Acromioclavicular Joint

The Acromioclavicular, orAC, joint is a plane, triaxial joint with an often absent articular disc. It is one of the 3 ‘true’ joints included in The Shoulder Girdle . The articulation is formed between the lateral end of the Clavicle and the Acromion of the Scapula . In contrast to the Sternoclavicular Joint , the AC joint permits subtle and slight movements of the Scapula , ultimately assisting the Scapulothoracic Joint . Range of Motion at the AC joint is difficult to measure and rarely recorded.

Key Structures

Bone

Muscle

Connective Tissue

Nerve

Fascia

Kinematics

The Acromioclavicular Joint liberates movement of the Scapula from that of the Clavicle ; however, the extent to which is limited by a small articular surface, dynamic and static stabilisers and, when present, the fibrocartilaginous disc that resides within the joint space. Movement at the Acromioclavicular Joint is reliant on coupled motion at the Scapulothoracic Joint and Sternoclavicular Joint where it permits subtle adjustments to overal motion of The Shoulder Girdle . Three degrees of Scapula movement are described to occur about the lateral Clavicle (SOURCE-21):

When elevating the arm from 0-90º in the scapular plane, Scapula motion generally represents a composite of upwards rotation, internal rotation and posterior tilting (SOURCE-21). During elevation in the coronal plane ( GH Joint - Abduction ), the Clavicle elevates ~11-15º relative to the Thorax and retracts 15-29º (SOURCE-20). The translational capacity of the lateral Clavicle appears similar in all directions, with a consistent external force resulting in 5.1mm of posterior translation, 5.6mm anteriorly and 4.2mm inferiorly (SOURCE-22).With their fixed position medial of the Acromialclavicular Joint, the Coracoclavicular Ligaments (in particular the Conoid Ligament ) anchor the Coracoid Process to the Clavicle which serves to synchronise motion of the Scapula with arm motion (SOURCE-20). In this sense during arm elevation, upwards rotation of the Scapula occurs about Coracoclavicular Ligaments rather than the Acromioclavicular Joint (SOURCE-20)

Fibrocartilaginous Disc

An often transient intra-articular Fibrocartilaginous Disc resides between the joint surfaces and is continuous with the joint capsule (SOURCE-18). Its flexible, Menisci -like structure serves to cushion the joint and improve joint congruency (SOURCE-18). The discs transient nature is attributed to its fragility, where the centre of the disc perforates leaving it worn, fragmented or absent depending on the extent of degeneration (SOURCE-4+6+18+26). In younger individuals the disc is likely complete and fully functioning but by the second decade of life it may display degenerative changes to the extent that in older populations only ~10% of complete discs remain (SOURCE-4+18+26). The presence of nerve fibres within the intra-articular disc suggest it may be an independent source of Pain (SOURCE-25).

Stabilisers

The intricate balance between the Acromioclavicular Joints dynamic and static stabilisers forms a crucial regulator of the joints available movement. In anatomical positon the joint is least congruent with the capsule and ligaments relaxed, while the closed-packed position where the joint is maximally compressed and capsuloligamentous structures pulled taut occurs at 90º GH Joint - Abduction (SOURCE-6).

Static Stabilisers

Non-contractile ligament ous structures afford the Acromioclavicular Joint static stability or ultimate limits to the joint to prevent excessive translation, rotation or Dislocation . In theory each stabiliser serves to constrain a particular direction; however, for the ligamentous structures of the Acromioclavicular Joint, it appears each stabiliser has more than one contribution that is contingent on the direction and extent of Clavicle displacement (SOURCE-18):

  • Acromioclavicular Joint Capsule - while the joint capsule and Acromioclavicular Ligaments are often described as a single complex, the capsule is a continuous fibrous sheath that envelopes the entire articulation while the Acromioclavicular Ligaments are localised thickenings that reinforce the capsule. This continuity is functionally demonstrated by the fact that tensile/ shear forces from superior loading are shared equally between the superior and inferior capsular regions (SOURCE-22).The joint capsule is lined internally by a synovial membrane, which affords the synovial fluid required for movement but leaves the Acromioclavicular Joint more susceptible to inflammatory/ infectious pathologies (SOURCE-5+24)

