A new systematic review and meta-analysis compared the analgesic efficacy and functional outcomes of femoral triangle block vs adductor canal block following total knee arthroplasty.

Researchers, led by Shangqin Bai, of the Qinghai University, analyzed six randomized controlled trials (RCT) published between 2020 and 2023, comprising 452 patients equally divided between femoral triangle block (FTB) and adductor canal block (ACB) groups.

Key Findings

The analysis revealed no statistically significant difference in resting and activity pain scores at 6, 12, and 24 hours postoperatively between the two techniques. However, at 48 hours, FTB demonstrated superior analgesic efficacy during activity compared with ACB.

"The analgesic effect of activity at 48 [hours] postoperatively was better in the FTB group than in the ACB group," the study authors reported. 

A notable difference emerged when examining different nerve block methods. 

"The FTB group achieved superior analgesic efficacy after a single block compared with the ACB group after a continuous block, although the analgesic effect of the ACB group outperformed that of the FTB group," the study authors added.

Muscle Function and Patient Outcomes

Three of the included studies concluded that ACB better preserved quadriceps muscle strength, whereas one study suggested that FTB had advantages in quadriceps strength recovery. The study authors noted: 

"The ACB group seemed to have some advantages in the rapid postoperative quadriceps muscle strength recovery."

No statistically significant differences were observed between the groups regarding postoperative adverse reaction incidence rates and patient satisfaction scores.

Implications and Limitations

The investigators acknowledged several study limitations, including the small number of studies, variation in nerve block medication regimens, and a focus on short-term inpatient outcomes without long-term follow-up.

"This study compared the safety and efficacy of ACB and FTB for analgesia post–total knee arthroplasty (TKA)," the study authors stated. "Because of the differences in our enrolled articles, further large-scale, high-quality RCTs should be performed to demonstrate whether the safety and efficacy of ACB are better than FTB following TKA," they continued.

The anatomical distinctions between the two techniques likely contributed to their differential effects on analgesia and muscle function. FTB targets multiple nerve branches, including the saphenous nerve, medial femoral cutaneous nerve, and medial femoral nerve branches, whereas ACB primarily targets the saphenous nerve within the adductor canal.

The new research provided valuable evidence to help clinicians select the most appropriate nerve block technique among patients undergoing TKA, considering both pain control and functional recovery objectives.

Source: BMC Anesthesiology