Daniel Fascia, Presenter: Nothing to Disclose

Dimitri Amiras, Abstract Co-Author: Nothing to Disclose

Andrew Hohnen MD, Abstract Co-Author: Nothing to Disclose

Nicholas Dominic Karl Wambeek MBBS, Abstract Co-Author: Nothing to Disclose

Patellar maltracking is a significant problem affecting a young and active population which often results in premature osteoarthritis. It is said to be related to a combination of anatomical and biomechanical factors. So far radiological assessments with CT and MR have focussed on static anatomical assessment. Utilising fast multi-slice cinematic CT, we have designed a method to assess the patellofemoral joint during realtime dynamic patient initiated active motion, allowing both conventional anatomical assessment and biomechanical analysis during the same study.

Symptomatic patients were selected by Orthopaedic surgeons using the Lysholm knee score. Using a 256-slice Phillips Brilliance CT, patients were scanned whilst actively extending their knee joints from 90 to zero degrees. Axial volume rendered images of the patellofemoral joint were generated from the animated sequence to recreate the patellar skyline view. Standard anatomical patellofemoral measurements as well as dynamic measurements to assess extent of patellar lateralisation and tilt were taken.

Our new dynamic CT method was effective in demonstrating patellar maltracking in patients with abnormal patellofemoral anatomy. It additionally had the advantage of demonstrating occult maltracking in a number of patients whose standard anatomical assessment was within normal ranges. Average radiation doses were acceptably low with a calculated body effective dose delivered <0.5mSv.

Dynamic CT of the patellofemoral joint during active patient motion is highly effective at quantifying the degree of patellar lateralisation and tilt during maltracking. It also has the unexpected advantage of revealing maltracking in a number of anatomically normal but symptomatic patients.

Our novel method of imaging the patellofemoral joint is a sensitive way of detecting maltracking in symptomatic patients and quantifying it. It has the advantage of being both more sensitive to maltracking and adding useful biomechanical information compared with current static anatomical cross sectional methods. The technique uses an acceptably low radiation dose for use in the target young-active population.

Fascia, D, Amiras, D, Hohnen, A, Wambeek, N, Realtime Dynamic CT of the Patellofemoral Joint: A New Approach to the Old Problem of Patellar Maltracking.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14016803.html