Affiliations: [a] Unfallchirurgische Klinik, Medizinische Hochschule Hannover, Germany | [b] Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY, USA
Correspondence:
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Address for correspondence: Dr. med. Ralph Gaulke, Oberarzt, Unfallchirurgische Klinik der MHH, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany. Fax: +49 5032 963041; E-mail: gaulke.ralph@mh-hannover.de.
Abstract: The purpose of this prospective randomized comparative biomechanical study on six pairs of human cadaveric forearms was to study the mechanism of implant loosening and loss of lunate positioning and to discern whether primary stability following staple arthrodesis differs from plate fixation. Six wrists were randomly assigned to either group such that one wrist of each pair was fixed via titanium staples and the other via a mini-titanium plate with oblique screw. Under fluoroscopic guidance, passive extension and flexion of each wrist was performed using a spring balance. Traction force increased by 5 N at each step, ranging from 0 N to a maximum of 100 N. Fixation using a plate and oblique screw demonstrated greater flexibility than staple fixation. Loosening of the implant and/or the lunate occurred earlier following staple fixation in all pairs. Osteolytic rims around the staple limbs within the lunate occurred in all wrists. These were observed to be an early sign of implant loosening and fusion failure. The current investigators conclude that radiolunate fusion via miniplate and oblique screw is superior to staple fixation in terms of primary stability which is consistent with the radiological results of comparable clinical trails.
Keywords: Radiolunate arthrodesis, wrist biomechanics, implant loosening, cadaveric study
