Differences in the radiological characteristics between post-traumatic and non-traumatic knee osteoarthritis.

Osteoarthritis (OA) of the knee can be defined as primary (non-traumatic) or secondary (post-traumatic). Both non-traumatic OA and post-traumatic OA have been described predominantly in the medial compartment of the knee. The objective of this study was to compare the location of structural radiographic changes in non-traumatic OA and post-traumatic OA. A non-traumatic cohort, consisting of 155 patients suffering from chronic knee pain without known major injuries, was compared with a post-traumatic cohort, consisting of 176 patients, all of whom had sustained an anterior cruciate ligament injury while playing soccer. A standardized weight-bearing knee radiography of the tibiofemoral joint was performed. Joint space narrowing (JSN) and osteophytes were graded according to the radiographic atlas of the Osteoarthritis Research Society International. JSN and osteophytes were located predominantly in the medial compartment in the non-traumatic cohort. In the post-traumatic cohort, structural changes were evenly distributed between the lateral and the medial compartments. We were thus able to demonstrate radiological differences between post-traumatic and non-traumatic OA.