Reliability and Validity for Measuring Active Hip Rotation with the Clinometer Smartphone Application™

Accurate range of motion (ROM) assessment is an essential component of clinical practice to identify underlying deficits at the hip joint. Hip joint active ROM has been measured by goniometric methods in the clinical setting. More recently, the Clinometer Smartphone Application has gained attention for ROM measures.  However, minimal research has been identified for the use of the Clinometer Smartphone Application™ for hip ROM. Therefore, the purpose of this study was to determine intrarater and interrater reliability of the Clinometer Smartphone Application™ as well as establishing its validity for active hip internal rotation (IR) and external rotation (ER).
A concurrent test-retest reliability study was conducted using a convenience sample at three different sites. This study included 46 males and 30 females (n = 76) with an average age of 23.93 (5.37) years.  Five clinicians measured each participant’s active prone hip rotation at three different sites. Three trials were measured with the goniometer and with the Clinometer Smartphone Application™. Intrarater reliability was assessed within one week for the five clinicians. Interrater reliability was assessed between three clinicians located at the same site.
The intrarater reliability of goniometer was moderate to excellent (ICC > .73 - .96) for hip IR and moderate to good (ICC > .76 - .89) for ER. Similarly, smartphone intrarater reliability was good to excellent for IR (ICC > .81 - .96) and ER (ICC > .77 - .90). The validity of the Clinometer Smartphone Application™ when compared to the goniometer and had a very strong relationship for IR (r = .94 - .96) and ER (r = .84 - .89).
The results of this study suggest this application may be a valid and reliable alternative to the goniometer for clinicians when measuring active hip rotation in clinical practice.