The assessment of mobility is an integral component of a physical examination. The examination of joint integrity and mobility is necessary in order to select appropriate physical therapy interventions.1
Recognizing impairments in joint mobility may assist clinicians in making diagnoses, measuring improvements or deteriorations in mobility, and in determining functional limitations. Therefore, it is essential for clinicians to have reliable and valid measurement instruments in order to objectively monitor disease progression, outcomes, and mobility impairments.
The examination of shoulder mobility may be accomplished using a number of instruments including: visual observation, goniometry, linear measures, and inclinometry.2
The method and type of assessment will vary among clinicians and institutions based on factors such as time, educational inclination of the clinician, availability of equipment, and the specific movement or tissue being assessed. Goniometry has been used widely due to its portability and low cost.3,4
However, a limitation of goniometry is that it requires the clinician to use both hands, making stabilization of the extremity more difficult, and thus increasing the risk of error in reading the instrument.3
Inclinometry is another practical alternative that incorporates the use of constant gravity as a reference point to assess joint mobility.4–6
Digital inclinometers are portable, lightweight, and require training similar to that of goniometry. However, a disadvantage of digital inclinometry may lie in the fact that it is more costly than conventional goniometers, and requires the examiner to establish the zero point of the digital inclinometer accurately and consistently prior to use in order to minimize the risk of measurement errors.
A recent literature review of shoulder mobility measurements identified comparable use of goniometry and inclinometry among published research investigations; however, no study existed to compare the concurrent validity of goniometry and digital inclinometry.7
The paucity of research on the interchangeability of these two instruments presents a question as to whether clinicians or researchers can translate findings from a study that used a different instrument with confidence. Specifically, data such as normative values or change scores established with inclinometry may not be valid to a clinician using goniometry and vice versa.
Given the lack of available research investigating the concurrent validity of goniometric and inclinometric measurements of shoulder mobility, further investigation is essential in order to provide clinicians and researchers with the necessary information needed to make clinical decisions regarding their interchangeability. Therefore, the primary purpose of this study was to investigate the concurrent validity of digital inclinometry and goniometry for measuring active shoulder abduction, flexion, internal and external rotation. Additionally, we sought to investigate the intrarater reliability for both instruments.