The aim of this study is to evaluate the accuracy of invasive interventions (dry needling or injection) performed on specific muscles of the hip region in reaching the anatomical target. The accuracy of the interventions performed with a blinded method will be compared with an observational assessment supported by ultrasonography. The interventions will be performed by a physician with clinical experience, and the anatomical location of the needle tip will be evaluated by a second physician with ultrasonography after each procedure. The targeted muscles include the iliacus, pectineus, sartorius, tensor fascia latae, and rectus femoris. Each participant will be subjected to interventions for five different muscles, and a total of at least 40 injection interventions will be analyzed. Ultrasonography will be used only for observation and verification purposes; no pharmacological substances will be applied during the procedure. All procedures will be performed under sterile conditions, and participants will be monitored for 24 hours for possible pain, bruising, or complications. Participants will be informed about the content and purpose of the study, and written informed consent forms will be obtained. The study does not have a therapeutic purpose and is only intended to investigate targeting accuracy. The data to be obtained is expected to contribute to the determination of anatomical accuracy rates in clinical practices and the improvement of interventional training processes.

This study aims to evaluate the accuracy of muscle targeting when dry needling injections are performed using the blinded (anatomical landmark-based) technique. The accuracy of these injections will be assessed by confirming the needle placement with ultrasonography immediately after each attempt.

According to existing literature, the accuracy of blinded injection techniques is reported to be approximately 67%, while ultrasound-guided injections achieve an accuracy of about 92%. A power analysis was conducted using these proportions to detect a statistically significant difference between the two methods. Based on these values, Cohen's h effect size was calculated as 0.66. With a significance level (alpha) of 0.05 and a statistical power of 80%, a minimum of 74 injection attempts are required.

In this study, each participant will receive injections into five different muscles suspected to be involved in myofascial pain. With 15 participants, this will result in 75 injection attempts, thereby meeting the required sample size for adequate power.

Eligible participants will be adults aged 18-65 presenting with nonspecific hip, groin, or anterior thigh pain and referred for physical therapy. The study particularly focuses on individuals with suspected myofascial pain syndrome in deep or less accessible hip-related muscles, such as the iliacus, pectineus, and sartorius. All participants must be clinically indicated for dry needling or similar interventions and capable of cooperating with the procedure.

Ultrasonographic evaluation will be used only to confirm needle placement, not to guide the injection. This allows for the assessment of the real-world accuracy of the blinded technique, which is commonly used in routine clinical practice. The findings will provide insight into the reliability of this method and help guide training and clinical decision-making in musculoskeletal and pain management practices.

Inclusion Criteria:

• Adults aged 18 to 65 years
• Individuals with nonspecific hip, groin, or anterior thigh pain who are scheduled for physical therapy
• Clinical suspicion of myofascial pain syndrome, particularly involving muscles around the hip
• Patients with clinical indication for dry needling or similar invasive treatments (e.g., targeting muscles such as iliacus, pectineus, sartorius)
• Ability to cooperate with the procedure
• Ability to provide written informed consent

Exclusion Criteria:

• Use of anticoagulant medications (due to increased risk of bleeding)
• Severe hip osteoarthritis, presence of hip prosthesis, history of previous hip surgery, or significant anatomical deformity
• Active infection or skin lesion at the planned injection site
• Inability to cooperate or communicate effectively
• Pregnancy
• Presence of serious systemic illnesses (e.g., malignancy, neurological disorders)

There is no plan to share individual participant data (IPD) from this study.