Acromioclavicular Joint Disorders

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Definition/Description

Disorders is a general term to cover a range of conditions. It can be due to trauma, such as joint dislocation of the acromioclavicular joint or degenerative conditions, such as osteoarthritis. An acromioclavicular dislocation is a traumatic dislocation of the joint in which a displacement of the clavicle occurs relative to the shoulder.

Clinically Relevant Anatomy

The acromioclavicular joint is a diarthrodial joint with an interposed fibrocartilagninous meniscal disc that connects the clavicle with the acromion. It has an intra-articular synovium and an articular cartilage interface and is characterised by the various angles of inclination in the sagittal and coronal planes and by a disc. 2 types of disc have been observed; a complete disc (very rare) and a meniscoid-like disc. . The acromioclavicular joint is surrounded by a capsule and reinforced by the superior/inferior capsular ligaments with the coracoclavicular ligaments (trapezoid and conoid) also important structures for stability of the joint. 

The acromioclavicular (AC) ligament and coracoclavicular (CC) ligaments are part of the static stabilisers of the joint. The AC ligament controls horizontal stability in the anterior­posterior plane whilst the CC ligaments serve to control vertical stability. The conoid part of this ligament attaches posteriorly and medially on the clavicle with the trapezoid part attaches anteriorly and laterally. The trapezius and deltoid muscles also provide dynamic stabilisation of the AC joint.

Epidemiology /Etiology

Injuries to the AC Joint account for approximately 10% of acute injuries to the shoulder girdle, with separations of the AC Joint accounting for 40% of shoulder girdle injuries in athletes. Commonly, injury happens when falling onto an outstretched hand or elbow, direct blows to the shoulder, or falling onto the point of the shoulder.

Figure 2 illustrates the common mechanism of injury:
(A) a direct force onto the point of the shoulder
(B) indirect forces to the AC joint can also cause injury. For example, a fall on to the elbow can drive the humerus proximally, disrupting the AC joint. In this case, the force is referred only to the AC ligaments and not the coracoclavicular ligaments.

The injury is frequently seen in hockey and rugby players, but is also seen in alpine skiing, snowboarding, football, cycling and motor vehicle accidents.

Characteristics/Clinical Presentation

With an AC joint injury pain is often felt radiating to the neck and deltoid. The AC joint may also become swollen, the upper extremity often held in adduction with the acromion depressed, which may cause the clavicle to be elevated.

Allman et al described a 3 grade classification with Rockwood and Green expanding this to a 6 grade classification model (known as the Rockwood grades). This classification of AC joint injuries assists in deciding on appropriate treatment options and helps to avoid complications by failure to recognise the pattern of injury.

Rockwood Grades of injury.(AC: Acromioclavicular, CC coracoclavicular)

Grade	Description	Observation/Testing
I	Sprain of AC ligaments. The AC and CC ligaments are intact	No instability of clavicle detected on stress tests
II	AC ligaments are ruptured, CC ligaments are intact. Often described as a subluxation.	Clavicle is unstable to direct stress tests
III	Complete disruption of both the AC and CC ligaments without significant disruption of the delto-trapezial fascia. This is often described as a dislocation.	Deformity present with clavicle appearing elevated (acromion depressed), clavicle unstable in both vertical and horizontal plane
IV	Distal clavicle is posteriorly displaced into trapezius muscle	Posterior deformity present.
V	More severe form of grade III. Complete disruption of both the AC and CC ligaments with disruption of the delto- trapezial fascia.	Pseudo lateral clavicle elevation, downward displacement of the scapular.
VI	Inferior displacement of the distal clavicle, either subacrominal or subcoracoid	Severe trauma, usually accompanied by other significant injuries.

Using digital measurement instead of a solely visual diagnosis is recommended because of the higher intra- and interobserver reliability.

