Cracking the Code of Frozen Shoulder: What You Need to Know
Imagine waking up one morning and realising you can no longer lift your arm without sharp pain or stiffness. What if simple tasks like reaching for a shelf or combing your hair became frustratingly difficult? This is the reality for those suffering from adhesive capsulitis or commonly known as frozen shoulder.
Frozen shoulder is a condition that sneaks up on people, causing pain and significantly limiting shoulder movement over time. But it’s more than just an inconvenience—it’s a debilitating issue that can severely affect daily life. Understanding how it develops and how to manage it is key to helping people regain their mobility.
In this article, we’ll discuss what frozen shoulder really is, explore how it evolves through different stages, and share effective assessment and treatment strategies. This article is guided by the amazing people who did the research and from years of clinical experience.
Keep reading to learn how to treat Frozen shoulder!
In a Nutshell:
Frozen shoulder is a condition characterised by a gradual increase in shoulder pain and a significant reduction in range of motion, both actively and passively. It progresses over time and typically resolves within 18–24 months, although some cases may last longer.
Key Points:
- Symptoms:Gradual onset of shoulder pain, loss of range of motion, particularly in external rotation and flexion.
- Stages:Freezing (painful), Frozen (stiffness), Thawing (recovery).
- Common Causes:Linked to inflammation, diabetes, thyroid disorders, and hormonal imbalances. More frequent in women, especially during menopause.
- Conservative Treatment:Focus on pain management (NSAIDs, corticosteroid injections) and gentle physiotherapy. Early intervention is importnat.
- Surgical Options:Considered when conservative measures fail, such as arthroscopic capsular release or manipulation under anaesthesia
Frozen Shoulder – What Is It?
Adhesive capsulitis, commonly known as frozen shoulder, is described in current practice guidelines as a type of condition that tends to get worse over time.
Interestingly, no other joint in the body has the same sequence of symptoms or presentation which makes this condition unique.
Frozen shoulder is characterised by:
- Gradual increase of pain
- Reduction of range of motion (passively and actively)
In other words, people with adhesive capsulitis experience a combination of pain and a noticeable decrease in how far they can move their shoulder on their own and when someone else helps move it.
What Structure Causes Frozen Shoulder?
For quite some time, researchers have suggested that an area in the shoulder called the ‘rotator interval,’ along with the ‘coracohumeral ligament’ kickstart the process that leads to frozen shoulder. As the condition progresses and symptoms change, other joint capsule parts become involved.
Did you know?
- Painful and limited shoulder movement was 1st recognised as a distinct clinical issue in 1872, when Duplay referred to it as scapulo-humeral periarthritis.
- In 1934, Codman introduced the term frozen shoulder, a term still used today.
- By 1945, the term adhesive capsulitiswas introduced to describe the thickening of the glenohumeral joint capsule, which leads to stiffness in the shoulder.
- Adhesive capsulitis is estimated to affect between 2% and 5% of the general population, with women experiencing it more often than men.
Anatomy Of The Shoulder
Rotator interval
Rotator interval refers to 2 triangular spaces that are like “gaps” within the rotator cuff.
- The anterior rotator interval is the bigger triangle. It’s positioned between the subscapularis and supraspinatus tendons.
- The posterior rotator interval is the smaller triangle between the supraspinatus and infraspinatus tendons.
It borders the lower part of the subscapularis muscle, the upper front part of the supraspinatus muscle, and the base of the coracoid process. Inside this space, you’ll find the long head of the biceps tendon.
- The ‘roof’ of this space is formed by the coracohumeral ligament, the superior glenohumeral ligament, and the covering of the rotator interval.
- The ‘floor’ is the smooth cartilage on the upper part of the humerus bone. There’s a small fat pad called the subcoracoid fat triangle that fills the gap between the covering of the rotator interval and the coracoid process.
In the simplest way possible, the rotator interval is a triangle-shaped space in the shoulder that contains important tissues like tendons and ligaments. It provides the shoulder with stability and support. If strength or integrity is affected, it can lead to shoulder stiffness and instability.
Coracohumeral ligament:
The coraco-humeral ligament starts from the outer base of the coracoid process and has two parts.
- One attaches to the front of the supraspinatus tendon and greater tuberosity of the humerus.
