals were studied. Their pre-operative and post-operative knee range of movement and clinical evaluation scores were assessed. In addition, short-term prosthetic survivorship was assessed. Adverse events, if any, were recorded.

RESULTS: The study cohort included 51 men and 50 women with a mean age of 62.37 ± 6.96 years. Cruciate-retaining and posterior-stabilized prostheses were used in 58 and 43 patients, respectively. All patients were followed up for a minimum of 2 years postoperatively. Post-traumatic valgus instability necessitating revision TKA occurred in one patient; data pertaining to this patient were used for survivorship analysis, but not for evaluation of clinical outcome scores. Mild anterior notching occurred in one patient. No other adverse events were recorded. Knee flexion improved significantly from 97.82° ± 12.11° preoperatively to 114.11° ± 7.26° postoperatively (P < 0.001). Significant improvements in the Knee Society Knee Score (40.81 ± 15.18 preoperatively, to 88.58 ± 8.41 postoperatively) (P < 0.001) and Knee Society Functional Score (59.56 ± 16.43 preoperatively, to 95.69 ± 6.60 postoperatively) (P < 0.001) were noted. The mean Forgotten Joint Score at 2 years' follow-up was 87.64 ± 15.57. When revision for all causes was considered, the 2-year prosthetic survivorship as evaluated using a Kaplan-Meier plot was 99%.

CONCLUSION: The Zenith® high-flexion system is associated with satisfactory short-term clinical outcomes and prosthetic survivorship. Further research is required to evaluate its performance in the mid- and long-term.