Megaprosthesis in post-traumatic and periprosthetic large bone defects: Issues to consider

The recent evolution of prosthesis technology has enabled the surgeon to replace entire limbs. These special prostheses, or megaprostheses, were developed for the treatment of severe oncological bone loss; however, the indications and applications of these devices have expanded to other orthopaedic and trauma situations. For some years, surgeons have been implanting megaprostheses in non-oncological conditions, such as acute trauma in severe bone loss and poor bone quality; post-traumatic failures, both aseptic and septic (represented by complex non-unions and critical size bone defects); major bone loss in prosthetic revision, both aseptic and septic; periprosthetic fractures with component mobilisation and poor bone stock condition. The purpose of this study was to evaluate retrospectively the complications during and after the implantation of megaprosthesis of the lower limb in post-traumatic and prosthetic bone loss, and to propose tips about how to avoid and manage such complications.

All the complications and difficulties we have encountered during or after the implantation of megaprosthesis in non-oncology patients were evaluated retrospectively. A total of 72 patients were treated with large resection mono-and bi-articular prostheses between January 2008 and January 2014.

The main critical problems found in the study were: restoration of the correct length and rotation of the limb; reconstruction of the knee extensor mechanism; trochanteric reconstruction; stability/dislocation of the implant; mobility/range of motion (ROM) of the implant; skin cover; sepsis, and bone quality.

Megaprosthesis in severe bone loss can be considered as an available solution for the orthopaedic surgeon in extreme, appropriately selected cases. This type of complex surgery must be performed in specialised centres where knowledge and technologies are present. Patients with severe bone loss should not be treated in the same way as oncology patients because life expectancy is definitely longer; therefore, the surgical technique and the system implantation must be extremely rigorous to ensure longevity of the prosthesis. The characteristics of the bone and soft tissue conditions in these patients are very different from those presented by oncology patients, which creates critical problems that the surgeon should be able to manage to avoid serious complications.