HTR polymer facial implants: a five-year clinical experience

Is polymethylmethacrylate reliable and practical in full-thickness cranial defect reconstructions?

OBJECTIVE

The study aimed to evaluate the success of polymethylmethacrylate cranioplasty combined with various soft tissue coverage techniques in repairing full-thickness cranial defects, to compare our results with similar studies published before, and to describe a simple method of implant premolding.

METHODS

A total of 17 patients who had cranial defects due to various etiologies underwent polymethylmethacrylate cranioplasty. In 10 patients, the implant premolding method was applied. The soft tissue coverage was obtained by primary closure, local flaps, or free flaps.

RESULTS

The follow-up period ranged from 36 hours to 5 years. Only 1 implant became exposed among the 17 patients. One patient died 36 hours after the surgery because of myocardial infarction. The remaining 15 patients had no early or late postoperative complications. Good contour restoration and stable reconstruction of the calvarial defects were realized, and a successful combination of various soft tissue coverage techniques was achieved.

CONCLUSIONS

We concluded that polymethylmethacrylate was a cheap and durable material, useful in full-thickness calvarial defect reconstructions. It can be combined with any soft tissue coverage techniques except skin grafting. In most cases, the simple premolding methods are useful for both defect matching and preventing tissue damage due to exothermic reaction of the material.

Is cranial reconstruction with a hard-tissue replacement patient-matched implant as safe as previously reported? A 3-year experience and review of the literature

PURPOSE

This study aimed to verify the low complication rates (0% to 11%) previously reported in cranial reconstruction using hard-tissue replacement patient-matched implant (HTR-PMI).

PATIENTS AND METHODS

A 3-year multidisciplinary experience involving 21 patients undergoing HTR-PMI reconstruction of large cranial defects was reviewed. Complications were defined as implant exposure, implant infection, or soft-tissue infection.

RESULTS

A statistically higher rate of complications was observed, compared with previous series (P= .043). We also determined whether previous bone infection, a history of diabetes, or smoking were risk factors for the development of complications. Diabetes, smoking, and pre-existing bone/implant infections were not significant risk factors for HTR-PMI failure. The higher rate of complications can be partially attributed to a diverse and complicated patient population, with multiple comorbid conditions and various indications for HTR-PMI reconstruction. In particular, decompressive craniectomies in trauma patients can be risky indications for the use of HTR-PMI.

CONCLUSION

Larger studies are suggested to verify our findings.

Long-Lasting and Permanent Fillers: Biomaterial Influence over Host Tissue Response

BACKGROUND

The purpose of this study was to attempt to understand why some injectable fillers produce frequent ill effects and some do not, by reviewing the available agents and analyzing them through the knowledge of biomaterial studies, which show clearly what type of reactions can be expected according to the chemical used.

METHODS

A study of long-lasting and permanent fillers was performed in an attempt to understand the specific reactions induced by each agent. Agents were then compared with manufacturers' allegations and published data on complications.

RESULTS

All the available products have a potential for complications. However, the difference between the normal healing process and true inflammatory granuloma must be established. For a volume effect, the implant, although deep, should induce the smallest inflammatory reaction, to avoid any long-term side effects. Particulate implants with porous or irregular surfaces are potentially more reactive than spherical, smooth-surface particles. Gels and oils have a potential for fragmentation, and each droplet will start a new inflammatory phase. For a superficial treatment, is seems better to use a "passive" filler, which should have no inflammatory reaction. The problem remains for combined indications: volume and smoothing, deep and superficial. After hyaluronic acid injections in areas previously treated with a nonresorbable agent, severe inflammatory granulomas have appeared, and it is not possible to state whether they are attributable to the new product, even a resorbable one, or to reactivation of the sleeping reaction from the previous implant.

CONCLUSION

There is an obvious need for serious, precise, and objective studies on most of the available fillers, which have not been properly scientifically studied on human skin.

