2023 ISAKOS Biennial Congress ePoster
Axial Patello-Trochlear Overlap on MRI: A Reliable Alternative for the Evaluation of Patellar Height
Tamer Sweed, FRCS(Orth), Birmingham, West-midlands UNITED KINGDOM
Tarek Boutefnouchet, MBChB MRCS PGCMed MSc FRCS (Tr&Orth) Dip. FIFA Med, Birmingham UNITED KINGDOM
Steve Amerasekera, MB BChir MRCP FRCR, Birmingham UNITED KINGDOM
Zerlene Lim, MBBS, BSci (Med), FRANZCR, Birmingham UNITED KINGDOM
Surabhi Choudhary, MBBS, MD, FRCR, Birmingham UNITED KINGDOM
Tanweer Ashraf, MS, MRCS, FRCS, MSc, FRCS(Tr&Orth), Birmingham, West Midlands UNITED KINGDOM
University Hospitals Birmingham NHS Foundation Trust, Birmingham, UNITED KINGDOM
FDA Status Not Applicable
Summary
We present axial patello-trochlear overlap; a new index for measurement of patellar height on axial MRI, which can prove valuable in overcoming issues with sagittal image measurements.
ePosters will be available shortly before Congress
Abstract
Introduction
There are several imaging-based measurements for patello-femoral height. Available methods rely predominantly on sagittal images. The latter can be misleading with sagittal oblique slices and when the patella is tilted and/or chronically subluxed. In this study we describe a simple method of patellar height measurement using axial MRI overlap.
Materials And Methods
A retrospective observational analysis of 97 knees from 251 patients was conducted. Cases were selected following the exclusion of scans with fractures, massive effusion, patello-femoral pathology. Axial patello-trochlear overlap (APTO) was measured on the axial MRI images as follows: (1) Patellar length (P): expressed as the number of axial images showing patellar articular surface (2) Trochlear overlap (T): the number of axial images showing overlap between patellar articular surface and articular surface of lateral trochlea. APTO is the ratio T/P. All measurements were carried out independently and on two separate occasions by 6 raters 2 orthopaedic consultants, one knee surgery fellow, 2 consultant musculoskeletal radiologists and one radiology fellow. As a control conventional patello-trochlear index were measured for all patients by a senior musculoskeletal radiologist.
Results
The mean APTO value was 36.7 (range 14.2 to 66.6; SD 11.4). There was a positive correlation with patello-trochlear index (Pearson correlation coefficient: 0.76, P < 0.001). Intra-observer reliability was good (ICC: 0.66 95 CI 0.54, 0.76, P < 0.001). Inter-observer reliability was fair (ICC: 0.51, 95 CI 0.41, 0.6, P < 0.001).
Conclusion
In the present proof of concept study APTO was shown to be a reliable measurement of patellar height and correlated with patella-trochlear indices. The method described can prove valuable in overcoming issues with sagittal image measurements.