Anatomical Accuracy of Palpation-Guided Dry Needling in Lateral Epicondylitis

Study Design and Muscle Selection

This prospective, single-center anatomical accuracy study was conducted in patients with lateral epicondylitis. The study evaluated the accuracy of palpation-guided dry needling targeting four forearm muscles: extensor digitorum communis (EDC), extensor carpi radialis brevis (ECRB), extensor carpi radialis longus (ECRL), and brachioradialis (BR).

Patients underwent clinical examination to identify active myofascial trigger points (MTrPs). When active MTrPs were identified in more than one muscle, pressure pain thresholds were measured using a digital algometer (FPX 25, Wagner Instruments) with a 1 cm² probe. The muscle with the lowest pressure pain threshold was selected for dry needling. Target-muscle selection was not randomized, and each participant underwent needling of one selected muscle.

During algometric assessment, ultrasound was used to verify that the algometer probe was positioned over the intended muscle rather than an adjacent muscle. Ultrasound was not used to guide needle insertion. A minimum interval of 10 minutes was maintained between algometric assessment and dry needling.

Palpation-Guided Dry Needling Procedure

All dry needling procedures were performed by a single experienced physician using palpation and anatomical landmarks without real-time ultrasound guidance. Patients were positioned supine, and the skin was sterilized before needle insertion.

A Hua-Long 0.30 × 30 mm single-use sterile acupuncture needle was used. The insertion site and direction were determined according to the anatomical characteristics of the selected muscle. Needle insertion depth was limited to 20 mm for EDC and ECRB and 15 mm for ECRL and BR.

Ultrasound Verification of Needle Placement

Immediately after needle insertion, an independent sonographer with 10 years of experience in musculoskeletal ultrasonography evaluated needle-tip placement using a high-frequency linear ultrasound probe (5-12 MHz; Clarius, Canada).

The sonographer was not informed of the intended target muscle before anatomical verification. However, the skin entry point, patient positioning, and needle trajectory were visible during the assessment.

The needle tip was identified using direct ultrasound visualization in transverse and longitudinal planes. Muscle identification was based on anatomical landmarks, including the radius, adjacent extensor muscles, and intermuscular fascial boundaries.

The ultrasound-confirmed anatomical location was documented separately and communicated to the needling physician, who compared it with the intended target muscle. Placement was classified as correct when the needle tip was visualized within the intended muscle and incorrect when it was located in another anatomical structure.

Conservative Management

After completion of dry needling and ultrasound verification, all participants received standard conservative management consisting of a wrist splint for two weeks and a home exercise program involving daily eccentric strengthening and stretching of the wrist extensor muscles (3 sets of 10 repetitions per day for two weeks).

Conservative treatment was initiated after anatomical accuracy assessment and therefore did not influence the primary outcome.

Primary Outcome

The primary outcome was anatomical needle-placement accuracy, defined as the proportion of needling procedures in which the needle tip was correctly located within the intended target muscle, as verified by ultrasound. Accuracy was evaluated separately for EDC, ECRB, ECRL, and BR.