Non-specific chronic low back pain: differences in spinal kinematics in subgroups during functional tasks
Hemming, R., Sheeran, L., van Deursen, R. et al. Eur Spine J (2018) 27: 163.
https://doi.org/10.1007/s00586-017-5217-1
Abstract
Purpose
A multidimensional classification approach suggests that motor control impairment subgroups exist in non-specific chronic low back pain (NSCLBP). Differences in sitting lumbar posture have been identified between two such subgroups [flexion pattern (FP) and active extension pattern (AEP)] and healthy individuals; however, functional spinal movement has not been explored. This study will evaluate whether NSCLBP subgroups exhibit regional spinal kinematic differences, compared to healthy individuals, during functional tasks.
Methods
Observational, cross-sectional study design. Spinal kinematics of 50 NSCLBP subjects (27 FP, 23 AEP) and 28 healthy individuals were investigated using 3D motion analysis (Vicon™) during functional tasks [reaching upwards, step down, step up, lifting, and replacing a box, stand-to-sit, sit-to-stand, bending to retrieve (and returning from retrieving) a pen from the floor]. Mean sagittal angle for the total thoracic, total lumbar, upper thoracic, lower thoracic, upper lumbar, and lower lumbar regions between groups was compared.
Results
Significant differences were observed in lower thoracic and upper lumbar regions between NSCLBP subgroups during most tasks. Significant differences were observed between the FP and healthy group in the lower thoracic region during stand-to-sit-to-stand tasks and bending (and returning from) to retrieve a pen from the floor. All significant results demonstrated the FP group to operate in comparatively greater flexion.
Conclusions
The thoraco-lumbar spine discriminated between FP and AEP, and FP and healthy groups during functional tasks. FP individuals demonstrated more kyphotic thoraco-lumbar postures, which may be pain provocative. No significant differences were observed between AEP and healthy groups, suggesting that alternative mechanisms may occur in AEP.
Keywords
Non-specific chronic low back pain Functional movement Kinematics Lumbar Thoracic
Introduction
Non-specific chronic low back pain (NSCLBP) is a complex heterogeneous biopsychosocial disorder with multiple manifestations [1]. Despite considerable NSCLBP research, there is little reported change in long-term prognosis [2] with intervention outcomes reported to be short term and moderate at best [3]. Difficulties in establishing effective interventions are likely to be due to an inability to define clear homogeneous NSCLBP subgroups; therefore, identifying specific NSCLBP subgroups using validated subclassification approaches is paramount [4].
For some NSCLBP individuals, the main driver for pain may be movement and posture behaviour indicating a mechanical basis for the disorder. A multidimensional classification system (MDCS), which considers such mechanisms, for example, maladaptive motor control impairment (MCI) (characterised by pain provocative behaviours), has been proposed [5].
This MDCS [5] outlines five NSCLBP MCI subgroups, where individuals are proposed to display full range of movement (ROM) in the direction of pain provocation and are clinically observed to habitually adopt end-range postures. These MCI subgroups are based upon subjective reporting of direction-specific aggravating and easing factors (described elsewhere [6]). MCI patients have been shown to display high levels of fear avoidance to adopt maladaptive end-range postures and movement strategies that may promote increased pain [6, 7, 8]. Treatment for these individuals focuses on reducing fear avoidance and optimising spinal control during functional activity to avoid end-range repetitive strain, reduce spinal loading, and subsequently reduce peripheral nociceptor sensitivity [5]. Previous work has established distinct physical characteristics between two proposed MCI subgroups (Active Extension Pattern and Flexion Pattern) and healthy individuals in adolescent and adult populations, with alterations in spinal position sense, spinal kinematics and trunk muscle activity observed during static postures [7, 8, 9, 10].
Interventions focussed on targeted intervention for these MCI subgroups, such as Classification-based cognitive functional therapy (CB-CFT), have also been proposed to be effective when compared with usual care [11]. Despite CB-CFT incorporating functional re-education approaches, to date, no published work has evaluated how NSCLBP MCI subgroups operate during dynamic functional activities.
The purpose of this study is to better understand differences in spinal kinematics between NSCLBP subgroups and healthy individuals during functional tasks. This knowledge may assist in informing specific movement re-education in CB-CFT and aid development of novel sensor and biofeedback technologies to promote back pain self-management.
