A novel assessment of the differences in various measurements in patients with patella alta and baja: a retrospective cross-sectional study.

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 -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.