Disease is a general term covering a range of conditions. This can be due to trauma, such as a dislocation of the acromioclavicular joint, or a degenerative disease, such as osteoarthritis.  Acromioclavicular joint dislocation is a traumatic dislocation of a joint in which The collarbone occurs relative to the shoulder. 
Clinically Relevant Anatomy
The acromioclavicular joint is a moving joint with a fibrocartilaginous meniscus that connects the clavicle to the acromion. It has an intra-articular synovial and articular cartilage interface  and is characterized by various inclinations of the sagittal plane and coronal and disc. 2 types of discs have been observed; intact discs (very rare) and meniscus-like discs. . The acromioclavicular joint is surrounded by a joint capsule and is composed of superior/inferior capsular ligaments and coracoclavicular ligaments (trapezoidal and Cone) is also an important structure for joint stability. 
The acromioclavicular (AC) and coracoclavicular (CC) ligaments are part of the static stabilizer of the joint. The AC ligaments control horizontal stability in the anterior-posterior plane, while the CC ligaments are used to control vertical stability. the conical portion of this ligament The trapezoidal portion attaches posteriorly and medially to the clavicle, and the trapezoidal portion attaches anteriorly and laterally. The trapezius and deltoids also provide dynamic stability of the AC joint. 
AC joint injuries account for approximately 10% of acute shoulder girdle injuries, and AC joint separations account for 40% of shoulder girdle injuries in athletes. Usually the injury occurs when an outstretched hand or elbow hits the shoulder directly during a fall or falls to the point of the shoulder. 
Figure 2 illustrates common injury mechanisms: (A) direct force on the shoulder point (B) indirect force on the AC joint can also cause injury. For example, a fall on the elbow drives the humerus proximally to disrupt the acromioclavicular joint. In this case, force refers only to AC ligament instead of coracoclavicular ligament. 
This injury is commonly seen in hockey and football players, but has also been seen in alpine skiing, snowboarding, football, bicycle, and motor vehicle accidents. 
With AC joint injuries, the pain usually radiates to the neck and deltoid. The AC joint may also become swollen and the upper extremity is often adducted and the acromion depressed, which may cause the clavicle to elevate. 
A 3-level classification was described by Allman et al., which was extended by Rockwood and Green to a 6-level classification model (called the Rockwood scale). This classification of AC joint injuries helps determine appropriate treatment and helps avoid Identify patterns of injury. 
Rockwood damage rating. (AC: Acromioclavicular CC Coracoclavicular) grades describe observation/testing of AC ligament sprains. AC and CC ligaments intact No clavicle instability detected on stress test IIAC ligament rupture CC ligaments intact. usually described as Subluxation. The clavicle is unstable for direct stress testing. The IIIAC and CC ligaments are completely destroyed, while the deltoid fascia is not significantly disrupted. This is often described as a dislocation. Deformity manifested by elevated clavicle (depressed acromion) Instability in both vertical and horizontal planes IV Posterior deformity with posterior displacement of distal clavicle into trapezius muscle. V More severe grade III form. The AC and CC ligaments are completely ruptured and the deltoid fascia is ruptured. Pseudolateral clavicle The elevation of the scapula shifts downward. VI Subacromial or subcoracoid inferior displacement of the distal clavicle Major trauma is usually accompanied by other major injuries.
Due to the higher intraobserver and interobserver reliability, numerical measurements are recommended over purely visual diagnosis. 
- Most dislocations are at the glenohumeral joint, with 90% of them occurring anteriorly, which can lead to concomitant lesions such as Hill sachs injuries or brachial plexus injuries. 
- AC joint pain due to 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 
- Acromioclavicular joint dislocations are usually diagnosed radiographically. Patients with type I injuries can be problematic because there are no obvious abnormalities on x-rays. Therefore, diagnosis depends on the mechanism of injury and tenderness of the AC joint. 
- Resisted AC Joint Extension Test
- DASH: Arm Shoulder and Hand Disability Questionnaire. 
- Simple Shoulder Test Questionnaire: Aims to assess shoulder dysfunction scored from 12 questions: 2 on pain-related function, 7 on function/strength, and 3 on range of motion 
- Shoulder Pain and Disability Index (SPADI): The primary outcome measure is patient perception of pain and disability. It consists of 2 subscales of pain and disability which are combined to produce a total score ranging from 0 (no pain or functional difficulty) to 100 (the highest level pain and dysfunction). SPADI is reliable, effective and responsive for musculoskeletal neurogenic or unexplained shoulder pain. 