  • Acromioclavicular Ligaments - these ligaments represent localised thickenings that reinforce the joint capsule. Most often this set of ligaments are described as four distinct portions (superior, inferior, anterior and posterior), although some have limited description to Superoposterior and Anteroinferior bundles to reflect their primary functions resisting posterior and anterior displacement of the Clavicle , respectively (SOURCE-18+20). An anterior load to the Clavicle , resulting in its posterior displacement, is resisted primarily by the superior portion (~56% of total resistance) with contributions from the posterior portion (~25%) (SOURCE-20). Conversely a posterior load, resulting in anterior displacement to the Clavicle , is resisted initially by the inferior portion and with larger force the superior portion and the Trapezoid Ligament equally (SOURCE-20+22)

  • Coracoclavicular Ligament - this is a complex of two distinct ligaments, the Trapezoid Ligament and Conoid Ligament , which span between the Clavicle and the Coracoid Process of Scapula and form the chief vertical stabilisers (SOURCE-18+20+22). The Trapezoid Ligament is situated anterolateral of the Conoid Ligament , with both positioned posterior of the Pectoralis Minor attachment on the Coracoid Ligament (SOURCE-20). Their courses and nearly perpendicular fibre orientation enable these ligaments to serve collective and independent roles depending on the direction and degree of Clavicular displacement (SOURCE-20). Collectively the Coracoclavicular Ligaments serve as the primary resistance to vertical (superior or inferior) translation of the Clavicle , where the Conoid Ligament plays a minimal role in small amounts of superior translation yet is the predominate resistance with large translations (SOURCE-18+20+22). Together these ligaments also have the capacity to resist external rotation and horizontal (anteroposterior) displacement, which may serve a compensatory role when the joint capsule is compromised (SOURCE-4+6+7+18). Additionally through linking the Clavicle to the Scapula , these ligaments help guide the synchronous Scapulohumeral Rhythm (SOURCE-20). Independently the Trapezoid Ligament forms a notable restraint to compressive forces and horizontal displacement (SOURCE-18+20+22)

Dynamic Stabilisers

With their extensive attachment to the Clavicle and Scapula , dynamic stability for the Acromioclavicular Joint is afforded by the Deltoid and Trapezius which support the weight of the arm that would otherwise place significant stress on the joint (SOURCE-16+18+20+21). Bony attachment is achieved through both muscular and Fascia l fibres (SOURCE-18). Notable attachment is made via the superficial aponeuroses of these Muscles which form theDeltotrapezial Fasciathat adheres to the Periosteum of both the Clavicle and Acromion (SOURCE-18+20). The Deltotrapezial Fascia also blends with the Superior Acromioclavicular Ligaments which reinforces the articulation, particularly when these muscles are stretched or contract (SOURCE-18+20+21). The Serratus Anterior is also described to compliment stability of the Acromioclavicular Joint through a force-coupling formed with the Trapezius (SOURCE-16+20).

Variation

  • the Coracoclavicular Joint ~1% of the population have an additional articulation between the Clavicle and the dorsomedial portion of the Coracoid Process (SOURCE-15)

Pathomechanics

The most notable pathologies of the Acromioclavicular Joint are typically derived from an acute traumatic event or a chronic degenerative process with the potential for either to predispose the other.

Instability

The ligaments of the Acromioclavicular joint are pulled taut at the extremes of many motions of The Shoulder Girdle ; however, the direction of joint instability may implicate certain tissues over others (SOURCE-5+6):

  • Anteroposterior Instability - is predominately attributed to laxity in the intrinsic Acromioclavicular Ligaments which are often the first to fail when the joint is excessively stressed

  • Superoinferior Instability - is predominately attributed to laxity in the extra-articular Coracoclavicular Ligament s

Compromise of a single ligamentous component or the fibrocartilagnous disc may not disturb the suspensory complex of The Shoulder Girdle ; however, disturbance of a combination is likely to lead to instability, Dislocation and a sequela of (SOURCE-8):

