Reliability of Using a Handheld Tablet and Application to Measure Lower-Extremity Alignment Angles.

CONTEXT Landing kinematics have been identified as a risk factor for knee injury. Detecting atypical kinematics in clinical settings is important for identifying individuals at risk for these injuries. OBJECTIVE To determine the reliability of a handheld tablet and application (app) for measuring lower-extremity kinematics during drop vertical-jump landings. DESIGN Measurement reliability. SETTING Laboratory. PARTICIPANTS 23 healthy young adults with no lower-extremity injuries and no contraindications for jumping and landing. INTERVENTION Subjects performed 6 drop vertical jumps that were captured with an iPad2 and analyzed with a KinesioCapture app by 2 novice and 2 experienced raters. Three trials each were captured in the frontal and sagittal planes. MAIN OUTCOME MEASURES Frontal-plane projection angles, knee flexion, and hip flexion at initial contact and maximum knee flexion were measured. ICC and SEM were calculated to determine intertrial and interrater reliability. One-way ANOVAs were used to examine differences between the measured angles of the raters. RESULTS Average intertrial reliability ranged from .71 to .98 for novice raters and .77 to .99 for experienced raters. SEMs were 2.3-4.3° for novice raters and 1.6-3.9° for experienced raters. Interrater ICC2,1 was.39-.98 for the novice raters and .69-.93 for the experienced raters. SEMs were smallest with the experiences raters, all less than 1.5°. CONCLUSION A handheld tablet and app is promising for evaluating landing kinematics and identifying individuals at risk for knee injury in a clinical setting. Intertrial reliability is good to excellent when using average trial measures. Interrater reliability is fair to excellent depending on experience level. Multiple trials should be assessed by a single rater when assessing lower-extremity mechanics with a handheld tablet and app, and results may vary with experience level or training.