Basic And Clinical Study Of Spiral Fracture Of Low 1/3 Tibial Shaft Combined With Posterior Malleolar Fracture

Spiral fracture of low 1/3 tibia shaft combined with posterior malleolar fracture was a special complicated fracture. The posterior malleolar fracture usually present as occult fracture, which was negative in X-ray examination. So the rate of missed diagnosis was very high. The spatial resolution of MSCT and MR were higher than X-ray and they served as tools to detect posterior malleolar occult fracture. How to select imaging method to increase diagnosis accuracy was an important problem in clinic. Determining type and scale of fracture according to images could provide more detail information of fracture fragment, and reduce traumatic osteoarthritis that induced by inappropriate treatment. This study evaluated the imaging features and diagnosis value of tibia diaphyseal fracture in X-ray, CT and MRI, and provide imaging basis for clinical treatment.Spiral fracture of low 1/3 tibial shaft is often associated with posterior malleolar fracture, which is a special kind of combined injury. This combined injury often occurs in the sprain, a fall or other low-energy trauma. Its injury mechanism remains a hypothesis and there are only a few related biomechanical studis. Performing biomechanical study and exploring its injury mechanism with the use of specimens of lower extremities is helpful in understanding profoundly this combined injury and improving the quality of fracture reduction. Spiral fractures of distal third of the tibia are often associated with posterior malleolar fracture. When the posterior malleolar fractures occure, the functional reconvery of ankle joint will be poor. In some fractures, besides posterior malleolar fractures, other part of ankle joint may also involved in fractures, or comminuted or compressed distal tibial articular fractures may occure, which call for great attention in the management of such fractures. In the management of the spiral fractures of distal third of the tibia using intramedullary nail or plate, if the implant placed unproperly, it could make the non-displaced posteriror malleolar fracture displaced. In the rehabilitation exercises of the ankle joints, the unfixed posterior malleolar fractures may also become displaced. In such condision, conservative or operative fixation should be performed and even so, the ankle joint is an increased risk to sustain posttraumatic arthritis. Therefore, CT or MRI tests shohld be recommended in tibial spiral fractures where posterior malleolar fractures can't be diagnosed by X ray test. Classifying such combined injuries and making surgical plan based upon the severity of posterior malleolar is helpful to improve the outcome.Ankle fractures are common in orthopedic practice, among which as high as 25% are posterior malleolar fractures. It is generally believed that simple posterior fracture is a rare injury. The posterior malleolar fractures are often aossociated with medial malleolar fractures, lateral malleolar fractures as well as tibial and fibular fractures (proximal to lateral malleolar fractures). However, the large-sample epidemiological survey of posterior malleolar fractures ankle fractures is rare. Therefore it is necessary to conduct retrospectively epidemiological study on posterior malleolar fractures to in order to reveal its epidemiological characteristics and improve the treatment of posterior malleolar fractures. Part 1 Imaging Analysis of spiral fractures of distal third of the tibia Fracture with Posterior Malleolar FractureObjective: To evaluate the imaging features and diagnosis value of tibia diaphyseal fracture in X-ray, CT and MRI, and to provide the imaging basis for clinical treatment.Methods: One hundred and fifty-one patients with tibia spiral fracture were performed X-ray examination. 124 patients (98 male, 28 female; age range, 12–80 years; mean age, 39.9±16.7 years) with negative X-ray results underwent MSCT and MR imaging within a week after trauma. MSCT data were obtained with 0.7-mm-thick multiplanar reformations were performed in transverse, coronal, and sagittal planes relative to the tibia. 11 Imaging dataImages of X-ray, MSCT and MR were reviewed by two musculoskeletal radiologists in consensus. The contents including:1.1 The shape of tibia fracture and posterior malleolar fracture, and the relationship between them. Displace of the fracture was recorded. The size of fracture block of posterior malleolus was measured and its proportion to malleolus was calculated at axial CT images.1.2 MSCT and MR images were reviewed. To approximate the clinical situation, the readers were informed about the site of clinical symptoms. The readers distinguished between signs of a cortical and signs of a trabecular fracture. In addition, readers were asked to note any other signs, such as dislocation of ankle joint or fibula fracture.2 Criteria for occult posterior malleolar fracture:Criteria on MSCT images were the presence of a sharp lucent line within the trabecular bone pattern, a break in the continuity of the cortex, a sharp step in