Summary

Medial and bilateral pulley lesions are associated with a dysplastic shallow intertubercular groove

Abstract

Purpose

To investigate the influence of the bony morphology of the intertubercular groove (IG) on the development of different types of biceps reflection pulley (BRP) injuries.

Methods

221 Patients with a preoperative diagnosis suspecting BRP injury, who underwent arthroscopy, were retrospectively analysed. Surgeons described the presence or absence as well as type of pulley injury (medial, lateral or bilateral) in the operative report. The intertubercular groove was evaluated on MRIs after a standardised triplanar reconstruction: The axial plane was reconstructed in 3 planes at the level of and in line with the highest points of both the greater and lesser tuberosity and aligned perpendicular to the floor of the IG. The IG depth, width, medial wall angle (MWA), lateral wall angle (LWA) and total opening angle (TOA) were measured. IG depth and width were expressed relative to the diameter of the average humeral head. All measurements were performed by two clinicians independently and averaged.

Results

Of 166 included cases 43 had bilateral, 65 medial and 38 lateral BRP lesions as confirmed during arthroscopy. 20 patients had intact BRPs and represented the control group. The interrater correlation coefficient showed a high degree of reliability (0.843 – 0.955).
Shoulders with a medial or bilateral BRP injury had a flatter MWA (38,8° or 40,0° vs. 47,9°, p < 0,001), wider TOA (96,1° or 96,6° vs. 82,6°, p < 0,001), greater width (12,5 or 12,3 vs. 10,8 mm, p < 0,01) and shallower depth (5,5 or 5,4 vs. 6,2 mm, p < 0,001) compared to the control group. There was no significant difference in the IG morphology of patients with medial vs bilateral BRP lesions. The IG morphology of those with lateral BRP injuries was not significantly different from those with intact BRPs in any measurements. The odds ratio for a medial or bilateral BRP injury when the TOA exceeded 95° was 6.8 (CI 3.04 – 15.2).

Conclusion

A dysplastic type of IG morphology with a wide TOA, flat MWA, decreased depth and increased width is associated with the presence of medial and bilateral BRP injuries. A TOA of > 95° increases the odds for a medial or bilateral BRP injury 6.8-fold, which makes this a useful diagnostic marker. In contrast, lateral BRP injuries are not associated with dysplastic IG morphology. This knowledge can help inform a decision to perform concomitant biceps tendon surgery during rotator cuff repair.