The optimal cement diffusion pattern in unilateral percutaneous kyphoplasty (PKP) for osteoporotic vertebral compression fractures (OVCFs) remains debated. This multicenter retrospective study investigated whether crossing the vertebral midline with bone cement is necessary under the DGOU classification. A total of 440 patients with single-level OVCFs treated by unilateral PKP (2020–2023) were categorized into OF1, OF2, or OF3 types based on the DGOU classification and further divided into crossing and non-crossing groups according to postoperative CT. Outcomes included VAS, ODI, and radiographic parameters. In OF1 fractures, no significant differences were observed between the two groups. However, for OF2 and OF3 fractures, the crossing group demonstrated significantly better ODI scores at 6 and 12 months (P < 0.001) and improved vertebral height maintenance (P < 0.001), without increasing complications. These findings suggest that achieving cross-midline cement diffusion may not be necessary for stable OF1 fractures, but it is associated with significantly better mid- to long-term functional and radiographic outcomes in unstable OF2/OF3 fracture types.