## 4 Discussion
This may be because there is the constant stretching effect over the patellar tendon during squatting and kneeling, which are common activities in India, Japan, China, and the Middle East [1]. This trend is opposite to that reported in our study. However, the population considered in our study consisted of Asians who were old-age patients and found it less comfortable to perform such activities. Therefore, the obtained results are reasonable. Our results indicate that the TL/PL ratio is higher in females than in males. The TL/PL ratios in females and males were \(0.94\pm 0.14\) and \(0.87\pm 0.14\), respectively, in our study. These results show good agreement within other studies that found higher TL/PL ratio for females [5; 6; 8; 18]. However, some other studies have demonstrated the opposite trend [32]. The mean TL/PL ratio for 100 males and females each were found to be 1.41 and 1.28 in the population of South India [32]. No significant differences in TL/PL ratios between males and females were reported in a previous study [18]. Likewise, [PERSON] and [PERSON] [33] and [PERSON], et al. [34] found the ratio to be independent of gender. However, a difference in TL/PL ratio between the genders was found in our study. Such a trend has also been found in other studies [5; 8]. The TL/PL ratio is a reliable and general index to estimate the height of the patella. We can see that different studies show inconsistent results in the gender difference of TL/PL. In this study, a much wider Korean population was examined. In addition, our results indicate a slightly skewed distribution that shows a mean ratio of 0.92. Therefore, we defined patellar alta and baja with the 2 SD method and the extreme 2.5% method. Two SD at the other end, where the curve is more moderate, include more than the extreme 2.5% [5]. These results can explain why in previous studies patellar alta appeared more common than patellar baja [5]. Our results show slightly skewed distribution but there was no difference between the 2 SD method and extreme 2.5% method. It showed a slightly skewed distribution but there is no problem with investigating alta and baja using the 2 SD method. In the extreme 2.5% method, there are 34 (2.39%) in alta and 35 (2.46%) in baja, in the 2 SD method, there are 27 (1.90%) in alta and 30 (2.11%) in baja. However, in [PERSON] and [PERSON]'s previous article, 95% of the population fell within the ratios of \(1.00\pm 20\%\); thus, defining the normal limits [8]. If the identical numeric criteria of \(1.00\pm 20\%\) were applied to our population, 27 knees of 1423 patients (1.9%) would be determined as patellar alta and 282 (19.8%) patellar baja. We also recognize that our population of patients with painful knees is biased, but it is fairly likely to represent a large group of patients undergoing clinical MRI knee examinations. Our results are replicated by other groups to ensure the transferability of our conclusions to different populations. The TL/PL ratio is one of the indices of the patellar position in the patellofemoral joint. The Q-angle is also an index of patellofemoral stability in males and females of identical height [35]. The patella articulates with the trochlear at high degrees of flexion [35]. Patellar alta may contribute to contact friction between the posterior region of the patellar tendon and femoral condyles before it articulates with the trochlear. Its gender dimorphism may help explain the difference in patellfoemoral biomechanics. The gender dimorphism of the Insall-Salvati ratio of the patellar tendon may help explain the difference in prevalence of tendinopathy between the genders and the regional distribution of forces in the patellar tendon [35]. We studied a wider group without symptoms, and disregarded history and other MRI findings. In addition, we did not make an attempt to determine if patients were at the extremes of the TL/PL ratios with patellfoemoral symptoms or patellfoemoral MRI abnormalities.