The Elias University Hospital Approach: A Visual Guide to Ultrasound-Guided Botulinum Toxin Injection in Spasticity: Part III-Proximal Lower Limb Muscles

Abstract

Ultrasound-guided botulinum toxin type A (BoNT-A) injections have become an essential tool in the management of lower limb spasticity. Following our previous work, which focused on upper limb muscles, this third part provides a detailed visual guide to the identification and injection of proximal lower limb muscles frequently involved in spastic gait and posture disorders. This guide presents the ultrasound anatomy, clinical relevance, and injection strategies for eleven key muscles: gluteusmaximus, piriformis, psoas major, rectusfemoris, sartorius, gracilis, adductorlongus, adductormagnus, semimembranosus, semitendinosus, and bicepsfemoris. For each muscle, the Elias University Hospital (EUH) model is applied, highlighting the zones of maximum thickness and motor point density to ensure precise and effective BoNT-A delivery. Enhanced with high-resolution ultrasound images and dynamic scanning techniques, this visual guide supports clinicians in performing safe, targeted injections. It serves as both an educational and practical reference for the ultrasound-guided treatment of spasticity in the proximal lower limb, completing the series and offering a standardized framework for comprehensive BoNT-A management. By promoting accurate toxin delivery, this approach is expected to improve functional mobility, reduce spasticity-related complications, and optimize patient-centered outcomes in rehabilitation settings.

Keywords: botulinum toxin-A injections; musculoskeletal ultrasound; post-stroke spasticity; proximal lower limb muscles; ultrasound-guided therapy.

Figure 1

Ultrasound anatomy of gluteus maximus (Gmax) with key landmarks: Gmax—gluteus maximus; Gmed—gluteus medius; Gmin—gluteus minimus; I—iliac bone.

Figure 2

Ultrasound anatomy of piriformis with key landmarks: Gmax—gluteus maximus; Ace—acetabulum; S—sciatic nerve.

Figure 3

Ultrasound anatomy of psoas major (PM) (with the transducer transversely) with key landmarks: PM—psoas major; L4—spinous process of the L4 vertebra; ES—erector spinae; QL—quadratus lumborum.

Figure 4

Ultrasound anatomy of psoas major (PM) (with the transducer longitudinally) with key landmarks: QL—quadratus lumborum; PM—psoas major.

Figure 5

Ultrasound anatomy of rectus femoris (RF) with key landmarks: RF—rectus femoris; RFt—rectus femoris tendon; VI—vastus intermedius; F—femur.

Figure 6

Ultrasound anatomy of sartorius (Sart) with key landmarks: Sart—sartorius; FV—femoral vein; FA—femoral artery; SN—saphenous nerve; NtVM—nerve to vastus medialis; AL—adductor longus; VM—vastus medialis; AM—adductor magnus; F—femur.

Figure 7

Ultrasound anatomy of gracilis (G) with key landmarks: G—gracilis; AM—adductor magnus; SM—semimembranosus; F—femur.

Figure 8

Ultrasound anatomy of adductor longus (AL) with key landmarks: AL—adductor longus; AB—adductor brevis; AM—adductor magnus; F—femur.

Figure 9

Ultrasound anatomy of adductor magnus (AM) with key landmarks: G—gracilis; AM—adductor magnus; SM—semimembranosus; F—femur.

Figure 10

Ultrasound anatomy of semimembranosus (SM) with key landmarks: SM—semimembranosus; ST—semitendinosus; AM—adductor magnus; v—vein, a—artery, F—femur.

Figure 11

Ultrasound anatomy of semitendinosus (ST) with key landmarks: ST—semitendinosus; SM—semimembranosus; AM—adductor magnus; F—femur.

Figure 12

Mercedes-Benz sign: ST—semitendinosus; BF—biceps femoris, S—sciatic nerve; AM—adductor magnus; F—femur.

Figure 13

Ultrasound anatomy of biceps femoris (BF) with key landmarks: BFl—biceps femoris long head; IMF—intramuscular fascia; BFs—biceps femoris short head; S—sciatic nerve; F—femur.