Efficacy of occipitocervical fusion with the occipital screw-rod-multiaxial screw internal fixation system in the treatment of "sandwich" deformity with atlantoaxial dislocation

English Keywords:Atlantoaxial dislocation  "Sandwich" deformity  Occipital plate-rod-multiaxial screw system  Occipital screw-rod-multiaxial screw system  Bone graft fusion area

English Abstract:

  【Abstract】 Objectives: To investigate the clinical efficacy of occipitocervical fusion with the occipital screw-rod-multiaxial screw internal fixation system in treating "sandwich" deformity with atlantoaxial dislocation. Methods: A retrospective analysis was conducted on 62 patients who underwent posterior reduction, bone graft fusion, and occipitocervical internal fixation for "sandwich" deformity with atlantoaxial dislocation from January 2017 to January 2023. There were 19 males and 43 females, aged 51.1±23.5 years(29-72 years). The patients were divided into two groups based on the different fixation methods of the occipital screws used in the two types of occipitocervical internal fixation systems: group A of 38 patients utilized the occipital screw-rod-multiaxial screw system, consisting of 12 males and 26 females, aged 50.9±24.8 years(29-72 years), and the imaging findings revealed brainstem or cervical spinal cord compression in 30 cases, syringomyelia in 6 cases, and Chiari malformation in 2 cases; And group B of 24 cases utilized the occipital plate-rod-multiaxial screw system, consisting of 7 males and 17 females, aged 51.4±22.4 years(32-69 years), and the imaging findings revealed brainstem or cervical spinal cord compression in 16 cases, syringomyelia in 6 cases, and Chiari malformation in 2 cases. Group A was followed up for 36.5±11.8 months and Group B was followed up for 36.1±9.8 months. No statistically significant differences were observed between the two groups in terms of age, sex, imaging findings, or surgery style(P>0.05). A comparison was performed between the groups regarding intraoperative blood loss, operative time, follow-up period, and complication rates. Clinical outcomes were evaluated preoperatively and at the final follow-up using the neck pain visual analog scale(VAS) score, neck disability index(NDI), and Japanese Orthopaedic Association(JOA) score. The cross-sectional and sagittal bone fusion area of the graft site, atlantodental interval(ADI), space available for cord(SAC), clivus canal angle(CCA), and cervico-medullary angle (CMA) were measured preoperatively, 1 week postoperatively, and at the final follow-up in both groups. Results： Group A and group B weren′t significantly different in intraoperative blood loss(362.4±89.1mL vs 345.1±93.8mL, P>0.05) and operative time(144.8±35.6min vs 143.7±36.2min, P>0.05). In group B, rod fractures occurred in 2 cases and loss of reduction was observed in 3 cases, whereas the remaining patients maintained stable screw-rod fixation. Neither group experienced severe complications such as spinal cord injury or cerebrospinal fluid leakage. Both groups demonstrated statistically significant differences between preoperative NDI, VAS, JOA scores and those measured at the final follow-up(P<0.05), while no statistically significant differences existed between the two groups at the same time points(P>0.05). Statistically significant differences were observed between preoperative and postoperative(1-week and final follow-up) measurements for ADI, SAC, CCA and CMA in both groups(P<0.05), while no significant intergroup differences were found at corresponding time points(P>0.05). In group A, the cross-sectional area and the sagittal area of the graft site were 385.44±84.51mm2 and 290.28±110.41mm2 in postoperative 1 week, and 267.06±66.13mm2 and 204.54±83.85mm2 at the final follow-up; which in group B were 442.61±76.85mm2 and 267.21±104.63mm2 in postoperative 1 week, and 172.43±37.37mm2 and 124.87±48.10mm2 at final follow-up. Comparisons between groups revealed no statistically significant differences in either cross-sectional or sagittal graft areas at 1 week postoperatively(P>0.05), however, significant differences were observed at the final follow-up(P<0.05) for both parameters between the two groups. Conclusions: The occipital screw-rod-multiaxial screw internal fixation system presents comparable restoration effects to the occipital plate-rod-multiaxial screw system in treating "sandwich" deformity with atlantoaxial dislocation. It exhibits satisfactory implant fusion postoperatively and achieves reliable occipitocervical fixation.