It is well known that cubital tunnel syndrome frequently occurs in throwing athletes. The cause of cubital tunnel syndrome is considered to be mechanical stimuli on the ulnar nerve in the cubital tunnel.The hypothesis of the present cadaveric study was that the ulnar nerve is subjected to longitudinal strain in the cubital tunnel during the throwing motion.
Four phases of throwing (stance, wind-up, middle cock-up, and early acceleration) were passively simulated in seven fresh-frozen transthoracic cadaveric specimens that were fixed in an upright position to allow free arm movement. In each throwing phase, the elbow was sequentially flexed from 45 degrees to 90 degrees to 120 degrees to maximum flexion. The longitudinal movement of and strain on the ulnar nerve were measured with use of a caliper and a strain gauge at the proximal aspects of both the cubital tunnel and the canal of Guyon.
The movement of the ulnar nerve at the proximal aspect of the cubital tunnel was significantly increased during all throwing phases with increased elbow flexion . An average maximum movement of 12.4 +/- 2.4 mm was recorded during the wind-up phase with maximum elbow flexion. The movement at the proximal aspect of the canal of Guyon was approximately two-thirds of that at the proximal aspect of the cubital tunnel.
The strain on the ulnar nerve at the proximal aspect of the cubital tunnel was significantly increased with elbow flexion in the stance, wind-up, and middle cock-up phases. An average maximum strain of 13.1% +/- 6.1% was recorded during the early acceleration phase with maximum elbow flexion. The strain at the proximal aspect of the canal of Guyon was approximately half of that at the proximal aspect of the cubital tunnel.
In the present study, the maximum strain on the ulnar nerve during the acceleration phase was found to be close to the elastic and circulatory limits of the nerve. (Aoki M, Takasaki H, Muraki T, Uchiyama E, Murakami G, Yamashita T: Strain on the ulnar nerve at the elbow and wrist during throwing motion. Journal of Bone & Joint Surgery - American Volume. 87(11):2508-14, 2005.
This following study was performed to determine the occurrence, incidence, and relevance of the arcade of Struthers as a point of compression of the ulnar nerve at the elbow region. The medial surface of the distal third of the arm was dissected in 60 limbs of frozen nonfixed cadavers, and the region was surveyed for the existence of musculotendinous and fibrous structures resembling an arch. When present, its appearance, extension, distance from the medial humeral epicondyle, and relation with the ulnar nerve were recorded.
A musculotendinous arcade, defined as arcade of Struthers, was identified in 8 limbs (13.5%). The extension of the arcade ranged from 2.5 to 5.0 cm (median 3.75 cm), and the distance between its distal limit and the medial humeral epicondyle ranged from 3 to 10 cm (median 6.82 cm).
No evidence of ulnar nerve compression was found in the specimens where an arcade was identified. Although the use of the term arcade of Struthers seems to be historically incorrect, this relatively rare anatomical structure does exist. Well recognized as a potential secondary site of compression of the ulnar nerve at the elbow in patients submitted to anterior transposition surgery, its importance as a primary site of compression probably has been underestimated.( Siqueira MG, Martins RS The controversial arcade of Struthers: Surgical Neurology. 64 Suppl 1:S1:17-20; discussion S1:20-1, 2005).