Comparison of Three Bone Grafting Techniques in Transoral Atlantoaxial Reduction Plate (TARP) Surgery for Irreducible Atlantoaxial Dislocation

STUDY DESIGN: A retrospective cohort study from a large comprehensive medical center. OBJECTIVES: To compare three bone grafting techniques in transoral atlantoaxial reduction plate (TARP) surgery and provide references for clinical selection. SUMMARY OF BACKGROUND DATA: Irreducible atlantoaxial dislocation (IAAD) is a challenging condition that often requires surgical reduction and stabilization. Although TARP surgery is effective for IAAD, the most appropriate adjunct bone grafting technique remains undetermined. METHODS: Between January 2010 and December 2019, 282 patients with IAAD treated with TARP surgery were enrolled and divided into three groups based on grafting technique. Clinical and radiographic data were retrospectively analyzed, including atlantodental interval (ADI), Visual Analog Scale (VAS), Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), complications and fusion status. RESULTS: All surgeries succeeded with symptom relief. Baseline characteristics, JOA scores, neck pain VAS scores, and NDI were comparable among groups. Postoperative ADI was similar between the morselized and block bone groups, and both were smaller than the cage group (P<0.05). The morselized group showed more obvious ADI loss than the other groups (P<0.05). The fusion cage group had the highest fusion rates at 3- and 6- months follow-up among groups (P<0.05). Block bone presented a higher early fusion rate than morselized bone (P<0.05) but had higher donor-site VAS scores at discharge and 1 month postoperatively (P<0.05). No significant difference was found in postoperative complication rates across the three groups. CONCLUSIONS: Three bone grafting techniques achieved favorable outcomes with distinct profiles. Cage grafting demonstrated superior reduction maintenance and a highest early fusion rate. Morselized and block bone had comparable immediate reduction effects. Block bone yielded better early fusion but caused more severe and prolonged iliac crest donor-site pain. Fusion cage grafting represents a more comprehensive and efficient option. These differences should be fully considered when selecting a grafting technique.