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Surgical management of patellofemoral instability. I. Imaging considerations

  • Neeraj PurohitEmail author
  • Nicholas Hancock
  • Asif Saifuddin
Review Article

Abstract

The patellofemoral joint is a complex joint that relies on both bone and soft tissues for its stability. Dysfunction of the patellofemoral joint, whether pain or instability, is a common cause of medial consultation. Thorough clinical and imaging assessment is important for managing these patients, who may require a combination of a bony and soft tissue surgical procedure. Trochlear dysplasia, a cause of anterior knee pain and patellar instability, has been classified using conventional radiography. Radiographic signs on a lateral projection, such as the “double contour” sign and the “crossing sign”, can alert the radiologist to the grade of trochlear dysplasia. Magnetic resonance imaging (MRI) is the gold standard for accurately assessing the soft tissue around the patellofemoral joint, such as the medial patellofemoral ligament and the medial and lateral patella retinacula, especially in the context of a transient patella dislocation. Risk factors for patellofemoral instability, such as patella alta, an increased tibial tubercle to trochlear groove distance and trochlear dysplasia, can all be assessed on MRI. Advanced imaging techniques such as dynamic MRI and CT are able to demonstrate patellar maltracking. These techniques can also be employed to reliably assess the outcomes of treatment. In this article, we review the normal and abnormal pre-operative imaging findings of the knee extensor mechanism in relation to patellofemoral joint instability. This review provides a useful tool for the reporting radiologist and highlights the imaging findings that are of relevance to the orthopaedic surgeon.

Keywords

Knee Extensor mechanism Patellofemoral Instability Pre-operative assessment Post-operative assessment 

Notes

Compliance with ethical standards

Conflicts of interest

The authors declare that they have no conflicts of interest.

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Copyright information

© ISS 2018

Authors and Affiliations

  • Neeraj Purohit
    • 1
    Email author
  • Nicholas Hancock
    • 2
  • Asif Saifuddin
    • 3
  1. 1.Department of RadiologyUniversity Hospital Southampton NHS Foundation TrustSouthamptonUK
  2. 2.Department of Trauma and OrthopaedicsUniversity Hospital Southampton NHS Foundation TrustSouthamptonUK
  3. 3.Department of RadiologyThe Royal National Orthopaedic Hospital NHS TrustStanmoreUK

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