Purpose <p>Some cases of isolated unstable Jefferson’s fracture of the Atlas verbebra require surgical fixation. Historical constructs with occipitocervical fixation or C1C2 posterior Harms-Goel fixation remain associated with functional impairment owing to limited postoperative cervical range of motion. Since 2004, motion-preserving C1 ring lateral mass screws with transverse rod (C1 LMF) has emerged as a possible technical alternative.</p> Methods <p>Retrospective multicentric study of patients operated on for isolated unstable Jefferson’s fracture of the Atlas vertebra using C1 LMF in two tertiary referral hospitals from South France.</p> Results <p>Since 2022, 9 patients (mean age 52.2 ± 20.5, male/female 7/2) were operated on by 5 different senior spine surgeon for Jefferson type 3 (6 cases) or type 4 (3 cases), with 8 cases of transverse ligament injury. Seven patients were treated in the acute setting (mean 2.9 ± 1.2 days), two patients were treated for chronic pseudarthrosis (mean 157.5 ± 116.7 days). Mean operative time was 108.7 ± 45.3&#xa0;min with intraoperative blood loss of 233.3 ± 106.1, guided either by fluoroscopy (6 cases) or spinal navigation (3 cases). One patient had both screws misplaced medially without clinical consequence, requiring revision surgery. After a mean follow-up of 15.7 ± 7.8, self-assessed clinical outcome was excellent (VAS 1.3 ± 1.2, NDI 17.6 ± 8.9) with good cervical motion (rotation 57.8 ± 12.5°) and 66.7% of return-to-work. Bone fusion was achieved in 77.8%, with lateral mass distance reduction from 11.1 ± 3.6&#xa0;mm down to 6.8 ± 3.3&#xa0;mm.</p> Conclusion <p>This small patient series suggests the long-term efficacy as well as the operative safety of C1 LMF for isolated unstable Jefferson’s fracture.</p>