Effect of NMBA on Surgical Conditions in THR

Effect of Neuromuscular Blockade on Surgical Conditions and Patient Reported Comfort Scores in Total Hip Replacement Arthroplasty

During Total hip replacement arthroplasty (THA), the hip joint first must be luxated in order to have access to the joints. A lot of force and torque must be carried out on the joint to perform this manipulation. This is both difficult for the surgeon and may cause additional tissue damage and postoperative pain. After placement of the prosthesis and reduction of the joint, the tension of the hip joint must be evaluated by the surgeon to ascertain the adequacy of the prosthesis. During luxation, minimal muscle tension would be ideal, while after reduction of the joint, normal muscle tension is desired to permit assessment of the mechanics of the hip joint. The aim of the study is to investigate whether deep neuromuscular block, combined with a reversal before mechanics assessment improves surgical conditions, surgical time, and postoperative patient comfort.

2X20 patients are randomised: Rocuronium-group (R-group) and Placebo-group (P-group). All patients receive standardised multimodal intravenous analgesia. After standardised induction of anasthesia and patient positioning, the patient is administered either placebo or rocuronium 0.9 mg/kg, followed by continuous infusion of either placebo or rocuronium 0.4 mg/kg/h. 1 minute before reduction of the hip joint, the patient is administered either sugammadex (R-group) or placebo (P-group) for full reversal of the neuromuscular block. During the surgery, time points are recorded for: incision, start luxation of the joint, start reduction of the joint, start skin closure. The surgeon is blinded for patient allocation. At three moments (after luxation, just before reduction of the joint, and after assessment of joint mechanics), the surgeon is asked to appraise the surgical conditions on an analogue scale. Postoperative analgesic consumption and pain scores are recorded. VAS scores for knee pain and hip pain are assessed before surgery, at the moment of discharge from the post-anesthesia care unit (=D0), the morning after surgery (=D1), at D2, and at D7.

The syringes are prepared by the research assistant who was not involved in patient management. The anesthetist and surgeon are blinded for patient allocation.

Placebo is administered as alternative to rocuronium in a bolus and in a syringe pump. Placebo is administered as alternative to sugammadex

Inclusion Criteria: signed informed consent eligible for primary THA BMI <35 Exclusion Criteria: neurological or psychiatric disorders intolerance or allergy against investigational drugs or any of the drugs used in the standardized analgetics scheme (acetaminophen, diclofenac, ketamine, clonidine, lidocaine)