Popping Shoulder: Causes, Diagnosis and When to Worry

To learn more, consult the guide on Shoulder Anatomy: Bones, Muscles, and Biomechanics. To learn more, consult the guide on Supraspinatus Tendinitis: Exercises and Recovery Times. To learn more, consult the guide on Shoulder Dislocation.

The shoulder is one of the most complex and mobile joints in the human body, essential for a wide range of daily and sports activities. It is not uncommon to feel or hear a sound during movement, a “click”, a “pop” or a “grinding”, commonly described as a cracking shoulder. This phenomenon, known in medical terms as crepitus, can cause concern, but in most cases, it is benign and not indicative of a serious pathology. However, in some circumstances, cracking can be a warning sign for underlying conditions that require medical and physiotherapy attention.

This article aims to thoroughly explore the causes of a cracking shoulder, distinguishing between harmless physiological mechanisms and pathological ones. It will analyze the associated symptoms that should prompt consultation with a professional, the diagnostic pathway, and physiotherapy treatment strategies, including specific exercises and prevention tips. The goal is to provide a comprehensive, evidence-based guide to better understand and appropriately manage this common symptom.

Table of Contents

• Functional Anatomy of the Shoulder: An Essential Overview
• The Cracking Phenomenon: Physiological and Pathological Mechanisms
• Common Causes of a Cracking Shoulder
• When to Worry: Warning Signs
• Diagnosis: The Clinical Pathway
• Physiotherapy Treatment: A Personalized Approach
• Prevention of Pathological Cracking Shoulder
• Frequently Asked Questions (FAQ)
• Conclusion
• Frequently Asked Questions
• Resources
• Sources and Scientific References

Functional Anatomy of the Shoulder: An Essential Overview

Functional anatomy of the shoulder is the study of how the complex joint structures in the upper arm and chest work together to enable movement and stability. To understand the phenomenon of cracking, it is essential to have a clear view of the shoulder’s anatomy. This region is an articular complex composed of several joints that work in synergy to ensure exceptional freedom of movement:

For a complete overview, see the comprehensive guide to shoulder pain.

• Glenohumeral Joint: It is the main joint, formed by the head of the humerus (the arm bone) and the glenoid fossa of the scapula (a shallow cavity). It is one of the most mobile joints in the body, but also one of the least stable, due to its conformation.
• Acromioclavicular Joint: Connects the clavicle (collarbone) with the acromion (a bony prominence of the scapula).
• Sternoclavicular Joint: Connects the clavicle to the sternum (breastbone).
• Scapulothoracic Joint: It is not a true anatomical joint, but rather a gliding plane between the scapula and the rib cage, fundamental for coordinated shoulder movement.

Around these bony structures, an intricate system of soft tissues ensures stability and movement:

• Articular Capsule and Ligaments: Surround the glenohumeral joint, providing passive stability and limiting excessive mobility.
• Glenoid Labrum: A ring of fibrous cartilage that surrounds the glenoid, deepening it and increasing the contact surface with the humeral head, improving stability.
• Rotator Cuff: A group of four muscles (supraspinatus, infraspinatus, teres minor, subscapularis) and their tendons that wrap around the head of the humerus. They are crucial for arm rotation and elevation, as well as dynamically stabilizing the glenohumeral joint.
• Bursae: Small sacs filled with synovial fluid that reduce friction between tendons, muscles, and bones, facilitating gliding. The subacromial bursa is the largest and most clinically relevant.
• Scapular Muscles: Muscles such as the trapezius, rhomboid, serratus anterior, and levator scapulae, which control the movement and position of the scapula, directly influencing shoulder function.

The complex interaction of these structures allows the shoulder to perform wide and powerful movements, but also makes it susceptible to a variety of problems that can manifest, among other symptoms, with cracking.

The Cracking Phenomenon: Physiological and Pathological Mechanisms

The sound heard when the shoulder cracks can result from various mechanisms, some of which are completely normal and harmless, while others indicate a pathological condition.

Physiological Mechanisms (Benign)

• Joint Cavitation: This is the most common and harmless mechanism of joint cracking, not only in the shoulder but also in other joints (e.g., fingers). Within the synovial fluid that lubricates the joints, gases (mainly nitrogen) are dissolved. When the joint is stretched or moved rapidly, negative pressure is created, leading to the formation of gas bubbles. The subsequent collapse of these bubbles produces a dry sound, a “pop” or “click”. This phenomenon is usually painless and not associated with joint damage.
• Physiological Movement of Soft Tissues: Tendons or ligaments can glide over bony prominences or other soft structures during movement. If this gliding occurs smoothly and without excessive friction, it can produce an audible sound or a “snapping” sensation without pain or inflammation. It is similar to the sound one might hear when tightening a string.

