A Large Humeral Avulsion of the Glenohumeral Ligaments Decreases Stability That Can Be Restored With Repair

Abstract

Humeral avulsion of the glenohumeral ligaments (HAGL) has become a recognized cause of recurrent shoulder instability; however, it is unknown whether small and large HAGL lesions have similarly destabilizing effects and if large lesion repair results in restoration of stability. In a cadaver model, we evaluated the effect of small and large HAGL lesions and large HAGL lesion repair on glenohumeral ROM, translation, and kinematics. We measured rotational ROM, humeral head translation under load, and humeral head apex position in eight cadaveric shoulders. Each specimen was tested in 60° glenohumeral abduction in the scapular and coronal planes under four conditions: intact, small HAGL lesion (mean ± SD length, 18 ± 1.8 mm), large HAGL lesion (36.8 ± 3.6 mm), and after large HAGL lesion repair. For each condition, we measured maximum internal and external rotation with 1.5 Nm of torque; glenohumeral translation in 90° external rotation with 15- and 20-N force applied in the anterior, posterior, superior, and inferior directions; and humeral head apex position throughout ROM. Repeated-measures ANOVA was used for statistical analysis. Small HAGL lesions did not change ROM, translation, or kinematics from the normal shoulder; however, these parameters changed with large HAGL lesions. Maximum external rotation and total ROM increased in the scapular (13.8° ± 9.4°, p < 0.001; 19.0° ± 16.5°, p < 0.001) and coronal (21.4° ± 10.6°, p < 0.001; 29.1° ± 22.1°, p < 0.001) planes. With anterior force, anterior-inferior translation increased in both planes (mean increase for both loads and planes: anterior: 9.1 ± 9.5 mm, p < 0.01; inferior, 5.7 ± 6.6 mm, p < 0.03). In the coronal plane, posterior and inferior translation also increased (4.9 ± 5.4 mm, p < 0.01; 7.1 ± 9.9 mm, p < 0.03; averaged for both loads). The humeral head apex shifted 3.7 ± 4.9 mm anterior (p = 0.04) and 2.8 ± 2.6 mm lateral (p = 0.004) in the scapular plane and 3.7 ± 3.4 mm superior (p = 0.006) and 4.1 ± 2.6 mm lateral (p < 0.001) in the coronal plane. HAGL lesion repair decreased ROM and translation in both planes and restored humeral head position in maximum external rotation. Anterior large HAGL lesions increase ROM and glenohumeral translation. After large HAGL lesion repair, stability of the shoulder can be restored. Surgeons should be aware of the possibility of HAGL lesions in patients with shoulder instability, and if large HAGL lesions are diagnosed, surgeons should consider repairing the lesions.