The hypothesis for this observational, cross-sectional study is that a difference in regional sagittal spinal curvatures between NSCLBP subgroups and healthy controls will be observed during a series of functional tasks.
Materials and methods
NSCLBP patients were recruited from routine physiotherapy waiting lists in Cardiff and Vale University Health Board (Cardiff, UK). Fifty NSCLBP and 28 healthy individuals volunteered. Ethical approval was obtained from The Research Ethics Committee 3 Wales (10/MRE09/28) within the Arthritis Research UK Biomechanics and Bioengineering Centre, Cardiff University. Informed consent was obtained from all participants. Sample size was based on lower lumbar sagittal spinal angle, which has been shown to discriminate between AEP and FP subgroups in sitting [7]. Power set at priori at 0.7, alpha level of 0.05, a sample of 24 subjects per group was calculated.
Inclusion and exclusion criteria for the non-specific chronic low back pain (NSCLBP) group
Inclusion criteria for the NSCLBP group |
Exclusion criteria for the NSCLBP group |
---|---|
Aged 18–65 years History of chronic LBP (>12 weeks) Pain in the lumbar and/or buttock region (defined as pain reported below the level of T12 and no lower than the buttock line) Clear mechanical basis of the disorder aligned with specific aggravating and easing postures and movements, with distinct symptom relief observed during movement conducted in the opposing direction of reported pain provocation (assessed subjectively and objectively) Clinical diagnosis of specific MCI—either FP or AEP |
Signs of serious spinal pathology (red flags) including significant trauma, unexplained weight loss and widespread neurologic changes Any vestibular, visual or neurological dysfunction affecting balance Current radiating symptoms (and/or neurological deficit) below the level of the buttock crease Current pregnancy or breastfeeding History of spinal surgery, fracture or malignancy Inability to perform any of the functional tasks unaided Inability to read written English language documents and follow verbal instructions in English Not fulfilling the inclusion criteria |
Data collection
Custom-designed marker set a anterior view and b posterior view
Labelled marker set as visualised in Vicon®
Data processing and analysis
Sub-division of spinal curvature
Statistical analysis
Statistical tests were performed based on the normal distribution and homogeneity of variance [18]. Differences in baseline characteristics between groups were determined using: one-way ANOVA with post-hoc comparisons (Bonferroni) for age and height; independent samples Kruskal–Wallis for mass and BMI, χ 2 for gender; independent t tests for ODQ, VAS, and TSK; and Mann–Whitney U for DRAM. Following a repeated measures ANOVA for overall group effect, one-way ANOVAs with post-hoc Bonferroni testing determined between group kinematic differences. All statistical testing was performed in SPSS (version 20.0, IBM Corp, Armonk, NY, USA). The alpha level was set at 0.05 [18, 19].
Results
Subject baseline characteristics across groups
Variable |
AEP (n = 23) |
FP (n = 27) |
Healthy (n = 28) |
Significance |
---|---|---|---|---|
Subject demographics |
||||
Gender |
||||
Males |
4 (17.4%) |
21 (77.8%) |
12 (42.9%) |
p < 0.001* |
Females |
19 (82.6%) |
6 (22.2%) |
16 (57.1%) |
|
Age (years) |
43.7 (11.2) |
41.0 (10.0) |
