Shoulder Instability — A Physiotherapist’s Guide to Causes, Symptoms, and Rehabilitation
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The shoulder is one of the most versatile yet complex regions of the body — built for both strength and mobility. This page explores the anatomy of the shoulder, including its bones, joints, ligaments, muscles, tendons, nerves, and vascular structures, and how these components work together to provide stability and movement.
As this page develops, new internal links will connect directly to related articles linking this anatomy to some of the most common shoulder conditions, such as rotator cuff tears, supraspinatus injuries, shoulder impingement syndromes, and bursitis — all helping you understand both the structure and the clinical relevance of each area.
Whether you’re learning anatomy, recovering from injury, or simply curious about how the shoulder works, this evolving resource aims to make expert knowledge clear, accurate, and accessible.
In A Hurry? - Shoulder Instability Page Quick Links:
Understanding Shoulder Instability
What is Shoulder Instability?
The shoulder is the most mobile joint in the human body — and with that incredible range of movement comes a natural trade-off: stability. While this flexibility lets us reach, lift, throw, and rotate in multiple directions, it also makes the shoulder more prone to problems, especially when the supporting structures (like ligaments, labrum, or muscles) are weakened, overstretched, or injured.
Shoulder instability refers to a situation where the ball of the joint (the head of the humerus) moves too freely within its socket (the glenoid), and in some cases, slips out completely. This can result in a spectrum of issues — from occasional feelings of the joint "giving way" to full dislocations — often accompanied by pain, reduced confidence in movement, and a growing sense that something isn’t quite right.
The Shoulders Balancing Act
The shoulder joint is like a finely tuned machine — but one built for movement rather than brute stability. At its core, it’s a ball-and-socket setup: the ball is the rounded head of your upper arm bone (humerus), and the socket is the shallow glenoid cavity of the shoulder blade. Unlike the deep hip socket, the glenoid is relatively flat, which gives your shoulder its remarkable range of motion — but also means it relies on other structures to keep everything in place.
Think of the labrum — a raised, fibrous rim of cartilage around the socket — as a “booster seat” for the ball, adding depth and stability. Around this, a tight capsule, working like several guy ropes on a tent pole to stop the ball from drifting too far.
Then there are the muscles and tendons, particularly the rotator cuff, which act as dynamic stabilisers, constantly nudging and centering the humeral head as you move.
For many of my patients, this complex setup only becomes real once something goes wrong. They’ll often describe a moment of panic when reaching for a seatbelt or throwing a ball, feeling as though the shoulder is about to “pop out” — or worse, actually does. Others might not recall a big injury, but complain of a dull ache and a deep sense of weakness or mistrust in the joint.
The Shoulder joints, rotator cuff and connective tissue, viewed from the front
The Shoulder joints, rotator cuff and connective tissue, viewed from the back (the clavicles would joint in front of the ribs)
Causes of Shoulder Instability
Shoulder instability can develop gradually or happen suddenly, depending on the underlying cause. Broadly speaking, there are three main categories:
Structural or Congenital Factors
Some people are simply born with looser ligaments or a more “stretchy” joint capsule. This is sometimes referred to as hypermobility or laxity. In these cases, the shoulder can move more freely than it should — sometimes too freely. When instability occurs in more than one direction (e.g. forwards, backwards, and downwards), it’s called multidirectional instability (MDI).
This kind of instability isn’t caused by trauma — it’s often present from a young age and may be linked to conditions like generalised joint hypermobility (e.g. Ehlers-Danlos Syndrome or benign hypermobility syndrome). However, it can still cause pain, discomfort, and occasional “slipping” or “giving way” of the shoulder during movement.
Repetitive Overhead Activity
In people who do a lot of overhead movements — such as swimmers, throwers, gymnasts, or weightlifters — the shoulder capsule can gradually stretch out over time. This type of instability usually develops slowly and may not involve a specific injury.
It’s often referred to as acquired instability and can occur in just one direction (most often at the front of the shoulder, known as anterior instability). Common symptoms include a sense of looseness, shoulder fatigue, or a feeling that the shoulder is “about to pop out” during certain movements.
