OBJECTIVE: To study the morphological changes of the rat claw inner skeletal muscle after ulnar nerve injury at different sections and different recovery times. METHODS: Forty-two adult male Sprague-Dawley rats were selected and placed randomly in seven groups. After establishing model of injury and repair of claw inner skeletal muscle by cutting off the ulnar nerve, the muscle wet weight, cross section area of myocytes, and collagen fibers were measured. RESULTS: Claw inner skeletal muscle atrophy was significantly less in experiment groups compared with the control groups after ulnar nerve injuries. The functional recovery was better in the early repair groups than the late repair group. Collagen fibers increased slowly in earlier stage, but more significantly in late stage. The muscle atrophy was similar in wrist and elbow after ulnar nerve injury during the same recovery period. CONCLUSION The function can recover completely or partly in early repair groups, but not quite effective in late stage. The increase of collagen fiber is one of the reasons to undermine the recovery effect of damaged ulnar nerve. There is no obvious difference of effect on the morphological changes of the rat claw inner skeletal muscle no matter the ulnar nerve is injured at wrist or elbow.
Animals ; Male ; Muscle, Skeletal/pathology* ; Muscular Atrophy/prevention & control* ; Nerve Regeneration/physiology* ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Plastic Surgery Procedures ; Ulnar Nerve/surgery*

BACKGROUND: The aim of this study was to evaluate the contribution of the proximal nerve stump, in end-to-side nerve repair, to functional recovery, by modifying the classic end-to-side neurorrhaphy and suturing the proximal nerve stump to a donor nerve in a rat model of a severed median nerve. METHODS: Three experimental groups were studied: a modified end-to-side neurorrhaphy with suturing of the proximal nerve stump (double end-to-side neurorrhaphy, Group I), a classic end-to-side neurorrhaphy (Group II) and a control group without neurorrhaphy (Group III). Twenty weeks after surgery, grasping testing, muscle contractility testing, and histological studies were performed. RESULTS: The grasping strength, muscle contraction force and nerve fiber count were significantly higher in group I than in group II, and there was no evidence of nerve recovery in group III. CONCLUSIONS: The contribution from the proximal nerve stump in double end-to-side nerve repair might improve axonal sprouting from the donor nerve and help achieve a better functional recovery in an end-to-side coaptation model.
Anastomosis, Surgical/methods ; Animals ; Axons/pathology ; Forelimb ; Hand Strength ; Male ; Median Nerve/pathology/*surgery ; Muscle Contraction ; Muscle, Skeletal/physiopathology ; Nerve Regeneration ; Nerve Transfer/*methods ; Rats ; Rats, Sprague-Dawley ; Recovery of Function ; Ulnar Nerve/pathology/*surgery