Preoperative glycated hemoglobin predicts postoperative plantar pressure improvement after posterior cervical laminoplasty in patients with cervical spondylotic myelopathy and diabetes mellitus

BACKGROUND: Diabetes mellitus (DM) may adversely affect neurological recovery after cervical decompression, but its relationship with postoperative plantar pressure restoration in cervical spondylotic myelopathy (CSM) remains insufficiently defined. OBJECTIVE: To evaluate whether preoperative glycated hemoglobin (HbA1c) is associated with postoperative improvement in plantar pressure distribution after posterior single-door laminoplasty in patients with CSM and DM. METHODS: This retrospective single-center study evaluated diabetic patients with CSM treated with posterior single-door laminoplasty and followed for at least 24 months. Dynamic plantar pressure assessment was performed preoperatively and at final follow-up, with medial foot pressure (MFP) and lateral foot pressure (LFP) used as the primary biomechanical outcomes. Linear and logistic regression analyses were used to examine the association between preoperative HbA1c and plantar pressure recovery after adjustment for selected clinical and radiological variables. Receiver operating characteristic (ROC) analysis was performed as an exploratory assessment of discrimination. RESULTS: Postoperatively, plantar loading shifted toward a more physiological distribution, with reduced MFP and increased LFP. Higher preoperative HbA1c was independently associated with smaller improvements in both ΔMFP2 and ΔLFP2 at 2 years. Radiological parameters, including canal narrowing ratio and modified K-line interval, showed associations with outcome in univariable analyses, but their effects were attenuated after adjustment. HbA1c demonstrated fair discriminatory ability for unfavorable plantar pressure recovery, with AUC values of 0.72 for ΔMFP2 and 0.68 for ΔLFP2. CONCLUSIONS: In diabetic patients with CSM undergoing posterior laminoplasty, poorer preoperative glycemic control was associated with less favorable improvement in plantar pressure distribution at long-term follow-up. HbA1c may be useful as one component of preoperative risk stratification within a laminoplasty cohort, but its discriminatory performance was only fair and should not be interpreted as a stand-alone treatment threshold.