End-to-end suture of nerves and autologous nerve grafts are the ‘gold standard’ for repair and reconstruction of peripheral nerves. However, techniques such as sutureless nerve repair with tissue glues, end-to-side nerve repair and allografts exist as alternatives. Biological and synthetic nerve conduits have had some success in early clinical studies on reconstruction of nerve defects in the hand. The effectiveness of nerve regeneration could potentially be increased by using these nerve conduits as scaffolds for delivery of Schwann cells, stem cells, neurotrophic and neurotropic factors or extracellular matrix proteins. There has been extensivein vitroandin vivoresearch conducted on these techniques. The clinical applicability and efficacy of these techniques needs to be investigated fully.
Chondral and osteochondral defects in the knee are common and may lead to degenerative joint disease if treated inappropriately. Conventional treatments such as microfracture often result in fibrocartilage formation and are associated with inferior results. Additionally, microfracture is generally unsuitable for the treatment of defects larger than 2–4 cm2. The osteochondral autograft transfer system (OATS) has been shown to produce superior clinical outcomes to microfracture but is technically difficult and may be associated with donor-site morbidity. Osteochondral allograft use is limited by graft availability and failure of cartilage incorporation is an issue. Autologous chondrocyte implantation (ACI) has been shown to result in repair with hyaline-like cartilage but involves a two-stage procedure and is relatively expensive. Rehabilitation after ACI takes 12 months, which is inconvenient and not feasible for athletic patients. Newer methods to regenerate cartilage include autologous stem cell transplantation, which may be performed as a single-stage procedure, can have a shorter rehabilitation period and is less expensive than ACI. Longer-term studies of these methods are needed. Cite this article: EFORT Open Rev 2020;5:156-163. DOI: 10.1302/2058-5241.5.190031
Tissue engineering of bone has the potential to overcome the limitations of using autologous, allogeneic or synthetic bone grafts to treat extensive bone defects. It involves culturing of osteogenic cells within appropriate scaffold materials under conditions that optimize bone development. Stem cells, progenitor cells, terminally differentiated cells or genetically modified cells may be used. Scaffold materials include polymers, ceramics or composites which are used to maintain the desirable characteristics of the individual materials. Preclinical and clinical studies on the use of growth factors such as bone morphogenetic proteins to increase bone formation have had promising results. This review discusses the approaches to and the challenges associated with producing tissue engineered bone.
SLS porous collars allow the direct ingrowth of more bone and are better than current designs which rely on surface ongrowth and ECBB. Cite this article: Bone Joint J 2017;99-B:276-82.
With an increasing body of evidence in non-human and in vitro studies, more human trials are required. More high level studies with extensive and robust validated reporting methods should be conducted to evaluate the true effect of such techniques in human cartilage defect repairs.
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