Fracture of the tibia with additional injury of the ankle joint. A frequent and undervalued combination

Summary There are 2 types of a combined tibia fracture and ankle injury: in Type I the tibia fracture extends directly into the ankle joint, in Type II the tibia fracture goes along with a fracture of the fibula and disruption of the fibular-tibial syndesmosis. This type of fracture must be distinguished from a pilon tibiale fracture. The typical mechanism for this combined tibia and ankle injury is the indirect torsional trauma with pronation-eversion. From 1995 to 1997 188 patients with fractures of the tibia were treated by internal fixation in our Trauma Department. 27 of these patients (13.6 %) had a combined tibia and ankle injury. Most of the tibia fractures were located in the distal third, a spiral fracture (16 patients) or a comminuted fracture (6 patients), and another group extending directly into the ankle (5 patients). The ankle lesion was a distal fibular fracture (Weber Typ B + C) in 14 patients, a proximal fibular fracture (Type maisoneuve) in 6 patients, a postero-lateral fragment in 11 cases and a fracture of the medial melleolus in 10 cases. A disrupture of the anterior tibio-fibular syndesmosis was seen in 18 patients, 3 times as an isolated lesion of the ankle joint without fracture of the fibula. The osteosynthesis of the tibia fracture was performed with an unreamed tibia nail in 20 patients, with elastic-biologic plate fixation in 6 and with external fixation in 1 patient. The fibula fractures were stabilized by small fragment titaneum plates, the dorsolateral fragment and the medial malleolus were stabilized by lag-screws, the tibio-fibular ligament was sutured and, in a few cases only, held in place by a positioning screw. The outcome was controlled after 20,7 month according to the Phillip's Score (1996). We found not more than one pour results. It must be considered, that most of the combined injuries of the tibia and the ankle joint concerning 13,6 % of all tibia shaft fractures are usually not recognized and may result in an arthrosis of the ankle joint. The attention should be focused to the ankle joint in any spiral fractures of the distal tibia after indirect trauma, especially with a proximal fibular fracture or an intact fibula. Additional X-ray examination of the ankle joint is recommended during internal fixation of the tibia. Posttraumatic arthrosis of the ankle joint can be prevented by diagnosis and adequate anatomical reconstruction of the additional ankle joint injury.      

Fracture of the tibia with additional injury of the ankle joint. A frequent and undervalued combination Eine h?ufige, aber wenig beachtete Kombination

There are 2 types of a combined tibia fracture and ankle injury: in Type I the tibia fracture extends directly into the ankle joint, in Type II the tibia fracture goes along with a fracture of the fibula and disruption of the fibular-tibial syndesmosis. This type of fracture must be distinguished from a pilon tibiale fracture. The typical mechanism for this combined tibia and ankle injury is the indirect torsional trauma with pronation-eversion. From 1995 to 1997 188 patients with fractures of the tibia were treated by internal fixation in our Trauma Department. 27 of these patients (13.6 %) had a combined tibia and ankle injury. Most of the tibia fractures were located in the distal third, a spiral fracture (16 patients) or a comminuted fracture (6 patients), and another group extending directly into the ankle (5 patients). The ankle lesion was a distal fibular fracture (Weber Typ B + C) in 14 patients, a proximal fibular fracture (Type maisoneuve) in 6 patients, a postero-lateral fragment in 11 cases and a fracture of the medial melleolus in 10 cases. A disrupture of the anterior tibio-fibular syndesmosis was seen in 18 patients, 3 times as an isolated lesion of the ankle joint without fracture of the fibula. The osteosynthesis of the tibia fracture was performed with an unreamed tibia nail in 20 patients, with elastic-biologic plate fixation in 6 and with external fixation in 1 patient. The fibula fractures were stabilized by small fragment titaneum plates, the dorsolateral fragment and the medial malleolus were stabilized by lag-screws, the tibio-fibular ligament was sutured and, in a few cases only, held in place by a positioning screw. The outcome was controlled after 20,7 month according to the Phillip's Score (1996). We found not more than one pour results. It must be considered, that most of the combined injuries of the tibia and the ankle joint concerning 13,6 % of all tibia shaft fractures are usually not recognized and may result in an arthrosis of the ankle joint. The attention should be focused to the ankle joint in any spiral fractures of the distal tibia after indirect trauma, especially with a proximal fibular fracture or an intact fibula. Additional X-ray examination of the ankle joint is recommended during internal fixation of the tibia. Posttraumatic arthrosis of the ankle joint can be prevented by diagnosis and adequate anatomical reconstruction of the additional ankle joint injury.     

