Stress behaviors of distal femoral cartilage defect and repair

Abstract

Objective: To find contact stress distributions of femoral condyle cartilage under defect and repaired status. Methods: 6 mini-pigs were selected to divide into intact group, defect group and repair group. 4 pigs in defect group were performed 4 types of cartilage defect, including circle, triangle, square and trapezoid. Defect samples were repaired with two kinds of artificial cartilages. Contact stress distributions of joint contact surfaces were measured and analyzed using thin-film pressure sensor under standard standing loads. Results: The maximum stress in the stress concentration area caused by cartilage defect were enhanced by 3.4 or 4.6 times of normal stress, even 6.2 times. The soft artificial cartilage fixation caused abnormal stress distribution at the defect area. Hard artificial cartilage was close to the level of natural cartilage. Stress concentration at the defect edge was almost eliminated, but the stress distribution in the whole contact area was still different from intact group. In addition, the peak stress point changed in the defect group and repaired group while compared with intact group. Conclusions: Cartilage defect resulted in the variations of original intact contact stress distribution. Artificial cartilage repairing could relieve stress concentration but not recover to healthy status yet. Our findings could provide evidences for better rehabilitation of articular cartilage injury.