Comparison of BiFeS + ACB and IPACK + ACB Block Combinations for Postoperative Pain After Total Knee Arthroplasty

Comparative Evaluation of Biceps Femoris Short Head (BiFeS) and Adductor Canal Block and Interspace Between the Popliteal Artery and Capsule of the Knee (IPACK) and Adductor Canal Block Combinations for Postoperative Pain After Total Knee Arthroplasty

This prospective observational study will compare the postoperative analgesic efficacy of two multimodal regional anesthesia combinations routinely used after total knee arthroplasty (TKA) performed under spinal anesthesia. The study will observe patient groups who receive, as part of standard clinical practice, either the Biceps Femoris Short Head (BiFeS) block combined with the Adductor Canal Block (ACB) or the Interspace Between the Popliteal Artery and the Capsule of the Knee (IPACK) block combined with the Adductor Canal Block (ACB). The research team will not assign, perform, or direct any blocks; all regional anesthesia procedures will be administered independently by anesthesiologists experienced in ultrasound-guided regional anesthesia as part of routine care.

Postoperative pain will be observed and documented using the Numeric Rating Scale (NRS) at multiple time points within the first 24 hours. Opioid consumption will be recorded based on intravenous patient-controlled analgesia (PCA) data, and the need for rescue analgesia will be noted. Additional postoperative observations will include functional recovery, quality of recovery scores, and the incidence of adverse events.

Postoperative pain will be evaluated using the Numeric Rating Scale (NRS) at multiple time points within the first 24 hours. Opioid consumption will be recorded through intravenous patient-controlled analgesia (PCA), and the need for rescue analgesia will be assessed. Additional postoperative observations will include functional recovery, quality of recovery scores, and the incidence of adverse events.

Study Overview

• Status: Completed
• Conditions: Pain, Postoperative; Arthroplasty, Replacement, Knee; Pain After Total Knee Arthroplasty
• Intervention / Treatment: Procedure: ltrasound-Guided Biceps Femoris Short Head (BiFeS) Block Combined with Adductor Canal Block (ACB); Procedure: Ultrasound-Guided Interspace Between the Popliteal Artery and the Capsule of the Knee (IPACK) Block Combined with Adductor Canal Block (ACB)

Detailed Description

This prospective, single-center, observational study will be conducted at Karabük Training and Research Hospital. This is an observational study. Participants are not assigned to any intervention by the research team. All regional anesthesia blocks are performed as part of routine clinical practice, and the investigators only collect data related to outcomes. No interventions are administered because of study participation. The research team does not perform, modify, or direct any clinical procedures; all blocks are performed independently as part of routine care.

The study population will include adults aged 18-80 years undergoing elective unilateral total knee arthroplasty (TKA) under spinal anesthesia. All eligible patients will receive routine multimodal analgesia and will undergo one of two commonly used regional anesthesia combinations:

Biceps Femoris Short Head (BiFeS) block + Adductor Canal Block (ACB)

Interspace Between the Popliteal Artery and the Capsule of the Knee (IPACK) block + Adductor Canal Block (ACB)

The choice of block combination will be determined by the attending anesthesiologist as part of standard clinical practice. The research team will not influence clinical decisions and will only record perioperative and postoperative data.

Regional Anesthesia Techniques (Routine Care Descriptions)

IPACK Block: The patient will remain in the supine position with the knee flexed 30-45°. A 3.5-6 MHz convex US probe will be placed over the popliteal fossa to visualize the popliteal artery at the femoral condyle level in the short axis. A 22G, 100 mm needle will be advanced in-plane from lateral to medial, and the tip will be positioned between the popliteal artery and femoral condyle. After negative aspiration, 25 mL 0.25% bupivacaine will be slowly injected.The aim is to provide effective posterior knee analgesia by blocking the sensory branches without motor impairment.

BiFeS Block: With the patient in the supine position, the potential space between the lateral supracondylar line of the femur and the short head of the BF muscle will be identified under US guidance. A 22G, 100 mm echogenic needle will be advanced in-plane, and 25 mL 0.25% bupivacaine will be injected. All blocks will be performed by anesthesiologists experienced in ultrasound-guided regional anesthesia.

