Initially, there may be numbness of the small and ulnar fourth finger which may be transient. If the impingement is not corrected, the numbness may become constant and progress to hand weakness. A characteristic resting hand position of "ulnar claw," where the small and ring fingers curl up, occurs late in the disease and is a sign of severe neuropathy. By contrast, in Guyons canal syndrome (distal impingement) motor symptoms and claw hand may be more pronounced, a phenomenon known as the ulnar paradox. Also, the back of the hand will have normal sensation. Diagnosis
The distinct innervation of the hand usually enables diagnosis of an ulnar nerve impingement by symptoms alone. Ulnar nerve damage that causes paralysis to these muscles will result in a characteristic ulnar claw position of the hand at rest. Clinical tests such as the card test for Froments sign, can be easily performed for assessment of ulnar nerve. However, a complete diagnosis should identify the source of the impingement, and radiographic imaging may be necessary to determine or rule-out an underlying cause.Imaging studies, such as ultrasound or MRI, may reveal anatomic abnormalities or masses responsible for the impingement. Additionally, imaging may show secondary signs of nerve damage that further confirm the diagnosis of impingement. Signs of nerve damage include flattening of the nerve, swelling of the nerve proximal to site of injury, abnormal appearance of nerve, or characteristic changes to the muscles innervated by the nerve.
In such cases, closed reduction followed by immobilization in a thumb spica cast and serial radiography may be all that is required for effective treatment. For Bennett fractures where there is between 1 mm and 3 mm of displacement at the trapeziometacarpal joint, closed reduction and percutaneous pin fixation (CRPP) with Kirschner wires is often sufficient to ensure a satisfactory functional outcome. The wires are not employed to connect the two fracture fragments together, but rather to secure the first or second metacarpal to the trapezium. For Bennett fractures where there is more than 3 mm of displacement at the trapeziometacarpal joint, open reduction and internal fixation (ORIF) is typically recommended.Regardless of which approach is employed (nonsurgical, CRPP, or ORIF), immobilization in a cast or thumb spica splint is required for four to six weeks. Prognosis
If intraarticular trapeziometacarpal fractures (such as the Bennett or Rolando fractures) are allowed to heal in a displaced position, significant post-traumatic osteoarthritis of the base of the thumb is virtually assured. Some form of surgical treatment (typically either a CRPP or an ORIF) is nearly always recommended to ensure a satisfactory outcome for these fractures, if there is significant displacement.The long-term outcome after surgical treatment appears to be similar, whether the CRPP or the ORIF approach is used. Specifically, the overall strength of the affected hand is typically diminished, and post-traumatic osteoarthritis tends to develop in almost all cases. The degree of weakness and the severity of osteoarthritis does however appear to correlate with the quality of reduction of the fracture.