A clinical deep NMB might relax the anterior muscles of the upper leg better than a moderate/superficial block giving a better exposure for the surgeon with less muscle trauma by traction to expose the hip.

a continuous deep NMB (group A) versus a non deep NMB (group B) having a moderate to superficial block imitating common practice today as control group.

Primary objectives are surgical exposure and Secondary objectives are Muscle damage creatine kinase changes, C-reactive protein (CRP), first time leaving bed postoperative, post operative pain as measured by opioid use postoperative at 24h, with a control of max VAS score during first 24 hour, length of hospital stay (LOS), number of adverse events using the Dindo-Clavien surgical complication score, QoR15 measured at 24h on the ward.

In this study, CRP levels are choosen as it is measured standard in every total hip arthroplasty (THA) procedure. CK is a good biomarker for muscle trauma and therefore chosen as second marker.

The study is blinded for the treating surgeon, who will be making the assessment for the surgical conditions. The attending anesthesiologist is not blinded as he has to measure NMB in both groups and give a rocuronium infusion to stay deep in the study group. The anesthesiologist and the nurses following the patient on the post anesthetic care unit (PACU) and the ward are different from the attending anesthesiologist and are blinded. They will not be informed by the attending anesthesiologist on randomization allocation.

Randomization:

Group A deep NMB group:

• 0,6 mg/kg LBW Rocuronium is used to facilitate intubation, and followed by an infusion of 1 mg/kg LBW/h , further adapted to keep post tetanic count (PTC) < 3 without informing the surgeon of the depth (surgeon is blinded)

Group B moderate to superficial NMB group:

• 0,6 mg/kg LBW rocuronium is used to facilitate intubation, not followed by an infusion or extra bolus.train of four ( TOF) and PTC are measured at the beginning of surgery without informing the surgeon of the depth. (surgeon is blinded)

  2 weeks before surgery at consultation of orthopedics and anesthesia:

• Inclusion criteria, signing informed consent, CRP blood sample

• 15 Quality of recovery questions (QoR15) filled in to have a pre op status

Day before surgery:

• Verification that study can be performed ( equipment, surgeon, anesthesiologist and investigators available) Morning of surgery
• Control signing of informed consent is done and patient still willing to continue the study
• Attending anesthesiologist ask the randomization allocation at the secretary anesthesia without informing surgeon, colleagues and nurses on PACU and ward.

Anesthesia & surgery performed

• CRF is filled in with time stamps, dosing of drugs and monitoring values
• Surgeon is asked for a surgical exposure grading ( 1-5) after initial incision, at the critical moment of prosthesis insertion and before closure.
• In order to measure the degree of muscle damage, one light photo is taken of the muscles before closing and archived for later anonymous scoring by an independent orthopedic surgeon doing also THA by DAA but not around that day in the OR (3 surgeons do frequently THA by DAA).
• If an opioid is given before PACU admission dose and time are noted in the clinical registration file (CRF) PACU
• VAS score is recorded on admission, every hour and before leaving PACU.
• The total dose of opioids given during the PACU are noted in the CRF Ward
• Max visual analog pain score (VAS) during first 24 hours on the ward is noted in the CRF.
• The QoR15 is repeated at 24 hours post surgery
• A CRP blood sample is taken 24 hours post surgery
• The total dose of opioids given on the ward till discharge is noted in the CRF

Home

• 2 weeks after surgery a phone call is given to request healthy state
• and hear of any adverse event or complication.
• and repeat the QoR15 questionnaire by phone

Inclusion Criteria:

• • Hip arthroplasty by anterior approach using Minimally Invasive Surgery

Exclusion Criteria:

• • Revision arthroplasty.

  • Allergy or contra indications to use any of the drugs included in anesthesia.
  • Addiction to or chronic opioid use before surgery.
  • Major cardiovascular, pulmonary, liver or renal insufficiency before surgery requiring possible post-operative intensive care admission.
  • Contra indication for a general anesthesia with intubation and mechanical ventilation.