Elsevier

Journal of Shoulder and Elbow Surgery

Volume 11, Issue 1, January–February 2002, Pages 40-42
Journal of Shoulder and Elbow Surgery

Original Articles
Interobserver and intraobserver reliability of the measurement of shoulder internal rotation by vertebral level

https://doi.org/10.1067/mse.2002.119853Get rights and content

Abstract

Internal rotation is commonly measured as the vertebral level reached by the fully extended thumb. The purpose of this study was to evaluate interobserver and intraobserver reliability with the use of this method. Three male subjects were used for internal rotation measurement. Eleven orthopaedic surgeons and 2 physical therapists served as examiners. Each subject had a radiographic marker placed at a random vertebral level, and the subject's extended thumb was placed at this marker. All examiners then independently measured internal rotation based on vertebral level. To assess intraobserver reliability, this process was repeated twice. After all measurements were completed, an anterior-posterior radiograph of each subject was obtained to define the vertebral level of the marker. This process was repeated 2 additional times with the marker and subject's thumb positioned at different levels than in the previous examination. Intraclass correlation coefficients were calculated to determine reliability. Results demonstrated poor interobserver reliability and reasonable intraobserver reliability. The mean clinical measurement deviated from the mean actual measurement by 1 vertebral level. Despite being the standard method in which shoulder internal rotation is measured, measurement of internal rotation by vertebral level is not readily reproducible between observers. (J Shoulder Elbow Surg 2002;11:40-2.)

Introduction

Thorough examination of the shoulder joint includes accurate documentation of range of motion. The American Shoulder and Elbow Surgeons recommend documenting active and passive total elevation, active and passive external rotation with the arm at the side, active and passive external rotation with the arm positioned at 90° abduction, and active or passive internal rotation of the shoulder.6 Internal rotation of the shoulder is commonly measured by assessing the point reached on the back by the tip of the extended thumb.7, 14 This method of determining functional internal rotation of the shoulder has been criticized because it does not measure pure internal rotation of the glenohumeral joint; it is affected by concurrent pathologic conditions in the elbow, wrist, or thumb, and it may not be easy to determine bony landmarks in the spine.7, 9, 10

Although measurement of internal rotation by vertebral level is commonly used, little investigation into the reliability of this measurement technique has been performed.11 The purpose of this study is to determine the interobserver and intraobserver reliability of measuring shoulder internal rotation by vertebral level reached by the extended thumb. In addition, the accuracy of these clinical measurements is assessed by a comparison with the actual vertebral level reached as determined radiographically.

Section snippets

Materials and methods

Three volunteers acted as subjects for internal rotation measurement. Their mean age was 28 years (range, 26-29 years). All 3 subjects were men. None of the subjects' shoulders was abnormal. One subject had a history of shoulder subluxation 13 years previously that was treated successfully with rehabilitation. In addition, all 3 subjects were of appropriate weight for height, yielding easily palpable bony landmarks.

Eleven orthopaedic surgeons and 2 physical therapists served as examiners. The

Results

Radiographs demonstrated that internal rotation ranging from T4 to L5 was tested. Interobserver intraclass correlation coefficients for each of 3 rounds of measurements were 0.12, 0.27, and 0.25, respectively. An intraclass correlation coefficient of less than 0.4 indicates poor reliability. Thus interobserver reliability was found to be poor. The mean error for measurement of each of the 3 rounds when the clinical measurements were compared with the radiographic values was 1.15, 1.02, and

Discussion

Internal rotation has been a problematic parameter of measurement in examination of the shoulder. Concerns about contributions from adjacent joints (ie, scapulothoracic and elbow) and difficulty of palpating bony landmarks have been raised with regard to the measurement of shoulder internal rotation by vertebral body reached.7, 10 Although goniometric measurements have been reported widely for measuring reliability of other parameters of shoulder mobility, their use in measuring internal

References (16)

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  • Using machine learning to predict internal rotation after anatomic and reverse total shoulder arthroplasty

    2022, Journal of Shoulder and Elbow Surgery
    Citation Excerpt :

    They reported significant improvements in performing those functional IR activities despite patients not achieving significant improvement in IR physical measurements. It is important to note that Southard et al37 did not measure IR by the most common vertebral level method because of concerns of measurement error and reliability, as has been previously reported by and Edwards et al and Rojas et al.9,33 Instead, Southard et al37 proposed a new technique that quantifies IR by one of 3 types (type 1: could not reach behind back, type 2: able to reach to waist level, and type 3: able to reach to a minimum waist level in an uninterrupted fashion). Unfortunately, their proposed method has low resolution, having only 3 measurement scores, which is the most likely reason for not observing significant changes in IR after rTSA.

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Reprint requests: Richard V. Baratta, PhD, Louisiana State University Health Sciences Center, Department of Orthopaedic Surgery, 2025 Gravier St, Suite 400, New Orleans, LA 70112 (E-mail: [email protected]).

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