What Is Periarticular Injection?
Periarticular injections are injections administered around a joint during surgery to help reduce discomfort following the operation. Periarticular injections are also known as local infiltration analgesia or multimodal medication injections. These specialized injections are becoming increasingly common for pain management following major joint replacement surgery, such as a knee or hip replacement. They operate by injecting a mixture of pain medicine into the soft tissues surrounding the surgical site while the procedure occurs.
Periarticular injection refers to injecting medication into the tissues around the joint. The injected medicine mix acts locally to suppress pain signals caused by surgical damage to the joint area. For example, during a total knee replacement, the doctor will inject the medicine mix into the knee cartilage, ligaments, joint capsule, muscle, and fat layers around the joint. The drugs will then work directly where they are injected, preventing pain signals from the surgical cutting and trauma to specific tissues from reaching the brain.
By injecting this combination of pain relieving medication right where the surgery is happening, it blocks the pain at the source and stops it from ever reaching the brain where we register pain. So, patients will have much less pain after the joint surgery compared to not having the periarticular injections. The pain relief starts working as soon as the operation is finished.
What Are the Contents of Periarticular Injection?
The mixture of drugs injected around the joint for periarticular injections is often diluted in salt water to make approximately 100mL total. The key drugs in the mix include:
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Local Anesthetics - These are numbing medicines like Ropivacaine, Bupivacaine, or Levobupivacaine. They function by temporarily preventing the nerves from transmitting pain signals. Local anesthetics are the most essential medications used in injections to relieve pain following surgery.
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Steroid Anti-inflammatory Drugs- Steroids such as Dexamethasone reduce swelling and inflammation, which relieves pain.
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Opioid Painkillers - Morphine and related opioids augment the efficacy of analgesic drugs, resulting in greater pain alleviation.
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Epinephrine- Epinephrine tightens the blood vessels, allowing the numbing medicine to work longer.
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Anti-inflammatory Painkillers- NSAIDs, such as Ketorolac, reduce pain and edema.
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Antibiotics - Antibiotics help prevent infection of the surgical site.
What Is the Mechanism of Action of Periarticular Injection?
Periarticular injections work locally by giving them close to the surgery site, preventing pain signals from reaching the brain. The trauma and damage from the surgery induce nociceptive pain. This means it stimulates pain receptors known as nociceptors, which deliver pain signals to the spinal cord and brain.
The medications used in the periarticular injection work together to suppress pain signals at their source before they reach the central nervous system. The local anesthetic numbs the nociceptors, preventing them from sending pain signals. Anti-inflammatory medicines diminish swelling and inflammation, which stimulates nociceptors. In addition, opioids bind to opioid receptors, which block pain transmission.
Because numerous medications are employed, they can block pain from various pathways more effectively. The injections only affect the operative joint and do not produce numbness or paralysis elsewhere. This differs from nerve blocks, which can cause negative effects by blocking entire nerves that supply sensation and movement to greater areas.
What Is the Technique Involved in Periarticular Injection?
The proper injection technique ensures that drugs are distributed and absorbed optimally. The main steps are:
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Use a tiny, 22 to 25-gauge needle. This allows the fluid to be injected precisely without harming the tissues.
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Instead of a few large doses, make several little injections of 5-10mL each. Small amounts will spread more evenly and prevent leaks into the joint space.
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Inject slowly so that the fluid can pass through the tissue layers. Fast injections can cause the drug to overflow rather than soak in.
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The fluid should visibly lift the periosteum layer covering the bone. This ensures the medication is getting absorbed into the tissues.
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Before injecting near blood vessels, draw back on the syringe to look for blood, which indicates a vessel. Avoid injecting into vessels.
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Inject around pain-sensitive areas such as the periosteum while avoiding blood arteries, nerves, and the joint cavity.
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Before implanting the prosthetic joint, inject the primary sites, such as the thigh bone and the rear of the joint capsule.
What Are the Precautions and Contraindications of Periarticular Injection?
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Periarticular injections should not be administered to patients who are allergic to any of the drugs contained in the injection. This is the sole absolute contraindication.
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Do not inject the needle into blood vessels or cause nerve damage when inserting it. Pull back on the syringe before injecting to ensure that no blood is injected into the vessels. To avoid injury, pay special attention to nerve sites.
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The overall amount of numbing drug used must be within safe limits for the patient's weight. Toxicological effects can occur at excessive doses.
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Periarticular injections are quite safe as long as the patient is not allergic, the injections do not enter blood vessels or nerves, and the anesthetic dose is within limits.
What Is the Future Perspective of Periarticular Injections?
Periarticular injections are a great technique to control pain since they avoid many of the issues associated with other pain treatment methods.
These injections are an important element of the pain-management options available to people without the use of opioids and their associated risks. They help people heal faster and with less discomfort following major joint procedures. Periarticular injections only act locally rather than giving medications through the whole body, so they are cost-effective and safe. They reduce the need for opioid painkillers after surgery as well.
In the future, periarticular injections will likely play a bigger role in pain control for joint replacement surgeries. Advances to optimize the injections will help them reach their full potential. The advantages they offer to patients, such as reduced pain, diminished reliance on opioids, and accelerated recovery, position them as a highly effective pain management alternative.
Conclusion
Periarticular injections are emerging as a pivotal technique for minimizing pain after major joint surgeries. Combined with other analgesics, these localized injections around the surgical site provide effective pain relief, improving patient recovery. Continuous progress in injection formulations and delivery techniques is poised to augment the effectiveness and safety of periarticular injections. By optimizing this injection modality, patients can experience less postoperative pain and opioid requirements. With their simple and low-risk mechanism of targeting pain pathways near the source, periarticular injections have great potential to transform postoperative pain control following orthopedic procedures. Their continued integration into multimodal protocols promises improved outcomes and faster recovery for joint replacement patients.
