A. Claus

Different ways to balance the spine: Subtle changes in sagittal spinal curves affect regional muscle activity

Study Design. Exploratory study of regional muscle activity in different postures. Objective. To detail the relationship between spinal curves and regional muscle activity. Summary of Background Data. Sagittal balanced spinal posture (C7 above S1 in the sagittal plane) is a goal for spinal surgery and conservative ergonomics. Three combinations of thoracolumbar and lumbar spinal curves can be considered sagittal balanced postures: (i) flat—at both regions, (ii) long lordosis—lordotic at both regions, and (iii) short lordosis—thoracic kyphosis and lumbar lordosis. This study compares regional muscle activity between these 3 sagittal balanced postures in sitting, as well as a slump posture. Methods. Fine-wire electromyography (EMG) electrodes were inserted into the lumbar multifidus (deep and superficial), iliocostalis (lateral and medial), longissimus thoracis, and transversus abdominis in 14 healthy male volunteers. Fine-wire or surface EMG electrodes were also used to record activity of the obliquus internus, obliquus externus, and rectus abdominis muscles. Root mean square EMG amplitude in the flat, long lordosis, short lordosis, and slump sitting postures were normalized to maximal voluntary contraction, and also to the peak activity across the sitting postures. Muscle activity was compared between postures with a linear mixed model analysis. Results. Of the extensor muscles, it was most notable that activity of the deep and superficial fibers of lumbar multifidus increased incrementally in the 3 sagittal balanced postures; flat, long lordosis, and short lordosis (P < 0.05). Of the abdominal muscles, obliquus internus was more active in short lordosis than the other postures (P < 0.05). Comparing the sagittal balanced postures, the flat posture showed the least muscle activity (similar to the slump posture at most muscles examined). Conclusion. Discrete combinations of muscle activity supported the 3 different sagittal balanced postures in sitting, providing new detail for surgeons, researchers, and therapists to distinguish between different sagittal balanced postures.

Changes in Regional Activity of the Psoas Major and Quadratus Lumborum With Voluntary Trunk and Hip Tasks and Different Spinal Curvatures in Sitting

STUDY DESIGN Cross-sectional controlled laboratory study. OBJECTIVES To investigate the function of discrete regions of psoas major (PM) and quadratus lumborum (QL) with changes in spinal curvature and hip position. BACKGROUND Anatomically discrete regions of PM and QL may have differential function on the lumbar spine, based on anatomical and biomechanical differences in their moment arms between fascicles within each muscle. METHODS Fine-wire electrodes were inserted with ultrasound guidance into PM fascicles arising from the transverse process (PM-t) and vertebral body (PM-v) and anterior (QL-a) and posterior (QL-p) layers of QL. Recordings were made on 9 healthy participants, who performed 7 tasks with maximal voluntary efforts and adopted 3 sitting postures that involved different spinal curvatures and hip angles. RESULTS Activity of PM-t was greater during trunk extension than flexion, whereas activity of PM-v was greater during hip flexion than trunk efforts. Activity of QL-p was greater during trunk extension and lateral flexion, whereas QL-a showed greater activity during lateral flexion. During sitting tasks, PM-t was more active when sitting with a short lordosis than a flat (less extended) lumbar spine posture, whereas PM-v was similarly active in both sitting postures. CONCLUSION Activity of PM-t was more affected by changes in position of the lumbar spine than the hip, whereas PM-v was more actively involved in the movement of the hip rather than that of the lumbar spine. Moreover, from its anatomy, PM-t has a combined potential to extend/lordose the lumbar spine and flex the hip, at least in a flexed-hip position.

