Cancer growth in the bone due to its random shape disables bone strength and thus changes its capacity to support body weight or muscles, which can crucially affect the quality of human life in terms of normal walking or daily activities. For successful patient recovery, it is necessary to remove the cancer-affected minimal bone area and quickly replace it with a biocompatible metal implant within less than 2 weeks. An electron beam-melted Ti-6Al-4V implant was designed and applied in a patient to preserve the natural knee joint close to the bone tumor. The developed implant fits the bone defect well, and the independent ambulatory function of the natural knee joint was restored in the patient within six weeks after surgery. A delayed fracture occurred six months after the successful replacement of cancer-affected bone with Ti-6Al-4V implant at the proximal meshed junction of the implant because of a minor downward slip. Microstructural, mechanical, and computational analyses were conducted for the fractured area to find the main reason for the delayed fracture. Our findings pertaining to the mechanical and material investigation can help realize the safe implantation of the three-dimensionally printed titanium implant to preserve the natural joints of patients with massive bone defects of the extremities.

Bone replacement implants manufactured by electron beam melting have been widely studied for use in bone tumor treatment. In this application, a hybrid structure implant with a combination of solid and lattice structures guarantees strong adhesion between bone and soft tissues. This hybrid implant must exhibit adequate mechanical performance so as to satisfy the safety criteria considering repeated weight loading during the patient’s lifetime. With a low volume of a clinical case, various shape and volume combinations, including both solid and lattice structures, should be evaluated to provide guidelines for implant design. This study examined the mechanical performance of the hybrid lattice by investigating two shapes of the hybrid implant and volume fractions of the solid and lattice structures, along with microstructural, mechanical, and computational analyses. These results demonstrate how hybrid implants may be designed to improve clinical outcomes by using patient-specific orthopedic implants with optimized volume fraction of the lattice structure, allowing for effective enhancement of mechanical performance as well as optimized design for bone cell ingrowth.