The histologic host response to liquid silicone injections for prevention of pressure-related ulcers of the foot: a 38-year study

A Step in the Right Direction: A Prospective Randomized, Controlled Crossover Trial of Autologous Fat Grafting for Rejuvenation of the Heel

BACKGROUND

The shock-absorbing soft tissues of the heel are composed of dermis and specialized fat pads. Heel fat pad atrophy is common and can be painful and debilitating. In our previous work, autologous fat grafting was effective for treating pain from forefoot fat pad atrophy.

OBJECTIVES

The authors hypothesized that autologous fat grafting to the heel would relieve pain and improve function in patients with heel fat pad atrophy.

METHODS

Patients with heel fat pad atrophy and associated pain were recruited and randomized into 2 groups. Group 1 received autologous fat grafting on enrollment and was followed for 2 years. Group 2 received offloading and activity modification for 1 year, then crossed over, underwent autologous fat grafting, and was followed for 1 year afterward. Outcome measures included ultrasound-measured fat pad and dermal thickness; pedobarograph-measured foot pressures and forces; and patient-reported outcomes as measured by the Manchester Foot Pain and Disability Index.

RESULTS

Thirteen patients met the inclusion criteria and completed the study. Seven (12 affected feet) were randomized into Group 1; and 6 (9 affected feet) were randomized into Group 2. The average age was 55 years and BMI was 30.5 kg/m2. Demographics did not significantly differ between groups. Heel fat pad thickness increased after autologous fat grafting but returned to baseline at 6 months. However, autologous fat grafting increased dermal thickness significantly and also increased fat pad thickness under a compressive load compared with controls at 6 and 12 months. Foot pain, function, and appearance were also significantly improved compared with controls at 6 and 12 months.

CONCLUSIONS

Autologous fat grafting improved patient-reported foot pain, function, and appearance and may rejuvenate local soft tissues in patients with heel fat pad atrophy.

LEVEL OF EVIDENCE: 3

Ten-Year and Beyond Follow-up After Treatment With Highly Purified Liquid-Injectable Silicone for HIV-Associated Facial Lipoatrophy: A Report of 164 Patients

BACKGROUND

Highly purified liquid-injectable silicone (LIS) has been established as a permanent agent for off-label correction of HIV-associated facial lipoatrophy (HIV-FLA). However, controversy exists about long-term safety.

OBJECTIVE

To establish the safety and efficacy at 10 years or greater of LIS for HIV-FLA.

METHODS

Patients from 3 practices with 10-year or greater in-person office follow-up were analyzed to determine the number of LIS treatments and total volume required to achieve optimal correction. The nature of any treated adverse events was noted.

RESULTS

One hundred sixty-four patients had 10-year or greater in-office follow-up. All subjects maintained long-term correction with an average of 9 treatments, average of 1.56 mL per treatment, and an average total of 14.1 mL. Two patients had severe adverse events manifesting as temporary facial edema. Four patients experienced mild-to-moderate excess fibroplasia presenting as perceived overcorrection, and 6 patients had nondisfiguring subcutaneous firmness. All adverse events were successfully treatable, mostly with intralesional 5-fluorouracil and triamcinolone.

CONCLUSION

Liquid-injectable silicone is an effective long-term treatment option for HIV-FLA. When injected in small quantities with the microdroplet serial puncture technique at monthly or greater intervals, optimal correction appears durable for more than 10 years. Adverse events consisted mostly of excess fibroplasia and were treatable.

Use of hyaluronic acid gel filler versus sterile water in the treatment of intractable plantar keratomas: a pilot study

BACKGROUND

Intractable plantar keratoma is a common concern in the podiatric medical office. Different treatment options are available, ranging from trimming and padding to surgery. We sought to investigate the use of hyaluronic acid gel injections as a possible minimally invasive alternative in the treatment of intractable plantar keratomas.

METHODS

Seventeen patients with intractable plantar keratomas were randomly assigned to receive a hyaluronic acid gel injection or a sterile water injection at the site of a previously trimmed plantar lesion.

RESULTS

There was no significant difference between the two groups in the evaluation of pain and function at 12 weeks, but both groups showed a clinically relevant improvement. No significant change was observed in plantar tissue thickness in both groups. A minor adverse reaction was seen in the hyaluronic acid group.

CONCLUSIONS

The use of a hyaluronic acid gel injection at the site of a trimmed intractable plantar keratoma did not seem more effective than the use of a sterile water injection. Sterile water injections seemed safe and efficient in reducing pain associated with plantar keratomas. Further investigations should concentrate on whether these results are reproducible in a larger sample and on the most effective sequence of treatment.

Histopathologic response to highly purified liquid silicone injected intradermally in rats' skin

BACKGROUND

This study aimed to assess and compare the tissue response to small- and large-volume injections of pure liquid silicone in rats.

METHODS

The study used 25 Sprague-Dawley rats. Two different injection sites were determined for a single rat, and 5000 centistoke liquid silicone was injected subdermally using 0.2-0.3 ml (small volume) and 1 ml (large volume) injections. After the injections, 15 animals were killed at 4 weeks and 10 animals at 10 weeks. Tissue responses were evaluated under a light microscope.

RESULTS

At week 4, the numbers of lymphocytes and neutrophils were higher in the small-volume injection group. At week 10, the number of neutrophils decreased, and the numbers of macrophages and foreign body giant cells increased in the small-volume injection group, whereas the intensity and type of infiltrate in the large-volume injection group did not change significantly. The thickness of the fibrous capsule was greater in large-volume injection group at weeks 4 and 10. The thickness of the fibrous capsule did not change significantly in either group through time.

