Anatomical Study Of Lateral Ankle Ligament And Clinical And Biomechanical Research On Their Reconstruction

Background and objectiveAnkle sprain is common at all levels of athletic participation. It takes up about 1/6 of sports-related injuries. Anterior talofibular ligament (ATFL), calcaneofibular ligament(CFL) and posterior talofibular ligament (PTFL) make up the main portion of lateral collateral ankle ligaments, ATFL and CFL are the most important stabilizer for lateral ankle. ATFL and CFL injury may cause ankle instability and destroy ankle function seriously. Although 80% to 85% of acute ankle sprains are successfully treated with functional ankle-rehabilitation program, the remaining 15% to 20% have recurrent ankle instability and reinjury, necessitating surgical intervention. About 80 kinds of surgical procedures have been described in the management of chronic lateral ankle instability(CAI), which can be divided into anatomical repair through direct suturing of the ligament and non-anatomic repair consisting of tenodesis and reconstruction of the lateral ligament to decrease hypermobility of the ankle and subtalar joints. Anatomical repair procedure have the advantages of direct repair the injuried lateral ankle ligament and excellent clinical results in the long run. However, its limitation is obviously and not fit for most of the cases. Non-anatomical tendodesis techniques have the advantages of being fit for most of the cases and restoring the ankle stability effectively, however, they ruin the anatomical structure of lateral ankle and loss of other tendon's function. Therefore, its clinical outcomes , especially the long-term results are not as good as anatomical repair procedures. In other words, it is difficult to arrive at a consensus as to the optimal surgical treatment for CAI in reported 80 kinds of procedures.The aim of this study was to direct the diagnosis and surgical treatment of lateral ankle ligaments injury and verify the feasibility of the procedure of mini-open reconstruction of lateral collateral ankle ligaments with partial peroneus brevis tendon(PBT) by analyze the anatomical feature of lateral ankle ligaments and relevant structure; using the technique of mini-open reconstruction of lateral collateral ankle ligaments with partial PBT and evaluate its clinical results in correct CAI; design a further biomechanics experiment to verify the effect of the operative method on stability and mobility of lateral ankle.Materials and methods1. Research on the anatomical feature of lateral ankle ligaments and relevant structureAnatomical feature of lateral ankle ligaments and other relevant structure research was performed on 18 fresh ankle cadaver specimens(including 8 pairs) which constituted 16 males and 2 females(8 right,10 left).The superficial muscles, fascia were carefully removed from 18 ankles to expose the lateral ankle ligaments, PBT and inferior peroneal retinaculum. Mean values for the length, width and angle of ATFL and CFL were measured. The precise location of insertion points and course of each ligament was observed and noted with ankle placed in neutral position. The length of PBT and the tendon needed for the reconstruction procedure should be measured as well.2. Biomechanics experiment to verify the effect of the operative method on stability and mobility of lateral ankleUsing universal biomechanical testing machine measure the anterior talar translation(ATT) and talar tilt(TT) on 6 fresh ankle cadaver specimens(3 pairs) under the intact condition of lateral ankle ligaments. Then, randomly divided 3 pairs of specimens into 2 groups of using mini-open reconstruction of lateral ankle ligaments with partial PBT technique(mini-open group) and Watson-Jones technique(W-J group) and measure ATT and TT once again. According to the data, evaluation of the effect of mini-open technique on stability and mobility of lateral ankle.3. Evaluation of the results of Mini-open reconstruction of lateral ankle ligaments with partial PBT by clinical follow-up.11 cases with CAI were treated with the technique of mini-open reconstruction of the lateral ankle ligaments with partial PBT. The average surgery age was 24.27±8.71 years (16～41 years). The mean delay between the initial episode of ankle sprain and the surgery was 9.2 months (2～25 months). A 3-cm curved incision was made to explore the origin of ATFL on the fibular, the insertion of ATFL on the talus, and the insertion of CFL on the fibular using"moving windows"technique. Half of PBT was taken to reconstruct the ATFL and CFL through the bone tunnel from the insertion of CFL to the insertion of ATFL on the fibular, and then fixed on the talus by suture anchor or shape"V"bone tunnel. Postoperatively, patients were examined with Magnetic Resonance Image(MRI), stress X-rays and comparative stability of bilateral ankle inspection at clinical follow-up. The function of the ankle were evaluated by American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot scale.Results1. ATFL was a flat, quadrilateral ligament and it made mean angle of 8.02±5.40°(range 0.02°-19.85°)with horizontal plane, and a mean angle of 92.29±9.58°(range 70.15°-107.16°)with vertical plane. CFL was a flat oval ligament and it made mean angle of 65.84±8.48°(51.46°-80.86°)with horizontal plane, and a mean angle of 24.21±8.51°(9.14°-38.54°)with vertical plane. The length of PBT was longer than the tendon needed for the mini-open technique reconstruction of lateral ankle ligaments(P<0.05).2. In biomechanics experiment, intact group, mini-open group and W-J group made mean distance of 5.32±1.16mm ( range 3.05mm-6.03mm ) ,5.37±1.05mm ( range 4.16mm-6.03mm)and 4.27±1.95mm(range 2.17mm-6.03mm)in ATT test respectively ,and mean angle of 4.41±0.43°(range 3.96°-5.19°),5.72±0.08°(range 5.65°-5.81°)and 5.88±0.78°(range 4.73°-6.35°)in TT test. The results of TT of mini-open group were larger than intact group ,but smaller than 9°(the criterion of diagnosis of CAI for TT test).3. For 11 CAI cases, the average duration of follow-up was 15.5 months (from 6 to 31 months). The mean AOFAS ankle-hindfoot score was 87.81±6.46 points(range 72 -96 points) at the time of the latest follow-up. MRI results showed that the ruptured lateral collateral ankle ligaments were reconstructed and remodeled well in all patients. There was no recurrence of the ankle instability and other complications.ConclusionATFL and CFL play a important role in maintaining the stability of lateral ankle. The research on the two ligaments and relevant structure provided important information for diagnosis and treatment of lateral ankle ligaments injury and verified the feasibility of the procedure of mini-open reconstruction of lateral collateral ankle ligaments with partial PBT. Biomechanics experiment and clinical study demonstrated that the technique mentioned before can restored the stability of lateral ankle and did not cause any limitation on ankle mobility and means the procedure was a simple and effective method for correcting CAI.