- The other connects to the upper subscapularis fibers, transverse humeral ligament, and lesser tuberosity.
It helps to prevent excessive inward movement of the humerus during raising and outward rotation of the arm, becoming tighter in those positions to stabilise the shoulder. It relaxes when the arm is lowered and rotated inward.
Shoulder capsule:
The shoulder joint capsule is a fibrous sleeve that surrounds and encases the humeral head and the glenoid cavity (part of the scapula). It provides stability to the joint by holding the structures in place stopping excessive movement and helping to prevent dislocations.
Histology
In the early stages of adhesive capsulitis, the shoulder undergoes changes that trigger the sensation of discomfort.
Increased blood flow and tissue growth occur in the joint lining (synovium), causing swelling and the increased production of cells called fibroblasts. This process also triggers the formation of new nerve fibers around small blood vessels.
These new nerves develop due to a molecule known as nerve growth factor receptor p75. Along with this nerve growth, inflammatory substances in the body make certain pain channels more sensitive to acid, increasing pain sensitivity (hyperalgesia).
What Causes The Tissue Stiffening In Frozen Shoulder?
To make this simple let’s get some definitions out of the way:
- Fibroblast = “A fibroblast is a type of cell that contributes to the formation of connective tissue, a fibrous cellular material that supports and connects other tissues or organs in the body. Fibroblasts secrete collagen proteins that help maintain the structural framework of tissue.”
- Collagen = “Collagen is the most abundant protein in the body. Its fiber-like structure is used to make connective tissue.”
- TGF-β1 = “The TGFβ-1 protein triggers chemical signals that regulate various cell activities inside the cell, including the growth and division (proliferation) of cells, the maturation of cells to carry out specific functions (differentiation), cell movement (motility), and controlled cell death (apoptosis)”
- Myofibroblasts = “Myofibroblasts are contractile, α-smooth muscle actin-positive cells with multiple roles in pathophysiological processes. Myofibroblasts mediate wound contractions, but their persistent presence in tissues is central to driving fibrosis, making them attractive cell targets for the development of therapeutic treatments”
Fibroblasts are the main cells responsible for tissue health and adaptation, however, sometimes the body can go overboard.
Let me explain,
Fibroblasts are responsible for producing collagen, which is important for tissue structure. However, they can also cause contraction in the surrounding environment. A molecule called transforming growth factor-beta 1 (TGF-β1is the main contributor in this process – it helps fibroblasts become more specialised, turning them into myofibroblasts. This transformation increases collagen production, which can make tissues stiffer.
However, tissue stiffness isn’t only caused by chemical signalling, it’s also caused by physical stress. Fibroblasts can ‘feel’ this stress through their internal structure.
They need a certain level of stress to turn into myofibroblasts. Mechanical stress can activate hidden TGF-β1, adding to tissue stiffness. Both mechanical stress and TGF-β1 are closely connected and important factors in tissue stiffness.
Tissue stiffness isn’t just a result of chemical signals from TGF-β1; it’s also influenced by physical “stress”. Fibroblasts can sense this stress through their internal structure, and they need a certain amount of it to transform into myofibroblasts.
This mechanical stress can also activate hidden TGF-β1, which further increases tissue stiffness. So, both mechanical stress and cellular responses work together to determine how stiff tissues become.
Now, I know this might be difficult to digest, to make it easier think of TGF- β1 as “cement”.
- Fibroblastsare like construction workers—they don’t just make collagen (the building blocks of tissues); they can also contract and shape the environment around cells.
- TGF-β1 (the cement)Helps fibroblasts change into myofibroblasts, which are specialised workers that produce more collagen. As they do this, tissues become stiffer.
- However, tissue stiffness isn’t only caused by the ‘cement’.Physical stress, or tension in the tissue contribute to the stiffness.
- Fibroblasts can sense physical stress, and they need a certain level of it to become myofibroblasts. Without this stress, they wouldn’t fully specialize or contract effectively.
- Mechanical stress can also activate hidden ‘cement’ (TGF-β1),further increasing stiffness by ramping up collagen production.
- In the end, both mechanical stress and the ‘cement’ work togetherto control how stiff tissues become—kind of like how both the cement and pressure in a building determine its final strength.
