Hip osteoarthritis is a disease that causes pain and restricts the range of motion as the hip joint deforms. In Japan, the prevalence of hip osteoarthritis is estimated at 1.0%–4.3%, and the number of patients with hip osteoarthritis reaches 1.2–5.1 million . The treatment options for patients with hip osteoarthritis include conservative therapies and surgery. Conservative therapies include patient education, hyperthermia treatment, pharmacological treatment using non-steroidal anti-inflammatory drugs, and physical therapy treatment tailored to the patient’s condition. Surgery is recommended for patients whose condition does not improve with conservative therapies or those in advanced disease stages. Recently, total hip replacement (THA) has been widely performed, with approximately 23,000 THA surgeries being done every year in Japan .
THA causes moderate to severe postoperative pain, and inadequate perioperative analgesia management delays ambulation and decreases the quality of postoperative recovery . Opioids are commonly used for postoperative analgesia in various surgeries, but their use is associated with postoperative nausea and vomiting (PONV) and impaired quality of recovery. Therefore, regional anesthesia is often preferred.
Regional anesthesia for THA includes epidural anesthesia and peripheral nerve blocks. Although epidural anesthesia has been used for postoperative pain management in THA, it has become restricted as perioperative antithrombotic drugs are generally used for orthopedic patients. Currently, many types of peripheral nerve blocks, such as the femoral nerve block (FNB) and the lumbar plexus block (LPB), are used for THA surgeries. The efficacy of FNB for THA has been reported in many studies in the past few decades [4,5]. However, it has been suggested that FNB might not provide sufficient postoperative analgesia for THA because the hip joint is innervated not only by the femoral nerve but also by other nerves such as the obturator nerve and the sciatic nerve. LPB is a procedure during which a local anesthetic is administered around the lumbar nerve roots so that the femoral nerve, obturator nerve, and lateral femoral cutaneous nerve are blocked. Although LPB provides adequate postoperative analgesia for THA , it has a high potential of serious complications such as nerve injury and hematoma , because the needle tip should be advanced close to the nerves.
The quadratus lumborum block (QLB), first reported by Blanco in 2007, is a compartment block procedure during which a local anesthetic is injected into the muscle plane of the quadratus lumborum muscle under ultrasound guidance . Currently, QLB is divided into four types based on the injection point of the local anesthetic: lateral, anterior, posterior, and intramuscular QLB. QLB is widely used for various types of abdominal surgeries . In the anterior QLB, described by Børglum et al. in 2013, a local anesthetic is injected between the quadratus lumborum muscle and the psoas major muscle . Although anterior QLB was first reported for analgesia in abdominal surgeries, it could provide analgesia for lower limb surgeries by spreading the local anesthetic around the psoas major muscle and blocking lumbar nerve roots such as in LPB. Cadaveric studies showed the spread of a dye around the lumbar plexus by anterior QLB [11, 12]. Anterior QLB may block not only the femoral nerve but also the obturator nerve and the lateral femoral cutaneous nerve, thus possibly providing more effective analgesia in THA than FNB. Additionally, because the needle tip is distant from the lumbar nerve roots in anterior QLB, it has lower risk of nerve injury than LPB.
The efficacy of anterior QLB for lower limb surgeries has been reported in some case reports [13–15], but no randomized controlled trials have been conducted. Therefore, it remains unclear whether anterior QLB provides sufficient analgesia and improves the quality of postoperative recovery after lower limb surgeries such as THA.
The aim of this single-center, double-blinded, randomized controlled trial is to confirm the efficacy of anterior QLB for postoperative recovery after THA. Here, we describe the study protocol for such a trial.