A shoulder replacement (shoulder arthroplasty) is a procedure where the damaged surfaces of the joint are replaced with artificial components, typically made of metal and plastic, to relieve chronic pain and restore movement. Physical therapy (PT) is a necessary step following the operation to guide recovery and ensure the new joint functions correctly. The timing of when to begin PT is often the most important factor in the success of the entire recovery process. A structured rehabilitation program protects the surgical repair while gradually reintroducing mobility and strength.
The Critical Initial Phase Protecting the Surgical Repair
The immediate period following shoulder replacement surgery, generally spanning the first two to six weeks, is dedicated entirely to protecting the soft tissues repaired during the operation. This phase requires continuously wearing a sling or immobilizer to prevent the patient from actively moving the new joint. The primary goal is biological healing, which requires rest for the muscles and tendons to reattach and secure the new implant.
During this protective time, the patient is restricted from using the operated arm to lift, push, pull, or perform any movement using the shoulder’s own muscle power. To prevent the joint from stiffening, gentle, controlled movement is introduced as passive range of motion (PROM). PROM is movement supplied by an external source, such as a physical therapist or a specialized machine, with the patient’s muscles completely relaxed.
The patient’s muscles are not engaged during PROM exercises, ensuring the healing surgical site is not stressed or pulled. This early, controlled motion helps maintain joint surface health, reduce swelling, and prevent scar tissue formation without jeopardizing the repair. This initial stage of rehabilitation is distinct from the formal, supervised physical therapy program that begins later.
Standard Timeline for Initiating Formal Physical Therapy
The transition to formal, outpatient physical therapy typically begins between two and six weeks following surgery, depending on the patient’s healing rate and the surgeon’s protocol. This phase shifts the focus from purely passive movement to introducing the patient’s own muscle power. The key milestone at this time is the introduction of active-assisted range of motion (AAROM).
AAROM is a transitional phase where the patient engages the shoulder muscles to start a movement but requires assistance to complete the full range of motion. This assistance can come from the unoperated arm, a pulley system, or a device like a cane or dowel, helping to push the operated arm into a raised position.
This incremental introduction of muscle activation is carefully managed to avoid excessive strain on healing tendons and muscles. Unlike PROM, AAROM begins to build neuromuscular control and encourages the muscles to work, while external help ensures the motion stays within a safe range. The primary goal during this timeline is to restore mobility and flexibility before attempting to build strength.
Factors That Adjust the PT Start Date
The timeline for initiating active motion in physical therapy depends highly on the specific type of shoulder replacement performed. The two most common types, Standard Total Shoulder Arthroplasty (TSA) and Reverse Total Shoulder Arthroplasty (RTSA), have significantly different protocols based on their reliance on surrounding muscles. A Standard TSA replaces the joint surfaces, retaining the natural ball-and-socket configuration, and relies on a healthy rotator cuff for power and stabilization.
For a Standard TSA, the surgeon often repairs or reattaches the subscapularis tendon, one of the rotator cuff muscles, necessitating a slower progression to protect the repair. Formal PT with active motion is delayed, typically until the soft tissue has had adequate time to heal, usually around four to six weeks post-operation. Starting active movement too early risks tearing the repaired tendon, which could lead to surgical failure.
In contrast, a Reverse Total Shoulder Arthroplasty (RTSA) reverses the ball and socket, placing the ball on the shoulder blade and the socket on the arm bone. This design allows the larger, stronger deltoid muscle to take over the function of the rotator cuff, which is often severely damaged or non-functional in RTSA patients. Because the RTSA does not rely on a healed rotator cuff for stability, patients can often begin active range of motion exercises sooner than those with a standard TSA, sometimes as early as two to three weeks post-operation. Other patient-specific variables, such as bone density, overall health, and the quality of the surrounding soft tissues, also contribute to the surgeon’s decision to advance or delay the PT start date.
Milestones and Progression Through the PT Stages
Once formal physical therapy is underway, the patient progresses through distinct stages, with goals shifting from mobility to strength. The first major milestone is achieving a functional range of motion, which is the movement needed for basic activities like reaching for a cup or combing hair. This mobility-focused phase often lasts for the first eight to twelve weeks, concentrating on exercises to improve flexibility and joint movement.
The next major transition point is the introduction of strengthening exercises, which typically begins around the three-month (twelve-week) mark post-surgery. This delay ensures the soft tissues have matured sufficiently to handle resistance without damage. Strengthening work initially focuses on gentle isometric exercises, where the muscle is contracted without the joint moving, before advancing to light resistance using bands or small weights. The final goal of rehabilitation is building the endurance and power necessary to return to daily activities and, eventually, low-impact sports.