The glenohumeral joint (GH) is a ball and socket joint that includes a complex, dynamic, articulation between the proximal humerus (“ball”) and the glenoid (“socket”) of the scapula. The static and dynamic stabilizing structures allow for extreme range of motion in multiple planes, that predisposes the joint to instability events. Shoulder instability often occurs when the capsule (lining of the shoulder joint), ligaments, or labrum becomes stretched, torn, or detached from the glenoid, commonly after shoulder trauma or repetitive motion. A genetic condition can also cause looseness and weakness in the joint. Exercise programs that aim to strengthen the rotator cuff and scapular muscles are often the primary treatment for instability, where full range of motion usually returns after 6-8 weeks.
Anatomy
Structurally a ball and socket joint, that involves the humeral head with the glenoid cavity of the scapula, and it represents the major articulation of the shoulder girdle. The joint capsule and ligaments provide a passive restraint to keep the humeral head compressed against the glenoid. As one of the most mobile joints, the GH joint has stabilising elements, that are divided into static (capsule-labro-ligamentous complex) and active (rotator cuffs and bicep tendons).
Symptoms
The symptoms of Glenohumeral Joint Instability include but may not be limited to:
- Pain, tenderness, swelling, and/or bruising.
- A loose feeling, or hearing a “pop” in the shoulder joint.
- Repeated shoulder dislocation.
- Tingling or burning sensation in the lower arm and hand.
- Localised numbness of the skin overlying the deltoid muscle.
- Decreased range of arm/shoulder motion.
Causes
Glenohumeral joint instability can occur following a traumatic accident such as a fall or collision. It can also occur without significant trauma or injury, which is often genetic from those with hypermobility or connective tissue problems, or from a development of laxity in tissues of the shoulder joint. Other causes can be from repetitive motions, particularly from throwing sports, causing the shoulder to stretch over time, where normal muscle control is lost.
Diagnosis
A physical examination can confirm the impression obtained from the history and help to determine if the shoulder is loose or unstable. Radiographs or imaging, such as X-rays, MRI, or a CT scan can help to provide confirmation of traumatic glenohumeral instability present from the damaged bones, cartilage, and rotator cuff. Mobility may be restricted for two weeks, followed by physical therapy to strengthen the muscles that stabilises the shoulder.
Classifications
Polar Type I (structural instability) – typically present with a positive apprehension (anterior direction) associated with rotator cuff weakness. Posture, single leg balance, and scapula control are often disturbed. Can begin to exhibit signs of poor scapula control, abnormal muscle activation, and altered trunk stability and balance, when moving towards type II and III poles.
Polar Type II – (atraumatic instability) – present with positive anterior apprehension test, with increased laxity and excessive external rotations, and muscular balance
Polar Type III – (neurological dysfunctional or muscle patterning) – shows abnormal activation of large muscles and suppression of the rotator cuff. Mostly occurs with a history of easy shoulder dislocation.
Treatment
Treatment usually begins with physical therapy, designed to strengthen the shoulder, and maintain the joint in position.
Restricting activity that includes overhead motion may be advised to reduce symptoms. Full range of motion usually returns after 6-8 weeks.
If less invasive treatments don’t work, and in severe instances, open surgery is often necessary, where an incision is made over the shoulder and the muscles are moved to access the joint capsule, ligaments, and labrum. After surgery, full recovery often takes 4-6 months, and in some cases up to 12 months. At this stage some deep tissue massage and scar tissue work may be necesary!
Exercises
1. Shoulder Flexion (Lying Down)
- Purpose: Improve shoulder mobility and strengthen the muscles involved in flexion, which helps stabilise the shoulder joint.
- How to Perform:
- Lie on your back with your arm by your side.
- Hold a light weight or no weight at all, and slowly raise your arm straight up toward the ceiling, keeping your elbow straight.
- Lower your arm back down slowly, and repeat.
2. Shoulder Blade Squeeze
- Purpose: Strengthen the scapular stabilisers, particularly the muscles that control the shoulder blades, to improve overall shoulder stability.
- How to Perform:
- Sit or stand with your arms at your sides.
