Objective:To analyze the correlation between the posterior malleolus fracture and fixation and the rotational stability of the ankle and to explore the surgical indications for posterior malleolus fracture aiming to provide the theories for the diagnosis and treatment of disorder.Methods:Twenty fresh frozen cadaver specimens were selected. Further, the extent of the tibial insertion of the posterior inferior tibiofibular ligament (PITFL) and inferior transverse tibiofibular ligament (ITTFL) complex was dissected and measured. Based on the tibial insertion of the ligament complex, the model for the supination-external rotation degree 3 ankle fracture with a posterior malleolar fragment and syndesmosis diastasis was created. Moreover, the area threshold of the posterior tibial insertion of posterior malleolus fracture was biomechanically assessed. The difference of the antirotating ability of the ankle-stiffness between simple posterior malleolus fixation and simple syndesmotic fixation was analyzed statistically.Results:The PITFL and ITTFL were presented in all specimens with relatively broad in PITFL tibial insertion. The PITFL was attached to the posterolateral tibia. The distance between the highest point of the tibial insertion and the articular line was 45.2±5.6 mm, while the ITTFL was attached to the posterior distal tibia. The distance between the highest point of the tibial insertion and the articular line was 5.5±1.0 mm. The width of the tibial insertion of the PITFL and ITTFL complex decreased as the distance from the joint line increased. Biomechanical analysis showed that the threshold of posterior area of posterior malleolus fracture was 1/4S. The stiffnesses of posterior malleolus fixation and syndesmosis stabilization were 0.264±0.080 N·m/° and 0.164 ± 0.061 N·m/°, respectively. The percentage of stiffness restored by posterior ankle fixation was 60.9%±10.2%, which was greater than that by syndesmosis stabilization 37.5%±7.9% ( t=17.09, P<0.001) . Conclusion:The surgical technique for posterior malleolus fracture should consider restoration of the axial and rotational stability of the ankle simultaneously. Posterior malleolus fracture fixation is recommended when the syndesmosis is unstable with the area ratio of posterior tibial insertion of posterior malleolus fracture greater than or equal to 1/4. Syndesmotic fixation is proposed to restore and maintain the rotational stability of the ankle when the syndesmosis is unstable with the area ratio less than 1/4. Regardless of the area ratio, the surgical indications for stable syndesmosis depend on the impact of the posterior malleolus fracture on the axial stability of tibiotalar joint, on the involved articular surface area and on the displacement degree of posterior malleolus fragment.

Objective:To compare the efficacy of staged versus elective operation for treating acute closed fracture-dislocation of tarsometatarsal joint complex.Methods:A retrospective cohort study was used to analyze the clinical data of 26 patients with acute closed fracture-dislocation of tarsometatarsal joint complex admitted to Tongji Hospital of Tongji University from January 2017 to January 2021, of whom 18 were males and 8 were females, aged 32-52 years [(44.3±5.2)years]. According to the time from injury to admission, 14 patients admitted within 8 hours after injury underwent staged surgical treatment (staged group), and 12 patients admitted more than 8 hours after injury underwent elective surgery (elective group). In the staged group, emergency reduction and temporary internal fixation with K-wire were done under the supervision of a C-arm X-ray machine in the first stage, while after the swelling subsided, open reduction and internal fixation were done for tarsometatarsal joint fracture-dislocation in the second stage. In the elective group, open reduction and internal fixation were performed for tarsometatarsal joint fracture-dislocation on a scheduled basis after the swelling subsided. The operation time, hospitalization time and fracture healing time were recorded. The visual analogue score (VAS) and American Orthopedic Foot and Ankle Society (AOFAS) midfoot score were evaluated before operation, at 1, 6, 12 months after operation and at the final follow-up. The rate of complications was observed after operation.Results:All patients were followed up for 12-24 months [(18.5±3.8)months]. The operation time, hospitalization time and fracture healing time in the staged group were (77.3±5.6)minutes, (14.3±2.2)days and (12.3±1.2)weeks, respectively, significantly shorter than those in the elective group [(101.5±7.5)minutes, (20.3±5.2)days and (14.3±2.2)weeks] (all P<0.01). VAS significantly decreased and AOFAS midfoot score significantly increased in both groups as postoperative time increased (all P<0.05). There were no significant differences in VAS between the two groups before operation, at 12 months after operation or at the final follow-up (all P>0.05). The VAS at 1, 6 months after operation was (4.4±0.8)points and (2.1±0.4)points in the staged group, significantly lower than those in the elective group [(6.0±1.0)points and (3.5±0.6)points] (all P<0.01). There was no significant difference in preoperative AOFAS midfoot score between the two groups ( P>0.05). The AOFAS midfoot score at 1, 6, 12 months after operation and at the final follow-up was (67.6±4.5)points, (75.7±5.2)points, (83.6±2.2)points and (85.9±4.3)points in the staged group, significantly higher than those in the elective group [(60.2±3.9)points, (70.2±3.4)points, (75.4±3.3)points and (78.7±4.4)points] (all P<0.01). The rate of complications was 14.3% (2/14) in the staged group, significantly lower than that in the elective group [33.3% (4/12)] ( P<0.05). Conclusion:Compared to traditional elective surgery, staged surgery for acute closed fracture-dislocation of tarsometatarsal joint complex has the advantages of shortened operation time, hospitalization time and fracture healing time, eary pain relief, improved functional recovery of the foot and reduced postoperative complications.

Objective:To propose a new classification of posterior malleolus fracture to further clarify its pathoanatomy.Methods:Twenty fresh frozen cadaver specimens of normal morphology of lower limbs were selected and dissected and the extent of the tibial insertion of posterior malleolus associated ligaments was measured. At the same time, a retrospective case series analysis was made on the clinical and CT information of 296 patients with posterior malleolus fracture treated at Tongji Hospital of Tongji University from January 2012 to July 2020 or at Karamay Central Hospital from January 2018 to July 2020. The percentage of articular involvement of the fracture, proximal displacement of the posterior malleolus fracture and extent of posterior talar subluxation were measured. A clinically practical new classification system for posterior malleolus fracture was created by correlating posterior malleolus associated ligaments with CT images of posterior malleolus fracture. The new classification included three types: type I was posterior malleolus fracture with only the tibial insertion of inferior transverse tibiofibular ligament involved; type II was posterior malleolus fracture with both the tibial insertions of inferior transverse tibiofibular ligament and posterior inferior tibiofibular ligament involved, which was divided into subtypes IIA and IIB based on the presence of articular cartilage and subchondral bone damage, compression or Die-Punch fragments; type III was posterior malleolus fracture that involved all the tibial insertions of inferior transverse tibiofibular ligament, posterior inferior tibiofibular ligament and posterior tibiotalar ligament, which was sub-classified into subtypes III A and III B according to number of fracture fragments. Anatomic characteristics of the extent of the tibial insertion of posterior malleolus associated ligament, CT imaging parameters for posterior malleolus fracture and corresponding fracture typing were determined. In addition, the new classification system for posterior malleolus fracture was compared with Haraguci classification and Mason classification.Results:Posterior malleolus associated ligaments included the posterior inferior tibiofibular ligament, inferior transverse tibiofibular ligament and posterior tibiotalar ligament from posterolateral to posteromedial tibia. The posterior inferior tibiofibular ligament was attached to the posterolateral tibia and the distance between the highest point of its tibial insertion and the joint line was (45.2±5.6)mm. The inferior transverse tibiofibular ligament was attached to the posterior distal tibia and the distance between the highest point of its