In vivo arthroscopic cartilage stiffness measurement in the knee.

The purpose of this study was to map the biomechanical properties of normal human articular cartilage in vivo. Instantaneous compressive stiffness was measured in the knee articular cartilage of 87 patients. Lateral femoral condyle stiffness (mean +/- SD; 5.12 +/- 1.02 N) was greater than at all other sites and was significantly greater than mean values obtained for the medial femoral condyle (4.8 +/- 1.22 N), medial and lateral trochlea (4.2 +/- 0.92 and 4.6 +/- 1.27 N, respectively), medial and lateral patella (3.1 +/- 0.66 N and 3.3 +/- 1.01 N, respectively), and medial and lateral tibial condyle (2.4 +/- 1.17 N and 3.2 +/- 1.16 N, respectively) for all subjects (P < .05, Wilcoxon signed-rank test). This study enabled comparison measures of suspected degenerative cartilage.