Effect of Saphenous Nerve and Nerve to Vastus Medialis Block Within Subsartorial Femoral Triangle on Quadriceps Strength

Effect of Saphenous Nerve and Nerve to Vastus Medialis Block Within Subsartorial Femoral Triangle on Quadriceps Strength

Effect of Ultrasound-guided Saphenous Nerve and Nerve to Vastus Medialis Block Within Subsartorial Femoral Triangle on Quadriceps Strength

This research objective is to compare quadriceps strength by measuring maximal voluntary isometric contraction (MVIC) and risk of fall before and after subsartorial femoral triangle block (SSFTB)

Patients who underwent major knee surgery and had already planned to perform subsartorial femoral triangle block (SSFTB) were included in the study. They were measured the outcomes the night before surgery. The saphenous nerve and nerve to vastus medialis were blocked at the subsartorial femoral triangle level by experienced anesthesiologists. After standard monitor, the distal femoral triangle was identified 2 cm proximal to the opening of adductor canal by ultrasound guidance. At this level, The location of nerve to vastus medialis was confirmed by nerve stimulator and it was blocked with 0.5% levobupivacaine 5 ml. Then, 0.5% levobupivacaine 10 ml would be injected perifemoral artery. The outcomes were re-assessed 30 min after block.

Quadriceps strength will be assessed as MVIC with handheld dynamometer (HHD, Lafayette Instrument, Lafayette, IN).

The muscle power will be graded compared to another leg: 0 = No motor block, 1 = partial motor block, 2 = complete motor block.

If the patient can be able to stand independently for at least 30 seconds without support, he or she will be asked to do functional reach test, which the patient should reach forward by staying put feet. The difference of starting and ending point of the reaching hand will be measured. If the patient cannot stand independently for at least 30 seconds without support or do functional reach test less than 25 cm indicates that he or she has a higher risk for falls.

Inclusion Criteria: Eligible patients are all ASA class I-III, age 18-80 years, and have plan to perform SSFTB at Thammasat University Hospital consecutively Exclusion Criteria: Exclusion criteria are patients who refuse to participate the study, morbid obesity (BMI ≥ 35 kg.m2), lower extremity neurological dysfunction, performing other peripheral nerve blocks, patients who cannot cooperate or measure MVIC, difference of quadriceps strength between two side of knees more than 10 percent, and SSFTB is not finally performed or failed block.