Arthrolyse antérieure de l’épaule sous arthroscopie dans les séquelles de paralysie obstétricale du plexus brachial. Résultats préliminaires

L’objectif de cette étude est d’apprécier les résultats de l’arthrolyse antérieure sous arthroscopie de l’épaule dans les raideurs en rotation interne secondaire à une paralysie obstétricale haute du plexus brachial (C5, C6 ± C7). Chez huit enfants sur 14 présentant une rétraction en rotation interne de l’épaule, une arthrolyse antérieure avec respect des muscles subscapulaire et grand pectoral a été réalisée. Dans tous les cas un transfert du muscle latissimus dorsi a été associé. L’âge moyen lors de l’intervention était de trois ans et six mois. Les huit cas ont été revus avec un recul minimum de 12 mois et moyen de trois ans. Seules les mesures des rotations externe et interne passives ont été prises en compte en raison de l’âge des enfants. Les résultats montrent un gain sur la rotation externe de 50° en moyenne avec conservation de la rotation interne selon la cotation de Mallet et une amélioration importante du mouvement d’abduction–antépulsion. Aucune récidive n’a été notée. Ces résultats montrent que l’arthrolyse sous arthroscopie précoce et limitée au plan capsuloligamentaire antérieur et supérieur permet d’obtenir des résultats comparables aux autres techniques quant au mouvement de rotation externe passive. De plus, en conservant le muscle subscapulaire, elle limite le risque d’instabilité antérieure de l’épaule et permet de conserver la mobilité active en rotation interne. Son indication reste limitée dans les raideurs en rotation interne avec luxation postérieure de l’épaule.

Purpose of the study

Retraction of the shoulder in internal rotation is observed in 25% of children with brachial plexus birth palsy (C5, C6 ± C7). Early bone and joint deformities affecting the glenohumeral joint are the consequences. The stiff internal rotation requires surgical release which can involve the capsule and ligaments, muscles, or both. Internal release can be combined with muscle transfer to improve active external rotation. We report the results obtained with arthroscopic anterior capsular release combined with latissimus dorsi transfer.

Material and methods

From 1999 through 2006, fourteen children with a stiff shoulder in internal rotation secondary to brachial plexus birth palsy were managed in our unit. All had recovered biceps function six months after surgery. The glenohumeral dysplasia was analyzed on the preoperative magnetic resonance imaging. Pre- and postoperative passive external rotation (RE) were measured with the arm along the body and at 90° elbow flexion. Internal rotation was measured using the Mallet score (hand-back test). Combined active abduction antepulsion was measured when the child was playing. Mean age at surgery was three years six months. Arthroscopic internal release was performed for eight children. All had an associated latissimus dorsi transfer.

Results

Among the 14 children managed in the unit, arthrolysis was not be performed in six, either because of the lack of an adequate electrode (two patients) or because the child presented posterior glenohumeral dislocation making it impossible to introduce the optic channel (four patients). Arthroscopic anterior release was performed for the eight other patients. These eight patients were reviewed at a mean three-year follow-up. Passive external rotation was improved, with a mean gain of 60° with no recovery of passive internal rotation. The abduction antepulsion movement was also improved, mean gain 90°.

Discussion

A stiff shoulder in internal rotation can develop during the first two years of life. Several techniques have been proposed for internal release. The origin of the progressive limitation of passive external rotation remains a subject of debate. Is it due to retraction of the internal rotators, or to capsule–ligament retraction, or both? In 1992, Harryman et al. demonstrated the role of the capsule and the coracohumeral ligament in limiting external rotation. Consequently, we have opted for early release (less than two years of age) using an arthroscopic method limited to the capsule and ligaments. Our results for passive external rotation are comparable to those reported by others. However, this technique enables preserved mobility for internal rotation.

Conclusion

Arthroscopic anterior release limited to the capsule and the ligaments is an effective, minimally invasive technique. Leaving the internal rotator muscles intact preserves internal rotation of the shoulder and reduces the risk of anterior instability.