Objective To evaluate the effectiveness of precise orthormorphia of tibial angulation deformity and shortening deformity by using digital technology combined with external fixator. Methods Twenty-six cases of tibial angulation deformity combined with shortening deformity were treated between June 2012 and August 2016, including 12 males and 14 females aged from 1 to 19 years with an average age of 16.5 years. There were 6 cases of congenital patella pseudoarthrosis, 1 case of fibrous dysplasia of femur and tibia, 3 cases of limb shortening deformity caused by infantile paralysis, 16 cases of fracture malunion. Limb shortening was 1.5-9.5 cm (mean, 6.2 cm) before operation. The deformity from three-dimensional perspective was analysed by digital technology, the surgical procedures of lengthening and osteotomy was simulated, the navigation templates were completed with computer aided design (CAD) and three-dimensional printing, and the external fixator was used to assist the lengthening of the tibia. X-ray films were regularly reviewed after operation to observe the new bone remolding, limb lengthening, load bearing line of lower limb, and recurrences of angulation. Results All the patients were followed up 14-48 months (mean, 18.8 months). There was only 1 case of superficial pin site infection which was cured with oral antibiotics and pin site care with mild disinfectants, and no complication such as bone nonunion, equines deformity, or vascular nerve injury occurred. The deformity of tibia and load bearing line of lower limb had been completely recovered according to postoperative X-ray films at 1 week. All the cases achieved perfect limb length as with preoperative design. The bone mineralization time was 12-20 weeks (mean, 11.6 weeks), the external fixator removal time was 18-26 weeks (mean, 14.9 weeks), and the healing index was 21-78 d/cm (mean, 63.4 d/cm). The postoperative flexion range of the injured limb was 15° less than the unaffected extremity in 1 case, and the situation was improved significantly after some physical manipulation and exercise, who completed the limb lengthening and achieved the expected effectiveness finally. Conclusion Precise orthormorphia of tibial deformity by using digital technology, and limb lengthening with the aid of external fixator can achieve good effectiveness with good reliability, invasiveness, and precision.
Objective To investigate the value of computer-aided design (CAD) in defining the resection boundary, reconstructing the pelvis and hip in patients with pelvis tumors. Methods Between November 2006 and April 2009, 5 cases of pelvis tumors were treated surgically using CAD technology. There were 3 males and 2 females with an average age of 36.4 years (range, 24-62 years). The cause was osteosarcoma, giant cell tumor of bone, and angiosarcoma in 1 case, respectively,and chondrosarcoma in 2 cases. According to the Enneking system for staging benign and mal ignant musculoskeletal tumors, regions I, I + II, III, IV, and I + IV is in 1 case, respectively. According to the principle of reverse engineering, 5 patients with pelvis tumors were checked with lamellar CT/MRI scanning, whose two-dimensional data were obtained in disease area. The three-dimensional reconstruction of pelvic anatomical model, precise resection boundary of tumor, individual surgical template, individual prosthesis, and surgical simulation were precisely made by computer with CAD software. Based on the proposal of CAD, the bone tumor was resected accurately, and allograft il ium with internal fixation instrument or allogeneic il ium with personal ized prosthetic replacement were used to reconstruct the bone defect after tumor was resected. Results The operation was successfully performed in 5 cases. The average operation time was 7.9 hours, and the average blood loss was 3 125 mL. Hemorrhage and cerebrospinal fluid leakage occurred in 1 case, respectively, and were cured after debridement. Five patients were followed up from 24 to 50 months (mean, 34.5 months). All patients began non-weight bearing walk with double crutches at 4-6 weeks after operation, and began walk at 3-6 months after operation. Local recurrence developed in 2 patients at 18 months after operation, and resection and radiotherapy were performed. According to International Society of Limb Salvage criteria for curative effectiveness of bone tumor l imb salvage, the results were excellent in 2 and good in 3. Conclusion The individual surgical template, individual prosthesis, and surgical simulation by CAD ensure the precision and rel iabil ity of pelvis tumors resection. The CAD technology promotes pelvis tumor resection and the reconstruction of pelvis to individual treatment stage, and good curative effectiveness can be obtained.