tibial insertion and the joint line was (5.5±1.0)mm. The posterior tibiotalar ligament was attached to the posterior colliculus and intercollicular groove of the medial malleolus and the distance between the center of its tibial insertion and the intercollicular groove was (2.5±0.6)mm. Among 296 patients with posterior malleolus fracture, there were 36 patients with type I, 229 with type II (150 type IIA, 79 type IIB) and 31 with type III (11 type IIIA, 20 type IIIB). The percentage of articular involvement of the fracture, proximal displacement of posterior malleolus fracture and extent of posterior talar subluxation in type IIB fracture were significantly greater than those in type II A fracture [23.7(18.6, 28.8)% vs. 18.4(12.7, 21.7)%, 4.1(2.1, 6.0)mm vs. 1.9(0.2, 3.0)mm, 4.7(1.5, 6.2)mm vs. 2.3(1.1, 3.0)mm] (all P<0.01). The proximal displacement of posterior malleolus fracture and extent of posterior talar subluxation in type III fracture were significantly greater than those in type II fracture [7.2(6.0, 8.2)mm vs. 2.7(0.4, 4.0)mm, 10.1(6.0, 15.0)mm vs. 3.1(1.1, 5.0)mm] (all P<0.01). The new classification for posterior malleolus fracture combined the posterior malleolus ligament and injury mechanism of posterior malleolus fracture as compared with Haraguchi classification, which not only further detailed the classification, but also was more practical in clinic for increased the severity of injury was elevated with higher classification level. The new classification was more comprehensive as compared with Mason classification for it mainly added the type of simple-rotation-type posterior malleolus fracture (type IIA of the new classification). Conclusions:In combination with posterior malleolus associated ligaments, injury mechanism and fracture morphology, posterior malleolus fracture is divided into three types. The new classification system more comprehensively describes pathoanatomy of posterior malleolus fracture that contributes to related basic research and clinical diagnosis and treatment.

OBJECTIVE: To establish the finite element model of varus-type ankle arthritis and to implement the finite element mechanical analysis of different correction models for tibial anterior surface angle (TAS) in supramalleolar osteotomy. METHODS: A female patient with left varus-type ankle arthritis (Takakura stage Ⅱ, TAS 78°) was taken as the study object. Based on the CT data, the three-dimensional model of varus-type ankle arthritis (TAS 78°) and different TAS correction models [normal (TAS 89°), 5° valgus (TAS 94°), and 10° valgus (TAS 99°)] were created by software Mimics 21.0, Geomagic Wrap 2021, Solidworks 2017, and Workbench 17.0. The 290 N vertical downward force was applied to the upper surface of the tibia and 60 N vertical downward force to the upper surface of the fibula. Von Mises stress distribution and stress peak were calculated. RESULTS: The finite element model of normal TAS was basically consistent with biomechanics of the foot. According to biomechanical analysis, the maximum stress of the varus model appeared in the medial tibiotalar joint surface and the medial part of the top tibiotalar joint surface. The stress distribution of talofibular joint surface and the lateral part of the top tibiotalar joint surface were uniform. In the normal model, the stress distributions of the talofibular joint surface and the tibiotalar joint surface were uniform, and no obvious stress concentration was observed. The maximum stress in the 5° valgus model appeared at the posterior part of the talofibular joint surface and the lateral part of the top tibiotalar joint surface. The stress distribution of medial tibiotalar joint surface was uniform. The maximum stress of the 10° valgus model appeared at the posterior part of the talofibular joint surface and the lateral part of the top tibiotalar joint surface. The stress on the medial tibiotalar joint surface increased. CONCLUSION With the increase of valgus, the stress of ankle joint gradually shift outwards, and the stress concentration tends to appear. There was no obvious obstruction of fibula with 10° TAS correction. However, when TAS correction exceeds 10° and continues to increase, the obstruction effect of fibula becomes increasingly significant.
Humans ; Female ; Tibia/surgery* ; Finite Element Analysis ; Ankle ; Arthritis ; Fibula/surgery* ; Ankle Joint/surgery*