2017 ISAKOS Biennial Congress ePoster #2101

 

Anatomical Investigation of the Acromion Shape, Thickness and Bone Mineral Density to Support Treatment of Acromioclavicular Joint Instability

Andreas Voss, MD, Regensburg, BY GERMANY
Felix Dyrna, MD, M√ľnster GERMANY
Andrea E. Achtnich, MD, Munich GERMANY
Alexander Hoberman, BS, Farmington, CT UNITED STATES
Andreas B. Imhoff, MD, Prof., Munich, Bavaria GERMANY
Augustus D. Mazzocca, MS, MD, Farmington, CT UNITED STATES
Knut Beitzel, MD, MA, Cologne GERMANY

Department of Orthopaedic Surgery, University of Connecticut, Farmington, CT, UNITED STATES

FDA Status Not Applicable

Summary

The current study adds a detailed knowledge of the best areas for the placement of bone tunnels or the fixation of grafts. The posterior-medial acromion close to the AC-joint reveled the highest BMD with an increasing density from lateral to medial. The results can be directly transferred to improve the surgical treatment options.

Abstract

Introduction

Recent techniques for acromioclavicular (AC) joint reconstruction focus on additional AC cerclage to coracoclavicular (CC)-reconstructions. Due to the specific slim bone morphology at the acromion, there are concerns regarding these additional bone tunnels, as they may predispose to fracture and break out. The purpose of this study was to investigate anatomic properties of the acromion which may help improve surgical techniques directed at injuries to the AC joint. It was hypothesized that via measurements of thickness and density that points of increased strength and support could be identified on the acromion.

Methods

Eighty-five fresh frozen cadaveric shoulders were used for this study. A standardized 3D-net was developed and thicknesses of the acromion were taken from defined points using a certified caliper. To define the acromial arch, the angle and radius of curvature between the antero-lateral, the highest point of the acromial arch and the postero-lateral aspect of the acromion were measured. Additional bone mineral density (BMD) evaluation was performed on 43 specimens in an anterio-posterior and latero-medial direction using 5mm slices with a maximum of 10 and 6 slices respectively.

Results

Mean specimen age was 62.7 years (55 female, and 30 male). There was no statistical signifi-cance between male (62.4±8.7) and female (62.9±9.2) regarding age (p=0.797). Thickness of acromion points of interest were ranging from 3.5 mm to 24.3 mm. Mean radius of curvature of acromial arch for female was 54.6±20.7 mm and 66.05±23.6 mm for male (p=0.019). The mean angle for female speci-mens was 20.9±8.9° and 25.7±13.3° for male (p=0.047). The latero-medial measurements showed sig-nificant difference between the region of interest (ROI): 1 and 4,5,6 (p=0.001, p=0.001, p=0.001), 2 and 4,5,6 (p=0.007, p=0.001, p=0.001), 3 and 5,6 (p=0.001, p=0.001), 4 and 5,6 (p=0.010, p=0.001). Ante-rio-posterior measurements showed significant difference between the ROI: 1 and 8 (p=0.031).

Conclusion

The posterior-medial acromion close to the AC-joint reveled the highest BMD with an in-creasing density from lateral to medial. In combination with thickness measurements this region would support additional anatomical fixation of the AC-joint using bone tunnels if necessary