Ultrasound-Guided Injection of the Posterior Talofibular Ligament Using a Bony Landmark-Based Approach: A Technical Report With Cadaveric Demonstration of Feasibility.

The posterior talofibular ligament (PTFL) is the deepest and strongest component of the lateral ankle ligament complex, yet it is infrequently evaluated or targeted in routine musculoskeletal ultrasound practice because of its deep location and surrounding anatomy. This technical report describes a structured ultrasound-guided PTFL injection technique based on sequential bony landmark identification and dynamic localization of the flexor hallucis longus (FHL) tendon. Ultrasound images demonstrating the scanning protocol were obtained from a healthy volunteer after written informed consent. A cadaveric demonstration of feasibility was then performed in one fresh-frozen specimen using ultrasound-guided injection of 2 mL of a commercially available cosmetic hyaluronic acid-based filler mixed with green dye at the talar insertional region of the PTFL, followed by layer-by-layer dissection. The scanning approach allowed identification of the PTFL through cranial-to-caudal assessment of the posterior ankle, medial probe translation to define the posterior malleolus and posterior process of the talus, and dynamic confirmation of the FHL tendon. Gross dissection demonstrated focal dye localization in the region of the PTFL talar insertion, predominantly beneath the transverse intermuscular septum, without gross spread to adjacent superficial neurovascular structures in this specimen. These findings support the anatomical plausibility of the intended target region in this technical setting. In a potential clinical context, PTFL-region injection may be relevant in selected cases of persistent posterior ankle symptoms, posterior impingement, or incompletely explained instability, either for diagnostic symptom localization or as a framework for future targeted therapeutic interventions. However, because feasibility assessment was limited to a single cadaveric specimen and gross dissection alone, and because the surrogate cadaveric injectate was selected for anatomical visualization rather than treatment simulation, the technique should not be interpreted as establishing selective intraligamentous placement, optimal therapeutic injectate volume, clinical efficacy, procedural accuracy, or formal safety. Further anatomical, prospective, and comparative studies are warranted.