AC Joint Separation Diagnosis and Treatment

A separated shoulder is one of the most frequently underestimated injuries in orthopedics. Patients are told the visible bump is cosmetic and that the joint will settle on its own, which is true for some injuries and leaves others with a shoulder that aches through every overhead reach, gives way under load, and never fully returns to what it was.

Steven Struhl, MD did not learn the reconstruction he performs for this injury, he invented it. The United States Patent and Trademark Office granted him Patent 8,162,997 in 2012, the orthopedic device manufacturer Smith and Nephew later acquired the design, and he has since published his long term outcomes in The American Journal of Sports Medicine after performing more than 200 of these reconstructions. He is board certified in both orthopedic surgery and sports medicine, has practiced in New York since 1991, and patients travel from across the country to his Manhattan and White Plains offices for the procedure that carries his name on the patent.

What Is the AC Joint?

The acromioclavicular joint sits at the top of the shoulder where the outer end of the collarbone meets the acromion, the highest point of the shoulder blade. It is a small joint carrying a large responsibility, since it transfers force between the arm and the trunk every time the shoulder is loaded.

Two ligament systems hold it together. The acromioclavicular ligaments surround the joint itself and control front to back movement. The coracoclavicular ligaments run from the collarbone down to the coracoid process of the shoulder blade and control vertical movement, which is why they matter most when the joint separates.

What Causes an AC Joint Separation?

The mechanism is remarkably consistent. A fall directly onto the point of the shoulder drives the shoulder blade downward while the collarbone stays where it is, and the ligaments absorb that force until they cannot. Cycling crashes, contact sports, and ordinary falls on ice account for the majority of cases.

• Cycling Accidents: going over the handlebars and landing on the point of the shoulder.
• Contact Sports: direct impact in football, hockey, rugby, lacrosse, and martial arts.
• Falls On Ice: landing on the shoulder rather than an outstretched hand.
• Motor Vehicle Accidents: direct impact against the door frame or from a motorcycle fall.

The direction of the force matters more than its severity. A blow that drives the shoulder blade downward while the collarbone stays fixed is what tears the ligaments, and understanding that distinction is what makes the reduction reliable during surgery. The mechanism of injury, with clinical demonstration video, is covered in detail here.

AC Joint Separation Grades

Grading determines treatment, and it is the thing most commonly gotten wrong.

• Grade One: the acromioclavicular ligaments are stretched, with no visible displacement.
• Grade Two: the acromioclavicular ligaments tear while the coracoclavicular ligaments hold.
• Grade Three: both ligament systems rupture completely, producing the visible bump.
• Grade Four: the collarbone displaces backward through the trapezius muscle.
• Grade Five: severe upward displacement exceeding one hundred percent of normal.
• Grade Six: the collarbone displaces downward, a rare pattern requiring prompt surgical care.

A standard shoulder film taken with the arm supported can make a grade three look like a grade two, and that single misread sends a patient down the wrong treatment path for months. How AC separation grades are determined covers the imaging and examination that get it right.

“Patients are told the bump is cosmetic, and for some people that is true. But if you cannot press overhead without aching, or you cannot carry a bag on that shoulder, that is not cosmetic. That is a joint that is not doing its job.” – Steven Struhl, MD, Board Certified Orthopedic and Sports Medicine Surgeon

AC Joint Separation Symptoms

• A Visible Bump: a prominence at the top of the shoulder where the collarbone rides upward.
• Pain On Top: discomfort localized precisely at the joint rather than deep inside the shoulder.
• Overhead Weakness: difficulty pressing, reaching, or carrying weight through the arm.
• Pain Across The Body: discomfort when reaching the opposite shoulder, which loads the joint directly.
• A Sense Of Instability: the feeling that the shoulder shifts or gives under load.
• Sleep Disruption: difficulty lying on the affected side, common in higher grade injuries.

AC Joint Separation Treatment Options

Grades one and two heal without surgery in the great majority of cases. Grade three is the genuine decision, and grades four through six generally require reconstruction.

• Sling Immobilization: short term support while the ligaments heal in lower grade injuries.
• Physical Therapy: restoring motion and strengthening the muscles that support the joint.
• Injection Therapy: targeted injection for persistent joint pain in selected patients.
• Surgical Reconstruction: rebuilding the coracoclavicular ligaments with the patented construct.

The Patented AC Joint Reconstruction

The reconstruction restores the torn anchor between the collarbone and the shoulder blade using two small titanium buttons joined by a continuous, knotless suture loop manufactured to a fixed length. One button seats above the clavicle and the other beneath the coracoid, and because there is no knot, the two most common failure modes are removed from the equation.

