Novel Investigation of the Deep Band of the Lateral Plantar Aponeurosis and Its Relationship With the Lateral Plantar Nerve.

BACKGROUND: We describe a thick fascial band arising from the medial aspect of the lateral plantar aponeurosis diving deep into the forefoot crossing over a branch of the lateral plantar nerve. Because a review of current literature resulted in limited and outdated sources, we sought to first determine the frequency of this fascial band and the location where it crosses the lateral plantar nerve and, second, discuss the clinical applications these anatomical findings could have. METHODS: 50 pairs of cadaveric feet (n = 100) were dissected to investigate for presence of the fascial band and its interaction with the lateral plantar nerve. Images were taken of each foot with the fascial band. ImageJ was used to take 2 measurements assessing the relationship of the tuberosity of the base of the fifth metatarsal to where the nerve crossed deep to the fascial band. RESULTS: Overall, 38% of the feet possessed the fascial band. It was found unilaterally in 10 pairs and bilaterally in 14 pairs. On average, the point at which the lateral plantar nerve passed deep to the fascial band was 2.0 cm medial and 1.7 cm anterior to the tuberosity of the base of the fifth metatarsal. CONCLUSION: When present, the deep band of the lateral plantar aponeurosis (PA) was consistently found to be crossing the lateral plantar nerve. The discovery of the location where this most commonly occurs has not been previously reported and adds an interesting dimension that elevates an anatomical study to one that has clinical potential. CLINICAL RELEVANCE: The established target zone gives a precise location for where the relationship between the deep band of the lateral PA and the lateral plantar nerve exists when evaluating the foot. The target zone provides a potential springboard for future investigations concerning said relationship clinically.

Characterization of Brown Adipose-Like Tissue in Trauma-Induced Heterotopic Ossification in Humans.

Heterotopic ossification (HO), the abnormal formation of bone within soft tissues, is a major complication after severe trauma or amputation. Transient brown adipocytes have been shown to be a critical regulator of this process in a mouse model of HO. In this study, we evaluated the presence of brown fat within human HO lesions. Most of the excised tissue samples displayed histological characteristics of bone, fibroproliferative cells, blood vessels, and adipose tissue. Immunohistochemical analysis revealed extensive expression of uncoupling protein 1 (UCP1), a definitive marker of brown adipocytes, within HO-containing tissues but not normal tissues. As seen in the brown adipocytes observed during HO in the mouse, these UCP1+ cells also expressed the peroxisome proliferator-activated receptor γ coactivator 1α. However, further characterization showed these cells, like their mouse counterparts, did not express PR domain containing protein 16, a key factor present in brown adipocytes found in depots. Nor did they express factors present in beige adipocytes. These results identify a population of UCP1+ cells within human tissue undergoing HO that do not entirely resemble either classic brown or beige adipocytes, but rather a specialized form of brown adipocyte-like cells, which have a unique function. These cells may offer a new target to prevent this unwanted bone.