An early inflammatory response at the onset of Frozen Shoulder
Definitions:
- Connective tissue = “Connective tissues bind structures together, form a framework and support organs and the body as a whole. It helps to store fat, transport substances, protect against disease, and help repair tissue damage”
Traditionally, fibroblasts are known for their role in building and changing the ‘scaffolding’ of connective tissue. But they also act as watchful cells in the immune system, influencing the arrival and actions of immune cells.
Recent studies indicate that an early immune response with too many inflammatory signals might trigger frozen shoulder, setting off a series of tissue changes. These signals can affect how fibroblasts grow, work, and change, disrupting collagen-building.
What Triggers The Onset Of Adhesive Capsulitis?
The exact cause of frozen shoulder remains uncertain, similar to many diseases. While microtrauma has been proposed as a trigger, evidence is limited. Increasingly, a low-level, long-lasting inflammation is considered significant for frozen shoulder development.
This can be caused by a number of factors:
- Overuse, for example, frequent rotator cuff related shoulder pain type problems
- Autoimmune conditions such as rheumatoid arthritis, which attack bodies own cells causing inflammation.
- Metabolic conditions such as diabetes or thyroid disorders are associated with systemic inflammation.
- Infection
- Genetics, some people may just be more susceptible to chronic inflammation in the joints.
- Hormonal imbalances, particularly in women during hormonal fluctuations such as menopause, can influence inflammation
Markers of chronic inflammation are elevated in patients suffering from this condition.
Conditions like diabetes and thyroid disorders, linked to inflammation, have a higher frozen shoulder risk. Even personality traits and depression, linked to inflammation, may contribute. Female hormones can contribute as well, due to the higher incidence in perimenopausal women, but a direct link hasn’t been confirmed in current studies.
Why only the shoulder?
Throwing accurately and forcefully is a significant skill developed through human evolution, shaping the shoulder for energy storage and strong external rotation. In our modern sedentary lifestyle, the front of the shoulder capsule and ligaments might not get enough exercise or stretching due to reduced throwing and overhead actions.
This could make these structures more vulnerable to oxidative stress, linked to inflammation. Interestingly, manual labourers seem less prone to frozen shoulder, possibly due to more shoulder use.
Also, the less dominant side might be affected less. Although it’s not fully understood, the decline of myofibroblasts through apoptosis could explain the reversibility seen in frozen shoulder’s later stages, similar to how they vanish after wound healing.
The Pattern And Frequency Of Frozen Shoulder – Epidemiology
The exact epidemiology of frozen shoulder can vary based on factors such as:
- Age
- Gender
- Underlying health conditions.
De La Serna et al estimated that it affects around 2% to 5% of the general population. It most commonly occurs in individuals between the ages of 40 and 60, although it can occur at any age. Women are more commonly affected than men, with a reported female-to-male ratio of 2:1 to 3:1.
Symptoms & Clinical presentation
There are 3 main complaints you need to look out for to increase the suspicion of frozen shoulder:
- Frozen shoulder mainly affects the non-dominate hand, about 70% of the time
- Gradual onset of shoulder pain
- Gradual reduction in shoulder range of motion, especially external rotation and flexion
Clinical Course of Frozen shoulder
The condition tends to naturally resolve itself over time. Typically, this process takes around 18 to 24 months. However, it’s important to note that some people may experience ongoing symptoms and movement limitations that extend beyond 3 years.
Studies suggest that up to 40% of patients may fall into this category. Additionally, a smaller percentage, approximately 15% of patients, might unfortunately face permanent disability due to the condition.
The 3 phases Of Adhesive Capsulitis
Frozen shoulder usually follows three distinct phases:
Freezing Phase (Painful Phase):
- This initial phase, lasting approximately 2 to 9 months, is marked by significant pain.
Frozen Phase (Stiffness Phase):
- Following the painful phase, the frozen phase sets in, which typically spans 4 to 12 months. During this period, stiffness becomes a prominent issue.
Thawing Phase (Recovery Phase):
- Finally, the recovery phase takes place over 5 to 24 months, during which a gradual improvement in symptoms and mobility occurs.
