To recognise MRI features of patellar ligament-lateral femoral condyle friction syndrome (PL-LFC FS) To recognise MRI features that allow differentiation of PL-LFC FS from similiar anterolateral knee soft tissue pathologies

Introduction Anterior knee pain is a common presentation Several causes associated with the juxta-patellar soft tissues Occasionally find high signal in anterolateral knee on fluid sensitive sequences: - Can be the primary pathology - Can be incidental - Can be symptomatic or asymptomatic Less common anterolateral knee ‘non-articular’ pathologies include (Fig. 1): Patellar ligament - lateral femoral condyle friction syndrome Iliotibial band friction syndrome Excess lateral pressure syndrome Hoffa's disease Lateral plica syndrome All these entities demonstrate high signal in fluid sensitive sequences in the...

Imaging Findings – PL – LFC FS Fig. 2 High signal in superolateral Hoffa’s fat pad Reduced AP distance between PL and lateral trochlear Normal LFC trochlear ridge Normal patellar tendon Fig. 3 High signal in superolateral Hoffa’s fat pad Rest of Hoffa’s fat pad is normal Marginal patella alta Fig. 4 High signal in superolateral Hoffa’s fat pad Reduced AP distance between PL and lateral trochlear Small joint effusion Fig. 5 High signal in superolateral Hoffa’s fat pad Patella alta Imaging Findings – ITB...

PL-LFC FS is a not uncommon cause of anterolateral knee pain There are multiple causes of high signal on fluid sensitive sequences in the anterolateral knee MR imaging features allow accurate differentiation between PL-LFC FS and its mimics Acknowledgements: Dr Gary Shepherd -Musculoskeletal Radiologist, Qscan Radiology Clinics, Brisbane Dr Russell Bourne -Orthopedic Surgeon, Nambour General Hospital, Nambour

Dr Craig Hacking BSc MBBS MRI Radiology Fellow Nambour General Hospital Nambour, Qld, Australia Contact: [email protected] Dr James Challen MBBS FRANZCR Consultant Radiologist Nambour General Hospital Nambour, Qld, Australia

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