Trauma or Injury
A sudden injury, such as a fall onto an outstretched arm, a tackle in rugby, or a car accident, can cause the shoulder to dislocate. When this happens, structures like the labrum (a rim of cartilage that deepens the socket) and the surrounding ligaments often get damaged — particularly in the front of the joint.
This can lead to traumatic unidirectional instability, where the shoulder feels unstable or prone to repeat dislocations in one direction, typically anteriorly (forwards). This is the most common type of instability seen in younger athletes after a dislocation.
Other Contributing Factors
Poor muscle control (motor control deficits)
Even if the joint structure is intact, poor coordination or imbalance in the rotator cuff and scapular muscles can allow instability to develop.
Previous shoulder dislocations
Once the joint has dislocated, it’s more likely to happen again — especially in younger people. In fact this is the one time you want to be older! Those under 20 have a 70-90% chance or a recurrent dislocation, 20-30 years old that drops to 5-80% but you really want to be over the age of 40, where it drops to just 10%. Yay to being old.
Age and tissue quality
And within just a few lines, here is the anti age part again - In older individuals, tissues may become less elastic or more prone to damage, changing how the shoulder behaves after injury. So you may not re-dislocate, but you will probably have worse symptoms on the whole.
Symptoms of Shoulder Instability
Shoulder instability doesn’t always feel the same for everyone. Some people experience a single traumatic dislocation, while others live with vague but persistent symptoms that come and go. The signs can vary depending on the cause and severity, but common symptoms include:
Pain
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Often felt deep within the shoulder or around the front
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Typically worse during overhead activities, throwing, or reaching behind the back
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May occur after activity or persist at rest if the instability is significant
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Can be sharp, catching, or more of a dull ache depending on the underlying issue (e.g. labral tear vs muscular strain)
A feeling of looseness or “giving way”
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A sensation that the shoulder is about to pop out, especially during certain positions (like reaching out to the side or rotating the arm)
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May be described as feeling “unstable,” “wobbly,” or “not right” during movement
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In some cases, the shoulder may actually partially slip out and then relocate on its own — known as subluxation
Clicking, popping, or grinding
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Clicking or popping during motion can indicate abnormal joint mechanics or a labral injury
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Grinding sensations are less common but may occur if there’s damage to cartilage or bone from repeated dislocations
Visible signs after a dislocation
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Swelling and bruising may appear around the shoulder following a traumatic event
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In more severe cases, the shoulder may appear visibly deformed or out of place
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There may also be associated numbness or tingling down the arm if nerves are affected during dislocation
Muscle weakness or fatigue
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You may notice weakness when trying to lift the arm or perform overhead tasks
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The rotator cuff and stabilising muscles often struggle to control the joint if instability is present
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Fatigue can set in quickly with repetitive or weight-bearing shoulder use
Muscle weakness or fatigue
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For some people, especially younger athletes, instability leads to repeat episodes
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The more often it happens, the more likely it is to occur again — particularly if the labrum or capsule is damaged and not fully rehabilitated
If you're experiencing any of these symptoms — especially if they've been ongoing or worsening — it’s worth getting a proper assessment. Early treatment can often prevent long-term issues and reduce the risk of further dislocations.
Diagnosing Shoulder Instability
Getting an accurate diagnosis is the first and most important step toward effective treatment. Because shoulder instability can come from a variety of causes — and affect people in very different ways — your assessment needs to be careful, thorough, and tailored to you.
Personally as a practitioner, the diagnostic process is designed to make sure I understand not just what’s wrong, but also why it’s happened — and how best to fix it.
Listening to your story (Medical history)
We start with a detailed conversation. You’ll be asked questions like:
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When did your symptoms start — was there a specific injury or did it come on gradually?
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What kinds of movements cause pain, or make the shoulder feel unstable?
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Have you ever had the shoulder pop out or "slip" before?
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Do you do any sports or activities that involve a lot of overhead movement (e.g. swimming, weights, tennis)?
