Comparative Studies Of Computed Tomography Morphology Of Posterior Pilon Fracture And Posterior Malleolar Fracture

Distal tibial is constituted of cortical bone, cancellous bone and cartilage articularis, playing a role of increasing contact area of tibiotalar joint and reducing unit area pressure of tibiotalar joint[1]. Lateral and posterior malleolus and lower tibiofibula opisthodetic ligaments are stable structure maintaining joint stability and ankle normal condition[2]. Distal tibial fracture in the posterior joint is clinically common. Avulsion fracture associated with rotational load is a type of posterior malleolar fracture and can be classified according to the Lauge-Hansen system. The typical characteristic of such a fracture is that the fracture fragment is small and does not involve the joint layer, or involves it to a very small extent[3]. If accompanied by a vertical load, the fracture is a type of pilon fracture.There are debates on how to treat a distal tibial fracture in the posterior joint[4]. Most scholars support open reduction and internal fixation for posterior pilon fractures[5]. The surgical methods include indirect reduction by screwing from anterior to posterior, direct reduction by screwing from posterior to anterior and the use of a support plate[6]. With meta Plate is used recently, it is also used in operations of pilon fractures. In addition, different operative approaches and internal fixation methods are required for different fracture types[7]. As posterior pilon fractures often involve medial and lateral malleolus, conditions of medial and lateral malleolus fractures as well as sizes and locations of fractured part of posterior pilon should be considered for therapeutic regimen and operative approaches. Conservative therapies and surgical therapies can be selected according to fracture types and patients’conditions. Surgical therapies including operation methods with lateral approach, posteromedial approach, combination of lateral and posteromedial approaches, percutaneous anterolateral malleolus fixation with lag screws and others. Operation duration, internal fixation methods and protection of surrounding soft tissue all pose large impacts on prognosis[8、9]. However, a typical posterior malleolar fracture does not require surgery[3].Recently, there are multiple classification method for distal tibial fracture. Haraguchi etc[9] reported:Based on the CT images of the transverse planes, posterior malleolar fracture are classified as posterolateral-oblique type(type Ⅰ) and small-shell type (type Ⅱ). Yu GR etc[3] reported:by studying CT images, the PPFs are classified as posterolateral-oblique type(type Ⅰ), medial-extended single bone type (type Ⅱ) and medial-extended double bone type (type Ⅲ,including posteromedial and posterolateral fracture segments). The classification of type Ⅰ PPFs was in good agreement with the posterolateral-oblique type in the report by Haraguchi et al., whose injury mechanism is vertical load combined with rotational load, causing proximal displacement and collision with the joint layer of the posterior lateral Volkmann fracture fragment. The classification of types Ⅱ and Ⅲ PPF agreed well with the medial-extension type in the report by Haraguchi et al.[9],and this type has been further classified:a type Ⅱ PPF is a single posterior fragment fracture whose fracture line can be transverse or arch and extends to the posterior 1/3 or 1/2 of the medial malleolus or the anterior of the medial malleolus; a type Ⅲ PPF includes a posterolateral and posteromedial bone fragment. As syndesmotic disruption may occur with any of the 3 fracture types, Georg Klammer[10] ect suggested the use of a modifier to complete a classification to guide operative treatment strategy and classified posterior Pilon fractures into 3 primary categories by increasing degree of complexity in 2013:typeⅠfractures with a single medially based posterior malleolar fragment can be addressed through a posterolateral approach alone.Type Ⅱ fractures:in which the posterior fragment is split with possible posteromedial comminution, may require an additional medial or limited posteromedial approach to assist in reduction and fixation of the posteromedial fragment or separate medial malleolar fracture. In type Ⅲ fractures, the fracture line of the posterior malleolus exits the medial malleolus anterior to the posterior colliculus,and an additional anteromedial fragment is present. A medial approach is always necessary for reduction and fixation of the additional anteromedial fragment.However, the clinical imaging features of fracture of the two