Ankle Fractures In Adolescents:Clinical Evaluation Of The Three-dimensional CT And Treatment Strategy

Part Ⅰ Closed reduction with cast and open reduction and internal fixation for displaced Salter-Harris type Ⅱ distal tibial physeal fractures in childrenObject:The treatment for displaced Salter-Harris(S-H)Ⅱ fractures of the distal tibia remains controversial.The purpose of this study was to evaluate the efficiency of the treatment by closed reduction with cast and open reduction and internal fixation(ORIF)and to identify the risk factors for the premature physeal closure(PPC)of the distal tibia.Methods:The charts and radiograph of patients with S-H Ⅱ fractures of the distal tibia with displacement greater than 3 mm between 2012 and 2020 were reviewed.The mechanism of injury was classified according to the Dias-Tachdjian system.Closed reduction with cast and ORIF were performed.The periosteum entrapped into the metaphsis,the healing time,PPC,infection of the incision and the injury of the nerve were documented.The period of following-up was a minimum of 4 months.Contralateral ankle radiograph or computed tomography(CT)were obtained if there was any evidence of PPC.Any angular deformity of the ankle was recorded.Results:Fifteen patients were included in group of closed reduction with cast,85 in group with ORIF.There were no difference in age,gender,the injured side,the amount of the initial displacement and the mechanism of the injury.The rate of the associated fibular fracture in group with ORIF was highest.The mean interval between the injury and operation was 3.7days.The interposed periosteum was detected in all cases treated by open reduction.The bones were healed between 6 and 8 weeks and there were no re-displacement in all cases.The rate of PPC was 29.4%in group with ORIF and two patients with varus deformities were suffered from pronation-eversion-external rotation(PER)force.Patient age,gender,injured side,mechanism of injury,amount of the initial displacement,interval from injury to surgery,or energy of injury did not affect the rate of PPC significantly.The rate of PPC was significantly greater in patients with associated fibular fracture than those with intact fibular(P=0.005).Conclusions:Closed reduction with cast and ORIF are effective choices for displaced S-H Ⅱ distal tibial physeal fractures.The entrapped periosteum can be removed after open reduction.The rate of PPC is not decreased after the entrapped periosteum was removed.Angular deformity following the PPC is more common in PER injuries.The presence of concurrent fibula fracture was significantly associated with PPC.Part Ⅱ Characteristics of supination-external rotation type S-H Ⅱ ankle fractures in CTObject:To evaluate the supination-external rotation type(SER)S-H Ⅱ ankle fractures by depicting in CT to improve the ability of understanding the given fractures and analyze the features of the associated fibular fractures to further determine the mechanism of the injury.Methods:The common radiograph and CT of patients with S-H Ⅱ fractures of the distal tibia between 2015 and 2019 were reviewed in our institution.The mechanism of injury was classified according to the Dias-Tachdjian system.Patients suffered from SER injury were included.The angle between the anterior line of the distal tibia 5-10mm proximal to the physis and the fracture line were measured in the axial CT views.And the distance of the metaphyseal Thurston-Holland(TH)fragment was measured in the saggital CT views.In presence of the fibular fracture,the fracture pattern was classified based on the location and the morphology of the fracture line.The correlation of the upper limits between the fibular fracture and the TH fragment was classified.Results:A total of 79 SER S-H Ⅱ ankle fractures with CT scans were identified in 79 children,27 girls and 52 boys.There were forty-five right and thirty-four left ankle fractures.The mean age of these patients was 12.2 years.In 35 cases the stage 1 was present and the stage 2 was present in 44 cases based on the Dias-Tachdjian staging for SER injury.In the axial CT,the metaphyseal fragment was rotational posterolaterally in all cases.The lateral cortex was fully fractured in all cases.The mean angle between the fracture line and the anterior distal tibia line was 11.2 degrees.Medial cortical bone was fully fractured in one case and 20 cases,in stage 1 and stage 2,respectively.There was significantly difference(P=0.001).In the saggital CT view,the mean length of TH fragment was 35.3mm.The length of TH fragment was 35.0mm,35.5mm,in stage 1 and stage 2,respectively.There was no significantly difference.The upper part of the fibular fracture line was located at the same level as that of the TH fragment in 27 patients and higher than that in 17,In 