OA AND RUNNING

marised the impact history of the athletes’ previous training ses- sions. All runners whether beginners, recreational athletes or pro- fessional runners had normal pre-marathon MRI images. In the beginner group, joint effusions were seen in 70% of the athletes whereas recreational and professional runners demonstrated no abnormalities. The conclusions of this study were that long dis- tance running can potentially cause overuse reactions in athletes not accustomed to high impact loading. Whether recreational and professional runners represent a selected group - the weak stay behind - or whether regular physical activity results in adaptation to impact loading can not be said.

In a further study (7), we assessed articular cartilage volume changes in the knee joint after a 20 km run using a modified MRI protocol. The reduction in cartilage volume averaged 8% in the patella, 10% in the menisci and 6% in the tibial plateau. There was a significant increase in cartilage volume 60 minutes after the run to nearly normal values. Using a more sophisticated tech- nique, we could demonstrate that articular cartilage volume decreases with running-associated loading but recovers quickly following the cessation of running. The most likely explanation is the expression of water from the cartilage due to the constant impact. The speed with which the volume returns to near normal is impressive and a clear indicator for the extracellular matrix being intact. Schueller-Weidekamp evaluated knees of runners using MRI and concluded that only subtle changes such as joint effusions or increased signal alterations were seen on the post run MRI image. The study did not, however, mention the athletes’ experience and training volume. The encouraging finding of this study is that pre-existing lesions within the cartilage and menis- cus were not exacerbated.

Krampla (8) used MRI to assess medium-term effects of long dis- tance running and demonstrated that eight weeks following com- petition, the mensical alterations and bone marrow changes seen in 25% of subjects disappeared. Shellock (9) examined the knees of trained runners and could not demonstrate any structural changes after competition. Kersting (10) used biochemical mark- ers (serum cartilage oligometric matrix protein - (COMP) to exam- ine the relationships between mechanical loading, cartilage vol- ume and protein excretion measured by serum COMP levels. Blood samples and MR images were taken prior to and following 1 hour training runs. They found a positive correlation between COMP

serum levels and cartilage volume alterations. While this study is a welcome attempt to assess the reduction of cartilage volume and the relation to serum expression of COMP, a standard MR image can not measure volume changes of cartilage. Bias has thus been introduced. Nevertheless, the increase of COMP levels after one hour of running seems to indicate that more than fluid shifts are to be expected and suggests that some damage to the extra- cellular matrix occurs when exposing lower extremity joints to continual impact. MRI is currently the most sensitive method to investigate articular cartilage and soft tissue. Sensitivity, speci- ficity, reliability and validity of this instrument has been demon- strated by multiple authors. In concluding this section, what can be derived from the radiological studies mentioned above? Either the measuring tool is not good enough to detect changes or that indeed the human body is able to compensate for all the imposed stress. It is of importance to mention that all those studies used healthy subjects with no evidence of degenerative joint disease. As a consequence, conclusions can not be drawn for joints where degeneration is evident already.

CLINICAL EVIDENCE Kujala (11) assessed the relative risk of osteoarthritis in former elite athletes and compared them to a control group. He conclud- ed that all athletes who were involved at high level competitive sports had a higher incidence of premature arthritis. Odds ratios for arthritic changes were calculated as 1.73 for endurance ath- letes and 2.17 for power athletes. Spector (12) found a signifi- cantly higher rate of osteoarthritis in former mid- and long-dis- tance female runners. Within the control group, females with a history of long-term vigorous weight-bearing exercise had similar rates. Drawer (13) investigated former professional soccer players. His results indicated that the risk for professional soccer players of osteoarthritis in at least one of the lower extremity joints is very high and significantly greater than for the general popula- tion. The results support the suggestion that professional soccer players should be provided with regular health checks during their playing career. Marti (14) assessed former elite long-distance run- ners. He demonstrated that age and mileage emerged as positive predictors of radiological signs of degenerative hip disease. Sarna (15) looked at overall health in former elite athletes and found that they have a slightly higher risk for lower limb osteoarthritis. Deacon (16) looked at Australian rules footballers and demon- strated a significantly higher risk of osteoarthritis.

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