J Reconstr Microsurg 2006; 22 - A036
DOI: 10.1055/s-2006-949706

2-D Digital Video Ankle Motion Analysis as Evaluation Method for Functional Recovery in the Rat Sciatic Nerve Model

Godard C.W De Ruiter 1, 2, Robert J Spinner 1, 2, Bradford L Currier 1, 2, Anthony Koch 1, 2, Martijn J.A Malessy 1, 2, Michael J Yaszemski 1, 2, Kenton R Kaufman 1, 2, Anthony J Windebank 1, 2
  • 1Leiden University Medical Center, Rochester, Minnesota, USA
  • 2Mayo Clinic, Rochester, Minnesota, USA

Currently, the most commonly used method to evaluate functional results in the rat sciatic nerve model is the sciatic function index (SFI). This method has several limitations, such as immeasurable footprints due to contractures and autotomy. In addition, functional results measured for the SFI often do not correlate with the results of other evaluation methods such as nerve morphometry and electrophysiology. The SFI also fails to distinguish between results for different nerve repair techniques.

The authors therefore developed a new method to analyze functional results using 2-D digital video motion analysis. Motion analysis is increasingly used in patients with neurological deficits. Recent advances in technology have now made it possible to also use this technique in animal research. In this study, the ankle motion in rats was analyzed for the maximum angles of plantar and dorsiflexion after sham operation, and sciatic, tibial, and peroneal nerve crush injuries. Rats were filmed in a transparent runway and automatically tracked for the change in ankle angle from markers placed on the leg of the rat. Results were compared to the scores for the SFI.

Results in normal animals showed that the maximum angle of plantar flexion (6.16° ± 0.09°) is reached at the end of stance phase and the maximum angle of dorsiflexion (49.11° ± 5.20°) during mid-swing. The maximum angle of plantar flexion decreased, compared to the angle for sham-operated animals (4.03° ± 5.15°) after sciatic (−28.84° ± 3333.64°) and tibial crush injuries (−40.12° ± 2.17°) (p < 0.01), but was the same after peroneal crush injury (11.60° ± 7.61°) (p = 0.23). The maximum angle of dorsiflexion decreased compared to the angle for sham-operated animals (44.51° ± 1.20°) after sciatic (27.82° ± 9.89°) and peroneal crush injuries (15.71° ± 4.27°) (p < 0.05) but actually increased after tibial crush injury (59.24° ± 3.01°) (p < 0.01). Scores for the SFI decreased after sciatic (−78.4 ± 3.29) and tibial nerve crush injuries (−84.4 ± 4.94), but did not change after peroneal crush injury (−6.9 ± 3.67). Maximum angle of plantar and dorsiflexion, and scores for the sciatic function index returned to normal values 4 weeks after the crush injuries.

2-D digital video ankle motion analysis is a more sensitive method to evaluate functional results in the rat sciatic nerve model than the SFI. Use of this method for evaluation of results after nerve suture and graft repair, however, remains to be determined.