Can we predict the outcome for people with patellofemoral pain? A systematic review on prognostic factors and treatment effect modifiers

Background Patellofemoral pain (PFP) is a multifactorial and often persistent knee condition. One strategy to enhance patient outcomes is using clinically assessable patient characteristics to predict the outcome and match a specific treatment to an individual. Aim A systematic review was conducted to determine which baseline patient characteristics were (1) associated with patient outcome (prognosis); or (2) modified patient outcome from a specific treatment (treatment effect modifiers). Methods 6 electronic databases were searched (July 2016) for studies evaluating the association between those with PFP, their characteristics and outcome. All studies were appraised using the Epidemiological Appraisal Instrument. Studies that aimed to identify treatment effect modifiers underwent a checklist for methodological quality. Results The 24 included studies evaluated 180 participant characteristics. 12 studies investigated prognosis, and 12 studies investigated potential treatment effect modifiers. Important methodological limitations were identified. Some prognostic studies used a retrospective design. Studies aiming to identify treatment effect modifiers often analysed too many variables for the limiting sample size and typically failed to use a control or comparator treatment group. 16 factors were reported to be associated with a poor outcome, with longer duration of symptoms the most reported (>4 months). Preliminary evidence suggests increased midfoot mobility may predict those who have a successful outcome to foot orthoses. Conclusions Current evidence can identify those with increased risk of a poor outcome, but methodological limitations make it difficult to predict the outcome after one specific treatment compared with another. Adequately designed randomised trials are needed to identify treatment effect modifiers.

Recruitment of Discrete Regions of the Psoas Major and Quadratus Lumborum Muscles Is Changed in Specific Sitting Postures in Individuals With Recurrent Low Back Pain

STUDY DESIGN Cross-sectional controlled laboratory study. OBJECTIVES To investigate potential changes in the function of discrete regions of the psoas major (PM) and quadratus lumborum (QL) with changes in spinal curvatures and hip positions in sitting, in people with recurrent low back pain (LBP). BACKGROUND Although the PM and QL contribute to control of spinal curvature in sitting, whether activity of these muscles is changed in individuals with LBP is unknown. METHODS Ten volunteers with recurrent LBP (pain free at the time of testing) and 9 pain-free individuals in a comparison group participated. Participants with LBP were grouped into those with high and low erector spinae (ES) electromyographic (EMG) signal amplitude, recorded when sitting with a lumbar lordosis. Data were recorded as participants assumed 3 sitting postures. Fine-wire electrodes were inserted with ultrasound guidance into fascicles of the PM arising from the transverse process and vertebral body, and the anterior and posterior layers of the QL. RESULTS When data from those with recurrent LBP were analyzed as 1 group, PM and QL EMG signal amplitudes did not differ between groups in any of the sitting postures. However, when subgrouped, those with low ES EMG had greater EMG signal amplitude of the PM vertebral body and QL posterior layer in flat posture and greater EMG signal amplitude of the QL posterior layer in short lordotic posture, compared to those in the pain-free group. For the group with high ES EMG, the PM transverse process and PM vertebral body EMG was less than that of the other LBP group in short lordotic posture. CONCLUSION The findings suggest a redistribution of activity between muscles that have a potential extensor moment in individuals with LBP. The modification of EMG of discrete fascicles of the PM and QL was related to changes in ES EMG signal amplitude recorded in sitting.

Perspectives on Postural Control Dysfunction to Inform Future Research: A Delphi Study for Children With Cerebral Palsy

OBJECTIVE To identify whether consensus can be achieved in how clinicians and researchers define, describe, assess, and treat postural control dysfunction in children with cerebral palsy (CP). DESIGN Delphi study with 3 iterative rounds. SETTING Electronic survey. PARTICIPANTS Researchers and/or clinicians (N=43) from 7 countries with a mean ± SD of 20±11 years of experience working with children with CP participated. Participants included authors of published works on postural control in CP (identified from a recent systematic review), members of the Australasian Academy of CP and Developmental Medicine, and 2 major Australian rehabilitation providers. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES The Delphi study consisted of 3 iterative rounds of surveys. In Round 1, respondents answered open-ended questions regarding their views on (1) definition items for postural control, (2) theoretical frameworks, (3) methods for assessment, and (4) interventions for postural control dysfunction in children with CP. Rounds 2 and 3 were made up of items generated by participants in Round 1 and combined with items identified from the literature. Participants indicated their level of agreement for each item on a 7-point Likert scale. Threshold for consensus was ≥85% agreement. RESULTS Of 306 items generated, 174 reached consensus by Round 3. Most postural control definition items (90%) achieved consensus. Two theoretical frameworks (14%) reached consensus. Less than half (42%) of assessment items reached consensus. More individual assessment items (89%) reached consensus than multi-item tools (4%). Just over half (61%) of the items generated for interventions reached consensus. CONCLUSION Consensus was achieved for a postural control definition. However, substantial research is needed to establish a comprehensive, postural control-specific framework and suite of assessments. These would provide a foundation to improve intervention selection and dosage.

