In the field of podiatry, the concepts of retrocapital support are essential to understand the solutions proposed for various foot pathologies, particularly those related to the metatarsals. In this article, we will explore the three types of retrocapital support: ARCI (internal retrocapital support), ARCE (external retrocapital support), and ARCM (median retrocapital support). Each type of support has specific indications, and understanding them is crucial for optimal podiatric care.
What is retro-capital support?
A retro-capital support is a support area located behind the metatarsal heads. These supports are used to redistribute pressure forces on the forefoot, thus avoiding pain and deformities caused by excessive overload on certain areas. The objective is to protect the metatarsal heads and correct certain anomalies of the forefoot.
ARCI: internal retro-capital support
ARCI focuses on unloading the medial metatarsal heads (M1, M2, M3). This support is particularly useful when seeking to relieve pressure on the inside of the foot, without correcting a valgus foot.
Limits and reliefs of the ARCI:
- Anterior: Follows the retro-capital line of M1, M2, and M3, forming a concave curve forward at the level of the first metatarsal neck.
- Posterior: Concave at the back, it joins the internal Lisfranc marker, medially.
- Lateral: A curve with laterally convexity that joins the anterolateral boundary to the posterolateral boundary.
- Medial: Straight, this limit joins the anteromedial limit to the posteromedial limit with a slight overhang to adapt to the shoe.
In terms of relief, the ARCI has an "airplane wing" shape, with a peak located at the union of the 45th posterior of the 15th anterior. This type of support is designed to unload the medial metatarsal heads and reduce the pressures exerted on this area.
ARCE: external retro-capital support
The ARCE is intended to unload the lateral metatarsal heads (M4, M5). This support is particularly effective in combating excessive supination of the forefoot, especially if the material used is sufficiently rigid.
Limits and reliefs of the ARCE:
- Anterior: Follows the line of the M2, M3, M4, and M5 collars.
- Posterior: Confused with the lateral/external half of the Lisfranc joint space.
- Lateral: Straight, it extends slightly beyond the first sole, not being able to project inside it.
- Medial: Curve with slight medial convexity, it joins the anterior and posterior limits.
For reliefs, the ARCE can present two possibilities: an "airplane wing" shape with a peak located at the union of the 45th posterior of the 15th anterior, or a plateau shape, blunted at its two ends.
ARCM: median retro-capital support
The ARCM focuses on unloading the middle metatarsal heads. This support is used to redistribute forces at the corresponding necks and shafts, thereby reducing pressures and preventing forefoot collapse.
Limits and reliefs of the ARCM:
- Anterior: Forms a convex curve forward, at the level of M2, M3, and M4.
- Posterior: Located halfway between the medial and lateral Lisfranc landmarks.
- Lateral: Slightly convex lateral curved line, extending slightly into the 4th intermetatarsal space.
- Medial: Curved line convex medially, extending slightly into the 1st intermetatarsal space.
The ARCM can also present two types of relief: a dorsal convexity with a medial summit or a blunt plateau at its ends. This type of support is crucial to stabilize the metatarsals and prevent the metatarsals from coming together.
The ARCI, ARCE, and ARCM retrocapital supports play a fundamental role in the management of foot pathologies, particularly those involving the metatarsals. By understanding their specific indications and characteristics, podiatrists can offer personalized solutions that meet the particular needs of each patient. If you have any questions or experiences to share about the use of these supports, please feel free to leave them in the comments. Your participation contributes to enriching this discussion and helping other professionals and patients better understand these essential concepts.
