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PubMedDate not supplied

Observations on an experimental expansile electrode for use in cochlear implantation.

Cochlear implants in children must be designed to allow for a child's growth and maturation. An experimental animal study was performed to document the influence of head growth on a prototype expansile electrode system. Seven kittens were implanted with a stimulated electrode which had been coiled to allow for a two-to-one expansion in length. Head growth was monitored both by direct skull measurements and by serial radiography. The animals were sacrificed when they had reached maturity and the implanted devices were studied. When implanted in subcutaneous tissue, the coils became encased in fibrous tissue, while within air-containing spaces, such as the bulla, they distended freely. This suggested that a route which maximized the amount of air-containing space traversed by an electrode should be the preferred route for a cochlear implant in children.

Animals↗
PubMed2000

Sutural expansion osteogenesis for management of the bony-tissue defect in cleft palate repair: experimental studies in dogs.

A series of experimental studies on sutural expansion osteogenesis for management of the bony-tissue defect in cleft palate repair was performed between 1995 and 1997. Forty-five young dogs in weaning were used in four experiments that were divided into two parts. Part I probed the possibility of closing the surgically constructed hard palate cleft not only with mucoperiosteum but also with bony tissue by the technique of sutural expansion of lateral palatine sutures. Part II explored the possibility of pushing the palatine bone posteriorly and advancing the maxillary segment anteriorly by transverse palatine suture expansion. In Part I, a ring-shaped suture expander made of nickel-titanium shape memory alloy was used to expand the lateral suture of palatine bones. Expansion forces of 200 G, 360 G, and 480 G were used for the first experiment. A force of 360 G was chosen for two other experiments; this force is equivalent to the distraction rate of 0.5 mm per day of a jackscrew device. The ring-shaped suture expander was opened and its two feet were fixed in the medial sides of residual horizontal plates of the palatine bones immediately after a hard palate cleft was constructed surgically under endotracheal general anesthesia. At the eighth postoperative day, under the traction of 360 G, the two sides of the 8-mm-wide hard palate cleft were brought into contact with each other, and 8 or 9 days later the closed palatal cleft had healed completely with mucosal tissue. This experiment was repeated twice and yielded the same results. Sutural expansion osteogenesis was evaluated physically, fluorescently, histologically, and ultrastructurally to examine the deposition of the regenerated bone in the suture areas. Additionally, the influence of sutural expansion osteogenesis of the palatal bones on other facial bones was also studied cephalometrically. In Part II, a bow-shaped suture expander made of nickel-titanium shape memory alloy was applied to expand either the left or the right side of the transverse palatal suture of each of the experimental dogs. At the postoperative week 4 to 6, the maxillary segment was moved forward 5 to 6 mm on the expanded side, and the palatal bone was pushed backward 5 mm. The changes of bone position were assessed radiographically and cephalometrically. Tissue response of circum-maxillary sutures was examined histologically. These experiments led to the following conclusions: (1) Bony closure of the surgically constructed hard palate cleft with a ring-shaped suture expander made of nickel-titanium shape memory alloy is possible. (2) Anterior advancement of the maxillary segment and posterior lengthening of the hard palate using a bow-shaped suture expander made of nickel-titanium shape memory alloy applied at the palatomaxillary suture (transverse palatal suture) of the hard palate are also possible. Thus, in humans, a new approach for cleft palate repair may be a worthwhile investigation.

Alloys↗
PubMedDate not supplied

[Distraction osteogenesis of the cranio-maxillo-facial bones].

Distraction osteogenesis is a surgical technique: its main purpose is to induce a mechanically stimulated bone tissue augmentation. A controlled tension, developed by a slow and gradual separation of the corticotomized/osteotomized bone segments, induces new bone formation and related soft tissue augmentation. In this way, we can observe a more harmonious tissue augmentation, better than with traditional techniques as osteotomies with grafts. This procedure, initially applied in orthopedic field for limb lengthening, is now also applied in the cranio-facial field. The most important features of distraction osteogenesis consist in the simplicity of execution, the lack of donor site morbidity and the simultaneous expansion of bone and related soft tissue. Besides, the technique is still at the beginning and requires further acknowledgements, before being widespread used to treat cranio-facial malformations. Disadvantages in bone distraction are related to the external device and consist in esthetic discomfort during treatment, and cutaneous scars. Recently, to solve these problems an intraoral distraction device was proposed. Distraction osteogenesis has now an expanding role in cranio-facial surgery.

Facial Bones↗
PubMed2002

Intraoperative expansion of skin around large congenital naevi with foley catheter balloons: 11 new cases.