Manual handling: differences in perceived effort, success rate and kinematics between three different pushing techniques

This study examined the perceived effort, success rates and kinematics for three push strategies in a simulated lateral patient transfer (horizontal slide). Thirteen healthy subjects (four males) completed three repetition pushing loads of 6, 10 and 14 kg in random order; with a spontaneous push strategy, then with a straight-back bent-knees (squat) strategy and the preparatory pelvic movement (‘rockback’) strategy in random order. Perceived effort and kinematic parameters measured at the onset of movement and at maximum push excursion were compared between strategies and between loads with repeated measures ANOVA. The spontaneous and ‘rockback’ strategies achieved the pushing task with less perceived effort across all loads than the squat push (P < 0.001). Only 3/13 participants were successful on all attempts at pushing the 14 kg load using a squat strategy, which contrasted with 12/13 participants when the spontaneous strategy or the ‘rockback’ strategy was used. Forward movement of the pelvis and forward trunk inclination may be positively associated with lower perceived effort in the push task. Practitioner Summary: In a manual-handling task that simulated a lateral patient transfer (horizontal slide), perceived effort and success rates of three push strategies were compared. A straight-back bent-knees push (squat) strategy demonstrated greater perceived effort and lower success rates than a spontaneous push strategy, or a push strategy with preparatory ‘rockback’ pelvic movement.

Different ways to balance the spine in sitting: Muscle activity in specific postures differs between individuals with and without a history of back pain in sitting

Background: Previous research explored muscle activity in four distinct sitting postures with fine‐wire electromyography, and found that lumbar multifidus muscle activity increased incrementally between sitting with flat thoracolumbar and lumbar regions, long thoracolumbar lordosis, or short lordosis confined to the lumbar region. This study used similar methods to explore whether people with a history of low back pain provoked by prolonged sitting used different patterns of trunk muscle activity in specific postures. Methods: Fine‐wire electromyography electrodes were inserted into the right lumbar multifidus (deep and superficial), iliocostalis (lateral and medial), longissimus thoracis and transversus abdominis muscles. Superficial abdominal muscle activity was recorded with surface or fine‐wire electrodes. Electromyography amplitude was compared between postures for the back pain group and observations were contrasted with the changes previously reported for pain‐free controls. For comparison between groups normalised and non‐normalised electromyography amplitudes were compared. Findings: Individuals with a history of back pain demonstrated greater activity of the longissimus thoracis muscle in the long lordosis compared with the flat posture [mean difference (95% CI): 46.6 (17.5–75.7)%, normalised to sitting posture peak activity], but pain‐free participants did not [mean difference: 7.7 (minus 12–27.6)%]. Pain‐free participants modulated lumbar multifidus activity with changes in lumbar curve, but people with a history of pain in prolonged sitting did not change multifidus activity between the long and short lordotic postures. Interpretation: In clinical ergonomic interventions that modify spinal curves and sagittal balance in sitting, the muscle activity used in those postures may differ between people with and without a history of back pain.

