Reliability of Scapular Kinematics Measured with Electromagnetic Tracking System during Scaption

Faculty Mentor

Bryan L. Riemann

Location

Savannah Ballroom

Type of Research

Completed

Session Format

Poster Presentation

College

Waters College of Health Professions

Department

Tactical and Occupational Performance Institute

Abstract

Reliability of Scapular Kinematics Measured with Electromagnetic Tracking During Arm Elevation in the Scapular Plane

Victoire Komlan, Sandra John, Emma Williams, Joseph Kardouini, Bryan L Riemann

Scaption, or arm elevation in the plane of the scapula, is a commonly used task to assess the synergy of scapular-humeral-thoracic (SHT) movement. Quantification of SHT movement can be made using an electromagnetic (EM) tracking system. Local axes are created on the thorax, scapula, and humerus by digitizing standard bony landmarks. In addition to the digitization process potentially being a source of error, there is also variability in the performance of the scaption task. Thus, establishing the reliability of scapular measurements during scaption is critical. Therefore, the purpose of this study was to evaluate the between session reliability of scapular kinematic measurements obtained using an EM tracking system during scaption.

Method: Twenty-one healthy young adult participants (10 females, 11 males) were recruited for this study. After EM sensors were secured to the thorax (7 th cervical vertebrae), scapulae (acromion process), and humeri (inferior to deltoid insertion), 25 bony landmarks were digitized to establish anatomical local coordinate systems on each segment. Next, participants performed five repetitions of scaption while holding a hand weight (1.36 kg for individuals weighing < 68 kg; 2.27 kg for individuals weighing ≥68 kg). Following completion of the task, each participant’s bony landmarks were re-digitized, and the same protocol was repeated. Thoracic extension (TE), scapular internal rotation (SIR), scapular upward rotation (SUR), clavicular elevation (CE), clavicular protraction (CP) at 30°, 60°, and 90° of humeral elevation were computed. Scapular kinematics were examined as per the International Society of Biomechanics protocol for measuring scapular and glenohumeral kinematics. Normality and heteroscedasticity of the session differences were evaluated with Shapiro-Wilk and Kendall’s Tau tests, respectively. Systematic bias was examined using a paired t-test, while standard error of measurement (SEM) established absolute reliability. Intraclass correlation coefficients (ICC, model: 2,1) established the relative reliability.

Results: Except for a slight normality departure for SP at 60° (P=0.04), all other measurement differences were normally distributed (P>0.10). There was no significant heteroscedasticity (τ=- 0.30 to 0.19, P< 0.06). There was no significant bias between the sessions (-0.5±2.9 to 1.0±2.9°, P=0.08 to 0.96). For absolute reliability, SIR (2.1 to 3.0°) exhibited the largest SEM while SUR (1.6 to 2.0), SE (0.9 to 1.4°), and SP (1.3 to 1.8°) were ≤2.0°. The ICC for scapular measurements ranged from 0.80 (SE at 60°) to 0.97 (SUR at 90°).

Discussion: Good to excellent reliability was shown for examining shoulder girdle kinematics using and electromagnetic tracking system. The error rates can be used to interpret findings of studies in relation to measurement error and detectable change. The slightly higher absolute reliability is likely explained by humeral plane of elevation variations in performance of the task.

Practical Applications: These results demonstrate measurement of scapular movement during scaption with an EM tracking system to be reliable, supporting the application in evaluating shoulder mechanics. Clinicians and researchers may employ this approach to assess scapular kinematics, monitor movement alterations associated with pathological conditions load carriage across the shoulder girdle, track rehabilitation progress, and evaluate the effects of interventions.

Program Description

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Start Date

4-21-2026 10:00 AM

End Date

4-21-2026 12:00 PM

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Apr 21st, 10:00 AM Apr 21st, 12:00 PM

Reliability of Scapular Kinematics Measured with Electromagnetic Tracking System during Scaption

Savannah Ballroom

Reliability of Scapular Kinematics Measured with Electromagnetic Tracking During Arm Elevation in the Scapular Plane

Victoire Komlan, Sandra John, Emma Williams, Joseph Kardouini, Bryan L Riemann

Scaption, or arm elevation in the plane of the scapula, is a commonly used task to assess the synergy of scapular-humeral-thoracic (SHT) movement. Quantification of SHT movement can be made using an electromagnetic (EM) tracking system. Local axes are created on the thorax, scapula, and humerus by digitizing standard bony landmarks. In addition to the digitization process potentially being a source of error, there is also variability in the performance of the scaption task. Thus, establishing the reliability of scapular measurements during scaption is critical. Therefore, the purpose of this study was to evaluate the between session reliability of scapular kinematic measurements obtained using an EM tracking system during scaption.

Method: Twenty-one healthy young adult participants (10 females, 11 males) were recruited for this study. After EM sensors were secured to the thorax (7 th cervical vertebrae), scapulae (acromion process), and humeri (inferior to deltoid insertion), 25 bony landmarks were digitized to establish anatomical local coordinate systems on each segment. Next, participants performed five repetitions of scaption while holding a hand weight (1.36 kg for individuals weighing < 68 kg; 2.27 kg for individuals weighing ≥68 kg). Following completion of the task, each participant’s bony landmarks were re-digitized, and the same protocol was repeated. Thoracic extension (TE), scapular internal rotation (SIR), scapular upward rotation (SUR), clavicular elevation (CE), clavicular protraction (CP) at 30°, 60°, and 90° of humeral elevation were computed. Scapular kinematics were examined as per the International Society of Biomechanics protocol for measuring scapular and glenohumeral kinematics. Normality and heteroscedasticity of the session differences were evaluated with Shapiro-Wilk and Kendall’s Tau tests, respectively. Systematic bias was examined using a paired t-test, while standard error of measurement (SEM) established absolute reliability. Intraclass correlation coefficients (ICC, model: 2,1) established the relative reliability.

Results: Except for a slight normality departure for SP at 60° (P=0.04), all other measurement differences were normally distributed (P>0.10). There was no significant heteroscedasticity (τ=- 0.30 to 0.19, P< 0.06). There was no significant bias between the sessions (-0.5±2.9 to 1.0±2.9°, P=0.08 to 0.96). For absolute reliability, SIR (2.1 to 3.0°) exhibited the largest SEM while SUR (1.6 to 2.0), SE (0.9 to 1.4°), and SP (1.3 to 1.8°) were ≤2.0°. The ICC for scapular measurements ranged from 0.80 (SE at 60°) to 0.97 (SUR at 90°).

Discussion: Good to excellent reliability was shown for examining shoulder girdle kinematics using and electromagnetic tracking system. The error rates can be used to interpret findings of studies in relation to measurement error and detectable change. The slightly higher absolute reliability is likely explained by humeral plane of elevation variations in performance of the task.

Practical Applications: These results demonstrate measurement of scapular movement during scaption with an EM tracking system to be reliable, supporting the application in evaluating shoulder mechanics. Clinicians and researchers may employ this approach to assess scapular kinematics, monitor movement alterations associated with pathological conditions load carriage across the shoulder girdle, track rehabilitation progress, and evaluate the effects of interventions.