Marcin Ceynowa1, Krzysztof Zerdzicki2, Pawel Klosowski3, Rafał Pankowski4, Marek Rocławski4, Tomasz Mazurek4. 1. Department of Orthopedic Surgery, Medical University of Gdańsk, ul. Nowe Ogrody 1-6, 80-803 Gdańsk, Poland. Electronic address: mceynowa@gumed.edu.pl. 2. Faculty of Civil and Environmental Engineering, Gdansk University of Technology, Gabriela Narutowicza 11/12, 80-233 Gdańsk, Poland. Electronic address: krzysztof.zerdzicki@pg.edu.pl. 3. Faculty of Civil and Environmental Engineering, Gdansk University of Technology, Gabriela Narutowicza 11/12, 80-233 Gdańsk, Poland. Electronic address: klosow@pg.edu.pl. 4. Department of Orthopedic Surgery, Medical University of Gdańsk, ul. Nowe Ogrody 1-6, 80-803 Gdańsk, Poland.
Abstract
BACKGROUND: Intertrochanteric fractures may occur in a bone with a wide medullary canal that may lead to significant mobility of a intramedullary nail, contrary to an extramedullary device. This study evaluates the Dynamic Hip Screw and the gamma nail in AO 31.A2.1 fractures in these circumstances. METHODS: Synthetic femora with canals drilled to 18 mm were used. Five fixation types were examined: a 2 - hole and a 4 - hole Dynamic Hip Screw with a 2 - hole plate, a standard gamma nail with dynamic and static distal locking and a long gamma nail. The specimens were tested with cyclic axial loading, from 500 N increasing of 50 N increments in each cycle. Force at failure, overall stiffness, stiffness at the fracture site, location and mode of failure were recorded. FINDINGS: The short gamma nails dislocated into varus under preload because the nail migrated laterally. The Dynamic Hip Screw was initially stable, but some specimens rotated around the lag screw. The gamma nail was rotationally stable. Both implants failed through femur fracture. The long gamma nailed failed by screw cut - out at forces lower than the ultimate force of the short gamma nail. INTERPRETATION: This study shows that the gamma nail is unstable in a large medullary canal but offers better rotational stability of the proximal fragment. A modification of the nail design or the operative technique may be considered.
BACKGROUND: Intertrochanteric fractures may occur in a bone with a wide medullary canal that may lead to significant mobility of a intramedullary nail, contrary to an extramedullary device. This study evaluates the Dynamic Hip Screw and the gamma nail in AO 31.A2.1 fractures in these circumstances. METHODS: Synthetic femora with canals drilled to 18 mm were used. Five fixation types were examined: a 2 - hole and a 4 - hole Dynamic Hip Screw with a 2 - hole plate, a standard gamma nail with dynamic and static distal locking and a long gamma nail. The specimens were tested with cyclic axial loading, from 500 N increasing of 50 N increments in each cycle. Force at failure, overall stiffness, stiffness at the fracture site, location and mode of failure were recorded. FINDINGS: The short gamma nails dislocated into varus under preload because the nail migrated laterally. The Dynamic Hip Screw was initially stable, but some specimens rotated around the lag screw. The gamma nail was rotationally stable. Both implants failed through femur fracture. The long gamma nailed failed by screw cut - out at forces lower than the ultimate force of the short gamma nail. INTERPRETATION: This study shows that the gamma nail is unstable in a large medullary canal but offers better rotational stability of the proximal fragment. A modification of the nail design or the operative technique may be considered.
Authors: Marcin Ceynowa; Krzysztof Zerdzicki; Pawel Klosowski; Maciej Zrodowski; Rafal Pankowski; Marek Roclawski; Tomasz Mazurek Journal: PLoS One Date: 2021-02-11 Impact factor: 3.240
Authors: Marcin Ceynowa; Krzysztof Zerdzicki; Pawel Klosowski; Rafal Pankowski; Marek Roclawski; Tomasz Mazurek Journal: PLoS One Date: 2020-10-29 Impact factor: 3.240