Osteoarthritis (OA) is a leading cause of chronic musculoskeletal pain and functional disability worldwide, affecting an increasing number of people. Despite various conservative and interventional treatment approaches, pain, the most important clinical problem in the disease, is suboptimally controlled. Hip osteoarthritis is a chronic condition characterized by progressive degeneration of the joint cartilage and inflammation of the synovial membrane. The incidence of symptomatic hip OA is estimated to be approximately 25%, and its prevalence is increasing due to the aging of the global population and the rise in obesity (1). Conservative methods such as oral medications and physical therapy modalities are available for its management. However, in some patients, pain persists despite these conservative treatment methods, and ongoing pain significantly impairs patients' daily living activities. There are some interventional treatment methods used in these patients, and the most commonly used methods are intra-articular corticosteroid (CS) and local anesthetic (LA) injections and, in some patients, a pericapsular nerve (PENG) block administered in addition to these injections.

In this observational study, we will obtain information on the treatment response of patients who previously underwent hip joint injections guided by ultrasound and PENG block in addition to joint injections for hip pain unresponsive to medical treatment, as well as information that we believe may affect treatment response, such as patient age, gender, and disease duration, by reviewing patient files. The patients' treatment response will be evaluated according to the Visual Analog Scale (VAS) and Western Ontario and McMaster Universities Arthritis (WOMAC) index scores, and the pain scores obtained from the patient records before the procedure and one month, three months, and six months after the procedure will be compared. When examining patients for treatment success, the treatment outcomes of patients who received only intra-articular injections will be compared with those who received intra-articular injections + PENG blocks. Current evidence shows that intra-articular steroid injections provide symptomatic relief in hip OA and are recommended for non-surgical treatment. During the procedure, the patient is placed supine, and following sterile cleaning and draping, the ultrasound probe is placed transversely over the inguinal region. After visualizing the femoral head and femoral artery, vein, and nerve, local anesthesia with 1% lidocaine is applied to the needle insertion site after visualizing the femoral head and neck junction and the articular cartilage. Then, a 22-gauge, 100-mm needle is advanced toward the joint capsule, targeting the junction of the femoral neck and femoral head.After reaching the target area, 2 ml of dexamethasone and 2 ml of 0.025% bupivacaine are injected into the joint.

The pericapular nerve group (PENG) block is a treatment applied to block sensory nerve branches, including the articular branches of the femoral nerve, obturator nerve, and accessory obturator nerve that innervate the anterior joint capsule, and is frequently used in our clinic in conjunction with joint injection for hip pain. During the procedure, the patient is placed supine, and following sterile cleaning and draping, the anterior inferior iliac spine (AIIS) and iliopubic eminence (IPE) are visualized using a convex ultrasound probe. The target for the PENG block is the musculo-fascial plane between the psoas tendon anteriorly and the pubic ramus posteriorly. After applying local anesthesia to the skin with 1% lidocaine, a 22-gauge, 100 mm needle is inserted and 2 ml of dexamethasone and 2 ml of 0.025% bupivacaine are injected into the target area. Patients are monitored for possible complications.

The primary objective of our study is to compare the treatment responses of patients diagnosed with hip OA who have undergone hip intra-articular injection and/or PENG block therapy and to investigate the effect of PENG block added to intra-articular injection on pain and functionality. The secondary objective is to evaluate other parameters (age, gender, disease duration, analgesic use, etc.) that may influence treatment outcomes at 6 months. The study protocol was approved by the local ethics committee, and the study was conducted in accordance with the principles of the Declaration of Helsinki.

Inclusion Criteria:

• Patients with hip pain due to hip osteoarthritis who have undergone hip intra-articular steroid + local anesthetic injection and/or PENG block under ultrasound guidance for this reason
• Persistence of pain for more than 6 months
• Failure of pain treatment with conservative methods

Exclusion Criteria:

• Those with inflammatory rheumatic joint disease (rheumatoid arthritis, gout, pseudogout, metabolic joint diseases),
• History of major trauma, hip surgery
• Cognitive dysfunction, history of psychiatric illness
• Hepatic or renal insufficiency
• Local or systemic infection
• Coagulopathy

Patients with hip pain lasting longer than 6 months due to hip osteoarthritis that has not improved with conservative methods and who have therefore undergone ultrasound-guided intra-articular steroid + local anesthetic injection and/or PENG block.