What is rotator cuff repair?
The rotator cuff is four tendons that wrap the top of your arm bone and hold it centred in the socket. They are what let you lift, reach and rotate. When one tears off the bone, the shoulder loses both its power and its anchor.
A rotator cuff repair puts it back. Working arthroscopically through incisions the width of a pen, your surgeon cleans the frayed tendon edge, prepares the bone so it can heal, and reattaches the tendon using small anchors set into the bone with sutures running from them. Larger or more retracted tears sometimes call for an open or mini-open approach, and how many anchors are used, in one row or two, is a judgement your surgeon makes when they can see the tear in front of them.
What the operation cannot do is turn back time. The stitches hold the tendon in place, but it is your own biology that heals it back onto the bone, and that biology is not equally willing at every stage of the tear.
The window, and why it closes. A full-thickness rotator cuff tear does not heal on its own, and tears tend to get bigger. In prospective ultrasound studies of degenerative tears, about half of the full-thickness ones had enlarged within five years. Size is what matters, because it predicts whether a repair will actually heal: research published in Acta Orthopaedica found healing rates at one year fell as tears got larger, from roughly two thirds of small and medium tears down to about a quarter of massive ones. Left long enough, the muscle retracts and fills with fat, and at that point the tendon can no longer be pulled back and stitched down. The operation on offer is then often no longer a repair, but a reverse shoulder replacement.