Shoulder Capsulitis (Frozen Shoulder): Causes, Symptoms, Diagnosis, and Treatment

What is capsulitis in the shoulder?

Capsulitis in the shoulder refers to the inflammation, thickening, and contraction of the joint capsule surrounding the glenohumeral (shoulder) joint, leading to pain and a significant restriction in range of motion.

Understanding Shoulder Anatomy

To fully grasp capsulitis, it's essential to understand the basic anatomy of the shoulder joint. The shoulder is a ball-and-socket joint, formed by the head of the humerus (upper arm bone) fitting into the glenoid cavity of the scapula (shoulder blade). This joint, known as the glenohumeral joint, is the most mobile joint in the human body, allowing for a vast range of movements.

Encasing this joint is a fibrous sac called the joint capsule. This capsule, along with surrounding ligaments and muscles (including the rotator cuff), provides stability while allowing mobility. The inner lining of the capsule, the synovial membrane, produces synovial fluid, which lubricates the joint and nourishes the cartilage. In a healthy shoulder, the capsule is loose and pliable, allowing for full, uninhibited movement.

What Exactly is Capsulitis?

Capsulitis, specifically in the context of the shoulder, describes a condition where the normally loose and elastic joint capsule becomes inflamed, thickened, scarred, and contracts. This process effectively shrinks the space within the joint and restricts its movement, leading to characteristic pain and stiffness.

The most common and well-known form of shoulder capsulitis is adhesive capsulitis, often referred to as "frozen shoulder." While "capsulitis" can broadly refer to any inflammation of the capsule, "adhesive capsulitis" specifically denotes the progressive loss of both active (self-initiated) and passive (assisted) range of motion due to the adhesions and thickening within the capsule.

Types of Shoulder Capsulitis

Shoulder capsulitis is primarily categorized into two types based on its origin:

• Primary (Idiopathic) Adhesive Capsulitis: This is the most common form, where there is no clear identifiable cause for the onset of the condition. It develops spontaneously, often without any preceding injury or event.
• Secondary Adhesive Capsulitis: This type occurs as a result of an identifiable cause or underlying condition. It can be further subdivided:
  • Systemic: Associated with certain medical conditions like diabetes mellitus (the most common systemic link), thyroid disorders (hyper- or hypothyroidism), Parkinson's disease, and cardiac disease.
  • Extrinsic: Caused by conditions outside the shoulder joint but affecting its use, such as cervical radiculopathy, stroke, or humerus fractures requiring immobilization.
  • Intrinsic: Arising from conditions within the shoulder joint itself, such as rotator cuff tears, biceps tendinopathy, calcific tendinitis, or after shoulder surgery.

Causes and Risk Factors

While primary capsulitis has no definitive cause, several factors increase the risk of developing both types:

• Age and Gender: Most commonly affects individuals between 40 and 60 years old, with a higher prevalence in women.
• Diabetes Mellitus: This is the most significant risk factor, affecting up to 20% of diabetic patients. The exact link is unclear but may involve changes in collagen structure.
• Thyroid Disorders: Both hyperthyroidism and hypothyroidism are associated with an increased risk.
• Immobilization: Prolonged immobilization of the shoulder due to injury (e.g., fracture, dislocation), surgery, or stroke significantly increases the risk.
• Cardiac Conditions/Surgery: Patients with heart disease or those who have undergone open-heart surgery may be at higher risk.
• Parkinson's Disease: The neurological effects can lead to decreased arm swing and shoulder movement.
• Trauma or Surgery: Direct injury to the shoulder or surgical procedures on the shoulder or surrounding areas can trigger capsulitis.

Signs and Symptoms

Capsulitis typically progresses through distinct stages, each characterized by specific symptoms:

1. Freezing Stage (Painful Stage):

   • Gradual onset of pain: Initially a dull ache, which progressively worsens, often at night or with movement.
   • Increasing stiffness: The range of motion slowly begins to decrease, often unnoticed at first.
   • This stage can last from 2 to 9 months.

2. Frozen Stage (Stiffening Stage):

   • Significant stiffness: Pain may lessen or stabilize, but the shoulder becomes markedly stiff, with a severe loss of range of motion in all directions (especially external rotation, abduction, and internal rotation).
   • Difficulty with daily activities: Tasks like reaching overhead, dressing, or sleeping on the affected side become very challenging.
   • This stage can last from 4 to 12 months.

3. Thawing Stage (Resolution Stage):

   • Gradual return of motion: Pain continues to decrease, and the range of motion slowly but steadily improves.
   • This stage can be the longest, lasting from 5 months to 2 years, or even longer in some cases. While many individuals regain most of their motion, some may experience residual stiffness.

