Golijanin P, Arner JW, Ryan CB, Zai Q, Peebles LA, Peebles AM, Ganokroj P, Whalen RJ, Eble SK, Rider D, Ninković S, and Provencher MT
Background: The concept of on-track versus off-track bone lesions in glenohumeral instability continues to evolve. Although much has been ascertained from an original biomechanical model, bony pathological changes, especially on 3-dimensional (3D) imaging, have not been fully evaluated., Purpose: To compare the differences in on-track versus off-track lesions to characterize glenoid and humeral head bone defects using 3D modeling software., Study Design: Cross-sectional study; Level of evidence, 3., Methods: A consecutive cohort of 75 patients with recurrent anterior instability, with evidence of Hill-Sachs lesions (HSLs) and glenoid bone loss (GBL) and a mean age of 27.1 years (range, 18-48 years), were reviewed. 3D models of unilateral proximal humeri and glenoids were reconstructed. The volume, surface area, width, and depth of identified HSLs were quantified, along with their location (medial, superior) and orientation (Hill-Sachs angle). The percentage, width, and length of GBL as well as the glenoid track status were calculated. The on-track and off-track groups were compared using the Mann-Whitney U test., Results: The off-track group had greater HSL surface area (374.23 vs 272.64 mm 2 , respectively; P = .001), more HSL medialization (14.96 vs 17.62 mm, respectively; P = .028), greater HSL volume (603.08 vs 433.61 mm 3 , respectively; P = .007), and a greater mean HSL width (16.06 vs 11.53 mm, respectively; P = .001) than the on-track group. The off-track group also had greater GBL (22.55% vs 17.73%, respectively; P = .037), a greater GBL width (6.92 vs 3.58 mm, respectively; P < .001), and a greater GBL length (21.61 vs 16.1mm, respectively; P = .015) than the on-track group. Further analysis of large off-track lesions revealed a greater Hill-Sachs angle (33.16° vs 26.20°, respectively; P = .035) and a more superior extent of HSLs compared with borderline off-track and on-track lesions., Conclusion: Off-track lesions were found to have larger GBL, a larger HSL width, a more medialized HSL, and greater HSL surface area. This study outlines the specific characteristics of high-risk bipolar bone loss lesions to simplify the identification of patients in a clinical setting and aid in appropriate treatment planning., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: J.W.A. has received hospitality payments from Arthrex, Mid-Atlantic Surgical Systems, and Smith+Nephew; education payments from Mid-Atlantic Surgical Systems; and grants from Arthrex and DJO. C.B.R. has received grants from Arthrex and DJO and education payments from Smith+Nephew and MedInc of Texas. M.T.P. has received royalties from Anika Therapeutics, Arthrex, and Arthrosurface; consulting fees from Arthrex, Zimmer Biomet, and JRF Ortho; nonconsulting fees from Arthrex and Arthrosurface; education payments from Arthrex; and honoraria from Flexion Therapeutics and JRF Ortho. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2024.)