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Ulnar nerve injury after a comminuted fracture of the humeral shaft from a high-velocity accident: a case report
© Pathak et al.; licensee BioMed Central Ltd. 2012
Received: 28 December 2011
Accepted: 27 April 2012
Published: 10 July 2012
Injury to the ulnar nerve following humerus shaft fracture is a very rare entity because the ulnar nerve is well protected from the bone by muscle and soft tissue, and thus remains unaffected in these fractures. We report what is, to the best of our knowledge, the first case of ulnar nerve injury due to a comminuted humeral shaft fracture. The injury manifested and was diagnosed the day after a high-velocity accident. The paucity of related literature and the necessity for early diagnosis and subsequent treatment of such injuries in high-velocity accidents urged us to document this case.
A 30-year-old Indian man presented to our Emergency Department after a road traffic accident. Our patient complained of right arm pain and the inability to move his extremity. The following morning he developed clawing. Nerve conduction studies on the peripheral nerves of his arm in addition to an X-ray confirmed the diagnosis of a possible injury to the ulnar nerve. Our patient was taken to our Operating Room for surgery, during which a fragment of bone was found abutting the ulnar nerve after penetrating his triceps. This fragment of bone was replaced and the fracture was reduced by open reduction and internal fixation using a dynamic compression plate and screws. Postoperatively, our patient received physical therapy and was discharged two weeks after surgery with no neurological deficit.
This case emphasizes the urgency and importance of careful neurological examination of all the peripheral nerves supplying the arm in patients with a fracture of the shaft of the humerus. In the setting of injury to the arm in high-velocity accidents, a differential diagnosis of ulnar nerve injury should always be considered.
A fracture of the shaft of the humerus constitutes 3% to 5% of all fractures [1, 2]. Radial nerve injuries are the most frequent nerve lesion associated with fractures of the shaft , with a reported incidence of radial nerve damage in almost 11.2% of cases [4–6]. Injury to the ulnar nerve after humerus shaft fractures is a very rare entity as the ulnar nerve is well protected from the bone by muscle and soft tissue, and thus remains unaffected in these fractures . To the best knowledge of the authors, there has only been one case documented in the English medical literature of transection of the ulnar nerve after a fracture of the shaft of the humerus, which was explored four months after the injury. Moreover, no cases of ulnar nerve injury have been described that manifested immediately after a high velocity trauma accident. We report what we believe to be the first case of ulnar nerve injury due to a comminuted humerus shaft fracture, which manifested and was diagnosed the day after a road traffic accident. The paucity of literature and the necessity for early diagnosis and subsequent treatment of such injuries in high-velocity accidents urged us to document this case.
Postoperatively, the tingling and numbness of the little and ring finger gradually subsided and our patient received regular physiotherapy and was discharged two weeks after surgery. Our patient was advised to come regularly for follow-up every three months for a period of one year. Our patient first came for a follow-up appointment four months after discharge and told the attending surgeon about the recovery of the normal functioning of his right hand 14 weeks after surgery; confirming it to have been ulnar neuropraxia.
Humerus shaft fractures usually occur during high velocity trauma with the radial nerve being the most commonly injured [4–6]. In 1998, Stahl et al. reported a case of ulnar nerve palsy after a spiral fracture of the humerus shaft, which was supposedly the first case of its kind . In our case, the ulnar nerve injury was due to the abutment of a fragment of the comminuted fractured humerus, in contrast to the case reported by Stahl . In our patient, the symptoms of ulnar nerve injury manifested and were detected immediately the day after the accident. A fragment of the bone from the fracture of the humerus shaft was found to be the cause of the ulnar nerve injury. The nerve was pushed against the displaced bony fragment, which led to the neurological deficit on his right side. The abrupt stretching of the ulnar nerve by the forcible separation of the bone ends is implicated to be the cause of ulnar nerve injury in a fracture of the shaft of the humerus . After the detection of the clinical manifestation and the subsequent confirmation on the nerve conduction studies, our patient was sent for surgery, which aimed to explore and reposition the bony fragment and fixate the fractured humerus so that the nerve was not further irritated by the bony fragment.
In 1990, Uchida and Sugioka  reported ulnar nerve palsy in six patients with a cubitus varus deformity seven years after supracondylar fractures of the humerus. Ulnar nerve palsy after percutaneous cross-pinning of supracondylar fractures  and after trampoline injuries  have also been reported but, to the best knowledge of the authors, this is the first case reported in the literature which documents a case of ulnar nerve injury due to comminuted fracture of the humerus shaft.
This case emphasizes the urgency and importance of careful neurological examination of all the peripheral nerves supplying the arm in patients with a fracture of the shaft of the humerus. Similar cases occurring in other parts of the world should be documented as it would help promote the dictum of careful peripheral nerve examination and subsequent electrodiagnostic studies in such patients. In the setting of injury to the arm in high-velocity accidents, a differential diagnosis of ulnar nerve injury should always be considered.
Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
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