Changes in tibiotalar area of contact caused by lateral talar shift

The Volkmann dogma: a retrospective, long-term, single-center study

“…A change in the contact stresses of the joint. It was demonstrated experimentally that a lateral talus shift of 1 mm produces a decrease in the contact area of 42% [18,19], which underlines the importance of the lateral malleolus, considering that ''the talus not only goes with the lateral malleolus, but also stays with it'' [20]. In relation to the assumed reduction in contact area in the presence of a Volkmann triangle, statistical experimental studies have shown that the larger the Volkmann triangle, the greater the change in the contact area [7,9].…”

Treatment of osteochondral defects of the talus

“…433 The load-bearing area of the ankle joint is relatively small compared to the forces it transmits. 319,323 The load on the remaining cartilage increases when the contact surface area decreases in size, for example, after a malreduction of an ankle fracture or by an OCD. Ramsey and Hamilton found that a 1-mm lateral talar shift, as occurs after an ankle fracture malunion, reduces the contact area by 42%, and a 2-mm lateral shift reduces the contact area by 58%.…”

“…Ramsey and Hamilton found that a 1-mm lateral talar shift, as occurs after an ankle fracture malunion, reduces the contact area by 42%, and a 2-mm lateral shift reduces the contact area by 58%. 323 A 1-mm shift generally is considered acceptable, while a 2-mm shift should be surgically corrected because of the high risk of degenerative changes. 203 Apparently, the talar cartilage can adapt to an increase in contact stress as great as 42%.…”

“…367 Th e loads were applied to the tibia, as was done in previous studies. 253,264,323 Th e reallife situation might have been better imitated by also loading the fi bula, which transmits 7% of the total force through the lower leg. 157 However, loading the fi bula would probably not have had any notable eff ect on the results because the pressure distribution would have shift ed slightly to the lateral side, 389 with minor eff ects on the medially located implant.…”

Comments on Hsu et al.: Surgical treatment of syndesmotic diastasis: emphasis on effect of syndesmotic screw on ankle function

“…This statement is based on the studies of Ramsey and Hamilton, and later of Lloyd et al When the talus moves 1 mm laterally, the contact area in the tibiotalar articulation is decreased by 42%. This results in an increase in the stress per unit area on the articular cartilage [3,4].…”