Michael J. Huang and Peter J. Millett
DEFINITION
Several terms have been used to describe the elements of scapulothoracic bursitis and crepitus, such as snapping scapula, washboard syndrome, scapulothoracic syndrome, and rolling scapula.
The first description of scapulothoracic crepitus is credited to Boinet in 1867.1
By 1904, Mauclaire5 had described three subclasses—froissement, frottement, and craquement—depending on the loudness and character of the sound.
Milch6 and then Kuhn et al4 added to the understanding by differentiating sounds of soft tissues (frottement) from those arising from an osseous lesion (craquement or crepitus).
ANATOMY
Major bursae
Infraserratus bursa located between the serratus anterior muscle and the chest wall
Supraserratus bursa located between the subscapularis and the serratus anterior muscles
Minor bursae
Not consistently identified on cadaveric or clinical studies
Adventitial in nature; thought to arise secondary to abnormal biomechanics of the scapulothoracic joint
Superomedial angle of the scapula
Infraserratus
Supraserratus
Spine of scapula
Trapezoid
Inferior angle of scapula
Infraserratus
PATHOGENESIS
Scapulothoracic bursitis can be caused by atrophied or fibrotic muscle, anomalous muscle insertions, or elastofibroma (rare benign soft tissue tumor located on the chest wall).
Osteochondromas and malunited fractures of the ribs or scapula can also cause pathology in this articulation.
Infectious causes include tuberculosis or syphilis.
The tubercle of Luschka is a prominence at the superomedial aspect of the scapula that can be excessively hooked and can cause altered biomechanics.
Scoliosis or thoracic kyphosis can contribute to scapulothoracic crepitus.
Unrelated disorders include cervical radiculopathy, glenohumeral pathology, and periscapular strain.
NATURAL HISTORY
Scapulothoracic disorders are often associated with repetitive overhead activities or with a history of trauma.
Constant motion leads to inflammation and a cycle of chronic bursitis and scarring.
Mechanical impingement and pain with motion are a result of tough fibrotic tissue, furthering the inflammatory cycle.
PATIENT HISTORY AND PHYSICAL FINDINGS
Repetitive overhead activities or trauma
Palpable or audible crepitus over the involved area
Occasionally bilateral or positive family history
Localized tenderness over the inflamed area is most common.
Superomedial border is the most commonly affected area.
Inferior pole is also a common site of pathology.
Pseudowinging (nonneurologic etiology) may result from fullness over the involved area and compensation of scapular mechanics due to pain.
Crepitus alone, without pain, may be physiologic and not warrant treatment.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Tangential scapular views to identify bony anomalies
Computed tomography is controversial but can be helpful if osseous lesions are suspected and plain radiographs are normal.
Magnetic resonance imaging (MRI) is also controversial but can identify the size and location of bursal inflammation.
Injection of a corticosteroid and local anesthetic is helpful to confirm the diagnosis.
DIFFERENTIAL DIAGNOSIS
Atrophied, fibrotic muscle or anomalous muscle
Malunited rib or scapular fracture
Mass (eg, elastofibroma, osteochondroma)
Infection (ie, tuberculosis, syphilis)
Scoliosis or kyphosis
Cervical spine radiculopathy
Glenohumeral disease
NONOPERATIVE MANAGEMENT
Rest
Nonsteroidal anti-inflammatory
Activity modification
Physical therapy
Local modalities
Periscapular strengthening, emphasizing subscapularis and serratus anterior
Postural training
Figure 8 harness for kyphosis
Injection may be of benefit for both diagnosis and treatment.
SURGICAL MANAGEMENT
Indicated for patients who have failed to respond to conservative therapy
Open treatment
FIG 1 • The arm behind the back in extension and internal rotation: the “chicken wing” position.
Has been used successfully in treatment of both bursitis7,9 and crepitus6,8
Requires fairly large exposure and subperiosteal dissection of the medial musculature, with repair back to bone after débridement of pathologic tissue is accomplished
Arthroscopic treatmen.
Minimizes morbidity of the exposure and facilitates early rehabilitation and return to function
Preoperative Planning
If a bony mass is detected, computed tomography findings will help guide the planned resection.
