Effect of dexamethasone added as an adjuvant in Suprainguinal Fascia Iliaca Block (SFİB) application in knee arthroplasty on postoperative pain, analgesic consumption and block characteristics

Aim: Total knee arthroplasty (TKA) is one of the commonly performed orthopedic surgical procedures and typically leads to intense postoperative pain. Therefore, regional anesthesia techniques, including suprainguinal fascia iliaca block (SFIB), have become indispensable in pain management, alongside intravenous, neuroaxial, and infiltrative techniques. Adjuvants are used to enhance the effectiveness or prolong the duration of regional anesthesia techniques, and dexamethasone is one of these adjuvants. In this study, we aimed to compare the postoperative analgesic requirements of patients undergoing TKA with SFIB using a mixture of local anesthetic and adding dexamethasone as an adjuvant. Additionally, we aimed to measure and compare pain scores, block durations, characteristics of motor and sensory blocks, and quality of recovery in these two groups. Method: This study was a prospective, randomized, controlled, and double-blind study conducted at a tertiary university hospital. Patients aged 18-75 years with American Society of Anesthesiologists (ASA) class I-III scheduled for total knee arthroplasty (TKA) were included in the study. Blocks were performed at the end of the surgery in both groups. Patients were divided into two groups based on the local anesthetic used: Group I (0.25% bupivacaine, 50 ml) and Group II (0.25% bupivacaine + 8 mg dexamethasone, 50 ml). Opioid (morphine) requirement in patient-controlled analgesia was recorded throughout the follow-up period, and patients' pain intensity was measured using the numerical rating scale (NRS). The primary outcome assessed was the 24-hour cumulative opioid consumption. Secondary outcomes included NRS scores at 24 hours postoperatively, time to first opioid requirement, presence of quadriceps muscle motor block, as well as the presence of nausea, vomiting, quality of recovery score (QoR-15), and the Timed Up and Go (TUG) test. Results: The study included a total of 80 patients, with 59 females and 21 males (Group I: 40, Group II: 40). Demographic characteristics, including age, gender, body mass index, and ASA classification, were similar between the groups (p>0.05). There was no statistically significant difference in Numeric Rating Scale (NRS) values during both rest and movement postoperatively between the two groups (p>0.01). However, it was found that the time to first analgesic requirement was prolonged in Group II, and the 24-hour cumulative opioid consumption was lower (p<0.05). Quadriceps muscle weakness was identified as negative in all patients at 24 hours postoperatively, and remained at similar levels during the initial 24-hour follow-up in both groups (p>0.05). Side effects such as nausea and vomiting were similar in both groups (p>0.05). The 3-meter walking test performed at 24 hours was shorter in Group I (p<0.05). Results of the QoR-15 questionnaire administered at 24 hours postoperatively were similar in both groups, and the outcomes were reported as good by the patients (p>0.05). Conclusion: In this prospective, randomized study, we determined that the addition of dexamethasone to suprainguinal fascia iliaca block (SFIB) applied postoperatively in patients undergoing total knee arthroplasty (TKA) under spinal anesthesia reduced opioid requirements and delayed the time to first analgesic consumption compared to the group without the added adjuvant. However, other postoperative parameters were similar between the two groups. Further studies conducted in homogeneous groups will be necessary to evaluate SFIB in TKA in terms of volume, concentration, and combined regional techniques.