Relationship between Facet Joint Distraction Distance on CT and Axial Neck Pain after Anterior Cervical Discectomy and Fusion

Chen Hailong; Bai Yunfeng; Li Mingzhe; Liu Jun

Abstract：Objective To investigate the relationship between facet joint distraction(FJD)distance and postoperative axial neck pain in patients undergoing anterior cervical discectomy and fusion(ACDF).Methods A retrospective analysis was conducted on 138 patients[75 males,63 females;mean age(48.1±4.7)years,range 40～55 years]with cervical degenerative disorders treated at the Second Affiliated Hospital of Nanjing Medical University from March 2018 to September 2023.The FJD distance was measured on preoperative and postoperative day 3 cervical CT scans for all patients.These radiographic measurements were then correlated with clinical outcomes.Clinical evaluation included the assessment of neck pain and arm pain intensity using the visual analogue scale(VAS)and functional disability using the neck disability index(NDI),performed both preoperatively and postoperatively.Pearson's correlation coefficient was used to analyze the association between FJD distance and postoperative axial neck pain severity.Furthermore,receiver operating characteristic(ROC)curve analysis was performed to determine the optimal cutoff value for postoperative changes in FJD distance in predicting the occurrence of postoperative axial neck pain.Results All patients completed a minimum postoperative follow-up period of＞12 months.The intensity of neck pain,assessed by VAS,peaked at 3 weeks postoperatively,followed by a progressive decline thereafter.A significant positive correlation was observed between the FJD distance measured on postoperative day 3 and the neck pain VAS scores at 3 weeks postoperatively(r=0.661,P＜0.05).ROC curve analysis demonstrated excellent diagnostic performance for the change in FJD distance in predicting postoperative axial neck pain,with an area under the curve of 0.848[95％CI(0.784,0.911)].The optimal cutoff value for ΔFJD distance was determined to be 1.90 mm.Stratified by the ΔFJD distance cutoff of 1.90 mm,patients were categorized into normal-distraction(ΔFJD＜1.90 mm)and over-distraction(ΔFJD≥1.90 mm)groups.Both groups demonstrated significant improvements in VAS and NDI scores compared to preoperative baselines,with the normal-distraction group achieving statistically superior clinical outcomes across all measures.Conclusion Excessive distraction of the facet joints during ACDF can lead to early postoperative axial neck pain;therefore,surgeons should avoid over-distraction and select an appropriately sized interbody cage to prevent postoperative axial neck pain and adjacent nerve root compression.