Background: This investigation sought to quantify incidence rates (IRs) and risk factors for primary and secondary (ie, posttraumatic) osteoarthritis (OA) of the knee in an active military population.
Methods: We performed a retrospective review of United States military active duty servicemembers with first-time diagnosis of primary (International Classification of Disease, 9th Edition code: 715.16) and secondary (International Classification of Disease, 9th Edition code: 715.