The effect of collateral ligament release on ankle dorsiflexion: an anatomical study

Ankle stiffness is a common complication after ankle fracture, reconstructive surgery or total ankle replacement, and the usual limitation is in dorsiflexion. There are few articles in the literature concerning this frequent problem, and furthermore they are not recent and tend to be controversial. The purpose of this anatomical study was to evaluate and quantify the effect of ankle collateral ligament release on dorsiflexion, specifically the amount of increase in ankle dorsiflexion following section of the two ligaments most often implicated in ankle stiffness: the deep posterior tibiotalar ligament (dPTTaL, or posterior deep deltoid) and the posterior talofibular ligament (PTaFL).

We dissected 18 adult fresh cadaveric ankle joints, and with an electronic goniometer combined with an electronic dynamometer measured their mobility in dorsiflexion before and after transection of each ligament separately, and the two ligaments combined.

The results showed a significant difference between the two groups of ankles with section of the dPTTaL resulting in a greater increase in ankle dorsiflexion than section of the PTaFL (mean 7.45° vs. 3.5°, respectively; p<0.001). Combined section of both ligaments improved the gain in ankle dorsiflexion more than isolated section of each ligament, but was not statistically significant (p=0.88).

If after gastrocnemius recession or Achilles tendon lengthening persistent restriction remains in ankle dorsiflexion, the results of our study demonstrate that the next step should be release of the dPTTaL.