Introduction: The calcaneonavicular ligament (spring ligament) plays a fundamental role in calcaneonavicular static stability and medial longitudinal arch, injury which is related to flatfoot. Objective: The primary objective was to compare the biomechanical behaviour of the spring ligament in a healthy foot and after section and repair with augmentation and transfer of the flexor digitorum longus (FDL). As secondary objectives we have the biomechanical comparison between isolated repair with augmentation associated or not with transfer. Methods: This experimental biomechanical cadaver study evaluates the medial complex in four phases: intact ankle (1); spring injury (2); repair and augmentation (3), and after FDL transfer (4). Talonavicular angular displacement was measured in the three planes of space using an arthrometer and manual spring ligament exploration manoeuvres. Results: Significant differences were found after sectioning the ligament with the abduction and external rotation manoeuvre in the coronal (p = .050) and sagittal (p = .045) planes. Upon augmentation, there was significance in the horizontal plane (p = .047) and after FDL transfer in the horizontal plane (p = .002). However, no significant differences were identified between repair and augmentation and FDL transfer. Conclusion: Ligament section generated instability in the coronal and sagittal plane with abduction and external rotation movements. It should be noted that both surgical techniques were able to restore joint stability, even surpassing that achieved with the ligament intact.
López et al. (Wed,) studied this question.