Prior to Repair Functional Deficits in Above- and Below-Elbow Ulnar Nerve Injury

Clinical deficits might vary, depending on whether an ulnar nerve lesion is above or below the elbow. Lack of strength and clawing are common manifestations of ulnar nerve paralysis. However, the magnitude of strength deficit relating to different pinch patterns and the rate and range of proximal interphalangeal extension deficits are poorly described.

I prospectively evaluated 14 patients with above-elbow and 16 with below-elbow unrepaired ulnar nerve injuries. The completeness of flexion of the ring and little fingers was tested at the metacarpophalangeal and distal interphalangeal joints. Proximal interphalangeal joint extension lag of the ring and little fingers was assessed by goniometry, and adduction and abduction of the little finger. With dynamometers, I bilaterally evaluated grasp, key pinch, and pinch-to-zoom strength. Hand sensibility was evaluated with monofilaments.

Metacarpophalangeal flexion in the ulnar fingers was absent in all patients, whereas distal interphalangeal joint flexion was preserved in 29 of 30 patients. In above-elbow ulnar nerve injuries, there was no paralysis of the flexor digitorum profundus. One-third of patients exhibited no clawing. There were minimal differences between the rate of clawing and proximal interphalangeal extension lag in above- and below-elbow ulnar nerve lesions, or its occurrence in the ring or little finger. In relation to the normal hand, grasping, key pinch, and pinch-to-zoom decreased by 62%, 51%, and 75% compared with 59%, 61%, and 76% in below- and above-elbow injuries groups, respectively. In both groups, sensory deficits were predominantly over the little finger and ulnar side of the hand.

Minimal differences were observed in clinical deficits after above- and below-elbow ulnar nerve injuries. Hand weakness was the most frequent problem, whereas pinch-to-zoom strength was highly affected.

Diagnostic IV.