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Background: Insall-Salvati index (ISI) is widely used to evaluate patella position, the specific relationship between quadriceps patellar tendon angle (QPA) and patellofemoral measurements remains unclear. Understanding this relationship could provide valuable insights into diagnosing and treating knee pain, instability, and patellofemoral pathologies more effectively. In this study, we aimed to assess whether there was a significant difference between the patients with patella alta and baja in terms of many patellofemoral measurements and pathologies. Furthermore, we evaluated a newly described QPA., Methods: A retrospective cross-sectional study including 446 patients who underwent knee magnetic resonance imaging (MRI) between 2019 and 2021 in Basaksehir City Hospital was conducted. Two hundred and five patients were divided into two groups according to their ISI (ISI >1.3 and ISI <0.8). The patellar tendon length, patellar height, patella angle, lateral patellar tilt angle (LPTA), patella-patellar tendon angle (PPTA), QPA, medial and lateral trochlear inclination, patella angle, trochlear sulcus angle (TSA), trochlear groove depth (TGD), medial and lateral trochlea length (LT), medial trochlea length (MT) and LT ratio and tibial tubercle-trochlear groove distance, fat-pad edema, chondromalacia and effusion were evaluated. Whether the measurement or presence of pathology differed significantly according to ISI were investigated. The difference between two arithmetic means were analyzed with T -test. The Mann-Whitney U test were used for assessing the difference between two independent groups and to determine difference or equality between groups., Results: When the groups with ISI >1.3 and <0.8 were compared with each other in terms of measurements, patellar tendon length, tibial tubercle-trochlear groove distance, LPTA, PPTA, QPA were found to be significantly higher in the group with ISI >1.3 (P<0.05). Patellar height and TGD were significantly greater in the group with ISI <0.8 (P<0.001, P=0.007). Patellar tendon length, patellar tendon height, tibial tubercle-trochlear groove distance, patella angle, TGD, MT and LT, PPTA, QPA, medial trochlear inclination values and frequency of fat-pad edema were significantly higher in men (P<0.001). The ISI, TSA and frequency of chondromalacia was found to be significantly higher in women (P<0.001)., Conclusions: Major angles such as LPTA, PPTA, patellar tendon length, tibial tubercle-trochlear groove distance and QPA were increased in the group with patella alta. The patients with patella baja have higher patellar height and TGD., Competing Interests: Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-23-1722/coif). The authors have no conflicts of interest to declare., (2024 AME Publishing Company. All rights reserved.)

Background: The newly defined angle, quadriceps-patella angle (QPA), reflects the combined force transmitted to the patella by the quadriceps muscles and patellar tendon. An increase in QPA may correlate with an increased force on the patella, which is significant in diagnosing patellofemoral instability and pain syndrome. In our study, we examined how various angles and pathologies vary depending on lateral patellar tilt angle (LPTA). QPA and patellar malalignment was investigated. Thus, the importance of understanding patellar malalignment and the research gap., Methods: Three hundred and fifty patients who underwent knee magnetic resonance imaging (MRI) examinations were included. The cross-sectional study conducted retrospectively between the years of 2018-2020 in a tertiary care outpatient clinic. Shapiro-Wilk normality, Chi-square, Mann-Whitney- U , Spearman correlation and receiver operating characteristic (ROC) curve analysis, statistical tests used for analysis. The patellar tendon length, patellar height, tibial tubercle-trochlear groove distance (TT-TG), patella angle, trochlear sulcus angle, trochlear groove depth (TGD), medial trochlea length (MT), lateral trochlea length (LT), medial trochlear/lateral trochlear length ratio (MT/LT), LPTA, patella-patellar tendon angle (PPTA), QPA, Insall-Salvati index (ISI), medial trochlear inclination (MTI), lateral trochlear inclination (LTI) were among these measurements. In addition, we aim to reveal whether there is a significant relationship between two important angles LPTA and QPA. Whether there is a significant increase in the development of chondromalacia for the patient group with LPTA >5°. We examined how the frequency of chondromalacia changes in the patient group with LPTA >5°., Results: Two hundred and seventy seven patients included in the study and many measurements were performed on MRI. Fad-pad edema was found to be significantly higher in the group with LPTA <5° (P=0.046). TT-TG distance was significantly higher, TGD and MT were significantly lower in patients with higher LPTA (P=0.001, P=0.002 and P=0.017, respectively). A low level of significant positive correlation was found between QPA and patellar tendon length. There is no significant difference between QPA and PPTA angles between the groups with LPTA <5° and >5° (P=0.503, P=0.188). In the ROC analysis performed to determine the cut-off value, the LPTA value ≤14.2° which significantly predicted the presence of fad-pad edema, had the highest sensitivity and specificity [sensitivity: 76.71%, specificity: 39.90%, area under the curve (AUC): 0.588, P=0.024]., Conclusions: QPA is independent from many angles of the knee and does not change significantly. As the patellar tendon length increases, QPA angle also increases. In patients with abnormal LPTA, the frequency of TT-TG distance and chondromalacia increased, while TGD and MT decreased. Patients with a low LPTA can be more carefully examined for chondromalacia and fad-pad edema in clinical and MRI examination., Competing Interests: Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-23-1592/coif). The authors have no conflicts of interest to declare., (2024 Quantitative Imaging in Medicine and Surgery. All rights reserved.)