Rossi D.1, Resende R.2, Fonseca S.2, Oliveira A.1
1University of Sao Paulo, Department of Biomechanics, Medicine and Rehabilitation of Locomotor, Ribeirao Preto, Brazil, 2Universidade Federal de Minas Gerais, Department of Physiotherapy, School of Physical Education, Physiotherapy and Occupational Therapy, Belo Horizonte, Brazil
Background: The 'optimal' scapular motion has been considered essential to the functioning of the shoulder. However, the scapular dyskinesis (SD) still presents some challenges related to diagnostic measurements and the relationship with presence of shoulder symptoms.
Purpose: To compare the pain intensity, the shoulder disability and the scapulothoraric kinematic pattern in shoulder pain patients with and without scapular dyskinesis.
Methods: Twenty-three shoulder pain patients (49 ± 7 yrs; 72 ± 13 kg; 166 ± 1 cm) were evaluated. Inclusion criteria included painful arc and positive impingement tests. This study was approved by the local Ethics Research Committee (protocol 084/2011) and all subjects provided written informed consent. An experienced examiner classified the participants concerning to the scapular dyskinesis by using a qualitative yes/no category proposed by a recent consensus. Pain intensity (Pain Numeric Rating Scale), shoulder disability (Shoulder Pain and Disability Index SPADI questionnaire) and scapulothoracic kinematic were evaluated. Three-dimensional position and orientation of each subjects thorax, scapular and humerus were tracked using electromagnetic Liberty ® (Polhemus Inc) system according to ISB international recommendations. Kinematic data analysis for scapular orientation was performed for selected angles during arm lowering (120˚, 90˚, 60˚, and 30˚) in the sagittal plane. The scapulothoracic phase-plane graph was analyzed by plotting the angular displacement and the angular velocity of the downward scapular rotation during the arm lowering. Statistical comparisons were done with the SPSS and Matlab software. A Student t test was used to compare the pain intensity, SPADI and the kinematic angles. The 95% minimal detectable change band was used to compare the downward scapular rotation phase-plane graph.
Results: From twelve patients classified as having SD, 69% presented this condition bilaterally, 69% presented shoulder pain in the dominant member, and only 30% presented SD in a static position. We did not find differences in the pain intensity, shoulder disability and kinematic angles (p 0.05). Both groups presented a moderate pain intensity. The SPADI questionnaire values were around 50 points, which closer to 100 points worse is the disability condition, with a mean difference of 5 points between groups (p = 0. 42, effect size = 0.35). During the lowering arm, both groups presented progressive scapular downward rotation, anterior tilt and variable external/internal rotation, but no difference was found between groups. When analyzed phase-plane graph, scapular downward rotation velocity increased and gradually decreased as the arm reaches the side of the body. We found the same pattern in both groups, however, the SD group average curve comes out the 95% minimal detectable change band resulting in a pattern that is distinct from the pattern of people without SD.
Conclusion(s): SD presence did not affect the pain intensity, the shoulder disability and the amount of scapular movements at selected point of arm lowering in shoulder pain patients. However, people with pain and SD associated presented a distinct pattern of neuromuscular scapular control during arm lowering.
Implications: Our findings could improve understanding of scapular dyskinesis patterns in shoulder pain patients and improve clinicians ability to visually assess and treat this condition.
Funding acknowledgements: We would like to acknowledge São Paulo Research Foundation (FAPESP - Grant No. 2014/09485-0) that supported this work.
Topic: Musculoskeletal: peripheral
Ethics approval: This study was approved by the Ethics Research Committee from Ribeirão Preto Medical School (protocol number 084/2011).
All authors, affiliations and abstracts have been published as submitted.
