Tumour Endoprosthetic Reconstruction in Sarcoma ?

(Tumour Arthroplasty/ Megaprosthetic reconstruction)

A megaprosthesis/endoprosthesis is a large metallic device designed to replace the excised length of bone and the adjacent joint. Presently, modular designs which allow great degree of freedom for surgeon to assemble the prosthesis intra-operatively and result in excellent reconstruction specific to needs of the patient are available along with custom made designs

The prosthetic joint is of fixed or modified hinge design to substitute for the stability normally provided by the capsular and ligamentous structures that were sacrificed by the sarcoma removal. The prosthesis is fixed to the host bones with or without polymethylmethacrylate cement depending on age, bone involved and strength of the host bone. Special attention is paid during closure to ensure that the prosthesis is fully covered by a healthy muscle and soft tissue envelope. This provides the reconstruction immediate stability and allows rapid mobilization of the patient following surgery.                 

Chondrosarcoma (clear cell variant) of proximal femur, Bipolar tumour megaprosthesis

What is Expandable Megaprosthesis/ Endoprosthesis?

Children in age group between 6 – 16 years have growth potential. Removal of sarcoma usually involves adjacent growth plate removal which results in short limb. Advancements in Endoprosthetic designs have allowed expandable endoprosthesis in children which allow lengthening in stages. The endoprosthesis are custom made and fixed specifically based on age and remaining host bone and growth potential. They incorporate a mechanism which allows expansion or lengthening either in invasive or non-invasive manner. Invasive manner requires the child to be admitted for one day and the endoprosthesis is lengthened manually by a small incision under anesthesia. On the contrary, non-invasive method involves placement of the limb in a specifically designed magnetic coil and lengthened by the mechanism without need for any intervention. These are performed in regular interval of 6 months or more depending on remaining growth.

 

                                        Osteosarcoma limb salvage Tumour megaprosthesis

What are the complications involved in megaprosthetic/ endoprosthetic reconstruction?

Components of arthroplasty undergo phenomenon of wear and tear in the body gradually until the components degrade and require to be changed.

Complications associated with megaprosthetic/endoprosthetic reconstructions are as follows in decreasing order:

  • Deep periprosthetic infection
  • Failure of muscle and soft tissue cover
  • Aseptic loosening, fracture of components, wear of bushing
  • General complications involved in all major limb and pelvic surgeries such as neurovascular injury, deep vein thrombosis, pulmonary embolism, tourniquet related complications and extensive blood loss intra or post operative.
  • Local Recurrence