Is Fibular Fracture Displacement Consistent with Tibiotalar Displacement?

We believed open reduction with internal fixation is required for supination-external rotation ankle fractures located at the level of the distal tibiofibular syndesmosis (Lauge-Hanssen SER II and Weber B) with 2 mm or more fibular fracture displacement. The rationale for surgery for these ankle fractures is based on the notion of elevated intraarticular contact pressures with lateral displacement. To diagnose these injuries, we presumed that in patients with a fibular fracture with at least 2 mm fracture displacement, the lateral malleolus and talus have moved at least 2 mm in a lateral direction without medial displacement of the proximal fibula. We reviewed 55 adult patients treated operatively for a supination-external rotation II ankle fracture (2 mm or more fibular fracture displacement) between 1990 and 1998. On standard radiographs, distance from the tibia to the proximal fibula, distance from the tibia to the distal fibula, and displacement at the level of the fibular fracture were measured. These distances were compared preoperatively and postoperatively. We concluded tibiotalar displacement cannot be reliably assessed at the level of the fracture. Based on this and other studies, we believe there is little evidence to perform open reduction and internal fixation of supination-external rotation II ankle fractures.     

Displaced Salter-Harris Type I Distal Fibula Fractures: Two Case Reports and a Review of the Literature

Salter-Harris type I (SH-I) fractures of the distal fibula are commonly encountered in pediatric orthopedics. We describe 2 unique cases of adolescents with completely displaced SH-I distal fibula fractures that were treated operatively. In the first case, a closed reduction attempt failed and the patient required open reduction and internal fixation of the distal fibula and syndesmosis. The syndesmotic ligaments were avulsed from the distal fibular metaphysis. In the second case, closed reduction of the distal fibula fracture was partially successful, but anatomic reduction could not be achieved without open reduction. The distal fibula fracture was fixed with an intramedullary screw. We believe this pattern of injury represents a variant of the adolescent transitional ankle fracture. Because the distal tibial physes were nearing complete closure in these patients, the energy propagated through the distal fibular physis. To the best of our knowledge, this combination of injuries has not been previously reported. This type of physeal fracture raises concern for premature physeal closure, fibular growth disturbance, syndesmotic instability, and medial (deltoid ligament) injury. Both patients had excellent outcomes after anatomic reduction and fixation of the displaced SH-I distal fibula fractures at 1 and 6 years of follow up, respectively.     

A Pilon Fracture With Fibular Head Dislocation Treated With the Use of 3D Preoperative Planning: A Case Report and Literature Review

Pilon fractures with intact fibula have been associated with low-energy trauma. However, the compression force onto the ankle joint can damage the tibiofibular linkage as in a Maisonneuve fracture. Herein, we describe a case of a patient who had a pilon fracture (AO type 43 C3.2) without a fibular fracture. Three-dimensional preoperative simulation by reduction with the surface registration technique was performed as the fibular length was intact and there was no reference for the tibial length. The preoperative simulation revealed superior fibular head dislocation and shortening of the distal tibia. After emergency external fixation on the day of arrival, a 2-staged surgery was performed. During the first operation, the fibular head was reduced and the tibial posterolateral fragment was fixed to restore the tibia length. During the second operation, medial and anterolateral fragments were fixed in order to reduce joint surface of the distal tibia. In general, proximal fibular head fractures are easily overlooked. In the case of pilon fractures with severe length shortening of the tibia without a fibular fracture, a proximal tibiofibular injury should be suspected.     

