Effect of elbow flexion angles on stress distribution of the proximal ulnar and radius bones under a vertical load: measurement using resistance strain gauges.

Zhi-Tao Rao,Bing Li,Ning Ma,Feng Yuan

doi:10.1186/s13018-014-0060-0

Zhi-Tao Rao, Bing Li + Show 2 more

Open Access

https://doi.org/10.1186/s13018-014-0060-0

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Abstract

ObjectivesThis study aimed to explore the surface stress at the proximal ends of the ulna and radius at different elbow flexion angles using the resistance strain method.MethodsEight fresh adult cadaveric elbows were tested. The forearms were fixed in a neutral position. Axial load increment experiments were conducted at four different elbow flexion angles (0°, 15°, 30°, and 45°). Surface stain was measured at six sites (tip, middle, and base of the coronoid process; back ulnar notch; olecranon; and anterolateral margin of the radial head).ResultsWith the exception of the ulnar olecranon, the load-stress curves at each measurement site showed an approximately linear relationship under the four working conditions studied. At a vertical load of 500 N, the greatest stress occurred at the middle of the coronoid process when the elbow flexion angles were 0° and 15°. When the flexion angles were 30° and 45°, the greatest stress occurred at the base of the coronoid process. The stress on the radial head was higher than those at the measurement sites of the proximal end of the ulna.ConclusionThe resistance strain method for measuring elbow joint surface stress benefits biomechanics research on the elbow joint. Elbow joint surface stress distributions vary according to different elbow flexion angles.

Highlights

The elbow joint belongs to a composite joint composed of the humeroulnar joint, humeroradial joint, and proximal radioulnar joint encapsulated by a joint capsule [1,2,3]
Microstrain of the elbow at different flexion angles No frisket slippage, specimen fractures, or elbow joint dislocations occurred during the experiment
The electric measurements under different working conditions showed that under a vertical load alone, the strain values at the measurement sites of the coronoid process and radial head were negative, suggesting compressive stress

Summary

Introduction

The elbow joint belongs to a composite joint composed of the humeroulnar joint, humeroradial joint, and proximal radioulnar joint encapsulated by a joint capsule [1,2,3]. The different injury types are generally correlated with the flexion and extension positions of the elbow as. No experimental measurement has yet quantitatively analyzed the bone surface stress of the elbow. No study has explored the variation trends of the surface stress at different degrees of flexion. Understanding the change in trends of stress with flexion angles may help clinicians comprehend the pathological mechanisms of special elbow injury types and develop appropriate surgical procedures and proper postoperative rehabilitation strategies. The surface load stress distributions of the ulna and radius were measured at different elbow flexion angles under a vertical load using the resistance strain measurement technique. The correlation between elbow flexion angles and injury types was explored

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