Background: An abduction pillow and abduction and rotation exercises are commonly used after rotator cuff repair. The effect of glenohumeral abduction and rotation on footprint contact has not been elucidated.
Hypothesis: Abduction will decrease tendon-to-bone contact for all repairs. A modified double-row repair will maintain footprint contact more effectively at each position of humeral abduction and rotation than double- or single-row repairs.
Study design: Controlled laboratory study.
Methods: In 6 fresh-frozen human shoulders, a modified double-row supraspinatus tendon repair was performed; a suture limb from each of 2 medial anchors was bridged over the tendon and fixed laterally. Double- and single-row repairs were performed sequentially; a total of 3 repairs were tested. For all repairs, a Tekscan pressure sensor was fixed at the tendon-footprint interface. The tendon was loaded with 30 N. The shoulders were tested at 0 degrees , 30 degrees , and 60 degrees of abduction with 0 degrees of rotation. For both dual-row repairs, 5 rotation positions were tested.
Results: The greatest contact areas at neutral rotation were achieved at 0 degrees of abduction for the modified double-row, double-row, and single-row repairs (151.3 +/- 10.7 mm2, 80.7 +/- 30.0 mm2, and 61.3 +/- 26.1 mm2, respectively), with values decreasing as abduction increased. Each repair was significantly different from one another at each abduction angle (P < .05), except between single- and double-row repairs at 0 degrees of abduction. Mean interface pressure exerted over the footprint was greater for the modified double-row technique than for the other techniques at each abduction angle (P < .05). With respect to rotation, the modified double-row repair had significantly more footprint contact than did the double-row repair at each position tested (P < .05).
Conclusion: For a given repair, increasing abduction at neutral rotation reduced footprint contact. Internal rotation to 60 degrees provided among the highest contact measurements. The modified double-row technique provided the most contact.
Clinical relevance: Results are consistent with the practice of immobilizing the shoulder with 30 degrees or less of abduction and up to 60 degrees of internal rotation to optimize footprint contact. A dual-row repair may maximize contact when initiating rehabilitation that involves abduction and rotation.