抄録
The thickness of the articular cartilage of the humeral head and that of the glenoid fossa were measured, and their dynamic properties were compared.
This study was performed on 22 cadavaric shoulder joints without a rotator cuff tear or macroscopic damage to the cartilage. The humeral head was dissected with a bone cutter along the plane parallel to and that perpendicular to the humeral axis that passes the center of the humeral head; and the glenoid cavity, along the perpendicular plane and the horizontal plane that divides it into 3 equal parts; and the respective cartilages, thickness were measured with a caliper. Then, the gleno-humeral angle formed by the humeral head contacting the glenoid fossa with the intervention of the thickest part of the cartilages was reproduced on the cineradiograms of 30 normal shoulders by elevating and dropping the arm in the sitting position, to measure the gleno-humeral angle.
The cartilage of the humeral head was the thickest, i. e., 2.2±0.5mm(p<0.05), at the part in about 10° inferior direction of the humeral axis from the center of the head; and the glenoid articular cartilage, significantly thicker, i. e.,3.5±0.8mm(p<0.01), at the parts in the antero-inferior direction, and also significantly thicker, i. e.,3.5±0.9mm(p<0.01), in the inferior direction. The mean gleno-humeral angle was 77.0±6.8°, which was mostly consistent with the zero position on the cineradiogra ms.
The glenoid fossa was markedly varied in thickness from part to part. It may probably be for that reason that the contacting area of the glenoid fossa is more limited than that of the humeral head when the shoulder becomes the joint needing support. The zero position appears to be not only the relaxed position but also the position with the greatest load on the articular surface.