38.5 (11.2) |
p = 0.238 |
Mass (kg) |
68.9 (18.0) |
82.5 (14.6) |
72.9 (15.2) |
p = 0.005* (AEP vs. FP) |
Height (cm) |
164.9 (10.2) |
175.9 (8.7) |
169.4 (7.3) |
p < 0.001* (AEP vs. FP/FP vs. H) |
BMI (kg/m2) |
20.8 (4.9) |
23.4 (3.5) |
21.5 (4.1) |
p = 0.127 |
Pain |
||||
Site of back pain, n (%) |
||||
Right |
8 (34.8%) |
5 (18.5%) |
– |
– |
Left |
2 (8.7%) |
3 (11.1%) |
||
Central |
13 (56.4%) |
19 (70.4%) |
||
Time since pain onset, n (%) |
||||
3–6 months |
2 (8.7%) |
8 (29.6%) |
– |
– |
6–12 months |
7 (30.4%) |
2 (7.4%) |
– |
– |
1–2 years |
1 (4.3%) |
3 (11.1%) |
– |
– |
2–3 years |
0 (0%) |
1 (3.7%) |
– |
– |
3–4 years |
2 (8.7%) |
2 (7.4%) |
– |
– |
4–5 years |
3 (13%) |
3 (11.1%) |
– |
– |
5–10 years |
3 (13%) |
4 (14.8%) |
– |
– |
10+ years |
5 (21.7%) |
4 (14.8%) |
– |
– |
AEP (n = 23) |
FP (n = 26) |
Healthy (n = 28) |
Significance |
|
---|---|---|---|---|
Patient reported measures |
||||
ODQ |
22.5 (11.6) |
21.6 (10.0) |
– |
p = 0.773 |
DRAM |
29.8 (12.5) |
22.7 (10.9) |
– |
p = 0.027* |
VAS |
4.6 (1.4) |
4.5 (1.4) |
– |
p = 0.986 |
TSK |
37.5 (6.8) |
37.6 (5.3) |
– |
p = 0.993 |
Reliability
Test re-test reliability was established in a sub-sample of ten healthy volunteers (5 male, 5 female) across four consecutive trials of each functional task. Intraclass correlation coefficients (ICC) were calculated using a two-way mixed model (single measures) with consistency and demonstrated substantial to excellent reliability (ICC 0.746–0.977) across all spinal regions and tasks [20].
Patient reported measures
Independent t tests for ODQ, VAS, and TSK revealed no significant between differences between the AEP and FP groups indicating comparable baseline levels of disability, pain, and fear of movement between groups. A Mann–Whitney U test revealed the AEP group to display a significantly more distressed profile compared to the FP group (p = 0.027).
Spinal kinematics in the FP, AEP, and healthy groups
Descriptive and inferential results (one-way ANOVA and post-hoc Bonferroni) for the mid-point sagittal thoracic spinal curvatures for each functional task between the active extension pattern, flexion pattern, and healthy groups
Task |
Classification group descriptives (°) |
One-way ANOVA |
Post-hoc Bonferroni (p < 0.05) |
|||
---|---|---|---|---|---|---|
Mean (SD) |
||||||
AEP (n = 23) |
FP (n = 27) |
Healthy (n = 28) |
F |
p |
||
Upper thoracic |
||||||
Reach up |
27.2 (8.2) |
25.3 (7.8) |
27.1 (7.6) |
0.485 |
0.618 |
– |
Step down |
34.5 (8.2) |
33.8 (7.9) |
35.2 (6.9) |
0.206 |
0.815 |
– |
Step up |
33.1 (7.5) |
32.1 (7.4) |
34.1 (6.9) |
0.521 |
0.596 |
– |
Box replace |
26.8 (8.5) |
25.4 (7.2) |
26.6 (7.7) |
0.238 |
0.789 |
– |
Box lift |
23.3 (9.9) |
23.9 (7.1) |
24.0 (8.5) |
0.049 |
0.952 |
– |
Stand-to-sit |
22.1 (8.8) |
20.5 (6.7) |
22.5 (7.8) |
0.48 |
0.621 |
– |
Sit-to-stand |
20.4 (8.7) |
18.8 (6.2) |
20.6 (7.4) |
0.454 |
0.637 |
– |
Pick up pen (bend down) |
17.2 (10.5) |
19.2 (9.0) |
18.8 (8.2) |
0.296 |
0.745 |
– |
Pick up pen (return) |
14.3 (11.5) |
15.1 (8.5) |
15.6 (9.1) |
0.099 |
0.905 |
– |
Lower thoracic |
||||||
Reach up |
4.4 (13.1) |
11.1 (9.2) |
6.4 (11.4) |
2.344 |
0.103 |
– |
Step down |
9.5 (13.2) |
18.4 (9.1) |
12.6 (10.3) |
4.353 |
0.016* |
AEP vs. FP |
Step up |
10.0 (12.5) |
18.0 (9.2) |
11.8 (10.3) |
3.967 |
0.023* |
AEP vs. FP |
Box replace |
13.0 (10.0) |
21.7 (8.2) |
15.5 (11.0) |
