Low Bone Mineral Density as a Risk Factor for Cervical Sagittal Imbalance Following Laminoplasty.

OBJECTIVE

To investigate the influence of preoperative bone mineral density (BMD) on cervical sagittal balance changes following laminoplasty and identify potential risk factors for postoperative cervical sagittal imbalance (CSI).

METHODS

We retrospectively analyzed 104 patients with cervical spondylotic myelopathy (CSM) who underwent multilevel (≥3 levels) cervical laminoplasty between January 2015 and December 2022. Cervical vertebral BMD is measured using computed tomography (CT) and expressed in Hounsfield Units (HU). Patients are divided into deterioration group (final cSVA-baseline cSVA [ΔcSVA]>1 cm, n = 37), stable group (ΔcSVA within ±1 cm, n = 50), and improvement group (ΔcSVA<-1 cm, n = 17) based on postoperative changes in cervical sagittal vertical axis. Ordinal logistic regression analysis is performed to identify risk factors for postoperative CSI.

RESULTS

The deterioration group had significantly lower preoperative mean BMD (261.9±39.2 HU) compared to the stable group (299.0±89.9 HU) and improvement group (345.3±66.1 HU) (P < 0.001). Ordinal logistic regression analysis identified preoperative BMD as an independent risk factor for postoperative CSI. ROC curve analysis determined the optimal BMD threshold value for predicting postoperative CSI is 308.6 HU (sensitivity 85%, specificity 65%).

CONCLUSIONS

Preoperative BMD level is significantly associated with CSI after laminoplasty. Patients with low preoperative BMD (<308.6 HU) are more likely to develop postoperative CSI with poorer clinical outcomes. For patients with preoperative low BMD, laminoplasty should be considered cautiously, with enhanced postoperative management to prevent postoperative CSI.