Shoulder Impingement Syndrome

By admin Last updated Mar 3, 2024

Ovid: 5-Minute Orthopaedic Consult

Editors: Frassica, Frank J.; Sponseller, Paul D.; Wilckens, John H.

Title: 5-Minute Orthopaedic Consult, 2nd Edition

> Table of Contents > Shoulder Impingement Syndrome

Shoulder Impingement Syndrome

Kevin W. Farmer MD

John H. Wilckens MD

James F. Wenz Sr MD

Basics

Description

Shoulder pain with overhead activities is a common musculoskeletal complaint.
Impingement syndrome:
- Inflammatory condition of the soft tissues of the subacromial space
- Most common cause of presentation for shoulder complaints to a physician’s office (>50% of all shoulder complaints) (1)
Represents a continuum, progressing from
acute bursitis, to chronic bursitis, to partial-thickness tears of the
rotator cuff, to full-thickness rotator cuff tears, to rotator cuff
arthropathy with degenerative changes
The subacromial space is defined as the
humeral head inferiorly, the anterior edge and undersurface of the
anterior 1/3 of the acromion, and the coracoacromial ligament and AC
joint superiorly.
The soft tissues of the subacromial space
include the subacromial bursa, supraspinatus and infraspinatus tendons,
tendon of the long head of the biceps, and capsule of shoulder, all of
which are susceptible to inflammation.
External impingement:
- The most common type of impingement
- With overhead elevation of the arm, the rotator cuff “impinges” on the coracoacromial arch.
Neer classification (2):
- Stage I:
  - Acute inflammation, edema, and hemorrhage
  - Usually reversible with nonoperative treatment
- Stage II:
  - Continuum from stage I
  - Progression of rotator cuff abnormalities to fibrosis and tendinitis
  - Less likely than stage I impingement to respond to nonoperative management
- Stage III:
  - Rotator cuff tears and changes to the coracoacromial arch
  - Spurs form along the anterior–inferior acromion (“hooked acromion”)
Internal impingement:
- Occurs primarily in overhead and throwing athletes
- The posterior supraspinatus and
  infraspinatus tendons are pinched between the humeral head and
  posterior glenoid during maximum abduction and external rotation, as
  seen in throwing.
Secondary impingement: Dynamic
impingement, seen with scapular muscle fatigue, occult shoulder
instability, and rotator cuff dysfunction (Improper shoulder mechanics
leads to dynamic impingement of an intact rotator cuff under an
otherwise normal coracoacromial arch.)
Synonyms: Subacromial bursitis, Subacromial impingement, Rotator cuff tendinitis

General Prevention

Proper overhead mechanics

Epidemiology

Common after the age of 50 years
Equally as common in males as in females

Incidence

May occur at any age
Increasing incidence with increasing age, likely secondary to degenerative changes in the rotator cuff (3)
Bone spurring of the acromion, which is
associated with impingement syndrome, is 4 times more likely in
patients >50 years old (3).
Internal impingement and secondary
impingement from glenohumeral instability can cause shoulder pain in
the younger patient (<40 years old), especially in overhead athletes
(pitchers, tennis players, swimmers, etc.).

Prevalence

Very common

Risk Factors

Increasing age (>50 years)
Overhead athletics and occupations
Instability
Hooked acromion
Os acromiale (failure of the acromion to fuse after birth)
Trauma

Genetics

No known inheritance patterns

Etiology

The pinching of the subacromial soft
tissues between the humeral head and coracoacromial arch is the primary
cause of the inflammation.
- Commonly seen in patients with a type III hooked acromion
- In addition to a congenital type III
  hooked acromion, the hook may be secondary to calcification at the
  coracoacromial ligament from repetitive impingement.
- Mild glenohumeral instability (acquired or congenital) can predispose patients to secondary and internal impingement.
- Overhead activities: Athletics and occupations that require overhead activities (electricians, builders, shelf stockers, etc.)
- Rotator cuff dysfunction or weak cuff
  muscles allow superior migration of the humeral head, narrowing the
  subacromial space with overhead activities.

Associated Conditions

Rotator cuff tears (partial thickness and the continuum to full thickness)
Calcific tendinitis:
- Calcification in rotator cuff tendons from unknown cause
- Typically undergoes spontaneous resorption and healing with time
- Acutely painful during calcium resorption
Biceps tendinitis:
- Inflammation of the tendon of the long head on the biceps
- Incidence increases with rotator cuff disease.
AC arthritis:
- Pain at the AC joint
Adhesive capsulitis:
- Stiff shoulder secondary to capsular fibrosis
Labral tears:
- SLAP tears are common in overhead athletes with internal impingement and in patients with rotator cuff tears

Diagnosis

Signs and Symptoms

Pain with overhead activity of the arm

History

History of pain with overhead activities (combing hair, putting dishes away, etc.)

Physical Exam

Tenderness to palpation over anterior and lateral acromion and rotator cuff
Positive Hawkins sign: Pain with passive flexion and internal rotation
Positive Neer sign: Pain with passive flexion of shoulder while scapula is stabilized
Painful arc: Arc where pain occurs with active abduction
Decreased active and passive forward flexion and abduction secondary to pain
Pain with infraspinatus and supraspinatus muscle testing

Tests

Impingement test:
- Inject 10 mL of 1% lidocaine into the subacromial space with sterile technique.
- Wait 5–10 minutes and repeat the shoulder examination.
- Positive test: Improvement in symptoms

Imaging

AP or 30° caudad angled AP view (Grashey view):
- Subacromial sclerosis (eyebrow sign)
- Greater tuberosity cyst
- Superior migration of humeral head
Supraspinatus outlet views:
- Acromial morphology (hooked acromion)
MRI:
- Helpful in delineating injury to rotator cuff

