Analgesic benefits of single-shot versus continuous adductor canal block for total knee arthroplasty; systematic review

Background: Postoperative pain after total knee arthroplasty (TKA) delay mobilization and rehabilitation. Adductor canal block (ACB) is widely used because it provides analgesia while preserving quadriceps strength, but it’s uncertain whether single-shot Adductor canal block (SACB) or continuous Adductor canal block (CACB) had the better postoperative outcomes. This review evaluated their effects on pain, opioid consumption, and early functional recovery after TKA. Methods: This systematic review followed PRISMA guidance. MEDLINE, Scopus, Web of Science, Embase, and the Cochrane Central Register of Controlled Trials were searched from inception to 2025 for original studies comparing SACB with CACB in TKA. Two reviewers screened studies, and assessed full texts. We found heterogeneity in study design, block protocols, and outcome reporting, so the findings were analyzed qualitatively rather and meta-analysis not done. Results: We initially identified 172 records, 106 were screened, 28 full texts were assessed, and 9 studies involving 1,307 patients were included. CACB provided more steady analgesic benefit than SACB, especially after 12 to 24 hours, with several studies showing lower pain scores at 24 and 48 hours, and reduced opioid use. Some trials found equivalent early analgesia, mainly when SACB was combined with adjuvants or multimodal analgesia. Functional outcomes were mixed, with some studies favoring CACB for ambulation or range of motion and others showing no significant differences. Conclusion: CACB provide more sustained analgesia and opioid-sparing benefit after TKA, whereas functional advantage over SACB still not confirmed and context dependent.