The effect of surgery, in contrary to critical illness, on muscle weakness hasn't been thoroughly investigated. Recent data suggest that elective surgery may also induce muscle weakness. The neuro-endocrine stress response could be involved in the pathophysiology. Whether the mode of anesthesia/analgesia can influence muscle weakness, by influencing the neuro-endocrine stress response is unknown. Gaining insight in this matter could affect quality of care and benefit patient recovery and satisfaction.

In this study, the investigators want to demonstrate whether the application of neuraxial anesthesia for elective surgery diminishes perioperative muscle weakness. Since spinal and epidural anesthesia/analgesia have been shown to influence the neuro-endocrine stress response, the possible underlying mediator of perioperative muscle weakness, the investigators will perform two different, but complementary, studies. In one study, patients scheduled for elective total hip arthroplasty will receive spinal anesthesia, without losing consciousness and maintaining a free airway, as compared to receiving general anesthesia. In another study, patients scheduled for a laparoscopic hemicolectomy will receive epidural anesthesia/analgesia during and after the surgery as compared to receiving no epidural anesthesia/analgesia. These studies allow the investigators to identify whether the application of neuraxial anesthesia/analgesia could diminish perioperative weakness and allow us to identify other possible mediators of perioperative muscle weakness, such as losing consciousness or receiving neuromuscular blockade.

This study has the potential to help to identify a new side-effect of elective surgery, namely perioperative muscle weakness, and to identify a possible treatment for this possible new complication, namely neuraxial anesthesia and analgesia, which might benefit many patients in the future. Furthermore, investigating the possible mediating role of the neuro-endocrine stress response might identify new therapeutic targets, such as glucagon modulation.

Inclusion Criteria:

• Aged 18 years or older.
• Scheduled for elective total hip arthroplasty or hemicolectomy.

Exclusion Criteria:

• Lack of informed consent or inability to give informed consent.

• Urgent surgery, such as hip fracture.

• Contra-indications for spinal or epidural analgesia, including but not limited to:

  • Infection at the site of puncture.
  • Coagulopathy.
  • Severe hypovolemia.
  • Severe aortic valve stenosis (cross sectional area < 1,3 cm2).
  • Severe mitralis valve stenosis (cross sectional area < 1,0 cm2).
  • Increased intracranial pressure.
  • Pre-existing neurological condition.
  • Severe spine deformity.
  • Sepsis.
  • Body mass index (BMI) > 35 kg/m2

• Hypersensitivity or known allergic reactions to any products used for anesthesia.

• History of chronic opioid analgesics use.

• Preoperative use of steroids:

  • Including, but not limited to: injection of hydrocortisone < 3 months before surgery.

• Preexisting muscle disease

  • Including, but not limited to: Steinert's disease, amyotrophic lateral sclerosis (ALS), Duchenne dystrophy, amputation of dominant arm or hand.

Patients will be randomized using a computer-generated permuted block randomization sequence (variable block-size, 1:1 allocation). The randomization will be determined on the preoperative anesthesia assessment. After the randomisation, the investigator will inform the patient which anesthesia he/she will get during the operation