is lack of further research, especially the comparison of the characteristics of the two types of fracture imaging studies are much rarer, and this research is based on two different types of fractures in the CT image correlation measurement, helping clinical doctors from distinguishing posterior malleolar fracture to posterior Pilon fracture, and in the diagnosis and treatment of ankle fractures.This paper retrospectively analyzed the computed tomography (CT) images of 123 cases of distal tibial fracture in the posterior joint and classified them as posterior pilon fracture or posterior malleolar fracture. The measurements of relevant factors in the CT images for these two types of fractures can provide assistance to clinical doctors in distinguishing posterior pilon fracture from posterior malleolar fracture.Comparative Studies of Computer Tomography Morphology of Posterior Pilon Fracture and Posterior Malleolar FractureObjective:1. Between January 2010 and December 2014,123 cases of distal tibial fracture in the posterior joint in 123 subjects were collected in Nanfang Hospital, the affiliated hospital of Southern Medical University. The study was approved by the institutional review board of Psychosomatic Medicine of Southern Medical University, and all patients provided written informed consent. In every case, the postero-anterior and lateral radiographs, CT normal scans (the thickness of each CT scan was 0.625 mm-1 mm) were included to evaluate the fracture. The fractures were classified into cases for PPF, and PMF, etc.2. the following indexes were measured:1. angle a:the skew angle between the transverse plane major fracture line and the line connecting the bimalleolar axis-the line connecting the bimalleolar is the axis connecting the maximum tibia and fibula incisures; 2. angle β:the ratio between the area of the transverse plane of the fracture fragment and the total area of the tibia distal end; 3. FAR1:the skew angle between the sagittal plane fracture line and the horizontal line; and 4. FAR2:the ratio between the area of the sagittal plane of the fracture fragment and the total area of the tibia below the horizontal line at the apex of the fracture lines. The measured results were compared and analyzed.3. To compare morphological differences shown by computed tomography (CT) and provide help for the diagnosis and treatment of posterior pilon fracture fragments and posterior malleolar fracture fragments.Methods:1.123 cases of distal tibial fracture in the posterior joint in 123 subjects were collected in Nanfang Hospital, the affiliated hospital of Southern Medical University. The exclusion criteria are as follows:the fracture does not involve tibial posterior joints, or the subjects are aged below 18 or born with deformity of the ankle joints. In every case, the anterior and lateral images, CT normal scan and 3D reconstruction (the thickness of each CT scan was 0.625 mm-1 mm) were included to evaluate the fracture. Posterior pilon fracture and posterior malleolar fracture were thus classified according to the criteria. posterior malleolar fracture was classified according to the Lauge-Hansen system. Based on the above criteria,76 cases were classified as PPFs, of which 48 cases were male and 28 female,40 cases were left lateral and 36 right lateral, and the average age was 42.1 years (19-68); and 47 cases were classified as PMFs, of which 33 cases were male and 14 female,25 cases were left lateral and 22 right lateral, and the average age was 39.6 years (18-64).2. The CT plane with the largest measuring area of each fracture fragment was selected as the research plane (including the transverse and sagittal plane). Based on the shape of the transverse fracture line, the fractures were classified into cases of posterior pilon fracture and posterior malleolar fracture. The following characteristics indicate the presence of vertical load and therefore define PPF:the joint layer of the fractured fragment exhibits collision and compression, which also occur in the joint layer of the corresponding talus; the fracture fragment involves the joint layers of posterior malleoluses, is displaced proximally and forms steps; the fracture fragment can be extended to the posterior 1/3 or 1/2 of the medial malleolus or the anterior of the medial malleolus. The following characteristics indicate the presence of rotational load and therefore define PMF:the joint layers of the fracture fragment and talus do not show collision and compression; the fracture fragment does not involve the joint layer of posterior malleoluses; there is no direct connection between the