Background Various measurement methods have been defined to assess the alignment of the lower extremities. The Q-angle measurement is reported to be associated with knee injury and patellofemoral dysfunction. The Q-angle has been assessed using radiography scans, goniometer and photogrammetry methods in supine and standing positions. The radiography method is accepted to be the most accurate and valid measurement technique in measurement the Q-angle. But as a result of being expensive and time-consuming, this invasive method is not mostly preferred in research and clinics. The goniometric measurement of Q-angle is practical because it is simple, requires inexpensive equipment (only a goniometer), and can be applied in a short time. Photogrammetry measurement technique is also an advantageous method for reducing measurement errors caused by goniometers and reduction of investigator errors.
Objectives The aim of the present study, was to compare the clinical assessment of the Q-angle (goniometric and photogrammetric measurement methods) to a radiological assessment using radiograph (criterion validity) in patients with varus knee osteoarthritis.
Methods The study group consisted of 15 (median age 68.6±11.9 years) patients with unilateral and bilateral varus knee osteoarthritis. Q-angle measurements were assessed on both lower extremities with three different goniometric methods (goniometric measurement method in standing position with quadriceps muscle relaxed; goniometric measurement method in supine position with quadriceps muscle relaxed; and contracted) using a 360° universal goniometer. After the goniometric measurements, photographs were taken with quadriceps muscle relaxed in standing position. For radiographic assessment, we used patients' lower extremity scanograms, which had been taken to determine the diagnosis and treatment from the Computer Patient Archiving System database.
Results There was a good correlation between the radiographic assessment and photogrammetric measurement (r=0.623, p<0.001). Also a good correlation was observed between radiographic assessment and goniometric measurement (in standing position with quadriceps muscle relaxed; in supine position with quadriceps muscle relaxed; and contracted) (r=0.676, p<0.001, r=0.616, p<0.001, r=0.676, p<0.001, respectively).
Conclusions According to our result, the photogrammetric measurement and the goniometric measurement appear to be valid alternatives to the radiographic measurement for determining the Q-angle. These alternative measures might be used by clinicians and researchers to measure the Q-angle of patients with varus knee osteoarthritis in orthopaedic clinics.
Disclosure of Interest None declared