Quantifying Postural Recovery After Lumbar Decompression: Cone of Economy Biomarkers of Balance Effort and Stability in Patients with Radiculopathy and Neurogenic Claudication.

Abstract

Degenerative lumbar spine pathology manifesting as radiculopathy and neurogenic claudication often leads to impaired postural stability, compensatory movement strategies, and increased fall risk. Conventional clinical assessments and patient-reported outcomes inadequately characterize dynamic balance dysfunction and postural control deficits that persist after surgical intervention. To objectively quantify changes in postural stability, balance effort, and Cone of Economy (CoE) control following lumbar decompression surgery in patients with radiculopathy and neurogenic claudication using high-resolution three-dimensional motion analysis. Prospective, single-center cohort study. Thirty-six adults (mean age 70.1 ± 11.4 years) with symptomatic degenerative lumbar spinal stenosis undergoing open decompression surgery. Postural sway and stability metrics, including CoE dimensions, center-of-pressure (CoP) and center-of-mass (CoM) excursion, sway path and velocity, phase-plane stability, frequency-domain characteristics, and joint-level compensatory excursions, along with patient-reported outcomes (Oswestry Disability Index, PROMIS, Tampa Scale of Kinesiophobia). Participants completed standardized three-dimensional balance assessments one week before and three months after decompression using a 41-marker motion capture system synchronized to dual force plates. Mixed-effects models tested pre- to postoperative changes, accounting for age, BMI, and repeated measures with false discovery rate correction for multiple comparisons. Lumbar decompression was associated with significant improvements in mediolateral postural control. Center-of-pressure mediolateral sway decreased from 2.24 ± 0.92 cm to 1.70 ± 0.69 cm (p = 0.007), head coronal sway from 3.29 ± 1.11 cm to 2.38 ± 0.87 cm (p = 0.001), and CoM coronal sway from 1.85 ± 0.74 cm to 1.40 ± 0.63 cm (p = 0.009). Expanded balance metrics demonstrated reductions in total head sway path area (9.55 ± 3.12 → 6.47 ± 2.41; p = 0.001), improved phase-plane stability (p < 0.001), and decreased low- and mid-frequency sway power (p ≤ 0.014). Compensatory strategies at the cervical spine, lumbar coronal motion, pelvis, and hips were significantly reduced postoperatively, while knee and ankle kinematics were maintained. Patient-reported disability and pain interference improved (ODI -16.8, PROMIS Pain -8.2; both p < 0.001), with significant reductions in kinesiophobia (TSK -7.1; p < 0.001). Lumbar decompression was associated with quantifiable improvements in postural stability and balance efficiency. High-resolution sway and CoE metrics provide objective, mechanistic biomarkers of functional recovery that complement traditional patient-reported outcomes. These findings support the potential role of dynamic balance assessment in postoperative evaluation and rehabilitation planning to reduce fall risk and optimize functional outcomes after lumbar spinal decompression.