title: Partial double-layered patella in a nondysplasic adolescent.
abstract: Double-layered patella (DLP) is a rare patella-formation abnormality reported in association with multiple epiphyseal dysplasia. DLP is one of the five types of bipartite patella, caused by a coronal septum that divides the patella into anterior and posterior segments. Although the double layer of bone has been reported as complete, it may also manifest as partial, as in our case. A 13-year-old male patient attended A&E after accidentally falling and sustaining a direct injury to his left knee, with pain in the anterior surface of the right patella. He was diagnosed with an incomplete vertical fracture of the left patella. An axial view radiography indicated an external partial DLP. No bone dysplasia was found. Computed tomographic scan and MRI showed partial DLP and bone marrow oedema because of the injury in the femoral condyle, but no fracture. The reason for highlighting this type of patella abnormality is to present the case of a patient without bone dysplasia, either partial or incomplete, that has not been reported previously. We also wish to emphasize the importance of not confusing it with a fracture in standard radiographies.
authors.affiliation: Pediatric Trauma and Orthopaedic Section, Department of Surgery and Traumatology, Complejo Hospitalario de Navarra, Pamplona, Spain.
authors.forename: Serafín
authors.initials: S
authors.lastname: García-Mata
authors.forename: Angel
authors.initials: A
authors.lastname: Hidalgo-Ovejero
mesh_terms: D000293:Adolescent; D001848:Bone Diseases, Developmental / Q000150:complications; D005269:Femur; D050723:Fractures, Bone / Q000150:complications* / Q000000981:diagnostic imaging; D006801:Humans; D007719:Knee Joint / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D010009:Osteochondrodysplasias / Q000150:complications; D010146:Pain / Q000150:complications; D010329:Patella / Q000000981:diagnostic imaging / Q000293:injuries* / Q000473:pathology; D016059:Range of Motion, Articular; D014057:Tomography, X-Ray Computed