5.231 |
0.007* |
AEP vs. FP |
Box lift |
14.1 (9.8) |
22.4 (7.9) |
16.7 (10.2) |
5.144 |
0.008* |
AEP vs. FP |
Stand-to-sit |
8.8 (11.2) |
18.1 (8.5) |
10.7 (10.9) |
5.997 |
0.004* |
AEP vs. FP/FP vs. H |
Sit-to-stand |
7.8 (11.0) |
17.6 (8.1) |
9.9 (11.2) |
6.638 |
0.002* |
AEP vs. FP/FP vs. H |
Pick up pen (bend down) |
20.4 (9.9) |
26.4 (6.6) |
20.4 (7.4) |
5.027 |
0.009* |
AEP vs. FP/FP vs. H |
Pick up pen (return) |
19.0 (8.7) |
25.0 (6.1) |
19.3 (7.6) |
5.478 |
0.006* |
AEP vs. FP/FP vs. H |
Descriptive and inferential results (one-way ANOVA and post-hoc Bonferroni) for the mid-point sagittal lumbar spinal curvatures for each functional task between the active extension pattern, flexion pattern, and healthy groups
Task |
Classification group descriptives (°) |
One-way ANOVA |
Post-hoc Bonferroni (p < 0.05) |
|||
---|---|---|---|---|---|---|
Mean (SD) |
||||||
AEP (n = 23) |
FP (n = 27) |
Healthy (n = 28) |
F |
p |
||
Upper lumbar |
||||||
Reach up |
−19.2 (12.0) |
−11.0 (10.0) |
−17.4 (8.0) |
4.824 |
0.011* |
AEP vs. FP |
Step down |
−18.0 (11.8) |
−8.1 (9.5) |
−15.1 (8.4) |
6.902 |
0.002* |
AEP vs. FP/FP vs. H |
Step up |
−17.0 (11.2) |
−7.3 (8.9) |
−14.1 (7.8) |
7.432 |
0.001* |
AEP vs. FP/FP vs. H |
Box replace |
−13.8 (10.9) |
−3.8 (8.6) |
−10.1 (7.4) |
7.844 |
0.001* |
AEP vs. FP/FP vs. H |
Box lift |
−11.6 (9.4) |
−2.4 (9.4) |
−7.5 (7.5) |
6.849 |
0.002* |
AEP vs. FP |
Stand-to-sit |
−11.9 (9.7) |
−0.8 (8.5) |
−6.3 (7.3) |
10.53 |
<0.001* |
AEP vs. FP |
Sit-to-stand |
−10.6 (8.7) |
−0.6 (8.3) |
−5.4 (7.6) |
9.05 |
<0.001* |
AEP vs. FP |
Pick up pen (bend down) |
−1.6 (7.0) |
4.3 (6.3) |
0.1 (5.3) |
5.83 |
0.005* |
AEP vs. FP/FP vs. H |
Pick up pen (return) |
−1.9 (7.3) |
3.9 (6.2) |
1.1 (5.4) |
4.978 |
0.009* |
AEP vs. FP |
Lower lumbar |
||||||
Reach up |
−23.3 (19.8) |
−29.9 (18.5) |
−22.6 (13.9) |
1.426 |
0.247 |
– |
Step down |
−21.1 (20.8) |
−23.7 (16.1) |
−20.2 (9.9) |
0.341 |
0.712 |
– |
Step up |
−19.0 (19.6) |
−22.8 (15.7) |
−17.4 (9.9) |
0.922 |
0.402 |
– |
Box replace |
−20.5 (17.3) |
−24.7 (13.5) |
−18.9 (10.1) |
1.258 |
0.29 |
– |
Box lift |
−14.8 (16.7) |
−20.4 (13.7) |
−15.0 (9.7) |
1.426 |
0.247 |
– |
Stand-to-sit |
−11.6 (15.0) |
−12.0 (11.6) |
−9.7 (9.4) |
0.292 |
0.748 |
– |
Sit-to-stand |
−11.0 (15.8) |
−11.3 (12.0) |
−9.0 (8.9) |
0.283 |
0.755 |
– |
Pick up pen (bend down) |
−5.2 (16.3) |
−5.4 (11.9) |
−2.2 (10.3) |
0.506 |
0.605 |
– |
Pick up pen (return) |
−5.3 (15.2) |
−4.8 (13.1) |
−2.5 (10.0) |
0.36 |
0.699 |
– |
Analyses identified differences primarily in the lower thoracic and upper lumbar spinal regions between the FP and AEP group and the FP and healthy group. In both instances, the FP group consistently operated in greater thoraco-lumbar spinal flexion. This was evident between the AEP and FP groups in the upper lumbar and lower thoracic region during all tasks, with the exception of the lower thoracic region during the reach up task (p = 0.103). Significant differences were observed between the FP and healthy groups in the lower thoracic region during the stand-to-sit and sit-to-stand tasks and during bending (and returning from) retrieving a pen from the floor. No significant differences were observed between the AEP and healthy groups in any spinal region. No between group significant differences were observed in the upper thoracic or lower lumbar regions during any task.
