Eighty-four consecutive breast reconstructions using a textured silicone tissue expander.

Breast reconstruction utilizing smooth-surface silicone tissue expanders is associated with certain problems. Significant capsular contracture may develop around the expander with subsequent expander displacement necessitating repositioning or capsulectomy at the time of expander removal. Infection, pain on expansion, chest-wall compression, and complications related to the remote fill valve also have been reported. A textured-surface silicone expander with an integrated fill valve was developed to address these issues. Eighty-four consecutive breast reconstructions were performed by a single surgeon using textured expanders in 55 patients. Intraexpander pressures were measured during expansion for a group of these patients, and both initial and postinflation pressure readings were quite low (average initial pressure 2.88 mmHg; average postinflation pressure 12.87 mmHg). Eighty-one of the reconstructions have been completed without any expander losses and with minimal complications. Tissue expander volume averaged 580 cc, and the expansion duration averaged 5.6 months. Various types and configurations of permanent implants were used to complete the reconstructions. Eighty-four percent of our patients' completed reconstructions (including nippleareola reconstruction and opposite breast alteration, when necessary) were accomplished with just two procedures. Seventeen long-term adjustable textured-surface expander/implants with anatomic breast shape are still in place, all after only one operation. The inframmary fold has generally been established passively by the expansion process alone. Textured-surface silicone expanders have stayed where positioned, have expanded easily with minimal patient pain, and have created a noncontractile soft-tissue cover for the final implant. The textured expander with an integrated fill valve has simplified breast reconstruction by helping to limit the problems encountered with smooth silicone expanders. The resulting reconstructions have remained soft with a very acceptable aesthetic appearance. The patient office and hospital charts and photographs of this consecutive series were notarized and submitted to the Editor of this Journal, whose biostatistician randomly selected the cases illustrated.     

Use of external reservoirs in tissue expansion

The use of tissue expanders having external reservoirs is presented. Twenty-four patients had 36 tissue expanders placed in the scalp, face, neck, upper limbs, chest, and lower limbs. All patients, apart from one, were taken to completion. This patient had erosion of the skin over expander and was only partially completed after removal of the expander. Apart from one instance of deflation at the end of the expansion where the skin could still be used, there were no other complications, in particular, no infections. The advantages of this technique are reduced operating time, ease of injection into the reservoir, lack of pain for the patient, early detection of reservoir or filling tube junction leakage, and lack of complications associated with the reservoir. This procedure is not recommended on at least theoretical grounds for breast expansion, where a permanent implant is to be inserted.     

Breast reconstruction using tissue expanders and implants in Hodgkin's patients with prior mantle irradiation.

Women treated for Hodgkin's disease with mantle irradiation have an increased risk for developing breast cancer. Typically, breast malignancy in Hodgkin's patients presents bilaterally in a younger age group. Skin flap ischemia, poor skin expansion, implant extrusion, capsular contracture, and poor cosmesis are common sequelae of tissue expander/implant breast reconstruction after breast irradiation for failed breast conservation therapy. This has led most surgeons to favor autologous tissue reconstruction in this setting. This study was performed to determine the efficacy of tissue expander/implant breast reconstruction in breast cancer patients who have been treated with prior mantle irradiation for Hodgkin's disease. A retrospective analysis of all breast cancer patients with a history of Hodgkin's disease and mantle irradiation treated with mastectomy and tissue expander/implant reconstruction between 1992 and 1999 was performed. There were seven patients, with a mean age of 35 years (range, 28 to 42 years). The average interval between mantle irradiation and breast cancer diagnosis was 16 years (range, 12 to 23 years). All patients underwent two-stage reconstruction. Textured surface tissue expanders were placed in a complete submuscular position at the time of mastectomy. Expansion was initiated 2 weeks after insertion and continued on a weekly basis until completion. Expanders were replaced with textured surface saline-filled implants as a second stage. Patients were evaluated for skin flap ischemia, infection, quality of skin expansion, implant extrusion, capsular contracture, rippling, symmetry, and final aesthetic outcome. Breast cancer was bilateral in five patients and unilateral in two. Two patients did not undergo simultaneous bilateral breast reconstruction because of metachronous cancer development. One of the patients had an initial transverse rectus abdominis muscle flap breast reconstruction, followed by a tissue expander/implant reconstruction of the opposite breast. The average follow-up was 3 years. Complications were limited to one case of cellulitis after implant placement that resolved with intravenous antibiotics. There were no cases of skin flap ischemia, poor skin expansion, or implant extrusion. Overall patient satisfaction was high and revisions were not requested or required. Symmetry was best achieved with bilateral implants. This study demonstrates the efficacy of tissue expander/implant breast reconstruction in patients treated with prior mantle irradiation. In this series, tissue expansion was reliable with low morbidity. Second-stage placement of permanent implants yielded good aesthetic results without significant capsular contracture. Mantle irradiation did not appear to compromise the prosthetic breast reconstruction. Tissue expander/implant breast reconstruction should remain a viable option in this category of irradiated patients.     

