Jonas Sandlund

ACuITY oF GoAL-DIRECTED ARM MoVEMENTS To VISIBLE TARGETS IN CHRoNIC NECK PAIN*

OBJECTIVE To evaluate end-point acuity in goal-directed arm movements in subjects with chronic neck pain, while taking the trade-off between speed and accuracy into account, and to evaluate associations between reduced acuity and self-rated characteristics. DESIGN Single-blinded, controlled, comparative group study. SUBJECTS Forty-five subjects with chronic non-traumatic, non-specific neck pain (n = 24) and whiplash-associated disorders (n = 21). Healthy subjects served as controls (n = 22). The groups were age- and sex-matched. METHODS Subjects performed fast and accurate pointing movements to a visual target. Group differences in end-point variability, controlled for peak velocity, were evaluated. Associations between end-point variability and self-rated symptoms, functioning, self-efficacy and kinesiophobia were analysed. RESULTS End-point acuity, controlled for peak velocity, was reduced for both neck-pain groups. Similar spatial error patterns across all groups indicated no direction-specific reduction. For both neck-pain groups, associations were found between end-point acuity and neck movement deficits, physical functioning and, in whiplash, also balance and pain. CONCLUSION Acuity of goal-directed arm movements can be reduced in chronic neck pain. Associations between acuity and self-rated characteristics support the clinical validity of the results and indicate that impaired neck function contributes to reduced end-point acuity. The results can be of importance for characterization and rehabilitation of neck disorders.

Differences in motor variability among individuals performing a standardized short-cycle manual task

Motor variability (MV) has been suggested to be a determinant of the risk for developing musculoskeletal disorders in repetitive work. In this study we examined whether individuals consistently differed in the extent of motor variability when performing a standardized short-cycle manual task. On three separate days, arm kinematics was recorded in 14 healthy subjects performing a pipetting task, transferring liquid from a pick-up tube to eight target tubes with a cycle time of 2.8s. Cycle-to-cycle standard deviations (SD) of a large selection of shoulder and elbow kinematic variables, were processed using principal component analysis (PCA). Thereafter, between-subjects and between-days (within-subject) variance components were calculated using a random effects model for each of four extracted principal components. The results showed that MV differed consistently between subjects (95% confidence intervals of the between-subjects variances did not include zero) and that subjects differed consistently in MV between days. Thus, our results support the notion that MV may be a consistent personal trait, even though further research is needed to verify whether individuals rank consistently in MV even across tasks. If so, MV may be a candidate determinant of the risk of developing fatigue and musculoskeletal disorders in repetitive occupational work.

Do we see the same movement impairments? The inter-rater reliability of movement tests for experienced and novice physiotherapists

Abstract Study design: Inter-rater reliability study. Background: Physiotherapists (PTs) use clinical tests including movement tests to identify faulty movement patterns. Aims: To investigate the inter-rater-reliability of active movement tests in the cervical spine, shoulder joint and scapulo-thoracic joint, and to describe the reasons for judgment of a positive test. Methodology: Four PTs, two experienced and two recently educated (novice), rated performance of five movement tests for 36 participants. Twenty-one of the participants were patients under treatment because of neck and/or shoulder problems, while 15 participants declared no problem from this region of the body. All tests were video recorded and the ratings were done by observing the video recordings. First, the PTs judged the tests as negative (the movement being ideally performed) or positive (the movement not being ideally performed). Then, the PTs described why the movements that they judged positive were not being ideally performed, using a predefined protocol, which represented different movement quality aspects. The inter-rater reliability was calculated for each test using Kappa statistics between the two experienced and the two novice PTs, respectively, and between each of the experienced and each of the novice PTs. Major findings: The experienced PTs had a higher inter-rater reliability than the novice PTs. The reasons for considering a movement test being positive differed highly between the (novice) PTs. Principal conclusion: This study supports previous studies concluding that the observation of active movement tests is reliable when assessed by experienced PTs. Novice PTs might benefit from further supervision.