Efficacy of IPACK Block Combined With Intra-articular Steroid Injection in Advanced Knee Osteoarthritis: A Retrospective Cohort Study

Osteoarthritis (OA) is a degenerative joint disease characterized by the progressive degeneration of articular cartilage resulting from the interaction of genetic, metabolic, and biochemical factors and is often accompanied by secondary inflammation. This condition represents a pathological process involving the dynamic interaction of cartilage degradation and repair mechanisms affecting the cartilage, subchondral bone, and synovium. Osteoarthritis is the most common joint disease worldwide and represents one of the leading causes of physical disability.

Pain is the most prominent symptom of osteoarthritis. It typically increases with activity and decreases with rest. As the disease progresses, pain may occur with minimal activity and can eventually be present at rest and during the night.

The knee joint is a synovial joint formed between the femoral condyles and the tibia. Sensory innervation of the knee joint is provided by branches of the femoral, obturator, and sciatic nerves. Pain associated with knee osteoarthritis is a common clinical problem that can lead to functional limitation and reduced quality of life. In many patients with chronic knee pain due to osteoarthritis, pharmacological treatments and/or physical therapy may not provide sufficient analgesia. Knee arthroplasty is the most frequently used treatment option for advanced knee osteoarthritis; however, it may not be suitable for some patients because of comorbidities.

Currently, one of the most commonly used interventional treatment methods for pain control in knee osteoarthritis is intra-articular steroid injection. This treatment reduces synovial inflammation and may slow disease progression. However, repeated steroid injections may provide only short-term pain relief and may also contribute to cartilage degeneration.

In recent years, alternative interventional approaches for the management of osteoarthritis-related knee pain have gained increasing attention. The nerves responsible for knee joint pain originate from both the anterior and posterior aspects of the joint. The IPACK (infiltration between the popliteal artery and the capsule of the knee) block is a simple and practical technique performed under ultrasound guidance. Although it is primarily intended to block the posterior articular innervation of the knee, cadaveric studies suggest that the anterior genicular nerves may also be affected. Therefore, the IPACK block may serve as an alternative treatment option for providing additional analgesia in patients with advanced knee osteoarthritis.

The aim of this study was to investigate the effects of an IPACK block combined with intra-articular steroid injection on pain scores in patients with chronic knee osteoarthritis.

Study Overview

• Status: Completed
• Conditions: Ultrasound Guided Injection; IPACK Block Multimodal Analgesia; Knee Osteoarthritis (Knee OA); Intraarticular Injection

Detailed Description

Patients presenting to a tertiary hospital in Istanbul, Turkey, between January 2024 and September 2025 with knee pain and diagnosed with stage 3-4 knee osteoarthritis based on clinical and radiological findings were scheduled for the procedure. The procedure was performed on only one knee, and the contralateral knee was not treated.

On the morning of the procedure, patients' NRS-11 and WOMAC scores were recorded. After being taken to the operating room, patients were placed in the supine position. Electrocardiography, pulse oximetry, and non-invasive blood pressure monitoring were performed. Intravenous access was established. The painful knee area was prepared and draped in a sterile manner using a povidone-iodine-based solution. Ultrasonography (US) was used to visualize the knee joint and surrounding structures.

In patients undergoing intra-articular steroid injection (IASI), a 22-gauge, 90-mm needle was advanced from the suprapatellar region into the joint space under ultrasound guidance. After puncturing the joint capsule, a mixture of 4 ml of 1% lidocaine and 40 mg of triamcinolone acetonide was injected into the joint.

Patients undergoing IASI + IPACK (infiltration between the popliteal artery and the posterior capsule of the knee) block were also placed in the supine position with standard monitoring and sterile preparation. First, the IASI procedure was performed as described above. Then, a pillow was placed under the knee to achieve approximately 30° of flexion. Using an ultrasound-guided medial approach, the probe was positioned approximately 2-3 cm above the patella level, starting from the distal medial femoral epicondyle. Subsequently, a 22-gauge, 90-mm needle was advanced to the space between the posterior joint capsule and the popliteal vessels at the level where the femoral condyles end and the femoral shaft begins. A total of 15 mL of a mixture containing 0.25% bupivacaine and 4 mg dexamethasone was injected.

