Elbow
The influence of proximal ulnar morphology on elbow range of motion

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Background

Physiologic dorsal apex angulation of the proximal ulna is present in 96% of the population. We hypothesize that a correlation exists between the physiologic dorsal ulnar angulation and elbow range of motion (ROM).

Methods

Fifty healthy adults underwent bilateral lateral elbow radiographs in neutral forearm rotation in the following positions: terminal flexion (TF), 90° of flexion, and terminal extension (TE). The proximal ulna dorsal angulation (PUDA), TF, and TE were measured on the digital lateral radiographs by 2 independent observers. ROM was calculated as the difference between TF and TE measurements. Subjects were divided into 2 groups: those with PUDA measurements less than the median and those with PUDA measurements equal to or greater than the median. The relationship between the PUDA and TE, TF, and ROM was evaluated by use of Pearson correlation coefficients.

Results

The mean age of the cohort was 31 ± 9 years, and there were 30 women among the 50 volunteers. The sample of 100 elbow radiographs had a mean TF of 150.8° ± 4.5°, a mean TE (ie, flexion contracture) of 11.5° ± 7.3°, and a mean ROM of 139.3° ± 8.4°. The mean PUDA was 5.2° ± 2.8°. Elbows with a greater PUDA had significantly less TE (r = 0.381, P ≤ .001) and ROM (r = −0.351, P ≤ .001). The group of elbows with a lesser PUDA had better TE (9.4° vs 13.6°, P = .004) and ROM (142.0° vs 136.7°, P = .001) than elbows with a greater PUDA.

Conclusion

The increasing magnitude of the PUDA is associated with decreased maximal elbow extension and global elbow ROM.

Section snippets

Methods

Healthy adult volunteers, who were employees or visitors to a level 1 trauma center, were recruited for this study. The inclusion criteria were as follows: aged between 18 and 50 years and no pre-existing elbow pathology in either upper limb. Pregnant women or women who may become pregnant were excluded. Fifty volunteers were recruited for this study according to the guidelines of Harrison et al12 for the radiologic evaluation of measurements.

Standardized lateral elbow radiographs were taken at

Results

The mean age of the cohort was 31 years (SD, 9). There were 30 women among the 50 participants. The mean PUDA of the 100 elbows was 5.2° (range, −0.2° to 11.8°; SD, 2.8°). The radiographic measurements for the entire cohort were as follows: mean TF of 150.8° (range, 140.4° to 159.8°; SD, 4.5°), mean TE of 11.5° (range, −5.5° to 28.4°; SD, 7.3°), and mean ROM of 139.3° (range, 116.0° to 158.4°; SD, 8.4°).

The correlation coefficients between the PUDA and TE, TF, and ROM are presented in Table I.

Discussion

The PUDA was related to elbow extension and global elbow ROM in normal adult subjects. Interestingly, terminal elbow flexion was not affected by changes in the magnitude of the PUDA. It is possible that additional flexion was not seen in the high PUDA group because, unlike extension, TF is limited by soft tissues. To our knowledge, an association between morphologic variations in ulnar anatomy and elbow ROM has not previously been described. The etiology of the variability in the magnitude of

Conclusion

The PUDA was found to be related to the maximal elbow extension and, consequently, ROM. When one is assessing elbow motion, especially after contracture release, knowledge of the contribution of the PUDA to ROM is important. For example, patients with a larger-magnitude ulnar angulation consequently will have less elbow extension.

Disclaimer

The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.

References (20)

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Institutional review board: Approvals were obtained from the Institutional Review Boards of the ethical committees of Hôpital du Sacré-Cœur (CER 2010-05-43) and École de Technologie Supérieure.

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