Mehran Moazen1, Andreas Leonidou2, Joseph Pagkalos2, Arsalan Marghoub1, Michael J Fagan3, Eleftherios Tsiridis4. 1. Department of Mechanical Engineering, University College London, London, UK. 2. Academic Orthopaedics and Trauma Unit, Aristotle University Medical School, Thessaloniki, Greece. 3. Medical and Biological Engineering, School of Engineering, University of Hull, Hull, UK. 4. Academic Orthopaedics and Trauma Unit, Aristotle University Medical School, Thessaloniki, Greece; Academic Department of Orthopaedic and Trauma, University of Leeds, Leeds, UK; Division of Surgery, Department of Surgery and Cancer, Imperial College London, London, UK.
Abstract
BACKGROUND: Lack of fracture movement could be a potential cause of periprosthetic femoral fracture (PFF) fixation failures. This study aimed to test whether the use of distal far cortical locking screws reduces the overall stiffness of PFF fixations and allows an increase in fracture movement compared to standard locking screws while retaining the overall strength of the PFF fixations. METHODS: Twelve laboratory models of Vancouver type B1 PFFs were developed. In all specimens, the proximal screw fixations were similar, whereas in 6 specimens, distal locking screws were used, and in the other six specimens, far cortical locking screws. The overall stiffness, fracture movement, and pattern of strain distribution on the plate were measured in stable and unstable fractures under anatomic 1-legged stance. Specimens with unstable fracture were loaded to failure. RESULTS: No statistical difference was found between the stiffness and fracture movement of the two groups in stable fractures. In the unstable fractures, the overall stiffness and fracture movement of the locking group was significantly higher and lower than the far cortical group, respectively. Maximum principal strain on the plate was consistently lower in the far cortical group, and there was no significant difference between the failure loads of the 2 groups. CONCLUSION: The results indicate that far cortical locking screws can reduce the overall effective stiffness of the locking plates and increase the fracture movement while maintaining the overall strength of the PFF fixation construct. However, in unstable fractures, alternative fixation methods, for example, long stem revision might be a better option.
BACKGROUND: Lack of fracture movement could be a potential cause of periprosthetic femoral fracture (PFF) fixation failures. This study aimed to test whether the use of distal far cortical locking screws reduces the overall stiffness of PFF fixations and allows an increase in fracture movement compared to standard locking screws while retaining the overall strength of the PFF fixations. METHODS: Twelve laboratory models of Vancouver type B1 PFFs were developed. In all specimens, the proximal screw fixations were similar, whereas in 6 specimens, distal locking screws were used, and in the other six specimens, far cortical locking screws. The overall stiffness, fracture movement, and pattern of strain distribution on the plate were measured in stable and unstable fractures under anatomic 1-legged stance. Specimens with unstable fracture were loaded to failure. RESULTS: No statistical difference was found between the stiffness and fracture movement of the two groups in stable fractures. In the unstable fractures, the overall stiffness and fracture movement of the locking group was significantly higher and lower than the far cortical group, respectively. Maximum principal strain on the plate was consistently lower in the far cortical group, and there was no significant difference between the failure loads of the 2 groups. CONCLUSION: The results indicate that far cortical locking screws can reduce the overall effective stiffness of the locking plates and increase the fracture movement while maintaining the overall strength of the PFF fixation construct. However, in unstable fractures, alternative fixation methods, for example, long stem revision might be a better option.
Authors: Jason Coquim; Joseph Clemenzi; Mohsen Salahi; Abdurahman Sherif; Pouria Tavakkoli Avval; Suraj Shah; Emil H Schemitsch; Z Shaghayegh Bagheri; Habiba Bougherara; Radovan Zdero Journal: Biomed Res Int Date: 2018-10-18 Impact factor: 3.411
Authors: Daniel Rau; Gabriele Rußow; Mark Heyland; Dag Wulsten; Clemens Kösters; Werner Schmölz; Sven Märdian Journal: J Clin Med Date: 2022-02-08 Impact factor: 4.241