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A 30-year-old woman with acute knee injury
  1. Suzanne Witjes1,
  2. Tammo H Pels Rijcken2,
  3. Cor P van der Hart3
  1. 1Department of Orthopaedic Surgery, Academic Medical Centre, Amsterdam, The Netherlands
  2. 2Department of Radiology, Tergooi Hospitals, Hilversum, The Netherlands
  3. 3Department of Orthopaedic Surgery, Bergman Clinics, Naarden, The Netherlands
  1. Correspondence to Suzanne Witjes, Department of Orthopaedic Surgery, Academic Medical Centre, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; suzanne.witjes{at}gmail.com

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Additional MRI showed a prominent bone contusion at the location of the radiographically visible depression in the lateral femur condyle (figure 2). Remarkably, also a bone bruise was observed at the posterolateral side of the tibial plateau (figure 3). Furthermore, an empty notch sign, full disruption of the anterior cruciate ligament (ACL), oedema around an intact medial collateral ligament and an accompanying tear of the posterior horn of the lateral meniscus were also observed on MR (figure 4). The increased depth of the femoral notch, visible on the lateral plain knee radiograph, is an infrequent but characteristic radiological image, known as ‘lateral (femoral) notch sign’.

Figure 2

Sagittal MR fat suppressed PD-weighted image shows marrow oedema (solid arrow) around a deep femoral sulcus in the lateral femoral condyle. PD, proton density.

Figure 3

Coronal short T1 inversion recovery (STIR) heavily T2-weighted MRI shows bone bruise (solid arrow) on the posterolateral side of the tibial plateau as well.

Figure 4

Sagittal non-fat-suppressed PD-weighted images show an anterior cruciate ligament tear (A, solid white arrow) and a tear of the posterior horn of the lateral meniscus, reaching the surface (B, white arrow). PD, proton density.

The ‘lateral notch sign’ is an abnormally deep lateral condylopatellar sulcus due to a compression fracture of the lateral femoral condyle, which has been described as an indirect sign of ACL rupture. It is caused by impression of the lateral femoral condyle against the posterior lateral corner of the tibial plateau, during subluxation in the case of acute ACL tear, similar to a Hill-Sachs lesion of the humerus caused by anterior dislocation of the glenohumeral joint. This impaction causes a pattern of injuries well known as ‘kissing contusions’, which are usually radiographic occult injuries to the cartilage and bone. In 92–100% of patients with acute ACL rupture, proved with surgery, bone contusions can …

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