The premature removal of tissue expanders in breast reconstruction.

The role of tissue expanders in breast reconstruction is well established. Little information exists, however, regarding the incidence and etiology of premature removal of the tissue expander before planned exchange to a permanent breast implant. The purpose of this study was to review our 10-year experience with tissue expander breast reconstruction and identify factors relating to the premature removal of the tissue expander. This study is a retrospective review of 770 consecutive patients who underwent breast reconstruction with tissue expanders over the past 10 years. Breast reconstruction was immediate in 90 percent of patients. Patients were expanded weekly, and adjuvant chemotherapy was begun during the expansion process when required. Factors potentially affecting premature expander removal (chemotherapy, diabetes, obesity, radiation therapy, and smoking) were evaluated. Fourteen patients (1.8 percent) with a mean age of 47 years (range, 38 to 62 years) required premature removal of their tissue expander. Expanders were removed a mean of 3.2 months (0.1 to 8 months) after insertion. Causes for premature removal of the tissue expander included infection (7 patients), exposure (2), skin necrosis (2), patient dissatisfaction (2), and persistent breast cancer (1). Positive wound cultures were obtained in four of the seven infected patients (57 percent), requiring expander removal for infection. Tissue expanders were removed in 11 patients for complications directly related to the expander. Among these, six (55 percent) were receiving adjuvant chemotherapy, and one was a smoker. Diabetes, obesity, other concomitant medical illnesses, and prior mantle irradiation were not associated with expander removal. Premature removal of the tissue expander was required in only 1.8 percent of the patients in this series. Infection was the most common complication necessitating an unplanned surgical procedure to remove the expander. This study demonstrates that the use of tissue expanders in breast reconstruction is reliable, with the vast majority of patients completing the expansion process.     

Chest-wall deformity after tissue expansion for breast reconstruction

A prospective longitudinal study of chest-wall deformity after tissue expansion for breast reconstruction was performed in 19 women. CT imaging was a sensitive method for detecting occult deformity. Using a semiquantitative scale for measuring deformity, all patients and 94 percent of expanders had some thoracic abnormality after tissue expansion. Rib and chest-wall contour changes were observed under 81 and 68 percent of the expanders, respectively. Routine chest roentgenograms were not a sensitive method for evaluating these deformities. The magnitude of deformity after unilateral expansion was not significantly different from that after bilateral expansion. Linear regression analysis indicated that early periprosthetic capsular contracture was negatively correlated with chest wall deformity. Only one patient experienced a clinically noticeable complication from chest compression--transient postexpansion exertional dyspnea. After removing the expanders and placing permanent implants along with capsulotomy, the mean deformity index decreased by 57 percent after 10.5 months median follow-up, which was highly significant (p less than 0.001). Our findings suggest that chest-wall deformity is a common occurrence after tissue expansion in patients undergoing breast reconstruction and is usually of minor clinical significance.     

Enhancement of tissue expansion by anticontractile agents

To evaluate the effect of anticontractile agents on the rate of tissue expansion, guinea pig back skin was expanded while being treated with various anticontractile agents. Expansion was carried out using standard percutaneous inflatable skin expanders modified by the addition of a catheter to deliver the anticontractile agents papaverine or cytochalasin D. Expansion proceeded for 25 days with one or other of the substances being infused through the catheter; saline was used in a separate control group. Measurements of the rate and extent of expansion showed that there was a statistically significant increase in these parameters for the experimental groups as compared with saline controls. Histologic examination of the expanded tissue suggests that the cellular basis for this phenomenon may involve the relaxation or inactivation of contractile fibroblasts in the fibrous capsule surrounding the expander.     