- Squeeze your shoulder blades together, as if trying to pinch something between them.
- Hold the squeeze for a few seconds, then relax.
- Repeat for the desired number of repetitions.
3. Resisted Rows
- Purpose: Strengthen the upper back and shoulder muscles, particularly the rhomboids and middle trapezius, to enhance shoulder stability.
- How to Perform:
- Anchor a resistance band at chest height.
- Hold the band with both hands, and step back to create tension.
- Pull the band toward your chest, keeping your elbows close to your sides and squeezing your shoulder blades together.
- Slowly return to the starting position and repeat.
4. Internal Rotator Strengthening Exercise
- Purpose: Strengthen the internal rotators (subscapularis) of the shoulder, which are crucial for maintaining joint stability.
- How to Perform:
- Attach a resistance band to a sturdy object at waist height.
- Stand with your affected side closest to the band, holding the other end with your elbow bent at 90 degrees.
- Keep your elbow close to your body, and rotate your arm inward against the resistance.
- Slowly return to the starting position and repeat.
5. External Rotator Strengthening Exercise (with Arm Abducted 90°)
- Purpose: Target the external rotators (infraspinatus and teres minor) to improve the stability and control of the shoulder joint.
- How to Perform:
- Stand or sit with your arm raised to shoulder height and your elbow bent at 90 degrees, holding a resistance band or light weight.
- Rotate your forearm upward, keeping your elbow in line with your shoulder.
- Slowly lower your arm back down to the starting position and repeat.
6. Standing Row (with Resistance Band)
- Purpose: Strengthen the muscles that stabilise the shoulder, particularly the upper back and shoulder blade muscles, to improve shoulder joint stability.
- How to Perform:
- Anchor a resistance band at chest height.
- Stand facing the band, holding it with both hands.
- Pull the band toward your chest, leading with your elbows and squeezing your shoulder blades together.
- Slowly return to the starting position and repeat.
Prevention
Glenohumeral Joint Instability (GJI) is a condition that occurs when the ball and socket joint of the shoulder become dislocated or partially dislocated due to trauma or other underlying conditions. GJI can result in pain, weakness, and limited range of motion, making it difficult for people to perform their daily activities. In severe cases, surgery may be required to treat the condition. However, prevention is always better than cure, and there are several steps that individuals can take to prevent GJI.
Strengthen the Rotator Cuff Muscles:
The rotator cuff muscles are a group of muscles that attach the shoulder blade to the humerus bone and help stabilize the shoulder joint. Strengthening these muscles can help prevent GJI. Exercises that target the rotator cuff muscles include external and internal rotation exercises, scapular stabilization exercises, and shoulder blade squeezes.
Improve Shoulder Mobility:
Limited shoulder mobility can lead to increased stress on the shoulder joint, which can increase the risk of GJI. Stretching exercises that target the shoulder joint, such as shoulder circles and shoulder flexion stretches, can help improve shoulder mobility and prevent GJI.
Maintain Good Posture:
Poor posture can contribute to shoulder instability and increase the risk of GJI. Individuals should aim to maintain good posture by keeping their shoulders back and down and their chest open. Practicing good posture can help improve shoulder alignment and stability.
Avoid Overuse Injuries:
Overuse injuries can cause wear and tear on the shoulder joint, leading to increased instability and a higher risk of GJI. To avoid overuse injuries, individuals should practice proper form and technique when performing exercises and avoid repetitive overhead movements.
Wear Proper Protective Gear:
Individuals who participate in contact sports or activities that involve the risk of shoulder injuries should wear proper protective gear, such as shoulder pads or braces. Protective gear can help absorb the impact of a fall or collision, reducing the risk of GJI.
In conclusion, preventing GJI requires a combination of strengthening exercises, stretching, good posture, injury prevention strategies, and protective gear. By following these steps, individuals can help reduce the risk of GJI and maintain a healthy and stable shoulder joint. It is important to consult with a healthcare professional before starting any new exercise program or if experiencing any shoulder pain or discomfort. If you are unsure what to do, please contact us and one of our Personal Trainers or Sports Therapists can help.