Anatomical variants of the medioplantar oblique ligament and inferoplantar longitudinal ligament: an MRI study

Anatomical Description of the Spring Ligament Articular Facet

Background

The spring ligament fibrocartilaginous complex (SLFC), which is essential for stabilizing the medial longitudinal arch, features a little-explored fibrocartilaginous facet within its superomedial aspect, articulating with the talar head. This research aimed to provide a detailed anatomical description of this facet, designated as the spring ligament articular facet (SLAF).

Methods

Nine normally aligned cadaveric lower limbs were dissected, approaching the SLFC from a superior direction. Following talus disarticulation, high-resolution images of the ligament complex were captured and analyzed. ImageJ software was used to determine the areas and dimensions of the superomedial calcaneonavicular (SMCN) spring and SLAF.

Results

The fibrocartilage facet exhibited a trapezoid shape in all specimens. The mean area for SMCN spring was 280.39 mm², and for SLAF, it was 200 mm². The proximal-to-distal length for SLAF averaged 11.78 mm at its longest and 5.34 mm at its shortest. Attachment of the SLAF to the calcaneum and the navicular showed robust fibrous structures, with average measurements of 3.75 and 1.75 mm at the medial and lateral calcaneal margins, and 2.75 and 2.98 mm at the medial and lateral navicular margins, respectively.

Conclusion

This study clearly delineated the individual structural components of the SLFC articulating with the talar head and detailed its dimensions, emphasizing the need for more specific anatomical terminology that respects the intricate anatomy of the SLFC.

Level of Evidence

Level III, descriptive study.

Coxa pedis: can calcaneal pronation angle be considered a predictive sign of medial plantar arch overload?

PURPOSE

To assess whether a correlation between the calcaneal pronation angle and the presence of internal plantar arch overload signs (such as upper-medial spring ligament lesion, posterior tibial tendon tenosynovitis, etc.) could lead to a better understanding of coxa pedis pathology.

MATERIAL AND METHODS

One hundred ankle MRIs of consecutive patients were retrospectively reviewed measuring the calcaneal pronation angle and either the presence or absence of internal plantar arch overload signs. Next, the association of overload signs with increasing pronation angle was evaluated to establish a cut-off point beyond which coxa pedis pathology could be defined.

RESULTS

The tibial-calcaneal angle values in patients with and without effusion proved to be significantly different (p < 0.0001). The tibial-calcaneal angle values in patients with and without oedema also demonstrated a significant difference (p < 0.0056). Regarding posterior tibial tendon, a significant difference was found between the two groups (p < 0.0001). For plantar fascia enthesopathy, the result was borderline significant (p < 0.054). A linear correlation was found between the value of pronation angle and the extent of spring ligament injury (p < 0.0001). In contrast, no correlation with age was found.

CONCLUSION

In conclusion, the literature associates medial longitudinal plantar arch overload with posterior tibial tendinopathy and spring ligament complex injuries. Our data show that both injuries are highly correlated with increased calcaneal pronation angle, which could be considered a predictive sign of internal plantar arch overload, prior to the development of the associated signs.

Normal and Diseased Imaging: Ultrasound/MRI

The lesser metatarsophalangeal joint plantar plate and calcaneonavicular (spring) ligament are highly specialized soft tissue structures within the foot, consisting partly of fibrocartilage and capable of withstanding high compressive and tensile loads. Preoperative advanced imaging, in the form of point-of-care ultrasound and MRI, has become indispensable for surgeons hoping to confirm, quantify, and better localize injuries to these structures before surgery. This article describes the technical considerations of ultrasound and MRI and provides examples of the normal and abnormal appearances of these structures. The pros and cons of each imaging modality are also discussed.