Shoulder pain and restricted movement are common issues. While both shoulder impingement and frozen shoulder can cause discomfort and limit arm function, they represent distinct medical conditions with different origins and characteristics.
Understanding Shoulder Impingement
Shoulder impingement occurs when the rotator cuff tendons or the bursa become compressed within the subacromial space of the shoulder. This compression irritates and swells the tissues.
This condition often develops from repetitive overhead activities, common in athletes and individuals whose occupations involve frequent arm elevation. Other factors include bone spurs, joint inflammation, or poor posture. Symptoms involve pain when raising the arm, especially above shoulder height, and arm weakness. Pain may also worsen at night.
Understanding Frozen Shoulder
Frozen shoulder, or adhesive capsulitis, is characterized by progressive stiffness and pain in the shoulder joint. It occurs when the joint capsule, the connective tissue surrounding the shoulder, thickens and tightens. Inflammation, fibrosis, and scar tissue formation within the capsule contribute to this restriction.
The condition progresses through three stages. The “freezing” stage involves increasing pain and a gradual loss of motion, often worsening at night, and can last for several months. The “frozen” stage follows, where pain may subside, but the shoulder remains stiff, significantly limiting daily activities. Finally, the “thawing” stage marks a gradual return of motion and a decrease in pain. Factors increasing the likelihood of developing frozen shoulder include age, female sex, diabetes, thyroid conditions, and prolonged immobility following an injury or surgery.
Key Distinctions Between the Conditions
While both conditions affect shoulder function, their underlying pathologies differ. Shoulder impingement involves the mechanical compression of tendons and the bursa, which are soft tissues. In contrast, frozen shoulder arises from changes within the joint capsule itself, leading to its thickening and contraction. This fundamental difference in cause results in distinct symptom patterns.
Range of motion limitations also vary. Impingement restricts specific movements, particularly those involving overhead arm elevation or reaching behind the back. For frozen shoulder, the restriction is a generalized and progressive loss of both active and passive movement across all directions of the shoulder joint. This means someone cannot move their arm, nor can someone else move it for them, through the full range of motion.
Pain characteristics differ. Impingement presents with sharp pain that intensifies with specific movements. This pain can be localized and may radiate down the arm. Frozen shoulder causes a more diffuse, aching, and persistent pain that may be present even at rest and often disrupts sleep. The onset of impingement can be sudden due to injury or gradual from overuse, while frozen shoulder often develops spontaneously or after minor trauma or periods of immobility, typically with a gradual onset of stiffness.
Diagnosis and Management Approaches
Medical professionals diagnose shoulder conditions through physical examination, assessing the shoulder’s range of motion and identifying specific pain patterns. Imaging studies also assist. X-rays can reveal bone spurs for impingement, while MRI or ultrasound provide detailed views of soft tissues like tendons and bursae. For frozen shoulder, imaging often rules out other conditions, as the diagnosis is primarily clinical.
Management strategies are tailored to each condition. For shoulder impingement, initial approaches often include rest, anti-inflammatory medications, and physical therapy focused on strengthening the rotator cuff muscles and improving shoulder mechanics. Corticosteroid injections may be administered to reduce inflammation and pain. If conservative treatments are insufficient, surgical options like arthroscopic decompression, which involves removing bone or inflamed tissue to create more space, may be considered.
Frozen shoulder management centers on pain control and restoring motion. This involves pain relievers, corticosteroid injections, and physical therapy emphasizing stretching and regaining flexibility. If stiffness persists despite extensive physical therapy, procedures such as manipulation under anesthesia or arthroscopic capsular release, which involves cutting tight parts of the joint capsule, may be performed to improve range of motion. A medical diagnosis is important for both conditions to ensure an appropriate treatment plan.