Compromise of these ligaments and consequent Dislocation of the Acromioclavicular Joint is most often attributed to a direct blow/ fall on the lateral aspect of The Shoulder Girdle while the arm is in GH Joint - Adduction , causing the Acromion to be driven inferomedially (SOURCE-8+11). A FOOSH mechanism has also been reported (SOURCE-8). The extent of injury and number of soft-tissues implicated is generally correlated with the significance of force bestowed upon the shoulder. Initially the Acromioclavicular Ligaments are compromised as the Acromion/ Scapula is displaced inferiorly while inferior motion of the Clavicle is blocked by its attachment on the First Ribs (SOURCE-11). As one of the strongest ligaments in the body, greater force transmission is required to compromise the Coracoclavicular Ligament which results in further displacement of the Clavicle from the Acromion (SOURCE-11). Eventually force may be so significant that it drives the lateral Clavicle through the Deltoid and Trapezius which also severs their attachment (SOURCE-11).In children Acromioclavicular Joint injury, particularly Dislocation , is rare. More often a “pseudodislocation” may occur where the Epiphyseal is torn from the distal Clavicle and the Periosteal Sleeve is Fracture d (SOURCE-8).

Classification

While other imaging modalities such as CT and MRI may afford a much clearer visualisation of Acromioclavicular injury, they fail to provide a framework which directs treatment. The Rockwood system utilises the bony displacement visible on Radiographs (X-Rays) to infer the extent of soft-tissue damage and classify it so it may be correlated with a treatment algorithm (SOURCE-11+12+15):

Degeneration

There are several avenues by which degeneration of the Acromioclavicular Joint may develop and numerous pathologies a degenerative state predisposes (13+14+15+16+17+18):

  • Intra-Articular Disc Degeneration - degenerative changes of the fibrocartilaginous disc typically begin by the second decade of life, as indicated by the presence of frays, Tear s, holes and defects in the Chondral surface which predispose Osteoarthritis

  • Post-Traumatic Arthropathy - the repair process following a traumatic event is impaired, predisposing Osteoarthritis and other pathology through diverging mechanisms:

    • Repeated Stress - following a pathway similar toDistal Clavicle Osteolysis, where repetitive stress causes microtrauma/ Fractures of the Subchondral Bone of the Distal Clavicle Head. Despite continued attempts to the repair damage there is a net increase in Osteoclasts activity which ultimately leads to bone degradation, subchondral cystic changes and disruption of the articular Cartilage

    • Bony Morphology - ongoing attempts to repair continued damage leads to maladaptive Bone formation and other bony morphologies which narrow theSupraspinatus Outlet- the opening by which the Supraspinatus passes. Under these conditions or by consequence of age, Bone Spurs (orOsteophytes) may form on the undersurface of the Distal Clavicle or Acromion of Scapula and encroach on the limited outlet space which predisposes Subacromial Impingement and Rotator Cuff pathology. Another potentially degenerative change that may invade the Supraspinatus Outlet is the orientation/ angulation or shape of the Acromion. Those that have a more downwards slope towards their lateral end or are longer narrow the outlet and appear to succumb to a similar sequelae as bone spurs. Bony changes may also be extended to neighbouring soft-tissue. Calcification or Ossification of Coracoclavicular Ligament , for example, is a common sequelae of traumatic injury that results from the body’s overzealous attempt to repair the soft-tissue damage with Bone

  • Inflammation Arthropathy - either local or systemic immune responses that cause degenerative changes in the Acromioclavicular Joint. While considered rare and occurring predominately in the immunocompromised, Septic Arthritis is an acute local infection described to rapidly destruct the Acromioclavicular Joint. Due to a small volume/ surface area, this joint is said to be left particularly vulnerable to the conditions degenerative effects. Systemic inflammatory diseases such as Rheumatoid Arthritis or Psoriatic Arthritis may also lead down degenerative avenues including Synovitis , erosions and Bone Marrow/ Soft-Tissue enveloped edema. Rheumatoid Arthritis may cause bilateral Distal Clavicle Osteolysis; however, unlike its trauma-derived counterpart, systemic inflammatory diseases are typically “Pan-Articular” in that they affect the entire joint, implicating the capsule and Cartilage of both the Clavicle and Acromion. The extent of degeneration may reflect the disease progression as the inferior portion of the joint is typically affected first

