Anaesthesia for lower limb joint replacement can be approached a number of different ways. The commonest anaesthesia provided for these procedures is a spinal anaesthetic, combined with either a general anaesthetic or sedation (depending on a number of factors including patient preference and coexisting medical conditions). Different levels of monitoring are also required depending on the expected duration & complexity of surgery, and co-existing medical conditions.
Importantly, you will not be required to have any procedure or form of anaesthesia that you are not comfortable with. It is generally useful to have a full discussion of the type of anaesthesia that would suit you best at the time of the preoperative consultation, and to remain open-minded about what approach is best for this particular type of surgery. Many patients are hesitant to have spinal anaesthesia, however after a discussion of the conduct, expectations, and experience of spinal anaesthesia combined with sedation or general anaesthesia they can be reassured of the benefits of this approach. General anaesthesia, (without any supplemental spinal anaesthesia) is also an option for this type of surgery.
Spinal anaesthesia is, generally speaking, a safe and popular form of anaesthesia for many lower limb procedures. It offers profound anaesthesia and pain relief along with other medical advantages – but as with all medical procedures, comes with risks which must be considered prior to selecting this form of anaesthesia for a procedure. Broadly speaking, these advantages and risks are outlined below;
- Good quality pain relief in the immediate post-operative period
- Smoother emergence (wake-up) from surgery
- Likely reduction in nausea and vomiting post-operatively
- There is some evidence that spinal anaesthesia reduces both blood loss during surgery, and the risk of deep venous thrombosis (venous blood clots in the lower limbs) after surgery; however, these benefits are less certain and therefore less significant.
- The risk that concerns most patients to the greatest extent is nerve damage. Serious nerve damage from spinal anaesthesia is exceedingly rare. Most large studies conducted into the use of spinal anaesthesia have placed the incidence of any form of nerve damage at around 1:30,000 or less. Many of these studies involve practices that are no longer in use, and thus the real risk of serious neurological injury is probably overestimated by these figures.
- There is a risk of “post-dural puncture headache” which is a headache with very specific qualities that can require ongoing treatment. This complications usually occurs in younger patients having spinal anaesthesia and is very uncommon in older patient groups who normally present for joint replacements.
- Spinal anaesthesia can have other effects during surgery (such as a lowering of blood pressure). These are usually managed quite routinely during surgery without any adverse sequelae.
Lower limb joint replacements can also be conducted under general anaesthesia (alone) without the addition of spinal anaesthesia. This means that the pain relief used is a combination of intravenous drugs, and local anaesthesia injected by the surgeon around the joint as the operation proceeds. Anaesthesia conducted in this way tends to require greater amounts of pain relief in the immediate post-operative period. The risks and benefits are broadly summarized below.
- Avoidance of any risk associated with regional anaesthesia
- Can be more suitable for patients with specific medical conditions
- Pain relief can be more problematic after emergence compared with spinal anaesthesia
- Post-operative nausea and vomiting is more likely
- Dental damage from insertion of airway equipment
- Other risks of general anaesthesia include complications involving the heart, lungs, or central nervous system. The nature and likelihood of these complications is highly depending on many different factors, including patient health.
Post-operative pain relief
After surgery, you will receive post-operative pain relief that is specific to the type of surgery and anaesthesia you have had, and which takes into account specific characteristics of your medical history & other factors. Generally speaking, knee replacements require a greater amount of pain relief than hip replacements.
Knee replacement patients will usually be provided with a “PCA” (patient controlled analgesia). This is a system whereby the patient can press a button and deliver themselves a small amount of pain relief , before the device locks for a few minutes in order for the pain relief to work. This enables the patient to have some control over the pain relief that they require. This is combined with other types of pain relief (tablets, and other injections) some of which will be given to the patient regularly, & some of which are available to patients if their “background” regime of pain relief isn’t providing enough comfort.