A comparison between a patient-specific bone regenerative implant and the osteochondral allograft procedure in a...

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).

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.

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.

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.