A patient-friendly guide to shoulder separation: how it is graded, when surgery is needed, which reconstruction techniques surgeons use today, and what recovery looks like week by week.

What Is an AC Joint Separation?

The acromioclavicular (AC) joint sits at the top of the shoulder, where the collarbone (clavicle) meets the highest point of the shoulder blade (the acromion). Two sets of ligaments hold it together: the AC ligaments, which control front-to-back (horizontal) stability, and the coracoclavicular (CC) ligaments, which anchor the clavicle down to the coracoid process and control up-and-down (vertical) stability.

When these ligaments are stretched or torn, the clavicle can separate from the acromion. This injury is commonly called a shoulder separation or AC joint separation. It is different from a shoulder dislocation, which involves the ball-and-socket (glenohumeral) joint.

Common Causes of AC Joint Injury

Contact and collision sports: Football, rugby, hockey, wrestling and martial arts frequently produce AC injuries through tackles and hard landings.
A direct fall onto the point of the shoulder: This is the most typical mechanism, often seen in cycling, motorcycling, skiing and horse riding, where the shoulder strikes the ground with the arm tucked in.
A fall onto an outstretched hand: Force travels up the arm and can drive the shoulder upward, injuring the joint.
High-energy trauma: Road traffic accidents and workplace falls can cause more severe, higher-grade separations.

Signs and Symptoms

Pain at the top of the shoulder, localised over the AC joint and worse when lifting the arm overhead or reaching across the body.
A visible bump or step deformity, caused by the end of the clavicle riding higher than the acromion.
Swelling and bruising around the joint.
Weakness and reduced movement, especially with overhead activity.
Tenderness to touch directly over the joint.

How AC Joint Injuries Are Diagnosed

Diagnosis begins with a careful history and physical examination. The cross-body adduction test, in which the arm is brought across the chest, typically reproduces pain at the AC joint. The surgeon will also check for instability and assess neighbouring structures such as the rotator cuff.

X-rays are the key investigation. A bilateral Zanca view compares the injured and uninjured sides, and an axillary view shows any backward (posterior) displacement of the clavicle.
Stress or weighted views are occasionally used to unmask instability.
MRI helps assess ligament damage and associated injuries, such as labral or rotator cuff tears.
CT scans may be used to evaluate complex displacement or to plan surgery.

Rockwood Classification of AC Joint Separations

The Rockwood classification grades AC joint injuries into six types, which guide treatment decisions.

Type	Ligaments injured	Typical findings	Usual treatment
I	AC ligaments sprained; CC ligaments intact	No displacement on X-ray	Non-operative
II	AC ligaments torn; CC ligaments sprained	Mild upward displacement (under 25%)	Non-operative
III	AC and CC ligaments torn	Clavicle displaced 25–100% upward	Non-operative first for most; surgery considered for selected patients
IV	AC and CC ligaments torn	Clavicle displaced backward into or through the trapezius	Surgery
V	AC and CC ligaments torn; muscle attachments stripped	Severe upward displacement (100–300%)	Surgery
VI	AC and CC ligaments torn	Clavicle displaced below the coracoid (rare)	Surgery

Many surgeons further divide Type III injuries into IIIA (stable) and IIIB (unstable), as recommended by the ISAKOS classification. Unstable IIIB injuries are more likely to benefit from surgery.

When Is AC Joint Reconstruction Surgery Needed?

Most Type I and II injuries heal well with a sling, ice, pain relief and physiotherapy. Surgery is generally recommended for:

High-grade separations (Types IV, V and VI)
Type III injuries in overhead athletes, throwers and heavy manual labourers, or when symptoms persist after 3–6 months of structured rehabilitation
Chronic, painful instability that has not responded to conservative care
Cosmetic concerns about a prominent deformity, after a careful discussion of risks and benefits

Timing matters. Acute repair (ideally within 2–3 weeks of injury) allows the torn ligaments to heal around a fixation device. Chronic injuries usually require ligament reconstruction with a tendon graft, because the native ligaments no longer have healing potential.

