Acromioclavicular Injuries

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Dr Kau Chung Yuan (许医生)


MRCS (Ireland)

MMed (Ortho)

FRCSEd (Ortho)


What are Acromioclavicular Injuries?

Acromioclavicular injuries involve the acromioclavicular joint, where the clavicle meets the acromion of the scapula, which is crucial for shoulder movement.

These injuries range from mild sprains to severe dislocations, classified into six grades based on the damage extent. Accurate diagnosis and effective treatment are essential for restoring function and preventing long-term complications.

The 6 Grades of Acromioclavicular Injuries

The 6 grades of acromioclavicular injuries classify the severity and type of shoulder joint damage by the Rockwood system, guiding treatment and management strategies.

Grade I

A mild injury where the AC joint ligaments are slightly damaged but not torn. The joint remains aligned, and there is minimal loss of function.

Grade II

Moderate injury with partial tearing of the AC joint ligaments and possibly the coracoclavicular (CC) ligaments, leading to slight displacement of the joint but without complete separation.

Grade III

Severe injury involving complete tearing of the AC and CC ligaments, causing noticeable displacement of the joint. This grade often results in a visible bump on the shoulder.

Grade IV-VI

These grades represent progressively more severe injuries, with the clavicle displaced backward (IV), downward into or through the muscle of the shoulder (V), or horizontally (VI). These injuries are less common but require more complex treatment approaches.

Symptoms of Acromioclavicular Injuries

Symptoms of acromioclavicular injuries vary depending on the injury’s grade, highlighting the range and intensity of discomfort and physical limitations experienced.

  • Immediate pain at the top of the shoulder following trauma or fall, worsening with overhead movement or when carrying the arm across the body.
  • Swelling and bruising around the joint area, often accompanied by a noticeable bump on the shoulder due to clavicle displacement.
  • Limited shoulder movement makes it challenging to raise the arm or perform activities that require overhead motion.
  • Weakened grip strength on the affected side, affecting the ability to grasp or carry objects.
  • Severity of symptoms varies according to the injury grade, with higher grades showing more significant physical deformities and functional impairments.

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Causes and Risk Factors

Causes and risk factors of acromioclavicular injuries identify the conditions and activities that explain the onset or that increase the likelihood of sustaining shoulder joint damage.

  • Direct impact
    Direct Impacts to the shoulder, such as from a fall directly onto the shoulder or outsrtetched hand, or a blow during contact sports, is a primary cause of AC injuries.
  • Previous shoulder injuries
    These can predispose an individual to AC joint injuries by weakening the joint’s structural integrity.
  • Age and physical condition
    Younger, active individuals are more likely to experience these injuries due to higher involvement in physical activities.

Diagnosis of Acromioclavicular Injuries

Diagnosis of acromioclavicular injuries involves a combination of different procedures to accurately identify the nature and extent of the injury.

  • Clinical Examination
    Involves assessing the injury’s history, examining pain, tenderness, and visible deformities at the AC joint, and testing the range of motion and shoulder strength.
  • Radiographs (X-rays)
    Used to assess displacement extent and fractures. Various positions might be used to evaluate AC joint stability.
  • Ultrasound Imaging
    Helps in assessing soft tissue damage, including ligament tears and the condition of surrounding muscles.
  • Magnetic Resonance Imaging (MRI)
    Occasionally used for detailed images of soft tissues, including ligaments and cartilage, particularly if considering surgery.

Non-Surgical Treatments

Non-surgical treatment is often effective for Grade I to III injuries, aiming to manage symptoms and promote healing while maintaining shoulder function.

  • Rest and Ice: Initial management includes resting the injured shoulder and applying ice to reduce swelling and pain.
  • Sling Support: Using a sling helps immobilize the shoulder, allowing the AC joint to heal and reducing discomfort.
  • Pain Management: Over-the-counter pain relievers and anti-inflammatory medications can alleviate pain and swelling.
  • Physical Therapy: After the acute phase, physical therapy focuses on restoring range of motion, strengthening shoulder muscles, and reducing the risk of future injuries.
  • Modifications in Activities: Avoiding activities that exacerbate the injury until fully healed is crucial for recovery.