“The problem with the older repairs was never the surgeon’s technique, it was the construct. A knot can slip and a knot can break. Removing the knot entirely removes the most common way these repairs fail.” – Steven Struhl, MD

Published results in The American Journal of Sports Medicine followed thirty five patients for a mean of 5.2 years, with individual patients followed as long as twelve years. The construct remained stable in all but one patient, eighty seven percent maintained a coracoclavicular interval difference under two millimeters, mean functional scores reached 98 out of 100, and there were no infections, no fractures, and no perioperative complications.

Clinical Demonstration of mechanism of injury

A complete AC joint separation creates a deformity. The protruding bump is the edge of the clavicle. While it seems obvious that the problem is the protruding bone that needs to be pushed back down, the solution actually requires just the opposite! The scapula needs to be pushed back up to meet the clavicle and supported there with adequate fixation. The video demonstrates that reducing the joint requires pushing the scapula “up” to the clavicle, not the other way around:

How understanding the mechanism of injury leads to successful surgery with the Triple Endobutton Technique.

The importance medial instability that occurs from an AC joint separation

After an AC joint dislocation not only does the scapula drop down and away from the clavicle but it also results in significant medial instability.  This video shows how this instability leads to symptoms and how the Triple Endobutton uniquely addresses it leading to successful surgical outcomes.

Learn More About AC Joint Separation

Understanding Your Injury

• AC Separation Symptoms: what the injury feels like in the first days and the months after.
• What Is the AC Joint: the anatomy of the joint and the ligaments that stabilize it.
• AC Separation Grading: how grades one through six are determined and why accuracy matters.

Deciding on Treatment

• Grade 3, Surgery or Not: the case for and against operating on a complete separation.
• Am I a Candidate: who benefits from reconstruction and who does not.
• Timing of Surgery: why the interval between injury and surgery changes the operation.

The Surgery and the Evidence

• The Patented Technique: how the continuous loop double button reconstruction is performed.
• AC Joint Recovery Time: what the weeks and months after reconstruction actually involve.
• Patient Case Studies: individual patient histories from injury through return to activity.

Frequently Asked Questions About AC Joint Separation

How do I know if my shoulder bump is an AC joint separation?

A visible prominence at the top of the shoulder following a fall onto that shoulder is the classic presentation, and it is usually accompanied by pain located precisely at the joint rather than deep inside. Confirming the grade requires examination plus imaging, ideally including comparison views, since a single standard film taken with the arm supported can understate the injury.

Can AC joint injuries heal without surgery?

Grades one and two heal without surgery in the great majority of cases. Grade three is genuinely debated, and the decision turns on the accuracy of the grade, the degree of instability on examination, the demands placed on the shoulder, and whether symptoms persist past the expected healing window. Grades four through six generally require reconstruction.

What makes Dr. Struhl’s approach different?

He holds United States Patent 8,162,997 for the device used in the reconstruction, a continuous loop construct with no knot to slip or break, and he has published long term outcomes for the technique in The American Journal of Sports Medicine rather than relying on case reports. He has performed more than 200 of these reconstructions.

What is the recovery time after AC joint surgery?

Most patients wear a sling for the first several weeks while biologic healing takes hold, begin supervised motion work shortly afterward, and progress toward unrestricted activity over the following months. The exact timeline depends on the grade of the injury and the demands of the patient’s sport or occupation.

Can an old AC joint separation still be repaired?

Yes. Twenty six of the thirty five patients in the published outcomes study had chronic dislocations rather than acute injuries, and their results were comparable, so an injury that is months or even years old remains worth evaluating rather than accepting as permanent.

Is this procedure covered by insurance?

AC joint reconstruction is a medically indicated procedure and is covered by most insurance plans when the injury and symptoms support it. Our staff verifies benefits before surgery is scheduled and reviews any out of pocket obligation with you in advance.

Why Patients Choose Dr. Struhl for AC Joint Repair

• Board Certified Twice: orthopedic surgery plus subspecialty certification in sports medicine.
• Fellowship Trained: sports medicine fellowship completed at Penn State University.
• NYU Faculty: teaching appointment at NYU School of Medicine and Hospital for Joint Diseases.
• US Open Consultant: medical consultant to the United States Open tennis tournament.
• Brooklyn Nets Affiliation: medical director for Sportscare Physical Therapy.
• Patent Holder: inventor of United States Patent 8,162,997 for AC joint reconstruction.
• In Practice Since 1991: more than three decades of orthopedic surgical experience.

Schedule an AC Joint Evaluation in New York City

An accurate grade is the first thing a separated shoulder needs, and it is the thing most commonly gotten wrong, which is why so many patients arrive here months after being told nothing more could be done. Dr. Struhl evaluates acromioclavicular injuries at both the Manhattan and White Plains offices, reviews outside imaging for patients traveling from farther away, and will say plainly when an injury does not call for surgery. Call the New York City office at (212) 207-1990 or the Westchester office at (914) 328-4111 to arrange an evaluation, and bring any X-rays or MRI images you already have.