Reliability of the Harris Hip limping sub-score in patients undergoing total hip arthroplasty.

PURPOSE: In patients undergoing total hip arthroplasty, limping is a significant symptom, often assessed with the limping sub-score of the Harris Hip Score. However, the reliability of this sub-score has not been specifically investigated. The purpose of this study is to investigate the intra- and inter-rater reliability of this sub-score. METHODS: Thirty patients undergoing THA were recruited and performed a gait analysis before surgery and three months after surgery. In addition, 30 asymptomatic participants were included. In total, 90 visits were analysed in this study. The HHS limping sub-score was assessed for each visit using a video (front and back view side-by-side) of a ten metre walk at a self-selected speed. Two orthopaedic surgeons evaluated the limping of each video in two different grading sessions with a one week delay. To avoid recall bias, the patient's number identity was randomized and different for each grading session and each rater. The weighted Cohen's Kappa coefficient was used to quantify the intra- and inter-reliability. The reliability of three components was studied: the presence of limping, its severity, and the compensation type. RESULTS: For all components, the agreement for intra-rater reliability ranged from moderate to strong and from none to moderate for the inter-rater reliability. CONCLUSION: These results do not encourage the use of HHS-limping sub-score for data involving different raters in both clinical and research contexts. It calls for improved consensus on limping definitions or the creation of objective measures.

Sensor-to-Bone Calibration with the Fusion of IMU and Bi-Plane X-rays.

Inertial measurement units (IMUs) need sensor-to-segment calibration to measure human kinematics. Multiple methods exist, but, when assessing populations with locomotor function pathologies, multiple limitations arise, including holding postures (limited by joint pain and stiffness), performing specific tasks (limited by lack of selectivity) or hypothesis on limb alignment (limited by bone deformity and joint stiffness). We propose a sensor-to-bone calibration based on bi-plane X-rays and a specifically designed fusion box to measure IMU orientation with respect to underlying bones. Eight patients undergoing total hip arthroplasty with bi-plane X-rays in their clinical pathway participated in the study. Patients underwent bi-plane X-rays with fusion box and skin markers followed by a gait analysis with IMUs and a marker-based method. The validity of the pelvis, thigh and hip kinematics measured with a conventional sensor-to-segment calibration and with the sensor-to-bone calibration were compared. Results showed (1) the feasibility of the fusion of bi-plane X-rays and IMUs in measuring the orientation of anatomical axes, and (2) higher validity of the sensor-to-bone calibration for the pelvic tilt and similar validity for other degrees of freedom. The main strength of this novel calibration is to remove conventional hypotheses on joint and segment orientations that are frequently violated in pathological populations.

Sensitivity and specificity of the flexion and extension relaxation ratios to identify altered paraspinal muscles' flexion relaxation phenomenon in nonspecific chronic low back pain patients.

BACKGROUND: Among the main methods used to identify an altered flexion relaxation phenomenon (FRP) in nonspecific chronic low back pain (NSCLBP), it has been previously demonstrated that flexion relaxation ratio (FRR) and extension relaxation ratio (ERR) are more objective than the visual reference method. OBJECTIVE: To determine the sensitivity and specificity of the different methods used to calculate the ratios in terms of their ability to identify an altered FRP in NSCLBP. METHODS: Forty-four NSCLBP patients performed a standing maximal trunk flexion task. Surface electromyography (sEMG) was recorded along the erector spinae longissimus (ESL) and multifidus (MF) muscles. Altered FRP based on sEMG was visually identified by three experts (current standard). Six FRR methods and five ERR methods were used both for the ESL and MF muscles. ROC curves (with areas under the curve (AUC) and sensitivity/specificity) were generated for each ratio. RESULTS: All methods used to calculate these ratios had an AUC higher than 0.9, excellent sensitivity (>90 %), and good specificity (80-100 %) for both ESL and MF muscles. CONCLUSION: Both FRP ratios (FRR and ERR) for MF and ESL muscles, appear to be an objective, sensitive and specific method for identifying altered FRP in NSCLBP patients.

The SWING test: A more reliable test than passive clinical tests for assessing sagittal plane hip mobility.

