Volume changes in the menisci and articular cartilage of runners: an in vivo investigation based on 3-D magnetic resonance imaging.

BACKGROUND: Articular cartilage contributes to transferring enormous loads as uniformly as possible from one skeletal segment to the next. Whether it manages this task when subjected to the high repetitive loading cycles occurring during long-distance running and can remain intact is still the topic of controversy.
PURPOSE: To investigate the changes in cartilaginous volumes of the tibia, patella, and medial and lateral menisci after extreme dynamic loading as occurs in long-distance runners. STUDY
DESIGN: Controlled laboratory study.
METHODS: Forty-eight knees of male athletes were studied (38 +/- 14 years). The subjects ran around a predetermined and precisely measured course (5, 10, 20 km), the beginning and end of the run being in the magnetic resonance imaging investigation room. The scan protocol was 60-minute rest period, first measurement, run, 3-minute delay, and second measurement.
RESULTS: Overall, there were significant reductions in volume (P < .05) for the patella, tibia, and menisci. There was evidence of significant change after a running distance of 5 km. A further statistical reduction of the volume could only be demonstrated for the medial meniscus after 10 and 20 km.
CONCLUSION: Tibial, patellar, and meniscal cartilaginous volumes show not only load-dependent volume changes but also an asymptotic curve. This is the first time that meniscal volume changes due to loading have been used as an indicator of the important mechanical contribution that the menisci make to sustaining the knee during repetitive loading. CLINICAL RELEVANCE: On the basis of the results of this study, the authors assume that the cartilage is able to adapt well to the loads caused by running.