Biomechanical And Clinical Research On The Functional Reconstruction Of Laterally Instable Ankle

Objective: This research mainly is about respectively using 3d finite element mechanical tests and the results of different surgical treatment options to compare the efficacy and reliability of three different ways to reconstruct the stability of ankle joint,and to provide theoretical basis for choosing the method of clinical treatment for lateral ankle instability.Methods: First of all,three-dimensional finite element model was built and its reliability was verified by three steps;(1)Siemens dual-source CT(Somatom Definition Definition Flash)was applied on a 25 year old healthy volunteer to scan from10 cm superior to the ankle to the palm of the foot.Total acquisition interval of each layer was 0.625 mm,reconstruction thickness;0.625 mm,281 pieces of two-dimensional CT images with flat resolution of 512×512 were collected and saved as DICOM format file.(2)3D reconstruction of CT image;CT images in DICOM format were imported into the Materialise Mimics17 3D reconstruction software by Import Image command.Coronal and sagittal planes were set up manually and primary 3D models of 14 pieces of bone and articular cartilage including tibia,fibula,talus and calcaneus,cuboid,navicular bone,3 pieces of wedges,5 pieces of metatarsal bones were constructed.(3)Ligament surface models of anterior talofibular ligament,calcaneofibular ligament,posterior talofibular ligament,peroneus longus tendon,Peroneus brevis tendon and ligamentum triangulare were built according to the anatomical relations of bone and soft tissues.(4)Vertical,antero-posterior and lateral loads were enforced on the reconstructed model and validity of biomechanical tests results was tested by comparing them to current literature.Second;collateral lateral ligament injury was made on the 3D models,and it was reconstructed respectively using part of the peroneal tendon,long and short peroneal tendon and allogeneic tendon.Finite element tests were carried out in all those groups.Displacement of tibial joint and subtalar joint under lateral stress test was observed.(1)I ° lateral collateral ligament injury was simulated by removing talofibular ligaments.(2)II° lateral collateral ligament injury was simulated by removing talofibular ligament andcalcaneofibular ligament.(3)Half the thickness of the long peroneal tendons were used for the reconstruction of anterior talofibular ligament or talofibular+ calcaneofibular ligaments.Half the thickness of the short peroneal tendon was used for the reconstruction of talofibular ligament or talofibular calcaneofibular ligaments.Allogeneic tendon was used for the reconstruction of talofibular ligament or talofibular calcaneofibular ligaments.Ligament injury models were built on 3D models to evaluate the effect of different surgical approaches.Third;Clinical evaluation of different surgical methods on patients with chronic external ankle instability.Patients who were diagnosed with II °lateral collateral ligament injury through physical examination and imaging tests were divided into three groups according to the patient’s choice of treatment;control group adopted 1/2 short peroneal tendon and 1/2 long peroneal tendon reconstruction,the experimental group underwent allogeneic tendon reconstruction.AOFAS and VAS scores were applied in follow visits of average 18 months.Treatment results were compared among the three groups using independent sample t-tests and Comparison between groups using independent sample t test with SPSS 17.0 statistical software,difference was considered significant when P < 0.05.Results: Biomechanical analysis on 3D models revealed that equivalent stress of talofibular ligament and calcaneofibular ligament was weaker than reconstruction with 1/2 thickness peroneus longus or brevis tendon,but similar to the equivalent stress of normal foot.In the anterior drawer test showed that the equivalent stress of ATFL and CBL in allogeneic tendon reconstruction group was more than reconstruction with 1/2 thickness peroneus longus or brevis tendons.In the clinical studies,the functional recovery scores were similar(P > 0.05)after reconstruction with 1/2 thickness peroneus longus or brevis tendons and with allogenic tendons right after the surgical intervention.However,talar tilt angle and talus removal distance at the last follow up were significantly(P < 0.05)less than that before the surgery in both groups;moreover,AOFAS was also significantly(P<0.05)higher than that before the surgery.In autologous fibular tendon group,response time was significantly shorter in the last follow up than before the treatment(P<0.05).Peroneal muscle reaction time at the end of the follow-up was lower in the allogeneic tendon graft group than before treatment(P < 0.05).AOFAS scores,talar tilt angle,talus removal distance,fibular muscle reaction time were not significantly different in the three groups at the last follow up.Conclusions: Three dimensional finite element analysis on different experimental and clinical settings show that stability and functional capacity of lateral collateral ligament reconstruction of the ankle joint by allogeneic tendon is similar toreconstruction with autologous peroneus longus or brevis tendon.Moreover,ligament reconstruction with allogeneic tendon is less invasive,saves operation time and can avoid donor site morbidity.