Study: Surgery May Be a Better Approach for Deltoid Ligament Rupture

Though it seems like a drastic measure, clinical research shows surgery could be a better option for patients suffering from a torn deltoid ligament.

An analysis of 10 ankles from cadavers found that a complete deltoid tear caused major ankle instability in anterior translation, external rotation, and eversion. Deltoid repair is strongly recommended to treat a complete tear, but since the ankle’s deltoid ligament frequently ruptures in a fracture, natural healing is favored over surgery because normal fracture healing provides the deltoid with enough time to heal.
 
Alex Brady, of Steadman Philippon Research Institute in Vail, Colo., and colleagues have noted that conservative management after ankle fracture accompanied by deltoid rupture has shown poor outcomes both acutely and frequently leading to arthritis. The contribution of the anterior and posterior bundles of the deltoid ligament to the stability of the ankle remains unknown, as does the effect of deltoid repair versus repair with augmentation.
 
Brady sought to determine the biomechanical role of the native anterior and posterior deltoid ligament in ankle stability and to determine the efficacy of simple suture vs augmented repair of each bundle.
 
“We hypothesized that sectioning of the anterior and posterior deltoid ligaments would significantly increase ankle laxity in eversion, external rotation, and anterior translation, repairing the anterior and posterior deltoid ligaments using suture anchors would significantly reduce ankle laxity compared to the sectioned states, and augmenting the repairs with an Internal Brace would further reduce ankle laxity compared to the suture anchor repair,” Brady reported.
 
To accomplish this, Brady and his team dissected 10 cadaveric ankles (50.9 mean age, male) to the medial ligamentous structures and mounted them on a six-degrees-of-freedom robotic arm. The specimens underwent biomechanical testing in eight sequential states: 1) intact, 2) anterior deltoid cut, 3) anterior repair, 4) internal brace tibia-spring augmentation 5) internal brace tibial-calcaneal augmentation, 6) posterior deltoid cut, 7) posterior repair, and 8) complete deltoid cut.
 
Biomechanical testing consisted of three tests: 1) anterior drawer 88 N, 2) eversion 5Nm, 3) external rotation 5 Nm, each run at 0° and 25° of plantarflexion under 100 N of joint compression.
 
The complete deltoid cut state had a significantly higher anterior translation, eversion, and external rotation at 0 degrees and 25 degrees of plantar flexion compared to all other states (+8.6mm ATT p=0.01-9, +34.1 degrees Eversion p=0.01-9, +14.7 degrees p=0.01-9 ER compared to native at 0 degrees plantar flexion, respectively). The anterior deltoid cut showed a significant increase in eversion at 25 degrees of plantarflexion compared to the native state (+6.65 degrees p=0.0007). The anterior deltoid repair alone showed no significant decrease from the anterior deltoid cut, however, both augmented anterior repairs showed significant decreases in eversion (-5.1 degrees, p=0.023;-5.0, p=0.026, respectively).
 
“The most important finding of this study was that the complete deltoid tear caused major ankle instability in anterior translation, external rotation, and eversion” Brady reported. “Therefore, the deltoid repair is strongly recommended in the clinical setting ofa complete tear.”
 
Brady found the anterior deltoid tear alone caused significant eversion instability at 25 degrees of plantar flexion, which was significantly reduced by the first augmented repair, the addition of a second augmentation showed no additional benefit over a single augmentation. Cutting the posterior deltoid in the setting of an augmented anterior repair showed no effect on ankle kinematics, therefore an augmented anterior repair can be seen as sufficient to stabilize a complete deltoid tear.
 
“Our findings suggest that surgeons may need to reconsider non-operative treatment on complete anterior deltoid injuries and that repair with augmentation offers superior stability,” Brady reported.