An acquired plica-induced notch in the medial femoral condyle in a patient with medial patellar plica syndrome: a case report

Abstract

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.

Fig. 1

Preoperative axial (a) and sagittal (b) proton density-weighted images showing medial patellar plica (white arrows). c Idiopathic groove is observed in the articular surface of the medial femoral condyle (white asterisk). d Postoperative axial proton density-weighted image after excision of the medial patellar plica

Fig. 2

Intraoperative arthroscopic views. a Medial patellar plica (MPP) with a tight and hypertrophic margin is observed, along with an abnormal notch in articular surface of the medial femoral condyle beneath the MPP (black asterisk). b The MPP runs downwards and merges with the synovial membrane covering the infrapatellar fat pad. c The MPP becomes impinged in the patellofemoral joint above an abnormal notch of the medial femoral condyle (black asterisk). d The MPP is excised with scissor forceps

Fig. 3

Histological findings of the resected medial patellar plica stained with hematoxylin and eosin. Scale bars = 2 mm. Fibrosis (dense fibers) are observed, and edema-like stroma can be seen in some parts. Infiltration of inflammatory cells was observed in fibrous tissues covered with synovial membrane cells