Relationship between Q angle and clinical findings, radiological stage, and ultrasonographic evaluation in female patients with knee osteoartritis

Aim: The aim of this study is to evaluate the relationship between Quadriceps (Q) angle applied for the alignment of the lower extremity and demographic features, clinical findings, severity of radiological findings, tibiofemoral cartilage thickness and semiquantitative grading measured by ultrasonography in female patients with symptomatic primary knee osteoarthritis (OA). Materials and Methods: The study included 80 patients (160 knees in total) with bilateral knee OA based on American Society of Rheumatology (ACR) criteria, meeting the inclusion and exclusion criteria. The demographic characteristics, concomitant diseases, and duration of the symptoms were recorded. Body mass indexes (BMI) were calculated by measuring the height and weight of the patients. The Visual Analogue Scale (VAS) was used for assessment of pain. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was used to assess pain, stiffness and physical functions. Right femur length and hip width were measured. Q-angle measurements were made according to the standardized protocol created with a long-arm goniometer and a bed-mounted foot positioning instrument both of which were specially designed for this study. The radiological Kellgren-Lawrence (K-L) staging scale was applied to evaluate the knee x-rays of the patients. In the ultrasonographic examination of the patients, distal femoral cartilage thickness and semiquantitative cartilage grading were measured. The relationship between these variables and Q angle was examined. In the correlation study, the relationship was investigated bilaterally both for the decrease (Q angle <16°) and for the increase (Q angle >12°) of the Q-angle from normal range values (12-16°). Results: The mean age of the patients included in the study was 59.2±10.4 years. According to the K-L radiological staging of the 160 knees evaluated in the study; It was determined that 40% (n=64) were stage 1, 18% (n=29) were stage 2, 34% (n=54) were stage 3, and 8% (n=13) were stage 4. According to semiquantitative ultrasonographic cartilage grading of these knees, it was determined that 34% (n=54) were grade 1, 34.5% (n=55) were grade 2a, 21.2% (n=34) were grade 3, and 17% (n=27) were grade 4. The mean Q angle was obtained as 16.6±4.4 ° on the right and 16.5±4.5° on the left, when comparing the values, no significant difference was found between the two sides. There was not statistically significant relationship between Q angle and demographic features, range of motion, VAS, WOMAC, duration of symptoms and distal femoral cartilage thickness values of the patients (p >0.05). In the knees where the Q angle is less than the upper limit of the normal (Q angle <16°), while there was a negative (P <0.05; r = -0.250) relationship between the Q angle and the KL radiological stage, a significant relation (p <0.01; r =0.444) was detected in the same direction in the knees (Q angle >12°) where the Q angle was more than the lower limit of normal. Similarly, while a significant negative correlation (p <0.05; r = -0.218) was found between the Q angle and the semiquantitative ultrasonography scores of the femoral cartilage in the knees with Q angle <16°, in knees with Q angle > 12°, a significant relation was found in the same direction (p <0.01; r =0.498). In the knees with an Q angle <16°, while the mean Q angle was determined as 12.8±1.6° and 11.1±4.6°, respectively, in those with early stage (1 and 2) and advanced stage (3 and 4) radiological findings, these values were 16.5±3.6° and 19±2.8° in the knees with Q angle >12°, respectively. In terms of ultrasonographic grading in knees with a Q angle <16°, while the mean Q angle was found to be 13.0±1.8° in the knees with degree 1 and 2a (early), it was 10.5±3.6° with degree 2b and 3 (advanced). In knees with a Q angle >12° these values were 16.7±3.5° and 18.9±2.6°. Whether radiologically (Q angle <16°, p <0.05; Q angle >12°, p <0.01) or ultrasonographically (Q angle <16 °, p <0.01; Q angle >12 °, p <0.01) Q angle in knees in the early stage was found close to physiological values. In addition, a significant and strong correlation (p <0.01; r =0.800) was found between the semiquantitative ultrasonography scores of the femoral cartilage and the K-L radiological stage. Moreover, it was determined that there was a significant relationship between K-L radiological stage and ultrasonographic degree distribution, and the level of cohesion of this relationship was between the Contingency Coefficient 65 and Spearman Correlation at 75 levels. Conclusion: Our data suggest that there was a significant relationship between the deviation (increase or decrease) of Q angle from physiological values and the progression of radiological and articular cartilage semiquantitative findings in female patients with knee OA. In addition, these findings highlight the importance of Q angle measurement in the early diagnosis and follow-up of patients with knee OA. Despite these findings, it is recommended to plan well-standardized clinical trials with a higher number of cases related to the Q angle.