To demonstrate that the shoulder AP view radiograph does not accurately reflect true glenohumeral (GH) joint space narrowing when compared to the Grashey view.
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.
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.
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.