CONCLUSIONS

Purified high-density liquid injectable silicone causes a low-grade and well-tolerated inflammatory response during the long term and can be used when given as small-volume injections.

Liquid silicone to mitigate plantar pedal pressure: a literature review

Disruption of the body's plantar fat pad can occur as a result of one of three mechanisms: simple fat pad atrophy associated with age-related degeneration, steroid use, or collagen vascular disease. Actual or relative displacement in to the underlying osseous prominences may be seen in association with structural deformity of the foot. Disease states such as diabetes may alter the normal structural integrity of soft tissues through nonenzymatic glycation leading to increased stiffness and thus reduced attenuating capacity. Fat pad atrophy, regardless of the cause, is often associated with substantial emotional, physical, productivity, and financial losses. In situations where the patient is sensate, the resultant skin on bone situation is extremely painful, especially when walking.

The characterization and optimization of injectable silicone resin particles in conjunction with dermal fibroblasts and growth factors: an in vitro study

Minimally invasive subdermal injection of liquid silicone has been used clinically to augment the soft tissue of the foot to mitigate high pressures that cause diabetic foot ulcers. However, implant migration has been a clinical issue. The objective of this study was to assess the effects of three specific concentrations of silicone resin particles (12 mum average diameter) in conjunction with either platelet-derived growth factor (PDGF-BB) or basic fibroblast growth factor (bFGF) on fibroblast cell proliferation, collagen synthesis, cell morphology, and migration through in vitro assays and a monolayer scratch wound model. PDGF and bFGF enhanced the proliferation of fibroblasts 5.7-fold and fivefold, respectively, while the addition of silicone particles had no significant effect on proliferation. Collagen production was increased approximately twofold with the addition of bFGF and the medium concentration of particles over bFGF without particles and the PDGF groups. The addition of silicone particles had no significant effect on collagen production compared with control groups without particles. Fibroblast migration was enhanced by the addition of both PDGF and bFGF compared to controls, although slower scratch wound closure rates were observed in the presence of particles compared to controls without particles. Cell morphology suggested that particles induced cellular aggregation encircling silicone particles postwounding as well as migration into the wound area. These results suggest that silicone particles in combination with a growth factor might enhance fibroblast aggregation and implant stability, and could promote connective tissue ingrowth and implant encapsulation in the soft tissue of the diabetic foot.

Augmentation of atrophic plantar soft tissue with an acellular dermal allograft: a series review

Treatment of plantar fat pad migration and atrophy has caused concern for decades. Patients can present with pain, callus formation, or ulceration. The purpose of this article is to review the results of a consecutive series of patients treated for fat pad atrophy of the plantar foot, using a minimally invasive implantation of an acellular human dermal allograft as a tissue augmentation. This material was chosen for the fat pad supplementation because of previous reports of success in tendon and ligament augmentation, wound healing, and interpositional arthroplasty.

Liquid Injectable Silicone: A Review of Its History, Immunology, Technical Considerations, Complications, and Potential

For over five decades, liquid injectable silicone has been used for soft-tissue augmentation. Its use has engendered polarized reactions from the public and from physicians. Adherents of this product tout its inert chemical structure, ease of use, and low cost. Opponents of silicone cite the many reports of complications, including granulomas, pneumonitis, and disfiguring nodules that are usually the result of large-volume injection and/or industrial grade or adulterated material. Unfortunately, as recently as 2006, reports in The New England Journal of Medicine and The New York Times failed to distinguish between the use of medical grade silicone injected by physicians trained in the microdroplet technique and the use of large volumes of industrial grade products injected by unlicensed or unskilled practitioners. This review separates these two markedly different procedures. In addition, it provides an overview of the chemical structure of liquid injectable silicone, the immunology of silicone reactions within the body, treatment for cosmetic improvement including human immunodeficiency virus lipoatrophy, technical considerations for its injection, complications seen following injections, and some considerations of the future for silicone soft-tissue augmentation.

Injectable Silicone and the Foot: A 41-Year Clinical and Histologic History

BACKGROUND

Since 1964, the author has investigated injectable liquid silicone as a soft tissue substitute for the loss of plantar fat. This form of fatty tissue depletion over the sole is closely linked to a common painful weight-bearing foot disorder, metatarsalgia, and to painless diabetic foot ulcers.

OBJECTIVES

To present the history of injectable silicone, corporate interest, individuals who helped pursue approval, its misuses, and events that have delayed its availability.

MATERIALS AND METHODS

Dow Corning Corporation's 360 Medical Fluid of 350 centistoke was injected beneath corns and calluses in 1585 patients. Diabetic neuropathic foot ulcers were injected after healing in an effort to prevent their recurrence. Surgical and postmortem specimens were gathered for histologic analysis.

RESULTS

There was no evidence of significant adverse response in long-term clinical follow-up. Silicone specimens studied by two departments of pathology found no inflammation, infection, allergy, or granulomas.

CONCLUSIONS

Medical Fluid silicone appears to be safe, effective, and stable biomaterial for treating weight-bearing loss of plantar fat. Trademarked PodiSil (Richard-James Inc., Peabody, MA, USA), a 350-centistoke injectable silicone has been approved for marketing in Europe for the prevention of diabetic foot ulcers.