Tissue expansion allows reconstruction of large cutaneous defects with adjacent skin, similar in appearance and type, without using skin grafts or multiple, regional, distant, or microsurgical flaps. Conventional expansion produces a greater increase in surface and length than intraoperative expansion, but it has several disadvantages and should be reserved for closing problematic defects. There is considerable controversy about the relative effects of intraoperative expansion and undermining on the tensions of closing wounds, although immediate expansion is commonly used particularly in head and neck reconstruction. New multiple external devices have recently been described to expand skin externally, but there are few options as internal expanders. We have chosen multiple Foley catheter balloons, because of their availability and low cost, to repair 11 limb defects after excision of large naevi. The wounds are easy to close, primarily, and postoperative results are good. Dark pigmentation scars are the most common possible complications.

Adolescent↗
PubMed1994

Wound closure using a skin stretching device.

The recent development of an indexed tissue advancement system makes it possible to take advantage of the viscoelastic properties of skin to close large wound deficits in one procedure. A case is presented in which serial excision of a previous split-thickness skin graft and tissue expansion to achieve wound coverage were performed in one sitting to close an 8cm defect on the lateral side of the patient's leg without subsequent wound separation or dehiscence.

Child↗
PubMed1996

Closure of the fibula free flap donor site with the Sure-Closure skin-stretching device.

Fibula osseocutaneous free tissue transfer represents state-of-the-art reconstruction of the oromandibular complex following oncologic resection. The width of the fibula skin paddle is usually limited by the ability to achieve primary wound closure. In some cases the donor site requires skin grafting and subsequent surgical procedures to achieve effective closure, or placement of a tissue expander. The recent development of an indexed tissue advancement system (Sure Closure) makes it possible to take advantage of the viscoelastic properties of skin to close large wound deficits in a single procedure. The system secures and brings together wound edges by applying graduated pressure with a metered force approximator. A series of 12 fibula osseocutaneous free flap defects is presented, which have been successfully closed using this simple, convenient, and safe device.

Bone Transplantation↗
PubMed1994

A comparison of two different rapid palatal expansion techniques from the point of root resorption.

The aim of this investigation is to compare Haas and Cast Cap Splint devices from the point of root resorption. The material comprised thirty-eight upper and twelve lower premolar teeth derived from nineteen patients who required RME and subsequent removal of the first premolars as part of their full banded orthodontic treatment. Root resorption and repair areas were observed on the buccal surfaces of premolars. Repair tissue was cellular cementum in both groups. There was no significant difference between these two techniques from the point of root resorption amount.

Adolescent↗
PubMed2000

Islet cell transplantation: the future?

BACKGROUND: Islet of Langerhans' cell transplantation is a promising strategy for the treatment of type-1 diabetes mellitus. Results of this procedure have yet to match those of whole organ pancreas transplantation, but are rapidly improving, as witnessed by increasing rates of insulin independence and graft function (i.e., C-peptide production) after islet transplantation. DISCUSSION: Identification of obstacles to the success of islet transplantation, such as primary nonfunction, immunosuppression-related metabolic workload, or recurrence of autoimmunity, will allow the development of new strategies tailored to overcome them. In particular, novel immunosuppressive protocols, with or without the aim of inducing tolerance, and immunoisolation devices are reaching the stage of clinical applicability. Finally, several strategies, such as utilization of porcine xenogeneic islets or genetically engineered beta-cell lines, or in vitro expansion of cultured beta-cells could theoretically expand indefinitely the pool of islet tissue for transplantation.

Diabetes Mellitus, Type 1↗
PubMed1995

New devices for scalp reduction. Intraoperative and prolonged scalp extension.

BACKGROUND: Scalp reduction for male pattern and other extensive, permanent crown-vertex alopecias has been a beneficial, adjuvant procedure in hair replacement surgery and has been augmented by unsightly and sometimes painful intraoperative and chronic scalp expansion techniques. METHODS: Ten patients underwent scalp reduction for male pattern baldness utilizing intraoperative Sure-Closure, a skin-stretching device. Ten patients had Frechet Extenders placed under the scalp during their scalp reductions with subsequent removal 28 days later followed immediately by second reduction procedures. RESULTS: The skin-stretching device, Sure-Closure, allowed the excision of 20%-30% more alopecic scalp during scalp reduction than what would have been possible with scalp reduction alone. The Frechet Extender when combined with a lazy S excision pattern for scalp reduction procedures generated between 25% and 50% more excision of alopecic scalp than with scalp reduction alone. CONCLUSION: Scalp reduction procedures can be more effectively performed with minimal complications and fewer reductions required per patient using either intraoperative scalp extension with the Sure-Closure device or chronic scalp extension with the Frechet Extender.

