The course of recovery of locomotor function over a 10‐week observation period in a rat model of femoral nerve resection and autograft repair

Abstract

Background:A great extent of knowledge on peripheral nerve regeneration has been gathered using the rat sciatic nerve model. The femoral nerve model of the rat offers an interesting alternative, as it lacks disadvantageous features such as automutilation. For the analysis of locomotor behavior in rats after sciatic nerve injury, the CatWalk ™ XT Gait Analysis System is often used. However, lesions of the femoral nerve in the rat have yet remained unstudied with this method. Material and Methods: Ten male Sprague Dawley rats were evaluated with theCatWalk XT to study their gait after a 6-mm resection of the right femoral nerve and reconstruction with an autologous nerve graft. Animals were observed for 10 weeks after surgery.Results: Print Area, Print Length, Swing Speed, and Duty Cycle decreased to a minimum of 40% of baseline 2 weeks after surgery. Swing Time was elevated more than twofold at this time point. However, all these parameters recovered back to >90% of baseline values at 10 weeks after surgery. This degree of functional recovery has not been reported after sciatic nerve resection and autograft repair. Base of support varied minimally postoperatively in contrast to a strong decrement after sciatic nerve resection and repair. Conclusion:We hereby provide a comprehensive in-depth analysis of how to study functional recovery after injury of the femoral nerve in the rat via the CatWalk XT.We place special emphasis on highlighting the differences between the femoral nerve and sciatic nerve injury model in this context. K E Y W O R D SCatWalk XT, femoral nerve, functional recovery, gait analysis, rats, sciatic nerve

Evaluation of Functional Recovery in Rats After Median Nerve Resection and Autograft Repair Using Computerized Gait Analysis

“…The course of BoS following median nerve injury and repair showed no significant alterations with the exception of WPO10, when FP BoS decreased, leading to a significant decrease of the FP/HP BoS ratio. Whereas an increased BoS was reported to account for an unstable gait in rats with spinal cord injury (Hamers et al, 2001 ; Joosten et al, 2004 ; Datto et al, 2016 ), it was shown to strongly decrease in rats with sciatic nerve neurotmesis (Deumens et al, 2007 ) and to show slight fluctuations in rats with femoral nerve neurotmesis (Heinzel et al, 2020b ). In light of the only slight alterations observable in our model, we hypothesize that these changes might also be related to the way the BoS is calculated by the CW software.…”

“…We therefore hypothesize that median nerve injury results in less accentuated changes of proprioception of the affected paw, given the small area of the limb innervated by the median nerve compared to both the femoral or sciatic nerve (Jackson, 1936 ). Changes in the distribution of NSSP, specific sequences of paw placements during locomotion (Cheng et al, 1997 ; Deumens et al, 2014 ), have been observed in rats after both sciatic nerve and femoral resection and are thought to correspond to altered proprioception of the respective limb (Heinzel et al, 2020b ). To maintain balanced gait, rats tend to let the affected limb be preceded by the most distant paw, e.g., LF is preceding RH in case of resection of the right sciatic nerve (Deumens et al, 2007 ).…”

“…This results in amputation of the toes or parts of the paw and in consequence only limited or even impossible functional evaluation (Weber et al, 1993 ). Besides other emerging alternatives to the sciatic nerve model, e.g., the femoral nerve model (Hercher et al, 2019 ; Heinzel et al, 2020b ), the median nerve model is gaining increasing attention within the scientific community (Ronchi et al, 2019 ). In rats, as in humans, the median nerve is one of the main nerves of the brachial plexus, originating from the spinal roots C 5 to Th 1 .…”

“…The method allows for evaluation of a plethora of parameters related to gait, the ones routinely and most assessed in rats with peripheral nerve injury are listed in Table 1 . Some parameters have been shown to be related to pain, although this does not imply that they cannot also be altered by impaired motor or sensory function in general (Vrinten and Hamers, 2003 ; Heinzel et al, 2020b ). Other parameters have been subsumed under the term general parameters of gait or coordination-related parameters of gait.…”

Automated Gait Analysis to Assess Functional Recovery in Rodents with Peripheral Nerve or Spinal Cord Contusion Injury

“…Table 1). The feasibility of AGA to detect changes in gait behavior has been proven in various animal models of peripheral nerve injury (PNI) 21 , such as the sciatic nerve 20 , femoral nerve 22 , and median nerve 23 , 24 . It is also routinely used to assess locomotor function in rats with central nervous injuries, e.g., stroke 25 or spinal cord contusion 26 .…”