Biomechanical Evaluation of the Fixation Methods for Transcondylar Fracture of the Humerus:ONI Plate Versus Conventional Plates and Screws

We biomechanically evaluated the bone fixation rigidity of an ONI plate (Group I) during fixation of experimentally created transcondylar humerus fractures in cadaveric elbows, which are the most frequently observed humeral fractures in the elderly, and compared it with the rigidity achieved by 3 conventional fixation methods:an LCP reconstruction plate 3.5 using a locking mechanism (Group II), a conventional reconstruction plate 3.5 (CRP) with a cannulated cancellous screw (Group III), and a CRP with 2 cannulated cancellous screws (CS) in a crisscross orientation (Group IV). In the axial loading test, the mean failure loads were:Group I, 98.9+/-32.6;Group II, 108.5+/-27.2;Group III, 50.0+/-7.5;and Group IV, 34.5+/-12.2 (N). Group I fixations failed at a significantly higher load than those of Groups III and IV (p0.05). In the extension loading test, the mean failure loads were:Group I, 34.0+/-12.4;Group II, 51.0+/-14.8;Group III, 19.3+/-6.0;and Group IV, 14.7+/-3.1 (N). Group IV fixations showed a significantly lower failure load than those of Group I (p0.05). The fixation rigidities against mechanical loading by the ONI plate and LCP plate were comparable. These results suggested that an ONI system might be superior to the CRP and CS method, and comparable to the LCP method in terms of fixation rigidity for distal humerus fractures.</p

Fracture Line Distributions of Undisplaced Distal Radius Fractures in Relation to Rupture of the Extensor Pollicis Longus Tendon

Rupture of the extensor pollicis longus (EPL) tendon is a known complication after undisplaced distal radius fracture (DRF). However, no report has revealed the relationship between EPL tendon rupture and the fracture pattern. Thus, this study aimed to investigate the characteristics of fractures at risk of EPL tendon rupture using fracture line mapping of undisplaced DRFs. This study used computed tomography imaging data of undisplaced DRFs with (n=18) and without EPL tendon rupture (n=52). Fracture lines obtained from 3D reconstruction data were drawn manually after matching with a 2D template wrist model. Fracture maps represented the fracture line distribution by superimposing the fracture lines of all 70 patients. Heat maps showed the relative frequency of the fracture lines as a gradual color change. Fracture lines of cases with EPL tendon rupture were concentrated in the proximal border of Lister’s tubercle. By contrast, fracture lines of cases without EPL tendon rupture were relatively dispersed