Discussion
This is the first study to identify distinct subgroup differences in lower thoracic spinal kinematics during functional activity which can aid in informing personalised rehabilitation strategies for CB-CFT interventions [11].
In-line with recent observations of lumbar movement in LBP subgroups [21], consistent patterns of different spinal movement in the thoraco-lumbar spine were noted between the NSCLBP subgroups throughout the functional tasks. In addition, this region is able to discriminate between the FP and healthy groups, highlighting that distinct increases in thoraco-lumbar flexion in the FP group. These findings support those of Dankaerts et al. [7], where differences were observed in usual sitting upper lumbar posture between AEP and FP groups. However, in contrast to the results reported here, Dankaerts et al. [7] observed differences between AEP and healthy individuals in the upper lumbar region, whilst no differences were observed between FP and healthy individuals. However, similarities are noted between the current study and adolescent cohort data, both identifying significant differences in usual sitting in the upper but not lower lumbar spine [9]. Both Dankaerts et al. [7] and Astfalck et al. [9] demonstrate significant differences between all three groups (FP, AEP, and healthy) in upper lumbar posture which were not replicated in this study. Differences in instrumentation (electromagnetic 3Space Fastrak®), subject numbers, and mean age (41.1 compared to 36.0 [7] and 15.6 [9] years) may account for some variation in results as well as observation of static postures rather than functional activities.
Overall, AEP individuals operated in significantly greater extension compared to FP during almost all functional tasks in upper lumbar and lower thoracic regions (p < 0.05). This may reflect the more extended nature of the task, where ROM in this region appears to be similar across all groups. The between group differences observed in the lower thoracic region are novel findings in this study. A non-significant trend (following adjustment for gender differences) for a reduction in overall trunk curvature in AEP compared to FP individuals has been observed previously in adolescent cohorts [22], suggesting that the AEP group may adopt a less kyphotic trunk posture compared to the FP group. However the methods utilised to calculate gross trunk angle do not allow for regional analysis.
Interestingly, no significant between group differences was identified between the AEP and healthy groups, contradicting previous work evaluating static postures [7, 10] and intimates that AEP and healthy individuals may utilise similar spinal movement patterns during functional tasks. There are multiple hypotheses for this observation. AEP individuals subjectively report extension-related activities as pain provocative due to a reduced capacity to control extension movement [5]. Therefore, the functional tasks may not have challenged the spine into substantial extension to elicit pain and maladaptive movement control. Patients often report prolonged exposure to static postures such as sitting and standing as provoking pain; therefore, extension may be more apparent in static postures compared to dynamic functional activity. There are also reported difficulties in accurately classifying AEP individuals, with approximately only 50–62% of AEP subjects correctly classified by experienced clinicians [23], since the AEP group displayed an overall higher risk of distress compared to the FP group other factors, such as maladaptive trunk muscle activity, or psychosocial factors [24], may be greater contributory mechanisms to pain than spinal movement.
