Relationships Between Joint Motion and Facet Joint Capsule Strain During Cat and Human Lumbar Spinal Motions

• Published in: Journal of manipulative and physiological therapeutics 2011-09, Vol.34 (7), p.420-431
• Main Authors: Ianuzzi, Allyson, PhD, Pickar, Joel G., DC, PhD, Khalsa, Partap S., DC, PhD
• Format: Article
• Language: English
• Subjects: Animals; Biomechanical Phenomena; Biomechanics; Cats; Facet Joint; Feline; Humans; In Vitro Techniques; Joint Capsule - physiology; Low Back Pain, Mechanical; Lumbar Vertebrae - innervation; Lumbar Vertebrae - physiology; Male; Mechanoreceptors - physiology; Movement - physiology; Physical Medicine and Rehabilitation; Proprioception; Range of Motion; Sensory Thresholds; Stress, Mechanical; Zygapophyseal Joint; Zygapophyseal Joint - physiology
• ISSN: 0161-4754; 1532-6586
• DOI: 10.1016/j.jmpt.2011.05.005

AbstractObjectiveThe lumbar facet joint capsule (FJC) is innervated with mechanically sensitive neurons and is thought to contribute to proprioception and pain. Biomechanical investigations of the FJC have commonly used human cadaveric spines, whereas combined biomechanical and neurophysiological studies have typically used nonhuman animal models. The purpose of this study was to develop mathematical relationships describing vertebral kinematics and FJC strain in cat and human lumbar spine specimens during physiological spinal motions to facilitate future efforts at understanding the mechanosensory role of the FJC. MethodsCat lumbar spine specimens were tested during extension, flexion, and lateral bending. Joint kinematics and FJC principal strain were measured optically. Facet joint capsule strain–intervertebral angle (IVA) regression relationships were established for the 3 most caudal lumbar joints using cat (current study) and human (prior study) data. The FJC strain–IVA relationships were used to estimate cat and human spine kinematics that corresponded to published sensory neuron response thresholds (5% and 10% strain) for low-threshold mechanoreceptors. ResultsSignificant linear relationships between IVA and strain were observed for both human and cat during motions that produced tension in the FJCs ( P < .01). During motions that produced tension in the FJCs, the models predicted that FJC strain magnitudes corresponding to published sensory neuron response thresholds would be produced by IVA magnitudes within the physiological range of lumbar motion. ConclusionsData from the current study support the proprioceptive role of lumbar spine FJC and low-threshold mechanoreceptive afferents and can be used in interpreting combined neurophysiological and biomechanical studies of cat lumbar spines.