Results

The demographic characteristics of the study population were comparable between male participants and female participants. The mean age of male participants was 35.4 ± 9.0 years, and that of female participants was 35.5 ± 8.6 years, indicating a similar age distribution across both groups. Male participants had a slightly higher mean height (164.8 ± 8.2 cm) compared to female participants (163.7 ± 9.2 cm). Similarly, the mean body weight was higher in male participants (66.6 ± 8.5 kg) than in female participants (63.3 ± 9.1 kg), as shown in Table 1.

Variable | Male (Mean ± SD) n=300 | Female (Mean ± SD) n=300
Age (years) | 35.4 ± 9.0 | 35.5 ± 8.6
Height (cm) | 164.8 ± 8.2 | 163.7 ± 9.2
Weight (kg) | 66.6 ± 8.5 | 63.3 ± 9.1

The comparison of the Q-angle between male participants and female participants revealed a statistically significant difference, with female participants demonstrating higher Q-angle values (16.53 ± 5.22) compared to male participants (13.85 ± 5.32°). The mean difference was -2.96° (95% CI: -3.28 to -2.09), which was highly significant (p < 0.001), and the strength of association (Point-Biserial correlation) was 0.25 (medium effect size). This indicates a clear gender-based variation in the Q-angle.

In contrast, the ICD does not show a statistically significant difference between male participants (9.39 ± 1.33 cm) and female participants (9.26 ± 1.36 cm). While male participants showed slightly higher values, the mean difference of 0.27 cm (95% CI: -0.02 to 0.28) was not statistically significant (p = 0.083), and the strength of association (Point-Biserial correlation) was 0.05 (little/no association), as shown in Table 2.

Variable | Parameter | Total | Gender | Difference (95% CI) | Significance | Test Statistic
Male | Female
Q-Angle (°) | Mean ± SD | 15.19 ± 2.52 | 13.85 ± 5.32 | 16.53 ± 5.22 | -2.69 (-3.28 to -2.09) | p = <0.001 | W=65298.000
ICD (cm) | Mean ± SD | 9.32 ± 1.33 | 9.39 ± 1.33 | 9.26 ± 1.36 | 0.13 (-0.02 to 0.28) | p = 0.083 | t=1.736

In male participants, the mean Q-angle was slightly higher on the right side (14.48 ± 8.21°) compared to the left (13.92 ± 8.34°), and the difference was statistically significant (p = 0.029). Similarly, in female participants, the right side (16.52 ± 8.41°) showed marginally higher values than the left (16.02 ± 8.66°), and the difference was significant (p = 0.034). This shows that the Q-angle demonstrates significant bilateral asymmetry in both male and female genders. Numerical differences show stance dominance, representing that the pull of quadriceps muscles affects the knee alignment on both sides.

The ICD, among male participants, the ICD was 9.27 ± 1.36 cm (right) and 9.25 ± 1.34 cm (left), with no significant difference (p = 0.970). Among female participants, ICD values were 9.27 ± 1.36 cm (right) and 9.32 ± 1.28 cm (left), also showing no significant difference (p = 0.362), as shown in Table 3. This shows that the ICD remains highly consistent between sides in both genders and indicates symmetrical condylar alignment and load distribution.

Variable | Right | Left | p-value | Test Statistic | Significant | Test
Q-Angle (°) (Male) | 14.48 ± 8.21 | 13.92 ± 8.34 | 0.029 | z= -2.18 | Significant | Wilcoxon signed-rank test
Q-Angle (°) (Female) | 16.52 ± 8.41 | 16.02 ± 8.66 | 0.034 | z= -2.12 | Significant
ICD (Male) | 9.27 ± 1.36 | 9.25 ± 1.34 | 0.970 | t= 0.04 | Not Significant | Paired t-test
ICD (Female) | 9.36 ± 1.30 | 9.32 ± 1.28 | 0.379 | t= -0.88 | Not Significant

Spearman’s correlation analysis demonstrated a very weak negative correlation between the Q-angle and ICD (ρ = -0.04) in overall male and female participants. However, this relationship was not statistically significant (p = 0.223). The 95% confidence interval (-0.09 to 0.02) includes zero, further confirming the absence of a meaningful association between the two. These findings indicate that changes in the ICD do not significantly influence the Q-angle in the studied population, as shown in Table 4 and Figure 3.

Correlation | Spearman Correlation Coefficient | p-Value
Q-Angle (°) vs ICD | -0.04 | 0.223

Figure 3: The scatterplot depicts correlation between ICD and Q-angle (°). Individual points represent individual cases. The blue trendline represents the general trend of correlation between the two variables.Q-angle: Quadriceps angle; ICD: bicondylar distance

In male participants, Spearman correlation analysis demonstrated a very weak positive correlation between the ICD and Q-angle (ρ = 0.05), which was not statistically significant (p = 0.225). Similarly, female participants showed a very weak negative correlation between the Q-angle and ICD (ρ = -0.05), which is not statistically significant, as shown in Table 5 and Figures 4a, 4b. This indicates that the ICD was not a meaningful determinant of Q angle in the studied population.

Figure 4: a) Scatter plot illustrating the relationship between quadriceps (Q) angle and bicondylar distance (ICD) in male participants (n = 300). b) Scatter plot illustrating the relationship between the quadriceps (Q) angle and ICD in female participants (n = 300).Each black dot represents one participant. The solid line represents the fitted linear regression line, while the shaded grey region denotes the 95% confidence interval of the regression estimate.

Correlation | Spearman Correlation Coefficient (ρ) | p-Value
Q-Angle (°) vs ICD in male participants | 0.05 | 0.225
Q-Angle (°) vs ICD in female participants | -0.05 | 0.257