The neutral zone is a region of intervertebral motion around the neutral posture where little resistance is offered by the passive spinal column. Several studies--in vitro cadaveric, in vivo animal, and mathematical simulations--have shown that the neutral zone is a parameter that correlates well with other parameters indicative of instability of the spinal system. It has been found to increase with injury, and possibly with degeneration, to decrease with muscle force increase across the spanned level, and also to decrease with instrumented spinal fixation. In most of these studies, the change in the neutral zone was found to be more sensitive than the change in the corresponding range of motion. The neutral zone appears to be a clinically important measure of spinal stability function. It may increase with injury to the spinal column or with weakness of the muscles, which in turn may result in spinal instability or a low-back problem. It may decrease, and may be brought within the physiological limits, by osteophyte formation, surgical fixation/fusion, and muscle strengthening. The spinal stabilizing system adjusts so that the neutral zone remains within certain physiological thresholds to avoid clinical instability.
"The neutral zone, defined as the region of minimal passive stiffness (Panjabi, 1992), has been used to standardize the test posture of functional spinal units (FSUs) for in vitro biomechanical studies (Balkovec & McGill, 2012; Callaghan & McGill, 2001; Gooyers, McMillan, Howarth, & Callaghan, 2012; "
"In the current work we study a novel conservative treatment performed primarily with active specialized manual therapy ( " hands on " ) named the POLD Concept (Pulsation Oscillation Long Duration) (L opez Díaz, 2005; L opez Díaz, 2012). This method is an evolution of rhythmic oscillating mobilization (Maitland, 2007) with the following differential aspects: (1) the oscillatory movement has a " sinusoidal " waveform, (2) resonant oscillation frequency is used between 1.2 and 2 Hz, (3) oscillation is maintained throughout treatment and is called primary oscillation, (4) very small amplitude (less than grade 1 according to Maitland) within the " neutral zone " (Panjabi, 1992) are used. "
[Show abstract][Hide abstract] ABSTRACT: This study analyses the efficacy of manual oscillatory therapy, following the POLD technique, for acute Lumbar Disc Hernia (LDH) and compares it to usual treatment. A randomised, controlled, triple-blind pilot clinical trial. The sample of 30 patients was divided into two homogeneous groups to receive usual treatment (A) or treatment with the POLD technique (B). We analysed range of motion and subjective variables such as the severity (visual analogue pain scale (VAS)) and extension of the pain. With the application of POLD therapy, patients presented significant changes on range of motion (forward flexion with p < 0.05) at completion of the trial in comparison with the control group. They showed a significant reduction in the severity of pain with a mean VAS scale for lumbar, glutaeus and thigh pain, which improved from 5.09 to 0.79, 5.07 to 0.97 and 4.43 to 0.49 respectively (p < 0.05), and also when compared to usual treatment (p < 0.05) for all body regions. Moreover, we observed a reduction in pain extension (centralization phenomena) (p < 0.001) in comparison with usual treatment.
"One possible explanation for increased EMG activity in subjects with LSI is that more muscle activation may be required to compensate for decreased passive stability in the lumbar region (De Groot et al., 2008; Arab et al., 2011). Panjabi (1992) theorized that dysfunction of the passive subsystem as a result of LSI is likely to be compensated for with enhanced muscle activation. The increase of muscle activity of the back and hip extensors in the LSI group may be explained by increased segmental movement due to disc degeneration (Li et al., 2011; Ibarz et al., 2013). "
[Show abstract][Hide abstract] ABSTRACT: The goal of the current study was to investigate potential differences in back and hip extensor muscle activity and hip extension force during prone hip extension (PHE) in individuals with lumbar segmental instability (LSI) and asymptomatic subjects. Thirty-six subjects with LSI and 26 asymptomatic volunteers participated in this study. Muscle activity of the erector spinae, gluteus maximus, and biceps femoris was recorded using electromyography (EMG), and hip extension force was measured by a digital force gauge. Muscle activity was significantly greater in subjects with LSI than in asymptomatic subjects during PHE (p < 0.05). Hip extension force was significantly lower in the subjects with LSI than in asymptomatic subjects during PHE (p < 0.05). These findings suggest that during PHE, subjects with LSI have differences in back and hip extensor muscle activity and hip extension force compared to asymptomatic individuals.
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