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Do you have a history of shoulder dislocations, surgeries, or other joint issues?
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Is there any history of joint hypermobility in your family?
This part isn’t just “form-filling” — it’s often the most useful clue to what’s really going on. If you see a practitioner who jumps right in to treatment and puts you on machine, does not put hands on you, or, where possible expose at least the shoulder and shoulder blade as appropriate to look at what happens when you move, I would question the ability to accurately diagnose. especially if I was paying privately!! (this may be different in primary care or NHS settings during the triaging process)
Hands-on physical assessment
Next, we examine how your shoulder is moving, functioning, and responding to load. This may include:
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Palpation: Feeling the shoulder and surrounding muscles for tenderness, swelling, joint position, or unusual movement
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Range of motion testing: Checking how far your shoulder can move — both passively (we move it for you) and actively (you move it yourself)
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Muscle strength testing: Assessing the power and endurance of key stabilising muscles, especially the rotator cuff and scapular muscles
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Stability testing: Gently moving your arm into specific positions to see if it causes discomfort, fear, or a sensation of “giving way”
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For example, tests like the apprehension test, relocation test, and drawer tests can help identify whether the joint is unstable and in which direction (e.g. forwards or backwards)
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Functional observation: Watching how your shoulder moves during everyday tasks — like reaching overhead or lifting — and checking for protective patterns or compensation. In a joint as mobile as the shoulder you really cannot understand the joint without looking at how it moves - no matter how good you are.
If you’ve had a previous dislocation, these tests help determine whether the joint has fully healed or is still vulnerable to slipping out again.
Imaging (if necessary)
In many cases, clinical testing alone is enough to make a confident diagnosis. But if we suspect structural damage — or if your symptoms are complex or persistent — further imaging may be recommended.
Here’s what each type of scan can tell us:
X-rays
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Why? To check for bone damage, previous fractures, or abnormal joint shapes (like a shallow socket) that might contribute to instability
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What to expect: A quick, non-invasive procedure — you may be asked to hold your arm in a few positions while the technician takes images
MRI (Magnetic Resonance Imaging)
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Why? To see the soft tissues in high detail — including the labrum, ligaments, joint capsule, tendons, and muscles
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What it shows: Whether you’ve torn your labrum (e.g. a Bankart lesion), stretched the capsule, or irritated nearby tissues
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What to expect: You’ll lie on a table inside a scanner for around 30–60 minutes. It’s painless, but the machine can be loud. Some people may feel a little claustrophobic — just let us know in advance
CT scan
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Why? If we need a clearer 3D view of the bony structures — especially if you've had repeat dislocations or are considering surgery
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What to expect: Similar to an MRI, but quicker. You’ll lie still for just a few minutes while the scanner rotates around you
Ultrasound
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Why? To examine muscles and tendons in real time, especially during movement. Useful for identifying dynamic instability
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What to expect: A handheld probe and some gel are used to glide over your shoulder — it’s quick, non-invasive, and often done during your appointment
What happens next?
After the assessment is complete — including a detailed history, physical examination, and any necessary scans — the findings are carefully reviewed to confirm the diagnosis and identify the likely cause of the instability.
Clear explanations are essential at this stage. Most patients benefit from understanding:
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What’s going on with the shoulder
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Why it’s behaving this way
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Which treatment options are likely to be most effective
The approach to treatment depends on the nature of the instability:
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If the issue is mainly due to muscle imbalance or poor joint control, a focused rehabilitation programme may be all that’s needed
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If the instability is caused by structural damage, such as a torn labrum or stretched joint capsule, further steps — like advanced imaging, joint injections, or a surgical opinion — may be considered
The goal is always to develop a treatment plan based on the individual's specific needs — avoiding unnecessary interventions while addressing the root cause of the problem.