Continuous versus intraoperative expansion in the pig model.

Continuous tissue expansion utilizing a continuous infusion device that maintains a constant expander pressure was previously demonstrated to be feasible and successful in obtaining rapid tissue expansion in a canine model. Intraoperative tissue expansion has been described and has gained some clinical acceptance as a method to gain rapid expansion. We compared the efficacy of continuous tissue expansion versus intraoperative tissue expansion in a piglet model. After completing a pilot study, continuous tissue expansion was performed in six pigs (14.5 to 20 kg) on one flank over a 3-day period utilizing an improved prototype device; at the termination of continuous tissue expansion, intraoperative tissue expansion was performed on the opposite flank. There were no complications or continuous tissue expansion device malfunctions. Intraoperative tissue expansion gave a true gain in area of 7.4 percent, while continuous tissue expansion produced a 22 percent gain (p < 0.02). When the effects of both recruitment and expansion were added, continuous tissue expansion gave a dividend of 286 percent versus 192 percent for intraoperative tissue expansion (p < 0.01). Biomechanically, intraoperative tissue expansion skin showed few differences from unexpanded skin, while continuous tissue expansion skin showed a significant increase in stress relaxation (47.78 versus 38.74) and decrease in breaking strength. Histologic analysis revealed some epidermal hyperplasia and inflammation surrounding the continuous tissue expansion expander and some vascular congestion over the intraoperative tissue expansion expander. We conclude that continuous tissue expansion is superior to intraoperative tissue expansion and that the prototype device may be useful clinically.     

Immediate breast reconstruction with tissue expansion

Between October of 1983 and June of 1985, 31 patients underwent primary breast reconstruction with tissue expansion. Tissue expansion was utilized for breast reconstruction when the remaining muscle and skin following modified radical mastectomy was insufficient to accommodate a prosthesis that matched in size and shape the opposite breast. All expanders were placed beneath an investing muscular pocket created by elevating the pectoralis major and serratus anterior. Postoperative expansion began within 1 week, and the breast was expanded to double the volume of the opposite breast. Twenty-two patients have completed their reconstruction with a mean follow-up in 7 months. There were nine complications, including five deflations and four infections. All patients have remained Baker I or Baker II. Creating ptosis to match the breast was accomplished by placing the expander below the rectus fascia and superiorly advancing this expanded tissue at the time of prosthesis placement. Primary breast reconstruction with tissue expansion following modified radical mastectomy is safe, simple, and produces a breast with excellent shape, size, texture, and patient satisfaction.     

Patient-activated controlled expansion for breast reconstruction with controlled carbon dioxide inflation: a feasibility study

This feasibility study represents the first report of a new carbon dioxide-based tissue expander designed to allow gradual controlled expansion and to eliminate the need for percutaneous injections. Seven patients underwent implantation with a total of 10 (three bilateral) tissue expanders. After intraoperative filling by the surgeon and wound healing, small doses of carbon dioxide were administered on a daily basis by the patient by means of a hand-held dosage controller leading to gradual, incremental expansion. Rapid expansion during the active dosing phase and flexibility to meet individual patient needs during expansion were demonstrated with all subjects. These patients achieved full expansion in an average of 15 days. All seven patients were able to use the device safely and with ease at home, leading to successful tissue expansion and permanent breast reconstruction. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.     