螺钉固定与Tight-rope固定治疗下胫腓前联合损伤的初步有限元分析

目的 :建立下胫腓前联合损伤(anterior inferior tibiofibular syndesmosis injuries,AITSI)螺钉固定及Tightrope固定(TR)模型,比较其受力及位移情况,为临床诊治提供依据。方法 :选取1例正常人的踝关节CT图像建立3D模型。然后建立AITSI损伤模型,对损伤模型置入螺钉得到螺钉固定模型,使用Tight-rope固定得到TR模型。分析各模型单脚站立时的中立位、踝关节内旋以及外旋3种受力情况,观察胫腓骨及距骨关节面应力变化,以及胫腓骨远端位移情况。结果:AITSI导致胫腓骨及距骨关节面受力增加,胫腓骨位移增加。使用螺钉固定及TR均能有效减少AITSI导致的胫腓骨远端过度位移,但在螺钉固定模型中,胫腓骨位移明显小于正常模型,且胫腓骨远端及距骨关节面受力增大,螺钉受力集中。螺钉固定模型中的胫骨及腓骨最大受力为TR模型的1.3倍以上,距骨关节面接触力为1.8倍,螺钉固定模型中下胫腓前韧带胫骨附着点位移约为正常模型的0.6倍,而TR模型中该数据约为正常模型的1.1倍,但TR对于腓骨位移控制欠佳。结论:严重的下胫腓前联合损伤将改变踝关节受力及位移情况,应该行内固定治疗。下胫腓联合螺钉及TR都能有效地治疗下胫腓前联合分离,Tight-rope固定相较于螺钉固定在骨骼受力、踝关节微动及内固定物断裂方面具有优势,但存在腓骨旋转控制欠佳的劣势。伴有Weber C型踝关节骨折以及肥胖的患者更适合螺钉固定。     

Ankle injuries in distal tibial spiral shaft fractures: results from an institutional change in imaging protocol

Introduction

Posterior malleolus and other articular ankle injuries are known to concomitantly occur with tibial shaft fractures, especially spiral fractures of the distal one-third diaphysis. Due to our heightened awareness of this combined injury, our department instituted a new preoperative ankle imaging protocol for all distal one-third spiral tibia shaft fractures. The purpose of this study was to evaluate the effectiveness of an imaging protocol involving radiographs, CT and magnetic resonance imaging (MRI) in a distal one-third spiral tibia fracture cohort.

Materials and methods

All operatively treated patients with a spiral distal one-third tibial shaft fracture from February 2012 to March 2013 underwent a standardized ankle imaging protocol. Patients had preoperative orthogonal ankle radiographs as well as a CT scan of the tibia that included the ankle. All ankle imaging was scrutinized for evidence of an ankle injury. If no ankle fracture was identified, patients would then undergo an ankle MRI.

Results

Twenty-five patients met the inclusion and exclusion criteria for this study. Concomitant osseous ankle injuries were identified by radiograph and CT in 56 % (14/25) of cases. The remaining 44 % (11/25) of patients had no evidence of a combined injury by radiograph or CT and therefore underwent an MRI. Of the MRI cohort, 64 % (7/11) were found to have an occult ankle fracture. The overall incidence of a combined injury using our protocol was 84 % (21/25). Identification of an occult injury led to a change in management for all of these patients.

Conclusions

Concomitant ipsilateral ankle and distal one-third spiral tibial shaft fractures are more common than previously reported. Utilizing a new imaging protocol, we found that the incidence of this combined injury was 84 %. Recognition of the ankle fracture component in this tibial shaft cohort can be important as it may alter the surgical plan and postoperative management.     

Fibular nonunion and equinovarus deformity secondary to posterior tibial tendon incarceration in the syndesmosis: a case report after a bimalleolar fracture-dislocation.

A 39-year-old woman sustained a grade II open bimalleolar fracture-dislocation of the left ankle. Six months after an ORIF of these fractures was performed, she presented with a nonunion of the distal fibula fracture and with a fixed hindfoot equinovarus and forefoot adduction deformity. At surgery for repair of the fibular nonunion, the posterior tibial tendon (PTT) was found to be entrapped in the posterior tibiotalar joint, with a portion of the tendon interposed between the tibia and the fibula in the area of the posterior syndesmosis. After extrication of the PTT, the hindfoot varus and forefoot adduction deformity were corrected. To our knowledge, this is the first case report in the English literature of a missed PTT syndesmotic entrapment that resulted in a fibular nonunion and in a fixed foot deformity after an open bimalleolar ankle fracture dislocation.     

