The Stabilizing System of the Spine. Part I. Function, Dysfunction, Adaptation, and Enhancement

Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, Connecticut 06510.
Journal of Spinal Disorders (Impact Factor: 1.21). 01/1993; 5(4):383-9; discussion 397. DOI: 10.1097/00002517-199212000-00001
Source: PubMed


Presented here is the conceptual basis for the assertion that the spinal stabilizing system consists of three subsystems. The vertebrae, discs, and ligaments constitute the passive subsystem. All muscles and tendons surrounding the spinal column that can apply forces to the spinal column constitute the active subsystem. The nerves and central nervous system comprise the neural subsystem, which determines the requirements for spinal stability by monitoring the various transducer signals, and directs the active subsystem to provide the needed stability. A dysfunction of a component of any one of the subsystems may lead to one or more of the following three possibilities: (a) an immediate response from other subsystems to successfully compensate, (b) a long-term adaptation response of one or more subsystems, and (c) an injury to one or more components of any subsystem. It is conceptualized that the first response results in normal function, the second results in normal function but with an altered spinal stabilizing system, and the third leads to overall system dysfunction, producing, for example, low back pain. In situations where additional loads or complex postures are anticipated, the neural control unit may alter the muscle recruitment strategy, with the temporary goal of enhancing the spine stability beyond the normal requirements.

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    • "Adequate neuromuscular control of the lumbar spine is required to provide adequate mechanical stability and most likely prevent lumbar injury (Panjabi, 1992; 2006). Measuring unstable sitting balance, as a surrogate measure of trunk postural control, can be considered as a challenging " functional " test. "
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    ABSTRACT: Adequate neuromuscular control of the lumbar spine is required to prevent lumbar injuries. A trunk postural control test protocol, controlling for the influence of body size on performance, was implemented to carry out between-subject comparisons. The aim of this study was to assess the effect of sex and low back pain status with the use of two measures of trunk postural control, the first based on chair motion, and the second based on trunk motion. Thirty-six subjects (with and without low back pain) performed three 60-s trunk postural control trials with their eyes closed while seated on an instrumented wobble chair, following a calibration procedure. Chair and trunk angular kinematics were measured with an optoelectronic system. A chair-based stabilogram and a trunk-based (lumbar spine) stabilogram were created using the angular motions produced in the sagittal and frontal planes. Twenty body-sway measures were computed for each stabilogram. The calibration task efficiently controlled for the influence of body size. Several sex effects were detected, with most of them originating from the trunk-based measures. Subjects with low back pain and healthy controls showed comparable trunk postural control. Sex differences were substantiated for the first time, but almost only with the trunk-based stabilogram, showing that the kinematic information captured on the trunk segments is quite different from what is captured on the wobble chair. Contrary to previous studies, pain status was not related to lowered trunk postural control, which can be attributed to the patients recruited or measurement reliability issues. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Clinical biomechanics (Bristol, Avon) 07/2015; DOI:10.1016/j.clinbiomech.2015.07.006 · 1.97 Impact Factor
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    • "Thus, voluntary and postural strategies appear to undergo different task-specific adaptations in the presence of real or anticipated noxious input. Although augmented muscle activity might be necessary to compensate for reduced mechanical support afforded by injured joint structures (Panjabi 1992), replication of changes in motor control with experimental nociceptive stimulation (i.e. in the absence of injury) (Arendt-Nielsen et al. 1996) and when pain is anticipated (Moseley et al. 2004) indicates that injury to joint structures is not necessary to induce change in motor behaviour. This supports the notion that modified motor behaviour is mediated by supraspinal mechanisms. "
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    ABSTRACT: This study tested two contrasting theories of adaptation of postural control to pain. One proposes alteration to the postural strategy including inhibition of muscles that produce painful movement; another proposes amplification of the postural adjustment to recruit strategies normally reserved for higher load. This study that aimed to determine which of these alternatives best explains pain-related adaptation of the hip muscle activity associated with stepping down from steps of increasing height adaptation of postural control to increasing load was evaluated from hip muscle electromyography (fine-wire and surface electrodes) as ten males stepped from steps of increasing height (i.e. increasing load). In one set of trials, participants stepped from a low step (5 cm) and pain was induced by noxious electrical stimulation over the sacrum triggered from foot contact with a force plate or was anticipated. Changes in EMG amplitude and onset timing were compared between conditions. Hip muscle activation was earlier and larger when stepping from higher steps. Although ground reaction forces (one of the determinants of joint load) were unchanged before, during and after pain, trials with real or anticipated noxious stimulation were accompanied by muscle activity indistinguishable from that normally reserved for higher steps (EMG amplitude increased from 9 to 17 % of peak). These data support the notion that muscle activation for postural control is augmented when challenged by real/anticipated noxious stimulation. Muscle activation was earlier and greater than that required for the task and is likely to create unnecessary joint loading. This could have long-term consequences if maintained.
    Experimental Brain Research 06/2015; 233(9). DOI:10.1007/s00221-015-4347-0 · 2.04 Impact Factor
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    • "If a swimmer's lumbar alignment during underwater streamline position can be investigated, it may be possible to evaluate whether the swimmer has a hyperextension position or not. On the other hand, trunk muscle activity is considered to be an important factor to control lumbar alignment (Panjabi, 1992), therefore, trunk muscle activity may influence the control of lumbar alignment during streamline position. Previous study indicated that to control spinal stability and to strengthen trunk muscle is important for competitive swimmers in order to prevent lumbar disorders (Kenal & Knapp, 1996). "
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    ABSTRACT: We investigated the relationship between lumbar alignment and trunk muscle activities during the underwater streamline position. Twenty‐two male collegiate swimmers participated in the study. Firstly, spinal alignments of 22 participants were evaluated during standing and underwater streamline position using image analysis. Thoracic kyphosis angle and lumbar lordosis angle were measured to evaluate the spinal alignment. Secondly, eleven swimmers participated to the continued investigation: 6 participants who had the smallest alteration in lumbar lordosis between the two positions (these became the smallest group) and 5 participants who had the largest alteration (these became the largest group). Their spinal alignments and their trunk muscles activities were measured during two positions in the same manner as was performed in the first experiment. The muscles activities were measured using surface electromyography. As a result, a significant difference between the two groups was observed in the internal oblique/transversus abdominis muscle activities during the underwater streamline position (p<0.05). Therefore, it was considered that the internal oblique/transversus abdominis muscle activities were related to the magnitude of the lumbar lordosis alteration during the underwater streamline position.
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