In fact surgery does not heal your body in the slightest. It causes more damage. The only reason that surgery is beneficial despite the damage that it causes is that it removes an obstacle to the bodies ability to heal its self. Take the rotator cuff tear for example. If the tear is so severe that the tendon has been pulled away from it's attachment point then there is no way that the body can by its self put that back where it belongs and then heal it.
https://www.quora.com/Is-it-possible-for-a-rotator-cuff-injury-to-heal-itself-without-surgery-If-the-pain-of-the-injury-goes-away-is-the-underlying-injury-healed
Then, the next three months are focused on strength and functional recovery. So by six months most patients are doing very well but we tell all patients who have rotator cuff surgery (especially those with large or massive tears) that they can continue to improve for up to 12 months after the operation.
https://www.sharecare.com/health/rotator-cuff/how-healing-rotator-cuff-surgery
Total recovery from rotator cuff surgery can take up to about six months, but it will take about 12 months for you to feel completely happy with your outcome. While pain relief during recovery is predictable, function and range are not always as predictable.
https://www.sharecare.com/health/rotator-cuff/how-healing-rotator-cuff-surgery
But if, as in your situation, the injury involves a large tear in the muscle, surgery can be a good option. In the past, rotator cuff surgery required a large 2- to 4-inch incision. But over the past 10 years, arthroscopic rotator cuff surgery has become more common and can often be used to repair even large tears. During arthroscopic surgery, the surgeon makes three or four small incisions in the shoulder.
http://newsnetwork.mayoclinic.org/discussion/arthroscopic-surgery-often-a-good-option-for-torn-rotator-cuff/
It takes rotator cuff repairs eight to 12 weeks to heal (the torn tendon has to reconnect to the bone). So the first three months are focused entirely on healing (first six weeks no motion often in larger tears; and then the next six weeks on slowly regaining motion).
https://www.sharecare.com/health/rotator-cuff/how-healing-rotator-cuff-surgery
Recovery time varies but, generally, full recovery from rotator cuff surgery takes from six months to one year. The shoulder moves with the help of two main muscle groups. The top layer is the deltoid muscle. Under that are the thin, strong muscles that surround the shoulder joint and make up the rotator cuff.
http://newsnetwork.mayoclinic.org/discussion/arthroscopic-surgery-often-a-good-option-for-torn-rotator-cuff/
To find out if you have a torn rotator cuff, your doctor will start with a history of the injury and a physical examination of the shoulder. During the exam, he’ll check your range of motion and muscle strength. He’ll also see what movements make your shoulder hurt.
http://www.webmd.com/fitness-exercise/guide/rotator-cuff-tear
If less than 50% of the tendon is torn, then the tear usually does not require repair. In these cases, removing the frayed and damaged tendon (debridement), as well as removing any inflammation, will often relieve symptoms. If more than 50% of the tendon has been torn, a rotator cuff repair will typicallybe performed.
https://www.verywell.com/what-is-a-partial-tear-of-the-rotator-cuff-2549766
Your rotator cuff is a group of four muscles and tendons that stabilize your shoulder joint and let you lift and rotate your arms. There are two kinds of rotator cuff tears. A partial tear is when the tendon that protects the top of your shoulder is frayed or damaged.
http://www.webmd.com/fitness-exercise/guide/rotator-cuff-tear
Updated July 27, 2016. The rotator cuff is a group of tendons and muscles that surround the shoulder joint. Rotator cuff tears are a common orthopedic problem, and often these tears are so-called partial tears of the rotator cuff. A partial tear of the rotator cuff is an area of damage to the rotator cuff tendons, where the tear does not go all the way through the tendons.
https://www.verywell.com/what-is-a-partial-tear-of-the-rotator-cuff-2549766
how long does it take a torn rotator cuff to heal?
It takes six month to one year for a torn rotator cuff to heal.