Background: An inflamed and thickened medial patellar plica (MPP) caused by repeated mechanical irritation from trauma or overuse leads to impingement between the anterior medial femoral condyle and the medial articular facet of the patella and produces pain or clicking, which is known as MPP syndrome. In patients with MPP syndrome, cartilage damage may occur depending on the shape of the MPP and the duration of the impingement.
Case presentation: Preoperative magnetic resonance imaging in a 17-year-old male patient with MPP syndrome showed a hypertrophic MPP along with an abnormal notch in the articular surface of the medial femoral condyle. We considered that the impinged hypertrophic plica between the anterior medial femoral condyle and the medial articular facet of the patella resulted in cartilage damage on the articular surface of the medial femoral condyle. However, during arthroscopic surgery, we found that the cartilage of the notch, which was located beneath the MPP, was completely intact. We concluded that this abnormal notch had developed gradually in the MPP without cartilage damage.
Conclusions: Surgeons should be mindful that acquired plica-induced notches in the articular surface of the medial femoral condyle can present in patients with MPP syndrome.
Keywords: Articular surface; Cartilage damage; Knee; Medial femoral condyle; Medial patellar plica.