Reverse Shoulder Replacement: Understanding Movements to Avoid for Optimal Recovery

What movements should be avoided with reverse shoulder replacement?

Following a reverse shoulder replacement (reverse total shoulder arthroplasty, or rTSA), patients must strictly avoid specific movements, primarily those combining adduction, internal rotation, and extension, to prevent dislocation and ensure optimal recovery and implant longevity.

Understanding Reverse Shoulder Arthroplasty (RSA)

Reverse shoulder arthroplasty (RSA) is a highly effective surgical procedure for individuals suffering from severe shoulder arthritis with rotator cuff deficiency, or complex fractures. Unlike traditional total shoulder replacement where a ball is placed on the humerus and a socket on the glenoid, RSA reverses this configuration: a socket (glenosphere) is fixed to the scapula, and a ball (humeral component) is attached to the humerus. This design dramatically alters the shoulder's biomechanics, shifting the center of rotation medially and distally. This change allows the deltoid muscle to become the primary elevator and rotator of the arm, compensating for a non-functional rotator cuff. While revolutionary, this altered biomechanics also introduces specific movement limitations and risks.

The Primary Goal: Preventing Dislocation

The paramount concern post-RSA, especially in the early recovery phase, is preventing dislocation of the prosthetic joint. Due to the reversed ball-and-socket design, the implant is most vulnerable to dislocation when the arm is moved into specific positions that cause the humeral component to impinge against the inferior aspect of the glenosphere. This mechanical impingement can lever the humeral component out of the glenosphere, leading to a painful and potentially damaging dislocation.

Movements to Strictly Avoid (Acute Phase & Long-Term Considerations)

While specific restrictions and their duration will be guided by your surgeon and physical therapist, the following movements are generally contraindicated, particularly in the crucial initial weeks to months post-surgery, and often require long-term caution:

• Adduction with Internal Rotation and Extension (Hand Behind Back): This is the most critical movement to avoid. Reaching your hand behind your back (e.g., tucking in a shirt, reaching for a wallet in a back pocket) combines adduction (arm moving across the body), internal rotation, and extension (arm moving backward). This specific combination forces the humeral component to lever against the inferior aspect of the glenosphere, making it highly susceptible to dislocation.
• Extreme Internal Rotation: While some internal rotation is necessary for daily tasks, extreme internal rotation, especially when combined with adduction or extension, should be avoided. Activities like forcefully tucking a shirt into the back of pants or aggressive scratching of the opposite shoulder blade can be problematic.
• Excessive External Rotation (Especially Early On): While less common for dislocation in RSA compared to internal rotation, aggressive or unsupported external rotation can still strain the joint capsule, compromise soft tissue healing, or lead to subluxation, especially if the arm is also extended. Early post-op, external rotation is often limited to a neutral or slightly externally rotated position.
• Heavy Lifting and Carrying: Avoid lifting objects heavier than a specified weight (often 5-10 lbs initially) for several months. Overloading the joint can stress the implant-bone interface, compromise soft tissue repairs, and increase the risk of instability or failure.
• Sudden, Jerky, or Rapid Movements: Quick, uncontrolled movements can generate excessive forces on the joint, potentially leading to instability or injury. All movements should be slow, controlled, and deliberate.
• Reaching Across the Body (Especially Early Post-Op): While not always an absolute contraindication long-term, reaching far across the body can put the shoulder into a position of adduction and internal rotation, increasing risk. Be mindful of this movement, especially when combined with any resistance or speed.
• Impact Activities: Activities involving jarring or impact, such as contact sports, jumping, or aggressively pushing off with the arm, should be avoided due to the potential for implant loosening or fracture.

Why These Movements are Problematic (Biomechanics Explained)

The unique biomechanics of RSA are central to understanding these restrictions:

• Medialized Center of Rotation: The center of rotation is moved closer to the body, increasing the deltoid's lever arm and making it more efficient. However, this also changes the envelope of motion.
• Inferior Impingement Risk: With the glenosphere on the scapula and the humeral cup on the humerus, the most common mechanism of dislocation is inferior impingement. When the arm is adducted, internally rotated, and extended, the medial aspect of the humeral polyethylene liner (the plastic insert in the humeral component) can physically contact and lever against the inferior rim of the glenosphere. This leverage can then "lift" the humeral component out of its socket, causing dislocation.
• Deltoid Reliance: While the deltoid becomes the primary mover, it's also the only major muscle left to stabilize the joint in certain positions. Over-stressing it or moving into positions of mechanical disadvantage can compromise its ability to maintain joint congruency.

General Guidelines and Precautions

Beyond specific movements, adherence to broader guidelines is crucial:

• Follow Your Surgeon's Protocol: Every patient's recovery is unique. Your surgeon and physical therapist will provide a personalized protocol based on your specific surgery, bone quality, and progress. Adhere to these instructions meticulously.
• Listen to Your Body: Pain is a warning sign. Do not push through pain, as this can indicate excessive stress on the healing tissues or implant.
• Gradual Progression: Rehabilitation is a marathon, not a sprint. Progress through exercises and activities gradually, respecting tissue healing times and prosthetic stability.
• Avoid End-Range Movements: Especially in the early stages, avoid pushing your arm to its absolute maximum range of motion in any direction, even those not explicitly restricted, unless guided by your therapist.
• Maintain Scapular Stability: A strong and stable scapula (shoulder blade) provides a solid foundation for shoulder movement. Your physical therapy will emphasize exercises to strengthen the muscles that control the scapula.

The Role of Physical Therapy

Physical therapy is indispensable for a successful RSA recovery. Your physical therapist will:

• Educate You: Teach you safe movement patterns and how to perform daily activities without risking dislocation.
• Restore Range of Motion: Guide you through a carefully prescribed range of motion exercises to regain mobility within safe limits.
• Strengthen Appropriate Muscles: Focus on strengthening the deltoid and other periscapular muscles to enhance stability and function.
• Provide Proprioceptive Training: Help you regain awareness of your shoulder's position in space.

When to Seek Medical Advice

If you experience any of the following, contact your surgeon or medical team immediately:

• Sudden, severe pain in your operated shoulder.
• A popping or clunking sensation, especially if followed by pain or inability to move your arm.
• A visible deformity of the shoulder joint.
• Numbness or weakness in your arm or hand.
• Signs of infection such as fever, redness, warmth, or drainage from the incision site.

Understanding and adhering to these movement precautions is fundamental to a successful recovery and long-term function after reverse shoulder replacement. Your diligence in following medical advice will significantly contribute to the longevity and effectiveness of your new shoulder joint.