44 cases with associated fibular fracture,forty were in the distal metaphysis with oblique fracture line and being plantar flexion in 3D CT and other 4 in the distal diaphysis with spiral fracture line.Conclusions:For SER S-H Ⅱ ankle fractures,the medial tibial cortex bone intact or not and the direction of the fracture plane can be shown in axial CT scans to determine the stability of the fracture and to help to make the appropriate preoperative plan in presence of the screws.In addition to the external rotation force for SER S-H Ⅱ ankle fractures,there may be plantar flexion force based on the fibular morphology as shown in 3D CT.Part Ⅲ Triplane fractures in adolescents:characteristics in CT and the managementObject:To evaluate the triplane fracture in adolescents by depicting in CT and investigate the treatment to improve the ability of understanding the given fractures.Methods:The charts and CT of patients with triplane fracture between 2015 and 2020 were reviewed.The fracture pattern,the number of fragments in axial CT view,the angle between the anterior line of the distal tibia 5-10mm proximal to the physis and the fracture line,the concurrent fibular fracture,the interval between injury and operation,the method of treatment and the follow-up were recorded.Patients were followed up for a minimum of six months.The healing time,infection of the incision,injury of the nerve,PPC were documented during the following-up.Contralateral ankle radiograph or CT were obtained if there was any evidence of PPC.Any angular deformity of the ankle was recorded.The function of the ankle was evaluated according to the modified Weber system.Results:We identified 96 triplane fractures with available CT scans between 2015 and 2020,28 girls and 68 boys.There were 42 left and 54 right ankle fractures.The mean age of these patients was 13.2 years.Girls were found to suffer triplane fractures at a younger age than boys(12.3 years,13.6 years,respectively,P=0.001).The two-part type of fracture with medial epiphyseal extension from its anterior aspect occurred in 85 cases.These 86 cases included all 55 intramalleolar fractures.The three-part type of fracture was occurred in 11 cases,including one case with Marmor-equivalent fracture and one with Peiró type fracture.The age difference between the two-part and three-part fractures was not statistically significant(13.3 years,13.0 years,respectively,P=0.497).The concurrent fibular fracture occurred in 53 cases and concurrent tibial shaft fracture in 3 cases.In axial CT view,metaphyseal fracture 5-10 mm proximal to the physis demonstrated as lateral-medial lines in most cases(69/96).The mean angle between the fracture line and the anterior distal tibia line was 11.7 degrees.There was no statistical significance between the angles in the two-part and three-part fractures(11.3degrees,15 degrees,respectively,P=0.288).All 96 cases demonstrated separation along the anterior portion of the epiphysis.Physeal fractures demonstrated five type fracture lines according to fracture line involving in the posterior epiphysis,and the anterior-to-posterior fracture coursing was the most frequent that resulted predominantly in two-part triplane fracture.The next most common was the "three-point" configuration which resulted in three-part fracture.In coronal CT view,the weight-bearing surface was violated in 41 cases and was not violated in 55.The anteromedial physis at Kump’s bump was fused in 79(82%)of the cases and was still open in 17(18%)in which the age difference was statistically significant(13.4years,12.7year,respectively,P=0.03).In 3D CT image,49 out of the 53 cases with concurrent fibular fracture were located in the distal metaphysis with oblique fracture line and being plantar flexion.ORIF was required in 93 patients in all whom the periosteum was entrapped at the anterolateral corner of the distal tibia.The fixation in metaphyseal fragment was performed in 88 and the transphyseal fixation was underwent in 19.The associated fibular fracture was fixed by screws or plates in 13.The mean follow-up was 7.2 months.The fractures were healed and ankle function was satisfactory in all patients.There was superficial infection in four cases and obvious scar in 18.Conclusions:The intramalleolar type and two-part type triplane fracture were the most common.The metapyseal and epiphyseal fragment can be approximately fixed by determining the fracture line configuration in axial CT scans.Further,the morphology of fibular fracture was demonstrated in 3D CT and the plantar force may be an important mechanism of injury in addition to the external rotation force for triplane fracture.The fixation of metaphyseal fragment alone may be enough to maintain the reduction in two-part and three-part triplane fracture.