Proprioceptive changes measured by histopathological and electrophysiological evaluations after NGF injection of anterior cruciate ligament reconstruction

Dong Zhen, Bing Qiu, Weiguo Wang, Zhirong Yang, Jingwei Wang, Yang Gan, Bing Qiu


Background: Proprioceptive recovery has received an increased amount of attention after undergoing anterior cruciate ligament (ACL) reconstruction. However, ACL reconstruction without rehabilitation training could not significantly improve the reduction and function of the proprioceptor. This study aimed to explore whether nerve growth factor (NGF) could cause proprioceptive changes after ACL reconstruction through histopathological and electrophysiological evaluations.
Methods: A total 28 mature New Zealand white rabbits were used in the study, 24 to develop the model of ACL injury and ACL reconstruction. These included the experimental group (n=12; injected with NGF 20 µg/week at the second month after surgery) and the experimental control group (n=12), and 4 for blank control group. In the 4th, 8th, and 12th months, the changes in ACL nerves were measured by somatosensory evoked potentials (SEPs) and electromyogram (EMG). Furthermore, gold chloride staining was performed to detect the changes in morphology and quantity of the proprioceptors in ACL.
Results: Electrophysiological tests showed that the incubation of SEPs and EMG in both the experimental group and the experimental control group were prolonged, and the amplitude decreased when compared with the blank control group (all, P<0.05). Also, in comparison to the experimental control group, the experimental group injected with NGF had a shorter incubation and higher amplitude (all, P<0.05). Furthermore, histopathology analysis revealed that the number of proprioceptors in the experimental group injected with NGF was significantly increased, and the atypical structure was reduced (all, P<0.05).
Conclusions: The results showed the injection of NGF (injected with 20 µg/week in the second month after surgery) could improve joint function rehabilitation by promoting function and quantity of proprioception after ACL reconstruction.