title: [Internal fixation of radial shaft fractures: Anatomical and biomechanical principles].
abstract: Radius is a critical bone for functioning of the forearm and therefore its reconstruction following fracture of its shaft must be anatomical in all planes and along all axes. The method of choice is plate fixation. However, it is still associated with a number of unnecessary complications that were not resolved even by introduction of locking plates, but rather the opposite. All the more it is surprising that discussions about anatomical and biomechanical principles of plate fixation have been reduced to minimum or even neglected in the current literature. This applies primarily to the choice of the surgical approach, type of plate, site of its placement and contouring, its working length, number of screws and their distribution in the plate. At the same time it has to be taken into account that a plate used to fix radius is exposed to both bending and torsion stress. Based on our 30-year experience and analysis of literature we present our opinions on plate fixation of radial shaft fractures:We always prefer the volar Henry approach as it allows expose almost the whole of radius, with a minimal risk of injury to the deep branch of the radial nerve.The available studies have not so far found any substantial advantage of LCP plates as compared to 3.5mm DCP or 3.5mm LC DCP plates, quite the contrary. The reason is high rigidity of the locking plates, a determined trajectory of locking screws which is often unsuitable, mainly in plates placed on the anterior surface of the shaft, and failure to respect the physiological curvature of the radius. Therefore based on our experience we prefer "classical" 3.5mm DCP plates.Volar placement of the plate, LCP in particular, is associated with a number of problems. The volar surface covered almost entirely by muscles, must be fully exposed which negatively affects blood supply to the bone. A straight plate, if longer, either lies with its central part partially off the bone and overlaps the interosseous border, or its ends overhang the bone laterally. In a locking plate with a fixed determined trajectory of screws, the locking screws in the central holes of the plate pass off the shaft centre only through a thin interosseous border (medial position), or screws at the ends of the plate are inserted eccentrically (lateral position). Both these techniques reduce stability of internal fixation. Where the plate overlaps the interosseous border, it is difficult to control the mutual rotation of the two main fragments. A shorter LCP plate increases rigidity of fixation, suppresses bone healing and often leads to non-union.Placement of the plate on the lateral surface of the radius is more beneficial from the viewpoint of the bending and torsion stress. Lateral surface of the radius is a tension site, its distal half is not covered by muscles which eliminates the necessity to release them, the interosseous border is not obscured by plate and all this allows a safe control of rotational position of fragments. A properly pre-bent plate follows the physiological curvature of the lateral surface of the radius. Full tightening of standard screws will fix both main fragments firmly to the apex of plate concavity and increase stability of the internal fixation. Due to the shape of the cross-section of the radial shaft, the trajectory of screws is the longest in case of lateral placement of the plate, which increases rotational stability.We place the plate always in a minimal three-hole length on each main fragment. Transverse two-fragment fractures may be fixed with a 2+2 configuration, i.e. with two screws on each main fragment. Fractures with an inter-fragment or comminuted zone are fixed in the 3+3 mode. More extensive comminutions, defects or segmental fractures require 4 plate holes on each fragment, but not more. When drilling screw holes the drill must be directed into the interosseous border. As a result, the screw has the longest trajectory and the best fixation in the bone. Perforation of the anterior or posterior surface of the radius considerably shortens the trajectory of the screw and thus reduces stability of internal fixation.
authors.forename: J
authors.initials: J
authors.lastname: Bartoníček
authors.forename: O
authors.initials: O
authors.lastname: Naňka
authors.forename: M
authors.initials: M
authors.lastname: Tuček
mesh_terms: D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D018460:Fractures, Comminuted / Q000601:surgery; D006801:Humans; D008297:Male; D011884:Radius / Q000033:anatomy & histology / Q000601:surgery; D011885:Radius Fractures / Q000601:surgery*