Abstract
Purpose of the study: Four elements differentiate myotendinous tears of the infraspinatus from other rotator cuff tears: the tendon insertion on the trochiter and the joint capsule are spared; the onset in characterized by intense muscle oedema followed at 6 to 12 months by severe and definitive fatty degeneration.
Material and method: Fifty-nine myotendinous tears of the infraspinatus were collected prospectively from 1993 to 2007. Female gender predominated (58%); trauma was noted at onset in 22% of the shoulders and the mean age of discovery was 48.9 years. Twenty-nine shoulders were seen at the acute phase with significant muscle oedema recognized on the MRI T2 Fat Sat sequence. A second group of 30 patients had grade 4 fatty infiltration of the infraspinatus without full thickness cuff tears. The EMG was available for 23 shoulders and was normal in all, ruling out a neurological cause. Associated lesions of the supraspinatus and infraspinatus tendons were: tendon calcification (61%) and partial tears at the acute phase (21%) and chronic phase (70%) suggesting a degenerative cause.
Results: Twenty-four patients underwent surgery and 35 had a medical treatment. At mean 46 months follow-up (range 12–125) the Constant score improved from 51.7 to 69.4 points (p< 0.0001). There was no different statistically between the operated and non-operated patients (p=0.325). All patients seen at the acute phase of the oedema progressed to complete grade 4 fatty degeneration of the muscle, irrespective of the treatment delivered.
Discussion: Early diagnosis of this lesion can be achieved with T2 Fat Sat MRI sequences. Arthroscopic repair to tighten the infraspinatus muscle could avoid the irremediable degeneration with total loss of muscle function.
Correspondence should be addressed to Ghislaine Patte at sofcot@sofcot.fr
