AC Joint Grading System | AC Joint Separation Grading X-Ray

AC Joint Grading System Overview

An acromioclavicular (AC) joint separation is the medical classification for the separation of the collarbone from the shoulder blade. An AC joint separation is a common injury in the active population and typically occurs from a hard fall or direct hit to the AC joint. AC joint separation grading helps physicians properly diagnosis and plan for proper treatment based on the extent of injury. The AC joint grading system includes a scale of six grades, and is determined by the level of separation found in the diagnostic x-ray and MRI. The most common AC separations are grade 1 through grade 3. Dr. Peter Millett specializes in diagnosing and treating AC joint injuries, helping patients return to the athletic activities they love.

AC Joint Separation Grading Scale

During an injury to the AC joint, soft tissues may become torn, leading to a varying amount of damage. An AC joint separation is graded by the extent of damage sustained to the ligaments. An AC joint separation grading scale includes:

Grade 1 – AC joint separation is a mild shoulder separation where the AC ligament is stretched or partly torn.
Grade 2 – AC joint separation is a partial separation of the AC joint where the AC ligament is completely torn but the coracoclavicular (CC) ligaments are intact.
Grade 3 – AC joint separation is a complete separation of the joint where the AC ligament and CC ligaments are completely torn, as well as the joint capsule.
Grades 4, 5 and 6 – AC separations are extremely rare and occur when there is significant posterior movement of the clavicle (collar bone) in relation to the acromion (bony process on the shoulder blade).

What are the symptoms of AC joint separation?

The symptoms of an AC joint separation vary based on the extent of the injury. Treatment treatment options are dependent on the extent of the injury based on the AC joint grading system.

Grade 1 – A grade 1 injury typically causes mild tenderness, bruising and minor pain.
Grade 2 – A grade 2 injury typically causes moderate to severe pain, swelling and a small bump may be present on the top of the shoulder where the clavicle ends.
Grade 3 – A grade 3 AC joint separation injury causes severe pain, swelling, instability and visible deformity.

Have you sustained an AC joint injury and would like information on the severity?

There are two ways to initiate a consultation with Dr. Millett:

You can provide current X-rays and/or MRIs for a clinical case review ($250).

You can schedule an office consultation with Dr. Millett.

Request Case Review or Office Consultation

AC Joint Separation Grading MRI and AC Joint Separation Grading X-Ray

In order to diagnose an AC joint injury and determine the injury level based on the AC joint grading system, Dr. Millett will perform a complete medical review and physical examination. He typically moves and feels the injured joint to get a better understanding of injury and to identify areas of pain and weakness. In many cases, Dr. Millett will perform an AC joint separation grading MRI and AC joint separation grading x-ray. Both diagnostic tests will help determine injury grade and an appropriate treatment plan.

The treatment of an AC separation depends on the injury grade. Grades 1-3 are commonly treated with non-operative measures such as rest, ice medication and arm stabilization in a sling.

Certain patients with a grade 3 AC joint separation will need a surgical treatment to fully recover. The surgical technique most commonly performed by Dr. Millett involves the reconstruction of the CC ligaments and the removal of a small piece of the clavicle at the shoulder. Using a screw or suture loop, he will stabilize the joint which allows for a full recovery in most patients.

For more resources on the AC joint separation grading scale, or to determine your grade of injury with an AC joint separation grading x-ray and MRI, please contact the orthopedic office of Dr. Peter Millett.

Peter Millett, MD

Average rating:

39 reviews

Alexandra Thompson

Mar 23, 2024

by Alexandra Thompson on Peter Millett, MD

110%

Dr. Millett and his team did a SLAP tear repair and bicep tenodesis on my left shoulder. I use my arms as an artist, and love to swim in the ocean, surf, paddle, and telemark ski. So regaining full use of my shoulder and keeping my bicep attached was very important to me. Now, over two years later, my shoulder has the equivalent range of motion as my other arm and as before the injury, and no pain. After the first three months it felt so good and was so strong that - to my horror - I completely forgot my six-month follow-up.

Not only did Dr. Millett and his team make my arm as good as new, but having had the experience of such kindness and expertise throughout the process of surgery and recovery is like an added shoulder superpower.

Thank you Rita, Brooke, Jason, Sarah, Camille, Olivia, Dr. Millett and everyone! And see you soon when my husband comes in for his knee...

Jeff Chandler

Jan 31, 2022

by Jeff Chandler on Peter Millett, MD

Flawless procedure, Easy recovery

Dr. Millet's repaired my knee and tibia, following a botched operation by a different surgeon. That procedure was virtually pain free and I was weight bearing within a few days. That was 18 years ago and the knee is still strong. A few years after the knee incident, Dr Millet repaired my shoulder. My insurance company approved me for 3 months of disability following that surgery. I was off pain medication in 2 days and had 90% range of motion within a week. I withdrew my disability claim and returned to work within two weeks of surgery. I’m not a famous athlete—just a regular guy. Nonetheless, I was treated like an NFL at the Steadman clinic. Most notable was the time for recovery. Other surgeons perform their hour-long task in the OR and don’t involve themselves in the other functions. Peter and his team manages the entire process from diagnosis, anesthesia, nursing care, and therapy. He takes a holistic approach to patient care and doesn’t skip any steps.

Jenn West

Jul 2, 2021

by Jenn West on Peter Millett, MD

Saved My Life

I went to Dr. Millett after 7 knee surgeries (6 on my right and 1 on my left) and had seen 11 different surgeons who all refused to remove femur metal from my right leg. I am highly allergic to metal and the chronic pain was leaving me bedridden for 3.5wks out of a month. He personally wrote me back on my inquiry, listened to my concerns, scheduled my surgery within a week (due to insurance issues) and personally followed up with my recovery. The level of patient care from Dr. Millett and his ENTIRE team is above any care I have ever received in my 20 years of dealing with orthopedic surgeons. There are not enough words to describe the level of care, dedication and professionalism you receive from Dr. Millett and his staff.
My only disappointment is that I did not find him sooner!!!