This study employs a randomized controlled trial to investigate whether bupivacaine liposome injection for adductor canal block can effectively improve lower limb muscle strength after total knee arthroplasty.
Patients aged 60-75 years scheduled for elective TKA;
ASA physical status classification II-III;
BMI 18-30 kg/m²;
Agreement to participate in this study and provision of signed informed consent.
Individuals with communication barriers such as language or hearing impairments;
Patients with contraindications to nerve blocks;
Severe systemic diseases, such as severe renal disease (estimated glomerular filtration rate below 50 mL/min), cardiac disease (congestive heart failure New York Heart Association Class III to IV), or severe hepatic disease defined as a current or past diagnosis of acute/subacute hepatic necrosis, acute liver failure, chronic liver disease, liver abscess, hepatic coma, or hepatorenal syndrome;
History of long-term opioid use (defined as daily or nearly daily opioid use within the past 3 months).
Parallel
a single-injection adductor canal block
Procedure/SurgeryAn ultrasound-guided adductor canal block is performed via the conventional adductor canal approach. Under ultrasound guidance, 20 milliliters of 1.33% bupivacaine liposome is injected into the adductor canal.
continuous femoral nerve block
Procedure/SurgeryAn ultrasound-guided perineural sheath block of the femoral nerve is performed via the conventional femoral nerve approach. A femoral nerve catheter is then placed and connected to an analgesia pump containing 150 milliliters of 0.20% ropivacaine.
Quadriceps Muscle Strength
The Maximum Voluntary Isometric Contraction (MVIC) test is used to assess quadriceps strength. The tester holds a handheld dynamometer. The patient sits on the bed with legs hanging naturally, and the knee is flexed to 60°. The patient is instructed to slowly exert force to extend the knee forward. As the patient exerts force, the tester applies an equal and opposite counterforce with the dynamometer to maintain the position and angle of the lower leg. The patient sustains maximum effort for 3-5 seconds, and the peak value displayed on the dynamometer is recorded as the result for that trial. Each leg is tested 2-3 times, with a 60-90 second rest between trials to prevent muscle fatigue from affecting the results. The average value is recorded as the final outcome. The unit of measurement is Newtons (N).
Quadriceps muscle strength at other time points
The Maximum Voluntary Isometric Contraction (MVIC) test is used to assess quadriceps strength. The tester holds a handheld dynamometer. The patient sits on the bed with legs hanging naturally, and the knee is flexed to 60°. The patient is instructed to slowly exert force to extend the knee forward. As the patient exerts force, the tester applies an equal and opposite counterforce with the dynamometer to maintain the position and angle of the lower leg. The patient sustains maximum effort for 3-5 seconds, and the peak value displayed on the dynamometer is recorded as the result for that trial. Each leg is tested 2-3 times, with a 60-90 second rest between trials to prevent muscle fatigue from affecting the results. The average value is recorded as the final outcome. The unit of measurement is Newtons (N).
Numeric Rating Scale (NRS) Score
Using a scale from 0 to 10 to indicate pain intensity, where 0 represents no pain and 10 represents the worst possible pain.
Quadriceps muscle strength grade
Perform a Manual Muscle Test (MMT). The patient is placed in the supine position, with a soft pillow under the knee to provide slight flexion, or sits on the edge of the bed with legs hanging naturally. The examiner stabilizes the patient's thigh with one hand to prevent hip compensation and applies downward resistance with the other hand just above the patient's ankle. Instruct the patient to forcefully extend the knee against the resistance. Observe muscle contraction and joint range of motion, and assess according to the 0-5 grade muscle strength scale.
Knee Joint Range of Motion
Using a goniometer, accurately measure the patient's knee joint flexion and extension range of motion. During measurement, the patient is in the supine position. The axis of the goniometer is aligned with the lateral femoral condyle, the stationary arm is parallel to the long axis of the femur, and the movable arm is parallel to the long axis of the tibia. Record the angles at full knee extension (0°) and maximum flexion separately.
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