Aims. The aim of this study was to analyse human muscle tissue before
and after rotator cuff repair to look for evidence of regeneration,
and to characterise the changes seen in the type of muscle fibre. Patients and Methods. Patients were assessed pre-operatively and one year post-operatively
using the Oxford Shoulder Score (OSS) and MRI. The cross-sectional
area and distribution of the type of muscle fibre were assessed
on biopsies, which were taken at surgery and one year post-operatively.
Paired samples from eight patients were analysed. There were three
men and five women with a mean age of 63 years (50 to 73). Results. All but one patient showed improvement in OSS (p = 0.004). The
mean increase in the cross-sectional area of the muscle was 1220 μm. 2. (-801
to 3712; p = 0.03). There was a reduction of type 2a fibres (p =
0.02). A clear relationship could not be seen between the MRI findings and
the histological appearances. Conclusion. This is the first study to provide evidence that atrophy of the
supraspinatus muscle is reversible. Changes in the types of fibre
are discussed. MRI assessment of muscle atrophy may not be fully
representative of
