Effect of Modified Frailty Index on Postoperative Outcomes after Total Knee Arthroplasty

Objective: To determine the impact of the modified frailty index (MFI) on patient-reported outcome measures (PROMs) using the knee injury and osteoarthritis outcome score (KOOS-12) following total knee arthroplasty (TKA). Study Design: Prospective-observational study. Place and Duration of the Study: Department of Surgery, Section of Orthopaedics, The Aga Khan University Hospital, Karachi, Pakistan, from August 2023 to July 2024. Methodology: Sixty-six patients undergoing primary TKA were included, while those undergoing revision surgery were excluded. Each patient’s frailty score was noted using the MFI. The primary outcome, KOOS-12 was collected preoperatively and at six weeks, three months, and six months postoperatively. Repeated measures ANOVA assessed the association of MFI and time on KOOS-12 scores. Results: Patients with severe frailty levels showed significantly lower KOOS-12 scores at each time point, indicating low-grade improvement in outcomes in pain, function, and quality of life domains as compared to fit individuals. Severely frail patients had a mean KOOS-12 score of 26.3 ± 14.4 at admission, which improved to 65.5 ± 17.7 at six months, while non-frail patients showed higher baseline and follow-up scores. Repeated measures ANOVA results revealed significant effects of MFI level and time on KOOS-12 scores (p <0.001), with significant improvement across all domains over time. Conclusion: High frailty is associated with overall lower KOOS-12 score as compared to individuals with no frailty after TKA. These findings emphasise the value of frailty assessment in predicting functional outcomes and guiding preoperative counselling and postoperative rehabilitation to optimise recovery for frail patients undergoing TKA.