Objective To study the early- and mid-term effectiveness of closed reduction and bilateral bracing using percutaneous pinning supported by adjacent metacarpal bones and a cemented external fixator for treatment of metacarpal shaft fractures. Methods Between April 2022 and June 2024, 18 patients with metacarpal shaft fractures were treated with closed reduction and bilateral bracing fixation using percutaneous pinning supported by adjacent metacarpal bones and a cemented external frame. Of these, 16 were male and 2 were female; their ages ranged from 18 to 47 years (mean, 30.6 years). The time from injury to hospital admission ranged from 1 to 6 days (mean, 3.4 days). Fracture sites were the second metacarpal bone in 5 cases, the fifth metacarpal bone in 10 cases, the fourth and fifth metacarpal bones in 2 cases, and the second to fifth metacarpal bones in 1 case. There were 4 cases of transverse fractures, 10 cases of oblique fractures, and 4 cases of comminuted fractures. The frequency of intraoperative fluoroscopy, operation time, length of hospital stay, time to fracture union, and visual analogue scale (VAS) scores for pain at 1 day before operation and 3 days after operation were recorded. At last follow-up, the range of motion of the metacarpophalangeal joint and the grip strength of the affected hand were measured, and the function of the affected hand was assessed according to the criteria for upper limb functional assessment issued by the Chinese Medical Association Hand Surgery Society. Results The operation time ranged from 38 to 70 minutes (mean, 49.3 minutes); intraoperative fluoroscopy was performed between 4 and 12 times (mean, 6.9 times); and the length of hospital stay ranged from 4 to 9 days (mean, 6.4 days). The VAS score at 3 days after operation was 2 (1, 2), which was significantly lower than the score recorded at 1 day before operation [5 (4, 6)] (Z=?3.866, P<0.001). Three patients experienced slight leakage at the puncture site, and 2 had mild difficulty in extending joints. All patients were followed up 6-8 months (mean, 7.1 months). Imaging follow-up revealed that all fractures had healed, with a healing time ranging from 48 to 72 days (mean, 62.0 days). At last follow-up, the range of motion of the metacarpophalangeal joint was 78°-90° (mean, 86.1°); grip strength in the affected hand reached 80% to 98% of that in the unaffected hand, with a mean of 91.8%. According to the criteria for upper limb functional assessment issued by the Chinese Medical Association Hand Surgery Society, the function was rated as excellent in 6 cases, good in 10 cases, and fair in 2 cases, with an excellent and good rate of 88.9%. Conclusion The treatment of metacarpal shaft fractures using closed reduction and bilateral bracing fixation using percutaneous pinning supported by adjacent metacarpal bones and a cemented external frame offers advantages, such as minimal trauma, relatively simple technique, and ease of internal fixation removal. It yields satisfactory early- to mid-term effectiveness; however, strict adherence to surgical indications is required.