Comparative analysis of dual versus single subsartorial block for postoperative analgesia after total knee arthroplasty - A randomized, double-blind study.

Background and aims: This study compared the dual sub-sartorial block (DSB), which allegedly includes all pain generators of the anterior and posterior compartments of the knee joint, to the routinely used single sub-sartorial bock (SSB), in terms of analgesic efficacy and preservation of motor strength after unilateral total knee arthroplasty (TKA).

Material and methods: Sixty patients aged 18-80 years and ASA grade I-III undergoing unilateral TKA were randomised to two groups postoperatively to receive DSB or SSB. Patients in group DSB received distal femoral triangle block (15 ml) + proximal adductor canal block (20 ml), while group SSB received only proximal adductor canal block (20 ml). Primarily, the changes in pain intensity and pain control in terms of static and dynamic visual analogue score (VAS) with the duration of analgesia and cumulative dose requirement of rescue analgesic in the first 24 hours postoperatively were studied. Secondary outcomes were the postoperative degree of motor blockade, the ability of early ambulation, patient satisfaction and complications. Statistical analysis was done using the student t-test and Chi-square test using MedCalc version 12.4.3.0.

Result: At all time intervals, the static and dynamic VAS scores were lower in the patients with the DSB group (P < 0.001) with longer duration of postoperative analgesia (14.96 ± 5.05 vs 6.03 ± 1.73 hours, P < 0.0001) and less requirement of total parenteral analgesic (1.06 ± 0.37 vs 2 ± 0.52, P < 0.0001) in first 24 hours postoperatively. A shorter time was required to finish the Timed Up and Go test for patients belonging to the DSB group (53.48 ± 4.06 vs 66.16 ± 6.23 seconds, P < 0.0001) in comparison to group SSB.

Conclusion: DSB provided better pain control with a longer duration of analgesia and required fewer doses of parenteral analgesics in the first 24 hours postoperatively after TKA, as opposed to SSB. Neither block had incidences of motor weakness and other complications.