(Kiosk 2) Bipartite Patella with Associated Chondral Defect of the Knee in a 14-year-old Female Athlete: A Case Report

Case Diagnosis: Bipartite patella with associated chondral defect of the lateral femoral trochlea

Case Description or Program Description: A 14-year-old multi-sport female athlete presented to sports medicine clinic with a 3-month history of gradual onset right lateral knee pain and intermittent knee swelling. Pain was exacerbated by running, climbing stairs, and squatting. She trialed 3 months of conservative measures, including relative rest and physical therapy, without improvement. On physical examination, she had subtle tenderness to palpation of the lateral and posterolateral corner of the knee. Active and passive range of motion of the bilateral knees and hips were full and symmetric. She experienced mild knee discomfort with deep squatting. Ligamentous testing and meniscal provocation maneuvers were negative. MRI of the knee revealed bipartite patella with reactive marrow edema in the secondary ossification center as well as a focal full-thickness chondral defect overlying the adjacent periphery of the lateral femoral trochlea. A small effusion was visualized but no loose chondral fragments were seen.

Setting: Outpatient pediatric sports medicine clinic

Assessment/Results: Given the patient had failed physical therapy, she was referred to orthopedic surgery. She underwent a successful lateral facetectomy of the patella as well as a lateral trochlea chondroplasty with cartilage biopsy for possible matrix-induced autologous chondrocyte implantation (MACI) in the future. She tolerated the procedure well.

Discussion (relevance): Bipartite patella is an anatomic variant that is typically asymptomatic but may produce knee pain in some cases. Chronic overuse along with anatomic predisposition of the bipartite patella can lead to patellofemoral friction syndrome, resulting in persistent pain. Associated injuries, such as chondral defects, can also occur which may necessitate surgical intervention.

Conclusions: In patients with persistent knee pain and findings of bipartite patella on radiograph, consider the possibility of symptomatic bipartite patella. Advanced imaging can help delineate a source of pain and assess for associated injuries such as patellofemoral pain and chondral changes.