Functional assessment of misdirected axon growth after nerve repair in the rat

Age, late repair, loss of nerve tissue, tension, and other factors are now known to influence axon regeneration and the quality of recovery after nerve repair. Many of the factors cannot be controlled by surgery. However, a few important ones depend on surgical technique, and some could be minimized, e.g., suture with tension, scarring due to foreign material, and misdirected axon growth. In this study, the authors tried to assess the functional consequences of misdirected axon growth in the sciatic nerve of the rat. They used a strainless coaptation nerve-repair technique with bioabsorbable plate support (polylactic acid), permitting them to study only the consequences of misdirected axon growth, without tension or suture in the area of nerve repair. Sixty rats were divided into three groups. In Group 1, 20 sciatic nerves were repaired without rotation of the distal nerve stump. In Group 2, 20 sciatic nerves were repaired with a 90-degree rotation of the distal nerve stump. In Group 3, 20 sciatic nerves were repaired with a 180-degree rotation of the distal nerve stump. Functional analyses were performed with the sciatic functional index. The results showed the poor consequences of incorrect nerve-end alignment in nerve repair (p < 0.05). Nerve repair with bioabsorbable plate support is known to allow good stump coaptation, without tension and without foreign material. The authors suggest an adaptation or modification of this technique, which might minimize misdirected axon growth, one of the factors whose effects can be mitigated by surgical technique.