An anterior shoulder dislocation occurs when the head of the humerus is forcibly displaced forward out of the glenoid fossa (shoulder socket). This injury accounts for the vast majority of all shoulder dislocations, typically resulting from a fall onto an outstretched arm or a forceful blow. Reduction, the process of manually guiding the humeral head back into the socket, is a serious medical procedure. This information is for educational purposes only; a shoulder reduction must always be performed by a trained medical professional, such as a physician, emergency medical technician, or certified athletic trainer.
The Critical Need for Medical Evaluation
Before any attempt at reduction, a thorough medical assessment is necessary to identify potential complications. Because major blood vessels and nerves are close to the shoulder joint, neurovascular status must be checked immediately. The axillary nerve is the most frequently injured structure, tested by checking for sensation over the lateral deltoid muscle and the patient’s ability to contract the deltoid.
A provider must also check distal circulation by assessing the patient’s pulse, color, and temperature of the hand to rule out vascular compromise. An inability to move the wrist or fingers may indicate more extensive injury to the brachial plexus. Reduction must be avoided if a fracture is suspected, such as a large greater tuberosity or glenoid rim fracture, or if the dislocation is open. Manipulation in these cases could cause further damage, requiring immediate referral to an orthopedic surgeon.
Preparation and Patient Comfort
Successful reduction relies on overcoming the intense muscle spasm that occurs as soft tissues attempt to stabilize the unstable joint. This protective muscle tightening acts against the reduction maneuver, making the procedure painful and prone to failure. Muscle relaxation is a primary goal of the preparation phase.
In a clinical environment, relaxation is often achieved through procedural sedation and analgesia (PSA), using intravenous agents like propofol or etomidate. An alternative is an intra-articular injection of a local anesthetic, such as lidocaine, directly into the joint space.
For patients in an emergency or remote setting, distraction techniques coupled with verbal guidance and gentle massage of the shoulder muscles can sufficiently fatigue the spasms to allow for a less forceful reduction. Patient positioning is specific to the technique chosen, requiring the patient to be either supine or prone.
Overview of Common Reduction Techniques
The goal of all modern reduction techniques is to use minimal force and leverage muscle fatigue or anatomical pathways to gently guide the humeral head back into the glenoid socket.
The Traction-Countertraction technique employs a sustained pull in opposite directions to distract the humeral head from the glenoid rim. It requires two operators, or one operator using a sheet wrapped around the chest for countertraction, while the second applies axial traction to the arm. The slow, steady pull fatigues the powerful shoulder muscles, allowing the humeral head to slip back into position once muscle tension subsides.
The External Rotation Method is a low-force technique that capitalizes on the anatomy of the joint and the surrounding ligaments. With the patient supine and the elbow bent to 90 degrees, the operator slowly rotates the arm outward. This rotation unwinds the anterior joint capsule and the subscapularis tendon, allowing the humeral head to re-center itself without significant traction force.
The Stimson Technique relies on gravity and sustained weight to achieve spontaneous reduction. The patient is placed prone with the affected arm dangling over the side. A weight (typically 5 to 10 pounds) is secured to the wrist or forearm, providing constant, gentle downward traction. The sustained pull fatigues the muscles over 15 to 30 minutes, and the humeral head often reduces without further manual manipulation.
Post-Reduction Management
Immediately following a successful reduction, often signaled by a palpable “clunk” and instant relief of pain, a repeat neurovascular examination is mandatory. The clinician must confirm that nerve and vascular function, which may have been compromised by the dislocation, has returned or has not worsened.
Post-reduction imaging, typically X-rays, is performed next to confirm the humeral head is fully seated and to check for any associated fractures missed initially. Once confirmed, the shoulder is immobilized in a sling or immobilizer for one to three weeks. Many protocols favor a shorter immobilization period to prevent joint stiffness, especially in older patients. After this brief period of rest, a structured physical therapy program is initiated to restore range of motion, strengthen the rotator cuff muscles, and stabilize the joint.