[Experimental study on three repairing methods for femoral nerve injury after ligation in rats]

To investigate the effects of 3 methods (suture removal, suture removal with epineurium neurolysis, and ligated femoral nerve resection with end-end suture) in repairing femoral nerve injury after ligation in different periods so as to provide a reference for clinical use of repairing iatrogenic ligation injury of the peripheral nerve.

A total of 120 adult female Sprague Dawley rats, weighing (200 +/- 20) g, were used to prepare the animal models of left femoral nerve ligation, and were divided into groups A (n=40), B (n=40), and C (n=40) according different repairing methods. At immediate, 1, 3, and 5 months (10 rats each time point) after ligation, suture removal was performed in group A, suture removal with epineurium neurolysis in group B, and ligated femoral nerve resection with end-end suture in group C. At 3 months after operation, the foot-base angle (FBA) and the heels-tail angle (HTA), action potential and conduction velocity of femoral nerve, and wet weight of quadriceps femoris muscle (QFM) were measured; the samples of quadriceps femoris and femoral nerve were harvested for histological observation, muscle fiber count, and nerve fiber passing rate measuring.

The FBA in group A was significant smaller than that in group C at immediate, 1, 3, and 5 months (P < 0.05), but there was no significant difference between groups A and B (P > 0.05). The HTA in group A was significantly smaller than that in group C at immediate, 1, 3, and 5 months (P < 0.05), and the THA in group B was significantly smaller than that in group C at 1, 3, and 5 months (P < 0.05). The wet weight of QFM in group B was significantly higher than that in group C at immediate, 3, and 5 months (P < 0.05), and the wet weight of QFM in group A was significantly higher than that in group C at immediate and 3 months (P < 0.05), but no significant difference was found between groups A and B at immediate, 1, and 3 months (P > 0.05). There was significant difference in the action potential of femoral nerve between group A and groups B and C at immediate and 1 month (P < 0.05), but there was no significant difference between other groups at 3 and 5 months (P > 0.05) except between groups A and C at 5 months (P < 0.05). The conduction velocity of femoral nerve in group A was significantly faster than that in group C at immediate, 1, and 5 months (P < 0.05), and it was significantly faster in group A than in group B at immediate and 1 month (P < 0.05), but no significant difference was found between groups A and B at 3 and 5 months (P > 0.05), between groups B and C at other time points (P > 0.05) except at immediate (P < 0.05). The count of muscle fibre of the quadriceps femoris was significantly more in groups A and B than in group C at immediate (P < 0.05); it was significantly more in group A than in group B at 5 months (P < 0.05). The passing rate of the femoral nerve fiber was significantly higher in group A than in groups B and C at 3 months (P < 0.05), but no significant difference was found between the other groups (P > 0.05).

After femoral nerve ligation, suture removal method has the best effect at early term, the next is epineurium neurolysis method, and the worst is the ligation femoral nerve resection with end-end suture repair.