BACKGROUND: Clinical assessment of sagittal plane hip mobility is usually performed using the Modified Thomas Test (for extension) and the Straight-Leg-Raise (for flexion) with a goniometer. These tests have limited reliability, however. An active swinging leg movement test (the SWING test), assessed using 3D motion analysis, could provide an alternative to these passive clinical tests. RESEARCH QUESTION: Is the SWING test a more reliable alternative to evaluate hip mobility, in comparison to the clinical extension and flexion tests? METHODS: Ten asymptomatic adult participants were evaluated by two investigators over three sessions. Participants performed 10 maximal hip extensions and flexions, with both legs straight and no trunk movement (the SWING test). Hip kinematics was assessed using a 3D motion analysis system. Maximal and minimal hip angles were calculated for each swing and represented maximal hip flexion (SWING flexion) and extension (SWING extension), respectively. The Modified Thomas Test and Straight-Leg-Raise were repeated 3 times for each leg. On the first day, both investigators performed all the tests (SWING + Modified Thomas Test + Straight-Leg-Raise). A week later, a single investigator repeated all the tests. Inter-rater, intra-rater, within-day and between-day reliability were evaluated using intra-class correlation. RESULTS: Intra-class correlation coefficients for all the tests were superior to 0.8, except for the Modified Thomas Test's intra-rater, between-day (intra-class correlation 0.673) and the Straight-Leg-Raise's inter-rater, within-day (intra-class correlation 0.294). The SWING test always showed a higher intra-class correlation coefficient than the passive clinical tests. The only significant correlation found was for the Straight-Leg-Raise and SWING flexion (r = 0.48; P < 0.001). SIGNIFICANCE: The SWING test seems to be an alternative to existing passive clinical tests, offering better reliability for assessing sagittal plane hip mobility.

A systematic review of movement and muscular activity biomarkers to discriminate non-specific chronic low back pain patients from an asymptomatic population.

The identification of relevant and valid biomarkers to distinguish patients with non-specific chronic low back pain (NSCLBP) from an asymptomatic population in terms of musculoskeletal factors could contribute to patient follow-up and to evaluate therapeutic strategies. Several parameters related to movement and/or muscular activity impairments have been proposed in the literature in that respect. In this article, we propose a systematic and comprehensive review of these parameters (i.e. potential biomarkers) and related measurement properties. This systematic review (PROSPERO registration number: CRD42020144877) was conducted in Medline, Embase, and Web of Knowledge databases until July 2019. In the included studies, all movements or muscular activity parameters having demonstrated at least a moderate level of construct validity were defined as biomarkers, and their measurement properties were assessed. In total, 92 studies were included. This allowed to identify 121 movement and 150 muscular activity biomarkers. An extensive measurement properties assessment was found in 31 movement and 14 muscular activity biomarkers. On the whole, these biomarkers support the primary biomechanical concepts proposed for low back pain. However, a consensus concerning a robust and standardised biomechanical approach to assess low back pain is needed.

Can the fusion of motion capture and 3D medical imaging reduce the extrinsic variability due to marker misplacements?

In clinical gait analysis, measurement errors impede the reliability and repeatability of the measurements. This extrinsic variability can potentially mislead the clinical interpretation of the analysis and should thus be minimised. Skin marker misplacement has been identified as the largest source of extrinsic variability between measurements. The goal of this study was to test whether the fusion of motion capture and 3D medical imaging could reduce extrinsic variability due to skin marker misplacement. The fusion method consists in using anatomical landmarks identified with 3D medical imaging to correct marker misplacements. To assess the reduction of variability accountable to the fusion method, skin marker misplacements were voluntarily introduced in the measurement of the pelvis and hip kinematics during gait for two patients scheduled for unilateral hip arthroplasty and two patients that underwent unilateral hip arthroplasty. The root mean square deviation was reduced by -78 ± 15% and the range of variability by -80 ± 16% for the pelvis and hip kinematics in average. These results showed that the fusion method could significantly reduce the extrinsic variability due to skin marker misplacement and thus increase the reliability and repeatability of motion capture measurements. However, the identification of anatomical landmarks via medical imaging is a new source of extrinsic variability that should be assessed before considering the fusion method for clinical applications.

Flexion-Relaxation Ratio Asymmetry and Its Relation With Trunk Lateral ROM in Individuals With and Without Chronic Nonspecific Low Back Pain.

