3D Light Scanner Analysis of the Lateral Collateral Ligaments of the Ankle: An Anatomical Study

Abstract

Category: Basic Sciences/Biologics; Ankle Introduction/Purpose: Recently an anatomical study described a medial connection between the anterior talofibular ligament inferior fascicle (ATFLif), calcaneofibular ligament (CFL) and posterior talofibular ligament (PTFL). Therefore, there is no research evaluating the lateral ligaments and their relationships through a three-dimensional view achieved by a digital marking of their foot prints. The authors hypothesize that a three-dimensional analysis made only by an accurately digital analysis can clarify the lateral collateral ligaments (LCL) connections and their foot prints relations. This work aims to carry out an anatomical study in cadaveric pieces in which the lateral ankle ligaments were dissected and evaluated by a tridimensional scanner that allows a digitally and three-dimensional assessment of their foot prints and connections. Methods: An anatomical study was performed in 11 fresh-frozen ankle specimens. Each ankle was dissected to achieve the amputation of the calcaneus, talus and fibula, keeping the inserts of the footprints of LCL. After that, each bone piece with the insertion remnants of the LCL was submitted to an evaluation by a scanner machine. Surface scans for these bones were collected using a structured light scanner. Each bone piece was set on a 3D automatic turntable to capture a 360° scan and was scanned in two orientations, with 6 scans per orientation. Finally, all the scans were aligned and final fused models were created using the HP DAVID software package and exported to a wavefront 3D object file. The 3D models were imported into Geomagic Studio to calculate surface area of the LCL foot prints. Results: A total of 11 units of each, talus, fibula and calcaneus were dissected from 11 ankles specimens. The ATFL was identified as a two-fascicled ligament and the fibers connecting fibers between the ATFLif and CFL was present in all specimens. In two talus there was only one insertion of the ATFL. After scanning the bones, the authors observed that the foot prints of ATFLif, CFL and PTFL were contiguous at medial side of the fibula, with an average of the surface area of 486,7 mm 2 . The foot print of the CFL on the calcaneus was located at the junction of a vertical line tangent to the highest point of the posterior subtalar with a horizontal line extending from the sinus tarsi in all specimens. Conclusion: This study demonstrated by a 3D analysis that the LCL of the ankle share the same foot print at medial side on the fibula and are all connected since the foot prints of the ATFL inf, CFL and PTFL were contiguous. In the case of associated proximal lesions of the ATFLif and CFL, ligaments repair with a single suture may be considered. This can be applied in surgical procedures in patients with lateral ankle instability.fig