Alopecia↗
PubMed2005

The treatment of spine and chest wall deformities with fused ribs by expansion thoracostomy and insertion of vertical expandable prosthetic titanium rib: growth of thoracic spine and improvement of lung volumes.

STUDY DESIGN: Prospective clinical trial of vertical expandable prosthetic titanium rib (VEPTR) in patients with combined spine and chest wall deformity with scoliosis and fused ribs. OBJECTIVE: Report the efficacy and safety of expansion thoracostomy and VEPTR surgery in the treatment of thoracic insufficiency syndrome (TIS) associated with fused ribs. SUMMARY OF BACKGROUND DATA: Traditional attitudes toward early-onset combined chest and spine deformity assume that thoracic deformity is best controlled by treatment directed at spine deformity, often involving early spinal arthrodesis. Campbell and others have heightened awareness of the interrelationship between lung, chest, and spine development during growth and characterized TIS as the inability of the thorax to support normal respiration or lung growth. Expansion thoracostomy and VEPTR insertion was developed to directly control both spine and chest wall deformity during growth, while permitting continued vertebral column and chest growth at an early stage. METHODS: Multidisciplinary evaluation of children with combined spine and chest wall deformity included pediatric pulmonologist, thoracic, and orthopedic surgeon evaluations. One or more opening wedge expansion thoracostomies and placement of VEPTR devices were performed as described by Campbell, with repeated device lengthenings during growth. Parameters measured included Cobb angle, length of thoracic spine, CT-derived lung volumes, and in older children pulmonary function tests. RESULTS: Thirty-one patients with fused ribs and TIS were treated, 4 of whom had undergone prior spinal arthrodesis at other institutions with continued progression of deformity. In 30 patients, the spinal deformity was controlled and growth continued in the thoracic spine during treatment at rates similar to normals. Increased volume of the constricted hemithorax and total lung volumes obtained during expansion thoracostomy were maintained at follow-up. Complications included device migration, infection, and brachial plexus palsy. CONCLUSIONS: Expansion thoracostomy and VEPTR insertion with serial lengthening may be the preferred treatment for young children with chest wall deformity and scoliosis associated with fused ribs but requires multidisciplinary care and attention to details of soft tissue management. When indicated, surgical intervention with VEPTR can be considered early in growth, before deformity is severe, since spinal growth will continue with treatment.

Abnormalities, Multiple↗
PubMed1987

Tissue expanders in reconstructive surgery.

The shortage of skin and soft tissue has been the limiting factor in many reconstructive problems. Tissue expanders (a temporary inflatable device) were recently introduced, to provide the solution. In the first 25 patients of our series of patients age 7 years to 46 years, a total of 30 expanders were used in different parts of the body. The expanders used were made by Cox-Uphoff (CUI) and varied in size from 30 ml to 1000 ml, with an attached remote valve. These expanders were placed subcutaneously, subfascially or submuscularly. Expansion was carried out as an outpatient procedure over a period of 6 weeks. 21 of the 25 patients underwent successful treatment. Failures were due to technical problems, extrusion of expanders, haematoma and infection. Tissue expanders are a new dimension in reconstructive surgery. They cause stretching of skin and soft tissues over a period of time and permit resurfacing of skin defects in difficult situations. Complications may be avoided with experience and further refinements in the construction of the expanders.

Adolescent↗
PubMed2005

Thermal expansion of blood vessels and muscle specimens permeated with DMSO, DP6, and VS55 at cryogenic temperatures.

As part of an ongoing effort to characterize the continuum mechanics during cryopreservation via vitrification (vitreous in Latin means glass), the current study focuses on measuring the thermal expansion of cryoprotective agents in the presence and absence of biological samples of bovine muscle and goat arteries. The cryoprotectants under investigation are 7.05 M DMSO, DP6, and VS55, with permeation time of up to 48 h. This study focuses on the upper part of the cryogenic temperature range, where the cryoprotectant behaves like a liquid in all practical applications. The specific lower boundary of this range is unique to the cryoprotectant composition and to the applied cooling rate. The measurement device used in the current study is a modification of a prototype presented recently, in which modifications are made to accommodate biological samples. Based on thermal strain observations, it is concluded that the presence of tissue samples promotes crystallization (the tissue samples serve as potential nucleation sites). It is shown in this study that the thermal strain of tissue samples permeated with 7.05 M DMSO and DP6 is no greater than the thermal expansion of the same cryoprotectants in the absence of tissue samples, and in some cases it is significantly less. For a given cryoprotectant in comparable thermal conditions, experiments on bovine muscle samples show significantly higher scattered data than experiments on artery samples.