  • Altered Joint Mechanics - often in the form of instability or Subacromial Impingement , has the capacity to reduce joint congruency, increase contact stresses and alter Range of Motion . These factors serve to compromise vulnerable structures such as the Rotator Cuff , which further perpetuate altered joint mechanics and joint degeneration. For those under the age of 50, Acromioclavicular Joint degeneration is often associated with concomitant Glenoid Labrum Tears which are thought to share a traumatic onset. These Tears are thought to be a source of degeneration in younger individuals

Referred Pain

The Referred Pain pattern for the AC joint includes the lateral neck and Trapezius (SORUCE-1). The presence of nerve fibres within the intra-articular disc suggest it may be an independent source of Pain (SOURCE-25).

Fascia

The following Fascia l continuities contain structures either directly or indirectly involved in Acromioclavicular motion:

Dysfunction at any point along either chain or line can result in altered mechanics and Pain or other symptoms at the Acromioclavicular Joint.

Prevalence

Roughly 9% of all traumatic injuries to The Shoulder Girdle implicate the Acromioclavicular Joint, most often through minor Strains (SOURCE-19+20). Other common injuries include distal Clavicle Fracture s, arthrosis and osteolysis (SOURCE-21). The more severe Acromioclavicular Joint Dislocation has an overall incidence of 3-4 per 100,000 persons in the general population with 25-50% occurring during sporting activities (SOURCE-11). Contact sports such as american football have a considerably stronger association with dislocations with ~40% of players will experience an Acromioclavicular Joint dislocation in their career (SOURCE-23). Incomplete dislocations are twice as common as complete dislocations with either being five-fold more common in men than women (SOURCE-19+20). The majority of traumatic Acromioclavicular Joint injury occurs between 20-30 years of age (SOURCE-19+20).

Pathology

Many pathologies associated with the Acromioclavicular Joint are interrelated, where trauma may lead to a degenerative state or vice-versa. As trauma is often the mechanism behind the joints injury, it may also occur concomitantly with several other pathologies of The Shoulder Girdle (SOURCE-8+11).

Rotator Cuff Tear - shares several relations with Acromioclavicular Joint pathology. For one, degenerative Osteophyte (bone spur) formation on the undersurface of the Acromion and other means of narrowing the subacromial space predispose tears of the cuff. Pathologic states of these two structures may often occur concomitantly as they may be derived from the same degenerative or traumatic mechanism. Similarly, a Rotator Cuff tear which is associated with Scapular Dyskinesis may lead to abnormal joint stresses and accelerated degeneration.

Glenoid Labrum Tear - labral injuries such as SLAP Lesions often occur concomitantly with Acromioclavicular Dislocations through shared mechanisms (SOURCE-27)

Osteoarthritis - degenerative changes such as a loss of intra-articular disc and protective Cartilage may lead to Pain ful Bone -on- Bone contact, making age a major risk factor (SOURCE-28). Osteoarthritis may also be a long term consequence of traumatic injury which serves as a catalyst to the accumulation of micro-trauma and Inflammation (SOURCE-28)

Subacromial Impingement - as detailed throughout thepathomechanicssection, impingement shares a bidirectional relationship with Acromioclavicular Joint pathology where either may predispose the other.

Sternoclavicular Joint Dislocation - simultanous dislocation at either end of the Clavicle , known as bipolar seperation or “floating” (SOURCE-29)

Neuropathy - there are several nervous structures that may be related to Acromioclavicular Joint Pain .

