2023 ISAKOS Biennial Congress ePoster
The Tibial Tubercle - Trochlear Groove Distance. A Comparison Study Between EOS And MRI In The Paediatric Population
Ravi Teja Rudraraju, MD, Hyderabad, Telangana INDIA
Geoffrey T Murphy, BMed, MD, BSc (Med) Hons, Camperdown, New South Wales AUSTRALIA
Alexander S. Nicholls, MSc, FRACS, Sydney, NSW AUSTRALIA
Sydney Orthopaedic Research Institute, Sydney, NSW, AUSTRALIA
FDA Status Not Applicable
Summary
While EOS has several advantages for its use in children, being quick, inexpensive, and having reduced radiation, it should not be used for decision making regarding TT-TG distances while planning the management of patella femoral joint instability.
ePosters will be available shortly before Congress
Abstract
Background
In patella instability, the tibial tubercle-trochlear groove distance (TT-TG) is often used to
assists clinicians in determining whether soft tissue reconstruction alone will be sufficient or
if bony procedures are also needed. TT-TG distance is traditionally measured using CT or
MRI scan, which each have unique disadvantages in children. The EOS x-ray is an
increasingly available modality which could be used to assess TT-TG in this population. This
study aims to compare the relative reliability and accuracy of upright EOS low-dose
radiographic evaluation with that of MRI in a paediatric population.
Methods
Patients were included if they underwent both an MRI and EOS scans for the assessment of
knee pathology and were under the age of 16. Two authors recorded the TT-TG distances on
each modality at two separate time points. In the EOS images, the distance between the two
points was measured in the horizontal 2D plane. In the MRI images it was done in the plane
referenced by posterior femoral condylar axis. The intra- and inter-rater reliability was
assessed in each modality and between modalities.
Results
Twenty-four patients (27 knees) were included in the study. The mean TT-TG distance on
EOS scan was 13mm and for MRI 12mm. On inter- and intra-observer analysis both imaging
modalities had excellent reliability (0.97 ICC for EOS and 0.98 ICC for MRI inter-observer)
and repeatability (0.98-0.99 ICC for EOS and 0.99 ICC for MRI for intra-observer).
However, comparing the two imaging modalities (EOS vs MRI) within raters, the ICC was
fair (0.56 ICC for rater 1 and 0.63 ICC for rater 2).
Conclusion
While EOS has several advantages for its use in children, being quick, inexpensive, and
having reduced radiation, it should not be used for decision making regarding TT-TG
distances. MRI or CT are still required imaging tools in this setting. However, EOS can still
play a useful role in planning the management of patella femoral joint instability.
Level of evidence: Level II