Long-term effects of tissue expansion on cranial and skeletal bone development in neonatal miniature swine: clinical findings and histomorphometric correlates

Progressive tissue expansion induces significant gross, histologic, and bony changes in skulls and long bones of neonatal miniature swine. These bony changes consist of erosion underlying tissue expanders, with bony lipping and bone deposition at the periphery of the expander. Cranial suture lines underneath expanders appear effaced and convoluted. Serial CT scans reveal decreased bone thickness and volume (p less than 0.02) but identical bone density (p = 0.60) beneath expanders. Increased bone volume and thickness occur at the periphery of expanders (p less than 0.02). Bone density (CT number) is unaffected by tissue expansion in both cranial and long bones. These findings have histomorphometric correlates: Osteoclastic bone resorption occurs underneath expanders with periosteal reaction at the periphery of expanders. Cranial sutures are similarly affected, but no cranial synostosis results. No changes to the inner table of the skull or stigmata of increased intracranial pressure were observed either in CT scans or in behavioral changes in long-term animals. The pathophysiology of bony changes is a remodeling effect, not one of simple pressure deformation. Increased bone resorption and complete inhibition of bone formation occur until the pressure is removed. Cranial bone is significantly more affected than long bone. After removal of the expanders, reparative bone remodeling begins within 5 days and nearly complete healing of the cranial defects occurs within 2 months (p less than 0.02). No plagiocephaly results despite early coronal suture changes. On the basis of this study, we conclude that tissue expansion causes significant but reversible effects, readily monitored by high-resolution CT scans, on neonatal and infant cranial and long bones.     

Effect of radiation on skin expansion and skin flap viability in pigs

The aim of the present study was to investigate the effect of radiation treatment both on skin tissue expansion with the chronic inflation of subcutaneous expanders and on skin flap viability in surgically delayed and expanded skin in the pig. One flank in each of six pigs (initially weighing 17 +/- 1.8 kg) was randomly assigned for radiation treatment, and the contralateral flank served as a nonirradiated control. Three mirror-image, 8 x 10 cm, rectangular templates were marked on each flank; these templates were randomly assigned to the construction of a delayed skin flap (group A), a skin flap raised on expanded skin (group B), or a skin flap raised on expanded skin with a capsulectomy before flap surgery (group C). Radiation treatment was performed using sequential radiation with three fractions per week (810 cGy/fraction) for 2 weeks, with a total dose of 4,860 cGy. Twelve weeks after radiation treatment, skin expanders (8 x 10 cm) were installed subcutaneously in the locations assigned for skin expansion. Skin expansion by the inflation of subcutaneous skin expanders with saline twice weekly was started 8 weeks later and lasted for 3 weeks. Two weeks after surgical delay and the last skin expansion, 8 x 20 cm skin flaps were raised on the locations assigned for delayed skin flaps, expanded skin flaps, and expanded skin flaps with a capsulectomy. Skin flap viability was assessed 24 hours later using a fluorescein dye-staining technique. Skin expansion by the inflation of subcutaneous expanders with saline was slower (p < 0.05) in the radiated skin (39 +/- 6 ml/filling) than in the nonirradiated control skin (51 +/- 6 ml/filling). Radiation reduced the overall area of expanded skin by 23 percent (p < 0.05) compared with the control. Radiation treatment also reduced skin viability by 36 percent (p < 0.05) in the delayed skin flaps, 27 percent (p = 0.10) in the expanded skin flaps, and 36 percent (p < 0.05) in the expanded skin flaps with a capsulectomy when compared with their contralateral, nonirradiated controls. There were no significant differences in skin viability among these three types of skin flaps within the radiated and nonirradiated groups. Taken together, these observations indicate that radiation treatment reduced the effectiveness of the surgical delay procedure, the amount of subcutaneous skin expansion (by an increase in skin area), and skin flap viability. However, a capsulectomy alone did not affect the viability of skin flaps raised on expanded skin.     

Irradiation after immediate tissue expander/implant breast reconstruction: outcomes, complications, aesthetic results, and satisfaction among 156 patients

