Posttraumatic Arthritis Is More Common in Patients Undergoing Total Knee Arthroplasty Before Age 50.

Primary total knee arthroplasty (TKA) in patients under 50 is becoming more common. The goal of this study was to identify the diagnoses and predisposing factors for TKA prior to age 50. The Military Data Repository was queried for patients undergoing TKA prior to age 50. The cohort was matched to older patients. A total of 1,504 patients underwent manual record review for demographics, prior knee surgery, and indication for TKA. Primary osteoarthritis was the most common indication in both cohorts. Posttraumatic osteoarthritis was more common in patients who underwent TKA before age 50 (28%) compared with patients 50 and older (7%; p < 0.001). Patients who underwent TKA before age 50 were more likely to have previous anterior cruciate ligament injury, or any previous ipsilateral knee surgery (p < 0.001). These data suggest an association between prior knee injury and age at time of TKA. (Journal of Surgical Orthopaedic Advances 33(2):072-076, 2024).