Soft-Tissue Augmentation With Calcium Hydroxylapatite

Abstract

To evaluate histologically the extent and character of tissue in-growth after injection of calcium hydroxylapatite for soft-tissue augmentation. Methods: Prospective case series of 8 patients from a private facial plastic surgery practice. Each patient was injected subdermally between the dermis and the subcutaneous fat with 0.1 mL of calcium hydroxylapatite in the superior postauricular sulcus. One month later, 2 patients underwent excision of the injected material, which was submitted for routine histological evaluation by an independent dermatopathologist. The material was stained with hematoxylin-eosin and trichrome to assess new collagen deposition. One of these patients was reinjected in the contralateral postauricular sulcus. Six and 18 months after injection, 3 patients and 1 patient, respectively, underwent excision of the injected material, which was then submitted for histological evaluation of the degree and character of tissue in-growth and tissue reaction. Results: The calcium hydroxylapatite particles were found to be surrounded by a lymphocytic infiltrate with multiple foreign body giant cells. There was no evidence of new collagen formation, migration, or heterotopic bone growth. Two patients were lost to follow-up. Conclusions: Calcium hydroxylapatite is a stable softtissue filler that stimulates an immune response with lymphocytic infiltration and foreign body giant cell formation. We found no evidence of new collagen formation 1, 6, or 18 months after injection.

Microscopic and ultrastructural evidences in human skin following calcium hydroxylapatite filler treatment

“…In this way, a slow dispersion of the microgranular content in the close extracellular matrix environment, freely into the ground substance and/or between the collagen fibres, would permit a more homogeneous distribution of microgranules. These observations do not agree with some previous research works, reporting lymphocytic infiltrate associated with giant cells engulfing spherules, without migration of the implanted material, and supporting a phagocytotic mechanism [15, 16]. …”

“…While some authors were supporting a stimulatory induction to form new collagen as the gel carrier is metabolized [3, 15], others did not give evidence of new collagen deposition, “may be due to the small size of examined samples”, as stated by the authors here cited [16]. …”

Aesthetic dermatology: What's new, what's true?

“…The temporary increase in collagens I and III does however not explain the long‐term improvement obtained by CaHA as mature collagen incorporated into extracellular matrix has a half‐life of >200 years in bone, cartilage, and tendons and of about 15 years in skin (Heinemeier, Schjerling, Heinemeier, Magnusson, & Kjaer, ; Libby, Berger, Mead, Alexander, & Ross, ; Verzijl et al, ). Indeed, the study of Holzapfel, Mangat, and Barron () could not find any evidence of mature collagen formation by CaHA (Holzapfel et al, ). Another investigation using light and electron microsopies described a well‐represented Golgi apparatus in fibroblasts in vicinity to CaHA (Zerbinati, D'Este, Parodi, & Calligaro, ).…”

Complications and their management

“…As outlined previously, if nodules do occur, they can be treated in part with intralesional injection and/or surgical excision. Theoretical concerns of bone stimulation following CaHA injection have been raised, but to date no studies have shown this theory to be true ( 167 ). Nonetheless, it is still recommended that this fi ller not come in direct contact with bone when injecting into the preperiosteal plane ( 5 ).…”