Associations Between External Forearm Dimensions and Internal Ulnar Nerve Spaces at the Elbow

Abstract

Ulnar nerve injury is frequently seen in athletes such as golfers, baseball pitchers, tennis players and weightlifters, typically in the epicondylar groove or cubital tunnel areas, where it may be subjected to compression, traction and friction during certain rapid sports movements. A relationship between the dimensions of some visually easy‐to‐discern external structures of the forearm, and selected internal elbow structures that the ulnar nerve passes through, might help to predict which sportspersons may be at greater risk for ulnar nerve entrapment, with smaller spaces expected to involve greater risk. Two conspicuous external features are the distance between the olecranon of the ulna (OL) and the medial epicondyle of the humerus (ME); and forearm length measured from the ME to the pisiform carpal bone (PI). It was hypothesized that a positive correlation would exist between either one, or both of, OL‐ME (medial forearm width) and ME‐PI (forearm length); and some or all of: ulnar nerve thickness, inner epicondylar space, OL‐ME line to Osborne ligament, and OL‐ME line to the point of entry of the ulnar nerve into the flexor carpi ulnaris muscle, between its humeral and ulnar heads. Twenty cadavers, ten male and ten female (40 forearms) were measured for the above dimensions, using digital calipers and tape. Forearms were maintained at 30° flexion (measured with a digital goniometer). The most prominent part of the crest of each of ME, OL and PI was used, and the average of three measurements was taken for each variable. A Spearman's correlation (SPSS ver. 24), used for non‐normally distributed data, showed that the inner width of the epicondylar groove was significantly related to the external OL to ME distance (r = .403, p = .01) and to the thickness of the ulnar nerve at the OL‐ME line (r = .32, p = .047). In addition, the distance between ME and PI was significantly correlated with the external OL to ME distance (r = .62, p < .001). It may be concluded that the distance between the OL and the ME, as well as the length of the forearm, might be good indicators of the likely internal space that the ulnar nerve is contained within at the OL‐ME line, as well as of the thickness of the ulnar nerve at that line.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.