However, it’s important to note that these phases might not be the most accurate way to describe the condition for two reasons:
Natural History Misconception: Using these phases may mistakenly lead patients to believe that they will inevitably progress through them and eventually recover fully without any treatment. This can be misleading and discourage timely intervention.
Variable Symptoms: Some patients have reported experiencing varying degrees of shoulder symptoms for longer periods, ranging from 2 to 7 or more years after initial symptoms appeared.
Imaging
Adhesive capsulitis is usually diagnosed based on clinical findings. It aligns with the slow emergence of shoulder pain and restricted range of motion, particularly in external rotation and forward flexion.
Currently, imaging isn’t typically needed to diagnose adhesive capsulitis. Instead, imaging is primarily used to rule out different sources of shoulder pain, like arthritis or issues with the rotator cuff or labrum.
Surgery
Surgical management of adhesive capsulitis is typically considered when conservative treatments have not provided significant relief or when the condition causes severe pain and functional limitations.
The surgical options include:
Arthroscopic Capsular Release:
Arthroscopic surgery is the most common surgical procedure used to treat frozen shoulder. It involves making small incisions and using a tiny camera (arthroscope) and surgical instruments to release the tight and contracted capsule around the shoulder joint. The surgeon cuts or releases the adhesions that are restricting shoulder movement. This procedure is less invasive than open surgery, which can help reduce recovery time.
Manipulation Under Anesthesia with Arthroscopic Capsular Release:
In some cases, manipulation under anesthesia (MUA) may be performed before or during arthroscopic capsular release. During MUA, the patient is put under anesthesia, and the surgeon manually moves the arm to break up adhesions and improve range of motion. This is often followed by arthroscopic capsular release to further release any remaining adhesions.
Open Capsular Release:
Open surgery involves making a larger incision to directly access the shoulder joint capsule and release the adhesions. While this approach provides better visualisation and access, it is more invasive and typically requires a longer recovery period compared to arthroscopic surgery.
Rotator Interval Closure:
In some cases, a procedure known as rotator interval closure may be performed during arthroscopic surgery. The rotator interval is a part of the capsule that is often involved in adhesive capsulitis. Closing the rotator interval can help stabilise the shoulder and prevent future adhesions.
Risk Factors For Developing Adhesive Capsulitis
- Female gender. It’s not fully known why, however, it is believed to be linked to hormonal changes and the fact that women having more lax ligaments, which makes them more susceptible to microtrauma and, thus chronic inflammation
- Diabetes mellitusis a significant risk factor for adhesive capsulitis. People with diabetes have a five times higher prevalence rate than general population.
- Other conditions like thyroid issues, rheumatological diseases, and certain medical factors like Parkinson’s, adrenal insufficiency, heart-lung problems, and previous traumaor surgery can also contribute to adhesive capsulitis, especially in secondary cases.
Assessment – Identifying Frozen Shoulder
Frozen shoulder is relatively simple to diagnose at later stages of the condition, however it can masquerade as all types of shoulder injury in the early stages. To raise your suspicions from a subjective point of view you want to listen out for:
- Gradual increase in pain
- Gradual loss of range of motion
- Dull ache throughout the day
And whilst it won’t help to diagnose, gather if the patient has
- Had a traumatic event (fracture, fall, dislocation)
- Arthritis
- Diabetes
- Thyroid issues
- Previous history of shoulder pain
This will help to piece the information together, and if enough flags are noticed, it will help lead the clinical management.
Objective assessment
To increase the suspicion of frozen shoulder even further, the following needs to be observed:
- Reduced passive range of motion of >50% in external rotation (compared to opposite arm)
- Reduced passive range of motion of >25% in flexion and abduction (compared to opposite arm)
Early management
Conservative methods
When managing adhesive capsulitis, conservative treatment remains the first line of action, particularly before any surgical intervention is considered. In the early stages, a combination of physiotherapy, nonsteroidal anti-inflammatory drugs (NSAIDs), and corticosteroid injections directly into the glenohumeral joint often has positive effects, especially when pain is a dominant complaint. Physiotherapy at this point focuses on pain relief and maintaining as much mobility as possible, using gentle mobilisations and exercises tailored to the individual’s tolerance.
