The acromioclavicular (AC) joint serves as the connection point between the clavicle (collarbone) and the acromion, a specific portion of the scapula (shoulder blade). The AC joint is fairly strong and is held together by ligaments and cartilage that allow overhead arm movements. An AC joint injury most commonly occurs from direct impact to the top of the shoulder, such as a hard hit or fall during sporting activities. The traumatic event can cause patients to experience a mild sprain or a complete separation, both injuries leading to acromioclavicular joint pain. Long Island, Brooklyn, Queens and NYC orthopedic surgeon and shoulder specialist, Dr. Jonathan Ticker strives to return all patients to the activities they enjoy following an injury to the AC joint.

An AC joint injury causes damage to both the cartilage and ligaments that hold the joint together and allow normal joint function. Injuries to the AC joint are graded on a 1-6 scale within the medical field, with increasing numbers reflecting a worsening injury level.

AC joint injury grade levels include:

  • Grade 1- AC joint sprain, X-rays appear normal
  • Grade 2- AC joint advanced sprain, slight widening of joint on X-rays
  • Grade 3- AC joint separation, the clavicle bone is higher than the acromion up to 100% (nearly completely separated)
  • Grade 4- AC joint separation, the clavicle is completely separated posteriorly (backwards)
  • Grade 5- AC joint separation, the clavicle bone is higher than the acromion between 100 to 300% (complete severe separation)
  • Grade 6- AC joint separation, the clavicle is completely separated inferiorly (lower)

Symptoms of an AC Joint Injury

Acromioclavicular joint pain is the hallmark symptom, no matter the severity of the AC joint injury. Patients with a grade 1-2 injury often experience minor swelling, tenderness and mild deformity, while more serious grade injuries (grade 3-6) often cause patients to experience more severe pain, inflammation, swelling, visible deformity and the inability to lift the arm.

Diagnosis of an AC Joint Injury

Dr. Ticker will perform a thorough physical examination, and a series of x-rays in order to diagnose an AC joint injury. The physical examination will determine the level of tenderness directly above the AC joint as Dr. Ticker brings the patient’s arm across the body. An MRI scan may also be performed to evaluate for possible additional bony and soft tissue injuries.

Treatment of an AC Joint Injury


In many cases, an AC joint injury is initially treated by Dr. Ticker with a combination of non-surgical measures. In order to alleviate acromioclavicular joint pain and to promote healing, patients will be instructed to utilize ice, rest the shoulder and take anti-inflammatory (NSAIDs) medications. Over time, patients may be prescribed a physical therapy program to help strengthen the joint and to help regain full function and mobility.


If conservative measures fail to alleviate acromioclavicular joint pain or if the AC joint injury is too severe (commonly grades 4-6), Dr. Ticker may recommend an arthroscopic surgical procedure. A minimally invasive approach is generally performed to stabilize the end of the clavicle in its proper position and to correct the separation of the clavicle and acromion.

For additional resources on acromioclavicular joint pain, or for more information on the treatment of an AC joint injury, please contact the Long Island, Brooklyn, Queens and NYC area orthopedic office of Dr. Jonathan Ticker.