抄録
The collagen fibrils of rotator cuffs were analyzed quantitatively from the transmission electron microscopic photographs.
(Materials and methods) Specimens of rotator cuffs were obtained from 22 patients aged 44 to 81 who had undergone surgery. Eighteen cases of rotator cuff tear (massive 7, large 4, medium 6 and small 1)and 4 cases of non-tear (fracture 2, calcium deposit 1 and impingement 1) were available. In the rotator cuff tear cases, the biopsies from the superficial and deep layers of the proximal stump(PS&PD), distal stump(D) and non-torn site(N) were performed. In the non-tear cases, biopsies from the superficial and deep layers(SL&DL) were carried out. Collagen fibrils were magnified 150.000 times by electron microscope. Quantitative analysis of the collagen fibrils were performed using a personal computer: the fibril diameter, the occupied area percentages (the sum of each fibril area/total area X 100 %) and the fibril density (the number of fibrils per square micro-meter).
(Results) The average diameter: PS 50nm, PD 45nm, D 44nm, N 48nm, SL 68nm and DL 59nm. In PS, unimodal diameter distributions (small diameter peak at 50 nm) were observed in 13 of 18 cases (72%). In SL, bimodal diameter distributions (small diameter peak at 50 nm and large diameter peak at 120 nm) were observed in 3 of 4 cases(75%), The average occupied area percentages: PS 48%, PD 44%, D 43%, N 54%, SL 53% and DL 46%. The average densities: PS 172, PD 208, D 193, N 208, SL 113 and DL 143.
(Conclusion) In both the rotator cuff tear group and the non-tear group, the average diameters of collagen fibrils were larger in the superficial layers than in the deep layers. The mass-average diameter of collagen fibrils in non-tear cases was larger than that in the tear cases. The non-tear cases have bimodal distributions which are made up of large and small diameter fibrils. On the other hand, the tear cases have unimodal distributions which are made up of small diameter fibrils. In tear cases, the large diameter fibrils may become small because the tensile stress decreases.