Limitations and future work
The limitations include optoelectronic spinal measurement which allows only for evaluation of general spinal curvature, as opposed to underlying vertebral movement. Radiographic techniques (e.g., video fluoroscopy) are advancing in NSCLBP research [25] and are warranted to understand true vertebral movement during functional activity. Analysis of other NSCLBP MCI subgroups, trunk muscle activity, and psychosocial factors is required to better understand underlying pain mechanisms [24] as spinal movement alone appears insufficient to comprehensively explain subjectively reported pain presentations. Furthermore, explorations of how NSCLBP subgroups operate over prolonged time periods (using continuous postural measurement devices) will aid in understanding habitual spinal movement behaviours, carry-over between therapeutic sessions and longer term movement behaviour change. An important consideration is gender as a confounding factor (FP 77.8% male, AEP 82.6% female). Although this is reflective of previous MCI sub-grouped cohorts [7, 9], within-group gender distribution should be considered in future work evaluating the MDCS.
Clinical implications
The results support the MDCS as a clinical framework for subgrouping NSCLBP, and can inform the refinement of CB-CFT interventions by identifying key regions of differentiated spinal movement. There is strong evidence that individuals with NSCLBP MCI adopt thoraco-lumbar spinal movement behaviours which are consistent with the direction of subjectively reported patterns of pain provocation. Therefore, it is recommended that physical examination incorporates assessment of functional thoraco-lumbar spine movement, with treatment strategies incorporating targeted functional thoraco-lumbar movement re-education for FP individuals.
Conclusions
Regional spinal curvatures appear to distinctly differ in MCI subgroups, with the thoraco-lumbar region discriminating between FP and AEP, and FP and healthy groups during functional tasks. The FP group demonstrated more kyphotic postures in these spinal regions, whereas no significant differences between the AEP and healthy groups were observed, suggesting that these groups adopt more similar functional movement strategies. Alternatively, postures or activities may have needed to be more involved or sustained to elicit a response in these groups. The differences observed in the thoracic spine also highlight the importance of incorporating thoracic spine evaluation into NSCLBP assessment. Gender should also be considered as a confounding factor in future studies.
Notes
Acknowledgements
Support for the study is acknowledged from Health and Care Research Wales [formerly National Institute of Social, Health and Care (NISCHR) Wales] who provided research officers to support data collection.
Compliance with ethical standards
Conflict of interest
Dr. Rebecca Hemming received funding from Arthritis Research UK as part of the Arthritis Research UK Biomechanics and Bioengineering Centre, Cardiff University. Dr. Rebecca Hemming also received funding via a Presidents Scholarship Award, Cardiff University. For the remaining authors, none were declared.
Ethical approval
All procedures performed were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Supplementary material
References
-
1.Balagué F, Mannion AF, Pellisé F, Cedraschi C (2012) Non-specific low back pain. Lancet 379(9814):482–491CrossRefPubMedGoogle Scholar
-
2.Foster NE, Hill JC, O’Sullivan P, Hancock M (2013) Stratified models of care. Best Pract Res Clin Rheumatol 27(5):649–661CrossRefPubMedGoogle Scholar
-
3.Patel S, Friede T, Froud R, Evans DW, Underwood M (2013) Systematic review of randomized controlled trials of clinical prediction rules for physical therapy in low back pain. Spine 38(9):762–769. doi: 10.1097/BRS.0b013e31827b158f CrossRefPubMedGoogle Scholar
-
4.Foster NE, Hill JC, Hay EM (2011) Subgrouping patients with low back pain in primary care: are we getting any better at it? Man Ther 16(1):3–8. doi: 10.1016/j.math.2010.05.013 CrossRefPubMedGoogle Scholar
-
5.O’Sullivan P (2005) Diagnosis and classification of chronic low back pain disorders: maladaptive movement and motor control impairments as underlying mechanism. Man Ther 10:242–255CrossRefPubMedGoogle Scholar
