An allograft prosthetic composite is a combination bone graft and metal implant.  Another method of limb-salvage surgery, it involves inserting a prosthesis into a donor bone segment, which is then inserted in place of the patient's own cancerous bone.  This has several potential advantages.  The donor bone, or allograft, provides a place to attach tendons, while the implant provides a sturdier joint.  One of the main benefits is that the physician can customize the procedure specifically for the patient.

Like all procedures, however, an allograft prosthetic composite can result in complications.  Infections cause many failures.  Non-union may occur, in which the bones do not heal together properly.  This increases a patient's chance of suffering a fracture.  Also, the implant may begin to wear out over time, which requires surgery to either fix or replace.  When the procedure is performed on children, it may cause one limb to be significantly shorter than the other.  Surgery is also required in these cases.  

The proximal femur and the proximal tibia (the top of the thigh bone and the top of the shin bone, respectively) are the usual sites where an allograft prosthetic composite is most effective.  However, infections are much more likely to occur in a composite reconstruction.

Source:
DiCaprio, Matthew R., M.D., and Gary E. Friedlaender, M.D.  (2003, January/February.)  Malignant Bone Tumors: Limb Sparing Versus Amputation. Journal of the American Academy of Orthopaedic Surgeons, 11(1), 25 - 37.

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