Differential Diagnosis

• Most dislocations are situated in the Glenohumeral joint and 90% of this dislocations are anterior which can cause concomitant pathologies such as a Hill sachs lesion or injury of the brachial plexus.
• Pain in the AC joint from osteoarthritis or disc disease
• Osteolysis of the distal clavicle
• Instability of the AC joint 
• Rotator-cuff impingement or tear 
• Adhesive capsulitis 
• Thoracic outlet syndrome 
• Superior labral tears 
• Complex pain syndrome 
• Shoulder dislocation
• Anterior humerus subluxation

Diagnostic Procedures

• Acromioclavicular dislocation is often diagnosed via radiography. Possible problems can occur with patients suffering from a type I injury as nothing abnormal is evident on a radiograph. Diagnosis is therefore determined by the mechanism of injury and tenderness over the AC joint.
• Resisted AC Joint Extension Test

Outcome Measures

• DASH: Disabilities of the Arm, Shoulder and Hand questionnaires.
• Simple Shoulder Test questionnaires: Purpose is to assess functional disability of the shoulder, scored from 12 questions: 2 about function related to pain, 7 about function/strength and 3 about range of motion
• Shoulder Pain and Disability Index (SPADI): The primary outcome measure is the patients’ perceived level of pain and disability. It consists of 2 subscales, pain and disability, which are combined to produce a total score ranging from 0 (no pain or functional difficulty) to 100 (highest level of pain and functional difficulty). The SPADI is reliable, valid, and responsive for shoulder pain of musculoskeletal, neurogenic, or undetermined origin.
• American Shoulder Elbow Surgeon (ASES): This measures functional limitations and pain in patients with musculoskeletal shoulder pathologies. The functional score is calculated from 10 questions relating to function using a 4 point scale.

Examination

• AC Joint Palpation for Tenderness
• O’brien test: Examination using the O’Brien test tightens the posterior capsule and posteriorly translates the humeral head, stressing the labrum resulting in pain and weakness.
• Paxinos sign: Provocative testing for acromioclavicualr joint injury . Walton et al found that the Paxinos test is a good clinical diagnostic tool and bone scanning is the most reliable imaging modality for the diagnosis of AC joint pathology. When both of these tests are positive, there is a high degree of confidence for a diagnosis of AC joint pathology .
• Test of Stenvers 4: Clavicular Roll
• Resisted AC Joint Extension Test

A history of the mechanism of injury and palpation of the AC joint help to differentiate between a type I and a type II injury. A minor deformity in the AC joint is indicative of a type II injury. In a type I injury, swelling is usually present with pain on abduction of the arm, whereas with a type II pain is usually experienced in all movements of the arm. An obvious step deformity of the AC joint indicates a type III injury and the patient usually supports the injured arm as close as possible to his body.

Medical Management

Treating an AC joint injury will vary depending on its severity.

Nonoperative treatment is recommended for type I and type II AC separations, but for type III this is still much debated, as there is a high chance of early onset degenerative within the joint. However surgical intervention may be chosen as in certain cases this may yield better functional results, especially where the patient is younger, highly active or where a type III injury does not respond to conservative management. For type IV and V surgical repair is highly recommended.

There are several surgical methods, but the 4 most common surgical options are:

• AC joint fixation using hook-plates
• coracoacromial ligament transfer
• coracoclavicular interval fixation
• a coracoclavicular ligament reconstruction. 

Physical Therapy Management

Conservative - Types I and II

Initial treatment should adhere to the POLICE protocol including protection, optimal loading, ice, compression, elevation and referral within the first 48 hours. A sling should be used to immobilise the shoulder along with keeping the shoulder in a elevated position when at rest. Taping to help support the joint can also be useful.

