Evidence-Based Practice – Issue 7-2015
Internal Rotation Behind-the-Back Angle: A Reliable Angular Measurement for Shoulder Internal Rotation Behind the Back
Article. Sraj SA. Internal Rotation Behind-the-Back Angle: A Reliable Angular Measurement for Shoulder Internal Rotation Behind the Back. Sports Health 2015; 7(4): 299-302.
Purpose. The purpose of this study was to assess the intra- and inter- observer reliability of a novel approach to objectifying shoulder internal rotation by a behind-the-back measure.
Study Design. Descriptive laboratory study
Methods
- Subjects
- 60 healthy volunteers without shoulder pathology
- Age: 43 years (18-87)
- Gender: 24 male; 36 females
- Body mass; 83.9 kg (47-118kg)
- Height: 166.2 cm (124-193 cm)
- 60 healthy volunteers without shoulder pathology
- Data Collection
- Internal Rotation Behind-the-Back angle – The patient reaches behind their back to the highest point possible along their midline. Using a standard goniometer, the angle between the ulna and a line representing gravity (perpendicular to the floor) was measured by two independent evaluators, blinded to the results of the other’s measurement. (Figure 1)
Figure 1. Internal Rotation Behind-the-back angle measured with a goniometer
- Data Analysis
- Paired student t test, Pearson correlation coefficient, and weighted Cohen kappa was performed to evaluate inter- and intra-observer reliability.
Results.
- Internal rotation behind the back angle
- Mean: 95°
- Range: 50° – 125°
- 95% Confidence Interval: 59° – 131°
- Interobserver Reliability
- Student t test: 0.6°(95% Confidence Interval: 0.1° – 1.3°)
- Pearson correlation coefficient: 0.98
- Kappa coefficient:0.88
- Intraobserver Reliability
- Student t test: 0.6°(95% Confidence Interval: -0.8° – 1.8°)
- Pearson correlation coefficient: 0.92
- Kappa coefficient: 0.77
Clinical Relevance. Internal rotation behind-the-back angle is easy to measure, is reproducible, and provides objective data to measure meaningful, functional progress of active shoulder mobility.
