Jumper's knee, osteochondral injury, and excessive lateral pressure syndrome, on the background of trochlear dysplasia

Case contributed by Bálint Botz

Presentation

Prior traumatic patellar dislocation, chronic knee pain since the injury.

Patient Data

Age: 20 years
Gender: Male

Slight patella alta, otherwise unremarkable. 

Edema of the inferior pole of the patella, thickening and high signal of the adjacent proximal patellar tendon. Findings in line with jumper's knee

Focal osteochondral defect of the superior lateral patellar facet. 

Abnormal lateral tilt of the patella suggesting excessive lateral pressure syndrome, and moderately (1.5) increased Insall-Salvati ratio

Decreased lateral trochlear inclination (3°) and smaller medial trochlear facet (ratio 0.3), combined with a moderately increased TT-TG distance (18 mm) and increased trochlear sulcal angle (147°) demonstrating trochlear dysplasia.

Subtle effusion of the proximal tibiofibular joint, could represent instability or prior injury. 

Annotated images sequentially show:

  1. increased sulcal angle
  2. abnormal lateral patellar tilt
  3. TG
  4. TT and TT-TG distance, which is borderline increased
  5. abnormal low lateral trochlear inclination
  6. Small medial facet
  7. Borderline increased Insall-Salvati ratio 

Case Discussion

The trochlear dysplasia and excessive lateral pressure syndrome predispose the patient to osteochondral damage, patellar dislocation, as well as patellar tendonitis. 

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