The Grashey True Shoulder AP X-Ray Accurately Reflects Glenohumeral Joints Space and Predicts PRP Efficacy, The Traditional AP Does Neither
Purpose: To demonstrate that the shoulder AP view radiograph does not accurately reflect true glenohumeral (GH) joint space narrowing when compared to the Grashey view.
Methods and Materials: A total of 111 patients (122 shoulders) who received evaluation for various shoulder pathologies were included in the study. All patients received baseline Grashey and AP view radiographs. A comparative analysis based on joint space was performed to compare both radiographs of the shoulder. A subgroup of 45 shoulders receiving PRP injection for the treatment of glenohumeral osteoarthritis (GHOA) had previously shown significant efficacy on survivorship, global improvement, SANE and DASH evaluation.
Results: The mean Grashey joint space was 2.8 mm compared to 5.3 mm for the AP joint space. The mean joint space difference between the two views was 2.5 mm (P < 0.0001). Evaluation of the joint space, as measured by AP radiographs, resulted in a 57.4% false negative rate for glenohumeral osteoarthritis. A total of 8 patients received a joint replacement at two year follow up. Of these patients, 7 were in the 0-1 mm Grashey joint space group while only 4 were in the 0-1 mm AP joint space group. There was a 25.3% (p=0.04) difference in the number of responders (≥ 30% Global Improvement) between the 0-1 and 2+ Grashey groups at 6 months follow up. The difference in the number of responders when comparing the AP groups was not statistically significant.
Conclusion: The AP radiograph of the shoulder does not accurately measure, and tends to overestimate, the GH joint space, resulting in a significant amount of false negative GHOA diagnoses. The Grashey view radiograph correlated with clinical outcomes further validating the importance of obtaining an accurate GH joint space, i.e. Grashey radiograph.