Risk factors for cervical kyphotic deformity following laminoplasty in degenerative cervical myelopathy: A systematic review and meta-analysis.

Postoperative cervical kyphotic deformity (KD) is a recognized complication after laminoplasty for degenerative cervical myelopathy (DCM). This review identified predictors of KD to improve preoperative risk stratification, pooling studies of DCM patients using a random-effects model, with sensitivity and publication bias analyses. Thirty-nine studies (4423 patients) were included, with KD in 20.9% of cases. Age and sex were not significantly associated with KD. Higher body mass index and smoking history showed modest but significant associations. 5-level laminoplasty constructs were associated with increased KD risk, whereas operative time, blood loss, and most construct-related variables were not predictive. Radiographic parameters reflecting sagittal balance and alignment demand demonstrated the strongest associations with KD. Increased T1 slope, greater T1S-cervical lordosis (TS-CL) mismatch, and larger sagittal vertical axis (SVA) measurements (Center of Gravity of Head-C7 SVA and C2-C7 SVA) were significantly associated with KD. Dynamic motion analysis revealed that reduced extension reserve and increased flexion excursion, rather than total range of motion (ROM), characterized higher-risk patients. Magnetic resonance imaging-related factors and thoracolumbar spinopelvic parameters were not significantly associated with KD. Threshold analysis identified CGH-C7 SVA >30.6 mm and extension ROM <11.4° as the most discriminative predictors. Postoperative KD after laminoplasty is primarily determined by preoperative sagittal alignment demand and dynamic motion reserve rather than by general demographics or most comorbidities. Incorporating radiographic and functional parameters - particularly TS-CL mismatch, anterior head translation, and extension reserve - into preoperative evaluation may enhance risk stratification in patients undergoing laminoplasty for DCM.