Acromion and Collarbone: A Union You Don’t Want to Separate

Share Article

Hand and Upper Limb Orthopedic Surgeon Dr. Alejandro Badia Discusses AC Shoulder Joint Arthritis; Offers Patient Tips.

Dr. Alejandro Badia

Arthritis of the AC joint is characterized by gradual worsening of soreness and pain in front and on top of the shoulder.

Acromioclavicular. The word may tie the tongue, but if that shoulder joint develops osteoarthritis, the pain and stiffness will let you know exactly where it is located, according to Dr. Alejandro Badia, noted upper-limb expert and orthopedic surgeon and author of the recently published book Healthcare from the Trenches.

The acromioclavicular (AC) joint is formed by the connection of the collarbone (clavicle) with the acromion, the shoulder blade’s bony projection at top of shoulder. The AC is more frequently affected by arthritis, primarily osteoarthritis, than the lower portion of the shoulder where the arm (humerus) bone connects to the shoulder blade (glenohumeral joint), says Dr. Badia, founder and chief medical officer of the Badia Hand to Shoulder Center and OrthoNOW®.

Badia should know about AC injuries. He had successful arthroscopic procedure on left that may have been related to years of weightlifting. However, on his right, he still has some issues as he sustained a grade 3 separation 2 years ago after a fall in tennis. He now regrets not having had it fixed initially.

Arthritis of the AC joint is characterized by gradual worsening of soreness and pain in front and on top of the shoulder. The pain can radiate to the neck, causing headaches, and becomes especially acute if a patient extends the arm of the affected shoulder and reaches up and across the body, an action that occurs when pulling a seatbelt shut, for example. AC symptoms also may interrupt sleep when a person rolls onto the diseased shoulder, Dr. Badia notes.

The term “arthritis” actually applies to more than 100 different joint-related conditions, and multiple causative factors. Osteoarthritis is the most common type to settle in the AC joint. The chronic disease develops over time, causing a breakdown of cartilage, which is the hard tissue at the end of bones that form the joint; a thickening of joint bone; and edema or swelling of soft tissues, Dr. Badia says. “Cartilage serves as a shock absorber for joints. When it wears away, bone grinds on bone, and the result is pain, stiffness, swelling and loss of joint function.”

Advancing age is a major reason for development of osteoarthritis in the AC joint, but family history, gender, prior trauma or multiple “micro-injuries” to the top of the shoulder, and congenital weakness of the AC joint are all factors that promote development of the disease, says Dr. Badia.

Trauma to the AC joint is frequently called a shoulder separation, which is reported in the news as occurring to a football player or other athlete following a fall or hard contact with another player.

“Shoulder separation is not a shoulder dislocation,” Dr. Badia emphasizes. “Separation refers to damaged ligaments or other structures connecting the acromion and collarbone. A shoulder dislocation, on the other hand, happens when an injury forces the ball of the upper arm bone – the humerus – out of the shoulder socket. That type of injury is very painful and requires immediate treatment,” Dr. Badia says.

AC joint problems are also commonly nicknamed, “weightlifters shoulder,” because the “micro-injuries” incurred by weightlifters, boxers, racquetball players and other athletes due to repeated compression of the shoulder joint over time can lead to AC joint osteolysis. Osteolysis is a condition marked by symptoms not unlike those of joint arthritis, including top-of-shoulder pain, swelling and erosion of bone.

Some experts refer to joint osteoarthritis as a “wear-and-tear” disorder, but Dr. Badia emphasizes “it’s a myth to think arthritis is simply the result of joint overuse. Osteoarthritis is a disease.” He points to a study, published in the June 1, 2020 edition of JSES International, indicating that, in fact, “little is known about development of specific acromioclavicular joint osteoarthritis.” Study authors also report that “women have a higher chance of presenting with AC joint pain than men.”

Although osteoarthritis is not curable, “early therapy can slow its progress,” says Dr. Badia. Depending on severity of the disease, initial treatments may include warm or cold compresses; use of aspirin and other over-the-counter analgesics to relieve symptoms or prescribed anti-inflammatory, nonsteroidal medications; corticosteroid injections for moderate or more severe pain; and avoidance of certain activities – like lifting or swinging a golf club – which can aggravate the AC joint.

“Shoulder surgery is only infrequently necessary, but, if performed, can be done successfully on an outpatient basis,” Dr. Badia says. “The standard approach is to remove a small piece from the end of the clavicle to prevent friction between it and the shoulder blade, the triangular bone between the clavicle and the humerus. This procedure maintains the AC joint ligaments, which are important to the stability of the AC joint.” Dr. Badia adds that the surgery has been done with small open incision for years but Dr. Badia and many shoulder specialists now do the AC resection (Mumford procedure) all arthroscopically. No scars and minimal post-op discomfort.

Authors of a single-case study in a 2019 edition of BMJ Case Reports write that injections of mesenchymal stem cells harvested from a patient’s own adipose (fat) tissue – tissue that helps insulate the body – show promise in the treatment of AC shoulder joint disorders due to age-related osteoarthritis, post-traumatic osteoarthritis and joint osteolysis. However, Dr. Badia concurs with the scientists that a patient’s age may affect outcome results using stem cells and that more research is needed to determine the treatment’s long-term effectiveness.

Meanwhile, Dr. Badia offers these tips to anyone suffering mild or moderate AC joint pain:

  • Talk to a health care professional about shoulder exercises that strengthen muscles around the joint, enhance flexibility and range of motion and can reduce pain and stiffness.
  • Avoid maneuvers that aggravate or put extensive strain on the joint. You may have to put down the golf clubs – at least from time to time.
  • Maintain a healthy lifestyle. Stop smoking, reduce alcohol consumption, and achieve a weight and body mass index that are within normal range for one’s age and height.

“Most importantly, someone experiencing ongoing shoulder pain that is affecting their activities should contact an orthopedic specialist for consultation and treatment as soon as possible. Arthritis of the AC joint and other areas of the shoulder affects quality of life and may lead to additional, more serious problems like shoulder impingement and tendinitis,” says Dr. Badia.

Bio: Alejandro Badia, MD, FACS, is an internationally renowned hand and upper-limb surgeon and founder of Badia Hand to Shoulder Center and OrthoNOW®, a network of walk-in orthopedic centers. Dr. Badia is the author of [Healthcare from the Trenches.

Share article on social media or email:

View article via:

Pdf Print

Contact Author

Melissa Chefec
Email >
Visit website