Image Interpretation: Focal hypoechogenicity and disruption of the normal fibrillar echotexture at the proximal attachment of the UCL anterior bundle, consistent with a partial tear of the proximal-to-midsubstance region. No complete discontinuity of ligamentous fibers is seen. A PRP injection procedure is visualized, with the needle identified in long axis advancing to the tear site under real-time ultrasound guidance. Findings correlate with the patients clinical presentation and were confirmed on MR arthrography. Repeat ultrasonography at approximately 4 months post-PRP demonstrates interval improvement in fibrillar echotechture with decreased conspicuity of the prior defect of the UCL anterior bundle, correlating with the patient’s clinical recovery and return to prior level of play.

Teaching Pearl: Ultrasound is well suited for serial follow-up after PRP injection because it can reassess ligament morphology, medial elbow stability, and dynamic valgus stress response in the same visit. In a partial proximal UCL tear, interval improvement in fiber continuity or hypoechogenicity is most meaningful when it parallels clinical recovery and activity-specific load tolerance. Ultrasound does not replace MRI for every UCL injury, but it can be a practical, low-cost tool for monitoring healing and guiding return-to-activity decisions after nonoperative treatment or orthobiologic intervention in selected athletes. References: 1. Sutterer BJ, Boettcher BJ, Payne JM, Camp CL, Sellon JL. The role of ultrasound in the evaluation of elbow medial ulnar collateral ligament injuries in throwing athletes. Curr Rev Musculoskelet Med. 2022;15(6):535-546. doi:10.1007/s12178-022-09793-0 2. Kato Y, Yamada S, Chavez J. Can platelet-rich plasma therapy save patients with ulnar collateral ligament tears from surgery? Regen Ther. 2019;10:123-126. doi:10.1016/j.reth.2019.02.004 3. Fucaloro SP, Kang AS, Bragg JT, Krivicich L, Salzler MJ. Return to sport after ulnar collateral ligament tears treated with platelet-rich plasma injections is influenced by length of rehabilitation and leukocyte content of injections: a systematic review. Arthroscopy. 2025;41(2):343-356. doi:10.1016/j.arthro.2024.03.017