Patients with anterior shoulder instability are at increased risk of developing glenohumeral arthritis. T2-mapping is a quantitative magnetic resonance imaging (MRI) modality which allows for the non-invasive measurement of cartilage health and injury. T2 relaxation times are affected by collagen structure and water content and have been shown to be elevated in injured cartilage and the development of arthritis.
This study utilized T2-mapping MRI to evaluate glenoid and humeral head cartilage health in individuals who underwent operative stabilization for anterior shoulder instability with mid-term follow up.
Six patients (mean age 36.2 years; range 23-46 years) with a history of anterior shoulder instability and who underwent arthroscopic stabilization had MRI T2-mapping of their bilateral glenohumeral joints at a minimum of 4 years after operative stabilization of the shoulder (range 48-73 months). The contralateral, healthy, shoulder served as a control for the MRI T2-mapping. None of patients suffered a recurrent dislocation postoperatively. Glenoid and humeral head cartilage was divided into anterior and posterior regions on axial MRI views, and T2-mapping relaxation values were measured for each region within both operatively stabilized and healthy contralateral control shoulders.
T2-mapping relaxation values for glenoid cartilage in the operative shoulder were significantly greater than in control shoulders (32.2 ± 5.42 ms vs 27.7 ± 4.57 ms, P = 0.003). However, T2-mapping relaxation values for humeral cartilage were not significantly different in the operative group compared with controls (29.4 ± 5.19 ms vs 27.9 ± 3.89 ms, P = 0.212). When examined regionally, T2-mapping relaxation values in the anterior glenoid region trended toward significant differences in the operative group compared with controls (31.5 ± 4.81 ms vs 29.1 ± 4.21 ms, P = 0.123). T2-mapping relaxation values in the posterior glenoid region were significantly higher in the operative group compared with controls (33.7 ± 5.96 ms v 26.3 ± 4.47 ms, P = 0.012).
Glenoid cartilage demonstrated significantly greater T2-mapping relaxation values in patients with anterior instability treated with arthroscopic stabilization compared to contralateral control shoulders when evaluated by T2-mapping quantitative MRI at a minimum of 4 years post-operatively. Region specific T2-mapping relaxation values were higher in the glenoid cartilage for those patients stabilized arthroscopically compared to their contralateral healthy shoulder. These findings suggest that initial cartilage damage from shoulder dislocation events may predispose patients to irreversible glenohumeral cartilage injury despite operative stabilization.