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.
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.
Controlled laboratory study.
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°, 30°, and 60° of abduction with 0° of rotation. For both dual-row repairs, 5 rotation positions were tested.
The greatest contact areas at neutral rotation were achieved at 0° 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° 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).
For a given repair, increasing abduction at neutral rotation reduced footprint contact. Internal rotation to 60° provided among the highest contact measurements. The modified double-row technique provided the most contact.
Results are consistent with the practice of immobilizing the shoulder with 30° or less of abduction and up to 60° of internal rotation to optimize footprint contact. A dual-row repair may maximize contact when initiating rehabilitation that involves abduction and rotation.