In vivo precision of quantitative shoulder cartilage measurements, and changes after spinal cord injury

Recent advances in MRI have enabled the quantitative assessment of articular cartilage morphology in human joints. In this study, we tested the hypothesis that the precision of quantitative shoulder cartilage measurements is sufficient to detect changes between and within patients, and that shoulder cartilage thickness in paraplegic patients increases due to increased loading. We imaged the shoulders of seven healthy volunteers four times using a coronal 3D, fat-suppressed, gradient-echo sequence. The humeral head cartilage in seven paraplegic patients was evaluated soon after injury and 1 year post injury. A precision of 4.5% (root mean square (RMS) average coefficient of variation (CV) %) was found for shoulder cartilage thickness measurements in the humeral head. Whereas a significant decrease of cartilage thickness (-11%, P < 0.05) was observed in the knee, there was no significant change in articular cartilage thickness in the shoulder (-1.1%). Our data show, for the first time, that articular cartilage of the humeral head can be quantified with acceptable precision in vivo. It was demonstrated that, in contrast to the knee, the articular cartilage morphology of the humeral head changes very little (i.e., there is no significant increase or decrease in thickness) after spinal cord injury (SCI).