抄録
We reported that the cross-sectional area ( CSA ) by MRI did not show any significant recovery until postoperative one year, however the muscle strength of shoulder showed significant recovery after the operation. In this study, we evaluated the changes of thickness of the infraspinatus ( ISP ) by ultrasonography after arthroscopic rotator cuff repair, and investigated the differences with CSA of it and the differences of thickness of it between static state ( at rest ) and dynamic state ( active ).
We investigated 27 cases ( 16 males and 11 females ) that had ultrasonography and MRI before operation, 6 months and 1 year after the operation. The mean age at operation was 60.9 years old ( 48 - 78 ). The thickness of bi-lateral sides were measured by ultrasonography at rest and active. The point of the measurement was medial 1/4 and 3cm inferior from the scapula's spine. We measured CSA in the inside 1cm part from the joint with an MRI oblique-sagittal T2 image. Changing in thickness on the affected side: it changed from 11.1mm to 11.3mm to 11.7mm at rest. It changed from 13.2mm to 13.9mm to 14.5mm on active. The thickness at rest did not show a meaningful change, but showed a statistically significant increase at both postoperative 6 months and 1 year. Changing of CSA: it changed from 4.76cm 2 to 4.49cm2 to 4.57cm2. We showed a significant decrease in the postoperative 6 months.
ISP muscle volumes of static state ( the thickness of ISP at rest and CSA ) did not increase, but it's dynamic state ( the thickness of ISP on active ) increased significantly. We thought that the muscular fiber's volume increased to respond to recovery of a nervous factor. The measurement of thickness of dynamic state is a very useful method to evaluate the recovery of a muscle after an operation.