AC Joint Reconstruction Surgery Techniques

Modern AC joint surgery aims to restore both vertical stability (CC ligaments) and horizontal stability (AC ligaments). The choice of technique depends on how old the injury is, its grade, the patient's activity level and the surgeon's experience.

1. Suspensory (Suture-Button) Fixation

A strong suture construct is passed through small drill tunnels in the clavicle and coracoid and secured with metal buttons on either side. This holds the clavicle in its reduced position while the CC ligaments heal. Single-tunnel and double-tunnel configurations are used; double-tunnel constructs more closely replicate the two parts of the CC ligament complex (conoid and trapezoid). The procedure is commonly performed arthroscopically or arthroscopically assisted through small incisions, and it is most effective for acute injuries.

2. Anatomic Coracoclavicular Ligament Reconstruction (ACCR)

For chronic injuries, a tendon graft is used to recreate the CC ligaments. The graft may be the patient's own hamstring tendon (autograft) or a donor tendon (allograft). It is looped under the coracoid and passed through tunnels in the clavicle at the anatomic attachment points of the conoid and trapezoid ligaments, then fixed with interference screws or buttons. Suture tape is often added to protect the graft while it incorporates.

3. Combined (Hybrid) Fixation with Graft Augmentation

Many surgeons combine suspensory fixation with a tendon graft, giving immediate mechanical strength from the implant and long-term biological stability from the graft. This approach is popular for chronic injuries and for high-demand athletes.

4. AC Ligament Repair or Reconstruction (Horizontal Stability)

Persistent front-to-back instability is a common cause of ongoing pain after CC-only fixation. Adding a repair or reconstruction of the superior AC ligament and capsule, often using a graft limb or suture tape across the joint, improves horizontal stability and overall outcomes.

5. Hook Plate Fixation

A plate is fixed to the clavicle with a hook that sits under the acromion, holding the joint reduced. It provides strong fixation but usually requires a second operation to remove the plate after a few months and can cause pain under the acromion. Its use has declined as arthroscopic techniques have improved.

6. Modified Weaver–Dunn Procedure

This classic open technique removes a small portion of the end of the clavicle and transfers the coracoacromial ligament to the clavicle to act as a substitute CC ligament. It is still used in some settings but is biomechanically weaker than anatomic graft reconstruction, so it is often augmented.

Arthroscopic vs Open AC Joint Surgery

Arthroscopic and arthroscopically assisted techniques use small incisions and a camera. They allow precise tunnel placement under the coracoid, less soft-tissue disruption, smaller scars and the chance to identify and treat associated injuries inside the shoulder. Open surgery remains useful for complex, chronic or revision cases, and for severe displacement where direct visualisation is helpful.

Preparing for Surgery

Comprehensive evaluation: Medical history, examination, and a discussion of work, sport and lifestyle goals.
Imaging review: X-rays, and MRI or CT where needed, to confirm the grade and plan tunnel positions.
Pre-habilitation: Gentle exercises to maintain shoulder motion and scapular control before surgery can make recovery smoother.
Practical planning: Arrange help at home for the first few weeks, as the operated arm will be in a sling.

AC Joint Reconstruction Rehabilitation Protocol

Rehabilitation is as important as the surgery itself. The goal is to protect the repair while it heals, then gradually restore movement, strength and function. The timeline below is a typical framework; your surgeon and physiotherapist will tailor it to your procedure and progress.

Phase	Timeframe	Goals	Typical activities
1. Protection	Weeks 0–6	Protect the repair; control pain and swelling	Sling at all times except hygiene and exercises; hand, wrist and elbow movement; gentle passive shoulder motion within set limits
2. Early motion	Weeks 6–12	Restore full range of motion	Wean off the sling; active-assisted then active movement; scapular setting; light isometric exercises
3. Strengthening	Months 3–4	Rebuild strength and endurance	Resistance band work, rotator cuff and scapular strengthening, progressive light weights
4. Return to activity	Months 4–6+	Return to sport and full work duties	Sport-specific and plyometric drills; contact sports usually at around 6 months with surgeon clearance

Precautions in the Early Weeks

Support the elbow in the sling to offload the reconstruction, as the weight of the arm pulls down on the clavicle.
Avoid lifting, pushing or pulling with the operated arm.
Avoid reaching across the body and lifting the arm above shoulder height until cleared.
Do not lie on the operated shoulder.

