Comparative Study Between Ultrasound Guided Femoral Nerve Block Versus Ultrasound Guided Saphenous Nerve Block After Total Knee Replacement
Authors: Abdelhamid Amr Essam Eldin , Hazem Ashraf Mahmoud , Taeimah Mohamed Osman Awad , Mohamed Ahmed Saoudy Abdelghafour 
Published: October 2021

Abstract

Background
Total knee arthroplasty (TKA) is one of the most commonly performed operations in our daily practice. It is indicated in all patients with severe osteoarthritis and it needs early postoperative ambulation to improve postoperative outcomes and to reduce immobility related complications. Providing adequate analgesic control is very important to achieve functional recovery, facilitates rehabilitation and attenuates the progression from acute to chronic postsurgical pain, aiming to maximize non-opioid analgesics in addition to regional analgesic techniques. It is estimated that the majority of patients experience either severe pain (60% of patients) or moderate pain (30% of patients) following TKA surgeries. With the emergence of enhanced recovery after surgery ERAS clinical pathways, many surgical specialties are adopting multimodal analgesic regimens to improve patient outcomes.

Objective
This study aimed at shedding lights on the value of preserving the motor function in the immediate postoperative period after total knee replacement. That was illustrated by comparing femoral nerve block (mixed motor and sensory nerve) versus saphenous nerve block (pure sensory nerve) in the adductor canal, and the effect of either blocks on the analgesia and ambulation of the patients postoperatively.

Patients and Methods
After approval of the departmental ethical committee, from September 2017 to September 2019, this Prospective double armed interventional randomized clinical study was conducted at Ain Shams University Hospitals, operating theatre department on 40 adult patients of ASA physical status classification I-II, admitted to Ain Shams university hospital, scheduled for elective primary unilateral total knee replacement surgery. The patients were subdivided into 2 groups A and B, (20) patients for each group.

Results
In our study we performed a prospective randomized trial to compare between saphenous nerve block (adductor canal block ACB) versus femoral nerve block FNB regarding postoperative analgesic efficacy in terms of pain scores using visual analogue scale VAS during rest and during 45 degree passive flexion of the knee joint, both were measured at 6, 12, 24 and 48 hours postoperatively. Total nalufen consumption in the first 24 hours postoperative was measured in milligrams. Also postoperative Quadriceps muscle strength clinical testing by using a Timed Up-and-Go test (TUG test) at 24 hours postoperative and (10 minutes walking test) at 24 hours postoperative. We found that analgesic efficacy of both groups in the terms of VAS pain scores and cumulative 1st 24 hours Nalufin consumption are equivalent but there is a statistically significant difference in quadriceps muscle strength being higher in adductor canal block group than femoral nerve block group. TUG test results were lower in ACB group compared to FNB group, and results of 10-minutes walking test were significantly higher in ACB group compared to FNB group. Also incidence of postoperative nausea, vomiting and Sedation was assessed and it was found no statistically significant differences in nausea, vomiting and Sedation between the two groups.

Conclusion
Saphenous nerve block (adductor canal block) is equivalent to femoral nerve block in achieving postoperative pain but it's superior to femoral nerve block in preserving quadriceps muscle power. So it's competent to be chosen as postoperative analgesic modality after Total knee replacement surgeries.