- American Shoulder and Elbow Surgeons (ASES): This measures functional limitation and pain in patients with musculoskeletal shoulder disorders. Functional scores are calculated from 10 function-related questions using a 4-point scale. 
- AC Joint Palpation for Tenderness
- O’Brien’s test: Examination using the O’Brien’s test tightens the posterior joint capsule and translates the humeral head posteriorly, putting pressure on the labrum, causing pain and weakness.
- Paxinos sign: provocative test for acromioclavicular joint injury  . Walton et al found the Paxinos test to be an excellent clinical diagnostic tool and bone scan to be the most reliable imaging modality for diagnosing AC joint pathology. When both tests are positive, High confidence in pathological diagnosis of AC joints .
- Test of Stenvers 4: Clavicular Roll
- Resisted AC Joint Extension Test
The mechanism of injury and palpation history of the AC joint helps to distinguish between Type I and Type II injuries. Slight deformity of the AC joint indicates a type II injury. In type I injuries, swelling is usually accompanied by pain when the arm is abducted, whereas in type II injuries Pain usually occurs with all movements of the arm. A pronounced step deformity of the AC joint indicates a type III injury, and the patient usually supports the injured arm as close to his body as possible. 
Treatment for an AC joint injury will vary based on its severity.
Nonoperative treatment is recommended for type I and type II AC separations, but for type III this remains much debated because of the high likelihood of early intra-articular degeneration. However, surgical intervention may be an option as this may yield better functional outcomes in some cases Especially in cases where the patient is younger, highly active, or has a type III injury that does not respond to conservative treatment. For types IV and V, surgical repair is strongly recommended.
There are several surgical methods, but the 4 most common are:
- AC joint fixation using hook-plates
- coracoacromial ligament transfer
- coracoclavicular interval fixation
- Coracoclavicular ligament reconstruction
Physical Therapy Management
Conservative – Types I and II
Initial treatment should follow the POLICE protocol, including preservation of optimal load ice compression elevation and referral within the first 48 hours. A sling should be used to immobilize the shoulder and keep it in an elevated position while resting. recording to help support Joints are also useful.
A sling may be used in place until the pain subsides. Return to normal activities typically takes 2–4 weeks for Type I injuries, 4–6 weeks for Type II injuries, and 6–12 weeks for Type III injuries . Intra-articular steroid injections may be required for patients whose symptoms do not improve within this range 
However, evidence on rehabilitation programs is lacking. Best practice guidelines were developed by Reid et al. following a systematic review of current practice 
Range of Motion (ROM): Passive Active – Assisted Active
- Glenohumeral Joint (GHJ): Internal Rotation External Rotation Flexion to Tolerance: Towel Slide Oscillating Motion
- Scapula: stretch forward, retract backward, lift up and sink
- Active Assisted Exercises Using 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 of GHJ: Sleeper Stretch
Isometric exercises: should be multi-angle submaximal and subpainful
Closed Kinetic Chain: (no weight)
- Hands are supported in different planes and elevation levels, controlling the position of the scapula and progressing to 90°
- Elbow Support Internal/External Rotation
- wall slides, scapula clock
- push-ups on wall
Avoid aggravating injuries: Examples of exercises are bench presses, push-ups, shoulder presses, or dips. Proximal stability must be achieved prior to strength.
Range of Motion: Restores the full range of motion of the GHJ (including horizontal adduction) IR/ER during 90° abduction of the GHJ and extension of the joint capsule.
Closed Kinetic Chain: Increase the load from the previous closed kinetic chain exercise. Add active arm elevation and rotation.
Axial Load Active ROM (Transition from Closed Kinetic Chain to Open Kinetic Chain (OKC)):
- Wall Slides with Trunk and Lower Body Workouts
- wall slides in the scapular plane
- Trunk and hip extension (scapular retraction), such as low-row exercises
- Trunk and hip flexion (scapular extension), eg fist
- Bilateral and unilateral pull torso rotations, such as uppercuts
- Compound Deltoid Movements: Cable Shrug Abduction Exercises at Various Angles
Plyometrics (Dynamic Stretching and Shortening): Medicine ball throws and catch tube plyometrics. Sport-specific exercise: Overhead athletes use both hands to throw side to side overhead.
