Radiological assessment of the patellofemoral joint (PFJ) with regards to instability will be reviewed
Review functional anatomy and biomechanics
Review morphological risk factors for PFJ instability
Review the different surgical procedures that are currently performed
Demonstrate normal and abnormal post-surgical findings on imaging
The patellofemoral joint (PJF) is a complex joint
Formed by articulation of the patella and the femoral trochlea
Stability provided by:
The bony morphology of the joint
The quadriceps/ patella tendon
Atraumatic disorders of the PFJ commonly present as instability or anterior knee pain
Abnormal PFJ anatomy predisposes to acute lateral patellar dislocation-relocation
Clinical assessment with examination plays a vital role in the initial work up
Subsequent advanced imaging often required
The diagnosis and subsequent management of PFJ disorders can be challenging.
Imaging findings OR Procedure Details
Functional Anatomy and Biomechanics
Normal trochlea is concave with strict correlation between the bony contour and overlying cartilage
The retro-patellar articular surface - larger lateral facet,
the median ridge and medial facet. Fig. 2
There is the non-articulating “odd” facet,
which is located medial to the medial facet
4 types of trochlear morphology which can predispose to patellar instability described by Dejour 1 Fig. 3
Patellar dysplasia can occur.
Wiberg described 3 patellar shapes: V shape,
L shape (vertical,
small medial facet),
and a flat...
Radiologists working in both general and specialist centres will encounter cases of patellar instability.
Abnormality to either the dynamic or static stabilisers can lead to patella instability.
Assessment of radiographs and advanced imaging representa vital part of pre-operative assessment.
Knowledge of morphological abnormalities in cases of patella/ trochlear dysplasia,especially on plain radiography,
may expedite specialist referral and further imaging.
Numerous surgical procedures are performed
Awareness of the commonly performed procedures and their post operative appearances will enable the radiologist to assess for possible complications.
Adeleine P (1990) [Dysplasia of the femoral trochlea].
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Wiberg G (1941) Roentgenographs and Anatomic Studies on the Femoropatellar Joint: With Special Reference to Chondromalacia Patellae.
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Bose K (1995) A cadaver study of the function of the oblique part of vastus medialis.
J Bone Jt Surg Br 77:225–231
Amis a a (2005) The effects of articular,
or muscular deficiencies on...
Dr Neeraj Purohit MBChB,
Musculoskeletal Radiology Fellow
Royal National Orthopaedic Hospital,