However, it’s important to acknowledge the limitations of conservative care. While physiotherapy and NSAIDs are frequently used to address initial symptoms, current evidence doesn’t definitively support their standalone effectiveness in providing long-term benefits.
In cases where adhesive capsulitis progresses to more advanced stages, physiotherapy benefits may decrease, as the condition becomes less responsive to manual load.
This is where corticosteroid injections can help to manage inflammation and improve patient comfort, potentially facilitating better outcomes when combined with exercise.
- NSAIDs for Pain Relief: NSAIDs can provide short-term pain relief in early stages of the condition. They work by suppressing the activity of COX-1 and COX-2 enzymes, which are involved in synovitis-related inflammation
- Stretching Exercises for Collagen Remodelling: Controlled stretching exercises, up to a tolerable level of pain. The gentle tensile pressure can favour collagen remodelling, which is important for tissue healing. A study by Lubis and colleaguesfound that stretching exercises were superior to supervised neglect.
Effectiveness of Corticosteroid Injections:
Corticosteroid injections are used to manage frozen shoulder, particularly in the early stages of the condition. With strong evidence supporting its use, they target inflammation within the joint, suppressing cellular responses effectively while also preventing the transformation of fibroblasts into myofibroblasts, a process that contributes to tissue stiffness.
The timing of the injection is VITAL — when administered early (first month of symptom onset), corticosteroids can significantly reduce clinical symptoms, giving relief that physiotherapists can build upon with sensible loading and mobility.
It’s important to mention that while these injections decrease inflammation, they cannot reverse the fibrotic changes that occur as the condition progresses. This makes early intervention essential, as pushing the shoulder beyond its pain threshold in this phase could aggravate the inflammatory response and further activate fibroblasts, potentially exacerbating stiffness.
Other treatments to consider
- Hypertonic Saline Administration: Hypertonic saline, when administered, may be more effective than normal saline. Intra-Articular
- Hydraulic Distension: This technique involves injecting fluid into the joint to improve pain and function in the short term. Benefits are noticeable up to 3 months after the procedure. Diabetic patients might have less favourable outcomes compared to non-diabetic patients.
Exercise Based Management
Although evidence suggests that exercise may not significantly improve range of motion or slow the progression of frozen shoulder, it’s still beneficial for patients to engage in pain-free physiotherapy.
Doing so can enhance pain tolerance, build internal locus of control, and contribute to overall well-being.
For frozen shoulder we typically focus on two areas:
- Thoracic range of motion
- Rotator cuff activation
Depended on shoulder irritability during movements here are a few exercises that can be prescribed
High irritability
- Using stick for assistance – External rotation (2 sets-10/15 reps) | 1-2x a day
- Supine flexion with stick (2 sets -10/15 reps) | 1-2x a day
- Thoracic mobility | Rotation & extension (2 sets-10/15 reps) 1-2x a day
- Isometric Internal/external rotation (at door frame) and abduction (3 sets /30sec)
Moderate irritability
- Active external rotation (start at elbows to the side and move to 90 degrees as pain allows)
- Supine flexion with weighted stick (2 sets-10/15 reps) | 1-2x a day
- Thoracic mobility | Rotation & extension (2 sets-10/15 reps) | 1-2x a day (Rotation: hand wide and reaching as far as possible | Extension: Arms behind shoulder)
- Banded internal/ external rotation & lateral raise (90degrees) (3 sets – 10-15 reps) 2-3x a week
Low irritability
- Can do same us moderate irritability or progress further if appropriate (as pain allows)
- Weighted supine external rotation
- Weighted supine single arm pullover (4 sets – 10-15 reps) 2-3x a week
- Thoracic rotation (Follow hand with eyes through a full up and down rotation of hand)
Guidelines From NICE
The following is the summarised guidelines from NICE, for your convenience: Visit the website for a more comprehensive overview.
Diagnosis and Expectations
- Pain and stiffness are main symptoms.
- Pain is worse initially, especially at night.
- Pain improves gradually, but stiffness worsens and then resolves.
- The condition is self-limiting and can take months to years to resolve.
Activity Modification and Pain Control:
- Advise people to use their arm for movement but avoid positions of pain.
- Advise the use of analgesia when in early stages.
- Hot packs may offer some relief.
