[Biomechanical comparison of Evans procedure and Chrisman-Snook technique for the treatment of II degree lateral collateral ligament of ankle joint].

Objective: To measure the stability of Evans procedure and Chrisman-Snook technique in the treatment of II degree lateral collateral ligament of ankle joint, and provide basis for treatment and prognosis.

Methods: From July 2008 to June 2009,18 frozen corpes were collected, including 10 males and 8 females, with an average age of fresh 39.3 +/- 11.2 years. The frozen corpes were randomly divided into three group, including normal controls(group A), Evans procedure (group B) and Chrisman-Snook technique ( group C), 6 specimens in each group. Anterior talofibular ligament and calcaneofibular ligament were cut off to cause II degree lateral collateral ligament in group B and C. Evans procedure or Chrisman-Snook technique were applied to restore lateral collateral ligament, and measure biomechnics. The displacement of tibiotalar joint and subtalar joint were observed.

Results: (1) The lateral stress results of tibiotalar joint showed the displacement by Evans procedure (group B) was greater than other groups (P < 0.0001). There were no significant differences between group A and C (P > 0.05). (2) The lateral stress results of subtalar joint showed the displacement by Evans procedure (group B) was greater than other groups (P< 0.0001). There were no significant differences between group A and C (P > 0.05).

Conclusion: Ankle instability is caused by ankle joint lateral collateral ligament injury. Chrisman-Snook technique is better than Evans procedure in stability on the early stage of ankle joint restoration, and conform to principle of biomechanics.