The acromioclavicular (AC) joint is a small joint located above the shoulder, where the acromion on the shoulder blade meets the clavicle bone. This joint plays a crucial role for stabilising the shoulder complex and facilitating various arm movements.
The AC joint is a diarthrodial joint, meaning it allows for movement in multiple directions. It is classified as a plane-type synovial joint, with articular surfaces covered in hyaline cartilage and surrounded by a joint capsule filled with synovial fluid.
The main functions of the AC joint include:
Transmitting Forces: The AC joint helps transmit forces from the upper limb to the axial skeleton, providing stability and support during activities such as lifting, pushing, and pulling.
Allowing Mobility: While the AC joint itself has limited mobility, it contributes to the overall mobility of the shoulder complex by allowing for slight movements, such as rotation and elevation of the arm.
Absorbing Shock: The AC joint acts as a shock absorber, dissipating forces and reducing impact on the shoulder during physical activities and movements.
The stability of the AC joint is primarily maintained by several ligaments, including the acromioclavicular ligament, coracoclavicular ligaments (consisting of the conoid and trapezoid ligaments), and the capsule surrounding the joint. These ligaments help prevent excessive movement and dislocation of the clavicle relative to the acromion.
Injuries or conditions affecting the AC joint, such as sprains, separations, arthritis, or osteolysis, can lead to pain, swelling, instability, and limited range of motion in the shoulder. Treatment for AC joint injuries vary depending on the severity of the condition and may include conservative measures such as rest, ice, physical therapy, and in some cases, surgical intervention to repair or stabilize the joint.
What types of conditions occur at the AC joint?
The acromioclavicular (AC) joint is prone to various types of conditions, often resulting from trauma, overuse, or degeneration. Some common conditions affecting the AC joint include:
AC Joint Sprain: This occurs when the ligaments surrounding the AC joint are stretched or torn, typically due to a fall onto the shoulder or a direct impact.
AC Joint Arthritis: Arthritis can develop in the AC joint over time, leading to pain, stiffness, and reduced range of motion. Osteoarthritis is the most common type of arthritis affecting this joint.
AC Joint Separation: This occurs when the ligaments connecting the acromion and clavicle are completely torn, resulting in a visible bump or deformity at the top of the shoulder.
AC Joint Osteolysis: Also known as distal clavicle osteolysis, this condition involves the breakdown of bone tissue in the distal end of the clavicle, leading to pain and weakness in the shoulder.
AC Joint Degeneration: Degeneration of the cartilage within the AC joint can occur with age or as a result of repetitive stress, leading to pain and inflammation.
AC Joint Impingement: This condition involves compression of the tissues within the AC joint, often due to abnormal movement or alignment of the shoulder structures, resulting in pain and limited range of motion.
AC Joint Bursitis: Inflammation of the bursa (a fluid-filled sac) located near the AC joint can cause pain, swelling, and tenderness in the shoulder region.
Treatment for AC joint conditions depends on the specific diagnosis and severity of the condition but may include rest, ice, physiotherapy, medications, injections, and in some cases, surgery.
Treatment and prognosis
The treatment and prognosis of an AC joint injury depend on several factors, including the severity of the injury, the patient’s age and activity level, and any associated injuries. Here’s a general overview:
Conservative Treatment: For mild to moderate AC joint injuries, conservative treatments are often effective. These may include:
Rest: Avoiding activities that exacerbate pain and inflammation.
Ice: Applying ice packs to the affected area to reduce swelling and pain.
Pain Management: Over-the-counter pain medications such as acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs) can help manage pain and inflammation.
Immobilisation: Using an arm sling or brace to immobilise the shoulder joint and allow it to heal.
Physiotherapy: Once pain and swelling decrease, physiotherapy exercises can help improve range of motion, strength, and stability in the shoulder joint.
Corticosteroid Injections: In some cases, corticosteroid injections may be used to reduce inflammation and pain in the AC joint.
Surgical Treatment: Severe AC joint injuries, such as complete ligament tears or significant joint displacement, may require surgical intervention. Surgical options include:
AC joint reconstruction: Surgically repairing or reconstructing the damaged ligaments using sutures or grafts.
AC joint stabilization: Using hardware such as screws or suture anchors to stabilize the joint and restore alignment.
Distal clavicle excision: Removing a portion of the distal end or lateral clavicle to alleviate pain and improve joint function, especially in cases of AC joint arthritis or osteolysis.
Prognosis: The prognosis for AC joint injuries varies depending on the severity of the injury and the chosen treatment approach. Mild to moderate injuries typically respond well to conservative treatment, with most patients experiencing significant improvement in symptoms within a few weeks to a few months. However, severe injuries or cases requiring surgery may have a longer recovery period, and full recovery may take several months.
In most cases with appropriate treatment and rehabilitation, many individuals return to their previous level of activity and function. However, some may experience lingering symptoms or long-term issues, particularly in cases of chronic instability or arthritis. Regular follow-up with a healthcare provider and adherence to a structured rehabilitation program are essential for optimizing outcomes and preventing recurrence.