Pathological Mechanisms (Clinically Relevant)

When cracking is accompanied by pain, limited movement, weakness, or instability, it is likely indicative of a pathological condition. Mechanisms include:

• Friction between Articular Surfaces:

• Cartilage Degeneration (Osteoarthritis): The wear and tear of articular cartilage, which normally covers the bone ends and allows smooth gliding, can lead to direct contact between bone surfaces. This generates a “grinding” or “crepitating” sound (crepitus) during movement, often accompanied by pain and stiffness.

• Glenoid Labrum Lesions: Damage to the glenoid labrum can alter joint congruity and cause friction or tissue impingement, producing a click or painful locking.
• Abnormal Movement or Soft Tissue Impingement:

• Tendinopathies and Impingement: Inflammation or degeneration of tendons (e.g., rotator cuff or biceps) can cause them to glide abnormally or become compressed (impingement syndrome) under the acromion or other bony structures, generating a painful crack.

• Bursitis: Inflammation of the bursa can thicken it and alter its gliding function, causing friction and crepitus.
• Joint Instability:

• Capsuloligamentous Laxity: Excessively lax joint capsule and ligaments can allow the humeral head to move excessively within the glenoid, leading to subluxations (shoulder partially “coming out”) or complete dislocations. These abnormal movements are often accompanied by an audible “clunk” or “pop” and a feeling of instability.

• Intra-Articular Loose Bodies: Small fragments of cartilage or bone, detached due to trauma or degeneration, can move freely within the joint and become trapped between surfaces, causing clicks, locking, and pain.
• Scapulothoracic Dysfunction (Winged Scapula): Altered coordination or weakness of the muscles controlling the scapula can lead to abnormal movement of the scapula itself on the rib cage. This can generate an audible or palpable crack or “clunk” under the scapula, often accompanied by pain and dysfunction.

Distinguishing between these mechanisms is crucial for accurate diagnosis and effective treatment.

Common Causes of a Cracking Shoulder

Let’s now delve into the specific conditions that can manifest with a cracking shoulder, dividing them into benign and pathological causes.

Benign and Physiological Causes

• Joint Cavitation: As already mentioned, it is the most frequent cause. The crack is usually single, not immediately repetitive, and not associated with pain, swelling, or functional limitation. It does not require treatment.
• Physiological Movement of Soft Tissues: Tendons (e.g., biceps or rotator cuff) or ligaments can glide over bony prominences (e.g., greater tubercle of the humerus, coracoid process) during movement. If this occurs without irritation or inflammation, the sound is harmless.

Pathological and Clinically Relevant Causes

When cracking is accompanied by pain, weakness, limited movement, or a feeling of instability, one of the following conditions needs to be investigated:

• Impingement Syndrome (Subacromial Impingement): Occurs when the rotator cuff tendons (often the supraspinatus) or the subacromial bursa are compressed between the humeral head and the acromion during arm elevation movements. Cracking can be a symptom, often accompanied by acute or dull pain, especially during arm elevation or rotation.
• Rotator Cuff Tendinopathies: Inflammation (tendinitis) or degeneration (tendinosis) of the rotator cuff tendons can alter their gliding, causing painful cracking, weakness, and pain that worsens with movement or at night. Partial or complete tendon tears can also cause crepitus and significant weakness.
• Shoulder Instability: Can be caused by congenital ligamentous laxity, trauma (e.g., previous dislocations), or capsular lesions. The shoulder may crack or “click” when the humeral head moves excessively within the glenoid, giving a sensation of the “shoulder coming out” or apprehension.
• Osteoarthritis of the Glenohumeral or Acromioclavicular Joint: Progressive wear of the articular cartilage leads to bone-on-bone contact. This generates a “grinding” or “sandy” crepitus, accompanied by pain, stiffness, especially in the morning or after periods of inactivity, and limited movement.
• Glenoid Labrum Lesions (SLAP lesion, Bankart lesion): The glenoid labrum can suffer lesions due to trauma (e.g., falls on an outstretched arm, dislocations) or repetitive movements (e.g., overhead athletes). These lesions can cause a deep, painful click, a sensation of locking, pain inside the joint, and weakness.
• Subacromial Bursitis: Inflammation of the subacromial bursa, often associated with impingement or overuse, can cause pain and, occasionally, cracking or friction during movement.
• Winged Scapula (Scapulothoracic Dysfunction): Altered scapular kinematics, due to weakness or imbalance of the scapular muscles (e.g., serratus anterior, rhomboids), can cause the medial border of the scapula to lift off the rib cage during movement. This can produce an audible or palpable “clunking” or “popping” sound under the scapula, often associated with pain and fatigue.
• Intra-Articular Loose Bodies: Fragments of cartilage or bone, sometimes called “joint mice,” can break off and move freely within the joint. They can become trapped between articular surfaces, causing clicks, sudden locking of movement, and acute pain.
• Adhesive Capsulitis (Frozen Shoulder) in the initial phase: In the early stages of this condition, characterized by inflammation and progressive stiffness of the joint capsule, cracking or clicking may be felt before movement becomes severely limited.

