What is shoulder (acromioclavicular) separation?
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Trauma to the acromioclavicular (AC) joint is the most common shoulder injury. Because the tissue injury is often sufficient to cause joint disruption and “separation” of the acromion (front of the shoulder blade) from the clavicle (collarbone), it is also known as, “AC separation” or “separated shoulder.” AC separation is a sprain (partial or complete tear) of the acromioclavicular joint, which is the connection between the end of the clavicle and the acromion. Normal stability of this joint is provided by a thickening of the capsule around the AC joint plane and two discrete ligaments from the tip of the coracoid to the undersurface of the clavicle, called the coracoclavicular (CC) ligaments. (Figure 1)
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How does a separated shoulder occur?
AC joint injury occurs due to direct trauma to the point of the shoulder, usually from landing directly on it. It is commonly seen in collision sports such as football, hockey, rugby or lacrosse. Skiing is another common cause for this injury. The traumatic load applies an inferiorly directed force on the acromion relative to the clavicle. The degree of injury depends on the severity of this force, ranging from mild injury limited to the AC joint capsule to more severe injury leading to sprain and ultimate disruption of the supporting CC ligaments.
- Impact or direct fall onto the point of the shoulder (for example, from a fall off a bike)
- Less commonly, injury can occur with a fall onto the outstretched hand or the elbow
Increased risk of injury occurs with:
- Sports requiring contact or collision
- Inadequate protective equipment in contact sports such as football/hockey
What are the symptoms of a separated shoulder?
- Acute pain with localized tenderness directly over the AC joint
- Swelling and/or deformity, often with a “bump” on the top of the shoulder. This “bump” represents the end of the clavicle, which is “sprung” and rests above its normal position.
- Bruising may be present around the site of injury within 48 hours
- An abrasion may be present over the top of the shoulder (the site’s direct impact)
- Pain and weakness may be present with overhead activities, when reaching across the body (e.g., to wash under opposite arm), or reaching behind (e.g., to reach wallet or scratch back)
How is a separated shoulder diagnosed?
- In the most commonly used classification scheme, there are three types of sprains, based on the degree of injury to the AC joint and the CC ligaments.
- In a Type I, there is a sprain (partial tearing) of the AC joint, but no injury to the CC ligaments.
- In a Type II, there is complete disruption of the AC joint and a partial sprain of the CC ligaments.
- In a Type III AC Separation, there is complete disruption of the AC joint and of the CC ligaments. In essence, a Type III AC separation means complete disruption of the normal attachments between the acromion and clavicle.
- This classification is easy to establish based on physical and X-ray examination, and is clinically useful in determining prognosis and treatment. More complex classification schemes add three more types of AC joint injury, but these other types are much less common.
Are there any special tests?
- No special tests are usually necessary.
- Occasionally, a Type III sprain will masquerade as a Type I or II and appear minimally or non-displaced on initial x-rays. For this reason, some clinicians have advocated obtaining stress views to ensure Type III separations are not missed.
- Stress views are obtained by securing weights (5 to 10 lbs.) to the patients' wrists, and obtaining X-rays of both AC joints (on the same film if possible). In a Type III AC separation, this additional stress will cause the acromion to be displaced inferiorly, thereby “opening up” the AC joint.
- In practice however, this test is rarely necessary for two reasons. First, most grade III separations are evident without requiring stress views. Second, making the distinction between Grades II and III is somewhat irrelevant since treatment, at least until relatively recently, has usually been the same.
How is shoulder separation treated?
- Initial treatment consists of medication and ice to relieve pain
- A sling is usually prescribed initially for comfort.
- Pain medication, in the form of either acetaminophen or a non-steroidal anti-inflammatory drug (NSAID) (e.g., ibuprofen, naproxen sodium, or prescription form) may be of value early on in the treatment. Take these as directed by your physician. Discontinue the medication if you experience any stomach upset or other reaction. You should not take any NSAID if there is any chance of pregnancy.
- Modifying daily activities may be necessary during early recovery, meaning avoiding activities that are “provocative,” i.e., painful. Such activities could include lifting or carrying anything with that arm, or overhead use.
- There are two definitive treatment options for management of AC joint injuries – non-operative and operative.
Non-operative treatment is indicated for most patients, who are able to successfully resume all pre-injury activities.
Traditional treatment has been predominantly non-operative, as operative treatments have historically not been proven superior to “benign neglect.” However, recent evolution in surgical techniques has questioned the traditional wisdom of leaving these injuries alone, especially because the natural history is not necessarily forgiving for all patients, particularly those with Type III injuries.
Outcome with non-operative treatment is influenced by the degree of injury.
- Type I AC separation, or mild sprain, usually begins improving within first week, with progressive return of normal function and strength. Specifically, Type I injuries are usually mild and will permit active motion within a few days. Football players with this injury will probably be able to return in time for the next game, though they may be sore. The risk of developing late degenerative changes is about 5 percent.