What are the results of AC joint surgery?
The results of AC joint surgery can vary depending on several factors, including the specific type of surgery performed, the severity of the injury or condition being treated, the patient’s age and overall health, and adherence to post-operative rehabilitation protocols. Here are some general outcomes associated with common AC joint surgeries:
AC Joint Reconstruction:
This surgery aims to repair or reconstruct the damaged ligaments of the AC joint.
Results can vary but often include improved stability and function of the shoulder joint.
Patients may experience a reduction in pain and improved range of motion, particularly in cases of AC joint instability or ligamentous laxity.
AC Joint Stabilization:
Stabilization procedures involve using hardware such as screws or suture anchors to stabilize the AC joint and restore alignment.
Results can include reduced pain, improved shoulder function, and decreased risk of recurrent dislocations or subluxations.
Patients may require a period of immobilization followed by gradual rehabilitation to regain strength and mobility in the shoulder joint.
Distal Clavicle Excision:
This surgery involves removing a portion of the distal end or lateral clavicle to alleviate pain and improve joint function, particularly in cases of AC joint arthritis or osteolysis.
Results typically include reduced pain and improved range of motion, particularly in overhead activities.
Patients may experience some loss of stability in the AC joint, particularly with extreme ranges of motion or heavy lifting.
Overall, the majority of patients who undergo AC joint surgery experience significant improvement in symptoms and function. However, it’s important to note that surgery carries risks, and outcomes can vary from person to person. Complications such as infection, stiffness, hardware failure, or recurrent instability may occur in some cases.
Additionally, full recovery from AC joint surgery often requires a period of post-operative rehabilitation, including physical therapy to regain strength, flexibility, and function in the shoulder joint. Patients should follow their surgeon’s recommendations closely and participate actively in their rehabilitation program to optimize outcomes and minimize the risk of complications.
What is an AC joint separation?
An AC joint separation, also known as an acromioclavicular joint separation or AC joint dislocation, is an injury involving the disruption of the ligaments that stabilize the joint between the acromion (part of the scapula or shoulder blade) and the clavicle (collarbone).
This injury commonly occurs due to a direct blow to the shoulder or a fall onto an outstretched arm. The force of impact can cause the acromion and clavicle to be forced apart, leading to varying degrees of ligament damage and joint displacement.
AC joint separations are classified into different grades based on the severity of the injury:
Grade I: Mild sprain or partial tearing of the ligaments, with minimal or no joint displacement.
Grade II: Moderate injury with partial tearing of the ligaments and noticeable joint displacement, but the joint remains partially aligned.
Grade III: Severe injury with complete tearing of the ligaments, resulting in significant joint displacement and often a visible bump or deformity at the top of the shoulder.
Grade IV-VI: These are less common and involve additional damage to surrounding structures like the coracoclavicular ligaments or even displacement of the clavicle into or through the trapezius muscle.
What is the treatment for AC joint separation?
The treatment for AC joint separation depends on the severity of the injury, which is typically classified into different grades. Here’s an overview of treatment options for each grade:
Grade I and II:
Conservative treatment is often recommended for mild to moderate AC joint separations.
Rest: Avoiding activities that aggravate symptoms and allowing the ligaments to heal.
Ice: Applying ice packs to the affected area to reduce pain and inflammation.
Pain management: Over-the-counter pain medications such as paracetamol or non-steroidal anti-inflammatory drugs (NSAIDs) can help manage pain and inflammation.
Immobilization: Using a sling or brace to immobilize the shoulder joint and promote healing.
Physiotherapy: Once pain and swelling decrease, physical therapy exercises can help improve range of motion, strength, and stability in the shoulder joint.
Grade III:
Grade III AC joint separations, which involve complete tearing of the ligaments and significant joint displacement, may require surgical intervention to restore joint alignment and stability.
Surgical options may include AC joint reconstruction or stabilization procedures using hardware such as screws or suture anchors.
After surgery, it is essential rehabilitation helps regain strength, range of motion, and function in the shoulder joint post injury.
Grade IV-VI:
These are severe AC joint separations that involve additional damage to surrounding structures, such as the coracoclavicular ligaments.
Treatment may involve surgical repair of the injured ligaments and reconstruction of the damaged joint structures.
Rehabilitation following surgery is crucial for optimal recovery and functional outcomes.
The choice of treatment depends on various factors, including the patient’s age, activity level, overall health, and the presence of any associated injuries. Your healthcare provider will assess the severity of the AC joint separation and recommend the most appropriate treatment approach based on your individual circumstances.
How can we help?
Here at Lilyfield Physiotherapy, we have experienced physios in sports injuries. If you are unfortunate enough to suffer an acromioclavicular joint injury or shoulder separation, let us help you manage your injury and return safely to your sport. We will guide you through the stages of rehabilitation to help strengthen your shoulder, whilst allowing healing of your injury to occur. It is important to get a correct and accurate diagnosis of your injury to allow the best management plan to be developed, this will reduce the likelihood of complications with your shoulder injury.
