PURPOSE OF THE STUDY Shoulder instability is often times accompanied by associated injuries caused by the humeral head displacement. These are primarily bone lesions on the head and socket of the glenohumeral joint. The purpose of this study was to evaluate the frequency, morphology and clinical significance of bone lesions in shoulder instabilities in a group of patients operated in our department for glenohumeral instability between 2012 and 2019. MATERIAL AND METHODS The ongoing evaluation included 373 patients with trauma and habitual instability who had undergone surgery in our department in the period from 2012 to 2019. All patients underwent a preoperative 3D CT scan of the shoulder joint. Subsequently, the morphology and clinical significance of individual bone lesions were evaluated based on the older Burkhart s concept of engaging/nonengaging lesions and the newer concept of glenoid track by Yamamoto and Di Giacomo of 2007, 2014 or 2020. RESULTS The frequency of Hill-Sachs lesion was 83.4% (311) in our group of patients. In nearly two thirds (211 cases) also a bone defect on glenoid was detected (59.3%). When comparing the basic types of instabilities, in the TUBS group the Hill-Sachs lesions were present up to twice as often as in the group with AMBRI instability. Clinically significant Hill-Sachs lesions according to the older concept of engaging/ nonengaging lesions of Burkhart were reported in 104 cases (34%). Clinically significant lesions according to the newer concept of Yamamoto and DiGiacomo (the so-called off-track lesions) were observed in 173 cases (55.6%). Classified as critical were the clinically insignificant lesions (the so-called on-track lesions), which by their location were near the glenoid track. These lesions were found in 80 patients. After adding up the significant (off-track) and critical on-track lesions, we arrived at 253 (81.4%) clinically significant lesions based on the updated Yamamoto concept. DISCUSSION The frequency of Hill-Sachs lesions and glenoid defects identified by us is close to the upper limit of the range described in literature (8 to 100%). Based on the recent study by Yamamoto, added to these defects were the so-called peripheral ontrack defects, the clinical significance of which is currently indisputable. The oldest classification into engaging/nonengaging lesions revealed only 34% of the significant lesions, but this concept does not evaluate the glenoid defect. The newer concept by Yamamoto/DiGiacomo resulted in detecting 55.6% of significant Hill-Sachs lesions. The latest modification of the glenoid track of 2020, which includes also the on-track lesions in the critical zone among the significant lesions, in our group of patients classified 81% of lesions as clinically significant. CONCLUSIONS Our study confirmed the very frequent occurrence of clinically significant Hill-Sachs lesions in shoulder instabilities. Therefore, for the sake of successful shoulder stabilisation surgery detailed preoperative planning with 3D CT of the shoulder joint and evaluation of the associated bone lesions are necessary. The highest detection of clinically significant lesions was achieved by the latest modification of the glenoid track concept. Future studies will have to prove the effect of this classification on the result of surgical treatment. Key words: shoulder instability, glenoid track; bone defects, Hill-Sachs lesion; bipolar lesions; 3D CT evaluation.

Aplikační centrum BALUO Fakulta tělesné kultury Univerzity Palackého v Olomouci

Ortopedická klinika Lékařské fakulty Univerzity Palackého v Olomouci a Fakultní nemocnice Olomouc

Incidence, Morphology and Clinical Significance of Hill-Sachs Lesions in Shoulder Instability - CT Scan Evaluation of the Group of Patients

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