After the procedure, patients were observed in the inpatient ward for at least 2 hours to monitor for potential adverse effects. One week after the injection, all patients were provided with an exercise booklet to guide their home-based rehabilitation program.

Patients were advised to use 500 mg paracetamol (up to four tablets per day) as needed for pain control. They were instructed not to take any analgesics on the day of follow-up assessments, as this could affect clinical outcome measures. Paracetamol consumption was recorded at the end of the 1st and 6th months. NRS-11 and WOMAC scores were also recorded at the 1st and 6th months during outpatient clinic visits.

• Study Type: Observational
• Enrollment (Actual): 98

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Istanbul
    • Küçükçekmece, Istanbul, Turkey (Türkiye), (507) 277-4773
      • Kanuni Sultan Suleyman Training and Research Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

Patients presenting to a tertiary hospital in Istanbul, Turkey, with knee pain and diagnosed with stage 3-4 knee osteoarthritis based on clinical and radiological findings between January 2024 and September 2025 were included in the study. The procedure was performed on a single knee, and the contralateral knee was not treated.

Description

Inclusion Criteria:

• Patients over 40 years of age
• Diagnosed with primary knee osteoarthritis according to ACR (American College of Rheumatology) criteria based on clinical, radiological, and laboratory evaluations
• Activity VAS score of 5 or higher despite previous medical and physical therapy
• Patients with stage 3-4 knee osteoarthritis according to the Kellgren-Lawrence classification
• Patients without motor or sensory loss on neurological examination
• Patients who signed an informed consent form
• Patients who have not undergone any interventional procedures on the knee within the last 6 months

Exclusion Criteria:

• Patients with bleeding or coagulation disorders
• Patients with sepsis or local infection at the intervention site
• Patients with allergies to any of the medications to be used
• Patients without study consent
• Patients with secondary osteoarthritis
• Patients who have undergone knee interventions in the last 6 months
• Patients who have undergone knee surgery
• Psychosis

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Comparison of the Effectiveness of Ultrasonography-Guided Intra-Articular Steroid Injection and IPAC

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
1. Numeric Rating Scale (NRS-11): The NRS-11 is an 11-point numerical scale (9) that allows patients to rate their pain from 0 (no pain at all) to 10 (the most severe pain they have ever experienced). It was assessed three times: pre-treatment, 1 month a	6 month

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC):	It is a standardized questionnaire widely used by healthcare professionals to assess the condition of patients with knee and hip osteoarthritis, including pain, stiffness, and physical function of the joints. It was developed in 1982 by Western Ontario and McMaster Universities. Higher scores indicate worse pain, stiffness, and functional limitations. The WOMAC consists of five items for pain (score range 0-20), two items for stiffness (score range 0-8), and 17 items for functional limitations (score range 0-68).	6 month

Collaborators and Investigators

• Sponsor: Kanuni Sultan Suleyman Training and Research Hospital
• Collaborators: Prof. Dr. Cemil Tascıoglu Education and Research Hospital Organization

Study record dates

Study Major Dates

• Study Start (Actual): December 5, 2025
• Primary Completion (Actual): December 10, 2025
• Study Completion (Actual): December 23, 2025

Study Registration Dates

• First Submitted: November 25, 2025
• First Submitted That Met QC Criteria: November 25, 2025
• First Posted (Actual): December 8, 2025

Study Record Updates

• Last Update Posted (Actual): March 11, 2026
• Last Update Submitted That Met QC Criteria: March 9, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Arthritis; Joint Diseases; Rheumatic Diseases; Osteoarthritis; Osteoarthritis, Knee
• Other Study ID Numbers: knee osteoarthritis

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

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