Spinal-pelvic sagittal parameters and plantar pressure characteristics in elderly patients with degenerative lumbar spondylolisthesis

Abstract

BACKGROUND: Degenerative lumbar spondylolisthesis is a common spinal degenerative disorder among older adults, often accompanied by spinopelvic sagittal imbalance. The characteristics of plantar pressure and balance function in these patients have not been fully elucidated. OBJECTIVE: To investigate the spinopelvic sagittal parameters and plantar pressure characteristics in older adults with degenerative lumbar spondylolisthesis, to provide a reference for early diagnosis and the development of rehabilitation plans in older adults with degenerative lumbar spondylolisthesis. METHODS: A total of 33 patients with degenerative lumbar spondylolisthesis (degenerative lumbar spondylolisthesis group) and 35 healthy older adults (control group) were enrolled. Lateral radiographs of the whole spine were obtained to measure spinopelvic sagittal parameters. Plantar pressure distribution, including the pressure ratio, peak pressure in eight regions of interest, and center of pressure trajectory parameters, was collected using a plantar pressure system. Differences in spinopelvic sagittal parameters, center of pressure trajectory, and plantar pressure parameters were compared between the two groups. RESULTS AND CONCLUSION: Compared with the control group, the degenerative lumbar spondylolisthesis group showed significantly increased pelvic incidence, pelvic tilt, sacral slope, and lumbar lordosis (P < 0.05). The pressure ratio of the left forefoot and forefoot was significantly increased (P < 0.05), while that of the left rearfoot and rearfoot was significantly decreased (P < 0.05). The peak pressure of the left first metatarsal was significantly increased (P < 0.05), while that of the right fifth metatarsal and left arch was significantly decreased (P < 0.05). Under both eyes-open and eyes-closed conditions, the center of pressure trajectory length, 95% confidence ellipse area, and average X/Y axis movement distance were significantly increased in the degenerative lumbar spondylolisthesis group (P < 0.05). These findings suggest that elderly patients with degenerative lumbar spondylolisthesis exhibit characteristic changes in spinopelvic sagittal parameters (increased pelvic incidence, pelvic tilt, sacral slope, and lumbar lordosis), a forward shift in plantar pressure distribution (increased forefoot pressure, decreased rearfoot pressure), and imbalance in foot mechanical symmetry and the 'triangular support structure'. These changes are accompanied by decreased center of pressure stability, reflecting impaired balance function.

1. Introduction

Degenerative lumbar spondylolisthesis is a common degenerative spinal disorder characterized by pathological intervertebral slippage, most frequently occurring at the L4-L5 segment [1]. In the Chinese elderly population, the prevalence of degenerative lumbar spondylolisthesis shows gender differences (19.1% in males, 25.0% in females), with males more prone to retrolisthesis [2]. Its pathogenesis is associated with degeneration of the disc-facet joint complex, developmental abnormalities, and spondylolysis [3-5]. Patients often present with mechanical low back pain, intermittent claudication, and radicular pain, due to reduced spinal canal volume caused by degeneration [6-7], leading to progressive motor dysfunction.

Biomechanical studies have revealed a close relationship between degenerative lumbar spondylolisthesis and spinopelvic sagittal imbalance. Mismatch between pelvic parameters such as pelvic incidence and lumbar lordosis is a core feature of sagittal imbalance [8], with pelvic tilt (mainly retroversion) serving as a key compensatory mechanism to maintain sagittal balance in decompensated states [9-10]. Notably, these spinopelvic changes transmit downward through the biomechanical chain, ultimately affecting the mechanical environment of the lower limbs and feet. This top-down mechanical alteration leads to abnormal load transfer to the foot and ankle, directly manifesting as characteristic changes in plantar pressure distribution. Recent studies have shown significant associations between spinopelvic sagittal imbalance and plantar pressure distribution, such as anterior displacement of the center of pressure and abnormal peak pressure distribution [11]. Kinematically, patients with degenerative lumbar spondylolisthesis often exhibit characteristic gait changes due to anterior displacement of the center of gravity, including reduced cadence, gait speed, and stride length [12]. These gait adjustments lead to remodeling of plantar pressure distribution, and long-term pressure changes may induce foot structural abnormalities, such as progressive arch collapse, hallux valgus, and flatfoot [13-14]. Furthermore, chronic plantar pressure changes can affect proprioceptive-neuromuscular control, further aggravating spinal alignment through postural compensation, forming a vicious cycle of sensorimotor integration impairment and increasing fall risk [15-16].

Plantar pressure systems can visually display the center of pressure trajectory, allowing direct observation of postural sway and movement in patients with degenerative lumbar spondylolisthesis, and can be used to analyze and evaluate balance function. However, the application of plantar pressure analysis to degenerative lumbar spondylolisthesis is still limited.