Roren A1,2,3, Acapo S4, Blasco A1, Lefevre-Colau M-M1, Nguyen C1, Roby-Brami A5
1AP-HP, Cochin Hospital, Department of Physical and Rehabilitation Medicine, Paris, France, 2INSERM UMR 1153, Centre of Research in Epidemiology and Statistics Sorbonne Paris Cité, ECAMO Team, Paris, France, 3Federative Institute of Research on Disability, Paris, France, 4University of Nantes, Department of Medicine and Medical Technology, Nantes, France, 5CNRS UMR 7222, INSERM U 1150, Institute of Intelligent Systems and Robotics, Paris, France
Background: Biomechanical studies have shown that maximal humero-thoracic elevation is limited to 150°. Nevertheless, a healthy person can elevate their arm vertically, which suggests that other joints contribute to maximal arm elevation; Maximal arm elevation in healthy subjects involves trunk 3D rotations. However, the specific contribution of the cervical spine is unknown.
Purpose: We aimed to assess the cervical spine kinematics during maximal arm elevation in healthy individuals.
Methods: We conducted a cross-sectional study from April to June 2016 in 10 healthy volunteers. 3D head and trunk rotations during active unilateral arm elevation were recorded in sagittal, frontal and scapular planes by using a Polhemus Fastrak electromagnetic device. The 3D orientation of the trunk and head in space and the head by reference to the trunk (head/trunk) were compared at 30°, 90°, 140° and maximal arm elevation by using Bayesian ANOVA and Wilcoxon test.
Results: Unilateral active maximal arm elevation involved a combined 3D kinematic pattern of flexion, ipsilateral bending and contralateral axial rotation of the head/trunk. 3D rotations of the head/trunk were synergic and similar in range of motion but opposite in direction to that of the trunk. Trunk and head/trunk orientations were tuned to the level and plane of arm elevation. Head orientation in space remained relatively constant.
Conclusion(s): Our results suggest that the cervical spine compensates for trunk rotations during arm elevation so that the orientation of the head remains relatively stable for horizontal gaze, and that the whole spine contributes to the kinematic chain of maximal arm elevation.
Implications: The mobility of the arm, trunk and cervical spine are finely related. The rehabilitation of patients with shoulder disorders involving reduced range of motion should consider this finding in order to increase or decrease the mobility of the spine according to the objective pursued (recovery of shoulder range of motion or development of compensation strategies).
Keywords: 3D kinematics,, cervical spine, arm elevation
Funding acknowledgements: There are no sources of funding and no commercial relationship which may lead to conflict of interest.
Purpose: We aimed to assess the cervical spine kinematics during maximal arm elevation in healthy individuals.
Methods: We conducted a cross-sectional study from April to June 2016 in 10 healthy volunteers. 3D head and trunk rotations during active unilateral arm elevation were recorded in sagittal, frontal and scapular planes by using a Polhemus Fastrak electromagnetic device. The 3D orientation of the trunk and head in space and the head by reference to the trunk (head/trunk) were compared at 30°, 90°, 140° and maximal arm elevation by using Bayesian ANOVA and Wilcoxon test.
Results: Unilateral active maximal arm elevation involved a combined 3D kinematic pattern of flexion, ipsilateral bending and contralateral axial rotation of the head/trunk. 3D rotations of the head/trunk were synergic and similar in range of motion but opposite in direction to that of the trunk. Trunk and head/trunk orientations were tuned to the level and plane of arm elevation. Head orientation in space remained relatively constant.
Conclusion(s): Our results suggest that the cervical spine compensates for trunk rotations during arm elevation so that the orientation of the head remains relatively stable for horizontal gaze, and that the whole spine contributes to the kinematic chain of maximal arm elevation.
Implications: The mobility of the arm, trunk and cervical spine are finely related. The rehabilitation of patients with shoulder disorders involving reduced range of motion should consider this finding in order to increase or decrease the mobility of the spine according to the objective pursued (recovery of shoulder range of motion or development of compensation strategies).
Keywords: 3D kinematics,, cervical spine, arm elevation
Funding acknowledgements: There are no sources of funding and no commercial relationship which may lead to conflict of interest.
Topic: Human movement analysis; Musculoskeletal: upper limb; Musculoskeletal: spine
Ethics approval required: Yes
Institution: CPP-IDFIII,
Ethics committee: Local institutional review board
Ethics number: no. 2013-A00660-45
All authors, affiliations and abstracts have been published as submitted.
