The Elbow

Literature

Clin Orthop 1975 May;(108):168-73

Recurrent ulnar-nerve dislocation at the elbow.

Childress HM

Recurring luxation of the ulnar nerve at the elbow is not uncommon (16.2%), occurring about equally in young and old, male and female, athletes and non-athletes but the greater mobility is usually at the dominant arm. The probable cause of such dislocation is congenital laxity of supporting ligaments. Being more vulnerable to injury than normally-positioned nerves, however, complicating neuritis can does occur. Subluxating nerves which stop on the tip of the medial humeral epicondyle upon 90 degrees or more of flexion at the elbow are more subject to direct trauma than completely displaced neural structures which cross the epicondyle upon elbow flexion. The latter may develop friction neuritis which occurs most frequently in industrial workers and occasionally requires surgical transfer. Deep intramuscular implantation, with or without neurolysis, is definetely superior to subcutaneous placement of the affected nerve. In this report are described chemically-induced ulnar neuritis from cortisone injections about the medial humeral epicondyle; pressure ulnar neuritis in patients with enforced bed rest and from improper positioning on operating table with permanent neural deficit and the relationship of such hypermobile ulnar nerves to extension-flexion (whiplash) trauma to the neck. It is emphasized that most of these complications could have been avoided had the patient and his physician known that such anomalies were present. Of particular importance is the avoidance of pressure to the medial aspect of a flexed elbow in surgical patients under general anesthesia. The unrelated co-existence of intermittently-symptomatic hypermobile ulnar nerves and extension-flexion neck trauma may occur. Recognition of isolated unlar neuritis in these patients is definitely important from the diagnostic, treatment and medical-legal aspects of such cervical spine injuries.

South Med J 1977 Jan;70(1):36-40

Ulnar nerve instability: ulnar nerve injury due to elbow flexion.

Lazaro L 3d

The term "ulnar nerve instability" describes the chronic conditions of subluxation and relocation of the ulnar nerve at the elbow with flexion and extension of the elbow, respectively. This condition is more common than generally thought. Recurrent subluxation of the nerve at the elbow results in a tractional and frictional neuritis. The nerve is vulnerable to trauma in its subluxed position, lying superficially on the medial humeral epicondyle. In certain cases of ulnar nerve instability associated with a tight overlying band bridging the heads of origin of the flexor carpi ulnaris, nerve injury can occur with flexion of the elbow. Thus, internal as well as external compressive factors as a cause of ulnar nerve neuropathy must be considered. Described is an elbow flexion test helpful in the diagnosis and prognosis of cases of ulnar nerve instability associated with the tight overlying band.

J Hand Surg [Am] 1998 Nov;23(6):992-7

Ulnar nerve strains at the elbow.

Toby EB, Hanesworth D

Department of Orthopedic Surgery, The University of Kansas Medical Center, Kansas City 66160, USA.

Twenty unembalmed intact cadavers had strain measurements taken of the ulnar nerve at 5 positions around the elbow and at varying degrees of elbow flexion. A microstrain gauge was implanted directly into the nerve through a superficial incision. Maximum strains in the ulnar nerve occurred at maximum elbow flexion and directly behind the medial epicondyle; meaningfully less strain was seen at lesser degrees of flexion and positions distal and proximal to the epicondyle. A wide range of maximal strains (0% to 14%) was found. Twenty-five percent of the ulnar nerves showed strains of greater than 10% with maximum elbow flexion behind the medial epicondyle. Cubital tunnel syndrome may be at least in part a traction neuropathy.

Clin Orthop 1981 Nov-Dec;(161):270-4

Recurrent dislocation of the elbow accompanied by ulnar neuropathy: a case report and review of the literature.

Malkawi H

Recurrent dislocation of the elbow with paradoxical dislocation of the ulnar nerve complicated by neuropathy may occur from avulsion of the lateral epicondyle and laxity of the collateral ligaments. In a 22-year-old man, the injury was successfully treated by plication of the collateral ligaments. The nerve dislocation was treated by anterior transposition. The result was satisfactory except for persistent atrophy of the ulnar innervated muscles.