Chest wall irradiation is becoming increasingly common for mastectomy patients who have opted for immediate breast reconstruction with tissue expanders and implants. The optimal approach for such patients has not yet been defined. This study assesses the outcomes of a reconstruction protocol for patients who require irradiation after tissue expander/implant reconstruction. The charts of all patients who underwent immediate tissue expander/implant reconstruction at Memorial Sloan-Kettering Cancer Center between January of 1995 and June of 2001 and who had not previously undergone irradiation were retrospectively reviewed. A subgroup of patients who required chest wall irradiation after mastectomy and reconstruction was identified. Those patients were treated according to the following treatment algorithm: (1) reconstruction with tissue expander placement at the time of mastectomy , (2) tissue expansion during postoperative chemotherapy, (3) exchange of the tissue expander for a permanent implant approximately 4 weeks after the completion of chemotherapy, and (4) chest wall irradiation beginning 4 weeks after the exchange. All irradiated patients with at least 1 year of follow-up monitoring after the completion of radiotherapy were evaluated with respect to aesthetic outcomes, capsular contracture, and patient satisfaction. A control group of nonirradiated patients was randomly selected from the cohort of patients treated during the study period. During the 5-year study period, a total of 687 patients underwent immediate reconstruction with tissue expanders. Eighty-one patients underwent postoperative irradiation after placement of the final implant. A total of 68 patients who received postoperative chest wall irradiation underwent at least 1 year of follow-up monitoring after the completion of radiotherapy, with a mean follow-up period of 34 months. Seventy-five nonirradiated patients were evaluated as a control group. Overall, 68 percent of the irradiated patients developed capsular contracture, compared with 40 percent in the nonirradiated group (p = 0.025). Eighty percent of the irradiated patients demonstrated acceptable (good to excellent) aesthetic results, compared with 88 percent in the nonirradiated group (p = not significant). Sixty-seven percent of the irradiated patients were satisfied with their reconstructions, compared with 88 percent of the nonirradiated patients (p = 0.004). Seventy-two percent of the irradiated patients stated that they would choose the same form of reconstruction again, compared with 85 percent of the nonirradiated patients. The results of this study suggest that tissue expander/implant reconstruction is an acceptable surgical option even when followed by postoperative radiotherapy and should be considered in the reconstruction algorithm for all patients, particularly those who may not be candidates for autogenous reconstruction.     

Accelerated tissue expansion with the "overfilling" technique

Temporary overexpansion of the tissues at each filling session increased the actual inflation volume by about 59 percent. This shortened the process of tissue expansion considerably. "Overexpansion" means that the pressure in the expander is increased to a point where the dermal capillary flow is zero or the patient experiences so much discomfort that inflation cannot be carried out any further. The pressure in the expander is thereafter gradually decreased by taking out saline until both the capillary refill and all other clinical criteria are sufficient for safe dermal circulation. Comparison of the expander volume at the final pressure to the initial filling volume at the same pressure before the "overfilling" confirmed an average gain of about 59 percent in 14 patients.     

The role of tissue expanders in an anophthalmic animal model

A study of orbital bony expansion using a custom tissue expander was performed in the anophthalmic cat model. Twelve 6-week-old kittens underwent right unilateral enucleations. Six kittens had immediate insertion of a tissue expander into the orbit. The remaining six served as controls. Every 2 weeks 0.5 cc saline was injected into the expander to a maximum of 5 cc. External horizontal and vertical orbital dimensions were obtained by palpation technique weekly. All animals had preoperative and study conclusion head CT scans with three-dimensional reconstructions performed. Dry skull preparations were done at the study conclusion at 24 weeks. Results demonstrated that tissue expanders were successful in maintaining normal orbital growth and size relative to the contralateral control orbit. The animals with enucleation only had an average difference in vertical and horizontal orbital measurements of -27 and -13 percent when compared with the contralateral normal orbit. In contrast, the enucleation and tissue-expansion animals had vertical and horizontal measurements of +4 and +2 percent (p less than 0.05) when compared with the contralateral orbit. Head CT scans with three-dimensional reconstructions demonstrated normal orbital geometry and volume for the animals with tissue expanders, whereas animals with enucleation only had small hypoplastic orbits. In conclusion, orbital tissue expanders offer a promising new technique in the treatment of anophthalmos.     