Differential Diagnosis

Acromioclavicular Joint pathology may share similar symptoms to the following pathologies (SOURCE-15+16):

Assessment

Observation

  • Step Deformity- presence of a step deformity at the joint indicates a Coracoclavicular Ligament and/ or Acromioclavicular Ligaments Tear (SOURCE-6+11)

  • Fountain Sign- degeneration at the AC joint causes local swelling/ Inflammation of the local Subacromial Bursa (SOURCE-6+16)

  • For structural compromise Pain is often felt local to the joint and provoked from extreme shoulder ranges, particularly Horizontal GH Joint - Adduction and Elevation (SOURCE-6+8). Conversely, degenerative pathology appears more to refer towards the superoanterior shoulder, anterolateral neck and deltoid and over the Trapezius (SOURCE-11+13+16)

  • Degeneration may be associated with mechanical symptoms such as crepitis, catching or grinding within the joint (SOURCE-16)

  • Acute Dislocations are likely to complain of significant Pain while late stage Dislocations may report of nagging Pain along the medial Scapula , a consequence of Scapular Dyskinesis (SOURCE-11)

Range of Motion

While Range of Motion of The Shoulder Girdle is often unaffected with Acromioclavicular Joint pathology, the following ranges may be provocative (SOURCE-6+8+11+13):

Roughly 20% of those with injury to the Acromioclavicular Joint have a stiff shoulder which is often attributed to concomitant injury such as Rotator Cuff pathology (SOURCE-11). The amount and quality of movement should be compared to the asymptomatic side.

Orthopaedic Testing

The following Shoulder - Special Tests may be relevant in AC joint pathology:

Palpation

  • Joint Line Tenderness - sensitivity 0.48 and specificity 0.60, which significantly increases when performed with Modified O’Brien’s Test (SOURCE-2)

Imaging

There are several imaging modalities that may be useful in the evaluation of Acromioclavicular pathology:

Radiography (X-Ray)- typically the initial imaging technique used as it is often sufficient for the diagnosis and classification of Acromioclavicular Joint injury (SOURCE-8+19). Roughly 1/2 to a 1/3 of the voltage/ x-ray penetration used for the Glenohumeral Joint should be applied to avoid overexposure (SOURCE-20+28). The normal joint space of 1-3mm reduces with age related deterioration while theCoracoclavicular Interspace(distance between the Clavicle and Coracoid Process) increases by 25-50% with ligamentous compromise (SOURCE-11+20). Aside from spacing, x-rays may also reveal swelling and osteopenia (SOURCE-18). The following views may be indicated (SOURCE-8+10+11+20):

  • Standard Viiews

    • True AP

    • Scapular Y

    • Zanca - considered the most accurate view for the Acromioclavicular Joint with a 10-15º tilt of the X-Ray beam in the cephalic direction. Bilateral Zanca views on a single plate significantly improves reliability for the Rockwood Classification system, in particular for assessing the severity of vertical instability. The bilateral view also allows for direct comparison of Coracoclavicular Interspace between the symptomatic and asymptomatic sides. A stress radiograph may be performed with ~5kg weights in the patients hands to better reveal joint instability

  • Axial View - useful for differentiating type III and type IV injuries

    • Axillary Lateral - if posterior Dislocation is suspected

Magnetic Resonance Imaging (MRI)- while typically not the first line of imaging for the Acromioclavicular Joint, MRIs are the gold standard for soft-tissue evaluation. This includes injury to the joints static and dynamic stabilisers, fibrocartilaginous disc or concomitant injury to structures such as the Glenoid Labrum or Rotator Cuff . MRIs can be used to characterise the degree of arthrosis assocaited with conditions such as Osteoarthritis or Septic Arthritis, although caution must be taken to link the patients history and physical examination with findings as ~82% of those with Acromioclavicular arthritis on an MRI are asymptomatic (SOURCE-18+28). Effusion and capsular swelling with soft-tissue or marrow edema may be visualised (SOURCE-18). On an MRI, reactive Bone edema may be a more reliable predictor of symptomatic Acromioclavicular Joint pathology than degenerative changes (SOURCE-28).

Computed Tomography (CT Scan)- while CT scans provide better visualisation of osseous compromise such as Bone erosion or distal Clavicle Fracture s, it does not appear to provide added value over radiographs for the classification of Acromioclavicular Joint injury (SOURCE-18).

