Frozen Shoulder: Symptoms, Types, Causes and Treatment

Frozen shoulder, also known as adhesive capsulitis, is a challenging and often misunderstood condition that can significantly impact quality of life. Characterized by pain and progressive stiffness in the shoulder joint, it can interfere with daily activities, sleep, and overall well-being. Understanding the symptoms, types, causes, and evidence-based treatments is essential for individuals, caregivers, and healthcare professionals. This comprehensive article brings together the latest research and expert consensus to demystify frozen shoulder and guide those affected through the journey from diagnosis to recovery.

Symptoms of Frozen Shoulder

Frozen shoulder typically presents as a combination of pain and a gradual reduction in shoulder mobility. The progression and severity of symptoms can vary, making early recognition important for optimal management. Below, we summarize the key features and provide an in-depth look at what to expect.

Symptom	Nature/Description	Impact on Daily Life	Source(s)
Pain	Gradual onset, often severe	Disrupts sleep, activities, mood	1, 3, 4
Stiffness	Progressive loss of movement	Difficulty with dressing, grooming, etc.	1, 3, 4
Limited ROM	Affects active & passive movement	Restricts reaching, lifting, external rotation	3, 6
Functional Loss	Reduced use of affected arm	Decreased work, recreation, self-care	2, 3, 6

Table 1: Key Symptoms

Gradual Onset and Progression

Frozen shoulder often begins subtly, with people noticing increasing discomfort in and around the shoulder. The pain is typically worse at night and may disturb sleep. As the condition advances, movements such as reaching overhead, dressing, or even combing hair become more difficult. Unlike some other shoulder conditions, both active and passive movements are restricted — meaning the shoulder cannot be moved fully, even if someone else tries to help 1, 3, 6.

Distinct Stages

The classic progression of frozen shoulder is often described in three overlapping phases:

1. Freezing (Painful) Stage:

   • Increasing shoulder pain, especially at night
   • Gradual loss of motion
   • Can last from 6 weeks to 9 months

2. Frozen (Stiff) Stage:

   • Pain may diminish, but stiffness persists
   • Marked limitation in range of motion, especially external rotation
   • Daily activities are most affected in this stage
   • Usually lasts 4–12 months

3. Thawing (Recovery) Stage:

   • Slow improvement in mobility
   • Pain continues to resolve
   • Full recovery may take 1–3 years, but some may have residual stiffness 1, 4, 12

Impact Beyond the Shoulder

The pain and disability of frozen shoulder can have a broad impact, leading to sleep disturbance, mood changes, and even symptoms of anxiety and depression. Studies have shown that depression, in particular, can worsen the perceived disability and pain in frozen shoulder patients 2. This underscores the importance of addressing both physical and emotional well-being during management.

Types of Frozen Shoulder

Not all frozen shoulders are the same. Understanding the classification helps tailor treatment and set realistic expectations for recovery.

Type	Description	Common Causes/Associations	Source(s)
Primary	Idiopathic, no clear cause	Often spontaneous, age 50–70	5, 6, 7
Secondary	Due to known cause or condition	Trauma, surgery, immobilization, or systemic disease	5, 6, 7, 10
Intrinsic	Due to shoulder pathology	Rotator cuff disease, biceps tendinitis	5, 6
Extrinsic	Due to non-shoulder-related factors	Stroke, heart attack, cervical issues	5, 6, 10
Systemic	Due to systemic illness	Diabetes, thyroid disorders	5, 6, 7

Table 2: Types of Frozen Shoulder

Primary (Idiopathic) Frozen Shoulder

Primary frozen shoulder arises without any obvious injury or underlying condition. It is most common in people between 50 and 70 years of age and slightly more frequent in women 3, 5, 6. The cause remains unclear, but biochemical and inflammatory changes within the capsule of the shoulder joint are thought to play a central role 1, 8, 11.

Secondary Frozen Shoulder

Secondary frozen shoulder develops in response to a specific event or medical problem:

• Intrinsic: Caused by issues within the shoulder itself, such as rotator cuff tears, tendonitis, or arthritis 5, 6.
• Extrinsic: Triggered by factors outside the shoulder, including prolonged immobilization after stroke, trauma, surgery, or certain neurological or cardiac events 3, 6, 10.
• Systemic: Associated with broader health conditions like diabetes or thyroid disease. These patients may have a more protracted or resistant course 5, 6, 7.

Why Classification Matters

The distinction between primary and secondary frozen shoulder is crucial because:

• Treatment approaches may differ (e.g., addressing underlying causes in secondary forms)
• Prognosis can vary, especially in systemic cases such as diabetes, where recovery may be slower and less complete 5, 6, 12

Causes of Frozen Shoulder

Despite decades of research, the exact causes of primary frozen shoulder remain elusive. However, several factors have been identified that may contribute to its development and progression.

Cause	Mechanism/Description	Notable Associations/Findings	Source(s)
Idiopathic	Unknown; possibly immune-mediated	Most common, especially in middle-aged adults	1, 8, 11
Immobilization	Reduced movement after injury/surgery	Stroke, fractures, prolonged rest	3, 10
Systemic Disease	Diabetes, thyroid disorders	Higher risk & more severe presentation	5, 6, 10
Inflammation	Cytokine-mediated tissue changes	Fibroblast activation, cytokine upregulation	1, 8, 9, 11
Fibrosis	Excess collagen, capsular thickening	Leads to joint contracture and stiffness	1, 9, 11
Chondrogenesis	Cartilage-like changes in capsule	May play a role in pathogenesis	9, 10

Table 3: Causes and Mechanisms

Pathophysiology: What Happens Inside the Shoulder?

