Superficial retrocalcaneal bursae and nerves: From anatomy to ultrasound-guided procedures

Abstract

The pertinent literature widely describes ultrasound-guided procedures targeting the retrocalcaneal bursa and the tendon tissue to manage insertional Achilles tendinopathy. Synovial bursae and cutaneous nerves of the superficial retrocalcaneal pad are often overlooked pain generators and are poorly considered by clinicians and surgeons. A layer-by-layer dissection of the superficial soft tissues in the retrocalcaneal region of two fresh frozen cadavers was matched with historical anatomical tables of the textbook Traite d'Anatomie Topographique Avec Applications Médico-Chirurgicales (1909 by Testut and Jacob). An accurate and detailed description of the superficial retrocalcaneal pad with its synovial bursae and cutaneous nerves was provided. Cadaveric dissections confirmed the compartmentalized architecture of the superficial retrocalcaneal fat pad and its histological continuum with the superficial lamina of the crural fascia. Superficial synovial tissue islands have been demonstrated on the posterior aspect of the Achilles tendon in one cadaver and on the posterolateral surface of the tendon in the other one. Digitalization of the original anatomical tables of the textbook Traite d'Anatomie Topographique Avec Applications Médico-Chirurgicales (1909 by Testut and Jacob) showed five potential locations of the superficial calcaneal bursa and a superficial retrocalcaneal nerve plexus within the Achilles tendon-fat pad interface. In clinical practice, in addition to the previously described interventions regarding the retrocalcaneal bursa and the tendon tissue, ultrasound-guided procedures targeting the synovial and neural tissues of the superficial retrocalcaneal pad should be considered to optimize the management of insertional Achilles tendinopathy.

Keywords: Achilles tendon; injection; medial calcaneal nerve; sonography; sural nerve; synovial bursa.

FIGURE 1

Cadaveric anatomy of the superficial retrocalcaneal region–Sample 1. Cadaveric dissection shows multiple fibrous septae (black asterisks) within the superficial retrocalcaneal fat pad (sRFP) and a rounded synovial cavity (white arrowhead) between the skin (S) and the Achilles tendon. Dist, distal; Prox, proximal.

FIGURE 2

Cadaveric anatomy of the superficial retrocalcaneal region–Sample 2. Cadaveric dissection shows the histological continuum (black arrowhead) between the superficial lamina of the crural fascia (yellow arrowhead) and the superficial retrocalcaneal fat pad (sRFP). Using forceps, a small synovial cavity (white arrowhead) can be observed between the sRFP and the dorsal surface of the Achilles tendon (AT) along the midline. Dist, distal; S, skin; Prox, proximal.

FIGURE 3

Schematic drawings of the superficial retrocalcaneal region. Five superficial calcaneal bursae (green) have been described along the posterior surface of the Achilles tendon (white) and calcaneus (A). Within the superficial retrocalcaneal fat pad (sRFP), there is a nerve plexus originating from the anastomosis of the distal branches of the medial calcaneal (MCN) and sural nerves (SN) (B). subc, subcutaneous fat tissue; sCF, superficial lamina of the crural fascia (schematic drawings represent digitalization of the original anatomical tables of Testut and Jacob. Traite d'anatomie topographique avec applications médico‐chirurgicales, 1909. Tables 697, 700).

FIGURE 4

Sonographic pattern of superficial retrocalcaneal bursitis. Longitudinal scans (A, B) show a hypertrophic superficial retrocalcaneal bursa (b) presenting as a hypoechoic ovoidal mass between the superficial retrocalcaneal fat pad (sRFP) and the more distal fibers of the Achilles tendon (AT). Transverse scans (C, D) show hyperechoic fibrotic septae (void arrowhead) as multiple bursal compartments (white asterisks).