Surgical Interventions

Generally recommended for severe AC joint injuries (Grades IV to VI) or when non-surgical treatments fail to relieve symptoms in less severe injuries.

Reconstruction of Ligaments

Involves repairing and reconstructing the torn ligaments to restore the joint’s normal alignment and function.

Open Reduction and Internal Fixation (ORIF)

This procedure realigns the joint and secures it with hardware, such as screws or plates, to maintain proper position during healing.

Arthroscopic Surgery

A minimally invasive option that allows for the repair of ligaments and the removal of damaged tissue with smaller incisions, potentially resulting in quicker recovery times.


Dr. Kau Chung Yuan

MBBS (S’pore)

MRCS (Ireland)

MMed (Ortho)

FRCSEd (Ortho)

Dr Kau (许医生) is a Fellowship trained Orthopaedic Surgeon with a subspecialty interest in Hip and Knee surgery and has been in practice for more than 15 years.

He is experienced in trauma and fracture management, sports injuries, and joint replacement surgery.

  • Fellow of the Royal College of Surgeons Edinburgh, Orthopaedics (FRCS, Edin) 2014
  • Master of Medicine (Orthopaedics), Singapore (MMed) 2013
  • Member of the Royal College of Surgeons Ireland (MRCS, Ire) 2009
  • Bachelor of Medicine and Surgery (MBBS, Singapore) 2004

Prevention Methods

Prevention methods for acromioclavicular injuries focus on strategies to reduce the risk of shoulder joint damage through proper technique, conditioning, and protective measures.

  • Strengthening Exercises
    Focus on shoulder and upper body strength to provide better support and stability to the AC joint.
  • Proper Technique
    Ensuring correct form during sports and physical activities to minimize undue stress on the shoulder.
  • Use of Protective Gear
    Wear appropriate protective equipment in contact sports to shield the shoulder from direct blows and falls.
  • Ergonomic Adjustments
    Making changes to work and daily activity setups to avoid repetitive stress and awkward positions that could harm the shoulder.
  • Warm-Up and Stretching
    Incorporating a routine of warm-up exercises and stretching before engaging in physical activity enhances flexibility and reduces the risk of injuries.

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Patient Feedback

Ethan Chan
Dr. Kau is an exemplary doctor who is experienced in his field and is very patient with his patients. He walked me through the details of my knee condition and addressed all my concerns. Thanks to Dr. Kau, I had a better understanding of my ACL and MCL injury and the various treatment options available. His advice and treatment have been very valuable to me.
Ming Lee Chua
Dr Kau was very careful and explained clearly the surgery procedures. After surgery, the care while I was in hospital was closely monitored and he even came during weekends! The hip so far has recovered and healed. His ‘predictions’ of when what can happen are so accurate. Trust him.
Teo Pek Suan Diana
I had a very successful total hip replacement done by Dr Kau 4 years ago. 4 months after the operation I was back walking, cycling and swimming. The beautiful job gave me much confidence Dr Kau is most professional and has such great doctor patient communication.

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    Frequently Asked Questions (FAQs)

    Can AC joint injuries heal on their own?

    Mild AC joint injuries (Grade I and II) can often heal with appropriate non-surgical treatment, including rest, ice, and physical therapy. However, more severe injuries may require surgical intervention to restore joint function and stability.

    How long does recovery from an AC joint injury take?

    Recovery times vary depending on the injury’s severity and the treatment approach. Non-surgical treatments for mild injuries may allow for a return to normal activities within a few weeks, whereas surgical recovery can take several months, followed by rehabilitation.

    Are there any long-term effects of AC joint injuries?

    While many individuals recover fully from AC joint injuries, some may experience chronic pain, decreased strength, or reduced range of motion, especially if the injury is severe or not adequately treated.

    Is it possible to return to high-impact sports after recovering from an AC joint injury?

    Yes, many individuals can return to high-impact sports after fully recovering from an AC joint injury. The key to a successful return involves completing a comprehensive rehabilitation program tailored to restore strength, flexibility, and endurance to pre-injury levels.