fracture fragment and the medial malleolus fracture fragments.3. For each case, after the real area of the CT transverse plane and sagittal plane for the fracture fragment was measured, the CT layers with the largest measurement area in the fracture fragments were chosen as the planes to study. Based on the morphology of the fracture line on the transverse plane, the cases were classified into posterior pilon fractures and posterior malleolar fractures. The following indexes were measured:1. angle a:between posterior fracture line at transverse plane and bimalleolar axis; 2. FAR1:ratio of area of posterior ankle fracture fragment at transverse plane to total area of distal tibia; 3. angleβ:between posterior fracture line at sagittal plane and horizontal line; and 4. FAR2:ratio of area of posterior ankle fracture fragment at sagittal plane to total area of tibia under the horizontal plane of the top of the posterior ankle fracture line. The following parameters were measured:The measurements were obtained using Image-Pro Plus 6.0. Because of the full dislocation in one case of PPF, the fracture fragment was displaced clearly towards the lateral superior direction and was completely separated. This property affected the accuracy of measurement, and therefore, relevant parameters were not measured. There were 13 cases for which the CT images of the sagittal plane were not captured(PPF:7 cases, PMF:6 cases).4. The results were compared and analyzed. The adopted statistical methods were the independent two-sample t-test and one-way analysis of variance. The difference is considered statistically significant when p<0.05.Results:1. According to Yu GR etc.[3] report.Based on the CT images of the transverse planes, among the 76 cases of posterior pilon fracture,46 cases were posterolateral-oblique type(type Ⅰ), and 30 cases showed fracture lines extending to the medial, of which 10 cases were medial extending single fracture (Type Ⅱ), while the remaining 20 cases were medial extending double fracture (Type Ⅲ, including the posteromediall and posterolaterabone fragment)[3] Sixty-five cases were oblique fractures combined with the external malleolus and extended from the posterior superior to the anterior inferior direction; 10 cases were fractures involving the whole medial malleolus, and 1 case was a pure posterior pilon fracture. In 51.3%(39/76) of cases of posterior pilon fracture, posterior subluxation or dislocation of talus occurred (including 3 cases of full dislocation).2. With regard to Haraguchi etc.[9] report.Based on the CT images of the transverse planes, among the 47 cases of posterior malleolar fracture,35 cases were posterolateral-oblique type(typeⅠ), and 12 cases were small-shell type (typeⅡ). Thirty-three cases exhibited supination external rotation (21 cases of type I and 12 cases of type Ⅱ),8 cases exhibited pronation-external rotation (type Ⅰ), and 6 cases exhibited pronation-abduction (typeⅠ). In 8.5%(4/47) of cases of posterior malleolar fracture, lateral subluxation occurred, and no full dislocation was observed. 3. The skew angle a of both posterior pilon fractures and posterior malleolar fractures varied substantially and showed no statistical difference (P=0.18). The skew angleβ of posterior pilon fractures and posterior malleolar fractures remained constant at approximately 80° and showed a statistical difference:the skew angle β of posterior pilon fractures is larger than for posterior malleolar fractures (P=0.04). Forty-eight percent (36/75) of cases of posterior pilon fracture had FAR1≥25%,55.9%(38/68) cases of posterior pilon fracture had F AR2≥25%, and all cases of posterior malleolar fracture had both FAR1 and FAR2<25%. Comparison revealed that FAR1 was larger for posterior pilon fractures than for posterior malleolar fractures, and the difference was statistically significant (p=0.00). Similarly, FAR2 was larger for posterior pilon fractures than for posterior malleolar fractures, and the difference was statistically significant (p=0.00). The measured FAR1 values for type Ⅰ (45 cases), type Ⅱ (10 cases), and type Ⅲ (20 cases), Posterior pilon fractures were 18.9±11.6%,33.4±13. 1%　and 30.0±7.3%, respectively. FAR1 for type Ⅱand type Ⅲ posterior pilon fractures was larger than for type Ⅰ posterior pilon fractures, and the difference was statistically significant (p=0.00 and p=0.00). FAR1 for type Ⅱ posterior pilon fractures was not statistically significantly different from FAR1 for type Ⅲ posterior pilon fractures (p=0.42). The measured FAR2 values for type Ⅰ (41 cases), type Ⅱ (8 cases), and type Ⅲ(19 cases) posterior pilon fractures were 28.3±13.5%,28.1±5. 