Despite decades of research, the exact cause of hairdressing contracture in silicone breast implants remains unclear, and many plastic surgeons struggle to explain this phenomenon. Often, hairstyle contracture is presented as a typical foreign body reaction, but the delayed manifestation . . . sometimes years after implantation . . indicates a more complex pathological process.
Hairdressing contracture occurs when the body forms a fibrous hairstyle around the implant that hardens and contracts, causing pain, aesthetic distortion and often explantation. Approximately 25% of the implants are removed due to this complication, which may occur shortly after implantation or after years. This is not a simple physiological reaction, but a chronic inflammation process, possibly driven by degradation of implant materials.
An underexposed factor is pyrogenic silica, a filler that accounts for 21,77% of the implant envelope and improves its strength and elasticity. Many plastic surgeons are not aware of the presence of pyrogenic silica, let alone its possible role in complications. Pyrogenic silica particles, which are not fully bound in the polydimethyl disregarded (PDMS) matrix, may migrate to aging, silicone bleed or ruptured.
Thebound rubber layer, in which PDMS anchors pyrogenic silica particles via adsorption and hydrogen bridges between silica particles, may weaken by oxidative or mechanical degradation. This can cause agglomeration of silica particles, which weakens the implant envelope and promotes microfractures, as suggested by a 16% thinner envelope after about 4 years (Bodin, 2015). This allows silica particles to loosen, which further impairs mechanical stability and can stimulate chronic inflammation.
These free silica particles can activate immune cells, especially macrophages, via signal paths such as Toll-like receptor (TLR) signaling, possibly via TLR4. This may lead to the release of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α), which stimulate fibroblasts to produce collagen, which may contribute to fibrosis and hairstyle hardening. In addition, reactive silanol groups (nearly free silanols, NFS) may be exposed to silica particles, normally masked by surface treatment, at degradation, as suggested by yellow discoloration of explanted implants. Research shows that pyrogenic silica can be as harmful to macrophages as crystalline silica, which is classified by the IARC as carcinogenic, which underlines the toxicity of NFS. Sustained macrophage activation can create a self-enhancing ignition cycle, which could explain the delayed nature of hairstyle contracture.
The clinical implications are significant: chronic inflammation, possibly caused by pyrogenic silica, may worsen local symptoms such as pain and distortion and may cause systemic symptoms such as fatigue or autoimmune symptoms, as reported in some patients with silicone implants (also called Breast Implant Illness). Recent literature, such as the IOM study Safety of Silicone Breast Implants (p. 68) and the work of DeGroot and Macosko, suggests that pyrogenic silica could be a key cause, a hypothesis requiring urgent further research.
To reduce complications such as hairdressing contracture, improvements are needed, such as more stable surface treatments to minimize NFS, more durable envelopes to prevent degradation, and targeted research into the toxicity of pyrogenic silica in implants. By addressing these risk derivatives, silicone implants can be made safer.
Technical support
Pyrogenic silica: A high-risk filler
The envelope of silicone breast implants consists of polydimethyl hindered (PDMS), reinforced with pyrogenic silica (21,27% of the envelope). Silicone improves strength and elasticity, but degradation can cause serious complications. It is often thought that amorphic silica in nanoform is less toxic, but research shows that pyrogenic silica can be as harmful to macrophages (immune cells) as crystalline silica, which can be caused by the IARC is classified as carcinogenic. This makes silica a worrying factor in implants, through two mechanisms: bound rubber and near free silanols (NFS).
Bound Rubber: The fragile basis of the envelope
Bound rubber is the layer of PDMS that is strongly attached to silica particles, leaving the envelope firm and elastic. Research, such as that of DeGroot and Macosko, emphasizes that a stable bound rubber layer anchors silica particles and prevents them migrating within the envelope. However, with aging this goes wrong:
- Degradation: Bodin (2015) found that the envelope became 16% thinner after 4.25 years, indicating weakening the PDMS matrix and bound rubber. This can cause microfractures, causing silica particles to loosen.
- Agglomeration: Untreated silica particles clump together (Filler Filler interactions), as recent studies show, which makes the envelope less homogeneous and introduces mechanical weakness.
- Effects: A weakened envelope increases the risk of gel bleaching and migration of silica particles, which activate macrophages and stimulate chronic inflammation, such as hairdressing contracture.
Nearly Free Silanols: A toxic threat
NFS are reactive silanol groups (Si-OH) on silica particles that, according to Pavan et al., causing inflammation and cell damage due to interactions with cell membranes. In implants NFS are normally masked by surface treatment (the " effect" with only 60% trimethylsilyl coverage), but degradation makes it active:
- Exposure: Yellow discoloration of explanted implants, as observed by Bodin, may indicate degradation of surface treatment, exposing NFS.
- High toxicity: Pyrogenic silica NFS cause chronic inflammation, such as granulomas, siliconomas, and hairstyle contracture, and possibly systemic symptoms such as Breast Implant Illness (BII).
- Cumulative impact: The late inset of hairstyle contracture suggests that continuous exposure to NFS, due to degradation and migration, makes the hairstyle pathological.
Disclaimer:
The information on this website is intended for informational purposes and is based on carefully collected scientific research. The topics and hypotheses discussed have not yet been widely recognised within the medical community. We are not doctors and do not give medical or legal advice. No rights can be derived from the content of this website. Stichting SVS accepts no liability for any consequences, damage, complaints or legal proceedings arising from the use of this information.
