In the field of podiatry, retrocapital support concepts are essential for understanding the solutions offered for various foot pathologies, particularly those related to the metatarsals. In this article, we will explore the three types of retrocapital supports: ARCI (internal retrocapital support), ARCE (external retrocapital support), and ARCM (medial retrocapital support). Each type of support has specific indications, and understanding them is crucial for optimal podiatric care.
What is retrocapital support?
Retrocapital support is a support zone located behind the metatarsal heads. These supports are used to redistribute pressure forces on the forefoot, thus preventing pain and deformities caused by excessive overload on certain areas. The objective is to protect by offloading the metatarsal heads and correcting certain forefoot anomalies.
ARCI: Internal retrocapital support
ARCI focuses on offloading the medial metatarsal heads (M1, M2, M3). This support is particularly useful when seeking to relieve by reducing pressure on the inside of the foot, without correcting a valgus foot.
Limits and reliefs of ARCI:
- Anterior: Follows the retrocapital line of M1, M2, and M3, forming an anterior concave curve at the first metatarsal neck.
- Posterior: A posterior concave line, it joins the internal Lisfranc landmark, medially.
- Lateral: A curved line with lateral convexity that joins the antero-lateral limit to the postero-lateral limit.
- Medial: A straight line; this limit joins the antero-medial limit to the postero-medial limit with a slight overhang to adapt to the shoe.
In terms of reliefs, ARCI has an "aerofoil" shape, with a summit located at the junction of the posterior 45th and anterior 15th. This type of support is designed to offload the medial metatarsal heads and reduce pressure on this area.
ARCE: External retrocapital support
ARCE is intended to offload the lateral metatarsal heads (M4, M5). This support is particularly effective in combating excessive forefoot supination, especially if the material used is sufficiently rigid.
Limits and reliefs of ARCE:
- Anterior: Follows the neck line of M2, M3, M4, and M5.
- Posterior: Confused with the lateral/external half of the Lisfranc joint line.
- Lateral: Rectilinear, it slightly overhangs the primary insole, unable to project inside it.
- Medial: Curved with slight medial convexity, it joins the anterior and posterior limits.
For reliefs, ARCE can present two possibilities: an "aerofoil" shape with a summit located at the junction of the posterior 45th and anterior 15th, or a plateau shape, blunted at both ends.
ARCM: Medial retrocapital support
ARCM focuses on offloading the middle metatarsal heads. This support is used to redistribute forces at the corresponding necks and diaphyses, thus reducing pressure and preventing forefoot collapse.
Limits and reliefs of ARCM:
- Anterior: Forms an anterior convex curve at M2, M3, and M4.
- Posterior: Located halfway between the internal and external Lisfranc landmarks.
- Lateral: A slightly laterally convex curved line, slightly overhanging into the 4th inter-metatarsal space.
- Medial: A medially convex curved line, slightly overhanging into the 1st inter-metatarsal space.
ARCM can also present two types of reliefs: dorsal convexity with a medial summit or a plateau blunted at its ends. This type of support is crucial for stabilizing the metatarsals and preventing metatarsal approximation.
The ARCI, ARCE, and ARCM retrocapital supports play a fundamental role in managing 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 regarding the use of these supports, feel free to leave them in the comments. Your participation enriches this discussion and helps other professionals and patients better understand these essential concepts.