Treatment

In lieu of specifc protocols, treatment of Acromioclavicular Joint pathology is generally determined by extent (or type) or injury and the patients circumstances (age, activity level, etc). There is general clinical consensus that conservative management is suitable for lower grade injuries (types I and II) and surgery for higher grade injuries (types IV, V and VI); while the ideal approach for moderate (type III) injury remains contended (SOURCE-8+18+19+20+23+30). For these uncertain type III injuries conservative management is usually attempted for a period of 3-6 months; however, in the presence of persistent instability, an overriding Clavicle or Scapular Dyskinesis prior surgery may be indicated (SOURCE-18+20+23). Irrespective of the Acromioclavicular Joint pathology or the (non)operative approach utilised, treatment is often divided into four familar stages, although the times between these stages may be more context specific:

  • Pain Mitigation - to limit stress on the joints ligaments, immobilisation through the use of a sling is recommended for the initial ~3-10 days if managed conservatively and up to 4 weeks postoperatively (SOURCE-16+20+23+30). Other pain and Inflammation suppressing strategies include rest, thermal compression, oral analgensics and the modification of activities to avoid provocative movements such as repeitive overhead or cross-body (horizontal GH Joint - Adduction ) motions (SOURCE-23+28). With time-frames varying between conservative and postoperative management, patients are often able to tolerate restricted passive shoulder motions and other highly basic exercises within the immobilisation period with the hopes of further reducing pain, inflammation and morbidity (SOURCE-20+30). When these strategies are not sufficient intra-articular corticosteroid injections may be indicated with the possible addition of a local anesthetic agent to confirm the joint is the source of the Pain (SOURCE-18)

  • Range of Motion - once the bulk of Inflammation and Pain has subsided, rudimentary range of motion exercises may be commenced. These should begin as the initial phase Stretching and Strength ening technqiues discussed below in a highly controlled and progressive maner. Typically this phase includes passive and acitve-assisted shoulder or shoulder-adjacent motions and isometric exercises for Scapula stability (SOURCE-23+28+30). Once motion that reflects that of the asymptomatic side, progression to formal Strength development may be pursued (SOURCE-8)

  • Strength - once Range of Motion is predominately restored and Pain -free exercises may be progressed by both range and load to begin challenging and enhacing the capacity of the Muscle . Intuitively, this should begin with simple low load movements such as those described in the initial phase and progressed as tolerated by the patient to those described in the mid-phase

  • Return to Functional Capacity - the last phase in anticipation of a return to sport or full function should be context specific. While basic Strength development may be continued, training intensity and volume should increasingly reflect the demands of the patient, emphasising neuromuscular control or relevant functional patterns (SOURCE-20+23)

Stretching

On an incremental progression of intensity and complexity, Stretching forms an integral part of Acromioclavicular Joint rehabilitation (SOURCE-28). Initially certain shoulder movements are likely provocative and should be approached with caution, including (cross-body) horizontal GH Joint - Adduction , end-range GH Joint - Flexion and GH Joint - Internal Rotation with hand behind back ( Lift-Off Test ) (SOURCE-23). Stretching may be particularly relevant for severe injuries as they are likely accompanied by a longer period of immobilsation (SOURCE-23).

Initial Phase - using predominately passive or active-assisted exercises to avoid excessive stress on the recovering ligaments or address relevant neighbouring structures such as the Scapulothoracic Joint , Glenohumeral Joint or Thoracic Spine (SOURCE-23):

Mid-Phase - full Pain -free Range of Motion should be pursued:

Late Phase - with Range of Motion restored, kinetic-chains under greater loads ( Mobility ) are emphasised:

Strengthening

While time-frames between pathologies, treatment approach and the individual, the relevance of Strength training and its progression from rudimentary to sophisticated exercise remains constant (SOURCE-11+23+28). Emphasis should be placed on improving the capacity of prime movers such as the Pectoralis Minor , Trapezius and Deltoid and coordination of the periscapular and Rotator Cuff Muscles (SOURCE-23+28):

Initial Phase - using predominately passive or active-assisted exercises to avoid excessive stress on the recovering, often immobilised, ligaments and introducing isometrics for the stabilising musculature:

Mid-Phase - as Range of Motion is Pain -free and resembling that of the asymptomatic side, Strength development becomes the primary focus with additional areas of focus such as the Deltoid , Trapezius , Pectoralis Minor and Serratus Anterior :

