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Journal of Bone and Joint Surgery - British Volume, Vol 88-B, Issue 9,
1257-1263.
doi: 10.1302/0301-620X.88B9.17822 Copyright © 2006 by British Editorial Society of Bone and Joint Surgery Polyaxially-locked plate screws increase stability of fracture fixation in an experimental model of calcaneal fractureM. Richter, MD, PhD, Trauma, General and Orthopaedic Surgeon, Head of Department1; P. Droste, BSc, Research Assistant2; T. Goesling, MD, Trauma Surgeon2; S. Zech, MD, Trauma Surgeon1; and C. Krettek, MD, FRACS, Trauma, General and Orthopaedic Surgeon, Head of Department, Professor
1 Department for Trauma, Orthopaedic and Foot Surgery, Coburg Medical Centre, Ketschendorferstrasse 33, 96450, Coburg, Germany. Correspondence should be sent to Dr M. Richter; e-mail: info{at}foot-trauma.org
Different calcaneal plates with locked screws were compared in an experimental model of a calcaneal fracture. Four plate models were tested, three with uniaxially-locked screws (Synthes, Newdeal, Darco), and one with polyaxially-locked screws (90° ± 15°) (Rimbus). Synthetic calcanei were osteotomised to create a fracture model and then fixed with the plates and screws. Seven specimens for each plate model were subjected to cyclic loading (preload 20 N, 1000 cycles at 800 N, 0.75 mm/s), and load to failure (0.75 mm/s). During cyclic loading, the plate with polyaxially-locked screws (Rimbus) showed significantly lower displacement in the primary loading direction than the plates with uniaxially-locked screws (mean values of maximum displacement during cyclic loading: Rimbus, 3.13 mm (SD 0.68); Synthes, 3.46 mm (SD 1.25); Darco, 4.48 mm (SD 3.17); Newdeal, 5.02 mm (SD 3.79); one-way analysis of variance, p < 0.001). The increased stability of a plate with polyaxially-locked screws demonstrated during cyclic loading compared with plates with uniaxially-locked screws may be beneficial for clinical use.
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