the cortex, or a dislocation of bone fragments.Criteria for a bone fracture on MR images included the presence of a cortical fracture line, a trabecular fracture line, or a combination of both. Such a fracture line had to be hyperintense on STIR and T2-weighted images and hypointense or hyperintense on T1-weighted images. Evidence of a zone of diffusely increased signal intensity on STIR images was interpreted as bone marrow edema but not as a manifest fracture.3 Statistical AnalysisData were analyzed with a statistical software package (SPSS 13.0). A binomial test was used to evaluate the significance of the differences between MR imaging and MSCT with regard to the detection of posterior malleolar fractures and cortical involvement at a P value of less than 0.5. Results: 126 (83.4%) in 151 tibia shaft fracture were found associated with posterior malleolar fracture. 99 (78.6%) posterior malleolar occult fracture were detected by MSCT and/or MRI.1 Imaging typing of tibia spiral fracture fracture combined with posterior malleolar occult fracture.Type A and type B were determined according to the association of tibia fracture and posterior malleolar fracture. Type A indicated fracture of tibia shaft and fracture of posterior malleolar were separate. Type B indicated that these two fractures were continued.Three scales were determined according to imaging features. Scale 1: Posterior malleolar fracture fragment was less than 25%, and no displacement occult fracture. Scale 2: Posterior malleolar fracture fragment was less than 25% with displacement, or posterior malleolar fracture fragment was larger than 25%. no ankle joint dislocation and/or fibula fracture was combined in this kind of patients. Scale 3: Posterior malleolar fracture fragment was larger than 25%, combined with ankle joint dislocation and/or fibula fracture. 91 cases in type A and 35 cases in type B were found. 59 cases in Scale 1, 48 cases in scale 2, 19 cases in scale 3 were determined.2 Detection of posterior malleolar occult fracture124 cases whose X-ray were negative were performed MSCT and MR examination. 99 cases among them were found posterior malleolar fracture. 78 cases (78.8%) involved cortex. 81 cases were detected by MSCT, while 99 were detected by MRI. The sensitivity of posterior malleolar occult fracture in MSCT was 81.8%, specificity was 100%, and accuracy was 85.5%. MRI resulted in 100% sensitivity, specificity and accuracy. For 78 cases with posterior malleolar occult fracture involved cortex, 78 cases cortex fracture were detected by MSCT, 51 cases by MRI. The sensitivity, specificity and accuracy in CT were 100%. The sensitivity of detection of cortex fracture in MRI was 65.4%, specificity was 100%, and accuracy was 72.7%.The sensitivity of posterior malleolar occult fracture in MR was higher than MSCT, however with no statistic significant.The sensitivity of cortex fracture in MSCT was significant higher than MR (p<0.05).Conclusion: 1. Tibia shaft fracture was often associated with posterior malleolar fracture with 83.4%. The incidence rate of posterior malleolar occult fracture was 78.6%.2. Only 19.8% posterior malleolar fracture combined with tibia shaft fracture was detect by X-ray. For tibia shaft fracture patients, even no posterior malleolar fracture was found by X-ray, MSCT or MR should be performed.3. MPR of MSCT can improve detection of occult fracture. MSCT has advantage in detecting cortex fracture, and discriminate pure trabecular fracture or cortex fracture, which was helpful for clinical treatment and prognosis. MR is sensitive in detecting bone marrow edema lesion combined with fracture.Part 2 Investigation of the injury mechanism of spiral fractures of distal third of the tibia with associated posterior malleolar fractureObjective: To investigate the injury mechanism of spiral fractures of distal third of the tibia with associated posterior malleolar fracture.Methods: 23 specimens of adult cnemis were collected, including 15 fresh amputated lower extremity and 8 antiseptic specimens soaked in formalin. Fracture of each specimen was excluded by CT and MRI scan. On the basis of the injury mechanism of spiral distal third tibial with associated posterior malleolar fracture, The specimens were fixed in the fixture using the self-curing denture acrylic to simulate the lower extremity in anteversion position and the ankle joint in neutral position, the lower extremity in upright position and ankle joint in plantar flexion position, the lower extremity in upright position and ankle joint in dorsal flexion position, and the lower extremity in upright position and ankle joint in plantar flexion position with the foot in pronate and varus position. The fixture was separately connected to the NWS-10000 torsion testing machine, BOSE biomechanical testing machine and CSS-44020 bio-mechanical testing machine. The NWS-10000 torsion testing machine offered external rotation or internal rotation forces until tibia fractured. The BOSE biomechanical testing machine provided different vertical loads and 50NM torquemoment at the same time. The CSS-44020 biomechanical