Displaced Longitudinal Stress Fracture of the Patella

Abstract

Stress fractures often occur in physically active individuals as a result of repetitive strenuous muscle and tendon forces acting on bones that have not adapted to such forces1-3. To our knowledge, the literature contains no reports of displaced longitudinal stress fractures of the patella requiring open reduction and internal fixation. The quadriceps muscle and patellar tendon produce extensive forces that can result in a displaced transverse patellar stress fracture2-7. The less strong vertical patellar restraints, including the medial patellofemoral ligament8, produce most of the ligamentous patellar stability in the lateral direction near knee extension8. In cases of acute traumatic patellar dislocation, the osseous structure of the patella is compromised mostly in the lateral direction—e.g., by avulsion of the medial patellofemoral ligament insertion—causing a medial margin fracture of the patella9. We are not aware of any previous reports of repetitive stress causing a displaced longitudinal patellar stress fracture. Here, we describe a case of a displaced longitudinal stress fracture of the patella in a female athlete. The patient was informed that data concerning the case would be submitted for publication, and she consented. An eighteen-year-old female athlete who played floorball (a popular European team sport that is a variant of floor hockey) presented with chronic anterior knee pain that had begun a few months previously without any specific injury event. She was an international-level athlete, and her training had become more difficult because of the persistent anterior knee pain; however, she continued to exercise at a reduced intensity. At the first visit to an orthopaedic surgeon, radiographs were considered to show normal findings and clinical examination revealed no specific findings other than anterior knee pain with some tenderness of the patella. She was diagnosed with nonspecific anterior …