Augmentation Mentoplasty Using a Custom-Design Wire Cage

Mentoplasty is often a complimentary procedure to rhinoplasty. At least 25% of all rhinoplasty patients may need a chin implant to balance facial features better. Augmentation mentoplasty using alloplastic implants such as silicone, rubber, or other materials provides a simple approach to the treatment of the hypoplastic chin. Although these types of implants are readily available in developed countries, there are parts of the world where they are unavailable or quite expensive. The authors have developed a chin implant made of wire that is available throughout the world and is custom designed to the mentum of the patient after a cephalometric evaluation. This technique has been used in 125 patients along with rhinoplasty over the last 20 years at our institution. In an initial series of 8 patients, the prosthesis became displaced and was removed in 2 patients. Since then, a new radiographic technique has been developed to demonstrate the shape of the mentum before surgery and new bone formation after surgery. By using this special radiographic technique, it was possible to detect four types of mentum before surgery and to construct a custom-design wire cage according to this shape. The prosthesis is constructed by an orthodontist according to the cephalometric measurements and shape of the mentum. By using the buccal approach, a pocket is prepared subperiosteally and a wire cage is inserted. In the last 20 cases, the wire cage was filled with diced cartilage wrapped with Surgicel. The results were esthetically satisfactory in most patients. After the shape of the wire prosthesis was modified to conform to the shape of the underlying bone better, no displacement of the prosthesis has been experienced. In 3 patients, it was necessary to remove the prosthesis when new tissue formation began to fill the prosthesis. These specimens were examined histologically, and the regenerating tissue was found to be connective tissue with a thin layer of bone formation. Most patients could be followed up for only 3 to 12 years. In all patients, the results have been consistent and the procedure has been safe.

Cranial reconstruction with computer-generated hard-tissue replacement patient-matched implants: indications, surgical technique, and long-term follow-up

The aim of this clinical study was to evaluate the effectiveness and safety of using computer-generated alloplastic (hard-tissue replacement) implants for the reconstruction of large defects of the upper craniofacial region. Fourteen patients who had large (> 150 cm2) preexisting defects of the cranium or cranio-orbital region underwent surgical reconstruction. Preoperatively, a three-dimensional computed tomographic scan was obtained from which an anatomic model was fabricated. The defect in the model was then used to create an alloplastic (hard tissue-replacement polymer) implant for reconstruction and surgical placement. At the time of surgery, the implant was secured into position with either metal or resorbable fixation. In cases where the frontal sinus was in proximity to the implant, the frontal sinus was either cranialized and covered with a pericranial flap or obliterated with hydroxyapatite cement. In cases that had been previously irradiated or infected, wide bony debridement and coverage with a vascularized muscle was initially performed, followed by implant reconstruction 6 months later. All implants fit easily into the bone defects, and only four (29 percent) required some minor adjustments to complete the fit. All patients healed uneventfully. With a minimum of 1 year follow-up (average, 3 years) in all cases, excellent contours have been maintained and all patients have remained infection-free. In large cranial defects, custom implants fabricated from porous, hydrophilic hard-tissue replacement polymer provide an exacting anatomic fit and a solid stable reconstruction. This method of reconstruction in these defects is rapid and exact, and significantly reduces operative time. Critical attention must be paid, however, to management of the frontal sinus and preexisting bone infection and the quality of the overlying soft-tissue cover.

Genioplasty: a case for advancement osteotomy

Despite personal preferences and training background that may influence the choice of which genioplasty technique to use, the osteoplastic technique has a better patient satisfaction rate (albeit slight), better soft tissue predictability, and less detrimental postoperative complications when compared with alloplastic augmentation of the chin. In addition, the osteoplastic technique is a more versatile procedure that can be used to correct any type of chin deformity and it has less of the limitations and contraindications associated with the alloplastic techniques.

Complications and toxicities of implantable biomaterials used in facial reconstructive and aesthetic surgery: a comprehensive review of the literature

The use of implantable biomaterials has become an integral part of aesthetic and reconstructive surgery of the face. Metals are used for fracture fixation devices, whereas polymers are used primarily for bone or soft-tissue substitution. This review of the scientific literature examines the risks and complications of these materials. First, we present an overview of commonly used materials. Second, we address general considerations of toxicity relevant to all biomaterials. Third, we present data from a large number of clinical series on the incidence of complications for individual materials used in specific applications.