RESUMO
Purpose of this study was to investigate the biomechanical fates of the partial thickness tear of the rotator cuff in rabbit, and try to provide guideline of treatment for the partial thickness tear of the rotator cuff tendon. Infraspinatus tendons of fifty rabbits were used for study. The rabbits were divided into three groups, twenty for one-third resection(superficial partial resection group), twenty for two-thirds resection(deep partial resection group) and ten for control group. Extraarticular portion of the infraspinatus tendons of the rabbits were resected partially with one-third or two-thirds thickness for each experimental group. We sacrificed five rabbits of each experimental group at 3, 6, 9, and 12 weeks after the resections, and five rabbits for the control group at 6 and 12 weeks. Average maximal load per area of the infraspinatus tendons was measured by tension test. There was significant difference between the deep partial resection group, 5.3 and 6.3 N/emat 6 and 12 weeks respectively, and the control group, 13.2 N/mm(P<0.05). There was no difference between the control and superficial partial resection group, 12.8 and 14.1 N/mm at 6 and 12 weeks, respectively. Shallow partial tears might be healed spontaneously. Deep partial tears would not be healed naturally. When surgical treatment is indicated for deep partial tears of the rotator cuff, tendon repair, rather than debridement, would provide more predictable results.