Surgical instrumentation for the in vivo determination of human lumbar spinal segment stiffness and viscoelasticity

A structured review of spinal stiffness as a kinesiological outcome of manipulation: Its measurement and utility in diagnosis, prognosis and treatment decision-making

“…The measurement methods were diverse and thus were categorised for comparison by separating them into those that measured stiffness via practitioner palpation and judgment (n = 13, Table 1) and those that used instrumentation (n = 62), and further subdividing instrumented measurement methods into three types. The instrumented studies were categorised into those that measured accessory movement at a particular spinal level (n = 42, Table 2), those that measured physiological movement of the spine with or without measurement of muscle activity (n = 13) (Brown et al, 2006;Brown and McGill, 2008Cholewicki et al, 1999Cholewicki et al, , 2000Drake et al, 2008;Essendrop et al, 2002;Gombatto et al, 2008a,b;Green et al, 2002;Hodges et al, 2009;Lee et al, 2006), and those that measured stiffness intraoperatively (n = 7) (Ambrosetti-Giudici et al, 2009;Brown et al, 2002a;Ebara et al, 1992;Hasegawa et al, 2008;Krenn et al, 2008;Nathan and Keller, 1994;Takano et al, 2006). Thirty-seven of these studies addressed factors that affect the instrumented measurement of spinal stiffness (Table 3), with 9 including participants with spinal pain and 28 including asymptomatic participants.…”

The effect of neighboring segments on the measurement of segmental stiffness in the intact lumbar spine

“…Recently, a number of different measurement devices have been developed with the aim of measuring segmental stiffness at a specific level [7][8][9][10][11][12][13]15,[20][21][22]. The present study showed that these methods can yield substantial overestimates, especially when adjacent segments have a high stiffness.…”

“…However, the assessment of segmental stiffness in vivo remains problematic. Although magnetic resonance imaging (MRI) and radiographs can visualize degeneration, and kinetic MRI and flexion-extension radiographs can show altered motion in degenerated segments [6][7][8], they do not provide information on segmental mechanical properties.…”

“…Efforts to make these assessments more objective and quantitative for research and future clinical applications have led to the development of intraoperative measurement devices. These devices typically consist of manually operated or motorized spinal spreaders and measure the force applied to the segment tested as well as its movement [7][8][9][10][11][12][13][14][15]. Segmental stiffness is then inferred from the relation between applied force and the resulting displacement.…”

Combining 3D tracking and surgical instrumentation to determine the stiffness of spinal motion segments: A validation study

“…Brown et al [6,7] and Hasegewa et al [8] developed motorized systems where distractor arms exhibit a translation along a rail. Krenn et al [9] recently modified a spinal spreader to measure force and displacement between the spinous processes, which was later further developed by Ambrosetti-Giudici et al [10]. All of the above mentioned setups performed a distraction between the spinous processes in the sagittal plane to induce a flexion and assumed a planar loading and motion.…”