STUDY DESIGN: A cross-sectional comparative study. OBJECTIVE: The present study aimed to investigate the relationship between the FR phenomenon asymmetry of lumbar muscles and trunk lateral range of motion (ROM) asymmetry in nonspecific chronic low back pain (NSCLBP) patients. SUMMARY OF BACKGROUND DATA: Imbalance in trunk muscle activation between right and left sides can induce pain by loading the spine incorrectly, especially in patients with NSCLBP. A previous study reported a greater asymmetry in the FR phenomenon of the erector spinae in NSCLBP patients than in asymptomatic participants (APs). Imbalance of muscle properties, such as trunk ROM, has been suggested as a possible cause of this observed asymmetry. METHODS: Twenty-eight NSCLBP patients and 22 AP performed 3 standing maximal trunk flexions. Surface electromyography was recorded bilaterally for erector spinae longissimus and lumbar multifidus. A FR ratio was calculated for each muscle. The fingertip-to-thigh test was performed to assess trunk lateral ROM. Each parameter's asymmetry was calculated as the absolute difference between right and left sides. RESULTS: NSCLBP patients present a significantly lower trunk lateral ROM than AP. FR ratio asymmetry of the erector spinae was significantly greater in NSCLBP patients than in AP (P < 0.05). FR ratio asymmetry of the multifidus and trunk lateral ROM asymmetry were not significantly different between groups. Significant correlation (r = 0.49) between FR ratio asymmetry of erector spinae and trunk lateral ROM asymmetry was observed only for patients with NSCLBP. CONCLUSION: The present findings showed that FR ratio asymmetry of erector spinae longissimus is moderately correlated with trunk lateral ROM asymmetry. In addition, the results confirmed that patients with NSCLBP present a reduced trunk lateral ROM, a FR ratio asymmetry of the erector spinae which is correlated with trunk rotation. These findings suggested an imbalance spine loading which can contribute to the persistence of pain. LEVEL OF EVIDENCE: 3.

Asymmetry of lumbar muscles fatigability with non-specific chronic low back pain patients.

PURPOSE: Non-specific chronic low back pain (NSCLBP) patients present with reduced back extensor muscle endurance which could be explained by the higher fatigability of their lumbar muscles. However, studies investigating lumbar muscle fatigability have shown contradictory findings. Furthermore, none investigated potential asymmetry in lumbar muscle fatigability, despite neuromuscular asymmetry being reported as a risk factor for NSCLBP. The present study's primary purpose was to determine whether NSCLBP patients presented with higher lumbar muscle fatigability and fatigability asymmetry than asymptomatic participants. METHODS: Thirty NSCLBP patients and 23 asymptomatic participants performed the Sorensen test. The median frequencies from the electromyographs of the right and left erector spinae longissimus (ESL) and lumbar multifidus (LMF) were measured during the test. A linear regression was performed on the median frequencies on each muscle. Slope and initial median frequency were extracted to characterize fatigability. Asymmetry was quantified by the absolute differences between right-side and left-side muscle pairs. RESULTS: NSCLBP patients presented significantly poorer back extensor muscle endurance than asymptomatic participants. No differences were found between NSCLBP patients and asymptomatic participants in terms of fatigability or fatigability asymmetry for either the ESL or LMF. The initial median frequency in both muscles was significantly lower among NSCLBP patients. CONCLUSIONS: The present study showed that NSCLBP patients did not present higher fatigability or higher fatigability asymmetry in lumbar muscles than asymptomatic participants. The heterogeneity of the NSCLBP population, due to the absence of any specific etiology, may explain these findings. These slides can be retrieved under Electronic Supplementary Material.

Identifying Subgroups of Patients With Chronic Nonspecific Low Back Pain Based on a Multifactorial Approach: Protocol For a Prospective Study.

BACKGROUND: Low back pain, especially nonspecific chronic low back pain (LBP), the leading cause of disability worldwide, represents both social and economic problems. Different therapeutic management techniques can be used, but their effects vary. Clinicians and researchers attribute the variation in the efficacy of therapeutic and management techniques to the heterogeneity of the nonspecific chronic low back pain population, and they agree that nonspecific chronic LBP must be subgrouped. OBJECTIVE: This study aims to identify nonspecific chronic LBP subgroups based on a multifactorial approach, including biomechanical, physical, and psychosocial data. METHODS: A total of 100 nonspecific chronic LBP patients and 30 healthy participants aged between 18 and 60 years will be recruited for this prospective study. A psychosocial profile will be established using questionnaires on anxiety, depression, functional disability, pain, fear of pain, avoidance belief, and physical activity. A physical capacity evaluation will be conducted. It will evaluate flexibility of the hips, lumbar spine, and lateral thoracolumbar segment, as well as trunk (extensor and flexor) muscle endurance. The subjects will perform functional daily life activities, such as walking, object lifting, forward bending, sit-to-stand, stand-to-sit, balance, and usual postures. Full body kinematics, kinetics, and surface electromyography of the trunk and hip muscles will be assessed during these tasks. The clustering classification methods for the statistical analysis will be determined according to the data and will be used to identify the subgroups of nonspecific chronic LBP patients. RESULTS: Data collection started in September 2017 and will be completed with the inclusion of all the participants (100 nonspecific chronic LBP and 30 control). The study results will be published in peer-reviewed journals and presented at relevant international conferences. CONCLUSIONS: Numerous studies have showed that the therapeutic management of nonspecific chronic LBP is difficult and has inconstant effects caused by the complexity and heterogeneity of nonspecific chronic LBP. Identifying subgroups with a multifactorial approach is more comprehensive and closer to the pathophysiology of nonspecific chronic LBP. It also represents benefit interests and a challenge both clinically and socially. The perspective of this study is expected to support clinicians for a more adapted therapeutic management for each subgroup.

