Acromioclavicular Arthritis

Original Editor - Manisha Shrestha Top Contributors - Manisha Shrestha, Lucinda hampton, Kim Jackson and Jacob Bischoff

Original Editor - User Name

Top Contributors - Manisha Shrestha, Lucinda hampton, Kim Jackson and Jacob Bischoff  

Introduction

Osteoarthritis is the most common cause of shoulder pain originating from the acromioclavicular (AC) joint. It is a frequent finding in middle-aged people. Most of the patients are asymptomatic, and they may present as an incidental finding in shoulder X-Ray or Magnetic resonance imaging (MRI). Patients may present with complaints of pain over the joint while doing overhead and cross-body activities. Pain and dysfunction of ACJ origin may lead to an inability to perform manual labor tasks and sports and difficulty with activities of daily living. Functional limitations of ACJ pain include difficulty with resistance-training activities that place the glenohumeral joint in an extended position.

AC joint arthritis is caused due to early degeneration of the cartilage and intraarticular disc. Arthritis is often associated with distal clavicular osteolysis. Damage to the ACJ can be synchronous with damage to the supraspinatus tendon and osteophytes from the arthritic joint may contribute to subacromial impingement exacerbating and producing further shoulder pain.

Clinically Relevant Anatomy

The ACJ is a synovial joint that provides the scapula with additional range of rotation on the thorax, which allows the scapula to adjust outside of its initial plane (posterior tipping and internal rotation) to follow the changing shape of the thorax as arm movement occurs.

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Epidemiology

12-month prevalence of shoulder pain has been estimated to be 30%, which is second only to low back pain.

Acromioclavicular joint (ACJ) disease is reported to be present in 31% of all patients with shoulder pain.

The incidence of ACJ pain is reported to be between 0.5 to 2.9/1000/year in primary care.

Etiology

Type of AC joint arthritis: based on the etiology

1. Primary osteoarthritis: It is articular degeneration without any apparent underlying cause. It more commonly affects the AC joint than a glenohumeral joint. It develops as a consequence of constant stress on the joints, often in people who perform repeated overhead lifting activities.
2. Secondary osteoarthritis: It is due to other associated causes like post-trauma or other underlying diseases such as rheumatoid arthritis. Post-traumatic AC joint arthritis is even more prevalent due to the high incidence of injury to the joint. Arthritic symptoms have been demonstrated in Grade I and II sprains of the AC joint in 8% and 42% of patients, respectively.

Diagnosis

Accurate diagnosis and localization of pathology to the AC joint is vital in determining the correct treatment protocol in order to avoid persistent shoulder pain. The proper diagnosis of acromioclavicular joint osteoarthritis requires a thorough physical exam, plain-film radiograph, and a diagnostic local anesthetic injection.

History

• History of trauma: direct impact on the joint or a fall on an outstretched arm.
• Occupational history: an occupation that requires repeated overhead lifting activities,

On examination

The cross-over adduction test is performed by the motion of forward flexion to 90° with horizontal adduction of the arm across the chest. Reproducible pain over the joint suggests AC joint involvement.

• Patients often present with an intact range of motion with the exception of cross-body adduction, behind the back motions, and overhead reaching, which all produce pain localized to the AC joint.
• Localized superior shoulder pain,
• AC joint may be tender to palpation.
• Pain elicited to the deltoid area by the motion of forward flexion to 90° with horizontal adduction (cross-over test) or straight-ahead pushing (as in the bench press exercise).
• Possibly swelling in the presence of distal clavicle osteolysis

• The most sensitive tests for ACJ pain are acromioclavicular point tenderness and the Paxinos test.
• Resisted AC joint extension test also helps to identify AC joint pathology.
• Acromioclavicular joint involvement can be confirmed by an injection of a local anesthetic. Injection of 0.5–2 mL of 1% or 2% lidocaine or 0.5 mL of 0.25 or 0.5% bupivacaine into the AC joint should provide a significant reduction in symptoms. A continuation of pain following anesthetic injection suggests other shoulder pathologies, most commonly rotator cuff injury.
• Radiographic images:
  • are the initial diagnostic imaging modality of choice, with anterior-posterior views demonstrating degenerative changes, subchondral cysts, sclerosis, osteophytes, and joint-space narrowing.
  • The Zanca view, which consists of angling the X-ray source 10–15° superiorly and decreasing the kilovoltage to 50% standard exposure, is helpful in evaluating AC joint pathology by allowing visualization of distally projecting osteophytes of the acromion.
  • Magnetic resonance imaging has the ability to detect capsular hypertrophy, effusions, and subchondral edema.

Differential Diagnosis

• Calcific tendonitis
• Glenohumeral arthritis
• Adhesive capsulitis
• Rotator cuff impingement syndrome

Management

The management of ACJ pain appears to be determined by the degree of pain and disability.

Surgical

Surgical treatment is only recommended if conservative treatment fails to provide adequate pain relief and persistent symptoms continue to interfere with activities of daily living after 6 months of intensive non-surgical treatment.

Distal clavicle excision (DCE):

• • It is an operative approach also known as the “Mumford” procedure and is commonly performed.
  • It was initially performed as an open procedure, first described in 1941 but now is performed arthroscopically.
  • The procedure aims to produce a ‘gap’ between acromion and clavicle and involves resecting bone mainly from the distal end of the clavicle without compromising joint stability.
  • Open surgical complications for these procedures occur in 0% to 64% of cases and include infection, heterotopic ossification, joint instability, suprascapular neuropathy, and distal clavicle fracture, in addition to complications associated with anesthesia. Other complications include weakness of the deltoid and trapezius muscles and clavicular instability.
  • Eskola et al investigated long-term results of patients managed with DCE for complaints of ACJ pain and reported that nearly 1 in 3 patients had poor long-term outcomes and advised against DCE for patients with higher functional demands on their shoulders.

Non- Surgical/ conservative

Non-operative management is usually considered first, with activity modification, physical therapy modalities, oral analgesics, and injections of corticosteroid and local anesthetic all being options.

Local corticosteroid injection

Injections of 0.25–0.5 mL of betamethasone sodium phosphate and acetate or 0.25–0.5 mL methylprednisolone, 40 mg/mL are recommended. Limits of two to four injections per year with a total of twenty are recommended, as excessive corticosteroid administration may cause subcutaneous fat atrophy and dermal thinning. It is suggested that injections can provide good pain relief and be a helpful diagnostic test, but seem to be ineffective as a long term therapy.

Activity modification

It includes avoidance of repetitive motions causing the pain, such as push-ups, dips, flies, and bench press exercises.

Evidence

A prospective single-cohort study conducted by Harris et al. in 2012 regarding the effect of manual therapy in non-acute AC arthritis pain. It showed a statistically significant and clinically meaningful improvement in both functional and clinical outcome measures at 4 weeks and 6 months following manual therapy.

A scoping review published in 2017

• reveals a lack of primary evidence regarding treatments and treatment pathways for ACJ pain. At no point have arthroscopic surgery, open surgery, steroid injections, and rehabilitation programs been compared directly.
• also shows making it difficult to delineate the cause of shoulder pain and the effectiveness of subsequent treatments as some bias was introduced by the fact that many patients with ACJ pathologies also had other concomitant shoulder pathologies, such as rotator cuff tears.