Force isocinétique des muscles rotateurs de l’épaule dans l’instabilité chronique antérieure

Is the subscapularis normal after the open Latarjet procedure? An isokinetic and magnetic resonance imaging evaluation

BACKGROUND

The Latarjet procedure is considered to be a violation of the subscapularis muscle. This study evaluated the postoperative status of the subscapularis through isokinetic and magnetic resonance imaging analysis after splitting. We hypothesized that compared with a healthy contralateral shoulder, there would be satisfactory recovery of subscapularis strength at the cost of some fatigability and some mild fatty infiltration.

MATERIALS AND METHODS

This was a case-control retrospective study of patients who underwent a Latarjet procedure between January 2013 and January 2015. A total of 20 patients were reviewed at 1 year postoperatively. With the patient seated, strength testing of both shoulders was done (concentric, eccentric, and fatigability) with a dynamometer. Trophicity and fatty infiltration were analyzed by magnetic resonance imaging.

RESULTS

Strength of the internal rotators (IRs) and external rotators (ERs) of the injured shoulder was significantly lower compared with the healthy shoulder in concentric testing at 180°/s and 60°/s (13% for IR and 20% for E, P < .05) and in eccentric testing at 60°/s (19% for IR and 16% for ER, P < .05). A peak torque ratio (ER/IR) of the operated-on shoulder was maintained. The difference in muscular endurance was significant (P < .001). There was no muscle atrophy and minimal or no fatty infiltration of the subscapularis in any patient.

CONCLUSION

At 1 year after the open Latarjet procedure, isokinetic testing showed a combined strength deficit in both internal and external rotation with a conserved muscle balance. Although no significant subscapularis fatty infiltration or atrophy was noted, there was a significant deficit in endurance compared with the healthy shoulder.