RESUMO
AIM: Mega-prostheses required for reconstructing large gaps in bone after limb-saving surgeries for osteo-sarcoma patients have a long development cycle. This includes design of prosthesis components and surgical armamentarium, followed by pilot batch production, lab testing, human clinical trials and regulatory approvals. Most manufacturers stay away due to small market size coupled with the difficulties and high costs involved. Prostheses developed in the West are often unsuitable and unaffordable for the majority of Indian patients. There is a need for high-quality yet low-cost prostheses that are compatible with the anatomy and functionality of local population. METHOD: An inter-disciplinary group comprising orthopedic oncologists, mechanical engineers and materials scientists from three different organizations in India took up the above challenge. They developed a novel modular tumour knee prosthesis with rotating hinge, as well as surgical armamentarium with femoral and tibial cutting jigs and other instruments. Knee simulator and testing machines were developed to test the prosthesis. A dedicated pilot production facility along with inspection and quality management system was set up. RESULT: The new prosthesis provides flexion-extension up to 120 degrees and axial rotation of ±5 degrees. It successfully completed ten million cycles of fatigue and wear testing. The regulatory body of the government and institutional ethical committees of hospitals approved the human clinical trials, which are currently in progress. CONCLUSION: The design, manufacturing and testing of the prosthesis components and armamentarium took more than a decade and presented many challenges. These were overcome by several technological innovations by the engineering team and continuous feedback from the surgeons. The experience is expected to be useful to all others interested in this field.