Post-Traumatic Arthritis: Definitions

Osteoarthritis is the most common form of arthritis. It accounts for more mobility disability than any other disease and is one of the leading causes of disability in the USA and worldwide [1]. Data from the National Arthritis Data Workgroup in the USA suggests that roughly 6 % of adults aged 30 and over have symptomatic OA of the knee and of those aged 60 and over, the prevalence rises to 12 % [2]. The prevalence of symptomatic hip OA is approximately half that of knee OA. The prevalence of knee OA in the UK is roughly similar to estimates in the USA [3]. Ankle OA, while often uniquely post-traumatic, is much less prevalent [4] than arthritis in the knee or hip. Roughly 7 % of older persons have symptomatic hand OA [5] and based on population surveys, hand OA more often has effects on pain and function than commonly acknowledged. These prevalence estimates are based on counting persons with a positive X-ray for OA and joint pain in the affected joint as having disease. Since it has become clear that radiographic changes of OA occur late in disease and many persons without X-ray OA may have joint pain with MRIs showing OA [6], the prevalence of OA is likely to be even higher than current prevalence estimates suggest. The prevalence of knee OA in China appears to be at least as high as in the USA [7] but, like the USA, most of it is not associated with major prior joint injury. However, the high rates of knee OA in rural communities including in China suggest that joint injury, either acute or chronic, plays a major etiologic role in knee OA. Knee OA prevalence is rising in the USA and there is a commensurate rise in the rates of knee replacement. While most of this increase in prevalence may be due to aging and increased ponderosity of the US population, other factors are also at play. For one, given the same severity of radiographic knee OA, persons currently seem to be more inclined to complain of knee pain and OA symptoms than their predecessors [8]. Major joint injury causes a large percentage of OA of the knee in the community and causes the majority of cases of OA in joints that are otherwise rarely affected by disease including ankle, wrist, and elbow. Also, post-traumatic knee OA secondary to sports-related injuries may be increasing. J.A. Buckwalter, M.D., M.S. (*) Department of Orthopedics and Rehabilitation, University of Iowa Hospitals, 200 Hawkins Drive, Iowa City, IA 52242, USA