What is Biological reconstruction?
Reconstruction of the defect after removal of sarcoma is performed with either host bone (Allograft or Autograft/Tumor Autograft) leads to more biological response and healing and avoids complications associated with endoprosthetic reconstructions. These grafts can be utilized in procedures such as Intercalary reconstruction (which saves the adjacent joints), arthrodesis or in joint reconstructions (Osteo-articular).
In what ways can biological reconstruction be performed?
What is Arthrodesis?
Bridging the defect above and below the joint by combination of graft and metal implants results in stiff but stable limb. The motion at the native joint is lost in arthrodesis. In case of lower limb, the affected limb will be shortened by 2-3 cms to aid walking. This option is provided when the individual requires to perform high demand, heavy labor or manual work at the expense of joint mobility.
What is Intercalary reconstruction?
A sarcoma which involves the shaft of long bone and spares the joint can be completely removed and the defect can be reconstructed in biological method or by segmental modular spacer implants.
Options for Biological reconstruction are Massive bone allograft, Vascularized fibula, Recycled Tumor Autograft (ECRT/Cryotherapy) and Osteo-Articular allograft.
After the tumor resection, the Massive bone allograft that has been carefully size-matched to the intended recipient is cut to the appropriate shape. The shaft of the allograft is fixed to the end of the host bone with a bone plate or an intramedullary rod with screws.
For Osteoarticular allograft reconstructions of a joint, massive bone allograft with intact joint capsule and ligaments that matches the articular size and geometry of the resected specimen as closely as possible is selected. The capsule and ligaments of the allograft are attached to their counterparts on the host bone. Muscle insertions are repaired to the stumps of tendons on the allograft. This procedure prevents usage of metal in the joint. Major disadvantage is the degeneration of joint surface over short period of time requiring endoprosthetic reconstruction.
Recycled Tumour Graft/Tumor Autograft (ECRT) is performed when the host bone involved with sarcoma has adequate structural integrity and strength maintained (i.e. the tumor has involved the bone but not weakened it completely to replace with other methods). The removed host bone is stripped of any soft tissue attachment and subjected to 50 Cgy of radiation in sterile environment. The medullary canal is cleared and the ECRT graft is washed and placed in antibiotic solution prior to reimplantation with help of plate and screws. The advantage in this procedure is the host bone is reinserted and does not need the careful planning required in massive bone allografts and associated complications. The risk of local recurrence is less than 1 -2 %.
Fibula Autograft is a very useful and expendable bone in the leg. Adequate lengths of fibula are harvested from the patients same or opposite leg to help in reconstruction. For defects ≤ 10 cms fibula is harvested and placed in defect alone or in combination with allograft. For defects ≥ 10 cms, the fibula is harvested usually from opposite leg with periosteum and blood vessels supply intact (Vascularized Fibula). This is then anastomosed in the recipient area with a host blood vessel and used alone or in combination with massive bone allograft. Advantages of vascularized fibula are easy transport to any defect in the body, biological reconstruction, less risk of graft failure complications due to intact blood supply and potential for overgrowth of the fibula in reconstructions.
What are complication of Biological Reconstruction?
Common complications of any graft usage are delayed union, mal-union, non-union, graft fracture followed by infection, implant breakage, and graft resorption and adjuvant treatment with chemotherapy and radiation increase the complication rate.
There is a theoretical risk of transmission of viral infections such as HIV, Hepatitis B & C which is negligible since the allograft is stored in freezer at minus 80 degree Celsius and radiated which kill the virus. It is rare to find graft rejection since the allograft has lost all its reactive immune properties.