Understanding Hemiplegic Shoulder Subluxation (HSS)
Hemiplegic shoulder subluxation (HSS) is a highly prevalent complication affecting stroke survivors, particularly during the flaccid stage of recovery. The glenohumeral joint is naturally highly mobile but inherently unstable, relying heavily on the active contraction of the rotator cuff muscles and the deltoid to maintain joint integrity. Following a stroke, the onset of hemiplegia leads to flaccidity and weakness in these key muscle groups.
Without active muscular support, the weight of the affected arm, combined with the downward pull of gravity, stretches the joint capsule and surrounding ligaments. This causes the humeral head to slip downward and outward from the glenoid fossa. This displacement not only limits functional recovery during neuro-rehabilitation but can also cause microtrauma, severe pain, and secondary complications like Complex Regional Pain Syndrome (CRPS).
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The Clinical Mechanics of Joint Laxity
In a healthy shoulder, the humeral head is held against the glenoid cavity by a passive locking mechanism, which is maintained by the horizontal alignment of the clavicle and scapula, and active dynamic stability provided by the muscles.
Post-stroke HSS is driven by two main pathological factors:
- Muscle Flaccidity: Loss of tone in the supraspinatus and posterior deltoid removes the upward pull needed to keep the humerus seated in the socket.
- Scapular Malalignment: The scapula often rotates downward, tilting the glenoid fossa vertically and allowing the humeral head to slide down the lateral wall of the thorax.
Rehabilitation must therefore target both shoulder muscles and scapular positioning to restore joint biomechanics.
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The Role of Support and Technology
Therapists utilize a combination of orthotics, taping, and electrical stimulation to manage HSS while the patient regains voluntary motor control.
1. Supportive Slings
Traditional slings that immobilize the arm in a flexed, adducted position can promote spasticity and joint contractures. Modern alternatives, like the GivMohr sling, support the humeral head without restricting movement or forcing the arm into a flexed posture. Slings are typically recommended during upright ambulation and transfers but should be removed during exercise.
2. Functional Electrical Stimulation (FES)
FES is a critical technology in neuro-rehabilitation. By applying electrical currents to the supraspinatus and posterior deltoid muscles, FES induces muscle contraction, actively drawing the humeral head back into the glenoid cavity. This prevents tissue elongation and promotes motor re-education.
3. Kinesiology Taping
Elastic taping provides proprioceptive feedback, encouraging alignment and activating the surrounding muscles to support the joint capsule.
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Clinically Recommended Hemiplegic Shoulder Subluxation Exercises
All exercises must be performed within a pain-free range of motion. Avoid pulling on the flaccid arm, and do not use overhead pulley systems, which can pinch the rotator cuff tendons against the acromion.
1. Isometric Shoulder Abduction
- How-to: Stand or sit beside a wall with the affected elbow bent to 90 degrees. Place a small pillow between the elbow and the wall. Gently press the elbow outward against the wall/pillow. Hold for 5–10 seconds. Repeat 10 times.
- Goal: Safely activate the deltoid muscle without causing joint displacement.
2. Scapular Squeezes (Retraction)
- How-to: Sit upright with arms resting comfortably on the lap or on a table. Gently squeeze the shoulder blades together, focusing on pulling them down and back. Hold for 5 seconds. Repeat 15 times.
- Goal: Realign the scapula to restore the glenoid fossa's natural supportive angle.
3. Table Slides (Active-Assisted Flexion)
- How-to: Sit at a table. Place a towel under both hands (fingers can be interlocked). Slide both hands forward across the table, leaning the torso forward slightly to assist the movement. Slowly slide back. Repeat 10–12 times.
- Goal: Regain shoulder flexion without vertical gravity loading.
4. Closed-Chain Weight Bearing
- How-to: Sit on a firm surface. Place the affected hand flat on the seat next to the hip, with fingers pointed slightly outward. Extend the elbow and lean the body weight slightly onto the affected arm. Hold for 20–30 seconds. Repeat 5 times.
- Goal: Provide joint approximation and proprioceptive feedback to stimulate muscle activation.
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Comparison of HSS Management Strategies
| Strategy | Primary Mechanism | Pros | Cons |
|---|---|---|---|
| **Functional Electrical Stimulation (FES)** | Active motor recruitment, vertical joint approximation | Directly retrains weak muscles, reduces subluxation actively | Requires specialized equipment, skin irritation risks |
| **GivMohr / Supportive Slings** | Passive biomechanical support against gravity | Essential during early ambulation and transfers to prevent stretching | Does not actively build muscle strength, can limit active use |
| **Isometric Strengthening** | Voluntary motor unit activation without joint movement | Safe for joint capsule, builds early muscle tone | Limited range of motion training |
| **Weight-Bearing exercises** | Joint approximation and proprioceptive loading | Stimulates joint receptors, stabilizes scapula | Requires sufficient wrist/elbow stability to perform safely |
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Crucial Handling and Care Precautions
Caregivers and healthcare staff must be educated on proper handling. Never pull on the patient's hemiplegic arm to assist them in standing, sitting, or turning in bed. This traction force on an unsupported joint can instantly cause or worsen a subluxation. When transferring, support the patient by the trunk or pelvis, keeping the affected arm close to their body.