The beginning of a new era in tissue expansion: self-filling osmotic tissue expander--four-year clinical experience

The osmotic tissue expander is a new device made of a hydrogel expanding skin that does not require external fillings. Once implanted, it absorbs body fluids, which leads to a gradual swelling of the device. The swelling phase is completed in 6 to 8 weeks and results in skin gain. Different shapes and sizes are available, and the devices can be used in almost every area of the body. Over a 4-year period, the osmotic tissue expander was used in 58 patients in different areas of the body. A round osmotic tissue expander was mainly used in breast reconstruction, and a rectangular expander was used for defect coverage after excision (i.e., of scars and tumors). The mean age of the patients was 49.34 years (range, 4 to 76 years). During the expansion phase, the patients noted only a little discomfort and pain for the first few days. Without a silicone membrane in the first-generation expander, the rate of successful explantation and good final result was 81.5 percent. In a few cases, rapid swelling of the device led to the introduction of a silicone membrane that encloses the expander and leads to a slower, more gradual, and consistent swelling. After introduction of the silicone envelope, the success rate improved to 91 percent. The expander is now used with a silicone membrane in every case. The osmotic tissue expander has many advantages compared with the conventional expander: there is no need for painful external fillings and the risk of external infections is avoided. The expander is 10 percent of its final volume and only requires a short incision and a small pocket. An operation can easily be performed under local anesthesia, with minimal tissue mobilization in older children and compliant patients.     

Three-dimensional assessment of transverse dentoskeletal mandibular dimensions after utilizing two designs of fixed mandibular expansion appliance: A prospective clinical investigation

The aim of this clinical study was to evaluate and compare the dentoskeletal transverse mandibular arch dimensions following the use of two designs of fixed mandibular expanders using cone beam computed tomography (CBCT). Twenty orthodontic patients, 12 females and 8 males, with mean age of 13.4 ± 0.5 years were selected and randomly divided into two equivalent groups; group A consisted of 10 patients (4 boys, 6 girls) who were treated with modified Williams expander and group B consisted of 10 patients (4 boys, 6 girls) who were treated with a two-arm fixed expander. Consistent expansion instructions were given to all patients according to a standardized slow protocol of one quarter turn twice/week for both expanders. Routine orthodontic records as well as mandibular CBCTs were obtained before (T1) and immediately after expansion (T2) to estimate changes in dentoskeletal mandibular transverse dimensions. The data was statistically analyzed and the significance level was set at p ≤ 0.05. Mandibular intercanine, inter-premolar, intermolar widths; and arch perimeter were significantly increased (p ≤ 0.05) following expansion with both fixed expanders. However, the changes in inter-premolar width, intercanine width, and arch perimeter were significantly augmented in two-arm fixed expander group than modified Williams’s group. In contrast, their effects on the skeletal mandibular body width were non-significant (p > 0.05). Both expanders yielded significant and equivalent dentoalveolar effects that were more evident with two-arm fixed expander than the William one. Both fixed designs enhanced mandibular transverse dental dimensions; however, they were unsuccessful to create any considerable skeletal effects.     

Intraoperative tissue expansion in rhytidectomy revisited

Intraoperative tissue expansion is an adjunct that has been used during rhytidectomy to rejuvenate the face and neck. This technique has been thought to allow for additional skin resection and, thus, increased skin tightening during rhytidectomy. The stretch of the skin by expansion should allow for additional skin resection before closure. Also, when the force of the underlying expander is removed, the expanded skin would recoil and the advancement of the flap should become tighter, with improved results. The technique achieved some popularity a few years ago but has received little recent attention. In this study, the authors attempted to compare face-lift results of adjunctive intraoperative tissue expansion during rhytidectomy with similar techniques without intraoperative expansion. The results of 50 female patients who underwent rhytidectomy for midface rejuvenation by a single operating surgeon composed the study group. Twenty-five of the patients had undergone rhytidectomy that addressed the cheek, chin, and neck areas without expansion (nonexpanded rhytidectomy group). The other 25 patients (expanded rhytidectomy group) had adjunctive intraoperative tissue expansion performed with the rhytidectomy. A tissue expander was temporarily placed beneath the rhytidectomy flaps on each side and expanded in a standard manner before final skin resection and closure. Frontal and lateral photographs were evaluated by 54 examiners. Preoperative and postoperative photographs of the 50 patients were viewed side-by-side by the examiners. The patients were presented in blind fashion and random order. The examiners graded the results of each patient on a scale of improvement from 1 to 10, with 10 being the maximum level of improvement. The scores were recorded and statistically evaluated by using the two-sample test. Evaluation of the examiners' scores showed that the mean rating given to patients in the expanded rhytidectomy group was 5.07 (SD = 1.12). The mean rating for the nonexpanded rhytidectomy group was 5.27 (SD = 1.57). When the two groups were compared using the two-sample test, the difference between the two was not statistically significant (p = 0.6127). Intraoperative tissue expansion as an adjunct to rhytidectomy did not result in improved facial rejuvenation in this patient series. The authors' impression is that the benefits of tissue expansion do not justify the added expense, time, and risks associated with using tissue expansion during rhytidectomy.     