胫骨下1/3螺旋形骨折合并隐匿性后踝骨折的治疗分析

目的探讨胫骨下1/3螺旋形骨折合并隐匿性后踝骨折的发生原因、受伤机制和治疗方案。方法于2005年2月至2011年6月收治胫骨下1/3螺旋形骨折22例,其中有显性后踝骨折6例。采用胫骨髓内钉固定8例,胫骨下端前侧钢板1例,胫骨前外侧钢板13例;2例腓骨中段骨折采用重建钢板固定,其余腓骨均未固定。结果术中有4例患者在应用前外侧钢板固定最远端时发现隐匿性后踝骨折并移位,1例采用胫骨髓内钉的患者术后1个月复查X线片发现隐匿性后踝骨折伴移位。结论术前没有CT、MRI检查能够确诊后踝骨折类型和大小时,胫骨下端前外侧钢板可作为首选的内固定。     

Altered fibular growth patterns after tibiofibular synostosis in children

BACKGROUND: Iatrogenic synostosis of the tibia and fibula following an operation on the leg in a child has been reported rarely in the literature, and the effects of this complication on future growth, alignment, and function are not known. This is a retrospective case series, from one institution, of crossunions of the distal parts of the tibia and fibula complicating operations on the leg in children. The purpose is to alert surgeons to this possible complication. METHODS: The senior author identified eight cases of iatrogenic tibiofibular synostosis seen in children since 1985. The patients had various diagnoses and were from the practices of four pediatric orthopaedic surgeons. Synostosis developed in six patients after osteotomies of the distal parts of the tibia and fibula, in one after internal fixation of distal tibial and fibular metaphyseal fractures through a single incision, and in one after posterior transfer of the anterior tibialis tendon through the interosseous membrane combined with peroneus brevis transfer to the calcaneus. Medical records were reviewed, and preoperative and follow-up radiographs were analyzed for changes in the relative positions of the proximal and distal tibial and fibular physes and in the alignment of the ankle. RESULTS: Five patients were symptomatic after crossunion; they presented with prominence of the proximal part of the fibula, ankle deformity, or ankle pain. Three patients were asymptomatic, and a synostosis was identified on routine follow-up radiographs. Intraoperative technical errors caused two of the crossunions; the cause of the others was unknown. Following tibiofibular synostosis, growth disturbances were noted radiographically in every patient. The normal growth pattern of distal migration of the fibula relative to the tibia was reversed, resulting in a decreased distance between the proximal physes of the tibia and fibula as well as proximal migration of the distal fibular physis relative to the distal part of the tibia. Shortening of the lateral malleolus led to greater valgus alignment of the ankle. CONCLUSIONS: Tibiofibular synostosis can complicate an operation on the leg in a child. After crossunion, the normal distal movement of the fibula relative to the tibia is disrupted, resulting in shortening of the lateral malleolus and ankle valgus as well as prominence of the fibular head at the knee. The synostosis also interferes with the normal motion that occurs between the tibia and fibula with weight-bearing, potentially leading to ankle pain.     

手术治疗外展外旋力所致踝关节骨折

手术治疗外展外旋力引起的踝关节骨折３５例，平均随访２年半，满意率为８８．６％。效果不佳者与软组织损伤严重和关节软骨受损有关。恢复腓骨的长度对防止距骨移位与倾斜十分重要。用钢板固定外踝时要使其下端适应腓骨下段的外翻角。下胫腓联合不论是完全还是不全分离，都应用螺钉固定，以增加踝关节稳定性，早期练习活动。三角韧带断裂时，只要腓骨解剖复位与坚强固定，三角韧带可不予修复。对小于胫骨远端关节面２５％的后踝骨折可不予处理。     

Fracture of the lower leg with involvement of the posterior malleolus; a neglected combination?

In 17 of 148 fractures of the leg (11.5 per cent) we found an isolated fracture of the posterior malleolus of the tibia as a sign of associated injury of the ankle joint. In two cases there was even disruption of the anterior syndesmosis. All fractures of the tibia were oblique and closed without severe soft tissue injury and caused by a rotational force with low energy. In fracture of the leg of this specific type a radiological examination of the ankle joint in search for a posterior malleolar fracture is needed. If present, instability of the distal tibio-fibular joint must be excluded.     

