AC Joint Injections: Procedure, Benefits, Risks, and Rehabilitation

How to inject an AC joint?

AC joint injections are precise medical procedures aimed at alleviating pain and inflammation in the acromioclavicular joint, exclusively performed by licensed healthcare professionals such as orthopedic surgeons, sports medicine physicians, or interventional radiologists, often guided by imaging.

Understanding AC Joint Injections: A Medical Procedure

The acromioclavicular (AC) joint, located at the top of the shoulder where the clavicle (collarbone) meets the acromion (part of the shoulder blade), is crucial for shoulder mobility and stability. When this joint becomes inflamed or degenerated due to injury, overuse, or arthritis, it can cause significant pain and limit function. An AC joint injection is a common medical intervention designed to address these issues.

What is an AC Joint Injection? An AC joint injection involves the precise delivery of medication directly into the acromioclavicular joint space. The substances typically injected include:

• Corticosteroids: Powerful anti-inflammatory medications that reduce swelling and pain. Their effects are usually temporary, providing relief for weeks to months.
• Local Anesthetic: Often combined with corticosteroids, this provides immediate pain relief, which can also serve a diagnostic purpose by temporarily numbing the specific pain source.

Who Performs AC Joint Injections? It is critical to understand that AC joint injections are complex medical procedures requiring specialized training, anatomical knowledge, and sterile technique. They are exclusively performed by licensed healthcare professionals, including:

• Orthopedic Surgeons
• Sports Medicine Physicians
• Pain Management Specialists
• Interventional Radiologists

Fitness professionals, kinesiologists, or individuals without medical licensure are not authorized nor trained to perform injections. Attempting to do so is dangerous, illegal, and can lead to severe complications.

Why Are AC Joint Injections Performed? AC joint injections serve both therapeutic and diagnostic purposes:

• Pain Relief: To alleviate chronic or acute pain stemming from AC joint arthritis, osteoarthritis, post-traumatic arthritis, or inflammatory conditions like synovitis.
• Inflammation Reduction: To decrease inflammation within the joint capsule, which contributes to pain and stiffness.
• Diagnostic Tool: If the injection provides significant temporary pain relief, it helps confirm that the AC joint is indeed the primary source of the patient's shoulder pain.
• Facilitate Rehabilitation: By reducing pain, the injection can create a window of opportunity for the patient to more effectively engage in physical therapy and rehabilitation exercises, which are crucial for long-term recovery and function.

The Patient's Experience: What to Expect During an AC Joint Injection

For individuals experiencing AC joint pain, understanding the process of an injection can help alleviate anxiety and prepare them for the procedure.

Before the Procedure

• Consultation and Assessment: A thorough medical history, physical examination, and review of imaging (X-rays, MRI) will be conducted by the physician to confirm the diagnosis and determine if an injection is appropriate.
• Medication Review: Inform your doctor about all medications you are taking, especially blood thinners, as these may need to be temporarily adjusted.
• Allergies: Discuss any known allergies, particularly to anesthetics or contrast dyes.

During the Procedure

• Positioning: The patient is typically seated or lying down, allowing the physician clear access to the AC joint.
• Sterile Preparation: The skin over the injection site is thoroughly cleaned with an antiseptic solution to minimize the risk of infection.
• Local Anesthetic (Optional): A small amount of local anesthetic may be injected into the skin and surrounding tissues to numb the area, making the procedure more comfortable.
• Imaging Guidance: To ensure precise placement of the needle and medication, the procedure is often performed under imaging guidance, such as:
  • Ultrasound Guidance: Real-time visualization of the needle entering the joint capsule.
  • Fluoroscopy (X-ray Guidance): Live X-ray imaging, sometimes with a small amount of contrast dye, to confirm needle position.
• Needle Insertion and Medication Delivery: Once the needle is accurately positioned within the AC joint space, the corticosteroid and/or local anesthetic mixture is slowly injected. Patients may feel a sensation of pressure or a brief, dull ache during this step.