Pathological Findings

Degenerative changes in rotator cuff tendons
Inflammation and fibrosis of the subacromial bursa

P.395

Differential Diagnosis

Rotator cuff tears:
- May be partial or full thickness
- Weakness and pain with supraspinatus and infraspinatus muscle testing
- Drop arm test: Inability to hold arm abducted
- MRI >1.5 tesla magnetic and shoulder coil is the best diagnostic test.
Calcific tendinitis: Calcification of cuff tendons seen on radiographs
Biceps tendinitis:
- Tender to palpation along the biceps tendon
- Positive Speed (resisted shoulder flexion with palm up) and Yergason (pain with resisted supination) tests
Cervical spine:
- Any pain that is distal to elbow should raise concern for a cervical spine cause.
- Always perform a thorough neurovascular examination.
- Cervical spine imaging
AC arthritis:
- Localized pain at AC joint
- Pain with passive cross-body arm adduction
- Degenerative changes seen on radiographs
- Pain improved with injection of lidocaine into the AC joint
Glenohumeral instability:
- Apprehension and relocation tests
- Sulcus sign (passive inferior subluxation of humeral head)
Glenohumeral arthritis:
- Decreased active and passive ROM with crepitance and pain
- Degenerative changes in glenoid and humeral head on radiographs
Adhesive capsulitis:
- Decreased ROM, especially external rotation
- Decreased ROM (active, passive)
- Pain at extremes of motion
SLAP lesion:
- Tear at superior labrum at insertion of biceps tendon
- Positive O’Brien test
- MRA is the best diagnostic test.

Treatment

General Measures

Initial nonoperative management trial before surgical intervention is successful in ~70% (4).

Activity

No shoulder abduction or flexion >60° during early inflammatory stage

Special Therapy

Physical Therapy

Improves ROM, particularly internal rotation
Rotator cuff program
Strengthening:
- Work in pain-free ROM
- Scapular stabilizers
- Rotator cuff muscles
- Help keep humeral head within glenoid
Ice, ultrasound, electrical stimulation

Medication

First Line

NSAIDs

Second Line

Subacromial corticosteroid injections

Surgery

Indicated if symptoms continue after 6 months of a well-designed and monitored nonoperative regimen
Open or arthroscopic acromioplasty and subacromial decompression:
- Successful in ~75–90% of cases (5,6)
- Currently, an arthroscopic procedure is the most common technique:
  - Remove inflamed subacromial bursa.
  - Resect undersurface of acromion and acromial hook.
  - Can resect distal clavicle for AC arthritis
  - Affords visualization of the glenohumeral joint to determine if additional intervention is needed
- Open acromioplasty:
  - Less commonly used, unless used with an open rotator cuff repair
  - If the deltoid attachment is mobilized, care must be taken to repair it adequately
- Early ROM is critical for avoiding a stiff shoulder.

Follow-up

Prognosis

Success rate with nonoperative treatment: ~70% (4)
Success rate of acromioplasty in those for whom nonoperative treatment fails: ~75–90% (5,6)

Complications

Surgical:
- Failure to resolve symptoms:
  - Inadequate resection of acromion
  - Incorrect diagnosis: AC arthritis, glenohumeral arthritis
- Stiff shoulder:
  - Postoperative adhesions
  - Inadequate postoperative arm mobilization
- Infection
- Hematoma
Progression of impingement:
- Rotator cuff tear
- Cuff arthropathy
- Tearing of proximal tendon of long head of the biceps (“Popeye arm”)

Patient Monitoring

Close outpatient follow-up to monitor ROM

References

1. Vecchio P, Kavanagh R, Hazleman BL, et al. Shoulder pain in a community-based rheumatology clinic. Br J Rheumatol 1995;34:440–442.

2. Neer CS, II. Impingement lesions. Clin Orthop Relat Res 1983;173:70–77.

3. Nicholson
GP, Goodman DA, Flatow EL, et al. The acromion: Morphologic condition
and age-related changes. A study of 420 scapulas. J Shoulder Elbow Surg 1996;5:1–11.

4. Morrison DS, Frogameni AD, Woodworth P. Non-operative treatment of subacromial impingement syndrome. J Bone Joint Surg 1997;79A:732–737.

5. Hawkins RJ, Plancher KD, Saddemi SR, et al. Arthroscopic subacromial decompression. J Shoulder Elbow Surg 2001;10:225–230.

6. Patel VR, Singh D, Calvert PT, et al. Arthroscopic subacromial decompression: Results and factors affecting outcome. J Shoulder Elbow Surg 1999; 8:231–237.

Additional Reading

Gomoll AH, Katz JN, Warner JJP, et al. Rotator cuff disorders: Recognition and management among patients with shoulder pain. Arthritis Rheum 2004;50:3751–3761.

Matsen FA, III, Titelman RM, Lippitt SB, et al. Rotator cuff. In: Rockwood CA, Jr, Matsen FA, III, Wirth MA, et al., eds. The Shoulder, 3rd ed. Philadelphia: WB Saunders, 2004:795–878.

Michener LA, McClure PW, Karduna AR. Anatomical and biomechanical mechanisms of subacromial impingement syndrome. Clin Biomech (Bristol, Avon) 2003;18:369–379.

Miscellaneous

Codes

ICD9-CM

726.2 Impingement syndrome, shoulder

Patient Teaching

Activity

Proper overhead technique

FAQ

Q: Does shoulder impingement require surgery?

A:
No. Most impingement symptoms improve with a good rotator cuff
rehabilitation program. Subacromial decompression to relieve
impingement is recommended only for shoulders unresponsive to 6 months
of physical therapy.

Q: What are some of the causes of shoulder impingement in patients <40 years old?

A: Common causes in a young patient are occult instability, rotator cuff dysfunction, and os acromiale.