['Reattachment of the supraspinatus (SSP) tendon after spontaneous rupture leads to improved shoulder function. Whether this improvement of function is due to a reversal of muscle atrophy and fat accumulation known to occur after SSP rupture is still debated. Our previous study of late reattachment of SSP (12 weeks) failed to confirm a reversal of muscle atrophy and of fat accumulation.', 'To find out whether earlier reattachment (6 weeks) reverses atrophy and fat accumulation of the SSP.', 'Reattachment group: in seven rabbits unilateral supraspinatus detachment, reattachment after 6 weeks and killing 6 weeks later. Detachment group: in seven rabbits unilateral supraspinatus detachment and killing 12 weeks later. The contralateral shoulders served as controls (n=14). Determination of the supraspinatus constituents: muscle, extra- and intramuscular fat in volume and cross-sectional area.', 'Muscle tissue in the reattachment group (8.6 ml+/-1s.d.=0.6) and in the detachment group (8.9 ml+/-0.9) were less than in control supraspinati (10.2 ml+/-0.9, both p<0.05). Extra- and intramuscular fat in the reattachment group (8.7%+/-3.2) was greater than in both, the detachment group (4.6%+/-3.5), and control supraspinati (2.8%+/-1.7, both p<0.05).'] Does early reattachment reverse atrophy and fat accumulation of the supraspinatus -- an experimental study in rabbits?