Contribution of Multimodal Analgesia to Postoperative Pain Outcomes Immediately After Primary Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis of Level 1 Randomized Clinical Trials

Background: Anterior cruciate ligament reconstruction (ACLR) is associated with moderate to severe pain in the immediate postoperative period. The optimal individual preemptive or intraoperative anesthetic modality on postoperative pain control is not well-known. Purpose: To systematically review and perform a meta-analysis comparing postoperative pain scores (visual analog scale [VAS]), opioid consumption, and incidence of complications during the first 24 hours after primary ACLR in patients receiving spinal anesthetic, adjunct regional nerve blocks, or local analgesics. Study Design: Systematic review and meta-analysis. Methods: PubMed, Embase, MEDLINE, Biosis Previews, SPORTDiscus, Ovid, PEDRO, and the Cochrane Library databases were systematically searched from inception to March 2020 for human studies, using a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) checklist. Inclusion criteria consisted of (1) level 1 studies reporting on the use of spinal anesthesia, adjunct regional anesthesia (femoral nerve block [FNB] or adductor canal block [ACB]), or local analgesia in patients undergoing primary ACLR and (2) studies reporting on patient-reported VAS, opioid consumption, and incidence of complications related to anesthesia within the first 24 hours after surgery. Non–level 1 studies, studies utilizing a combination of anesthetic modalities, and those not reporting outcomes during the first 24 hours were excluded. Data were synthesized, and a random effects meta-analysis was performed to determine postoperative pain, opioid use, and complications based on anesthetic modality at multiple time points (0-4, 4-8, 8-12, 12-24 hours). Results: A total of 263 studies were screened, of which 27 level 1 studies (n = 16 regional blocks; n = 12 local; n = 4 spinal) met the inclusion criteria and were included in the meta-analysis. VAS scores were significantly lower in patients receiving a regional block as compared with spinal anesthesia 8 to 12 hours after surgery (P <.01), patients receiving an FNB versus ACB at 12 to 24 hours (P <.01), and those treated with a continuous FNB rather than single-shot regional blocks (FNB, ACB) at 12 to 24 hours (P <.01). No significant difference in VAS was appreciated when spinal, regional, and local anesthesia groups were compared. Conclusion: Based on evidence from level 1 studies, pain control after primary ACLR based on VAS was significantly improved at 8 to 12 hours in patients receiving regional anesthesia as compared with spinal anesthesia. Pain scores were significantly lower at 12 to 24 hours in patients receiving FNB versus ACB and those treated with continuous FNB rather than single-shot regional anesthetic.