Clinical efficacy of intra-articular bone grafting of atlantoaxial lateral mass for treating atlantoaxial instability

English Keywords:Atlantoaxial instability  Posterior fusion  Intra-articular bone grafting of the atlantoaxial lateral mass  Posterior structural bone grafting  Height of atlantoaxial lateral mass space

English Abstract:

  【Abstract】 Objectives: To investigate the clinical efficacy of intra-articular bone graft fusion within atlantoaxial lateral mass for the treatment of atlantoaxial instability. Methods: A retrospective analysis was conducted on 49 patients with atlantoaxial instability who underwent posterior atlantoaxial fusion with screw fixation and bone grafting at the Department of Orthopedics, Changzheng Hospital, Naval Medical University from January 2016 to December 2019. There were 17 males and 32 females, aged from 8 to 72 years(45.2±17.1 years). All the patients were treated with posterior atlantoaxial fixation with pedicle screw-rod system, and were divided into two groups based on the bone grafting method: group A comprised 28 patients who underwent posterior structural bone grafting between the posterior arch of atlas and the lamina of axis from January 2016 to December 2018, including 9 males and 19 females, with a mean age of 42.1±20.2 years; group B consisted of 21 patients who underwent intra-articular bone grafting in the atlantoaxial lateral mass from January 2018 to December 2019, comprising 8 males and 13 females, with a mean age of 49.3±19.8 years. The operative time, intraoperative blood loss were collected, and Japanese Orthopaedic Association(JOA) score, neck disability index(NDI) and visual analogue scale(VAS) of neck pain were compared between the two groups before operation and at the last follow-up. The height of the atlantoaxial lateral mass space was measured on the coronal CT before operation, right after operation, and at the last follow-up, and the fusion status of bone graft was observed. Results: There were no statistically significant differences in age, gender, and types of diseases between the two groups of patients(P>0.05), indicating comparability. Both groups of patients successfully completed the surgery without any injury to the vertebral artery or nerves. The intraoperative blood loss in group A was significantly less than that in group B(210.2±26.6mL vs 230.5±6.2mL, P<0.05). There were no statistically significant differences between the two groups in terms of operative time and follow-up duration(P>0.05). The JOA scores, NDI, and VAS scores of both groups showed significant improvement compared to preoperative values at the last follow-up, respectively(P<0.05), while no statistical differences were observed between the two groups at the same time point(P>0.05). The space height of atlantoaxial lateral mass of group A wasn′t significantly different from that of group B before surgery(P>0.05), it was significantly lower than that of group B immediately after surgery(P<005), which was still lower than that of group B at the last follow-up, although both groups experienced varying degrees of collapse(P<005). All the patients achieved bone fusion, and there was no statistically significant difference in the fusion time between the two groups(P>0.05). During the follow-up period, no complications such as screw loosening, displacement, or fracture were observed. Conclusions: In posterior atlantoaxial screw-rod fixation surgery, utilizing intra-articular bone grafting of the atlantoaxial lateral mass can achieve favorable bone fusion, which can be employed in patients with conditions such as posterior arch defects where traditional atlantoaxial structural bone graft fusion surgery is not feasible. Intra-articular bone grafting of the atlantoaxial lateral mass helps to avoid complications associated with harvesting autologous iliac bone grafts, such as pain and infection; Furthermore, it can maintain the height of the atlantoaxial facet joint space to a certain extent, thereby enhancing stability.