Indications for Nonbiological Reconstruction of Posttraumatic Bone Defects About the Knee

SUMMARY

3D printing and modeling has continued to grow in popularity over the past decade because the technology has matured and become more affordable and widely available. The main indications for nonbiological reconstruction of large bone defects are principally those patients where the candidate is unlikely to be successful if reconstructed by other means. Bespoke, custom, patient-specific implants can be designed to very effectively address bone loss, incorporating design elements that are particular to the needs of any given unique clinical condition. These implants are generally designed as titanium scaffolds that encourage bony incorporation at the host implant junction both proximal and distal. These scaffolds are typically considered a cellular solid, with high porosity that also promotes bone ingrowth directly into the substance of the body of the implant. Titanium scaffolds of this type have become a useful treatment alternative for large segmental bone defects around the knee, especially distal femoral defects. These are often adult patients with local or systemic compromise, or instead they may be too young to be considered candidates for reconstruction using a megaprosthesis. The process requires careful evaluation of individual patients, then matching that patient with the best treatment option, while recognizing the expectations and demands specific to that particular patient. Several cases are presented here to illustrate the variety of indications that can be successfully addressed with this technology, highlighting the quality of the clinical outcome that can be achieved despite the complexity of the pathology encountered.

Putting 3D modelling and 3D printing into practice: virtual surgery and preoperative planning to reconstruct complex post-traumatic skeletal deformities and defects

3D printing technology has revolutionized and gradually transformed manufacturing across a broad spectrum of industries, including healthcare. Nowhere is this more apparent than in orthopaedics with many surgeons already incorporating aspects of 3D modelling and virtual procedures into their routine clinical practice. As a more extreme application, patient-specific 3D printed titanium truss cages represent a novel approach for managing the challenge of segmental bone defects. This review illustrates the potential indications of this innovative technique using 3D printed titanium truss cages in conjunction with the Masquelet technique. These implants are custom designed during a virtual surgical planning session with the combined input of an orthopaedic surgeon, an orthopaedic engineering professional and a biomedical design engineer. The ability to 3D model an identical replica of the original intact bone in a virtual procedure is of vital importance when attempting to precisely reconstruct normal anatomy during the actual procedure. Additionally, other important factors must be considered during the planning procedure, such as the three-dimensional configuration of the implant. Meticulous design is necessary to allow for successful implantation through the planned surgical exposure, while being aware of the constraints imposed by local anatomy and prior implants. This review will attempt to synthesize the current state of the art as well as discuss our personal experience using this promising technique. It will address implant design considerations including the mechanical, anatomical and functional aspects unique to each case.