Hip Replacement Pain

Managing hip replacement pain in the post-operative period is an important part of your recovery. There is no such thing as a pain-free operation, and hip and knee surgery prove no exception.

In this blog I will cover some of the more common drugs used in the first days after surgery. A range of drugs are available; how they are used, at what dose and how they are administered are affected by specific operations, individual pain-control requirements, your underlying health, plus also what other medications you take.

Hip replacement pain control actually begins with the operation. Spinal anaesthetics, if appropriate, help with immediate post-operative pain relief. An epidural may also be used. This is similar to a spinal anaesthetic, but a catheter allows for ongoing delivery of analgesia into the epidural space. Local anaesthetic is the most common drug used, but sometimes a small dose of narcotic (such as morphine) is also added to augment pain control. These combine to leaves the limb numb, but able to be moved. Epidurals are usually used for only 1-2 days after surgery.

At the end of the surgery, local anaesthetic can be infiltrated around the site of surgery. This can then be augmented with a pain-pump, which continues to infuse local anaesthetic into the wound for some 24-48 hours.

Some patients have a PCA (Patient Controlled Analgesia), where pain relief is administered through a pump when you press a button. The drug is usually a narcotic, such as morphine or fentanyl. Anti-emetic drugs (to stop vomiting) can be added. Only a set dose of the drug can be delivered over a period of time, preventing too much of the drug being delivered.

One of the benefits of a PCA is you can self-administer the pain-relief shortly before doing something which would otherwise be painful – such as getting out of bed, or physiotherapy. (More about the importance of physiotherapy in a later blog!) A PCA is usually in place for around 24-48 hours. If need, the narcotic will be replaced with an oral tablet, such as endone for short term or breakthrough pain, or a longer-acting opioid such as oxycontin. These are weaned as you improve, and are usually needed only for a short time. The main problems with narcotics are drowsiness (so they can help with sleeping at night), nausea, and constipation.

Paracetamol (panadol) is often seen as a mild analgesic. After all, it’s used in babies. Yet it forms an excellent base on which to add other pain relief.

Paracetamol works mainly by inhibiting the formation of prostaglandins, which are important in both pain and temperature control. This is similar to how NSAIDs work (more below), but the effect is milder, for paracetamol lacks the anti-inflammatory, anti-platelet and gastric erosion effects of the NSAIDs.

Also, paracetamol can be administered through a drip after surgery if you are not eating. Using regular paracetamol helps to reduce the doses and duration of more potent medication.

Other drugs used include the NSAIDs (non-steroidal anti-inflammatory drugs), such as ibuprofen (brufen) and indomethacin. Like paracetamol, they have a variety of methods of action, but work mainly through the inhibition of prostaglandins. Their main limitation is their side effects; many people can get gastric erosions, nausea, or diarrhoea. They can also increase bleeding, and so must be used cautiously if you are on other blood thinners, such as warfarin.

Pain is important; it protects against further injury by limiting use of the painful joint, and acts as a reminder to protect a damaged part of the body. Pain control is equally important, not only for your emotional well-being, but also for recovery, for helping with mobility, and for getting back to that real world which exists outside the hospital.