Hybrid fracture fixation systems developed for orthopaedic applications: A general review

Abstract

Orthopaedic implants are applied daily in our orthopaedic clinics for treatment of musculoskeletal injuries, especially for bone fracture fixation. To realise the multiple functions of orthopaedic implants, hybrid system that contains several different materials or parts have also been designed for application, such as prosthesis for total hip arthroplasty. Fixation of osteoporotic fracture is challenging as the current metal implants made of stainless steel or titanium that are rather rigid and bioinert, which are not favourable for enhancing fracture healing and subsequent remodelling. Magnesium (Mg) and its alloys are reported to possess good biocompatibility, biodegradability and osteopromotive effects during its in vivo degradation and now tested as a new generation of degradable metallic biomaterials. Several recent clinical studies reported the Mg-based screws for bone fixation, although the history of testing Mg as fixation implant was documented more than 100 years ago. Truthfully, Mg has its limitations as fixation implant, especially when applied at load-bearing sites because of rather rapid degradation. Currently developed Mg-based implants have only been designed for application at less or non–loading-bearing skeletal site(s). Therefore, after years research and development, the authors propose an innovative hybrid fixation system with parts composed of Mg and titanium or stainless steel to maximise the biological benefits of Mg; titanium or stainless steel in this hybrid system can provide enough mechanical support for fractures at load-bearing site(s) while Mg promotes the fracture healing through novel mechanisms during its degradation, especially in patients with osteoporosis and other metabolic disorders that are unfavourable conditions for fracture healing. This hybrid fixation strategy is designed to effectively enhance the osteoporotic fracture healing and may potentially also reduce the refracture rate.The translational potential of this article: This article systemically reviewed the combination utility of different metallic implants in orthopaedic applications. It will do great contribution to the further development of internal orthopaedic implants for fracture fixation. Meanwhile, it also introduced a titanium–magnesium hybrid fixation system as an alternative fixation strategy, especially for osteoporotic patients.

Biodegradable Magnesium‐Based Implants in Orthopedics—A General Review and Perspectives

“…In addition to aforementioned methods to enhance corrosion resistance and mechanical strength in Mg‐based metals, the development of a Mg‐based hybrid system may be another promising strategy to develop Mg‐containing implants suitable in high weight‐bearing skeletal sites 18,45. Our concept is to combine Mg‐based implants, which promote bone regeneration, with permanent metals that firmly fix fractures in high weight‐bearing skeletal sites 105. As proof‐of‐concept studies, the treatment of challenging bone diseases such as osteoporotic fractures, atypical femoral fractures, and long bone distraction has been tested in animals with innovative Mg‐based hybrid fixators.…”

Multi-Scale Surface Treatments of Titanium Implants for Rapid Osseointegration: A Review

“…In order to overcome this limitation, surface treatment technologies can be used to attain bioactive surfaces on Ti substrates [ 40 , 41 , 42 , 43 ]. The macro-scale, micro-scale, and nano-scale morphology of the implant surfaces have a crucial influence on the early bone formation and fixation [ 16 , 44 , 45 ]. Most titanium implant surfaces with certain roughness characteristics were fabricated through mixed technologies (e.g., grit-blasting, acid-etching).…”

Magnesium and vitamin C supplementation attenuates steroid-associated osteonecrosis in a rat model

“…Stainless steel and titanium are current metals used as bioinert and permeant Class-III implants for orthopaedic applications. Recently, bioactive or biodegradable metals have attracted great attention in research and development (R&D) of biomaterials for clinical applications [1][2][3][4]. Our recent clinical work showed that the bone grafting fixation using biodegradable pure Mg screw was beneficial for successful fixation of bony flap used for treatment of osteonecrosis of the femoral head (ONFH) in patients with steroid-associated osteonecrosis https://doi.org/10.1016/j.biomaterials.2020.119828 Received 4 October 2019; Received in revised form 7 January 2020; Accepted 25 January 2020 (SAON) where bony flap displacement was avoided and local bone density was increased accompanied by Mg-screw degradation, partially explained by the biologic effects of degraded Mg ions, yet like many available related clinical studies the scientific or mechanistic evidence was lacking [5].…”