nitinol and Radius-Fractures

Shape-memory alloy (SMA) staples are a recent innovation in fracture fixation. These staples have inherent compressive properties that create a stable fracture environment that promotes primary bone healing. They have been used successfully for osteotomies, arthrodesis, and fracture fixation. Understanding where SMA staple compression can be optimized and using proper indications are important for obtaining consistent success and minimizing failures. SMA staples are not a substitute for lag screw fixation or traditional plate and screw constructs.

Topics: Acetabulum; Adult; Alloys; Biomechanical Phenomena; Clavicle; Compressive Strength; Equipment Design; Fracture Fixation, Internal; Fractures, Bone; Humans; Male; Pelvic Bones; Radius Fractures; Sutures; Ulna Fractures

To compare the biomechanical properties of a new nitinol intramedullary (IM) scaffold implant with those of volar plates for the treatment of dorsally comminuted extra-articular distal radius fractures using an established model.. A dorsal wedge osteotomy was performed on a bone model to simulate a dorsally comminuted extra-articular distal radius fracture. This model was used to compare stiffness of 3 different distal radius fixation devices--an IM scaffold implant, a commercially available titanium volar locking plate, and a stainless steel non-locking T-plate. Six constructs were tested per group. Tolerance for physiological loading was assessed by applying 10,000 cycles of axial loading up to 100 N applied at 2 Hz. Axial and eccentric load stiffness were assessed before cyclic loading and axial stiffness again after cyclic loading. Groups were compared using analysis of variance.. Initial axial stiffness (in Newton per millimeter) was significantly (P = 0.011) different only between the volar locking plate (427 ± 43) and non-locking T-plate (235 ± 69). After cyclic loading, axial stiffness was not significantly different between the volar locking plate (392 ± 67) and IM scaffold implant (405 ± 108), but both were significantly (P < 0.001) stiffer than the non-locking T-plate (187 ± 53). Eccentric loading stiffness was not significantly different between the IM scaffold implant (67 ± 140) and volar locking plate (63 ± 5), but both were significantly (P < 0.001) stiffer than the non-locking T-plate (25 ± 4).. Stiffness of the IM scaffold implant and volar locking plate fracture model constructs was equivalent. Biomechanical testing suggests that this novel IM scaffold provides sufficient stability for clinical use, and further testing is warranted.

Topics: Alloys; Biomechanical Phenomena; Fracture Fixation, Intramedullary; Humans; Internal Fixators; Materials Testing; Models, Anatomic; Osteotomy; Palmar Plate; Radiography; Radius; Radius Fractures; Tissue Scaffolds; Weight-Bearing

Shape memory alloys (SMAs) and in particular Ni-Ti alloys are commonly used in bioengineering applications as they join important qualities as resistance to corrosion, biocompatibility, fatigue resistance, MR compatibility, kink resistance with two unique thermo-mechanical behaviors: the shape memory effect and the pseudoelastic effect. They allow Ni-Ti devices to undergo large mechanically induced deformations and then to recover the original shape by thermal loading or simply by mechanical unloading. Diaphyseal fractures of the radius and ulna present specific problems not encountered in the treatment of fractures of the shafts of other long bones. The adaptive modular implants based on smart materials represent a superior solution in the osteosynthesis of the fractured bones over the conventional implants known so far. To realize the model of the implant module we used SolidWorks software. The small sizes of the modules enable the surgeon to make small incisions, using surgical techniques minimally invasive, having the following advantages: reduction of soft tissues destruction; eliminating intra-operator infections; reduction of blood losses; the reduction of infection risk; the reduction of the healing time. Numerical simulations of the virtual modular implant are realized using Visual Nastran software. The stress diagrams, the displacements diagram and the strain diagram are obtained. An in vitro experiment is made, simulating the osteosynthesis of a transverse diaphyseal fracture of human radius bone. The kinematical parameters diagrams of the staple are obtained, using SIMI Motion video capture system. The experimental diagram force-displacement is obtained.

Topics: Alloys; Bone Plates; Fracture Fixation, Internal; Humans; Orthopedics; Radius Fractures

Preparation of the scorpion-like dynamic nitinol osteo-connector (NT-SDOC) and its clinical application in 57 cases were reported. The apparatus was designed with two longitudinal pressure hooks and two to eight semicircular fixation hooks, which could exert an axial continuing stress of 24-56kg on the fracture ends until bone union. Of the 57 cases 31 were fracture and 26 were nonunion, as no plaster cast was applied postoperatively, all patients could exercise their injured arms early. Follow-up was 4 to 32 months with an average of 13.7 months. The osteo-plate substitution was shown at the fracture site at an average of 2.2 months in 31 cases, and at the nonunion site with an average of 3.64 months in 26 cases. No postoperative infection, nonunion and other complications were observed NT-S DOC was removed in 46 cases at about 6 months postoperatively. No refracture occurred at the osteo-plate substitution site.

Topics: Adult; Aged; Alloys; Female; Fracture Fixation, Internal; Fractures, Ununited; Humans; Humeral Fractures; Internal Fixators; Male; Middle Aged; Nickel; Radius Fractures; Titanium; Ulna Fractures