Treatment Options
The primary aim of treatment is to restore shoulder stability, function, and confidence — ideally without repeat dislocations or long-term limitations. The right approach depends on several factors, including:
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The cause of instability (traumatic vs. atraumatic)
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Whether it’s a first-time or recurrent dislocation
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The direction of instability (anterior, posterior, or multidirectional)
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The presence of soft tissue or structural damage (e.g. labral tear)
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The individual’s age, activity levels, goals, and overall health
Treatment typically falls into two main categories: conservative (non-surgical) and surgical. Many people improve with conservative care alone.
Initial management of acute dislocation
For a first-time traumatic dislocation, immediate care may involve:
Closed reduction:
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A trained clinician repositions the dislocated shoulder joint, usually under sedation or anaesthesia
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This should be followed by assessment for associated injuries (e.g. labral tear, Hill-Sachs lesion)
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Post-reduction imaging (X-ray or MRI) may be used to confirm proper alignment and check for damage
Pain relief and inflammation control:
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Short-term use of NSAIDs (e.g. ibuprofen) or paracetamol can help reduce pain and swelling
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Cold therapy (e.g. ice packs for 15–20 minutes, several times daily) may help in the early stages
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In selected cases, a corticosteroid injection may be considered for persistent inflammation, though this is not routine
Immobilisation:
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A sling may be used for a brief period (typically 1–3 weeks), especially in younger patients with traumatic instability
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Prolonged immobilisation is generally avoided, as it may delay rehabilitation or lead to stiffness
Evidence insight: Studies show that early rehab after a short period of immobilisation leads to better outcomes than prolonged rest alone — particularly in first-time dislocations
Rehabilitation (conservative treatment)
Most cases of shoulder instability — especially atraumatic or multidirectional types — can be managed effectively with a structured rehabilitation programme.
Key components include:
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Motor control retraining: Helping the shoulder muscles (especially the rotator cuff and scapular stabilisers) work together to keep the joint centred and stable
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Strengthening exercises: Focused on the shoulder girdle, scapula, and trunk to build control and endurance
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Proprioceptive training: Exercises that improve joint awareness and reduce the risk of future dislocations
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Progressive loading: Gradually restoring movement and strength in meaningful positions (e.g. overhead, throwing)
This process is typically guided by a physiotherapist with expertise in shoulder conditions. It may take 8–16 weeks to see significant improvements, though this varies by individual.
Evidence insight: Research supports rehab as the first-line treatment for many forms of instability, particularly in non-traumatic and multidirectional cases.
Surgical treatment (when indicated)
Surgery is generally considered when:
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There have been recurrent dislocations despite conservative care
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There is clear evidence of labral or capsular damage (e.g. Bankart lesion)
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The person is young, active, and involved in contact or overhead sports
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There is significant bone loss or a bony Bankart/Hill-Sachs lesion
Common procedures include:
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Arthroscopic stabilisation (Bankart repair) – repairing the torn labrum and tightening the joint capsule
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Latarjet procedure – transferring bone and tendon to reinforce the front of the socket in cases of significant bone loss
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Capsular shift or plication – tightening the loose joint capsule (often used in multidirectional instability)
While national guidelines help define which surgical options are appropriate for different types of shoulder instability, the final recommendation often depends on the individual surgeon’s experience, skillset, and preferred techniques.
Ongoing support and prevention
Long-term management may include:
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Education and self-management strategies – understanding movement limits, safe return to sport, and flare-up management
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Lifestyle modifications – temporary avoidance of high-risk activities during rehab
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Tailored maintenance exercises – to preserve strength, control, and joint health over time
For those with underlying hypermobility syndromes, joint protection strategies and whole-body conditioning may also be recommended.
Shoulder Instability – Summary
Shoulder instability occurs when the structures that normally keep the shoulder joint securely in place become weakened, stretched, or damaged. This can lead to a feeling that the shoulder is loose, slips out of place, or even dislocates entirely. For some people, it happens after a sudden injury; for others, it develops gradually over time due to repetitive movements or naturally looser joints.
