A Preliminary Study to Assess the Relevance of Shear-Wave Elastography in Characterizing Biomechanical Changes in the Deltoid Ligament Complex in Relation to Ankle Position.

BACKGROUND

The purpose of this study was (1) to evaluate the biomechanical properties of the different bundles of the deltoid ligament in various ankle positions in a cohort of healthy adult volunteers; (2) describe the impact of demographic and hindfoot morphology characteristics on their stiffness; (3) to assess the reliability and reproducibility of these measurements.

METHODS

Deltoid ligament complex of both ankles were assessed by shear-wave elastography (SWE) in 20 healthy patients resting on hinge support. The propagation shear-wave speed (SWS) in ligaments was measured, which is related to the tissue's elastic modulus. The following ligaments were analyzed in a neutral position and then in varus, valgus, dorsal, and plantar flexions: tibionavicular ligament (TNL), tibiocalcaneal ligament (TCL), the superficial posterior tibiotalar ligament (SPTL), the anterior tibiotalar ligament (ATTL), and the deep posterior tibiotalar ligament (DPTTL).

RESULTS

The mean SWS increased between neutral and 20 degrees valgus position for TCL (4.08 ± 0.78 m/s vs 5.56 ± 0.62 m/s, respectively; < .0001) and for DPTTL (2.58 ± 0.52 m/s vs 3.59 ± 0.87 m/s, respectively; < .0001). The mean SWS increased between neutral and 30 degrees plantarflexion for ATTL (2.11 ± 0.44 m/s vs 3.1 ± 0.5 m/s, respectively; < .0001) and TNL (2.96 ± 0.66 m/s vs 4.99 ± 0.69 m/s, respectively; < .0001). The mean SWS increased between neutral and 20 degrees dorsal flexion for SPTL (4.2 ± 1 m/s vs 5.45 ± 0.65 m/s, respectively; < .0001).Women had less DPTTL SWS than men in the neutral position (2.37 ± 0.35 m/s vs 2.71 ± 0.49 m/s, respectively; = .007). Other demographics had no impact on the SWS value of other ligaments. All inter- and intraobserver agreements were good to excellent.

CONCLUSION

This study presents a reliable and reproducible SWE measurement protocol to describe the physiological function of all bundles of the medial collateral ligament in healthy adults.

CLINICAL RELEVANCE

This examination technique can be available to orthopaedic surgeons, allowing reliable and reproducible monitoring of the SWS of the various ligaments constituting the medial collateral plane. The biomechanical values described in this study may give insight into in what position medial ankle ligament reconstruction should be tensioned.