3D mapping: has the mystery of proximal tibia fractures been solved?

PURPOSE: One of the major limitations of the 2D fracture evaluation (Schatzker classification) is its failure to adequately assess fracture lines in the frontal plane and fracture displacement in the antero-posterior direction. 3D fracture line mapping includes steric assessment which can aid decision making with regards to the surgical approach and fixation scheme. We hypothesized that there are consistent fracture patterns and zones of comminution for proximal tibial fractures. METHODS: Radiographic data of 228 proximal tibia fractures were retrospectively included in this study. Fracture lines and zones of comminution were graphically superimposed onto a 3D template of an intact tibia after virtual reduction and normalization to identify major patterns of fracture and comminution. RESULTS: Out of 206 male and 21 female patients, 89 had a fracture of the lateral condyle only (Schatzker I and II), 53 involved the medial plateau only (Schatzker IV) and 86 had a high-grade fracture involving both the condyles (Schatzker V and VI). 64.5% of the fracture lines involving the medial plateau alone were in the coronal plane, and this number was even lesser (44.2%) in medial plateau involvement of bicondylar fractures. In bicondylar fractures, lines were usually not seen to pass directly through the posteromedial region. CONCLUSIONS: Medial tibial plateau fractures have a mix of coronal or sagittal fracture alignment. A clearer understanding of the 3D orientations of fractures based on CT scans can aid in diagnosing the pattern of fracture and adequate positioning of plates can be done to eventually improve operative outcomes.

Effect of fracture orientation on detection accuracy of vertical root fractures in non-endodontically treated teeth using cone beam computed tomography.

OBJECTIVES: This study aimed to investigate the effect of fracture orientation on the detection accuracy of vertical root fractures (VRFs) in non-endodontically treated teeth using four different cone beam computed tomography (CBCT) units. MATERIALS AND METHODS: Thirty eight out of 148 extracted human permanent teeth were chosen randomly, and VRFs were artificially induced to result in 20 mesiodistally and 18 buccolingually oriented root fractures. The fracture width was subsequently measured. All the teeth were scanned with four CBCT units. CBCT images were evaluated independently by two observers. Area under the receiver operating characteristic curve (AUC), sensitivity, and specificity were calculated for each observer and fracture orientation. The AUC between the two fracture orientations was compared using Z test. RESULTS: The mean fracture width was 140 µm (standard deviation 26.8 µm). A statistically significant difference was found between the mesiodistal and buccolingual VRFs for the AUC from the CBCT unit 3D Accuitomo 170 (p = 0.02). There were no statistically significant differences between the mesiodistal and buccolingual VRFs for AUCs from the CBCT units NewTom VGi (p = 0.21), ProMax 3D Mid (p = 0.23), and i-CAT FLX (p = 0.21). CONCLUSION: Fracture orientations of teeth with VRFs in non-endodontically treated teeth may play a role in the detection accuracy of CBCT images, but this effect seems to be dependent on the CBCT unit used. CLINICAL RELEVANCE: Although for most of the CBCT units tested, the fracture orientation of VRF in non-endodontically treated teeth seems not to play a role for the diagnosis, clinical data is needed to further assess the impact of different devices on VRF detection.

Musculoskeletal modeling-based definition of load cases and worst-case fracture orientation for the design of clavicle fixation plates.

Mechanical performance of clavicle fracture fixation plates is often evaluated using finite element (FE) analysis. Typically, these studies use simplified loading conditions and assume a transversal fracture orientation. However, the loading conditions and fracture orientation influence how the fracture site and thus fixation plate is loaded. In this study, a musculoskeletal model that included the clavicle muscles and scapulohumeral rhythm was defined based on previously published models. The standard OpenSim workflow (inverse kinematics, inverse dynamics, static optimization, and joint reaction analysis) was used to calculate muscle and joint contact forces based on 3D marker data collected in three subjects during seven activities of daily living (ADL). These loading conditions were then applied to a 3D clavicle model with three different fracture orientations and the mean resulting moments on both fragments were calculated to assess fracture stability. Magnitude of glenohumeral contact forces showed good agreement with instrumented shoulder prosthesis data, whereas simulated muscle activations were comparable to experimental EMG data. An oblique fracture orienting from superomedial to inferolateral was the least self-stabilizing. The loading to which the clavicle is exposed during ADL tasks is more complex than the simplified loading conditions typically used as boundary conditions in FE analyses of clavicle fracture fixation plates. Additionally, transversal fractures did not represent the least self-stabilizing fracture orientation, and thus calculated stresses in the plate could be underestimated. Therefore, more complex loading conditions and evaluation of a midshaft fracture running from superomedial to inferolateral is more relevant in FE analyses of midshaft clavicle fracture fixation plates.

Is All Anterior Oblique Fracture Orientation Really a Contraindication to Anterior Screw Fixation of Type II and Rostral Shallow Type III Odontoid Fractures?

OBJECTIVE: It is debatable whether an anterior oblique fracture orientation is really a contraindication to anterior odontoid screw fixation. The purpose of this study was to investigate the feasibility of anterior odontoid screw fixation of type II and rostral shallow type III fracture with an anterior oblique fracture orientation. METHODS: The authors evaluated 16 patients with type II and rostral shallow type III odontoid fracture with an anterior oblique fracture orientation. Of these 16 patients, 8 (group 1) were treated by anterior odontoid screw fixation, and 8 (group 2) by a posterior C1-2 arthrodesis. RESULTS: Of the 8 patients in group 1, seven patients achieved solid bone fusion (87.5%), and one experienced screw back-out of the C-2 body two months after anterior screw fixation. All patients treated by posterior C1-C2 fusion in group 2 achieved successful bone fusion. Mean fracture displacements and fracture gaps were not significantly different in two groups. (p=0.075 and 0.782). However, mean fracture orientation angles were 15.3±3.2 degrees in group 1, and 28.6+8.1 degrees in group 2 (p=0.002), and mean fragment angulations were 3.2±2.1 degrees in group 1, and 14.8±6.7 degrees in group 2 (p=0.001). CONCLUSION: Even when the fracture lines of type II and rostral shallow type III fractures are oriented in an anterior oblique direction, anterior odontoid screw fixation can be feasible in carefully selected patients with a relatively small fracture orientation angle and relatively small fragment angulation.