Abstract
Deltoid ligament insufficiency has been shown to decrease tibiotalar contact area and increase peak pressures within the lateral ankle mortise. Sectioning of the deltoid ligament has been shown to decrease tibiotalar contact area by 43%. This detrimental effect may create an arthritic ankle joint if left unresolved. Reconstructive efforts thus far have been less than satisfactory. Pankovich and Shivaram described the deltoid ligament as having superficial and deep components based on insertion sites. The superficial layer originates from the anterior colliculus of the medial malleolus and inserts on the navicular, calcaneus and talus. The deep layer originates from the intercollicular groove and posterior colliculus and inserts on the talus. Boss and Hintermann noted that the most consistent and strongest bands of the deltoid were the tibiocalcaneal and posterior deep tibiotalar ligaments. Chronic deltoid ligament insufficiency may be seen in several disorders including trauma and sports injuries, posterior tibial tendon disorders, prior triple arthrodesis with valgus malunion, or total ankle arthroplasty with improper component positioning or pre-existing ligament laxity. The reconstruction of the deltoid ligament in these settings may be critical to the prevention of tibiotalar arthrosis or failure of ankle prostheses from edge loading and polyethylene wear.
The reconstructive technique we describe, under low torque, was able to restore eversion and external rotation stability to the talus, which was statistically similar to the native deltoid ligament. In addition, though we maximally tension this graft to give the most secure repair possible, we did not note any increased stiffness in the ankle joint through our measurement techniques. This unusual, positive secondary effect is different from that noted in studies of lateral ligament reconstruction, where ligament tensioning by all methods attempts to reproduce the native tension and not exceed it. All medial ankle ligament repairs of substance involve some type of tendon-weave (whether autograft or allograft) to achieve reconstruction. Our technique develops its strength not only from the anatomic orientation of the reconstructed ligament, but the strength of the components chosen to fix the tendon graft to the bone. The use of Endobuttons allows the entire graft to sit within the tunnels, without the potential violation of the graft ends achieved through techniques utilizing interference screw fixation. Tensioning the graft proximally through the tibia against a rigid distal construct allows greater tension to be placed on the graft at the deltoid ligament site itself than techniques which employ distal tensioning while holding the ankle into inversion. Finally, the use of a looped graft proximally secured with a post that may be moved even further proximally at the surgeon's discretion creates superior tension to achieve medial column rigidity in grossly unstable situations. Thus, given the critical importance of the deltoid ligament and the relative paucity of repair/reconstruction options available, we believe this novel approach will assist the clinician in anatomically reconstructing this challenging condition.
Deltoid ligament reconstruction technique using semitendinosis allograft, with superimposed line drawing demonstrating orientation of looped graft.