Animals↗
PubMed1996

Intravascular ultrasound for evaluation of coronary arteries.

Intravascular ultrasound (IVUS) has emerged form a research tool to an intrinsic part of modern invasive cardiology. The main reason is the capability to obtain "in vivo" histology. For the first time it is possible to base decisions not only on lumenograms but also on vessel wall assessment. The capabilities of IVUS can be divided in its (a) diagnostic and (b) intervention associated potentials. Diagnostic strength of IVUS is the ability to monitor compensatory coronary artery enlargement as a response to arteriosclerosis, to assess intermediate lesions, to reveal occult left main stem disease, and angiographycally "silent" arteriosclerosis. The intervention associated potentials of IVUS are the ability to allow optimal device selection, i.e. rotablators in calcified lesions or atherectomy devices in large plaque burden. The effects of PTCA on vessel wall morphology can be studied in great detail and the effect on luminal gain can be assessed almost on-line. Several groups showed, that the residual plaque area even after angiographycally successful PTCA lies still in the range of 60%. A significant reduction of this number may influence longterm outcome after PTCA. Minimal luminal areas and residual plaque area after PTCA seem to be an indicator of restenosis, while the presence or absence of dissections seem to be less predictive. Intravascular monitoring of stent expansion led to high-pressure stent deployment with significant increase in post-procedural luminal diameters and finally the ability to withhold anticoagulation in patients with optimal stent deployment. In the future, integrated devices, like balloons on intravascular ultrasound catheters, steerable catheters, integrated flow and pressure transducers, tissue characterization, and 0.018 "intravascular ultrasound guide-wires will further enhance the usefulness of IVUS.

Angioplasty, Balloon, Coronary↗
PubMed1999

Monobloc and facial bipartition distraction with internal devices.

Distraction osteogenesis (DO) permits gradual lengthening of the craniofacial skeleton. With the advent of new internal devices, monobloc (M) and facial bipartition (FB) DO are feasible. The rationale behind M and FB distraction is (1) gradual advancement of the M segment is not associated with a substantial retrofrontal dead space; (2) because 5 to 7 days elapse prior to distraction, the nasofrontal opening, in theory, is allowed to remucosalize; (3) gradual expansion of the soft tissues takes advantage of skin creep, potentially limiting relapse; (4) the procedure appears to be less invasive with decreased blood loss and operative time, enabling its use in infants; (5) overdistraction may eliminate or reduce the frequency of subsequent procedures; and (6) the procedure may be combined with FB and skull vault remodeling to provide excellent results in more complex craniofacial dysostosis problems. Five children underwent M advancement (N = 3) and M with FB (N = 2) at 9 months to 5 years of age to correct functional abnormalities such as corneal exposure, increased intracranial pressure, and apnea, as well as severe craniofacial disfigurement. Each patient underwent from 22 to 30 mm of distraction with the Modular Internal Distraction (MID) system, developed by the first author (SRC). There was one infection late in the series along the DO cable track. There were no cases of epidural abscess. In conclusion, MDO, with and without FB, appears to be a safe and effective technique for transcranial frontofacial advancement. The morbidity of the procedure appears to be less than that of conventional M advancement.

Acrocephalosyndactylia↗
PubMed2005

Gunshot wounds: reconstruction of the lower face by osteogenic distraction.

BACKGROUND: Although osteogenic distraction is a well-established technique, the distraction device still needs to be improved, miniaturized, and made lighter, more flexible, and more adaptable for mandibular reconstruction in adults with gunshot wounds. The authors successively used unidirectional and bidirectional devices, followed by a bone transporter with a horseshoe-shaped trammel. The trammel system was then replaced by an endless screw, and finally by a customized endless screw. METHODS: Eleven adult patients with gunshot injuries underwent mandibular reconstruction using osteogenic distraction with an external device. RESULTS: An average bone gain of 79 mm was achieved. No infectious complications were observed. The authors encountered equipment problems during the study, requiring a change of material. The mean duration of mandibular distraction was 3.5 months. CONCLUSIONS: Distraction of bone fragments facilitates the simultaneous expansion of soft tissues, avoiding free or pedicled myocutaneous flaps, for soft-tissue reconstruction. The alveolar ridge with the attached gum is also recreated by distraction, allowing dental reconstruction by osseointegrated implants.

