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Reliability of the quadriceps angle measurement
C C Greene1, T B Edwards, M R Wade
1Department of Orthopedic Surgery, Louisiana State University Health Sciences Center, New Orleans, USA.
The American Journal of Knee Surgery
|June 13, 2001
Summary
The quadriceps angle (Q-angle) measurement shows poor reliability among observers and within the same observer. Clinical Q-angle measurements also poorly correlate with radiographic findings.
Area of Science:
- Orthopedics
- Biomechanics
- Medical Imaging
Background:
- The quadriceps angle (Q-angle) is a common clinical measurement.
- It is used to assess patellofemoral alignment and diagnose related pathologies.
- However, the reliability of Q-angle measurement has not been extensively studied.
Purpose of the Study:
- To evaluate the interobserver and intraobserver reliability of the Q-angle measurement.
- To compare the reliability of clinically derived Q-angles with radiographically derived measurements.
Main Methods:
- 25 individuals measured the Q-angle of 24 other participants to assess interobserver reliability.
- 3 observers re-measured 13 participants twice to assess intraobserver reliability.
- Intraclass correlation coefficients (ICCs) were used for reliability analysis.
Main Results:
- Interobserver reliability ICCs ranged from 0.17-0.29.
- Intraobserver reliability ICCs ranged from 0.14-0.37.
- Correlation between clinical and radiographic Q-angles showed ICCs ranging from 0.13-0.32.
Conclusions:
- The study demonstrates poor interobserver and intraobserver reliability for Q-angle measurements.
- There is a poor correlation between clinically and radiographically derived Q-angle measurements.
- These findings question the clinical utility of the Q-angle for assessing patellofemoral alignment.
