The clinical diagnosis and treatment of lower limb bone defect is a difficult problem in orthopedics. The traditional treatment has the shortcomings of long treatment period, no weight bearing in the early stage of the limb, weak mechanical strength, many complications, and difficulty in repairing deformed and large segment bone defects around the joint. The Orthopedics Department of Peking University Third Hospital, the lead unit of this study, developed the TCBridge system based on three-dimensional (3D) printing technology in the early stage, which is the first approved 3D printing lower limb long bone defect repair system in China. The system can achieve personalized and accurate repair of lower limb bone defects, and ensure patients to carry out limb weight and functional exercise safely in the early stage after surgery. On this basis, this study will establish a multi-center clinical case cohort to achieve accurate comprehensive diagnosis and treatment of lower limb bone defects, benefiting patients and contributing to society.

Inclusion Criteria:

1. Patients with traumatic lower limb bone defect;
2. Infected lower limb bone defect patients;
3. Patients with neoplastic lower limb bone defect;
4. The above reasons caused bone defects of more than 5CM
5. at least 18 years of age;
6. Sign an informed agreement and join the study cohort voluntarily.

Exclusion Criteria:

1. Patients who do not agree to the use of 3D printed microporous titanium alloy prostheses;
2. Patients who cannot tolerate surgery;
3. the subjects cannot comply with the follow-up or affect the scientific and integrity of the study;
4. Other patients who were not suitable for inclusion as assessed by clinicians.

Patients with lower limb defects