- Advise to set up pillows so that they support the arm in bed.
Management:
- Start with non-invasive treatments.
- Consider severity of symptoms and impact on daily life.
- Offer analgesia, especially in early phase.
- Consider paracetamol first, then NSAIDs or codeine.
- Consider physiotherapy: 6-week course, can be extended if improving.
- Physiotherapy includes education, exercises, manual therapy, etc.
- Intra-articular corticosteroid injection if no progress with conservative treatment. Injection can be done by appropriately trained person. Monitor for potential adverse effects, especially in diabetes.
Other Conditions You Should Be Aware Of
Condition | Symptoms |
Rotator Cuff Tears: | Similar to tendinopathy but may include more significant weakness, sudden pain if tear is traumatic, limited range of motion, clicking or popping sounds during movement. |
Rotator cuff related shoulder pain | Persistent deep shoulder pain, weakness when lifting or moving the arm, limited range of motion, discomfort at night, and cracking sensations. Usually discomfort gets worse with activity and overhead shoulder movements. |
Labral Tears (SLAP Tears): | Deep, dull shoulder pain, clicking or popping with movement, feeling of instability, pain with lifting or carrying objects |
Biceps Tendinopathy: | Frontal shoulder pain, worsens with overhead activities or lifting, pain radiating down the upper arm, tenderness in the front of the shoulder. |
AC Joint Sprain or Arthritis: | Localized pain and tenderness over the AC joint at the top of the shoulder, pain worsens when crossing arms or lifting objects. Glenohumeral (Shoulder) |
Arthritis | Gradual onset of shoulder pain and stiffness, limited range of motion, pain worsens with movement and weight-bearing |
Thoracic Outlet Syndrome: | Numbness or tingling in the arm or fingers, pain in the neck, shoulder, and arm, weakness in the hand, worsens with certain arm positions |
Nerve Entrapment (e.g., Suprascapular Nerve): | Deep ache or burning pain in the shoulder, weakness in specific movements, discomfort may radiate down the arm. Referred Pain (e.g., Cervical Radiculopathy): Symptoms: Neck pain with radiation into the shoulder, arm, or fingers, tingling or numbness along the arm or hand |
Fractures or Dislocations: | Sudden, severe pain after trauma, visible deformity, limited range of motion, possible swelling or bruising |
Sources
- De la Serna, D., Navarro-Ledesma, S., Alayón, F., López, E. and Pruimboom, L., 2021. A comprehensive view of frozen shoulder: a mystery syndrome. Frontiers in Medicine, 8, p.638.
- Fields, B.K., Skalski, M.R., Patel, D.B., White, E.A., Tomasian, A., Gross, J.S. and Matcuk, G.R., 2019. Adhesive capsulitis: review of imaging findings, pathophysiology, clinical presentation, and treatment options. Skeletal radiology, 48, pp.1171-1184.
- Hand, C., Clipsham, K., Rees, J.L. and Carr, A.J., 2008. Long-term outcome of frozen shoulder. Journal of shoulder and elbow surgery, 17(2), pp.231-236.
- Hand, C., Clipsham, K., Rees, J.L. and Carr, A.J., 2008. Long-term outcome of frozen shoulder. Journal of shoulder and elbow surgery, 17(2), pp.231-236
- Kraal, T., Lübbers, J., van den Bekerom, M.P.J., Alessie, J., van Kooyk, Y., Eygendaal, D. and Koorevaar, R.C.T., 2020. The puzzling pathophysiology of frozen shoulders–a scoping review. Journal of Experimental Orthopaedics, 7(1), pp.1-15.
- Kraal, T., Lübbers, J., van den Bekerom, M.P.J., Alessie, J., van Kooyk, Y., Eygendaal, D. and Koorevaar, R.C.T., 2020. The puzzling pathophysiology of frozen shoulders–a scoping review. Journal of Experimental Orthopaedics, 7(1), pp.1-15.
- Lubis, A.M.T. and Lubis, V.K., 2013. Matrix metalloproteinase, tissue inhibitor of metalloproteinase and transforming growth factor-beta 1 in frozen shoulder, and their changes as response to intensive stretching and supervised neglect exercise. Journal of Orthopaedic Science, 18, pp.519-527.
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