Accelerating tissue expansion by application of topical papaverine cream

The rate of tissue expansion can be accelerated by papaverine through a special delivery system, according to an early report. Because the delivery system was complex and inconvenient, another means of administrating papaverine was tested to observe the rate of tissue expansion. In this study, 24 miniature pigs were divided equally into three groups. Four 150-ml silicone expanders were implanted into each pig in groups A and C. Four modified rectangular silicone expanders were also implanted into each animal in group B. During the expansion process, 1 g of 2% hydrochloride papaverine cream was applied topically onto the surface of each pig's expanding skin in group A two times daily, and hydrochloride papaverine solution was injected into the outer shell of each modified expander in group B weekly. Group C acted as the control group. The mean sum of the first four times of saline water volume that was injected into the expanders was 142.42 +/- 5.6 ml in group A, 128.72+/-4.8 ml in group B, and 106.38+/-3.28 in group C. There were statistical differences among the three groups. The mean sum of volume saline water that was injected into hind expanders was 137.51 +/- 5.1 ml in group A, 120.35 +/- 3.6 ml in group B, and 102.63 +/- 4.76 ml in group C, and there was a statistical difference among the three groups as well. There was no statistically significant difference in the thickness of fibrous capsules among the three groups. This study shows that the rate of tissue expansion can be accelerated by topical application of papaverine cream, and the rate is better than the rate of tissue expansion induced by the special drug delivery system.     

Treatment of burn alopecia with tissue expanders in children

During the past 18 months, 60 tissue expanders were utilized in the reconstruction of 42 children with burn alopecia of the scalp not amenable to a single excision and primary closure at the Shriners Burns Institute in Galveston, Texas. The children were grouped according to the degree of alopecia. All patients with defects of 15 percent or less of the total hair-bearing scalp were able to obtain complete closure of their defects with two operations, i.e., one to place the expander and the second to remove the expander and advance the flaps. Some patients with defects up to 40 percent were closed with serial expansion. Patients with even larger defects had a significant reduction in the percentage of alopecia and benefited from re-creation of anterior hairlines. We have encountered a postoperative complication rate of 10 percent. When compared to previous methods of treating burn alopecia, tissue expansion allows a more rapid closure, fewer operations and coincident anesthetics, and decreased total length of hospitalization.     

Quantitative analysis of lidocaine hydrochloride delivery by diffusion across tissue expander membranes.

Permeability of Silastic tissue expander shells to lidocaine was studied to investigate the feasibility of intraluminal lidocaine injection for pain relief during soft-tissue expansion. Both intact expanders and an apparatus using isolated Silastic membrane segments were used to partition solutions of various lidocaine concentrations, and the rate of diffusion was quantitatively measured using a fluorescence polarization immunoassay. Lidocaine flux was found to follow Fick's law of passive diffusion with respect to time, surface area, and concentration gradient for the first 9 hours, with a permeability coefficient of 10.3 +/- 2.6 micrograms (h.cm2.percent)-1 (mean +/- SD) and diffusion coefficient of 7.5 x 10(-7) cm2/min for an average membrane thickness of 473 +/- 23 microns. After 9 hours, the lidocaine flux decreased exponentially, although the concentration gradient across the membrane remained essentially the same order of magnitude. Plasma proteins in the outer bathing solution and methylparaben used as a preservative in the standard lidocaine formulation had no influence on the change in transport flux with time. At the end of the linear portion of the diffusion curve, less than 2 percent of the total intraluminal lidocaine had crossed the membrane. Potential toxicity in the event of implant rupture limits the maximum total lidocaine dose to approximately 500 mg within an expander at any one time. Within these limits, the capacity for lidocaine delivery of 500 mg lidocaine by a 640-cc tissue expander would be only 6 mg during the first 9 hours after administration.(ABSTRACT TRUNCATED AT 250 WORDS)