Scapulothoracic crepitus, more commonly known as snapping scapula syndrome, is a condition that causes a pronounced grating, popping or cracking in the shoulder that is both palpable and audible. Symptoms manifest most commonly when lifting the arm above the head or as a part of the throwing motion. This condition is often accompanied by pain.
The snapping phenomenon, known as crepitus, occurs when something interferes with the normal soft tissue (tendon, muscle or bursa) movement between the scapula (shoulder blade) and the rib cage. This condition has historically presented a diagnostic challenge, due to the shoulder’s complex anatomical structure. For this reason, it goes undiagnosed in many patients.
Causes of Snapping Scapula Syndrome
In normal arm movement, the scapula (shoulder blade) glides smoothly along the thoracic wall. When this movement is disrupted in some way, snapping scapula syndrome develops. A number of factors can be responsible for the development of this condition, including muscle abnormality, scapular bursitis and soft or bony tissue abnormality.
Inflammation from overuse, especially repetitive overhead motion, is the most common cause of this condition. Muscular atrophy, bone abnormality, abnormal bone formation and bone misalignment are also common causes of snapping scapula.
This condition is most commonly diagnosed in young, active patients; however, it can affect patients of any age. Those who play sports or work in a field requiring overhead motion, including baseball players, weight lifters, carpenters and wallpaper hangers, face an increased risk.
Symptoms and Diagnosis of Snapping Scapula Syndrome
The most common presenting symptoms of this disorder are pain associated with overhead arm movement and the accompanying snapping or grinding sounds and feelings that characterize this syndrome. Some patients experience only snapping or popping in the shoulder, without any associated pain.
Snapping scapula syndrome is often incorrectly diagnosed, due to its somewhat enigmatic origin. After taking a detailed medical history, the doctor will manipulate the arm to check alignment, assess pain and listen for any snapping or popping sounds.
The doctor will typically also order X-rays to detect potential bone abnormalities. If necessary, a CT scan, MRI or ultrasound image may be recommended to further evaluate bone and soft tissue.
Snapping Shoulder Syndrome Treatment
Fortunately, a non-surgical approach is effective for relieving this condition in many cases.
For most patients, the doctor will begin by recommending a conservative treatment approach. This includes resting the affected arm and modifying behaviors that may have contributed to the problem. Nonsteroidal anti-inflammatory drugs (NSAID) may be recommended, along with heat, ice and ultrasound therapy.
Once the symptoms have subsided, physical therapy and a prescribed exercise regimen can help to retrain and rebalance physical motion and strengthen key muscle groups.
If the problem persists, local corticosteroid injections may be recommended. If this fails to relieve the pain, or if the problem originates from a bone abnormality, surgical intervention may be necessary. Arthroscopic surgery is the preferred approach; however, open surgery may be necessary for some patients.
Post-surgical rehabilitation includes gradually increasing range of motion followed by strengthening and resistance. In most cases, patients can resume their sport or work-related activities three to four months after snapping scapula surgery.