Abstract
We propose a grading system for contrast free MRI images of tennis elbow and evaluate the inter and intra observer variability of their interpretation.
Methods: Three senior orthopaedic surgeons were asked to blindly grade 0.2T dedicated extremity contrast free MRI images of elbows of patients who presented with varying degrees of symptomatic tennis elbow.
Our proposed grading system of 1 to 5 based on the pattern around the common extensor tendon was used.
Images of the symptomatic and contralateral non symptomatic elbows were graded blindly twice with an interval of 1 month by each surgeon.
Each surgeon graded 176 MRI images twice.
The grades were subsequently grouped into (I) grades 1 to 2 and (II) grades 3 to 5
Results: With regards to the intra observer agreement, consultant A showed 90.1% agreement, consultant B showed 90.6% agreement and consultant C 96.0% agreement. The mean intra observer agreement rate was 92.2%.
The inter observer agreement between consultant A and B was 82.46%, between A and C 67.1% and between B and C 80.1%.
It was also noted that there were systematic differences to the inter observer variability. Consultant A graded the images 3 to 5 on both occasions 52.9% of the time, consultant B graded 3 to 5 on both occasions 37.8% of the time and consultant C graded 3 to 5 on both occasions 23.3% of the time.
Conclusion: The intra observer agreement rate is high. There is however a greater inter observer variation but this variation is consistent. We suggest that the inter observer differences can be improved by (1) reducing the grades to positive or negative and (2) by group reeducation of the observers.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