Diagnosis

Diagnosing shoulder capsulitis typically involves a combination of:

• Clinical Examination: A thorough physical assessment is key. The healthcare professional will test both active (patient moves arm) and passive (examiner moves arm) range of motion. A hallmark of adhesive capsulitis is a significant restriction in passive range of motion, particularly external rotation. They will also palpate for tenderness and assess muscle strength.
• Medical History: The doctor will inquire about the onset of symptoms, previous injuries, medical conditions (especially diabetes or thyroid issues), and medications.
• Imaging Studies:
  • X-rays: Primarily used to rule out other conditions that can cause shoulder pain and stiffness, such as arthritis, fractures, or tumors. They typically appear normal in capsulitis.
  • Magnetic Resonance Imaging (MRI): While not always necessary, an MRI can show thickening and inflammation of the joint capsule and rule out other soft tissue injuries like rotator cuff tears.
  • Arthrography: In some cases, a contrast dye is injected into the joint before an X-ray or MRI. This can reveal a reduced joint capsule volume, a characteristic finding in adhesive capsulitis.

Treatment Approaches

Treatment for shoulder capsulitis focuses on managing pain, preserving and restoring range of motion, and improving function. The approach often depends on the stage of the condition and its severity.

• Conservative Management:

  • Pain Management:
    • Non-steroidal anti-inflammatory drugs (NSAIDs): Over-the-counter or prescription medications to reduce pain and inflammation.
    • Corticosteroid Injections: Injections of corticosteroids directly into the shoulder joint can significantly reduce pain and inflammation, particularly in the freezing stage, providing a window for physical therapy.
  • Physical Therapy: This is a cornerstone of treatment. A skilled physical therapist will guide the patient through:
    • Gentle stretching exercises: To improve flexibility and gradually increase range of motion.
    • Joint mobilization techniques: Manual therapy to improve joint mechanics.
    • Strengthening exercises: Once some motion is regained, exercises to strengthen the shoulder and surrounding muscles.
    • Modalities: Heat or ice packs to manage pain and muscle spasms.
  • Home Exercise Program: Consistent daily exercises are crucial for recovery.

• Interventional Procedures (for persistent cases):

  • Hydrodilatation (Distension Arthrography): Involves injecting a large volume of sterile saline, sometimes with corticosteroids and anesthetic, into the joint capsule to stretch and break up adhesions.
  • Manipulation Under Anesthesia (MUA): Performed under general anesthesia, the surgeon manually moves the shoulder through its full range of motion to forcibly break up adhesions and scar tissue. This procedure carries risks, including fracture or dislocation.
  • Arthroscopic Capsular Release: A minimally invasive surgical procedure where small incisions are made, and an arthroscope (a tiny camera) is inserted. The surgeon uses small instruments to cut and release the tightened parts of the joint capsule. This is typically reserved for severe, unresponsive cases.

Rehabilitation and Recovery

Rehabilitation for shoulder capsulitis is often a long and challenging process requiring significant patience and commitment.

• Consistency is Key: Adherence to a prescribed physical therapy program and home exercises is paramount for regaining motion and function.
• Gradual Progression: Exercises should be performed gently and within pain tolerance. Pushing too hard can exacerbate pain and inflammation.
• Focus Areas:
  • Range of Motion: Initially, passive and active-assisted range of motion exercises.
  • Flexibility: Stretching to lengthen the shortened capsule and surrounding muscles.
  • Strengthening: Once motion improves, exercises to strengthen the rotator cuff and periscapular muscles to support the joint.
  • Functional Training: Integrating shoulder movements into daily activities.
• Education: Understanding the stages of capsulitis and the expected recovery timeline helps manage expectations and maintain motivation. Full recovery can take anywhere from 1 to 3 years, and some individuals may experience minor residual stiffness.

Prevention Strategies

While primary capsulitis cannot always be prevented, certain measures can reduce the risk, especially for secondary forms:

• Early Mobilization: After a shoulder injury or surgery, follow your healthcare provider's instructions for early, gentle range of motion exercises to prevent stiffness.
• Manage Underlying Conditions: Effectively manage systemic diseases like diabetes and thyroid disorders with your doctor.
• Regular Activity: Maintain general physical activity and gentle shoulder movements to keep the joint mobile and healthy.
• Ergonomics: Be mindful of posture and repetitive movements that might strain the shoulder.

When to Seek Medical Attention

It is important to consult a healthcare professional if you experience:

• Persistent shoulder pain that does not improve with rest or over-the-counter pain relievers.
• Progressive loss of shoulder motion, making it difficult to perform daily activities.
• Shoulder stiffness that worsens over time.
• Any sudden, severe shoulder pain following an injury.

Early diagnosis and intervention can often lead to better outcomes and a faster recovery from shoulder capsulitis.

Conclusion

Capsulitis of the shoulder, particularly adhesive capsulitis, is a challenging condition characterized by pain and significant loss of shoulder mobility due to inflammation and contraction of the joint capsule. While its exact cause often remains elusive, understanding its stages, risk factors, and the comprehensive nature of its treatment—combining pain management with dedicated physical therapy—is crucial for effective recovery. With patience and adherence to a structured rehabilitation plan, most individuals can achieve substantial improvement in pain and shoulder function.