Positioning
The patient is placed in the prone position, with the arm behind the back in extension and internal rotation (the socalled chicken wing position; FIG 1).
Approach
Decisions regarding open versus arthroscopic treatment for these disorders should be based on surgeon experience and comfort level.
POSTOPERATIVE CARE
Sling for comfort
Gentle passive motion immediately
Active and active-assisted motion and isometric exercises are started at 4 weeks postoperatively.
Periscapular strengthening starts at 8 weeks postoperatively.
OUTCOMES
No large series of arthroscopic treatment have been published.
Several smaller series have reported favorable outcomes after arthroscopic surgery.2,3
COMPLICATIONS
Pneumothorax
Infection
Inadequate resection, recurrence of symptoms
TECHNIQUES
ARTHROSCOPIC PORTALS
The initial “safe” portal is 2 cm medial to the medial scapular edge at the level of the scapular spine, between the chest wall and serratus anterior (TECH FIG 1A).
Avoids dorsal scapular nerve and artery
The space is distended with 150 mL saline via spinal needle and then the portal is created.
After insertion of a 4.0-mm 30-degree arthroscope into the first portal, a second “working” portal is established under direct visualization (TECH FIGS 1B and 1D).
It is placed about 4 cm inferior to the first portal.
A 6-mm cannula is inserted into this portal.
An additional superior portal can be placed as described by Chan et al1 (TECH FIG 1C).
Portals superior to the scapular spine place the dorsal scapular neurovascular structures, accessory spinal nerve, and transverse cervical artery at risk, however.
TECH FIG 1 • Placement of the first arthroscopic portal (A), the second “working” arthroscopic portal (B), and the optional superior portal (C). D. Arthroscopic view from the first portal.
RESECTION
A methodical approach to resection is needed because there are minimal anatomic landmarks.
Radiofrequency ablation and motorized shaving are used (TECH FIG 2A,B).
The surgeon proceeds medial to lateral and inferior to superior.
Spinal needles can be used to outline the medial border of the scapula (TECH FIG 2C,D).
Switching portals and the use of a 70-degree arthroscope may be necessary (TECH FIG 2E,F).
The superomedial angle of the scapula is identified by palpation through the skin.
Radiofrequency is used to detach the conjoined insertion of the rhomboids, levator scapulae, and supraspinatus from the bone.
A partial scapulectomy is performed using a motorized shaver and burr.
The arm should then be placed through a range of motion to assess the resection.
TECH FIG 2 • A,B. Resection and débridement of the scapula. C,D. The spinal needle is used as a guide to the medial border of the scapula. E,F. Final débridement.
REFERENCES
1. Chan BK, Chakrabarti AJ, Bell SN. An alternative portal for scapulothoracic arthroscopy. J Shoulder Elbow Surg 2002;11:235–238.
2. Ciullo J, Jones E. Subscapular bursitis: conservative and endoscopic treatment of “snapping scapula” or “washboard syndrome.” Orthop Trans 1993;16:740.
3. Harper GD, McIlroy S, Bayley JI, et al. Arthroscopic partial resection of the scapula for snapping scapula: a new technique. J Shoulder Elbow Surg 1999;8:53–57.
4. Kuhn JE, Plancher KD, Hawkins RJ. Symptomatic scapulothoracic crepitus and bursitis. J Am Acad Orthop Surg 1998;6:267–273.
5. Mauclaire M. Craquements sous-scapulaires pathologiques traits par l'interposition musculaire interscapulothoracique. Bull Mem Soc Chir Paris 1904;30:164–168.
6. Milch H. Partial scapulectomy for snapping of the scapula. J Bone Joint Surg Am 1950;32A:561–566.
7. Nicholson GP, Duckworth MA. Scapulothoracic bursectomy for snapping scapula syndrome. J Shoulder Elbow Surg 2002;11:80–85.
8. Richards RR, McKee MD. Treatment of painful scapulothoracic crepitus by resection of the superomedial angle of the scapula: a report of three cases. Clin Orthop Relat Res 1989;247:111–116.
9. Sisto DJ, Jobe FW. The operative treatment of scapulothoracic bursitis in professional pitchers. Am J Sports Med 1986;14:192–194.