Abstract
Objective: The current study was designed to evaluate the validity and reliability of finding the quadriceps angle (Q-angle) utilizing manual palpation versus a specialized tool. Methods: A male and female subject volunteered to have their knee measured as part of this study. Doctor of Physical Therapy students and faculty were recruited to measure the right knee of each of these to subjects utilizing one of two methods using: “The Quad Rule” device or manual palpation. These participants were randomly assigned to a method group by blocked randomization. On the day of data collection, each participant was given instruction for their assigned method and practiced their measuring skills on each other before measuring each of the subjects. During measurement, each of the test subjects was positioned in supine position with their right knee in full extension and neutral internal and external rotation. The participants then took 3 consecutive measurements utilizing their assigned method on the right knee of both the male and female subject. Each measurement and the average of their measurements were recorded on a data sheet. On a separate day, both the male and female subject had an X-Ray image taken of their right knee in the same position and the Q-angle was measured utilizing the image. Measurements from each sample group were compared to this “gold standard” measurement. Results: Forty One participants volunteered for this study (37 physical therapy students and 4 licensed physical therapists) with 21 of the participants assigned to the manual palpation group and 20 participants assigned to the device group. Of the 37 students, 12 were 2nd year physical therapy students and 25 were 1st year physical therapy students. The radiographically measured Q-angle was determined to be 13 degrees on the male subject and 17 degrees on the female subject. For the entire sample, when comparing mean differences between device and palpation methods using independent T-tests no significant differences were noted. Measurement of the male subject did not show a significant mean difference vs. the X-ray measurement for either group (device: +1.52 degrees, palpation: +1.58 degrees). When measuring the female subject, there was also no significant statistical difference noted, although the device method showed a clear overestimation compared to that of the palpation method (device: +2.1 degrees, palpation: +.91 degrees). Additional T-Tests found that a significant difference in accuracy and mean measurement exists when comparing 1st year students vs. 2nd year students and physical therapists which indicate better results with additional experience level among all methods. Conclusion: For an entry level clinician with palpation experience, utilizing a measuring device to measure the Q-angle may be a viable alternative to manual palpation. However, with increased time required for measurement using the device and no significant difference noted in accuracy when compared to manual palpation, it appears to have little clinical value at this time. Future research with a larger sample of physical therapists is needed to determine the impact of greater experience level on the accuracy and reliability of the device. Modifications to the device could also be explored with the intention of improving its ease of use and accommodation of anatomical differences at the knee.