Late Phase - exercises in this phase should increasingly reflect the demands of the patient or their sport. This includes those that emphasise relevant kinetic chains, plyometrics and advanced strength exercises (SOURCE-23). For exercises with high overhead range, caution should be taken with the lockout position as to not excessively stress the recovering joint (SOURCE-23). A full recovery should be anticipated within roughly 1-3 months depending on the severity of injury and whether it was managed operatively (SOURCE-11+23):

Myofascial Release

The Myofascial Release of the following Muscles or Fascia l structures may be relevant in Acromioclavicular Joint Pain or dysfunction:

Muscle

Fascia

Mobilisation

Given the association of most Acromioclavicular Joint pathology with instability, direct Mobilisations are often more relevant in the treatment of related pathologies of adjacent joints, such as Scapular Dyskinesis or of the Sternoclavicular Joint . Treatment of Acromioclavicular Pain or dysfunction may benefit from Mobilisations of The Shoulder Girdle , Thoracic Spine or in the case of suspected Radiculopathy , Cervical Spine .

Joint Play - passive accessory movements performed without active movement

Mobilisation with Movement - mobilisations applied with an active movement

Closed Reduction

A closed reduction or “relocation” can be performed by a practitioner with the following technique (SOURCE-8):

  • One hand stabilises the Clavicle

  • Other hand produces a superiorly directed axial force through the Humerus from The Elbow

Surgery

Acromioclavicular injuries that also involve neurovascular structures or penetrate the skin are absolute indicators surgery (SOURCE-8). Other factors such as floating shoulders, fragments lodged in the Trapezius or complete rupture of the joints stabilisers may indicate surgery (SOURCE-8). ARockwood Classification Systemis a widely-used approach for determining the severity of Acromioclavicular Joint injuries which guides treatment direction. Low grade injuries (Type I and Type II) are conservatively managed, higher grades (Types IV, V and VI) typically require surgery while the intermediate Type III injuries remain ambiguous (SOURCE-9+10). While there is no single “gold standard” procedure there has been a perspective shift from traditional simple (Screw or Hook Plate) fixation techniques to more anatomic reconstructions (suture-button system or biological graft) which are more congruent or reflective of the joints natural articulation and biomechanics (SOURCE-9+11):

  • Coracoclavicular (CC) Screw Fixation - one of the oldest techniques that involves open reduction of the Acromioclavicular Joint and insertion of a screw from the Distal Clavicle into the Coracoid Process of Scapula . A decrease in popularity is attributed to higher rates of hardware failure and screw removal

  • Hook Plate Fixation - a plate is fixed to the superior surface of the Clavicle with a hook that engages the inferior surface of the Acromion which affords a stable reduction. The hook may lead to complications that perpetuate or cause Subacromial Impingement or lead to erosion of the Acromion

  • Endobutton Coracoclavicular Fixation - a modern and typically arthroscopic approach which utilises a synthetic suture-button system to restore the native Coracoclavicular Ligament s. Either one button is used to replace the entire ligament complex or two that replace the Conoid Ligament and Trapezoid Ligaments individually

  • Ligament Reconstruction with Biological Grafts - autografts and allografts used to anatomically reconstruct the Coracoclavicular Ligament and Acromioclavicular Ligaments

General postoperative recommendations are congruent with those discussed above for conservative managment, albeit with a more cautious progression. In instances where concomitant procedures were performed, rehabilitation is typically guided by the other procedure (SOURCE-16). Generally at 2-3 weeks postoperatively the patient may commence passive, active-assisted and select isometric movements with the main restriction being arm elevation beyond 90º (SOURCE-11+16)

Other

Other treatment modalities used to address Pain or dysfunction in the Acromioclavicular Joint include (SOURCE-18+23+28+31):

  • Nonsteroidal Anti-Inflammatory Drugs (NSAIDs)- used to relieve Pain and Inflammation , particularly in the initial phase of injury

  • Corticosteroid Injections- when other conservative management strategies are not sufficient intra-articular corticosteroid injections may be indicated with the possible addition of a local anesthetic agent to confirm the joint is the source of the Pain

  • Cryotherapy- used to relieve Pain and Inflammation for short-term improvements in function

  • Kinesiology Tape- taping of the joint can be used to relieve Pain

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