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The Perfect-Circle Technique Demonstrates Poor Inter-Rater Reliability in Measuring Posterior Glenoid Bone Loss on
Nata Parnes1,2, Kyle J Klahs3, Alexis B Sandler3
1Department of Orthopaedic Surgery and Rehabilitation, Carthage Area Hospital, Carthage, New York, U.S.A.
Purpose:
To evaluate the reliability of the "perfect-circle" methodology for measurement of glenoid bone loss with magnetic resonance imaging (MRI) in patients with posterior glenohumeral instability.
Methods:
A prospective chart review was performed on patients who underwent isolated arthroscopic posterior labral repairs in our institution's electronic medical records between January 1, 2021, and June 30, 2021. Inclusion criteria included isolated posterior shoulder instability with posterior labral repair and corroborated tears on MRI. A total of 9 raters, either sports or shoulder and elbow fellowship-trained orthopaedic surgeons, each evaluated the affected shoulder MRI scans twice, at over 2 weeks apart. Measurements followed the "perfect-circle" technique and included projected anterior-to-posterior (AP) glenoid diameter, amount of posterior bone loss, and percentage of posterior bone loss.
Results:
Ten consecutive patients between the ages of 17 and 46 years with diagnosed posterior glenohumeral instability were selected. The average age was 28 ± 10 years, and 60% of patients were male. The patient's dominant arm was affected in 40%, and 50% of cases involved the right shoulder. The average glenoid diameter was 29.62 ± 3.69 mm, and the average measured bone loss was 2.8 ± 1.74 mm. The average percent posterior glenoid bone loss was 9.41 ± 5.78%. The inter-rater reliability was poor for the AP diameter and for the posterior glenoid bone loss with intraclass correlation coefficients at 0.30 (0.12-0.62) and 0.22 (0.07-0.54) respectively. The intrarater reliability was poor for AP diameter and moderate for posterior glenoid bone loss, with intraclass correlation coefficients at 0.41 (0.22-0.57) and 0.50 (0.33-0.64), respectively.
Conclusions:
Using the "perfect-circle" technique for evaluating posterior glenohumeral bone loss has poor-to-moderate inter- and intrarater reliability from MRI.
Level Of Evidence:
Level IV, prospective diagnostic study.
Insights
The "perfect-circle" MRI method for assessing posterior glenoid bone loss in shoulder instability shows poor reliability. This technique is unreliable for surgeons measuring bone loss from posterior shoulder instability.
Area of Science:
- Orthopaedic Surgery
- Radiology
- Sports Medicine
Background:
- Posterior glenohumeral instability is a significant cause of shoulder pain and dysfunction.
- Accurate assessment of glenoid bone loss is crucial for effective treatment planning.
- Magnetic resonance imaging (MRI) is a common modality for evaluating shoulder pathology.
Purpose of the Study:
- To evaluate the reliability of the "perfect-circle" methodology for measuring glenoid bone loss using MRI in patients with posterior glenohumeral instability.
- To determine the inter- and intrarater reliability of the "perfect-circle" technique for assessing posterior bone loss.
Main Methods:
- Prospective chart review of patients undergoing arthroscopic posterior labral repair.
- Inclusion of patients with isolated posterior shoulder instability and MRI-corroborated tears.
- Evaluation of MRI scans by 9 fellowship-trained orthopaedic surgeons, with each rater assessing scans twice over 2 weeks apart.
- Measurements included projected anterior-to-posterior (AP) glenoid diameter, amount of posterior bone loss, and percentage of posterior bone loss using the "perfect-circle" technique.
Main Results:
- Ten patients (17-46 years old, 60% male) with posterior glenohumeral instability were analyzed.
- Average posterior glenoid bone loss was 9.41% ± 5.78%.
- Inter-rater reliability was poor for AP diameter (ICC=0.30) and posterior bone loss (ICC=0.22).
- Intrarater reliability was poor for AP diameter (ICC=0.41) and moderate for posterior bone loss (ICC=0.50).
Conclusions:
- The "perfect-circle" technique demonstrates poor-to-moderate inter- and intrarater reliability for evaluating posterior glenoid bone loss on MRI.
- This suggests limitations in the "perfect-circle" method's consistency for assessing posterior bone loss in shoulder instability.
