Comparing Locking Screw Direction Among Three Locking Plates for Lateral Clavicle Fractures: A Simulation Study

Abstract

BackgroundThe current study aimed to measure screw angles of three locking plates for lateral clavicle fractures and to assess the numbers of screws that could be inserted per fragment size to elucidate the size limitation that could be fixed by locking plates.MethodsThe authors assessed three locking plates for lateral clavicle fractures: distal clavicle plate [Acumed, LLC, Oregon, the USA], LCP clavicle plate lateral extension [Depuy Synthes, LLC, MA, the USA], and HAI clavicle plate [HOMS Engineering, Inc., Nagano, Japan]. Using three-dimensional plate models, the angles between the most medial and lateral locking screws on the coronal plane and between the most anterior and posterior locking screws on the sagittal plane were measured. Two examiners independently performed computer simulation to position the plates as laterally as possible in the ten normal three-dimensional clavicle models. A lateral fragment size of 10, 15, 20, 25, and 30 mm was simulated in the acromioclavicular joint and the number of screws completely inserted in each size of the fragment in the simulation was assessed. Subsequently, the area covered by locking screws on the inferior surface of the clavicle was measured.ResultsThe distal clavicle plate had relatively large screw angles (20° on the coronal plane and 32° on the sagittal plane), and the LCP clavicle lateral extension had a large angle (38°) on the sagittal plane. However, the angle of the HAI clavicle plate was at maximum 13° on the coronal or sagittal plane. The distal clavicle plate indicated the largest numbers of screws that could be inserted in each size of the bone fragment. For all locking plates, all screws could be inserted within 25 mm fragments. Among all locking plates, the distal clavicle plate could cover the largest area on the inferior surface of the clavicle by the screws.ConclusionsScrew angles and the numbers of screws that could be inserted in the lateral fragment differed among products. Other augmented fixation procedures should be considered for fractures with fragment sizes <25 mm that could not be fixed with sufficient number of screws.