When to Worry: Warning Signs

While most cracking is harmless, it is crucial to recognize the signs that indicate the need for a professional evaluation. You should consult a doctor or physical therapist if shoulder cracking is accompanied by one or more of the following symptoms:

• Persistent or increasing pain: Cracking that is consistently painful or whose pain worsens over time is the most important warning sign.
• Limited movement: Difficulty performing daily movements such as raising the arm, getting dressed, reaching for objects overhead or behind the back.
• Muscle weakness: Difficulty lifting or holding objects, or a sensation of loss of strength in the arm.
• Feeling of instability or “shoulder coming out”: A feeling that the shoulder is “loose” or might dislocate, especially during certain movements.
• Localized swelling or warmth: Signs of acute inflammation.
• Cracking that changes nature: If the sound becomes more frequent, louder, or if the associated sensation changes (e.g., from a click to a grind).
• Recent trauma: If the cracking started after a fall, a direct blow to the shoulder, or a sudden movement.
• Neurological symptoms: Numbness, tingling, or weakness radiating down the arm or hand, which could indicate nerve compression.

Ignoring these signs can lead to a worsening of the condition and a longer, more complex recovery.

Diagnosis: The Clinical Pathway

The diagnosis of a pathological cracking shoulder requires a systematic approach, starting with a thorough clinical evaluation and potentially including instrumental investigations.

Anamnesis and Physical Examination

• Detailed Anamnesis: The doctor or physical therapist will gather information about the symptom’s history:

• When did the cracking start?

• Is it associated with trauma?

• Which movements provoke it?

• Is it painful? How much?

• Are there other symptoms (weakness, instability, limitation)?

• What are the patient’s work or sports activities?

• Are there previous shoulder problems?
• Physical Examination: A complete evaluation of the shoulder and the cervical and thoracic regions will be performed:

• Inspection: Assessment of posture, symmetry, presence of swelling or muscle atrophy.

• Palpation: Identification of painful areas, muscle spasms, or bony abnormalities.

• Assessment of Range of Motion (ROM): Measurement of active and passive shoulder movements in all directions, looking for limitations or pain.

• Assessment of Muscle Strength: Specific tests for rotator cuff muscles, deltoid, and scapular muscles.

• Specific Tests: A series of clinical maneuvers (e.g., impingement tests, instability tests, glenoid labrum lesion tests) that help identify the involved structure and the nature of the problem.

• Assessment of Scapular Dynamics: Observation of scapular movement during arm elevation to identify dyskinesia.

Instrumental Investigations

Depending on the results of the physical examination, the doctor may request diagnostic tests to confirm the diagnosis or rule out other pathologies:

• X-ray (RX): Useful for visualizing bone structures, identifying signs of osteoarthritis (joint space narrowing, osteophytes), fractures, tendon calcifications, or bony loose bodies.
• Ultrasound: A dynamic examination that allows visualization of soft tissues (rotator cuff tendons, biceps tendon, bursae) in motion. It is effective for identifying tendinopathies, partial or complete tendon tears, bursitis, and joint effusions.
• Magnetic Resonance Imaging (MRI): Considered the “gold standard” for soft tissue evaluation. It provides detailed images of tendons, ligaments, capsule, glenoid labrum, and cartilage. It is essential for diagnosing rotator cuff tears, labral tears, adhesive capsulitis, and other complex pathologies.
• Computed Tomography (CT): Less common for a cracking shoulder, but can be useful for a detailed evaluation of bone structures in cases of complex fractures or for surgical planning.
• Diagnostic Arthroscopy: In rare cases, when other examinations are inconclusive and symptoms persist, arthroscopy may be performed for direct visualization of intra-articular structures. This procedure is usually combined with potential surgical treatment.

