acute traumatic subluxation of the ulnar nerve at the cubital tunnel is rare or under - reported a 31 year old asian man presented with severe , radiating pain from the elbow to forearm , following a fall on his outstretched hand . our case report summarizes the presentation , management and pathomechanism of a rare clinical entity . ulnar nerve , being in close proximity to the elbow joint is predisposed to trauma and entrapment neuropathy where it courses through the cubital tunnel . subluxation or dislocation of the nerve at this site could occur as a result of trauma or variations in the anatomical structures posterior to elbow joint . while recurrent or chronic subluxation of ulnar nerve has been commonly reported a 31 year old , obese businessman presented to the emergency with complaints of severe pain in the left elbow , radiating to the forearm . his left foot turned inwards and he sustained a fall onto his left hand with the elbow bent . immediately after the fall , he experienced an electric shock like sensation which radiated along the inner aspect of the forearm . he experienced severe radiating pain along ulnar nerve distribution whenever the elbow was flexed beyond 80 degrees . orthogonal views of the elbow did not reveal any fracture or abnormality of medial epicondyle . dynamic ultrasound of the elbow revealed subluxation of the ulnar nerve as evidenced by increased distance between the floor of the cubital tunnel and the nerve , in comparison to the opposite elbow . the nerve was found to subluxate from the cubital tunnel with elbow flexion beyond 90 degrees . 1.(ultrasound image of posterior elbow ) the displacement of ulnar nerve ( white arrow ) in relation to medial epicondyle has been shown with the elbow in more than 90o flexion ( left ) and in extension ( right ) in the ultrasound image . the arm was rested in a broad arm sling for three weeks in 45 degrees flexion , a position in which he had no pain . he also had a grade i / ii lateral collateral ligament sprain of the ipsilateral ankle which was treated by below knee cast . at three weeks follow up , the patient had no pain but a fixed flexion deformity of 15 degrees at the elbow . he was advised active range of motion exercises and the sling was discontinued . at final follow up , one year after the injury , patient was asymptomatic and had full range of pain free motion at the elbow and with no neurological deficit in the upper limb . ulnar nerve subluxation was first reported by blattmann in 1851   knowledge of the pathoanatomy and dynamic relationship of the ulnar nerve in cubital tunnel is crucial in understanding this pathology . at the elbow , the ulnar nerve lies in the cubital tunnel ; the posterior wall of which is formed proximally by the fascial aponeurosis between the two heads of flexor carpi ulnaris and distally by its muscle belly . childress , in his study of 1000 patients found ulnar neuritis in 21% of those with ulnar nerve subluxation . recurrent ulnar nerve subluxation has been associated with laxity of the cubital tunnel roof , congenital hypoplasia of medial epicondyle , variations in muscular anatomy or post - traumatic changes [ 3 - 8 ] . richard mj et al found various muscular anomalies in his retrospective review of 18 elbows . dellon noted large medial head of triceps extending into the floor of cubital tunnel in 28% of cadavers , 77% of which had demonstrable subluxation of ulnar nerve . friction neuritis explains ulnar nerve symptoms in recurrent ulnar nerve subluxation . however acute traumatic ulnar nerve subluxation still remains a poorly understood clinical entity due to scarcity of data . there are a very few reports worldwide and a single report in english literature on acute traumatic subluxation of ulnar nerve . we propose a possible explanation of the mechanism of traumatic ulnar nerve subluxation in our patient . . a sudden upward thrust on the flexed elbow will further stress this ligament and cause tear . this renders the ulnar nerve susceptible to subluxation or dislocation . with elbow flexion beyond 90 degrees , the strain on ulnar nerve increases and it tends to translate anteriorly over the medial epicondyle as shown in fig . [ 11 , 12 ] . in the absence of an intact osborne s ligament , we believe that splinting the elbow for three weeks , in our patient lead to healing of osborne s ligament which thereby prevented nerve subluxation thereafter . a ) the integrity of the roof of cubital fossa is shown with elbow in extension ( left ) . b ) following a fall on the flexed elbow the roof of the cubital fossa is disrupted ( right ) . ultrasound is a useful tool in diagnosis of ulnar nerve subluxation as it detects real time translation of the nerve with changing elbow flexion . though the ulnar nerve was found subluxated in our patient , tear in osborne s ligament could nt be well visualized . an mri of the elbow can detect tear in the osborne s ligament and also assess integrity of medial collateral ligament at the same time . there is no consensus or evidence for the best treatment for chronic or recurrent ulnar nerve subluxation and data for traumatic nerve subluxation is scarce . patients with persistent symptoms or painful snapping or those refractory to conservative line of management could be considered for surgery . various modes of treatment have been suggested in the management of recurrent ulnar nerve subluxation . few authors have suggested conservative line of management in the form of splinting or physiotherapy initially followed by surgical treatment if the former fails . splinting the elbow in 30 - 45 degrees of flexion our patient was treated by splinting in 50 degrees flexion followed by range of motion exercises . we believe that splinting followed by physiotherapy restores the integrity of the roof of cubital tunnel . diagnosis can be confirmed by dynamic ultrasonography . in the absence of neurological deficit , it can be managed conservatively by splinting the elbow in mid - flexion . electric shock like pain in the elbow , following trauma which aggravates with flexion should suggest possibility of acute ulnar nerve subluxation . failure to recognize this injury and avoiding splinting may lead to recurrent subluxation of the nerve .
introduction : acute traumatic subluxation of the ulnar nerve at the cubital tunnel is rare or under - reportedcase report : a 31 year old asian man presented with severe , radiating pain from the elbow to forearm , following a fall on his outstretched hand 
 . he had swelling and severe tenderness at the posteromedial aspect of the elbow . 
 pain aggravated with elbow flexion beyond 80 degrees.there was no neurological deficit . 
 dynamic ultrasound demonstrated subluxation of ulnar nerve with elbow flexion . 
 broad arm sling immobilization was given for three weeks . at final follow up 
 , he was asymptomatic with full range of pain free motion at the elbow.conclusion:our case report summarizes the presentation , management and pathomechanism of a rare clinical entity .