Objective: To determine variation in structure and alignment of the knee between patients with proximal patellar tendinitis (PT) and a control group, with emphasis on the patellofemoral joint on MRI.

Materials & Methods: Case group included retrospective inclusion of 25 patients with diagnosed PT on MRI. Control group included 50 patients with no radiological or clinical evidence of PT and underwent MRI of the Knee. Physically active patients and controls were matched for age and gender.

Two radiologists evaluated Knee MRIs assessing parameters such as patellar & trochlear morphology, patellofemoral & tibiofemoral alignment. Student’s t test was used to find out the differences in parameters between cases and controls. Assessment of PT and its association with MRI parameters was done using Logistic regression.

Results: Wiberg angle (Subchondral) was higher in cases than controls (139.8± 6.5 vs. 134.5 ± 7.1; p = 0.003). Insall–Salvati ratio concerning patellar height was different between cases and controls (1.29 ± 0.23 vs. 1.13 ± 0.20; p = 0.002), so does Caton–Deschamps index (1.3 ± 0.20 vs. 1.1 ± 0.30; p = 0.004). Significant association with tendinitis were found [odds ratios (CI 95%)] for patellar structure [1.1 (1.0, 1.2)] and patellar height [1.3 (1.0, 1.7)] using logistic regression.

Conclusions: Patellar tendinitis is found to be significantly associated with increased subchondral patellar wiberg angle and patellar height.

Keywords: Patellar tendinits; Patellofemoral Joint; MRI; Patella; Sinding Larsoen Johansson disease.

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Dr Satyapraveen Samantula

Post Graduate, Dept of Radiology, Maharajah’s Institute of Medical Sciences