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Table 2 Posturography

From: Altered postural timing and abnormally low use of proprioception in lumbar spinal stenosis pre- and post- surgical decompression

  Patients
N = 11
Patients post-surgery
N = 9
Control subjects
N = 15
P
Mean (SE) Δ (%) Mean (SE)
Spontaneous sway
 RMS (cm) 0.56 (0.02)   0.43 (0.01) < 0.000*
  −5.3   0.029*
 MV (cm/sec) 0.72 (0.04)   0.52 (0.03) 0.002*
  −6.4   0.244
 CF (Hz) 0.50 (0.50)   0.44 (0.01) 0.001*
  4.6   0.071
Perturbed stance
 Mean GAIN 1.85 (0.02)   1.93 (0.02) 0.015*
  1.2   0.482
 Mean PHASE (°) −98.83 (2.22)   −119.09 (1.90) < 0.000*
  15.3   < 0.000*
Model parameters
 Ki (s −1·rad− 1) 74.95 (2.63)   74.85 (2.25) 0.979
  5.2   0.407
 Kp (rad−1) 1093.64 (39.11)   1047.63 (33.49) 0.374
  0.0   0.994
 Kd (s·rad−1) 307.39 (8.61)   285.62 (7.37) 0.058
  −4.3   0.206
 Wp (%) 61.04 (2.59)   68.81 (2.22) 0.025*
  3.1   0.595
 Td (msec) 172 (6.1)   172 (5.3) 0.919
  −5.0   0.344
 Ppas (rad−1) 82.25 (3.37)   82.88 (2.88) 0.888
  −9.0   0.490
 Dpas (s·rad−1) 55.93 (1.42)   57.09 (1.21) 0.533
  6.3   0.296
  1. *indicates a significant difference p < 0.05
  2. Δ post-surgery minus pre-surgery, SE standard error, RMS root means square, MV mean velocity, CF center frequency, Ki integral gain of the Neural Controller, Kp proportional gain (stiffness factor), Kd derivative gain (damping factor), Wp proprioceptive sensory weight, Td feedback time delay, Ppas passive stiffness factor, Dpas passive damping factor