Research shows that the joint capsule and surrounding tissues undergo a process of inflammation and fibrosis (scarring), leading to thickening and tightening around the shoulder joint. The process involves:

• Activation and proliferation of fibroblasts (cells that produce collagen and scar tissue)
• Upregulation of inflammatory cytokines (e.g., IL-6, IL-8)
• Transformation of fibroblasts into myofibroblasts, which further contract and stiffen the capsule
• Reduced joint fluid and obliteration of normal fatty spaces within the joint 1, 8, 9, 11

Risk Factors

Several risk factors can predispose individuals to frozen shoulder:

• Age and Sex: Most common between ages 50-70; slightly higher in women 3
• Prolonged Immobilization: After surgery, injury, or stroke, the risk increases if the arm is not moved regularly 3, 10
• Systemic Illness: Diabetes and thyroid diseases are strongly associated; up to 20% of diabetics may be affected 5, 6, 10
• Other Factors: Heart disease, Parkinson’s disease, and certain infections (e.g., herpes zoster affecting the shoulder) 3, 10

The Role of Inflammation and Fibrosis

Modern research has highlighted the interplay of immune mechanisms, inflammation, and tissue scarring:

• Fibroblast Activation: Abnormal activation leads to excess production of collagen and tissue contraction 1, 11
• Cytokine Dysregulation: High levels of pro-inflammatory mediators contribute to pain and tissue changes 1, 8, 11
• Chondrogenesis: Recent findings suggest cartilage-like changes in the joint capsule may also play a role 9, 10

Treatment of Frozen Shoulder

Frozen shoulder is often self-limiting, but its long course and disabling symptoms prompt many to seek treatment. A variety of approaches are used, from conservative measures to surgical intervention, tailored to the stage and severity of the disease.

Treatment	Description/Approach	Effectiveness/Considerations	Source(s)
Education	Patient information & reassurance	Essential for expectation management	7, 12
Physiotherapy	Stretching, mobilization, exercises	Improves motion/function, cornerstone	6, 12, 15
NSAIDs	Pain relief (oral medications)	Reduces pain, especially in early phase	7, 12
Steroid Injections	Intra-articular or subacromial	Short-term pain/mobility improvement	6, 12, 15, 16
Hydrodilatation	Joint capsule distension with fluid	Faster symptom relief, similar long-term outcomes	16
Manipulation under Anesthesia (MUA)	Shoulder forcibly moved under anesthesia	Similar effectiveness as physiotherapy, most cost-effective	15
Arthroscopic Capsular Release	Surgical cutting of capsule	For resistant cases; higher risks	13, 14, 15

Table 4: Treatment Options

Non-Operative Management

Patient Education and Expectation Setting

Educating patients about the natural history of frozen shoulder — that it usually resolves over time, though sometimes incompletely — is vital. Setting realistic expectations can reduce anxiety and improve adherence to therapy 7, 12.

Physiotherapy

• Stretching and Mobilization: Gentle, progressive exercises help maintain and recover range of motion.
• Manual Therapy: Skilled therapists may use joint mobilization techniques tailored to the patient’s pain level and stage of disease.
• Frequency: Structured programs (e.g., 12 sessions over 12 weeks) have been shown to be as effective as surgery in many cases 6, 15.

Medications

• NSAIDs: Useful for pain control, especially in the freezing phase 7, 12.
• Steroid Injections: Intra-articular steroids can provide rapid pain relief and improved motion, particularly when combined with physiotherapy, though benefits may be short-term 6, 12, 16.

Hydrodilatation

This procedure involves injecting a large volume of fluid (often with steroids) into the joint to stretch the capsule. It can provide faster symptom relief than other injections, but long-term outcomes are similar 16.

Surgical and Interventional Methods

Surgery is reserved for severe or persistent cases not responding to conservative therapy:

• Manipulation Under Anesthesia (MUA): The shoulder is gently manipulated while the patient is under anesthesia to break adhesions. Recent trials show it is cost-effective and as effective as arthroscopic surgery or physiotherapy at one year, though risks such as fracture or soft tissue injury exist 15.
• Arthroscopic Capsular Release: The tight capsule is surgically cut using minimally invasive techniques. This is effective for resistant cases but carries higher risks and costs compared to other methods 13, 14, 15.

Emerging and Adjunct Approaches

• Hydrodilatation and other injection therapies are being refined to optimize results.
• Patient-tailored rehabilitation based on pain/irritability levels is recommended, with progression of exercise intensity as symptoms improve 6.
• Psychosocial support: Recognizing and addressing depression or anxiety can improve overall outcomes 2.

What If Symptoms Persist?

A minority of patients (around 10%) do not respond to conservative measures. In these cases, more invasive interventions may be considered. However, even with surgery, some residual stiffness may remain 7, 12, 15.

Conclusion

Frozen shoulder is a complex, often frustrating condition, but understanding its symptoms, types, causes, and treatments can empower patients and clinicians alike. While the journey to recovery can be long, most individuals regain significant function with appropriate management.

Key Points:

• Frozen shoulder manifests as pain and progressive stiffness, with distinct stages and significant impact on daily life.
• It is classified as primary (idiopathic) or secondary (due to underlying causes), with further subclassification based on origin.
• The pathophysiology involves inflammation, fibrosis, and sometimes chondrogenesis in the joint capsule.
• Risk factors include age, sex, immobilization, diabetes, and thyroid disease.
• Treatment is individualized, starting with education, physiotherapy, and pain control; steroid injections, hydrodilatation, and—rarely—surgery are options for resistant cases.
• Most patients recover well with conservative care, though the process may take months to years.

By staying informed and working collaboratively with healthcare professionals, those affected by frozen shoulder can navigate the challenges and work towards regaining comfort and mobility.