CONCEPTS OF THE SHOULDER JOINT INSTABILITY FORMATION

The all-round study of the shoulder joint structure and function permitted to determine that the shoulder head stability is ensured by the participation of all anatomic structures, including not only bursa-ligamentous apparatus, bone structures but also the connective tissue, fatty tissue. Micro- and macrotraumas or mixed forms of lesion, as well as functional overstrain have significant influence on the formation of the shoulder joint instability (SJ), weakening of the shoulder head supporting apparatus (SHSA). In case of SHSA weakening, conditions for position instability arise, the shoulder joint bursa becomes wider, therefore the reverse muscle reaction through the peripheral and CNS cannot secure functionally beneficial spatial location in the joint cavity.

The revelation of shoulder joint instability at the early stage is possible with the help of functional tests using rotatometer developed by us. The results of a number of examinations permitted to determine that the anatomic factor of the shoulder head stabilization is not always the index of functional joint stability. If the adaptative mechanisms of self-regulating SHSA system can compensate the function of the shoulder head support lost as the result of trauma, joint instability can be absent.

The constant muscle strain that secures the head stability by its tonic contraction, inactivity of the second muscle groups, overstrained tendons that cause dysbalance and destroy of reflectory reverse connection make up shoulder joint instability. With the lesion and distention of bursa-ligamentous apparatus, the position instability can take place in the definite shoulder movements when the head is at the weakened segment of capsular bursa. Shoulder joint instability is accompanied by limitation of external shoulder rotation, and its axis in functionally beneficial position cannot coincide with the angle of retroversion. Therefore, functional SJ instability is formed by the combination of mechanic SHSA lesions and destroy of reflectory SJ connections.

A.B. Galicnko, B.I. Galienko  
N. I. Pirogov Vinnitsa National Medical University, the City Clinical Hospital, Vinnitsa, Ukraine.

 

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