Biomechanical study of Essex-Lopresti injury

Abstract

Objective To study the biomechanical mechanism of Essex-Lopresti injury, and provide biomechanical basis for diagnosis and treatment of Essex-Lopresti injury. Methods Twelve fresh frozen adult upper limbs were addressed. Firstly, 12 samples (complete state group) were loaded 100 N of a compressive force lasting 30 seconds in pronation, supination and neutral position on the mechanical testing machine. Secondly, 12 specimens were randomly divided into 2 groups. In the group named resection of radial head, the radial head was removed and interosseous membrane (IOM)was intact. In the group named the section of interosseous membrane, IOM was cut off. Finally, the radial head were removed and IOM was cut off in all specimens. The group was named as resection of radial head and IOM. Each sample was tested according to the method as described. Results The forearm rotation or single excision of the IOM had no effect on radial longitudinal displacement. Simple radial head excision or resection of the IOM and the radial head increased the vertical displacement of the radius. The radial stiffness had a gradual decline in forearm supination, neutral position and pronation. Simple excision IOM has no effect on the radial stiffness. The radial stiffness had decreased under the condition of excision of radial head or resection of the IOM and the radial head. Conclusion These in vitro measurements validate that the radial head fracture with IOM injury may be important reason for complications of the Essex-Lopresti injury. Radial head fracture play a key role for Essex-Lopresti injury and the injury of IOM is secondary cause. IOM is responsible for maintaining the vertical stability of the forearm after radial head resection. Key words: Forearm injuries; Radius fractures; Biomechanics