Repair of large skeletal defects that are intrinsic to skeletal stability represents the greatest challenge for orthopaedic surgeons.
IntroductionBone defects arising from disease, trauma, infection or genetic abnormality are reconstructed with non-biodegradable materials such as stainless steel or titanium to restore skeletal function.
2,3These materials have been associated with long-term problems such as loosening, 4 peri-prosthetic fracture and infection.
5The modern approach is marked by a shift in emphasis from replacement to regeneration of tissue. 6,7 This is achieved by way of human-or animal-derived grafts (autograft, allograft or xenograft), bone graft substitute (BGS) materials, growth factors 8 or bioinorganics. 9 The drawbacks associated with human-and animal-derived grafts such as limited availability, high cost, poor remodelling, donor site morbidity, delayed healing and disease transmission have driven extensive research into synthetic alternatives. [10][11][12][13] The principal advantages of BGSs are unlimited supply, ease of sterilisation and storage, predictable mechanical properties, excellent bone in-growth and moderate cost. 14,15 Bone defects can be categorised into those that are intrinsic to skeletal stability and those that are not. Currently, there are numerous commercially available low-strength, void-filling BGS products but none are indicated to offer structural support to the skeleton. [16][17][18] Thus, there is an urgent need for BGSs that can replace allogenous or autogenous grafts in large defects, for example, in resections for infection or tumour. In these instances, bone grafts can be as large as 20 cm and their locations (joints, spine and long bones) require them to bear load and function with instrumentation to maintain the stability of the skeleton.2,19-21 Non-structural biomaterials can repair segmental defects in combination with instrumentation such as plates and screws but these require an additional retrieval procedure.22 A BGS material with the strength of cortical bone will benefit many patients and be particularly useful in spinal arthrodesis where high strength and osteoinductivity are essential to ensure rapid fusion.
23,24High-strength scaffolds for bone regeneration Meredith and Mallick