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
Types V and VI are considered to require surgical repair, and physical therapy may follow various postoperative options.
Studies comparing the outcomes of nonoperative and surgical treatment of type III AC dissociation have shown no substantial benefit from surgical intervention. Bannister et al concluded that conservative treatment of type III injuries is more likely to restore total shoulder kinematics Fast and with few complications.  Conservative treatment should be considered as first-line treatment for type III dissociation 
For types IV and V injuries, there is no evidence-based literature recommending specific treatments for these injuries. Surgery is the treatment of choice, but there have been reports of successful conversion of type IV to type II using manual reduction. 
Goals post surgery
- Control pain and swelling
- Protect the AC joint repair
- Protect wound healing
- Begin early shoulder motion
Post surgical management
- Apply cold compresses to your shoulder after surgery to reduce pain and swelling.
- Remove the strap several times a day and gently swing your arms: lean forward and passively swing your arms.
- Apply cold compresses to the shoulder for 20 minutes at a time as needed to reduce pain and swelling.
- Remove the strap several times a day: move the elbows and hands. Bend over for 3 to 5 minutes of pendulum motion every 1 to 2 hours.
- Wash the underside of the operated arm, bend down, and let the arm passively leave the body. It is safe to wash your underarms in this position. This is the same position as the pendulum moves.
- Protocols regarding active movement and sling use will vary depending on the surgeon and the procedure being performed. Some will prescribe no active arm movement for up to 6 weeks and require the use of a sling. Others may allow use of the sling as needed and immediate active movement, such as up to 90 degrees on the first movement Two weeks slowly progressed from there.
Postoperative rehabilitation follows similar guidelines as for Type I and Type II injuries. Treatment initially consists of ROM exercises followed by progressive strengthening. Rehabilitation is required to achieve adequate strength and mobility to avoid persistent AC Joint pain and instability.  
- ↑ Codsi JM. The painful shoulder: when to inject and when to refer. Cleveland clinic journal of medicine 2007; 74(7): 473-482. (level of evidence 4)
- ↑ Heijmans E, Eekhof J; Neven AK. Acromioclaviculaire luxatie, huisarts & wetenschap, november 2010(level of evidence 5)
- ↑ Saccomanno MF. Acromioclavicular joint instability: anatomy, biomechanics and evaluation. Joints 2014; 2(2): 87–92.
- ↑ De Palma AF. Surgical anatomy of the acromioclavicular and sternoclavicular joints. Surg Clin North Am. 1963;43:1541–1550.
- ↑ Salter EG, Jr, Nasca RJ, Shelley BS. Anatomical observations on the acromioclavicular joint in supporting ligaments. Am J Sports Med 1987;15(3):199-206.
- ↑ Jump up to:6.0 6.1 6.2 6.3 Magee DJ, Zachazewski JE, Quillen WS. Pathology and Intervention in Musculoskeletal Rehabilitation.fckLRElsevier Health Sciences, 2008.
- ↑ Suezie K, Blank A, Strauss E. Management of Type 3 Acromioclavicular Joint Dislocations Current Controversies. Bulletin of the Hospital for Joint Diseases 2014; 72(1): 5360.
- ↑ Beim GM. Acromioclavicular joint injuries. Journal of Athletic Training 2000;35(3):261-267.
- ↑ Johansen JA, Grutter PW, McFarland EG, Petersen SA. Acromioclavicular joint injuries: indications for treatment and treatment options. J Shoulder Elbow Surg 2011;20:70-82.
- ↑ Culp LB, Romani WA. Physical Therapist Examination, Evaluation, and Intervention Following the Surgical Reconstruction of a Grade III Acromioclavicular Joint Separation. Journal of the American physical therapy association 2006; 86:857-869.
- ↑ Jump up to:11.0 11.1 Micheli LJ. Encyclopedia of Sports Medicine. London: SAGE Publications, 2010.
- ↑ Jump up to:12.0 12.1 12.2 12.3 12.4 Reid D, Polson K, Johnson L, Acromioclavicular Joint Separations Grades I–III A Review of the Literature and Development of Best Practice Guidelines. Sports Med. 2012; 42(8): 681-696.
