What is a separated shoulder (AC Joint separation)?

Dr. Timothy Hamby of Tri-State Orthopaedics helps us understand Shoulder Separatation (aka AC joint separation)

What is a Separated Shoulder?

Separated shoulder, is also known as AC joint separation.  This injury is a result of falling directly on the shoulder or a direct blow to the shoulder.   This injury occurs in 9-12% of shoulder injuries. Here is all you need to know about recognizing AC joint separation and its treatment.  

Understanding the anatomy.

Three bones form the shoulder joint: the humerus (upper arm bone), scapula (shoulder blade) and clavicle (collarbone).  The AC joint, which stands for acromioclavicular joint, is where the clavicle meets the highest portion of the scapula, known as the acromion, and is held together by ligaments known as the acromioclavicalar (AC) ligament and coracoclavicular (CC) ligament.

Who gets AC joint separation?

This most often occurs in men in their 20’s who participate in contact sports like football, hockey and wrestling.  However, it can occur in anyone with a traumatic injury to the shoulder.

What causes AC joint separation?

AC separations often occur from falling directly onto the shoulder.  The force of falling on the shoulder injures the ligaments that connect the clavicle and acromion, by either a sprain (stretch) of the ligament or tear.  The force of the fall determines the severity of the injury. When the ligaments torn the clavicle separates from the acromion, the clavicle will then elevate and the acromion will then drop due to the weight of the arm.  This results in a bump over the top of the shoulder.

AC separations can also occur from indirect injury like falling onto outstretched arm or falling onto your elbow pushing the humeral head into the acromion injuring the joint

What are the symptoms of AC joint separation?

Usually there is an injury resulting in pain in the shoulder and then one would notice a bump over the top of the shoulder.  There are grades to separation ranging from 1-6, with increasing in grade you can expect increase in pain and deformity. Patients will also experience pain and popping with overhead range of motion and cross body range of motion and might even experience lack of range of motion in these directions.  

What are the grades of AC joint separation?

Grade I or II/ Mild separation:  sprain of the AC ligament with no movement of the clavicle from the acromion.  This is the most common AC joint separation, occurring twice as often then higher grades.   

Grade III-IV/ Moderate separation: tearing of the AC ligament with sprains of the CC ligament.  There is significant noticeable elevation of the clavicle at this point.

Grade V-VI/ severe separation: complete tears of both the AC ligament and CC ligament resulting in obvious elevation of clavicle.  

How do you diagnosis of AC joint separation?

When seeing an orthopedic surgeon we can diagnose AC joint separation with history and physical exam.  History will most likely include direct injury to the shoulder. Most patients on physical exam will be tender to palpation over the AC joint with a possible elevated clavicle.  X-ray is used to confirm diagnosis and determine the grade of separation, which will also help rule out any other possible injury to the shoulder like fracture of the humerus, scapula or clavicle.  There is a specific x- ray technique used to for AC joint injury and normally both AC joints will be imaged for comparison.

Treatment of AC joint separation.

Treatment depends on your grade or severity of separation.  

Grade I and II:   This is a mild injury so treatment is usually conservative and patients recover quickly.  You will start with rest, ice, NSAIDs and possible sling for comfort. Physical therapy is started for range of motion and strengthening fairly quickly.  

Grade III:   This is a moderate injury to the AC joint.  Treatment for this is more controversial. Some experts recommend non-operative treatment with rest, ice, sling and NSAIDs.  If your pain persists or deformity is concerning surgery could be considered. Other experts recommend surgery for athletes or laborers for Grade III separations.  The surgery is discussed further below. Grade III separation takes a total of 6-12 weeks to fully heal before returning to sport or heavy overhead work.

Grade IV, V, VI: This is the severe injury to the AC joint.  These usually require surgical treatment, either open or arthroscopic procedures.    Some chronic injuries require use of a graft to reconstruct the ligaments that are torn.  The purpose of surgery is to realign the clavicle to the acromion. Surgical patients are placed in a sling for six weeks with no overhead activity.   After six weeks the sling is removed and patients start physical therapy for range of motion and strengthening. Total healing time for this severity of injury can be up to 6 months.  

If you or a loved one is experiencing shoulder pain, contact Dr. Timothy Hamby at Tri-state Orthopaedics.  Contact information is below along with a link to schedule an appointment.

Tri-State Orthopaedics Scheduling:  812.477.1558

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