Lumbar spinal stenosis and lower extremity motor control: the impact of walking-induced strain on a performance-based outcome measure

Objective: The primary objective of this study was to quantify the lower extremity movements and capabilities of a population with lumbar spinal stenosis (LSS) compared with healthy age-matched controls under conditions of strain and no strain. The secondary objective was to identify challenging movement conditions for a population with LSS, on a lower limb aiming task with different levels of difficulty, compared with healthy age-matched controls under conditions of strain and no strain.

Methods: Using a nonrandomized, controlled, before-and-after design, LSS patients (n = 16) and healthy controls (n = 16) performed 2 blocks of great toe-pointing movements to a series of projected squares. Following block 1, participants completed a 12-minute progressive exercise treadmill test. Pointing movements were analyzed using 3D motion analysis. Behavioral and kinematic measures evaluated performance.

Results: Both groups' reaction times (RTs) lengthened as task difficulty increased. An interaction revealed that LSS patients were more adversely impacted by task difficulty, F (3,372) = 4.207; P = .006. The progressive exercise treadmill test facilitated RT for both groups, F (1,124) = 5.105; P = .026. Control participants showed less variability in time-to-peak velocity poststrain, a benefit not shared by LSS patients, t (31) = 2.149; P = .040.

Conclusion: A lower extremity movement task captured differences under strain between healthy and LSS populations. The lower extremity Fitts' Law task accurately measured differences between healthy and LSS participants. For the subjects in this study, strain was sufficient to prevent LSS patients from demonstrating improvement in the variability of the ballistic phase of movement execution, whereas LSS patients' movement performance remained unchanged. This study also showed that regardless of strain, as task difficulty increased, LSS patients were more adversely impacted in the planning and execution of their lower limb movements than healthy control participants. The lower extremity motor control task (Fitts' task) can be used as a performance-based outcome measure to measure differences between healthy and LSS populations.