Mechanical Properties of F Plate in Intraarticular Calcaneal Fractures

PURPOSE: We evaluated the mechanical properties of F plate fixation comparing with Y plate and a screw fixation for the intraarticular calcaneal fractures using synthetic bones. MATERIALS AND METHODS: Using 12 synthetic calcaneal bones, newly designed F plate was compared with the Y-plate, most commonly used, regarding the change of Bohler angle and the displacement of the thalamic fragments of the calcaneus after axial compressive loading by Instron 6022. RESULTS: Y plate fixation lost 8degrees of Bohler angle in average after axial compressive load and 2.6degrees in F plate fixation. Thalamic fragments were displaced 1.72 mm in average in Y plate fixation group and 0.73 mm in F plate fixation group. CONCLUSION: F plate offered more firm fixation than Y plate in the intraarticular calcaneal fracture in the aspect of maintaining the Bohler angle and preventing displacement of the thalamic fragments of calcaneus against axial compressive loading.

Refractures of Upper Extremity in Children

PURPOSE: To investigate the etiologic factors related to refractures of the upper extremity in children MATERIALS AND METHODS: 18 refractures of the upper extremity were divided into three groups according to the location of initial fractures: Supracondyle fractures of the humerus, lateral condyle fracture of the humerus, and the forearm bone fractures. They were analyzed in terms of the type of refractures (early refracture occurring at the immature callus and late refracture occurring at the remodeled bone), fracture patterns, and the existence of underlying deformity. RESULTS: Nine supracondyle fractures had refractures at the supracondyle (2 cases) and the lateral condyle (7 cases), in which underlying cubitus varus were present in 6 cases. Three lateral condyle fractures had refractures at the supracondyle (1 case) and the lateral condyle (2 cases), in which one case had underlying cubitus varus. All but one case in the group of humerus fractures were late refractures and treated operatively except one. Of 6 refractures of forearm, 5 were early refractures and occurred within 9 weeks at the original site: 4 at the diaphysis of both bones of forearm and 1 at the diaphysis of ulna. All cases in the group of forearm fractures had volar angulation before the refracture, and treated conservatively except one CONCLUSION: In the humerus, underlying cubitus varus was the most important predisposing factor to refractures and the lateral condyle fractures were common. In the forearm, volar angulation of the diaphysis were related to refractures, and complete and circular consolidation of the primary fracture of forearm was thought to be important to prevent refracture.

Correlation between Anterior and Posterior Obliquity of the Sliding Lag Screw and Stability in Unstable Intertrochanteric Fractures

PURPOSE: To investigate the characteristics of the sliding pattern of the proximal fragment (head and neck) in unstable intertrochanteric fractures, which were fixed with a dynamic hip screw (DHS) with anterior to posterior or posterior to anterior insertion angle in the axial view. MATERIALS AND METHODS: AO type A2.1 intertrochanteric fracture was reproduced in 10 proximal femur model (Synbone, Malans, Switzerland). Five fractured models were reduced and fixed using DHS with anterior to posterior insertion angle (group 1) and five models were fixed with posterior to anterior angle (group 2). Load of 500 N (30 cycles) was applied to the fracture fragment-plate complex using Instron 6022. Data on the distance of sliding and the angle of rotation of the proximal fragment were collected and analyzed. RESULTS: No significant difference was noted statistically in the distance of sliding between the two groups (p=0.92). However, the mean angle of rotation was 13.4degrees and 8.0degrees in group 1 and 2, respectively and the difference was statistically significant (p=0.012). Anterior cortical fracture of distal fragment was noted in 3 cases of group 1. There was no fracture of the anterior cortex in group 2. CONCLUSION: In unstable intertrochanteric fracture, the insertion angle of the lag screw in axial view does seem to play a role in the fate of bone-plate complex. Early eccentric contact of both fragments caused rotation of the proximal fragment in all cases and anterior cortical fracture of the distal fragment in 3 cases of group 1.