- ↑ Schneider MM, Balke M, Koenen P, Fröhlich M, Wafaisade A, Bouillon B, Banerjee M. Inter- and intraobserver reliability of the Rockwood classification in acute acromioclavicular joint dislocations. Knee Surg Sports Traumatol Arthrosc. 2016; 24(7): 2192-6.
- ↑ Nepola VJ, Newhouse EK, Recurrent shoulder dislocation. The iowa orthopaedic journal 1993; 13: 97-106
- ↑ Robb AJ, Howitt S, Conservative management of a type III acromioclavicular separation: a case report and 10-year follow-up. Journal of Chiropractic Medicine 2011; 10: 261–271.
- ↑ Jump up to:16.0 16.1 16.2 16.3 16.4 16.5 16.6 Fraser-Moodie JA, Shortt NL, Robinson CM. Injuries to the acromioclavicular joint. J Bone Joint Surg. 2008 ;90-B: 697-707.
- ↑ 4. Johansen JA, Grutter PW, McFarland EG, Petersen SA. Acromioclavicular joint injuries: indications for treatment and treatment options. J Shoulder Elbow Surg. 2011;20 p.S70-82
- ↑ Jump up to:18.0 18.1 Harris KD, Deyle GD, Gill NW, Howes RR. Manual Physical Therapy for Injection-Confirmed Nonacute Acromioclavicular Joint Pain. Journal of orthopaedic & sports physical therapy 2012; 42(2): 66-80.
- ↑ Jump up to:19.0 19.1 Walton J, Mahajan S, Paxinos A, Marshall J, Bryant C, Shnier R, Quinn R, Murell GAC. Diagnostic Values of Tests for Acromioclavicular Joint Pain. The Journal Of Bone & Joint Surgery 2004; 86-A (4): 807-812.
- ↑ Culp LB, Romani W. Physical Therapist Examination, Evaluation, and Intervention Following the Surgical Reconstruction of a Grade III Acromioclavicular Joint Separation. Journal of the American physical therapy association 2006; 86:857-869.
- ↑ nabil ebraheimExamination Of The AC Joint – Everything You Need To Know – Dr. Nabil Ebraheim. Available from https://www.youtube.com/watch?v=daPnkXo03yM&t=1s
- ↑ Johansen JA, Grutter PW, McFarland EG, Petersen SA. Acromioclavicular joint injuries: indications for treatment and treatment options. J Shoulder Elbow Surg. 2011;20: S70-82
- ↑ Jump up to:23.0 23.1 Hootman JM. Acromioclavicular Dislocation: Conservative or Surgical Therapy. Athl Train. 2004; 39(1):10–11.
- ↑ Physio Fitness | Physio REHAB | Tim Keeley”Weight-lifter’s shoulder” pain from an unstable AC joint | Feat. Tim Keeley | No. 27 | Physio REHAB. Available fromhttps://www.youtube.com/watch?v=aLj–YqCXhw&t=2s
- ↑ Bannister GC, Wallace WA, Stableforth PG, Hutson MA. The management of acute acromioclavicular dislocation. A randomised prospective controlled trial. Bone Joint Surg Br. 1989; 71(5): 848-850.
- ↑ Nissen CW, Chatterjee A. Type III acromioclavicular separation: results of a recent survey on its management. Am J Orthop (Belle Mead NJ). 2007 Feb. 36(2):89-93.
- ↑ Johansen JA, Grutter PW, McFarland EG, Petersen SA. Acromioclavicular joint injuries: indications for treatment and treatment options. J Shoulder Elbow Surg. 2011;20 p.S70-82
- ↑ Johansen JA, Grutter PW, McFarland EG, Petersen SA. Acromioclavicular joint injuries: indications for treatment and treatment options. J Shoulder Elbow Surg. 2011; 20: S70-82
- ↑ Glick JM, Milburn LJ, Haggerty JF, Nishimoto D. Dislocated acromioclavicular joint: follow-up study of 35 unreduced acromioclavicular dislocations. Am J Sports Med 1977; 5: 264-70.
- ↑ KT Tape. KT Tape: AC Joint. Available from: https://www.youtube.com/watch?v=DJEhxOkg8Pg [last accessed 28/3/15]