- Type II AC separations are treated identically to Type I injuries, with recognition that risk of later degenerative joint changes is slightly higher in Type II’s, perhaps 10 percent. Time out of competition is usually larger for these moderate sprains, and may require several weeks for substantial improvement. This type of separation has a higher incidence of longer-term pain, with those using their arms for heavy lifting, overhead work, or athletic endeavors having an approximately 10 percent risk of symptoms.
- Type III AC separations are the injuries that are typically thought of when describing a “separation,” as there is noticeable prominence of the end of the clavicle and AC joint deformity. Even these significantly injured joints however, statistically do well, with overall improvement to the point of being symptom-free in about 85 percent of patients.
- Type III injuries are treated non-operatively in most cases. There is no role for use of a special bandage or splint in grade III’s, because there is no device that will maintain the joint in a “reduced” position. For this reason, the patient is treated for comfort only. A sling is usually just as effective as a figure-of-eight bandage.
- Type III sprains usually lead to a longer period of disability, but eventually most people are able to return to their previous level of activity. Problems associated with Type III injuries include cosmetic deformity, risk of late degenerative arthritis and/or dysfunction, and easy fatigue of the shoulder. The “bump” will not spontaneously resolve and patients should be forewarned of this fact. In muscular individuals, deformity may not be noticeable; conversely, in thin patients, prominence of the clavicle is often evident. Nevertheless, most patients learn to tolerate the appearance, and if they can do so, the likelihood of pain and/or dysfunction is small, estimated at approximately 15 percent.
Possible complications of non-operative treatment include:
- Weakness and fatigue of the arm or shoulder
- Pain and degenerative changes at the AC joint
- Prolonged healing time may occur if activities are resumed prematurely. The timing of return-to-activity should include your personal physician and/or trainer/therapist.
- Prolonged disability can occur in a small number of patients (most commonly Type III’s)
Operative treatment is usually reserved for the small number of patients with Type III (or higher degree) AC separations who are intolerant of the cosmetic appearance, cannot afford the “wait and see” approach of non-operative treatment, or have not improved after a reasonable period (several months) of non-operative treatment. Examples of patients sometimes considered surgical candidates include athletes and overhead laborers whose demands may preclude a successful return to activity. Symptoms in this group include pain, easy fatigability, or both.
Recent technical advances in AC joint fixation have led to an increased frequency of surgical treatment for Type III separations. Such surgery can be accomplished through an arthroscopic and small-open incision approach, anatomically restoring the joint. Such early intervention (within the first few weeks following injury), may take advantage of the “biologic mileau” of the injured shoulder, permitting anatomic healing, and leading to better long-term outcomes. Preliminary results of acutely repaired AC injuries are promising but only longer follow-up and randomized comparison trials will confirm the early promise of this approach.
“Weaver-Dunn” technique
In those patients who remain symptomatic or find themselves functionally impaired following non-operative treatment, surgical reconstruction can lead to restoration of normal anatomy and function. Historically, a “Weaver-Dunn” technique (named for the initial authors) was advocated, transferring a local ligament (the Coraco-Acromial ligament) to substitute for the previous CC ligaments. However, recent studies have shown the tissue substitute is relatively weak compared to the original CC ligaments. In addition, this tissue transfer is at a biomechanical disadvantage as well, due to non-anatomic orientation of the transferred ligament. This historic standard is unable to replicate normal anatomy and for this reason has fallen out of favor.
Currently, anatomic restoration of the joint is achieved by recreating the CC ligaments using tissue graft. In the most common method, an open incision is used to expose the sites of origin (the coracoid) and insertion (clavicle) of the CC ligaments, and a graft (usually an autograft {from the same person} hamstring tendon) is fixed between these two sites. Often the reconstruction is “augmented” by additional fixation devices or suture material.
Possible complications of operative treatment include:
- Failure to restore normal anatomic position
- Failure to maintain reduction (normal AC joint position)
- Complications not specifically associated with AC joint repair/reconstruction, such as pain, bleeding (uncommon), infection (<1percent), nerve injury (uncommon), stiffness, problems with anesthesia, and inability to return to previous level of pre-injury activity.
When can you return to your sport or activity?
Return to sports and other activities are earlier with non-operative treatment and are based on type of sport and position, arm injured (dominant versus non-dominant) and the type of AC separation (injury severity). Surgical repair or reconstruction, typically require a period of four weeks in a sling, followed by gradual return to activities of daily living. Surgical intervention usually delays full return to athletic activity for approximately four months.
How can shoulder separation be prevented?
- Fundamentally, AC separations occur during participation in contact/collision athletics. In that regard, they cannot really be prevented with the exception of wearing appropriate protective padding/gear.
- Ensure proper protective equipment fit
- Develop proper falling/landing technique with coaching/trainer involvement as necessary
- Taping, protective strapping or padding, or an adhesive bandage may be of value
Additional Resources:
- Painful Conditions of the AC joint (linked PDF file)
- Acromioclavicular and Distal Clavicle Injuries (linked PDF file)