Key Exercises in Rehabilitation

Pendulum and passive range-of-motion exercises to prevent stiffness while the repair is protected.
Scapular stabilisation exercises, such as shoulder blade squeezes and controlled retraction, to restore normal shoulder mechanics.
Isometric exercises to activate the rotator cuff and deltoid without stressing the joint.
Resistance band strengthening for internal and external rotation, rows and extensions.
Progressive overhead and functional training in the later phases, building towards sport- or job-specific demands.

Returning to Sport and Work

Desk work: Often possible within 1–2 weeks, depending on comfort and travel.
Light manual work: Typically from around 3 months.
Heavy manual work and overhead sport: Usually around 4–6 months.
Contact and collision sports: Generally around 6 months, once full strength and motion are restored and the surgeon has given clearance.

Expected Outcomes of AC Joint Reconstruction

With appropriate patient selection and a well-executed rehabilitation programme, most patients achieve good to excellent shoulder function, reliable pain relief and a return to their previous level of activity. Anatomic reconstructions that address both vertical and horizontal stability tend to show the most durable results. A small degree of residual displacement on X-ray is common and often does not affect function.

Potential Risks and Complications

As with any surgery, AC joint reconstruction carries some risks:

Loss of reduction: Partial return of the deformity, the most common complication.
Fracture of the clavicle or coracoid through drill tunnels.
Implant irritation, sometimes requiring removal of buttons, screws or plates.
Infection and wound-healing problems.
Stiffness or persistent pain, sometimes needing extended physiotherapy.
Late AC joint arthritis or osteolysis of the end of the clavicle.
Rare nerve or blood vessel injury near the coracoid.

How to Reduce Your Risk

Choose a fellowship-trained shoulder or sports orthopaedic surgeon experienced in AC joint reconstruction.
Follow sling and activity restrictions carefully in the first six weeks.
Attend regular physiotherapy and follow-up appointments.
Report fever, increasing pain, wound redness or a new change in shoulder shape promptly.

Frequently Asked Questions

Can an AC joint separation heal without surgery? Yes. Most Grade I and II injuries, and many Grade III injuries, heal well with a sling, pain relief and a structured physiotherapy programme.

How long does recovery take after AC joint reconstruction? Most patients use a sling for about 6 weeks, regain full motion by about 3 months, and return to sport or heavy work between 4 and 6 months.

Is AC joint surgery done arthroscopically? Many modern AC joint procedures are arthroscopic or arthroscopically assisted, using small incisions. Chronic or complex cases may need a more open approach.

Will the bump on my shoulder go away after surgery? Surgery usually restores the normal contour of the shoulder, although a small residual prominence can remain in some patients.

What is the difference between a shoulder separation and a shoulder dislocation? A separation affects the AC joint between the collarbone and shoulder blade, while a dislocation affects the ball-and-socket joint of the shoulder.

Conclusion

AC joint separations range from mild sprains to severe dislocations. While most low-grade injuries recover without surgery, high-grade and persistently symptomatic injuries can be reliably treated with modern reconstruction techniques, from arthroscopic suture-button fixation to anatomic ligament reconstruction with a tendon graft. A personalised surgical plan, combined with a disciplined, phase-based rehabilitation programme, gives patients the best chance of a strong, stable and pain-free shoulder.

If you have a painful bump on your shoulder or persistent pain after a shoulder injury, consult an experienced sports orthopedic surgeon for a thorough evaluation and a treatment plan tailored to your goals.

Medical disclaimer: This article is for general information only and does not replace personalised advice from a qualified orthopedic surgeon or physiotherapist. Rehabilitation timelines vary with the procedure performed and individual progress.

AC Joint Reconstruction Surgery: Modern Techniques for AC Joint Separation and a Phase-by-Phase Rehabilitation Guide