Common symptoms include:
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A feeling of the shoulder “giving way” or slipping
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Pain during certain movements, especially overhead
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Clicking, popping, or grinding in the joint
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Weakness or reduced control
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Repeated dislocations or subluxations
Causes can range from:
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Traumatic injuries, such as falls or sports collisions
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Repetitive strain, particularly from overhead sports or work
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Congenital joint laxity, where the shoulder is naturally more mobile
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Poor muscle control or previous dislocations
Diagnosis involves:
A detailed consultation and physical assessment, supported by imaging (e.g. X-rays, MRI, ultrasound) if needed. Key diagnostic tools include stability tests, strength testing, and range of motion checks to determine the type and direction of instability.
Treatment options include:
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Initial management after dislocation (e.g. reduction, rest, pain relief)
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Structured rehabilitation, often very effective in improving control and reducing recurrence
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Surgical procedures in cases of structural damage or ongoing instability, including Bankart repair, Latarjet, or capsular shift
Treatment decisions are based on the type of instability, the structures involved, activity demands, and the individual’s goals. National guidelines help guide the process, but the final approach may vary depending on the expertise and preferences of the treating surgeon or clinician.
The goal of treatment is simple:
To help you regain confidence, control, and comfort in your shoulder — whether that’s returning to sport, lifting at work, or simply moving without worry.
A Quick Note From Chris
It won’t surprise many of you to know that I don’t get any financial reward for writing and sharing these pages. I do it because I genuinely want to help people better understand their conditions and feel more in control of their recovery.
All I ask is that you don’t plagiarise or claim this work as your own — and if you’ve found it helpful, please consider sharing it with friends, family, or anyone else who might benefit from it. Follow my blog for regular updates on new topics, pages and future projects.
Thanks for reading — and for taking your health seriously.
Shoulder Instability FAQ's
What is shoulder instability?
Shoulder instability occurs when the ligaments, capsule, or muscles that normally keep the shoulder joint stable become stretched or damaged. This can make the joint feel loose or allow it to partially or fully dislocate.
What causes shoulder instability?
The most common causes include traumatic shoulder dislocations, repetitive overhead movements (such as throwing or swimming), and generalised ligament laxity. Weakness in the rotator cuff or scapular muscles can also contribute to instability over time.
What are the symptoms of shoulder instability?
Typical symptoms include a sensation of the shoulder “slipping out,” weakness when lifting the arm, clicking or clunking sounds, and pain during overhead activities. Some people experience repeated dislocations or a constant feeling of insecurity in the joint.
How is shoulder instability treated?
Treatment usually begins with physiotherapy, focusing on restoring control and strength in the rotator cuff and scapular stabilisers. Manual therapy and specific exercise programmes can reduce pain and improve stability. In severe or recurrent cases, surgical stabilisation may be considered, followed by guided rehabilitation.
How long does recovery from shoulder instability take?
Recovery varies depending on the severity and cause. Mild instability may improve in a few weeks with consistent physiotherapy, while post-surgical or recurrent dislocations can take several months to fully stabilise. Adherence to a structured rehab plan is key.
Can shoulder instability return after treatment?
Yes — recurrence is possible, especially if the underlying cause (like muscle imbalance or ligament laxity) isn’t fully addressed. Ongoing strength and control exercises help prevent future instability episodes.
When should I see a physiotherapist?
If you experience frequent shoulder slipping, weakness, or pain after dislocation, you should seek a professional assessment. Early diagnosis helps prevent further damage and supports faster, safer recovery.
Can physiotherapy help after shoulder dislocation surgery?
Absolutely. Post-surgical physiotherapy focuses on regaining movement, reducing stiffness, and rebuilding muscular control to protect the repaired structures and restore normal shoulder function.
Should I avoid exercise with an unstable shoulder?
Avoid activities that trigger pain or instability, especially overhead or contact sports, until a physiotherapist has assessed your shoulder. Gradual, guided strengthening is safer and more effective than avoiding exercise entirely.
What’s the difference between shoulder instability and rotator cuff injury?
Shoulder instability involves the joint moving excessively due to laxity in ligaments or capsule, whereas rotator cuff injuries affect the tendons that support and move the joint. The two conditions often overlap and may occur together.
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