The "Standing Peanut" Scaphoid View: A Semi-supinated Radiographic View for Intraoperative Evaluation of Screw Placement in Scaphoid Waist Fractures.

Scaphoid waist fractures are the most common fracture of the scaphoid. Operative management is indicated with unstable fractures and often for nondisplaced waist fractures to decrease time to union and return to work/sport. Screw placement within the central axis of the scaphoid is paramount and correlates with outcomes. Assessment of intrascaphoid screw placement is classically done via intraoperative fluoroscopy. An additional fluoroscopic view is presented to assist in confirming implant positioning. Along with the standard anterioposterior, lateral, pronated oblique, and "scaphoid" view we obtain a "standing peanut" view for assessment of central screw placement. This view also allows for further evaluation of center/center positioning and better assessment of fixation crossing the fracture into the proximal pole. The "standing peanut" view is best obtained in a sequential manner beginning with the forearm in neutral rotation. First, the forearm is then supinated 30 degrees; next, the wrist is placed at 45 degrees of ulnar deviation. Then finally, 10 degrees of wrist extension. We utilize this additional intraoperative view in conjunction with the standard fluoroscopic views for assessing and ensuring center-center implant positioning, particularly within the proximal pole. When ensuring center-center positioning, we prefer this view as an adjunct view to the standard fluoroscopic views intraoperatively. It provides a beneficial view of the proximal pole delineating the number of screw threads that have obtained proximal pole purchase. We have found it particularly useful in the setting of scaphoid waist fracture nonunion with the classic 'humpback' deformity after correction with volar interposition grafting. Standard radiographic views may be misinterpreted regarding implant positioning if there remains any residual flexion. The view requires little in the way of training to obtain once appreciated and exposes the patient to minimal additional radiation.

Intramedullary Threaded Nail Fixation Versus Plate and Screw Construct in Metacarpal Neck Fractures: A Biomechanical Study.

BACKGROUND: Indicated surgical management of metacarpal neck fractures varies with techniques, including Kirschner wire fixation, plate fixation, intramedullary fixation, and headless compression screw fixation, without demonstrated superiority. This study compares intramedullary threaded nail (ITN) fixation with a locking plate construct. METHODS: Index through small finger metacarpals were harvested from 10 embalmed cadavers. After application of appropriate exclusion criteria, remaining metacarpals underwent neck fracture creation by a three-point load to failure. Eight samples were randomly allocated to fixation with ITN fixation, and six were stabilized with a 2.3-mm seven-hole locking plate. Samples were then subjected to a second round of biomechanical testing using the same apparatus. Ultimate load between the intact tissue and the subsequently stabilized fracture was analyzed with a paired Student t -test. Percentage change in ultimate load in the intact tissue and stabilized tissue was calculated, and the magnitude of relative difference between the two groups was analyzed using unpaired Student t -tests. Statistical difference was defined by a P value of < 0.05. RESULTS: Both groups demonstrated the ability to handle a biomechanical load; however, both were significantly weaker than the intact tissue (paired Student t -test p ITN-fixed versus p ITN-intact = 0.006; p plate-fixed versus p plate-intact = 0.002). ITN samples demonstrated a higher load to failure (unpaired Student t -test p ITN-fixed versus p plate-fixed = 0.039). CONCLUSION: ITN provides a biomechanically stronger fixation constructed for vertically oriented metacarpal neck fractures compared with locking plate fixation. Both ITN and locking plate constructs provide stabilization capable of tolerating a biomechanical load; however, both fixation modalities are weaker than the native tissue.