Physiotherapy Treatment: A Personalized Approach

Physiotherapy treatment for a pathological cracking shoulder is personalized based on the underlying cause, symptom severity, and patient goals. The approach is conservative in most cases and aims to reduce pain, restore mobility, improve strength and stability, and prevent recurrence.

Goals of Physiotherapy Treatment

• Pain and Inflammation Reduction: Manage acute symptoms to allow active participation in rehabilitation.
• Restoration of Range of Motion (ROM): Recover full joint mobility and soft tissue flexibility.
• Improvement of Strength and Endurance: Strengthen rotator cuff, scapular, and core muscles.
• Joint Stabilization: Improve motor control and proprioception to prevent instability.
• Postural and Movement Re-education: Correct dysfunctional movement patterns and incorrect postures.
• Patient Education: Provide the patient with tools to manage their condition and prevent future problems.

Phases of Treatment

1. Acute Phase (Pain and Inflammation Management)

If the cracking is painful and associated with inflammation:

• Relative Rest: Avoid movements that aggravate pain, but maintain light activity to prevent stiffness.
• Instrumental Physical Therapies:

• Cryotherapy (Ice): To reduce pain and swelling.

• TENS (Transcutaneous Electrical Nerve Stimulation): For pain modulation.

• Ultrasound, Laser Therapy, Tecar Therapy: Can be used to promote tissue healing and reduce inflammation.
• Passive and Assisted Mobilization: Gentle movements performed by the physical therapist or with patient assistance to maintain ROM without stressing the joint.

2. Subacute and Recovery Phase (Restoration of Function)

Once acute pain is under control, the focus shifts to functional recovery:

• Manual Therapy:

• Joint Mobilizations: Specific techniques to improve the mobility of the glenohumeral, acromioclavicular, and sternoclavicular joints.

• Soft Tissue Techniques: Massage, myofascial release, stretching to reduce muscle tension and improve capsule and ligament elasticity.
• Progressive Therapeutic Exercises:

• Mobility and Flexibility Exercises: Capsular stretching, stretching of pectoral, latissimus dorsi, and rotator cuff muscles to improve ROM and reduce stiffness.

• Rotator Cuff Strengthening: Specific exercises for the supraspinatus, infraspinatus, teres minor, and subscapularis muscles, using resistance bands, light weights, or body weight (e.g., internal and external rotations, abduction).

• Scapular Muscle Strengthening: Exercises to improve scapular stability and control (e.g., rowing, push-up plus, Y-T-W-L exercises).

• Core Strengthening: A stable trunk is fundamental for a healthy shoulder. Exercises for abdominals, lower back, and obliques.

• Motor Control and Proprioception Exercises: Exercises that improve awareness of shoulder position and movement in space, essential for dynamic stability (e.g., medicine ball exercises, exercises on unstable surfaces).
• Postural Re-education: Awareness and correction of incorrect postures that can contribute to shoulder problems.

3. Return to Activity and Prevention Phase (Maintenance and Prevention)

This phase aims to prepare the patient for a return to daily, work, or sports activities, and to prevent future recurrences:

• Functional and Specific Exercises: Exercises that simulate the movements required by the patient’s specific activities (e.g., throwing for athletes, overhead movements for certain professions).
• Home Maintenance Program: The physical therapist will provide a home exercise program to continue maintaining the achieved results and prevent the return of symptoms.
• Ergonomic Education: Advice on workplace ergonomics, correct lifting techniques, and activity modifications to reduce stress on the shoulder.
• Prevention Strategies: Information on proper warm-up and cool-down, the importance of gradually increasing training loads, and listening to one’s body signals.

Examples of Exercises (General, to be Adapted)

It is fundamental to emphasize that these are just examples and must be performed under the guidance of a physical therapist, who will adapt the program to the patient’s specific needs.

• Pendulum Exercises (Codman’s Pendulum): Lean forward, letting the arm hang. Perform small circles or swings back and forth, relaxing the shoulder. Useful for gentle mobilization in the acute phase.
• External Rotations with Resistance Band: Hold a resistance band with both hands, elbows at 90 degrees and close to the body. Rotate hands outwards, away from the body, against the resistance of the band. To strengthen external rotators.
• Scapular Squeezes: Sitting or standing, squeeze the shoulder blades together, as if trying to hold a pencil between them. Hold for 5 seconds and release. To activate the scapular retractors.
• Wall Slides: Standing facing a wall, place forearms and hands on the wall, with elbows bent at 90 degrees. Slowly slide arms upwards along the wall, keeping elbows close to the body, then slide back down. To improve mobility and scapular control.
• Pectoral Stretch: Standing in a corner of a room or in a doorway, place forearms on the walls with elbows at shoulder height. Slowly lean forward until a stretch is felt in the front of the shoulder and chest. Hold for 30 seconds. To improve posture and reduce anterior tension.