testing machine provided vertical loads with rotation forces offered artificially. After the test, the specimens were scanned by CT and MRI to examine whether the spiral fractures of distal third of the tibia with associated posterior malleolar fracture occured.Results: In the specimens tested on the NWS-10000 torsion testing machine, tibial fractures occurred when the rotating torquemoment increases to 72-107NM. Under internal-rotation torquemoment, the spiral fractures of distal third of the tibia run from lareral-inferior to medial-superior. Under external-rotation torquemoment, the spiral fractures of distal third of the tibia run from medial-inferior to lateral-superior and one corrosion specimen sustained posterior malleolar fracture simultaneously. In the specimens tested on the BOSE biomechanical testing machine, specimens were separately fixed simulating the lower extremity in anteversion position and the ankle joint in neutral position or the lower extremity in upright position and ankle joint in plantar flexion position. The specimens were offered vertical load and 50NM rotation torquemoment simultaneously. In this group, no spiral fractures of distal tibia occurred. One specimen sustained comminuted distal tibial fracture due to violent vertical load and the other specimens sustained subluxation or dislocation of ankle joints. In the group tested on the the CSS-44020 biomechanical testing machine, specimens were separately fixed to simulate the lower extremity in upright position and ankle joint in plantar flexion position with the foot in pronated- or supine- varus position. Ankle dislocation was found in a specimen when the external rotation force acts on the proximal cnemis. Dual spiral tibial fractures were noted in 2 specimens when the rotating force acts directly on both proximal and distal ends of the tibia. But no posterior malleolar fracture occurs.Conclusions: The biomechanical study verified that spiral fractures of distal third of the tibia can occur when the external rotation force acts on the proximal cnemis and the fracture line is from medial-inferior to lateral-superior. Posterior malleolar fracture were noted in 2 specimens, one corrosion specimen in upright position and ankle joint in plantar flexion position without vertical load and one fresh specimen in anteversion position and the ankle joint in neutral position under vertical load. However, this can't be reproduced in other specimens.Part 3 The clinical classification and treatment of spiral fractures of distal third of the tibia with associated posterior malleolar fractures.Objective: This study aims to investigate the injury characteristics of spiral fractures of distal third of the tibia with associated postwrior malleolar fractures, to measure the measurement the posterior malleolar fracture fragment, to classify the combined injury and study the efficacy of the surgical plan based upon the new injury classification.Methods: From July 2007 to June 2009 the data of tibial shaft fractures with associated posterior malleolar fractures were collected in our hospitl, which were analysed according to AO classification of fracture type and the new classificaiton referencing the severity of posterior malleolar fractures. The height, width and length of the fragment of posterior malleolar fracture were measured with the application of measurement software in CT and MRI. The ratio between the width of the posterior malleolar fragment and the width of the distal tibial articular surface were measured in the lateral radiograph and saggital CT or MRI images using the AUTOCAD2004. The relationship between the width, length and height of the fragment of posterior malleolar fracture were analysed. The combined injury can be classified into type A and type B injury referencing whether tibial shaft fracture runs directly to the posterior malleolus. Type B injury is often combined with distal tibial comminuted or compressed articular fractures and fractures of other parts of the ankle joint. Referencing the new classification, surgical plans were made to guide the management of the combined injury. The implants and surgeries applied in the treatment of tibial and fibular fractures with associated posterior malleolar fracutres were recorded and analysed. At regular postoperative follow-ups, radiological examinations were carried out and the funcional recovery of ankle joint were eveluated with the use of visual analogue score(VAS) and AOFAS Ankle-Hindfoot Scale.Results: There were 126 patients including 98 males and 28 female with the age of 39.9±16.7 years old in the study. There were 51 left and 75 right fractures. The majority of the patients were injured in falls, sprains or traffic accidents. 