adductor canal vs adductor canal plus spank block for postoperative pain in knee arthroplasty surgery

Conditions: Arthroplasty, Replacement, Knee; Anesthesia, Conduction; Acute Pain

Summary: this study will prospectively investigate the efficacy of adductor canal block with periarticular infiltration vs adductor canal block, periarticluar infiltration and sensory posterior articular nerve of the knee block in patients undergoing total knee arthroplasty. the study will aid in answering question whether spank block is an effective adjunct in preventing posterior knee pain without causing motor blockade.

total knee arthroplasty (tka)is a common orthopedic surgical procedure. optimal pain control is necessary for early recovery and discharge. tka is considered one of the more painful surgical procedures, peripheral nerve blocks and multimodal analgesia are incorporated into clinical practice to provide patient comfort, decrease postoperative opioid requirement, facilitate early ambulation and enhance patient satisfaction.adductor canal nerve block (acb) and intraoperative periarticular infiltration (pai) are routine clinical practice followed at our institute for postoperative pain control. although acb provided analgesia to peripatellar and anterior intra-articular aspect of knee joint, it does not relieve posterior knee pain which can be moderate to severe in intensity. many techniques have been employed for posterior knee pain including sciatic nerve block and infiltration between popliteal artery and posterior capsule of the knee joint (ipack) with limited success. sciatic nerve block is considered gold standard but is rarely used due to associated motor weakness, which may delay ambulation and decrease participation in physical therapy postoperatively . in recent times ipack block has gained popularity but there are concerns about local anesthetic injection close to surgical field and total dose of local anesthetic exceeding the recommended amount if combined with periarticular infiltration as is the practice at our institute. spank block was described in 2015 by kardash et al for posterior knee pain while sparing motor function. the block is performed at the level of femoral shaft above the femoral epicondyle, on the medial side of the leg, with needle positioned just superficial to posteromedial femoral periosteum and 15 ml of local anesthetic is injected, decreasing concerns for local anesthetic toxicity, and invasiveness close to surgical field as compared to ipack block which requires 30 ml of local anesthetic. efficacy of spank block has been demonstrated as rescue analgesic for posterior knee pain after tka, and a trial is underway to evaluate efficacy of acb an spank block versus acb alone \[5\].there is no literature evaluating benefit of spank block when added to acb and pai which is a standard practice. if spank block proves to be effective in controlling posterior knee pain, with motor sparing effect it can help reduce postoperative opioid requirement, help achieve same day discharge and prove to be another small step towards fighting opioid epidemic. hence, we propose this study to evaluate added benefit of spank block to acb and pai with regards to postoperative pain control.

Eligibility criteria:
inclusion criteria: patients between the ages of 19 and 90 years old. bmi 18-45 asa class i-ii-iii exclusion criteria: simultaneous bilateral tka. history of substance abuse. bmi \>45. patients that did not received intrathecal anesthesia. infection at the site of injection (either for spinal or pnb). pregnancy. non english speaking or inability to participate in the study. patients with coagulopathy or with inr \>1,5 the day of the surgery. pharmacologic coagulopathy: patients on xarelto, plavix, or any kind of "blood thinners". chronic steroid use: patients with consumption of steroid for more than 3 months. chronic pain: pain for more than 3 months. chronic opiate use : consumption of opioids for more than 3 months.