Designing of a new radiologic model for chondromalacia patellae according to MRI findings: the novel role of tibial anatomy

Abstract

Objectives: Magnetic resonance imaging (MRI), is a non-invasive highly sensitive tool for diagnosing chondromalacia patellae in the early stages. Many studies have evaluated patellar and trochlear morphology with different radiologic indices. We aimed to assess the discriminative power of tibial, patellar, and femoral indices in MRI for chondromalacia patellae.

Methods: 100 cases of chondromalacia, as well as 100 age-matched controls among the patients who underwent knee MRI between February 2017 and March 2019, were included. The standard protocol of knee MRI was applied and the diagnosis of chondromalacia was made on MRI findings. Chondromalacia subjects were also classified as grade 1 to 4 according to the Modified Outerbridge’s MRI grading system. We measured 25 MRI parameters in the knee and adjacent structures to determine the relation between chondromalacia patellae and anatomical MRI parameters.

Results: Tibial slope, trochlear depth, lateral trochlear inclination, and lateral patellar tilt angle had significant correlation with chondromalacia. Any increase in medial tibial slope and trochlear depth could decrease the probability of the disease (Odds ratio 0.85, 0.06; 95% CI: 0.73-0.98, 0.02-0.17, respectively), while we observed opposite results for lateral trochlear inclination and lateral patellar tilt angle (Odds ratio 1.15, 1.13; 95% CI: 1.03.1.30- 1.02-1.26, respectively). We also designed a model for the severity of disease by using the patellar height index (relative odds ratio: 75.9).

Conclusions: The result of this study shows the novelty role of tibial anatomy in developing chondromalacia. We also concluded that patellar height may be an important factor in defining disease severity.