Objective To explore the effects of nail-tail transverse connection in the treatment of atlantoaxial dislocation (AAD) and its impacts on bone metabolism, serum vascular endothelial growth factor (VEGF), and fibroblast growth factor-2 (FGF-2) levels.

Methods A total of 150 patients with AAD were selected as the research subjects and divided into two groups using the random number table method, with 75 cases in each group. The observation group was treated with nail-tail transverse connection combined with posterior atlantoaxial pedicle screw internal fixation (C1-C2 PSR), while the control group was treated with C1-C2 PSR alone. Serum bone metabolism indicatorsosteocalcin (BGP), type Ⅰ collagen N-terminal peptide (NTX), bone alkaline phosphatase (BALP), tartrate-resistant acid phosphatase (TRAP), type Ⅰ collagen carboxy-terminal peptide (CTX), VEGF and FGF-2 levels were compared between the two groups at different time points. The Japanese Orthopaedic Association (JOA) score was used to evaluate the patients' neurological function before surgery and 3 years after surgery. Bone graft fusion was evaluated at 6 months, 1 year, 2 years, and 3 years after surgery.

Results At 1, 3 and 6 months after surgery, the serum VEGF and FGF-2 levels in the observation group were higher than those in the control group, and the differences were statistically significant (P < 0.05). After treatment, the BALP, BGP, NTX, TRAP and CTX levels in both groups were lower than those before treatment, and their levels in the observation group were lower than those in the control group, with statistically significant differences (P < 0.05). Before surgery, there was no statistically significant difference in the JOA scores between the two groups (P>0.05). At 3 years after surgery, the JOA scores in both groups were higher than those before surgery, and the JOA score and the score improvement rate in the observation group were higher than those in the control group, with statistically significant differences (P < 0.05). At 6 months, 1 year, 2 years and 3 years after surgery, the success rate of bone graft fusion in the observation group was higher than that in the control group, with statistically significant differences (P < 0.05).

Conclusion Nail-tail transverse connection has significant effects in the treatment of AAD, which can effectively improve patients' bone metabolism and increase the serum VEGF and FGF-2 levels.