6% and 28.2±5.6%, respectively. No statistical difference was observed between type Ⅰ and type Ⅲ(P=0.95), between type Ⅱ and type Ⅲ(P=0.98), and between type Ⅰ and type Ⅲ (P=0.96). The measured FAR1 values for type I (35 cases) and typeⅡ (12 cases) posterior malleolar fractures were 7.6±2.8% and 4.8±3.8%, respectively. Comparison of these FAR1 values shows a statistically significant difference with a larger FAR1 for type I posterior malleolar fractures (P=0.01). The measured FAR2 values for type I (29 cases) and type Ⅱ (12 cases) posterior malleolar fractures were 16.0+4.6%% and 13.0±5.4%%, respectively. Comparison of these FAR2 values shows no statistical difference (P=0.07). Comparison of FAR1 for type Ⅰ posterior pilon fractures and type Ⅰ posterior malleolar fractures shows a statistically significant difference with larger FAR1 values for type Ⅰ posterior pilon fractures (P=0.00); FAR2 for type Ⅰ posterior pilon fracture and type Ⅰ posterior malleolar fracture shows a statistically significant difference with larger FAR2 values for type Ⅰ posterior pilon fractures (P=0.00). Twenty cases of type Ⅲ posterior pilon fracture included posteromedial and posterolateral bone fragments, whose transverse plane area ratios were 16.1±6.2% and 14.5±6.5%, respectively. The difference did not show statistical significance(P=0.43).Conclusion:1. The transverse fracture lines of posterior pilon fractures and posterior malleolar fractures are variable, and this result is likely directly related to the diversity of loads involved in distal tibial fractures in the posterior joint.2. The fracture line of the sagittal plane was basically vertical with respect to the ground, and the angle between the ground and compared with posterior malleolar fractures, Posterior pilon fractures is much larger, indicating that posterior pilon fracture are more relevant to the perpendicularity to the ground.3. Posterior pilon fractures have a higher risk of ankle joint subluxation or dislocation than posterior malleolar fractures.4. Posterior pilon fractures have significantly larger transverse and sagittal plane area ratios than posterior malleolar fractures.5. The transverse plane area ratios of type II and III posterior pilon fractures are larger than for type I posterior pilon fractures, while no difference was observed between type II and III posterior pilon fractures. The sagittal plane area ratios of type I, type II and III posterior pilon fractures are no different.6. The area of the transverse plane is larger for type I posterior malleolar fracture than for type II. The sagittal plane area ratios of type I, type II and III posterior malleolar fractures are no different.7. type I Posterior pilon fractures have significantly larger transverse and sagittal plane area ratios than type I posterior malleolar fractures.8. Twenty cases of type III posterior pilon fracture included posteromedial and posterolateral bone fragments, whose transverse plane area ratios were not diffirent.Comparison between Staged ORIF and EFLIF in Treatment of Pilon Fracture:A Systematic ReviewObjective:To analyze and compare the differences in curative effect between staged open reduction and internal fixation and external fixation with limited internal fixation by systematic review.Methods:Literatures about the effectiveness analysis of staged open reduction and internal fixation and external fixation with limited internal fixation, published from 2000 to 2014, were collected through database retrieval and manual search. The index words were " Pilon fracture, tibia fracture, staged ORIF, EFLIF, therapy". The evaluation indicators were set as soft tissue infection rate, osteomyelitis incidence rate, bone nonunion, malunion incidence rate and arthrodesis incidence rate. RevMan5.2 software was adopted to analyze the results and characteristics in the form of forest plots.Results:Six studies were included after the full text analysis. The results indicated that the soft tissue infection rate in Staged ORIF group was significantly lower than that of EFLIF group(Z=2.82, P=0.005). And there were no differences between the two groups respectively in osteomyelitis incidence rate(Z=0.97, P=0.33), bone nonunion(Z=0.48, P=0.63), malunion incidence rate(Z=1.86,P=0.06) and arthrodesis incidence rate(Z=1.46, P=0.14).Conclusion:The soft tissue infection rate was lower when the technique of staged open reduction and internal fixation was used. However, with respect to the overall curative effect, there was no obvious difference comparing with the method external fixation with limited internal fixation.