Shoulder instability often results in both humeral and glenoid lesions. The Latarjet is a commonly used procedure to address glenoid bone loss but does not specifically address humeral lesions. Further, the concept of the glenoid track has been described to predict which humeral lesions contribute to shoulder instability. The purpose of this study was to determine if preoperative computerized tomography (CT) imaging can predict coracoid graft size and conversion of off-track to on-track Hill-Sachs lesions in patients undergoing Latarjet procedures. We hypothesized that coracoid graft size, and therefore amount of glenoid reconstruction, could be accurately predicted based off preoperative CT imaging.
Patients who underwent Latarjet procedure at a single institution from 2012-2020 were evaluated. Inclusion criteria consisted of pre- and post-operative advanced imaging (CT or magnetic resonance imaging, MRI). Patient information was obtained via chart review. Preoperative CT scans were reviewed to determine glenoid bone loss, via best-fit circle method, and the Hill-Sachs interval. Off versus on track was then determined. Additionally, the preoperative CTs were used to measure coracoid dimensions including its total length, height, and depth/thickness. Postoperative CT or MRIs were then reviewed to measure the height and width of the graft, as well as the new glenoid diameter. Using the dimension of the previously measured Hill-Sachs interval, new on vs off track status was calculated.
Fourteen patients met the inclusion criteria. The average Hill-Sachs interval was 20.9±6.0mm with an average glenoid track of 18.9±2.5mm. Overall, 8 patients had off-track lesions. The average glenoid bone loss was 23.9±0.8%. The harvested coracoid graft was 65.4±9.5% of the length and 102.1±17.2% of the depth of the preoperative measurements. The predicted new glenoid diameter was 35.1±3.8mm and reconstructed 99.1±7.7% of the predicted diameter, or 34.7±4.0mm. Overall, 13 of the 14 patients had their lesions converted to on-track lesions.
This study shows that preoperative CT measurements of the coracoid can predict Latarjet coracoid graft width, and to a lesser extent, graft length. When factoring in preoperative measurements of the glenoid, one can estimate the amount of glenoid that can be reconstructed with a Latarjet, as the glenoid bony diameter was restored to 99.1% of the preoperatively calculated size. By performing these measurements, one can predict whether an off-track Hill-Sachs can be converted to on-track, further enhancing shoulder stability.