Background <p>Ulnar shortening osteotomy (USO) is a standard surgical treatment for ulnar impaction syndrome. This study introduces a modified ulnar metaphyseal wedge osteotomy (MUMWO) and compares its outcomes with conventional diaphyseal ulnar shortening osteotomy (DUSO). </p> Methods <p> In this retrospective cohort study, we compared postoperative functional outcomes and operative characteristics between patients undergoing traditional diaphyseal ulnar shortening osteotomy (n=18) and those receiving our modified ulnar metaphyseal wedge osteotomy (n=13) for treatment of ulnar impaction syndrome.</p> Results <p> No differences were observed in patients characteriscs, ulnar variance, pain and functional score between two groups at the baseline. Patients underwent modified ulnar metaphyseal wedge osteotomy showed significant improvements in pain, Quick-DASH scores, wrist extension, wrist flexion, supination, and pronation (All <i>P</i>≤ 0.001). Compared to diaphyseal ulnar shortening osteotomy, modified ulnar metaphyseal wedge osteotomy was associated with less degree of ulnar shortening, shorter surgery time, and reduced intraoperative blood loss (All<i> P </i>&lt; 0.05). After adequate follow-up time, modified ulnar metaphyseal wedge osteotomyshowed lower rate to remove implants, greater improvement in pain and Quick-Disability of the Arm, Shoulder, and Hand questionnaire scores (Both <i>P</i>&lt;0.001).</p> Conclusions <p> Modified ulnar metaphyseal wedge osteotomy of the ulnar shaft and epiphysis optimizes the osteotomy plane and angle, allowing for precise decompression while preserving sufficient bone mass. These biomechanical advantages contribute to better early functional recovery and reduced surgical trauma. However, its potential role in delaying DRUJ degeneration and other complications requires further validation through more large-scale, randomized clinical trials.</p>