EMG normalization method based on grade 3 of manual muscle testing: Within- and between-day reliability of normalization tasks and application to gait analysis.

Electromyography (EMG) is an important parameter in Clinical Gait Analysis (CGA), and is generally interpreted with timing of activation. EMG amplitude comparisons between individuals, muscles or days need normalization. There is no consensus on existing methods. The gold standard, maximum voluntary isometric contraction (MVIC), is not adapted to pathological populations because patients are often unable to perform an MVIC. The normalization method inspired by the isometric grade 3 of manual muscle testing (isoMMT3), which is the ability of a muscle to maintain a position against gravity, could be an interesting alternative. The aim of this study was to evaluate the within- and between-day reliability of the isoMMT3 EMG normalizing method during gait compared with the conventional MVIC method. Lower limb muscles EMG (gluteus medius, rectus femoris, tibialis anterior, semitendinosus) were recorded bilaterally in nine healthy participants (five males, aged 29.7±6.2years, BMI 22.7±3.3kgm-2) giving a total of 18 independent legs. Three repeated measurements of the isoMMT3 and MVIC exercises were performed with an EMG recording. EMG amplitude of the muscles during gait was normalized by these two methods. This protocol was repeated one week later. Within- and between-day reliability of normalization tasks were similar for isoMMT3 and MVIC methods. Within- and between-day reliability of gait EMG normalized by isoMMT3 was higher than with MVIC normalization. These results indicate that EMG normalization using isoMMT3 is a reliable method with no special equipment needed and will support CGA interpretation. The next step will be to evaluate this method in pathological populations.

Effects of a Worksite Supervised Adapted Physical Activity Program on Trunk Muscle Endurance, Flexibility, and Pain Sensitivity Among Vineyard Workers.

OBJECTIVES: In viticulture, the prevalence of low back pain is particularly high among vineyard workers exposed to sustained and awkward postures. One promising setting for low back pain prevention resides in the implementation of workplace physical activity. METHODS: This nonrandomized pilot study aims at evaluating the effects of a worksite supervised adapted physical activity program among 17 vineyard workers volunteered to enter either an intervention group (n = 10) or a control group (n = 7).The intervention group followed a physical activity program for 8 weeks involving (1) 15 minutes of warm-up every working day and (2) two weekly 1-hour adapted physical activity sessions targeting trunk muscle endurance and flexibility. The control group was advised to continue normal physical activity. Evaluations were carried out at weeks 0, 4, 8, and 12. Physical capacity was assessed using flexibility tests for the trunk, along with trunk muscle flexor and extensor endurance tests. Finally, pain sensitivity was evaluated by assessing pressure pain thresholds over 14 anatomical locations in the low back region. RESULTS: For the intervention group, the endurance of the trunk extensor and flexor significantly increased from baseline to week 8 as well as the pressure pain thresholds. No change was observed for the control group over the same period. CONCLUSIONS: These encouraging results in combination with the high adherence rate set interesting foundations for the promotion of worksite supervised adapted physical activity and, most likely, offer a new promising approach to prevent low back pain among vineyard workers.

Trunk kinematics and low back pain during pruning among vineyard workers-A field study at the Chateau Larose-Trintaudon.

The prevalence of low back disorders is dramatically high in viticulture. Field measurements that objectively quantify work exposure can provide information on the relationship between the adopted trunk postures and low back pain. The purposes of the present study were three-fold (1) to carry out a kinematics analysis of vineyard-workers' pruning activity by extracting the duration of bending and rotation of the trunk, (2) to question separately the relationship between the duration of forward bending or trunk rotation with low back pain intensity and pressure pain sensitivity and (3) to question the relationship between the combined duration of forward bending and trunk rotation on low back pain intensity and pressure pain sensitivity. Fifteen vineyard-workers were asked to perform pruning activity for 12 minutes with a wireless triaxial accelerometer placed on their trunk. Kinematic analysis of the trunk showed that vineyard-workers spent more than 50% of the time with the trunk flexed greater than 30° and more than 20% with the trunk rotated greater than 10°. These results show that pruning activity lead to the adoption of forward bended and rotated trunk postures that could significantly increase the risk of work related musculoskeletal disorders in the low back. However, this result was mitigated by the observation of an absence of significant association between the duration of forward bending and trunk rotation with low back pain intensity or pressure pain sensitivity. Even if prospective field measurements and studies assessing the effects of low back pain confounders are needed, this field study provides new genuine information on trunk kinematics during pruning activity.