ACB: ACB will also be performed in the same session using 15 mL 0.25% bupivacaine beneath the sartorius muscle under US guidance.

Anesthesia and Analgesia Approach

All patients will undergo spinal anesthesia as part of routine care. Postoperative analgesia will include multimodal medications used in standard practice at the study center, as well as intravenous patient-controlled analgesia (PCA) when required. Pain intensity will be assessed using the Numeric Rating Scale (NRS), an 11-point scale ranging from 0 (no pain) to 10 (worst imaginable pain). Opioid use will be calculated in morphine milligram equivalents (MME).

Outcome Assessments

Postoperative outcomes will include cumulative opioid consumption at 12 and 24 hours, pain scores at predefined time points, quality of recovery using the Quality of Recovery-15 (QoR-15) questionnaire, postoperative nausea and vomiting (PONV) scores, block performance time, time to first mobilization, functional evaluation with the Timed Up and Go (TUG) test, block-related and opioid-related complications, and total length of hospital stay.

• Study Type: Observational
• Enrollment (Actual): 60

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Karabük Province
    • Karabük, Karabük Province, Turkey (Türkiye), 78200
      • Karabuk Training and Research Hospital, Department of Anesthesiology and Reanimation

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

This study will include adult patients aged 18-80 years undergoing elective unilateral total knee arthroplasty (TKA) under spinal anesthesia at Karabük Training and Research Hospital. Eligible participants will have ASA physical status I-III and be capable of using patient-controlled analgesia (PCA). Patients will be prospectively observed as part of routine multimodal analgesia including either BiFeS + ACB or IPACK + ACB block combinations for postoperative pain management.

Description

Inclusion Criteria:

• Adults aged 18-80 years scheduled for elective unilateral total knee arthroplasty (TKA) under spinal anesthesia
• ASA physical status I-III
• Eligible for and capable of using patient-controlled analgesia (PCA)
• Provided written informed consent

Exclusion Criteria:

• Chronic opioid use for more than four weeks before surgery
• Presence of chronic pain conditions (e.g., migraine, fibromyalgia)
• History of alcohol or drug abuse
• Known allergy or hypersensitivity to local anesthetics or opioids
• Severe organ dysfunction (e.g., significant hepatic or renal disease)
• Revision or bilateral knee arthroplasty
• Contraindications to regional anesthesia
• Preexisting neuropathy or prior femoral vascular surgery on the operated side.
• Infection near the injection site (e.g., osteomyelitis, septic joint).
• Contraindication to spinal anesthesia (e.g., refusal, coagulopathy, use of anticoagulants or antiplatelet agents) or inability to understand NRS.
• Severe psychiatric or cognitive disorders (e.g., psychosis, dementia) that prevent cooperation or pain assessment
• Pregnant or breastfeeding women

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Group BiFeS; Adductor canal block and BiFeS block ( 15 ml %0.25 bupivacaine and 25 ml %0.25 bupivacaine) + IV morphine patient-controlled analgesia (PCA)	Procedure: ltrasound-Guided Biceps Femoris Short Head (BiFeS) Block Combined with Adductor Canal Block (ACB); BiFeS block will be performed after spinal anesthesia (15 mg bupivacaine) in TKA patients. With the patient in the supine position, the potential space between the lateral supracondylar line of the femur and the short head of the BF muscle will be identified under US guidance. A 22G, 100 mm echogenic needle will be advanced in-plane, and 25 mL 0.25% bupivacaine will be injected. ACB will be performed in the same session by injecting 15 mL 0.25% bupivacaine beneath the sartorius muscle. All blocks will be performed under sterile conditions and US guidance by experienced anesthesiologists.
Group IPACK; Adductor canal block and IPACK block ( 15 ml %0.25 bupivacaine and 25 ml %0.25 bupivacaine) + IV morphine patient-controlled analgesia (PCA)	Procedure: Ultrasound-Guided Interspace Between the Popliteal Artery and the Capsule of the Knee (IPACK) Block Combined with Adductor Canal Block (ACB); IPACK block will be performed after spinal anesthesia (15 mg bupivacaine) in TKA patients. The patient will remain in the supine position with the knee flexed 30-45°. A 3.5-6 MHz convex US probe will be placed over the popliteal fossa to visualize the popliteal artery at the femoral condyle level in the short axis. A 22G, 100 mm needle will be advanced in-plane from lateral to medial, and the tip will be positioned between the popliteal artery and femoral condyle. After negative aspiration, 20 mL 0.25% bupivacaine will be slowly injected. The aim is to provide effective posterior knee analgesia by blocking the sensory branches without motor impairment. ACB will also be performed in the same session using 15 mL 0.25% bupivacaine beneath the sartorius muscle under US guidance. All blocks will be performed under sterile conditions by experienced anesthesiologists.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cumulative opioid consumption in the first 24 hours after surgery	Morphine consumption in the first 24 hours after surgery will be measured. Patients will be able to request opioids via a PCA device when their NRS score is ≥ 4.	Postoperative day 1

