With the recent advances, we have witnessed rapid strides in musculoskeletal oncology. Limb saving surgeries are being done in more than 90% of the malignant bone tumours. This has been attributed to effective chemotherapy, improved imaging modalities, radiotherapy administration, refined surgical techniques and prosthesis constructs. Though limb salvage provides function superior to amputation, it is essential not to leave behind a desensate limb with inadequate motor function. Thus it is very essential to balance oncological clearance and motor functions, which requires a well-coordinated multidisciplinary approach involving varied specialities including a trained orthopaedic oncosurgeon.
A bone with malignant tumors has to be removed surgically and the commonly used modality to fill the gap are metallic prosthesis. They offer immediate stability, mobility and return to function. Earlier these implants would be custom made and prepared size specific to the patient. But now a days, we have modular implants readily available in various sizes. Giving voice to our government’s make in India initiative, we have many low cost locally manufactured prosthesis available. With the advent of bone banks (facilities to store bones) an allograft (bone from bone bank) and prosthesis combinations can be used in specific cases. The biggest challenge in reconstruction is posed while dealing with tumors of children as the bones are in growing phase. The most common solution to this is an “expandable” mega prosthesis. The newer generation expandable prostheses have special mechanisms to lengthen them at periodic intervals by subjecting to a controlled external magnetic field . They provide expansion without doing a surgical procedure on outpatient basis within few minutes . But these are imported implants and are expensive. The Indian alternatives are minimally invasive and need surgery whenever lengthening is needed. Rotationplasty surgery is an excellent alternative to expandable prosthesis but has its own drawbacks such as costemic appearance.
The quest for limb salvage has led to exploring various avenues and the latest one being computer-assisted tumor surgeries under navigation guidance. This is useful while dealing with tumors around the pelvis, sacrum and joint preserving surgeries. The results are encouraging and allows to use customized patient specific implants (PSI) with an aim at saving maximal native bone. 3D printing technology has contributed a lot in this aspect and helps in pre-operative planning and designing customised cutting jigs and implants.
Biological reconstruction is the preferred option whenever feasible. We can use an autograft (patient’s own bone), allograft (bone from bone bank) or re-implantation of sterilized tumor bone (Replacing the patient’s own tumor bone after irradiation or after treatment using liquid nitrogen). Cryotherapy using liquid nitrogen has off late given better results compared to irradiated bones. Autograft reconstruction using buddy/fellow bones in forearm and leg is preferred in reconstructing long segment defects.
At the end of the day the mantra in Orthopaedic oncology is always – “Complete oncological clearance while providing maximum function to the patient”
It is esential you consult a fellowship trained musculoskeletal oncology surgeon who will tell you which the best option suitable for that particular patient is. A wrongly placed biopsy or an improper surgery can lead to an amputation.
Jr. Consultant Orthopedic Oncologist
KIMS Hospitals, Sec-bad.