Basic ScienceThe effects of arm elevation on the 3-dimensional acromiohumeral distance: a biplane fluoroscopy study with normative data
Section snippets
Subjects
For this descriptive laboratory study, 8 healthy male subjects (mean age, 30 ± 7 years; mean height, 1.84 ± 0.05 m; mean weight, 90 ± 9 kg) were recruited. Before participation, all participants signed an informed consent form. Four right shoulders (all dominant side) and four left shoulders (one dominant and three nondominant) were used for analysis. To rule out shoulder pathology, a medical history was taken and full clinical examination of the shoulders was performed. The data collection
Results
The mean AHD as a function of arm elevation angle for the 2 exercises is shown in Figure 2. The AHD was significantly affected by the plane of elevation (P = .009) and by the elevation angle and decreased with arm elevation until a minimum occurred, after which the AHD increased (P < .0001). This pattern was consistent among the subjects and exercises. The AHD was significantly higher for scaption compared with forward flexion for arm elevation angles of 120° and 130°. The minimum AHD measured
Discussion
We found that the minimum AHD occurred at approximately 90° of arm elevation with minimum distance points at the undersurface of the acromion and the proximal humeral shaft. The minimum distance point was located within the footprint of the supraspinatus on the greater tuberosity between 34° and 72° of scaption and between 36° and 65° of forward elevation. We confirmed our hypothesis that the AHD narrowed during elevation exercises and that the location of the AHD measurement between the
Conclusion
In vivo normative AHDs were measured in 8 healthy male subjects by biplane fluoroscopy during 2 arm elevation exercises to understand how arm position influenced AHD and to provide reference measures for future studies of shoulder pathology. The minimum AHD measured was 2.6 ± 0.8 mm during scaption and 1.8 ± 1.2 mm during forward flexion at elevation angles of 83° ± 13° and 97° ± 23°, respectively. In addition, the minimum distance points between the acromion and the proximal humerus were
Acknowledgment
The authors thank Robert F. LaPrade, MD, PhD, for his invaluable input to the manuscript. In addition, they thank Michael R. Torry and Kevin B. Shelburne for their assistance during the conduct of this study. Also, they thank J.D. Pault, J.P. Brunkhorst, Tyler Anstett, and Nils H. Horn for their support in the processing of the biplane fluoroscopy data. Finally, they thank Arthrex for funding the Research Fellow position at the Steadman Philippon Research Institute held by Olivier A.J. van der
Disclaimer
This research was supported in part by the Gumbo Foundation and by the Steadman Philippon Research Institute, which is a 501(c)(3) nonprofit institution supported financially by private donations and corporate support from the following entities: Smith & Nephew Endoscopy, Arthrex, Siemens Medical Solutions, OrthoRehab, ConMed Linvatec, Ossur Americas, SBi, Opedix, and Alignmed.
Peter J. Millett is a consultant for Arthrex and has stock options in Game Ready.
Olivier A.J. van der Meijden’s
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This study was approved by the Institutional Review Board of Vail Valley Medical Center (protocol No. 2006-04).