Stress-Shielding Effect of Nitinol Swan-Like Memory Compressive Connector on Fracture Healing of Upper Limb

Abstract

In this article, the stress-shielding effect of a Nitinol swan-like memory compressive connector (SMC) is evaluated. Patients with fracture healing of an upper limb after SMC internal fixation or stainless steel plate fixation were randomly selected and observed comparatively. With the informed consent of the SMC group, minimal cortical bone under the swan-body and swan-neck was harvested; and in the steel plate fixation group, minimal cortical bone under the steel plate and opposite side to the steel plate was also harvested for observation. Main outcome measurements were taken such as osteocyte morphology, Harversian canal histological observation under light microscope; radiographic observation of fracture healing, and computed tomography quantitative scanning of cortical bone. As a conclusion, SMC has a lesser stress-shielding effect to fixed bone than steel plate. Finally, the mechanism of the lesser stress-shielding effect of SMC is discussed.

Authors’ reply to comments by Sharma et al. on the article by Su JC et al.: Shape memory Ni-Ti alloy swan-like bone connector for treatment of humeral shaft nonunion

“…Relatively speaking, the SMC is protective of blood supply compared with steel-plate fixation, which is much longer. SMC size is based on full consideration of the humeral bone anatomy and biomechanical features, with a diameter/axial length ratio of around 1:6 [3,4]. Generally, postoperative supplementary stabilisation is not needed.…”