LAXITY AND FLEXIBILITY OF THE ANKLE FOLLOWING RECONSTRUCTION WITH THECHRISMAN-SNOOK PROCEDURE

The effect of reconstruction of the anterior talofibular ligament with the Chrisman-Snook procedure on neutral zone laxity (anterior-posteri or displacement at low loads) and flexibility (a measure of the nonlin ear load-displacement response) of the ankle was investigated iri vitr o during the anterior drawer test. Neutral zone laxity was defined as the magnitude of anterior-posterior displacement of the ankle joint at +/-2.5 N of applied load. The flexibility parameter was defined as th e slope of a line between the natural logarithm of the anterior load a pplied to the ankle and the resulting displacement. After reconstructi on with the Chrisman-Snook procedure, the values for neutral zone laxi ty of the ankle were significantly less than normal at 0 degrees of pl antar flexion, whereas the flexibility values were significantly great er than normal, This study revealed that, after the Chrisman Snook pro cedure, values for ankle flexibility are not restored to normal even i f those for neutral zone laxity are reduced to less than normal. The f indings suggest that this nonanatomical reconstruction Procedure does not reproduce normal kinematics of the ankle joint. This may help expl ain some of the adverse clinical reports associated with the Chrisman- Snook reconstruction procedure.