Femoral nerve inguinal approach versus proximal femoral triangle ap proach for continuous regional analgesia in active rehabilitation after total knee arthroplasty: A prospective, randomised study

Background: A catheter in femoral nerve block (F-Cath) is an effective regional analgesia technique in total knee arthroplasty (TKA) but results in significant quadriceps weakness. The femoral triangle catheter (FTB-Cath) seems to be an interesting alternative. In this study, we aim to demonstrate that the nerve block administration for analgesic purposes via an FTB-Cath results in less quadriceps weakness than via an F-Cath.

Methods: This study included patients scheduled for TKA performed under general anaesthesia. The patients were randomised to receive either an F-Cath or an FTB-Cath. A unique regimen of 0.2% ropivacaine was administrated for 72 h. The primary endpoint was quadriceps strength assessed clinically on postoperative day (POD) 2 by the Manual Muscle Test (MMT) using a motor grading scores (0-5). The secondary endpoints were quadriceps strength measured by a dynamometer, the Timed Up and Go (TUG) test, the 30-m walk test (30MWT) and pain scores.

Results: Forty-four patients were analysed (22 in each group). On POD 2, 77.3% of the patients in the FTB-Cath group had MMT scores ≥ 4 and 13.6% in the F-Cath group (p < 0.001). During the first four POD assessments, quadriceps strength evaluated with a dynamometer was less diminished in the FTB-Cath group (p < 0,001). There was no difference between groups regarding pain scores, TUG test results and 30MWT assessment.

Conclusion: The FTB-Cath provided a better preservation of quadriceps strength than the F-Cath in TKA, with a similar pain relief.