Basic And Clinical Study Of Posterior Malleolus Fracture

PART ? ANATOMICAL STUDY OF POSTERIOR MALLEOLUS EXPOSURE WITH DIFFERENT INTERVAL OF FLEXOR HALLUCIS LONGUS MUSCLEOBJECTIVE: The aim of this cadaveric study was to compare the osseous surface of posterior malleolus areas visible through contralateral incision via different flexor hallucis longus.METHODS: Ten leg specimens were randomly divided into two groups,group A and group B,each group had 5 fresh amputated specimens far from the middle of the leg.The lateral interval of flexor hallucis longus was exposed through posterolateral incision in group A,and the medial space of flexor hallucis longus was exposed through posterolateral incision in group B.For each approach the surface areas visualized were outlined with use of a Kirschner wire.Each leg was then stripped of soft tissue and a 3D model was created with use of CT data.The visible surface area obtained with each approach was mapped and quantified with use of the markings created with the Kirschner wire.At the same time,secondary injuries were recorded.The collected data were processed by SPSS 25.0 software.RESULT: Group A needed more stripping of flexor hallucis longus and took greater risk of damage to nutrient vessels of local skin flaps;Group B could expose more posterior medial malleolus fragments,even those involving posterior colliculus of medial malleolus;Group B had better exposure to posterior malleolus,with significant difference(t=-2.073,p=0.027 < 0.05).CONCLUSION:The exposure of posterior malleolus through posterolateral incision of medial interval of flexor hallucis longus can reduce the collateral injury or complications.It is a better choice for Haraguchi type ? posterior malleolus fracturePART ? THREE KINDS OF SCREW FOR FIXING HARAGUCHI I POSTERIOR MALLEOLUS FRACTURE: A FINITE ELEMENT ANALYSISOBJECTIVE: To compare the effect of three kinds of screw made from different materials for fixing Haraguchi I posterior malleolus fracture.METHODS: CT data of ankle and foot of normal male adult volunteers were obtained.Three kinds of screw materials,titanium alloy screw,polylactic acid absorbable screw and magnesium alloy absorbable screw,were established.Three-dimensional finite element models of Haraguchi I posterior ankle fracture were simulated by two screw,and the finite element analysis was carried out.The biomechanical characteristics of Haraguchi I posterior ankle fracture fixed by three kinds of screw were compared.RESULT:(1)Establishment of posterior malleolus fracture model: The model had good reducibility,and the results of articular contact relationship,peak stress and stress distribution were consistent with the results of relevant literature,so the next finite element analysis could be carried out.(2)Finite element analysis results: Under all stress loading modes,the stress peak values of the three kinds of screw were almost as same as those of the corresponding bone around the screw.Among the three screw fixation models,the maximum equivalent stress of titanium alloy screw was the largest,and the maximum equivalent stress of cortical bone was the same.The maximum displacement of different screw and distal part of fracture was very closely.When the load became larger and larger,the displacement of screw and fracture correspondingly increased.Even under 1500 N load,the maximum displacement was within 1 mm.CONCLUSION: The establishment of Haraguchi I posterior malleolus fracture model is reliable.Magnesium alloy absorbable screw can achieve sufficient biomechanical stability.PART ? THE POSTERIOR PILON FRACTURE: TREATMENT AND RESULTS VIA A NEW MODIFIED POSTEROLATERAL APPROACHOBJECTIVE: To evaluate the clinical value of a posterolateral approach in the treatment of posterior Pilon fracture.METHODS: A retrospective study was conducted on 38 patients with posterior Pilon fracture who underwent surgical treatment in the department of traumatic / hand/ foot and ankle surgery in Guilin People's Hospital from January 2015 to January 2018.The patients were divided into three groups according to the different surgical approaches adopted during the operation: the posterolateral approach group(group A),the new modified posterolateral approach group(group B)and the combined approach group(group C).There were 13 cases in group A,15 cases in group B and 10 cases in group C.There was no significant difference in gender,age,injury side,type of posterior malleolus fracture,time from injury to operation,complications and basic diseases among the three groups(P > 0.05).The length of incision,operation time,intraoperative blood loss and incidence of complications were recorded.BurwellCharnley radiological evaluation criteria were used to evaluate the quality of fracture reduction.Periodic follow-up visits were made after discharge to record the healing time of fracture.At the last follow-up,American Orthopaedic Foot and Ankle Society(AOFAS)Ankle-Hindfoot Score and Visual Analogue Scale(VAS)were used to evaluate the treatment effect.The collected data were processed by SPSS 25.0 software.RESULT: 35 patients were followed up completely,3 patients failed to follow up completely.The average duration of follow-up was was 18.6(range,12-45)months,.All fractures healed completely,and the average healing time was 3.5(range,2-6)months.At the last follow-up,no fracture reduction loss,internal fixation fracture or failure occurred in all patients.There were significant differences in incision length,operation time,intraoperative blood loss and AOFAS score at the last follow-up(p< 0.05).There was no significant difference in fracture healing time and average VAS score among the three groups(p > 0.05).According to Burwell-Charnley radiological evaluation criteria,1 case in group A had unsatisfactory reduction of posteromedial bone mass,and the rest achieved anatomical or functional reduction.The incidence of three complications were 16.7%(2/12),7.8%(1/13)and 30%(3/10)respectively.Among them,1 case in group B had hypoalgesia of plantar tenderness,which was completely relieved after neurotrophic treatment;1 case in group C had infection of posterolateral incision,which was cured after debridement and dressing change;1 case in group A and C had obvious traumatic arthritis of ankle joint;1 case in group A and C had flexion contracture deformity of thumb and toe,without obvious limitation of daily life.CONCLUSION: The new modified posterolateral approach and combined internal and external approach can achieve better results than the posterolateral approach in the treatment of Pilon fracture.