Comparative outcomes of total knee arthroplasty in patients with posttraumatic versus primary knee osteoarthritis

Background Posttraumatic osteoarthritis (ptOA) of the knee accounts for 12.5% of all total knee arthroplasties (TKA) and is associated with significantly higher complication and revision rates than in TKA for primary osteoarthritis (pOA). However, the impact of ptOA on patient-reported outcomes is less clear. The purpose of this study is to analyse longitudinal clinical and patient-reported outcomes in these patient groups. Methods A retrospective analysis of prospectively collected data from an institutional database was performed (time frame 2006–2023). Patients with a history of intraarticular femoral or tibial fractures (ptOA) were identified, and propensity score matched (1:3 ratio) for age, sex and body mass index (BMI) to a comparable cohort receiving TKA for pOA. Outcomes at one year were assessed using the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), Forgotten Joint Score-12 (FJS-12), EuroQo-5D (EQ-5D), range of motion (ROM) and overall patient satisfaction. Results 72 patients with ptOA were compared to 216 matched pOA patients. There were no statistically significant differences in WOMAC (19.95 vs 15.61; p = 0.15) or EQ-5D (0.75 vs 0.80; p = 0.14) between the two groups at 1-year follow-up. FJS-12 showed significantly inferior result 1-year postoperatively in the ptOA group (56.4 vs 71.3; p = 0.02). Overall patient satisfaction (72.4 vs 89.6%; p = 0.001) and pre- and post-operative ROM (p < 0.001) were also significantly worse in the ptOA group. Conclusions There was no difference in traditional joint-specific or general heatlh scores (WOMAC or EQ5D scores) between patients with primary or posttraumatic OA. However, patients undergoing TKA for ptOA reported poorer higher-level outcomes (FJS-12 scores), poorer satisfaction rates and poorer knee flexion at 1-year. Trial Registration: Ethics committee of Eastern Switzerland EKOS; Project-ID 2023 − 00813, Registration date 03.05.2023