Adult↗
PubMed1996

External tissue stretching for closing skin defects in 22 patients.

In this prospective study, we treated 12 women and 10 men with a newly developed skin-stretching system. The stretching device was used for the closure of 9 fasciotomies and for preoperative skin extension before excision of 6 tattooes, 7 splitskin transplants, 4 giant naevi, and 3 scars. The stretching device was placed under the skin, using local anesthesia. The patient stretched the skin. The mean stretching time was 4 (2-11) days. 20 patients completed the expansion successfully, with no pain or only slight discomfort. In 2 cases, we observed minor complications during the expansion. The external skin-stretching system can be used to obtain primary closure of defects where splitskin transplants otherwise would be necessary. The method can be applied in out-patients, using local anesthesia.

Adolescent↗
PubMed1995

Intravascular ultrasound: a guide for management of complications during intervention?

Within a few years, intravascular ultrasound (IVUS) has emerged from a research tool into an intrinsic part of modern invasive cardiology, mainly because histology can be obtained 'in-vivo'. For the first time in invasive cardiology it is possible to base decisions not only on lumenograms but also on vessel wall assessment. IVUS can be used as both a diagnostic tool and for intervention purposes. Its diagnostic strength lies in its ability to monitor compensatory coronary artery enlargement as a response to arteriosclerosis, to reveal occult left main stem disease, and angiographically 'silent' arteriosclerosis. As regards intervention, IVUS aids in optimal device selection, i.e. whether to use rotablators in calcified lesions or atherectomy devices in large plaques. The effects of PTCA on vessel wall morphology can be studied in great detail and the effect on luminal gain assessed almost on-line. Several groups have shown that the residual plaque area, even after angiographically successful PTCA, is about 60%. A significant reduction in this percentage may influence long-term outcome after PTCA. Luminal areas that are minimal after PTCA seem to indicate restenosis, while morphological appearance on its own seems to be less predictive. One answer to the shortcomings of standard PTCA are coronary artery stents. Intravascular monitoring of stent expansion led to the deployment of high-pressure stents with a significant increase in post-procedural luminal diameters, and finally the ability to withhold anticoagulation in patients with optimal stent deployment. Furthermore, integrated devices, such as balloons on IVUS catheters, steerable catheters, integrated flow measurements, pressure transducers, and, hopefully, tissue characterization, will further enhance the usefulness of IVUS.

Angioplasty, Balloon, Coronary↗
PubMed1996

Association of latissimus dorsi muscle expansion with electrostimulation before cardiomyoplasty.

BACKGROUND: The principle of cardiomyoplasty is chronic electrostimulation of the latissimus dorsi muscle (LDM) flap wrapped around the heart to obtain a phasic activity that can be integrated to ventricular kinetics. In clinical cardiomyoplasty procedures, a complete wrap of both ventricles by the LDM cannot always be obtained in cases of extremely dilated hearts. This is due to the limited LDM length available for wrapping. In most of these cases, benefits of cardiomyoplasty are very limited. We have investigated the feasibility of progressive LDM expansion associated with electrostimulation. The aim was to increase the muscle area before cardiomyoplasty, while preserving the electrophysiologic characteristics of muscle fibers. METHODS: In 5 goats, a silicone LDM expander with two incorporated muscular pacing electrodes was inserted deep into the LDM through a paravertebral incision along the posterior edge of the muscle. The pacing leads were connected to a myostimulator implanted in a subcutaneous pocket. The expander was progressively inflated over 8 weeks, up to 500 mL. Simultaneously the LDM was electrostimulated. RESULTS: At 2 months planimetric studies demonstrated an increase of the LDM surface from 175 +/- 12 to 229 +/- 17 cm2 (+31% +/- 4%; p < 0.05). The expanded LDM showed preserved electrophysiologic characteristics. The analysis of biopsy samples revealed histologic integrity of muscle fibers and preservation of their mean diameter. CONCLUSIONS: Potential benefits of this procedure are (1) increase of muscle surface, (2) training of muscular fibers and preservation of muscular tone, and (3) division of the distal vascular supply at implantation, which may potentiate vascularization from the LDM main pedicle. An LDM expansion could be considered before cardiomyoplasty in cases of significant heart dilatation. This device was successfully implanted in 2 patients, 2 months before cardiomyoplasty. Cardiomyoplasties were performed without difficulty, and a complete biventricular wrap was obtained in both patients in spite of massive cardiomegaly.

Animals↗