Weber B Fracture of the Lateral Malleolus with Concomitant Anterior Talofibular Ligament Injury following an Ankle Supination Injury

Role of Lateral Ankle Ligaments in Vertical Stability of the Fibula: A Cadaveric Model

BACKGROUND

In unstable ankle fractures, the role of the deltoid and syndesmosis ligaments has been widely studied. However, it is uncertain what the importance of the lateral ankle ligament complex (LALC) is in the vertical stability of the fibula. Given its anatomical position, it should prevent the proximal translation of the fibula. This study aims to evaluate the role of the LALC in stabilizing the fibula in the vertical plane.

METHODS

Eleven below-knee cadaveric specimens were used in this study. Proximal traction of the fibula was performed by applying 50 N in the intact state and after sequential transection of the syndesmotic ligaments, anterior talofibular ligament (ATFL), and the calcaneofibular ligament (CFL). At each stage, the proximal displacement of the fibula was measured. One-way repeated measures analysis of variance with post hoc Bonferroni correction was carried out to determine any significant differences between the groups. A P value <.05 was considered statistically significant.

RESULTS

The vertical displacement of the fibula in the intact state, and after sequential transection of syndesmotic ligaments, ATFL, and CFL was 1.96 ± 1.19 mm, 3.96 ± 1.33 mm, 5.9 ± 1.73 mm, and 10.22 ± 2.76 mm, respectively. There was no significant difference in the proximal displacement of the fibula between the intact and the syndesmotic ligaments groups (P < .05). However, when the syndesmotic ligaments were transected in conjunction with ATFL ± CFL, a significant difference was observed compared to the intact state (P < .001).

CONCLUSION

The complete disruption of syndesmotic ligaments did not significantly increase the proximal displacement of the fibula. However, when the ATFL ± CFL were additionally disrupted, there was a significant increase in the vertical translation of the fibula.

CLINICAL RELEVANCE

To our knowledge, this is the first study describing that LALC plays a paramount role in the vertical stability of the fibula. Concomitant syndesmosis and LALC should be suspected in an axially unstable fibular fracture with a significant proximal displacement.

Diagnosis and treatment of chronic lateral ankle instability with ligamentum bifurcatum injury: An observational study

This study aimed to report our institution's experience in the diagnosis and treatment of chronic lateral ankle instability (CLAI) with ligamentum bifurcatum (LB) injury.This retrospective study included 218 consecutive patients with CLAI who underwent surgery from January 2012 to December 2015. The 218 patients received tendon allograft reconstruction of the lateral ligament. CLAI was combined with LB injury in 51.4% (112/218) of patients. The 112 patients with concurrent LB injury had this treated simultaneously; 36 patients underwent excision of the anterior process of the calcaneus, 68 underwent LB repair, and 8 underwent LB reconstruction. Patients returned for a clinical and radiologic follow-up evaluation at an average of 31 (range, 24-35) months postoperatively. Outcomes were assessed by comparison of pre- and postoperative American Orthopaedic Foot and Ankle Society (AOFAS) scores, visual analog scale pain scores, Karlsson scores, and radiographic assessment.Of the patients with concurrent LB injury, 82.1% (92/112) returned for final evaluation. Postoperatively, most patients recovered very well. However, the outcome was not ideal in those who underwent excision of the anterior process of the calcaneus; there were significant postoperative decreases in talar tilt (P < .05) and anterior drawer (P < .05), but there was no significant postoperative improvement in visual analog scale pain score and AOFAS score. Patients who underwent LB repair or reconstruction had an excellent or good outcome regarding patient subjective self-assessment, pain scores, Karlsson scores, and AOFAS scores at final follow-up.Patients with CLAI often have concurrent LB injury. The diagnosis of LB injury can be missed or delayed. Clinicians should closely examine the LB in cases of CLAI, and should surgically repair or reconstruct the LB when necessary.