In vivo cartilage deformation after different types of activity and its dependence on physical training status

Eckstein F, et al. · Annals of the Rheumatic Diseases

Patellar cartilage lost 2.8% of its volume after walking, 4.5% after cycling, 5.0% after running and 5.9% after 30 knee bends, the magnitude tracking the range of knee motion the activity used. Femorotibial cartilage barely moved: nothing significant in either femoral condyle after any activity, and tibial deformation reached 6.1-7.2% only after drop jumps. Patellar deformation after knee bends was the same in weight lifters, sprinters and untrained men (2.9%, 3.9% and 4.1%, ns), which the authors read as no evidence that adult cartilage properties adapt to training in a way this method can detect.

Population

Healthy volunteers in three samples: 12 for patellar deformation across activities, 10 for femorotibial deformation, and 28 for the training comparison (7 professional weight lifters, 7 professional bobsleigh sprinters, 14 untrained men)

Intervention

Knee bends, squatting, walking, 200 m running, 10 minutes of cycling, static loading and 40 cm drop jumps, with quantitative MRI of cartilage volume before and after

Comparator

Within-subject before and after each activity; athletes against untrained men for knee bends

Limitations

Small physiological samples in healthy knees; acute volume change is a surrogate, not a disease outcome; femorotibial changes sit close to the method's own precision error, and recovery time was not measured in this study.