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time of first analgesic request	Time at which the first analgesic is requested	Postoperative day 1
Cumulative opioid consumption in the first 12 hours after surgery	Morphine consumption in the first 12 hours after surgery will be measured. Patients will be able to request opioids via a PCA device when their NRS score is ≥ 4.	postoperative 12th hour
Block performance time	The duration of block performance will be recorded for BiFeS, ACB, and IPACK procedures. Time will be measured in seconds from the placement of the ultrasound probe on the skin to the completion of local anesthetic injection.	İntraoperative period
The Quality of Recovery-15 (QoR-15) score	Patient recovery quality and satisfaction will be assessed using the QoR-15 questionnaire at 24 hours postoperatively and at discharge. Higher scores indicate better recovery (QoR-15 score [0-150]).	24 hours postoperatively and postoperative day 2-4
Number of patients requiring rescue analgesia	Number of patients who required additional rescue analgesics (IV tramadol 100 mg) despite PCA use will be recorded.	Postoperative day 1
Block-related complications	Complications related to the block procedure, such as local bleeding, hematoma, infection, or local anesthetic systemic toxicity (LAST), will be recorded.	Postoperative day 7
Opioid-related side effects	Adverse effects including pruritus, sedation, fatigue, or respiratory depression associated with opioid use will be documented.	Postoperative day 7
Timed Up and Go (TUG) test duration	The time (in seconds) taken for the patient to rise from a chair, walk 3 meters, return, and sit down will be recorded as a measure of functional mobility.	Postoperative day 1
Length of hospital stay	Total time from entry to the operating room until discharge from the hospital will be recorded.	From surgery to postoperative day 2-4
Postoperative pain scores	Pain status at rest and while activity will be assessed by numeric rating scale (NRS) score at 0, 3, 6, 12, 18 and 24 hours after surgery. In addition, the time until the first analgesic requirement will be recorded. The NRS is an 11-point numeric scale that ranges from 0 to 10.	Postoperative day 1
The postoperative nausea and vomiting (PONV) scores and the number of patients requiring antiemetic medication	The severity of postoperative nausea and vomiting (PONV) will be assessed using a descriptive verbal rating scale at 0, 3, 6, 12, 18 and 24 hours after extubation. If a score of 3 or more, ondansetron 4 mg IV will be administered and will repeat after 8 hours if required (The PONV scale is 0 = no nausea; 1 = slight nausea; 2 = moderate nausea; 3 = vomiting once; and 4 = vomiting more than once).	Postoperative day 1
Time to first mobilization	Time elapsed from the end of surgery to the patient's first mobilization (standing and walking with physiotherapist assistance) will be recorded.	Postoperative day 1 and postoperative day 2-4

Collaborators and Investigators

• Sponsor: Karabuk University
• Investigators: Principal Investigator: Elif Sarikaya Özel, M.D., Karabuk Training and Research Hospital, Department of Anesthesiology and Reanimation

Study record dates

Study Major Dates

• Study Start (Actual): October 15, 2025
• Primary Completion (Actual): January 30, 2026
• Study Completion (Actual): January 31, 2026

Study Registration Dates

• First Submitted: November 13, 2025
• First Submitted That Met QC Criteria: November 14, 2025
• First Posted (Actual): November 17, 2025

Study Record Updates

• Last Update Posted (Actual): February 3, 2026
• Last Update Submitted That Met QC Criteria: January 31, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Postoperative Complications; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain, Postoperative
• Other Study ID Numbers: BiFeS2025/2462

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No