Abstract
Objective: The current study was designed to evaluate the validity and reliability of finding the center of the patella utilizing manual palpation versus a specialized tool. Methods: The researchers positioned a cadaver in supine position with hips in minimal external rotation and knees in relative full extension. The researchers measured each patella with a caliper and placed a dot at the center of each patella with a fluorescent pen. The examiners rolled a die to determine which method ("The Quad Rule" or manual palpation) they would utilize. The researcher measured the distance from the found center of the patella to the fluorescent dot. The process was repeated on the opposite knee with the second method. After the data were collected the researchers drilled a hole through the fluorescent dot and the patellae were dissected. The data were adjusted to correct for discrepancies between the drilled hole and the dissected center of the patella. Results: Nineteen subjects participated day one (14 physical therapy students and 5 physical therapists) and 13 subjects on day two (13 PT students). The entire sample was on average 7.53mm closer to the actual center vertically when using the quad rule (students: 9.42mm; PTs: 2.25mm) as compared to the manual palpation technique. The entire sample was on average 7.60mm closer horizontally when using manual palpation (students: 8.66mm; PTs: 4.63mm). Significant differences were noted in t-Tests between the device and palpation, and between S/I and M/L measurements within the same method. Conclusion: Utilizing a measuring device to palpate the center of the patella may be a viable alternative to manual palpation. Further research is necessary to validate and rule out possible systematic errors that occurred due to the position of the cadaver and plasticity of the embalmed tissue.