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

INTRODUCTION: 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. MATERIALS AND 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 Eq. 5D 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.