A sling can be in situ until the pain subsides. Return to normal activities is normally around 2-4 weeks for a type I injury, 4-6 weeks for a type II and 6-12 weeks for a type III. For patients whose symptoms do not improve within this frame, intra-articular steroid injections may be indicated

There is, however, a lack of evidence regarding rehabilitation protocols. Reid et al developed a best practice guideline after a systematic review of current practice

Acute Phase

Range of motion (ROM): passive, active-assisted, active

• Glenohumeral Joint (GHJ): Internal rotation, external rotation, flex to tolerance : towel slides, pendular exercise

• Scapula: protraction, retraction, elevation, depression
• Active-assisted exercise using a L bar for Internal and external rotation: GHJ 30° to 45° abduction, 30° to 40° forward flexion:

Soft tissue: manage tightness

• Pectoralis minor stretch 
• Posterior part of the GHJ: sleeper stretch
  

Isometric exercises: should be multi-angle, submaximal and subpainful

Closed Kinetic Chain: (no weight)

• hand supported in various planes and levels of elevation, control scapula position and progress to 90°
• elbow supported internal rotation/external rotation
• wall slides, scapula clock
• push-ups on wall

Recovery Phase

Avoid aggravation of the injury: example of exercises are bench press, prone press-ups, shoulder press or dips. Proximal stability must be reached before strength.

Range of motion: regain full range of motion of GHJ (including horizontal adduction), IR/ER at 90° abduction GHJ and capsular stretches.

Closed kinetic chain: increase the loads of previous closed kinetic chain exercises. Add active arm elevation and rotation.

Axial loaded active ROM (transition from closed kinetic chain to open kinetic chain (OKC)):

• wall slides with trunk and lower limb work 
• wall slides in the scapular plane
  

Kinetic chain:

• trunk and hip extension (scapular retraction) e.g. low row exercises

• trunk and hip flexion (scapular protraction) e.g. punches
  
• bilateral and unilateral pull with trunk rotations, e.g. upper cuts
  
• Deltotrapezial complex work : exercises with cables, shrugs, abduction at various angles
  
  
  

Plyometric exercises (dynamic stretch shortening): medicine ball toss and catch, tubing plyometric exercises. Sport specific exercises: a two-hand overhead side to side throw for the overhead athlete.

Return to sport

Return to sport guideline:

• Grade I: 2-4 weeks
• Grade II: 4-8 weeks
• Grade III: 6-8 weeks
  

Post Operative - Types V and VI

Type V and VI are considered to require surgical repair and physical therapy may follow various post surgical protocols.

Studies comparing the results of non-operative and surgical treatment of type III AC separations have shown that surgical interventions do not have a substantial benefit. Bannister et al concluded that conservative management of type III injuries yielded a return to full shoulder kinematics more quickly with less complications. Conservative management should be considered as the first line of treatment for type III separations

For type IV and V injuries there is no evidence based literature recommending a specific treatment for these injuries. Surgery is the preferred treatment, but there has been a reported case of the successful use of manual reductions, which converted the type IV to a type II. 

Goals post surgery

1. Control pain and swelling
2. Protect the AC joint repair
3. Protect wound healing
4. Begin early shoulder motion

Post surgical management

1. Apply cold packs to the operated shoulder to reduce pain and swelling.
2. Remove the sling several times a day to gently move the arm in a pendulum motion: lean forward and passively swing the arm.
3. Apply cold to the shoulder for 20 minutes at a time as needed to reduce pain and swelling.
4. Remove the sling several times a day: move the elbow wrist and hand. Lean over and do pendulum exercises for 3 to 5 minutes every 1 to 2 hours.
5. To wash under the operated arm, bend over at the waist and let the arm passively come away from the body. It is safe to wash under the arm in this position. This is the same position as the pendulum exercise.
6. Protocols on active movement and sling use will vary depending on the surgeon and the procedure done. Some will prescribe no active arm movements and the need for a sling for up to 6 weeks. Others may allow sling use as needed and active movement immediately, for example up to 90 degrees in the first two weeks slowly progressing from there.

Post-operative rehabilitation then follows similar guidelines as that for Type I and II injuries. Treatment consists initially of ROM exercises, followed by progressive strengthening. Rehabilitation needs to be followed through to full strength and mobility in order to avoid incidence of persistent pain and instability of the AC joint.