On 2 April at 15 Madis Rahu will defend his doctoral thesis „Structure and blood supply of the postero-superior part of the shoulder joint capsule with implementation of surgical treatment after anterior traumatic dislocation“.
Professor Jüri Kartus (PhD, Department of Orthopaedics at Institute of Clinical Sciences, University of Gothenburg, Rootsi).
Professor Anne Agur (PhD), Division of Anatomy, Department of Surgery, Toronto University, Kanada.
Traumatic anterior traumatic joint dislocation is the most frequent joint dislocation in humans, with a high reported recurrent rate in adolescents less than 25 years of age after initial conservative treatment. In the case of shoulder joint anterior dislocation, the humerus head shifts over the antero-inferior edge of the articular cavity of the shoulder blade and hooks behind this edge with the postero-superior surface of the humerus head. In the course of this injury, often a bone defect, which is called the Hill-Sachs lesion, appears in the postero-superior part of the humerus head.
Earlier biomechanical studies on cadaver material have proved that intra-articular cutting of the postero-superior part of the shoulder joint capsule without injuring the tendon part of the rotator cuff increases the shoulder joint dislocation in the antero-inferior direction by 45-50%. Depending on the shoulder joint anterior dislocation mechanism, the authors of this study posed the question whether the forward shift of the shoulder joint is also accompanied by injuries in the postero-superior structures of the joint capsule. Which structures are injured and what is the clinical significance of these injuries?
Therefore, the main aim of our research group was clarification of the anatomical structures of the postero-superior part of the shoulder joint and their blood supply. At macroanatomical preparation (on cadaver material), we found that the superior part of the shoulder joint capsule is closely connected with the tendons of the rotator cuff muscles, which in the superior part of the joint capsule are reinforced by a curved structure, the so-called rotator cable (lig. semicirculare humeri). The posterior attachment site of the rotator cable is also the area joining the three tendons of the rotator cuff muscles (m. supraspinatus, infraspinatus and teres minor). The research also confirmed the existence of an anatomically constant connective tissue structure, the so-called lig. glenocapsulare in the postero-superior part of the shoulder joint capsule whisc was previously described by Dr. Kolts in conference abstracts in 2000. This capsule structure is attached from the shoulder blade to the postero-superior part of the rotator cable, which, in its turn supports the rotator cuff, as described in his study.
As another aspect, we described the joint capsule injuries found during the clinical study in patients aged below 25 years in the case of first-time traumatic anterior dislocation of the shoulder joint. During the operations we found that, differently from the data of earlier articles, more than 50% of patients had injuries in the postero-superior part of the joint capsule. Most of these were surface injuries. In these cases, relying on earlier literature sources, we removed the open injured part in the region of the injured joint capsule and, thereafter, restored the antero- inferior capsule structures. The follow-up two years later showed that the earlier activities provided similar results compared to patients who had no injuries of the postero-superior part of the shoulder joint capsule.
Considering the blood supply of the shoulder joint capsule and its surrounding anatomical structures and the course of blood vessels in these structures, we developed an operation technique for repair of engaging Hill-Sachs lesions. According to this modified operation remplissage technique, the sutures should run in parallel with muscle fibres, involving the tendon part of the muscle (m. infraspinatus) and the posterior attachment site of the rotator cable to avoid interruption in the blood supply of the muscle. We also recommend using an analogous technique in the case of minor non-engaging Hill-Sachs injuries where the posterior attachment site of the rotator cable is also damaged.