27 posterior malleolar fractures were diagnosed with radiograph, 82 with CT scans and 17 with MRI scans. The fracture pattern includes 17 gradeⅠinjuries, 82 gradeⅡinjuries, 19 gradeⅢinjuries and 8 gradeⅣinjuries. According to AO classification of fracture, the group consists of 104 cases of 42-type A fractures, 21 cases of 42-type B fractures and 1 cases of 42-type C fractures. The group included 119 cases of 43-type B fractures and 7 cases of 43-type C fractures. On the basis of the new classificaiton of the combined injuries, there were 91 cases of type A injuries, in which tibial shaft fractures and the posterior malleolar fracture were two separate fractures, and 35 cases of type B injuries. In type B injuries, besides posterior malleolar fractures, there were 2 distal tibial articular comminuted fractures, 4 distal tibial articular compressed fractures and 8 distal tibial articular comminuted-compressed fractures, 9 cases of ankle dislocation, 3 cases of subluxation of ankle joint, 6 medial malleolar fracture and 3 lateral malleolar fractures. There wre also 112 fibular fractures in the group. The measurements demonstrated that the average length of posterior malleolar fracture was 9.9 mm(range, 5.8-27.4mm), the average width was 13.2mm(range, 11.1 -39.5mm) and average height was 28.5mm (9.6-48.3mm). The ratio between the width of the posterior malleolar fracture and the distal tibial articular surface was 0.36±0.14(0.07-0.61). Manipulative reduction and cast immobilization were performed in two patients and surgeries were carried out in the other 124 patients. Among type A injuries, one tibial shaft fracture was treated with external fixators, 78 with intramedullary nailing and and 10 with plate fixation; one posterior malleolar fractures were managed with plate, 6 with Kirschner wires, 11 with cannulated screws, 17 with lag screws. Among type B injuries, 2 tibial shaft fractures were fixed with external fixators and 33 with plates; 4 posterior malleolar fractures were managed with plates and 24 with lag screws. 89 patients were followed up at 12 months postoperatively. The VAS score on fracture pain was 0.1±1.1 (range, 0-4). The VAS score on active pain of the ankle joint was 0.2±1.5 (range, 0-5) and that on weight-bearing walking pain was 0.5±1.1 (range, 0-7). The AOFAS Ankle-Hindfoot Scale was 86.7±9.6 (range, 58-98).Conclusion: This study revealed the injury features of tibial shaft fracture with associated posterior malleolar fractures of our hospital. The combined injury can be classified into type A and type B injury referencing whether tibial shaft fracture runs directly to the posterior malleolus. Type B injury is often combined with distal tibial comminuted or compressed articular fractures and fractures of other parts of the ankle joint. The new classification can be used to guide the management of the combined injury with high union rate of the fractures and satisfactory functional recovery of ankle joint.Part 4 The epidemiological analysis of posterior malleolar fracture in Hebei Orthopedic HospitalObjective: To investigate the epidemiological features of patients with posterior malleolar fracture treated in our hospital between January 2007 and December 2009.Methods: The data of patients with posterior malleolar fracture treated in our hospital from January 2007 to December 2009 are collected through the PACS system and case reports checking system and analyzed. The issues include gender, age, injuried sites, the features of the combined medial malleolar fractures, lateral malleolar fractures, tibial fractures and fibular fractures.Results: 566 patients with posterior malleolar fracture treated in our hospital during three years were included in the retrospective study. There are more men than wonem in the group. The men aged 31-40 years old are at high risk to sustain this fracture and the women aged 51-60 years old are at high risk. The left fractures is more than the right ones and bilateral fractures are the least. There are 59 cases with simple posterior malleolar fractures and 507 patients who sustaine other combined injuries. Among the 507 cases, the ipsilateral fibular fractures were the most common and other combined fractures or dislocations are medial malleolar fractures, lateral malleolar fractures, tibial fractures, dislocations of the ankle joint, talar fractures, calcaneal fractures, anterior malleolar fractures and metatarsal fractures. 294 cases with posterior malleolar fractures are with associated tibial or fibular fractures, including 154 tibial fractures, 85 tibial-fibula fractures and 55 fibular fractures. The simple posterior malleolar fractures are often combined with tibial-fibular fractures. The posterior and medial malleolus fractures are often combined with fibular fractures. The posterior and lateral malleolus fractures are often combined with tibial fractures. Low-energy trauma such as fall and sprain is the major cause of injury. 467 patients were admitted to our hospital including 298 males and 169 females with an average age of 40.1 years old. The major causes of injury are sprains, traffic accidents and falls. 18 patients combined with injuries of soft tissue, blood vessels and nerves. Open reduction and internal fixation is the main treatment algorism.Conclusion: This investigation revealed the epidemiological features of posterior malleolar fractures of our hospital which will help to understand the seriousness and complexity of the posterior malleolar fractures.