After the Procedure

• Immediate Care: A small bandage is applied to the injection site. Patients are usually monitored briefly before being discharged.
• Activity Restrictions: Patients are typically advised to avoid strenuous activity, heavy lifting, or direct pressure on the shoulder for 24-48 hours to allow the medication to settle and reduce the risk of post-injection flare-up.
• Pain Management: It's common to experience a temporary increase in pain for the first 24-48 hours as the local anesthetic wears off and before the corticosteroid takes full effect. Ice packs can help manage this.
• Monitoring for Complications: Patients are advised to watch for signs of infection (increased redness, swelling, warmth, fever) or other adverse reactions and to contact their doctor if these occur.
• Follow-up: A follow-up appointment is often scheduled to assess the effectiveness of the injection and plan the next steps, which frequently involve physical therapy.

The Role of Exercise Science and Rehabilitation

While injections offer symptomatic relief, they are rarely a standalone solution for long-term AC joint health. Exercise science and targeted rehabilitation play a pivotal role in optimizing outcomes and preventing recurrence.

Pre-Injection Management Before considering an injection, conservative management is often the first line of defense. This typically involves:

• Rest and Activity Modification: Avoiding activities that aggravate the joint.
• Ice and Heat Therapy: To manage pain and inflammation.
• Oral Medications: NSAIDs (non-steroidal anti-inflammatory drugs) to reduce pain and inflammation.
• Physical Therapy: A structured program focusing on:
  • Pain-free range of motion exercises.
  • Scapular stabilization exercises: Strengthening muscles that control the shoulder blade (e.g., serratus anterior, rhomboids, lower trapezius).
  • Rotator cuff strengthening: To improve overall shoulder stability and mechanics.
  • Postural correction: Addressing any biomechanical imbalances that might contribute to AC joint stress.

Post-Injection Rehabilitation Once the pain relief from an injection takes effect, it provides a crucial window to maximize the benefits of rehabilitation. The focus shifts to:

• Gradual Return to Activity: Progressing from gentle movements to more complex and load-bearing exercises as pain allows.
• Targeted Strengthening: Continuing to build strength in the surrounding shoulder girdle muscles to improve joint stability and reduce stress on the AC joint. This includes:
  • Deltoid and upper trapezius strengthening (cautiously, as these can sometimes aggravate the AC joint if not done correctly).
  • Pectoralis major and minor stretching to prevent anterior shoulder tightness.
• Mobility and Flexibility: Maintaining or improving the overall range of motion of the shoulder complex.
• Proprioception and Neuromuscular Control: Exercises that improve the body's awareness of the joint's position in space, enhancing stability.
• Functional Movement Patterns: Reintegrating sport-specific or activity-specific movements in a controlled and progressive manner.

Importance of a Multidisciplinary Approach Effective management of AC joint pain often requires collaboration between medical professionals (who perform injections) and exercise science professionals (like kinesiologists or physical therapists). This ensures that the patient receives both medical intervention for acute symptoms and a comprehensive rehabilitation plan for long-term recovery and prevention.

Potential Risks and Considerations

While AC joint injections are generally safe, like any medical procedure, they carry potential risks.

Common Risks

• Post-Injection Flare: Temporary increase in pain, swelling, or redness at the injection site, usually resolving within 24-48 hours.
• Infection: Though rare with sterile technique, there's a small risk of bacterial infection at the injection site or within the joint.
• Bruising or Bleeding: At the injection site.
• Nerve Damage: Extremely rare, but possible if a nerve is inadvertently punctured or irritated.
• Allergic Reaction: To the anesthetic or corticosteroid.
• Skin Discoloration or Fat Atrophy: Rare, but corticosteroids can sometimes cause lightening of the skin or thinning of the subcutaneous fat at the injection site.

Contraindications

• Active Infection: In the joint, surrounding skin, or elsewhere in the body.
• Bleeding Disorders or Anticoagulant Use: May increase the risk of bleeding.
• Uncontrolled Diabetes: Corticosteroids can temporarily elevate blood sugar levels.

When to Seek Professional Medical Advice

If you are experiencing pain or discomfort in your AC joint or shoulder, it is imperative to seek evaluation from a qualified medical professional. They can accurately diagnose the cause of your pain and recommend the most appropriate course of treatment, which may or may not include an AC joint injection. Self-diagnosing or attempting to treat such conditions without professional medical guidance can lead to improper management, delayed recovery, and potentially more serious complications.