A comparison between a patient-specific bone regenerative implant and the osteochondral allograft procedure in a Hill-Sachs lesion, a cadaveric study.

BACKGROUND: Anterior shoulder instability with >30% humeral bone loss is typically treated with an osteochondral allograft (OCA), though complications and reoperation rates remain high (20%-30%). New methods such as 3D printing are being researched to mitigate these results. This study compares the surface geometry and biomechanical integrity of a 3D-printed biodegradable, patient-specific bone regenerative implant (O3D) to traditional OCA in the treatment of Hill-Sachs lesions (HSLs). METHODS: In 14 cadaveric shoulders, HSLs were created in a uniaxial biomechanical set-up and confirmed using imaging. The shoulders were randomized over 2 groups: group A, OCA surgery, and group B, magnesium phosphate-polycaprolactone 3D-printed implant (O3D). After the reconstruction of the HSLs, imaging was performed to measure surface morphology and articular congruence. Finally, uniaxial biomechanical testing was performed to measure postimplantation stability. RESULTS: The average force needed to create a HSL was 1120 N. Implant surface area and joint surface area showed no significant difference between the groups (P = .69 and P = .48). Articular step-off and implantation gap showed no significant difference (P = .67 and P = .54). However, O3D demonstrated significantly better joint congruence (1.26 ± 0.29 mm) than OCA (3.17 ± 1.43 mm, P = .044). Breakout compression forces were not significantly different (P = .80) between the groups: OCA (152 ± 91 N) vs. O3D (144 ± 37 N). Micro computed tomography revealed differing failure mechanisms: cortical compression in OCA vs. layer deformation in O3D, reflecting their respective architectures. CONCLUSION: Both OCA and O3D implants effectively restored joint integrity in large HSLs. The O3D implant showed superior congruence and equivalent biomechanical performance, illustrating a 3D-personalized, regenerative alternative to allografts.