Biomechanical Analysis of a Novel Syndesmotic Plate Compared With Traditional Screw and Suture Button Fixation

Many lateral malleolus fractures have been found to have syndesmosis injuries after anatomic reduction. The main methods for the treatment of syndesmosis injuries are screw fixation and suture-button flexible fixations. In pursuit of innovation, we have designed a novel syndesmotic plate (NSP) for simultaneous fixation of lateral malleolus fractures and distal tibiofibular syndesmosis injuries. The purpose of this study is to compare the biomechanical characteristics of the NSP to syndesmotic screw and suture-button fixations. Twelve adult cadaveric specimens were used in this experiment. Axial loading as well as rotation torque were applied in 3 different ankle positions: neutral, dorsiflexion, and plantarflexion. After the initial specimens were tested, they were made into a pronation-abduction III fracture model as described by Lauge-Hansen. Subsequently, the specimens were fixed sequentially using a distal fibular anatomic locking plate (DFALP) combined with syndesmotic screws, DFALP combined with suture button, and NSP. Then the above tests were repeated. The syndesmotic displacement and the strain of the tibia and fibula were recorded during the experiment. In most cases, the displacements and strains of the NSP group and the screw group were smaller than the suture button groups and the native (SBGAN) (p < .05), and the displacements and strains of the NSP group were also slightly smaller than the screw group in most cases, and there was no significant difference between the 2 groups. The NSP we developed has a fixed strength no less than the traditional syndesmotic screw fixation. This provides us a new idea for the treatment of distal tibiofibular syndesmosis injuries.     

A computed tomography evaluation of two hundred normal ankles,to ascertain what anatomical landmarks to use when compressing or placing an ankle syndesmosis screw

Classical AO teaching recommends that a syndesmosis screw should be inserted at 25–30 degrees to the coronal plane of the ankle. Accurately judging the 25/30 degree angle can be difficult, resulting in poor operative reduction of syndesmosis injuries.The CT scans of 200 normal ankles were retrospectively examined. The centroid of the fibula and tibia in the axial plane 15 mm proximal to the talar dome was calculated. A force vector between the centroid of the fibula and the tibia in the axial plane should not displace the fibula relative to the tibia when surfaces are parallel. Therefore, a line connecting the two centroids was postulated to be the ideal syndesmosis line. This line was shown to pass through the fibula within 2.5 mm of the lateral cortical apex of the fibula and the anterior half of the medial malleolus in 100% of the ankles studied.The results support the concept that in the operatively reduced syndesmosis, the anterior half of the medial malleolus can be used as a reliable guide for aiming the syndesmosis drill hole, provided that the fibular entry point is at/or adjacent to the lateral fibular apex. The screw should also remain parallel to the tibial plafond in the coronal plane.     

Distal tibial metaphyseal fractures: the role of fibular fixation

Distal tibial extra-articular fractures are often a result of complex high-energy trauma, which commonly involves associated fibular fractures and soft tissue injury. The goal of tibial fixation is to maximise fracture stability without increasing soft tissue morbidity from surgical intervention. The role of adjunctive fibular fixation in distal tibial metaphyseal fractures has been controversial; although fibular fixation has been shown to improve stability of distal tibial fractures, there has been increased potential for soft tissue-related complications and a delay to tibial fracture healing. Adjunctive fixation of concomitant fibular fractures without associated syndesmotic or ankle pathology is not necessary in surgically stabilised extra-articular metaphyseal fractures of the distal tibia.     

To fix or not to fix? The role of fibular fixation in distal shaft fractures of the leg

Background

The role of stabilisation of the fibula in distal two-bone fractures of the leg is controversial. Some studies indicate the need for fibular stabilisation in 43 AO fractures, but few studies consider the role of the fibula in 42 AO fractures. The aim of the current paper is to explain the role of stabilisation of the fibula in 42 AO fractures, correlating the rates of healing and non-union between patients with and without fibula fixation.

Materials and methods

A total of 60 patients with 42 AO (distal) shaft fracture of the tibia with associated fracture of the fibula were selected. Patients were divided into two groups according to whether or not the fibula was fixed: Group I (n = 26) comprised patients who had their fibula fixed while Group II (n = 34) comprised patients who did not. The fibular fracture was classified according to the AO and related to the level of the tibial fracture. Other parameters examined were the union rate of the two groups correlated to the fracture pattern and position of the fibular fracture; the demographic data, such as age and gender; the presence of an open fracture, and the type of tibial fixation device used (nail or plate).

Results

None of the parameters considered (open injury, AO classification, device used and level of the fibular fracture relative to the tibial) were shown to have an influence on the development of a non-union.

Conclusion

This study showed a higher non-union rate when the fracture of the tibia and fibula were at the same level, the tibia was fixed with a bridging plate and the fibula left untouched. For this reason, we recommend fibular fixation in all 42 distal fractures when both fractures lie on the same plane and the tibial fracture is relatively stabilised.     