Prevention of Pathological Cracking Shoulder

Prevention plays a crucial role in maintaining shoulder health and reducing the risk of developing pathological conditions that cause painful cracking.

• Maintain Good Posture: Avoid curved postures or shoulders rolled forward, which can alter shoulder mechanics and increase the risk of impingement. An upright and aligned posture is fundamental.
• Balanced Muscle Strengthening: Develop balanced strength among all muscle groups of the shoulder, scapula, and trunk. Do not focus only on “visible” muscles (e.g., deltoids, pectorals), but also on the rotator cuff and scapular muscles.
• Flexibility and Mobility: Regularly perform stretching exercises to maintain the flexibility of the joint capsule and surrounding muscles.
• Adequate Warm-up: Before any physical or sports activity, dedicate time to a specific shoulder warm-up, including dynamic and light movements.
• Correct Techniques: Learn and apply correct techniques for lifting weights, performing repetitive movements, or playing sports. A physical therapist can provide valuable guidance.
• Avoid Overload and Gradual Progression: Avoid increasing training intensity, duration, or volume too quickly. The body needs time to adapt to new loads.
• Listen to Your Body: Do not ignore pain, discomfort, or cracking that changes nature. These are signals that require attention.
• Work Ergonomics: Adapt your workstation to support good posture and reduce stress on the shoulder, especially for those who perform sedentary jobs or repetitive movements.

Frequently Asked Questions (FAQ)

Conclusion

A cracking shoulder is a common symptom that, although often benign, should not be ignored, especially if accompanied by pain, weakness, or functional limitation. Understanding the anatomy of the shoulder and the different mechanisms that can generate this sound is the first step towards effective management.

An accurate diagnosis, based on a detailed anamnesis, a thorough physical examination, and, if necessary, instrumental investigations, is fundamental for identifying the underlying cause. Physiotherapy treatment, personalized and progressive, aims to restore function, reduce pain, and prevent recurrences through manual therapy, therapeutic exercises, and postural re-education.

In any case, in the presence of a persistent or symptomatic cracking shoulder, it is always advisable to consult a doctor or physical therapist. These professionals will guide the patient through the most appropriate diagnostic and therapeutic pathway, ensuring the best possible recovery and long-term shoulder health.

Frequently Asked Questions

What are the primary physiological mechanisms behind non-painful shoulder popping?

Non-painful shoulder popping often results from joint cavitation, where gas bubbles within the synovial fluid collapse due to pressure changes during movement. This phenomenon is generally benign and does not indicate joint damage. Other physiological causes include the snapping of tendons or ligaments over bony prominences as the joint moves.

Which pathological conditions are commonly associated with painful shoulder popping?

Painful shoulder popping can be indicative of underlying pathological conditions affecting the joint structures. These may include tendinopathies, labral tears, glenohumeral instability, or early-stage osteoarthritis. Such conditions often involve mechanical irritation or damage to the soft tissues or cartilage within the shoulder.

When is it advisable to seek professional medical evaluation for shoulder popping?

Professional medical evaluation is recommended when shoulder popping is accompanied by pain, weakness, instability, or a significant reduction in the range of motion. These symptoms suggest a potential underlying issue that may require diagnosis and intervention. A thorough assessment can help determine the cause and guide appropriate management.

How does a physical therapist typically approach the treatment of pathological shoulder popping?

A physical therapist typically begins with a comprehensive assessment to identify the specific cause and contributing factors of pathological shoulder popping. Treatment then involves a personalized exercise program designed to improve shoulder strength, mobility, and stability. This approach aims to restore optimal joint mechanics and reduce symptoms.

For a broader overview of related conditions, see our shoulder pain guide.

Sources and Scientific References

1. Kawchuk GN, Fryer J, Jaremko JL, et al. Real-time visualization of joint cavitation. PLoS One. 2015;10(4):e0119470. DOI: 10.1371/journal.pone.0119470
2. Protopapas M, Cymet TC. Joint cracking and popping: understanding noises that accompany articular release. J Am Osteopath Assoc. 2002;102(5):283-287.
3. Castellanos J, Axelrod D. Effect of habitual knuckle cracking on hand function. Ann Rheum Dis. 1990;49(5):308-309. DOI: 10.1136/ard.49.5.308