Overview
The acromioclavicular joint is where the outer end of the collarbone meets the shoulder blade. It is held down by two coracoclavicular ligaments running from the underside of the clavicle to the coracoid; when those tear in a high-grade separation the shoulder blade and arm drop away from the clavicle, leaving the visible bump. AC joint reconstruction rebuilds those ligaments with a tendon graft backed by a suture-button construct, so the clavicle returns to its anatomic position and stays there while the graft heals.
The expected outcome is a shoulder with normal contour that can bench press, carry and reach overhead without the ache of a chronically displaced joint. The procedure is arthroscopically assisted and outpatient at Bayside Surgery Center.
Who It's For
Reconstruction is recommended for type IV, V and VI separations, in which the clavicle is displaced backward through the trapezius or more than twice the normal ligament distance upward, because those injuries do not do well in a sling. Type III separations, with both ligament groups torn and the clavicle sitting fully above the acromion, are decided individually. Dr. O'Donnell recommends surgery for a type III in an overhead athlete, a heavy manual worker, or a patient who still has pain, weakness with pressing, or overhead fatigue after three months of non-operative care. Chronic separations with persistent symptoms are reconstructed the same way.
Type I and II sprains, with the joint still aligned, heal with a sling for one to two weeks and a therapy program. Most type III separations in non-overhead athletes also do well without an operation, accepting a cosmetic bump. See AC joint injury for how the grade is determined. A patient over 40 with pain at the top of the shoulder and no history of a separation more often has AC joint arthritis, treated with an injection or an arthroscopic resection of the clavicle end (see shoulder arthroscopy).
An X-ray showing a raised clavicle is not by itself a reason to reconstruct the joint. Dr. O'Donnell recommends the operation only when the grade on imaging, the exam findings and the symptoms agree, and, for a type III separation, when three months of non-operative care have not restored function. The AC joint injury page explains how the finding is weighed against the exam.
What the Procedure Involves
Surgery is performed under an interscalene nerve block plus general anesthesia. Dr. O'Donnell begins with an arthroscopic inspection, since a high-energy separation can tear the labrum or rotator cuff as well, and uses the arthroscope to expose the base of the coracoid from inside the shoulder without a large open dissection.
Through a small incision over the clavicle, the bone is reduced to its normal position and a tendon graft, usually a semitendinosus allograft, is looped under the coracoid and passed through two drill holes in the clavicle to recreate the conoid and trapezoid ligaments in their anatomic positions. The graft is tensioned and fixed with interference screws, and a suture-and-button construct runs alongside it to protect the graft while it heals. The remaining graft reinforces the AC joint capsule, which controls the backward displacement that a coracoclavicular repair alone does not. In an acute injury within about three weeks, Dr. O'Donnell may repair the native ligaments with the suture-button construct alone; the graft is always used for chronic separations, where the native ligaments have scarred and cannot be relied on.
The operation takes about 90 minutes. The arm is placed in a sling that supports its weight, and patients leave the same day.
Risks & How They Are Minimized
The most important risk is loss of reduction, meaning the clavicle drifts back upward as the graft stretches or the fixation loosens. This is why the sling is worn for six weeks and why lifting, carrying and bearing weight through the arm are prohibited for six to eight weeks: the downward pull of the arm is exactly the load the reconstruction has to resist. Anatomic tunnels and a graft backed by a button construct give the strongest resistance to drift. Clavicle or coracoid fracture through a tunnel is a recognized complication, minimized by keeping tunnels small, well spaced and away from the edge of the bone.
Infection is uncommon and is guarded against with preoperative antibiotics and a short incision. The skin over the clavicle is thin, so hardware is kept low-profile. Numbness in a patch of skin below the incision is common and usually fades. Stiffness is prevented by early passive motion within the 90° limit. Blood clots are rare after shoulder surgery; patients walk the same day and take aspirin if they have risk factors.
Recovery & Rehabilitation
Dr. O'Donnell's protocol protects the graft from the weight of the arm for six weeks and delays overhead and pressing loads until twelve weeks.
| Phase | Timing | What happens |
|---|---|---|
| Maximum protection | Weeks 0–6 | Sling at all times, arm supported when upright. Pendulums and passive motion with flexion and abduction limited to 90°, passive rotation in the scapular plane, gentle scapular isometrics, ice. No active elevation or loading through the arm. |
| Motion | Weeks 6–12 | Sling discontinued at about 6 weeks. Active-assisted then active motion progressed to full, overhead motion added gradually, light scapular and cuff strengthening. No heavy lifting. |
| Strengthening | Weeks 12–16 | Progressive resistive cuff, deltoid and periscapular strengthening; overhead and pressing loads begin after 12 weeks; endurance work. Advance at 80% of the strength of the other side. |
| Return to activity | Months 4–6 | Advanced strengthening and plyometrics, sport- or job-specific progression. Contact and collision sport typically about 5–6 months. |
Desk work is possible within a week in the sling, driving at about six weeks, running from about three months, and bench pressing, overhead lifting, road cycling, tackling and sailing by five to six months.
Protocol summary
The sling is worn for six weeks to carry the weight of the arm. Active abduction or forward flexion above 90° is not permitted for six weeks, lifting, carrying, pushing and weight bearing through the arm are prohibited for six to eight weeks, and cross-body reaching and shrugging are avoided early because both load the reconstruction directly.
Phase I ends after six weeks of protected healing with comfortable motion in the allowed range. Full active motion with normal scapular mechanics is required before overhead and pressing loads begin at twelve weeks, and symmetric strength before contact sport at five to six months.
Physical Therapy Protocol
Acromioclavicular (AC) Joint Reconstruction PDF ↗Frequently Asked Questions
Does a grade 3 AC separation need surgery?
Not always. Many type III separations in patients who do not work or play overhead settle with a sling and therapy, leaving a bump but a functional shoulder. Dr. O'Donnell recommends reconstruction for a type III in an overhead athlete or heavy manual worker, and for anyone still troubled by pain or weakness after three months of non-operative care.
Can an AC joint separation be fixed years later?
Yes. Chronic separations are reconstructed with a tendon graft rather than a repair of the original ligaments, which have scarred and cannot be relied on. The rehabilitation timeline is the same as for an acute reconstruction, and the arthritic end of the clavicle is sometimes trimmed at the same time.
How long do I wear a sling, and when can I drive, after AC joint reconstruction?
Six weeks in the sling, longer than after most shoulder operations, because the weight of the hanging arm is the exact force the reconstruction has to resist while the graft heals. It comes off for showering and the passive exercises taught in the first week. Driving resumes at about six weeks once the sling is off.
When can I lift weights or return to contact sport after AC joint reconstruction?
Light cuff and scapular strengthening begins at six weeks. Overhead and pressing loads, including bench press, wait until after twelve weeks. Contact and collision sport is cleared at about five to six months when strength is symmetric. The full criteria are in the AC joint reconstruction protocol.
Will the bump on my shoulder go away after surgery?
Reconstruction returns the clavicle to its normal position, so the deformity is corrected. A small amount of settling as the graft matures is common and does not affect function; a return of the full bump means the reduction has been lost, which is why the six-week sling and lifting restrictions matter.
This page is for general education and is not a substitute for a medical evaluation. The right procedure depends on your individual diagnosis, anatomy, and goals. Kevin O'Donnell, MD sees patients from Coral Gables, Miami, Brickell, Pinecrest and Coconut Grove at 475 Biltmore Way, and out-of-town patients by telemedicine.