-
6.O’Sullivan P (2004) Clinical instability of the lumbar spine. In: Boyling JD, Jull GA (eds) Grieve’s modern manual therapy: the vertebral column, 3rd edn. Elsevier, AmsterdamGoogle Scholar
-
7.Dankaerts W, O’Sullivan P, Burnett A, Straker L (2006) Differences in sitting postures are associated with nonspecific chronic low back pain disorders when patients are subclassified. Spine 31:698–704CrossRefPubMedGoogle Scholar
-
8.Dankaerts W, O’Sullivan P, Burnett A, Straker L (2006) Altered patterns of superficial trunk muscle activation during sitting in nonspecific chronic low back pain patients: importance of subclassification. Spine 31(17):2017–2023. doi: 10.1097/01.brs.0000228728.11076.82 CrossRefPubMedGoogle Scholar
-
9.Astfalck RG, O’Sullivan PB, Straker LM, Smith AJ, Burnett A, Caneiro JP, Dankaerts W (2010) Sitting postures and trunk muscle activity in adolescents with and without nonspecific chronic low back pain: an analysis based on subclassification. Spine 35(14):1387–1395CrossRefPubMedGoogle Scholar
-
10.Sheeran L, Sparkes V, Caterson B, Busse-Morris M, van Deursen R (2012) Spinal position sense and trunk muscle activity during sitting and standing in nonspecific chronic low back pain: classification analysis. Spine 37(8):E486–E495CrossRefPubMedGoogle Scholar
-
11.Fersum KV, O’Sullivan P, Skouen JS, Smith A, Kvale A (2013) Efficacy of classification-based cognitive functional therapy in patients with non-specific chronic low back pain: a randomized controlled trial. Eur J Pain 17(6):916–928. doi: 10.1002/j.1532-2149.2012.00252.x CrossRefGoogle Scholar
-
12.O’Sullivan P (2000) Lumbar segmental ‘instability’: clinical presentation and specific stabilising exercise management. Man Ther 5:2–12CrossRefPubMedGoogle Scholar
-
13.Von Korff M, Deyo RA, Cherkin D, Barlow W (1993) Back pain in primary care: outcomes at 1 year. Spine 18(7):855–862CrossRefGoogle Scholar
-
14.Fairbank JC, Couper J, Davies J, O’Brien J (1980) The Oswestry low back pain disability questionnaire. Physiotherapy 66:271–273PubMedGoogle Scholar
-
15.Main CJ, Wood PL, Hollis S, Spanswick CC, Waddell G (1992) The distress and risk assessment method. A simple patient classification to identify distress and evaluate the risk of poor outcome. Spine 17(1):42–52CrossRefPubMedGoogle Scholar
-
16.Miller RP, Kori SH, Todd DD (1991) The Tampa Scale: a measure of kinesiophobia. Unpublished Report, TampaGoogle Scholar
-
17.Simmonds MJ, Kumar S (1993) Health care ergonomics. Part II: location of body structures by palpation—a reliability study. Int J Ind Ergon 11(2):145–151. doi: 10.1016/0169-8141(93)90008-2 CrossRefGoogle Scholar
-
18.Field A (2009) Discovering statistics using SPSS. Sage, LondonGoogle Scholar
-
19.IBM (2012) The calculation of Bonferroni-adjusted p-values. IBM. http://www-01.ibm.com/support/docview.wss?uid=swg21476685. Accessed 05 Jan 2015
-
20.Landis JR, Koch GG (1977) The measurement of observer agreement for categorical data. Biometrics 33(1):159–174CrossRefPubMedGoogle Scholar
-
21.Marich AV, Hwang C-T, Salsich GB, Lang CE, Van Dillen LR (2017) Consistency of a lumbar movement pattern across functional activities in people with low back pain. Clin Biomech 44:45–51. doi: 10.1016/j.clinbiomech.2017.03.004 CrossRefGoogle Scholar
-
22.Astfalck RG, O’Sullivan PB, Straker LM, Smith AJ (2010) A detailed characterisation of pain, disability, physical and psychological features of a small group of adolescents with non-specific chronic low back pain. Man Ther 15(3):240–247. doi: 10.1016/j.math.2009.12.007 CrossRefPubMedGoogle Scholar
-
23.Fersum KV, O’Sullivan PB, Kvale A, Skouen JS (2009) Inter-examiner reliability of a classification system for patients with non-specific low back pain. Man Ther 14(5):555–561CrossRefGoogle Scholar
-
24.Linton SJ (2000) A review of psychological risk factors in back and neck pain. Spine 25(9):1148–1156CrossRefPubMedGoogle Scholar
-
25.Breen A, Breen A (2017) Uneven intervertebral motion sharing is related to disc degeneration and is greater in patients with chronic, non-specific low back pain: an in vivo, cross-sectional cohort comparison of intervertebral dynamics using quantitative fluoroscopy. Eur Spine J. doi: 10.1007/s00586-017-5155-y