Anaesthetic Risks — GA, Spinal and Nerve Blocks

Part of The Joint Replacement Guide — Phase 3: Understanding the Risks · Article 13 of 42 · Hip & Knee

Key Points

  • Most hip and knee replacements can be performed under general anaesthesia, spinal (regional) anaesthesia, or a combination of the two.
  • Spinal anaesthesia is often preferred for joint replacement, with evidence suggesting fewer complications for this type of surgery.
  • Nerve blocks provide targeted pain relief around the joint and reduce how much strong painkiller you need afterwards.
  • Your anaesthetist will discuss which option suits you individually, taking your health and preferences into account.

General Anaesthesia

A general anaesthetic (GA) puts you fully to sleep for the operation, with your breathing supported by the anaesthetic team throughout. It is very safe for the vast majority of patients, though common minor side effects include nausea, a sore throat, and feeling groggy for a period afterwards. More serious complications from general anaesthesia are rare, and your anaesthetist will assess your individual risk factors as part of pre-operative assessment.

Spinal (Regional) Anaesthesia

A spinal anaesthetic involves an injection in the lower back that numbs the lower half of the body, while you remain awake or lightly sedated for the operation. For hip and knee replacement specifically, spinal anaesthesia is often the preferred option, with evidence suggesting it is associated with reduced blood loss, a lower risk of blood clots, less post-operative nausea, and in some studies, a faster early recovery compared with general anaesthesia alone. This preference is reflected in many modern Enhanced Recovery After Surgery (ERAS) protocols, although the final choice always depends on your individual health, anatomy, and personal preference.

Nerve Blocks

A nerve block involves injecting local anaesthetic around specific nerves supplying the operated joint — for example, around the femoral or adductor canal nerves for a knee replacement, or the fascia iliaca compartment for a hip replacement — providing several hours of targeted pain relief as the effect wears off gradually. This is a key part of modern multimodal pain management, reducing how much strong (opioid) painkiller you need in the first day or two after surgery, which in turn helps with earlier, more comfortable mobilisation.

Choosing What’s Right for You

The right combination for you depends on factors including your general health, any previous spinal surgery (which can occasionally make a spinal anaesthetic more difficult or unsuitable), and your own preference. This will be discussed in detail at your pre-assessment appointment and again with your anaesthetist on the day of surgery, and you are entitled to ask questions and express a preference as part of that conversation.

In More Depth

Much of the strongest evidence favouring regional over general anaesthesia comes from research in hip fracture surgery, where the case for reduced complications and mortality is well established; the evidence in elective hip and knee replacement is generally supportive of similar benefits but the differences are more modest, and both approaches are considered safe and appropriate. In practice, many modern joint replacement pathways combine techniques — for example, a spinal anaesthetic with light sedation, plus a nerve block for post-operative pain relief, or occasionally a general anaesthetic combined with a nerve block where a spinal isn’t suitable. This combined, multimodal approach reflects current best practice more than any single technique in isolation.

This article is general information and does not replace individual clinical advice. Your anaesthetic plan will be discussed and agreed with you individually.

Sources

  • Royal College of Anaesthetists — patient information on anaesthesia for joint replacement
  • Association of Anaesthetists — regional anaesthesia guidance
  • ERAS Society — Enhanced Recovery After Surgery guidelines
  • NICE guideline NG157 — Joint replacement (primary): hip, knee and shoulder (2020)

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