Acute Knee Fracture Diagnosed by Musculoskeletal Ultrasound
An 85-year-old male patient without routine medical care or known medical problems presented with acute onset knee pain. He had a mechanical fall, slipping on wet pavement and falling onto his right knee. Subsequently, he had difficulty ambulating with pain upon weight bearing and knee swelling. On arrival to the hospital, his vital signs were stable and basic laboratory studies were unremarkable, with a normal hemoglobin. A non-weight bearing X-ray of the knee showed generalized osteopenia, limiting the radiographic sensitivity for detecting a fracture. Bedside musculoskeletal ultrasound revealed a break in the articular cartilage (Fig.A, top arrow) and cortical bone of the lateral femoral condyle (Fig.A, bottom arrow), seen in maximum flexion of the transverse suprapatellar view of the femur and confirmed in the longitudinal view (not shown). Afterwards, a magnetic resonance imaging (MRI) confirmed the ultrasound finding of a non-displaced fracture of the lateral femoral condyle, on both coronal (Fig.B) and transverse (Fig.C) views, and additionally, a fracture of the lateral tibia (not shown). The patient was treated conservatively with a brace. It has been reported that up to 15% of intra-articular fractures will not be detected radiographically.1 Subsequently, CT or MRI imaging is usually performed to confirm the suspicion of a fracture. Musculoskeletal ultrasound may be a better cost-effective method for confirming occult intra-articular fractures, not seen on conventional radiography.