Motion characteristics of the lumbar spinous processes with degenerative disc disease and degenerative spondylolisthesis

Abstract

Objective: Recently, interspinous process devices have attracted much attention since they can be implanted between the lumbar spinous processes (LSP) of patients with degenerative disc disease (DDD) and degenerative spondylolisthesis (DLS) using a minimally invasive manner. However, the motion characters of the LSP in the DLS and DDD patients have not been reported. This study is aimed at investigating the kinematics of the lumbar spinous processes in patients with DLS and DDD.

Methods: Ten patients with DDD at L4-S1 and ten patients with DLS at L4-L5 were studied. The positions of the vertebrae (L2-L5) at supine, standing, 45° trunk flexion, and maximal extension positions were determined using MRI-based models and dual fluoroscopic images. The shortest ISP distances were measured and compared with those of healthy subjects that have been previously reported.

Results: The shortest distance of the interspinous processes (ISP) gradually decreased from healthy subjects to DDD and to DLS patients when measured in the supine, standing, and extension positions. During supine-standing and flexion-extension activities, the changes in the shortest ISP distances in DDD patients were 2 ± 1.2 and 4.8 ± 2.1 mm at L4-L5; in DLS patients they were 0.5 ± 0.4 and 2.8 ± 1.7 mm at L4-L5, respectively. The range of motion is increased in DDD patients but decreased in DLS patients when compared with those of the healthy subjects. No significantly different changes were detected at L2-L3 and L3-L4 levels.

Conclusion: At the involved level, the hypermobility of the LSP was seen in DDD and hypomobility of the LSP in DLS patients. The data may be instrumental for improving ISP surgeries that are aimed at reducing post-operative complications such as bony fracture and device dislocations.

Fig. 1

a Digitized contours of lumbar vertebrae in the sagittal plane. b Three-dimensional anatomical vertebral model of L2–L5 from the magnetic resonance imaging

Fig. 2

a The experimental setup of the dual fluoroscopic imaging system for capturing the lumbar spine positions of living subjects. b Virtual reproduction of the DFIS and the vertebral positions

Fig. 3

Measurement of the shortest interspinous process using iterative closest point method

Fig. 4

Shortest interspinous process distance at various postures and different levels in a DDD, and b DLS patients. (*p < 0.05)

Fig. 5

Distance change between processes (a) during supine and standing and (b) during flexion and extension at different level. (*p < 0.05)