Objective To investigate the effectiveness of LARS ligament and three-dimensional (3D) printed prosthesis on the combined reconstruction of radial hemicarpal joint after distal radius tumor resection. Methods The clinical data of 12 patients with combined reconstruction of radial hemicarpal joint with LARS ligament and 3D printed prosthesis after distal radius tumor resection between September 2017 and March 2021 were retrospectively analyzed. There were 7 males and 5 females with an average age of 41.8 years (range, 19-63 years). There were 8 cases on the left side and 4 cases on the right side, and 10 cases of giant cell tumor of bone and 2 cases of osteosarcoma. The disease duration ranged from 1 to 20 months, with an average of 8.1 months. The osteotomy length, operation time, and intraoperative blood loss were recorded, and the wrist function was evaluated by Mayo wrist score and Musculoskeletal Tumor Society (MSTS) score before and after operation. The grip strength of the affected limb was expressed by the percentage of grip strength of the healthy upper limb, and the range of motion (ROM) of the wrist joint was measured, including extension, flexion, radial deviation, and ulnar deviation; the bone ingrowth and osseointegration at the bone-prosthesis interface of the wrist joint were observed by radiographic follow-up; the possible wrist complications were recorded. ResultsAll 12 patients successfully completed the operation. The osteotomy length was 5.0-10.5 cm (mean, 6.8 cm), and the operation time was 180-250 minutes (mean, 213.8 minutes). The intraoperative blood loss was 30-150 mL (mean, 61.7 mL). All patients were followed up 11-52 months (mean, 30.8 months). Radiographic follow-up showed that bone ingrowth and osseointegration at the bone-prosthesis interface were observed in all patients, and biological fixation was gradually achieved. During the follow-up, the stability, motor function, and ROM of the wrist joint were good. There was no complication such as arthritis, subluxation, prosthesis loosening, and infection, and no tumor recurrence and metastasis. At last follow-up, the Mayo score was 82.1±5.4, and MSTS score was 27.5±1.5, which were significantly improved when compared with those before operation (48.8±13.5, 16.4±1.4; t=−10.761, P<0.001; t=−26.600, P<0.001). The grip strength of the affected side was 59%-88% of that of the healthy side, with an average of 70.5%. The ROM of wrist joint were 55°-80° (mean, 65.42°) in extension, 35°-60° (mean, 44.58°) in flexion, 10°-25° (mean, 17.92°) in radial deviation, 10°-25° (mean, 18.33°) in ulnar deviation. Conclusion The combined application of LARS ligament and 3D printed prosthesis is an effective way to reconstruct bone and joint defects after distal radius tumor resection. It can improve the function of wrist joint, reduce the incidence of complications, and improve the stability of wrist joint.