Summary

Talus Osteochondral Allograft provides a viable option for restoring congruity of the shoulder joint in patients with recurrent anterior glenohumeral instability and a Hill-Sachs lesion.

Abstract

Introduction

Engaging Hill-Sachs lesions (HSLs), termed “off-track” HSLs, pose a significant risk for recurrent anterior shoulder instability. Humeral head reconstruction with fresh osteochondral allograft (OCA) serves as a potential treatment option for anatomic reconstruction. More specifically, talus OCA is a promising graft source due to its high congruency with a dense cartilaginous surface. This study aims to analyze the surface geometry of talus OCA augmentation for the management of shoulder instability with varying sizes of HSLs. We hypothesized that talus OCA augmentation can restore the bone congruency and surface area of a HSL.

Methods

Seven fresh-frozen cadaveric shoulders were tested in this study and the humeral heads skeletonized, and then were digitized using a Romer Arm (SimVITRO, Cleveland, OH). A HSL defect was created by a three-dimensional printed plastic model representing a small-, medium- and large-HSLs by actual patients’ CT-scan. Surface laser scan analysis was performed on seven cadaveric humeral head testing states: (1) Native state, (2) Small HSL, (3) After talus OCA augmentation for small HSL, (4) Medium HSL, (5) After talus OCA augmentation for medium HSL, (6) Large HSL and (7) After talus OCA augmentation for large HSL. The laser scan data was processed using a custom MATLAB (version R2021a, The MathWorks Inc., Natick, MA) script. Surface congruency was calculated as the average absolute error and root mean squared error in the distance between registered points from the non-native specimen to the native specimen. A one-way repeated measures ANOVA was performed to evaluate the effects of the difference in HSL size and associated talus OCA on surface congruency and HSL surface area.

Results

Surface area analysis of the humeral head with the large-(1,469 ± 75 mm2), medium-(1,391 ± 81 mm2), and small-(1,230 ± 54 mm2) HSLs exhibited significantly higher surface areas than the native state (1,007 ± 88 mm2 with p< 0.001 for all sizes). The native state exhibited significantly lower surface area, as compared to after talus OCA augmentation for large HSL (1,235 ± 63 mm2, p< 0.001), but not significantly different after talus OCA augmentation for small- and medium HSLs. Talus OCA augmentation yielded improved surface area and congruency after treatment in small-, medium-, and large-HSLs(p < 0.001).

Conclusion

Talus OCA augmentation restored surface area and congruency across all tested HSLs, and the surface area was best improved with the most common HSLs – small and medium. Talus OCA provides a viable option for restoring congruity of the shoulder joint in patients with recurrent anterior glenohumeral instability and a HSL. Additional work is necessary to assess the overall mechanics and healing in vivo.