一种特殊类型的Maisonneuve损伤的诊断和治疗

目的报道一种特殊类型的Maisonneuve损伤的诊断和治疗效果。方法回顾性分析首都医科大学附属北京朝阳医院骨科自2015年1月至2019年7月收治的4例Maisonneuve损伤患者资料。男3例,女1例;年龄34~61岁,平均45.3岁;患者均为闭合性损伤。所有患者初始X线片表现为踝关节后脱位,手法复位后复查X线及CT显示复位良好无合并踝关节骨折,故急诊漏诊,门诊复查后显示下胫腓联合分离。所有患者均采用恢复腓骨长度、固定下胫腓联合及修复三角韧带的方法治疗。术后12个月采用美国足踝外科协会(AOFAS)的踝-后足评分评价患者术后功能。结果41例患者术后获12~14个月(平均12.7个月)随访。术后骨折愈合时间为110~185 d,平均149.3 d。术后未出现相关并发症,术后12个月AOFAS的踝-后足评分为82~96分(平均90.5分);其中优3例,良1例。结论临床表现为踝关节后脱位且不伴有明显踝关节骨折的Maisonneuve损伤临床上易漏诊,对单纯踝关节后脱位的患者复位后结合体格检查需要拍摄胫腓骨全长X线片明确诊断。一旦确诊,需行手术治疗。通过修复踝关节三角韧带及稳定下胫腓联合的方法可以达到满意的疗效。     

Incidence of Chondral and Osteochondral Lesions in Ankle Fracture Patients Identified With Ankle Arthroscopy Following Rotational Ankle Fracture: A Systematic Review

A systematic literature search was performed using the PubMed, MEDLINE, and the Cochrane Library databases according to the Preferred Reporting Items for Systematic review and Meta-Analyses guidelines on May 20, 2019. The keywords used were: ankle, distal tibia, distal fibula, fracture, arthroscopic, cartilage, and chondral. The objective of this study is to systematically review the characterization of intra-articular chondral injuries of the talus, tibial plafond, medial malleolus, and lateral malleolus in patients who undergo ankle arthroscopy following ankle fracture. Studies evaluating the incidence of chondral lesions at the time of arthroscopy for ankle fractures within any timeframe were included. The incidence of intra-articular chondral lesions was recorded, the location within the ankle, ankle fracture type, time of arthroscopy, characterization of chondral injury, complications, and outcome if available. Fifteen studies with 1355 ankle fractures were included. About 738 demonstrated evidence of chondral or osteochondral lesion (54.5%). Statistical analyses were carried out with statistical software package SPSS 24.0 (SPSS, Chicago, IL). We compared incidence rates of chondral injury based on Weber classification, malleolar fracture type, and Lauge-Hansen classification, using Pearson chi-square test. For all analyses, p < .05 was considered statistically significant. We found a high incidence of intra-articular chondral lesion in the setting of ankle fractures as demonstrated by arthroscopy.     

胫骨pilon骨折受伤机制的有限元分析

目的 探讨胫骨pilon骨折发生过程中胫腓骨及远端关节面的应力分布规律。方法 选择1名健康男性志愿者建立胫腓骨及距骨的三维有限元模型,根据骨折发生特点设定工况,在中立位、背伸、跖屈、内翻、外翻5种不同工况下从距骨远端向近端进行静力加载,并将模型与地面进行碰撞。结果 在静载荷下,中立位应力主要分布于踝间线以前的内踝、胫骨踝穴顶前缘及外踝,背仲位应力主要分布于外踝及胫骨踝穴顶前部,跖屈位应力分布于胫骨踝穴顶后部,内翻位应力主要分布于外踝关节面及胫骨踝穴顶外侧部,外翻位应力主要分布于外踝关节面。在碰撞情况下,中立位应力分布与静载荷下一致,背伸立应力主要分布于踝间线以前,跖屈位应力主要分布于胫骨踝穴顶之踝间线后部及外踝关节面,内翻立应力主要分布于胫骨踝穴顶外部及外踝,外翻位应力主要分布于内踝、外踝及踝间线前部。腓骨关节面存静载荷作用下均处于高应力分布状态,在碰撞过程中亦最早接受应力分布。结论 腓骨是胫骨pilon骨折发生中最早受累且受累较重的部位。胫腓骨远端关节面在骨折发生中存在4个主要应力分布区,此4个应力区向近端延伸为内、外、前、后4个柱。