Reproducibility of the Balance Evaluation Systems Test (BESTest) and the Mini-BESTest in school-aged children

This study evaluated the intra-rater, inter-rater and test-retest reproducibility of the Full-BESTest and Mini-BESTest when assessing postural control in children. Thirty-four children aged 7-17 years participated in intra-rater and inter-rater evaluation, and 22 children repeated assessment six weeks later for evaluation of test-retest reliability. Postural control was assessed using the Full Balance Evaluation Systems Test (Full-BESTest) and the short-form Mini-BESTest. Intra-rater, inter-rater and test-retest reproducibility were examined using video assessment. Test-retest reproducibility was also assessed in real-time. Reproducibility was examined by agreement and reliability statistics. Agreement was calculated using percentage of agreement, Limits of Agreement and Smallest Detectable Change. Reliability was calculated using Intra-class Correlation Coefficients. Results showed that the reliability of Total Scores was excellent for the Full-BESTest for all conditions (all ICCs>0.82), whereas the Mini-BESTest ranged from fair to excellent (ICC=0.56-0.86). Percentage of Domain Scores with good-excellent reliability (ICCs>0.60) was slightly higher for the Full-BESTest (66%) compared to the Mini-BESTest (59%). Smallest Detectable Change scores were good to excellent for the Full-BESTest (2%-6%) and for the Mini-BESTest (5%-10%) relative to total test scores. Both the Full-BESTest and Mini-BESTest can discriminate postural control abilities within and between days in school-aged children. The Full-BESTest has slightly better reproducibility and a broader range of items, which could be the most useful version for treatment planning. We propose minor modifications to improve reproducibility for children, and indicate the modified version by the title Kids-BESTest. Future psychometric research is recommended for specific paediatric clinical populations.

A new method for sudden mechanical perturbation with axial load, to assess postural control in sitting and standing

Sudden application of load along a sagittal or coronal axis has been used to study trunk stiffness, but not axial (vertical) load. This study introduces a new method for sudden-release axial load perturbation. Prima facie validity was supported by comparison with standard mechanical systems. We report the response of the human body to axial perturbation in sitting and standing and within-day repeatability of measures. Load of 20% of body weight was released from light contact onto the shoulders of 22 healthy participants (10 males). Force input was measured via force transducers at shoulders, output via a force plate below the participant, and kinematics via 3-D motion capture. System identification was used to fit data from the time of load release to time of peak load-displacement, fitting with a 2nd-order mass-spring-damper system with a delay term. At peak load-displacement, the mean (SD) effective stiffness measured with this device for participants in sitting was 12.0(3.4)N/mm, and in standing was 13.3(4.2)N/mm. Peak force output exceeded input by 44.8 (10.0)% in sitting and by 30.4(7.9)% in standing. Intra-class correlation coefficients for within-day repeatability of axial stiffness were 0.58 (CI: -0.03 to 0.83) in sitting and 0.82(0.57-0.93) in standing. Despite greater degrees of freedom in standing than sitting, standing involved lesser time, downward displacement, peak output force and was more repeatable in defending upright postural control against the same axial loads. This method provides a foundation for future studies of neuromuscular control with axial perturbation.

Two examples of 'cuboid syndrome' with active bone pathology: Why did manual therapy help?

Cuboid syndrome describes lateral midfoot pain localised to the cuboid bone. Previously reported case studies promoted joint mobilisation or manipulation interventions. The assumed mechanism was correction of a subtle disruption to the calcaneocuboid joint position. There is an absence of evidence for correction of joint position, but there is evidence of neurophysiological mechanisms for pain modulation. This case study reports on a patient who suffered two occurrences of cuboid syndrome on opposite feet, three years apart. With both occurrences, joint mobilisation achieved rapid and lasting resolution of severe pain and functional limitations. This occurred despite the presence of an active bone pathology at the symptomatic cuboid (demonstrated with nuclear imaging), which could represent a stress reaction, transient osteoporosis, ischaemic necrosis, infection or neoplasm. This case contributes three considerations for clinical reasoning and manual therapy research. 1. Active local bone pathology could exist in other patients with pain at the cuboid, and other conditions where symptoms resolve with joint mobilisation. 2. Rapid and lasting symptom resolution fits with a hypothesis that joint mobilisation acted to reverse neurological sensitisation. 3. Lasting symptom resolution may be clinically associated with manual therapy, but mechanisms extending beyond temporary analgesia are yet to be identified.