| Part One Analysis of medial plateau fracture injury patterns using quantitative 3D measurementObjective: The purpose of the present study was to determine the injury patterns of medial tibial plateau fractures using 3D model simulation and quantitative 3D measurements.It can help surgeons to understand the process of medial plateau fracture and make the corresponding treatment plan.Methods: Seventy-eight consecutive AO/OTA type 41-B tibial plateau fractures were retrospectively analyzed using CT-based 3D models and quantitative 3D measurements.The knee posture at the moment of fracture occurrence was simulated,and various knee angles in the sagittal,coronal,and axial planes were measured to evaluate the mechanism of medial tibial plateau fracture.The mean valgus-varus,hyperextension-flexion,and internal-external rotation angles were determined,and the chis-quare test was used for comparisons of categorical varus and valgus force data to determine the main force direction in Wahlquist type C fractures.Results: Angle measurements in the coronal planes showed that 28(35.9%)medial tibial plateau fractures resulted from a varus injury pattern,while 50 fractures(64.1%)resulted from a valgus pattern.Valgus force produced significantly more Wahlquist type C fractures(37 of 50 fractures)than varus force(2 of 28 fractures)(p < 0.05).There was no significant difference in the cases of patients with type C fractures between the tibial internal and external rotation injury patterns(P > 0.05).Conclusions: Valgus force was the cause of 64.1% of the medial tibia plateau fractures in the present cohort.Furthermore,valgus force produced more Wahlquist type C fractures than varus force.The present findings will help orthopedists understand the injury mechanism of the Wahlquist classification system,and will facilitate the identification of the common features of medial tibial plateau fractures induced by specific injury patterns.Part Two Analysis of posterior bilateral condylar fracture displacement in Schatzker Ⅳ tibial plateau fractures(typical Moore typeⅠ)with quantitative 3D measurementsObjective: Tibial plateau fractures(TPFs)are a kind of serious intra-articular fractures which is difficult to treat.Tibial plateau fractures are commonly associated with ligament injury.Fracture-dislocation is always present in tibial plateau fractures which it obviously takes multiple stresses to cause.Moore type Ⅰ is the most common fracture-dislocation of tibial plateau fractures which is also the mainly involving medial plateau.The purpose of this study was to characterize injury mechanism of posterior bilateral condylar fracture in Schatzker Ⅳ(Moore I type tibial plateau fracture features),especially the tibial translation relative to femur.Methods: In total,54 cases of posterior bilateral condylar fracture in Schatzker Ⅳ were retrospectively reviewed.The injury pattern was simulated and analyzed by quantitative 3D measurements with Mimics and 3-Mathic software.According to the spatial position of femoral and tibial 3D models,the tibia axis,the femoral axis,the femoral posterior condylar line,femoral lateral condyle point and medial condyle point and three reference planes(sagittal plane,coronal plane and axial plane)were produced.The positions of knee were simulated at the moment of fractures occurrence.The marking lines and points of the knee models at the different moment were projected in the sagittal,coronal and axial reference plane.The markers projected in different planes were measured to analysis the angle and translation at the moment of fractures occurrence.The flexion and valgus angle of knee joint were compared in different injury patterns.The rotation angle of different injury patterns were compared with 7.8°.Results: The 43 fractures exhibited the flexion-valgus-internal rotation.The flexion-valgus-external rotation injury pattern was noted in 11 cases.All the fractures of posterior bilateral condylar fracture in Schatzker Ⅳ were the consequence of valgus force in the coronal plane.In flexion-valgus-internal rotation,the retrodisplacement of lateral tibial condyle relative to femur was22.10(11.09)mm and that of medial tibial condyle was 33.30(6.76)mm.The translation of lateral tibial condyle relative to femur was 13.12(4.4)mm and that of the medial condyle was 11.10(4.0)mm in the flexion-valgus-internal rotation.The angle of knee flexion was 130.00(12.89)in this injury pattern.In flexion-valgus-external rotation,the retrodisplacement of lateral tibial condyle relative to femur was 19.80(5.16)mm and that of medial tibial condyle was13.80(5.40)mm.The translation of lateral tibial condyle relative to femur was16.70(9.03)mm and that of the medial condyle was 11.05(9.60)mm in the flexion-valgus-external rotation.The angle of knee flexion was 122.70(10.64)in this injury pattern.The rotation angle was significant greater than 7.8°(P<0.05).The avulsion fracture of anterior cruciate ligament happened in all cases.Conclusions: In this study,the data showed that 2 different injury patterns of typical MooreⅠtype fractures with distinct,recurrent characteristics in 3D simulation technique.The morphological feature of hyperflexion injury pattern were also showed in the present study.The injury mechanism demonstrated the tibial plateau fracture-dislocation associated with the tibial and femoral relative translation,rotation and ligament injury.Part Three Analysis of characteristics and injury mechanism in Wahl-quist classification.Objective: At present,the Wahlquist classification is the most widely used subtype for medial plateau fractures.It is convenience to distinguish medial plateau fractures by the main fracture line on the anteroposterior X-ray of the injured limb.However,the morphological characteristics and injury mechanism of Wahlquist classification has not summarized in the previous studies.In this study,the morphological characteristics and injury mechanism of Wahlquist classification were analyzed by the axial view of the tibial plateau and the 3D fracture model with the imaging data.Methods: In total,112 cases of typical medial tibial plateau fractures were retrospectively reviewed.According to the Wahlquist classification,medial plateau fractures were divided into A,B and C groups.After classification,the axial morphological characteristics and injury mechanism in three types of Wahlquist classification was collected and summarized.Results: By the location of fracture line in the anteroposterior X-ray films,the patients were divided into three groups according to Wahlquist classification.The morphological characteristics of the tibial plateau in the axial view were recorded and analyzed.In this study,all anterior medial plateau fractures were the Wahlquist type A(12 cases).There were two fracture patterns in Wahlquist type B(22 cases).The first fracture pattern was the oblique medial condyle fracture.The second fracture pattern was the comminuted medial plateau fracture.The fracture patterns of Wahlquist type C were complicated with a total of 5 fracture patterns.In Wahlquist type C fractures,the lateral plateau was all involved,especially the articular surface of which collapsed in the majority of Wahlquist type C fractures(87.17%).In type C fractures,the posterior lateral plateau articular surface collapsed in 37 cases with a majority of medial plateau fractures.12 patients were presented with posterior lateral plateau articular surface depression with posterior medial plateau fracture.In 14 patients,the articular surface of the anterolateral plateau collapsed with the medial condyle fracture.10 patients were presented longitudinal fracture lines of the lateral plateau with medial condylar fractures.There were longitudinal articular collapse in lateral plateau and medial condylar fracture in 5 cases.Conclusion:This study demonstrated that the cases of type C were the most common in the Wahlquist classification.From type A to C,the injury mechanism and characteristics became more complicated.For the differences of morphological characteristics in each Wahlquist type,it is difficult to exclusively divived the injury mechanism of medial plateau fracture according to Wahlquist classification. |
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