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PubMed1994

Changing trends in postmastectomy breast reconstruction: a 13-year experience.

Over the past two decades, significant advances have been made in the treatment of breast cancer and reconstruction following mastectomy. This analysis represents a 13-year review (1979-1991) of 455 postmastectomy reconstructions involving 381 patients (age range 25 to 76 years, mean 51 years). Follow-up was 6 months to 13 years (mean 5 years). Timing of the reconstruction, reconstructive techniques used, incidence of complications, and final results were determined. Reconstructions were divided into three chronologic study groups: group I, 1979-1983; group II, 1984-1987; and group III, 1988-1991. A significant increase in the use of autogenous reconstruction was identified: 13 percent in group I to 37 percent in group III (p < 0.0002). Complication rates were not significantly different among the three groups (p > 0.02). Significant decreases in the use of implants alone and the latissimus dorsi flap with implant were identified, while tissue expansion and TRAM flap use increased significantly (p < 0.002). Also, a significant increase in immediate reconstruction from 6 percent in group I to 28 percent in group III occurred (p < 0.0002). There was no significant difference in complication rates between immediate and delayed reconstruction in any study group. Operative time averaged 2 hours less for nonautogenous techniques; however, autogenous reconstruction required significantly fewer operative revisions. The identified trends toward immediate reconstruction and use of autogenous tissue have been accomplished without an increase in complications. Despite a decrease in overall implant use, the textured silicone saline-filled expander/implant remains the most frequently used device for breast reconstruction, providing a safe and predictable method to accomplish both immediate and delayed postmastectomy reconstruction.

Adult↗
PubMed2001

Tension decrease during skin stretching in undermined versus not undermined skin: an experimental study in piglets.

In a controlled study using 15 piglets, the efficacy of skin stretching using a skin stretching device was tested by quantifying the tension decrease during skin stretching in undermined and not undermined wounds. The viability of the skin margins was examined in both situations. Thirty standardized wounds was created: around 15 wounds on one flank, the surrounding skin was undermined; whereas around the 15 wounds on the opposite flank, the surrounding skin was not undermined. The force required to close the 9 x 9 cm defect was measured at the beginning, after undermining, and after 30 minutes of skin stretching. Also examined was the wound healing after 1 day and 1 week. A tension decrease of 3.02 N (13.6 percent reduction of the total force that is required to close the wound at the beginning) was seen due to undermining the surrounding skin. Skin stretching for 30 minutes without undermining the skin showed a tension decrease of 6.10 N (26.5 percent). Therefore, the tension decrease due to skin stretching was twice as high in comparison with undermining the skin margins alone. This has been statistically proven to be significant (-d (difference) = 3.08, 95 percent confidence interval = 2.16; 4.00, p < 0.001). When the undermined skin of the wound was stretched for 30 minutes, we measured a total tension decrease of 7.60 N (34.1 percent). There was a statistically significant but small difference in total tension decrease as a result of undermining combined with skin stretching in comparison with skin stretching without undermining (-d = 1.51, 95 percent confidence interval = 0.77; 2.23, p < 0.001). Undermining the surrounding skin involved cutting musculocutaneous perforating vessels. Looking at the viability of the skin, seven wounds, all found in the undermined group, showed skin necrosis after 1 week. Excessive seroma formation was seen in all wounds around which the skin was undermined. In the not undermined wounds, there were no problems in wound healing. In conclusion, skin stretching for only 30 minutes using a skin stretching device significantly reduces wound closing tension. The additional advantage of skin stretching over that of undermining alone is clearly shown. Undermining the wound margins before skin stretching gives a small additional tension decrease but has well-known complications, such as skin-edge necrosis and seroma formation.

Animals↗
PubMed1999

Progressive skin extension: clinical and histological evaluation of a modified procedure using Kirschner wires.

We describe a modification of a skin traction system for progressive skin extension before excision of skin lesions. The traction device consists of Kirschner wires and plastic straps. It results in more homogeneous traction and greater sparing of healthy skin as compared with the earlier silicone bar method. Moreover, the procedure results in lower rates of infection, skin necrosis and breakage of the cutaneous bridges. Histological changes to the treated skin area are similar to those obtained with skin expansion procedures.

Adolescent↗
PubMed2001

Alveolar ridge augmentation by distraction osteogenesis.

Distraction osteogenesis is an alternative method for reconstructing atrophic alveolar bone. Fourteen patients underwent vertical alveolar distraction by the LEAD SYSTEM-Endosseous Alveolar Distraction System (Stryker Leibinger, Kalamazoo, MI). An alveolar segmental osteotomy was carried out and the vertical distraction device was mounted. In patients with an extensive alveolar defect, two distraction devices were placed in order to better control the vector of elongation in both bone edges. The distraction was started on the fourth postoperative day at a rate of 0.8 mm/day for 10-16 days, followed by a consolidation period of 60 days. Vertical distraction osteogenesis (VDO) was completed successfully in all patients with segment lengths in the range of 8 to 13 mm and with an average of 10.3 mm. Subsequently, the devices were removed and 23 threaded titanium dental implants were placed for osteointegration. Earlier mineralization in the vertically distracted area was seen radiographically during the consolidation period. In a follow up of 6-20 months after the distraction, 22 implants were successfully osteointegrated while one implant failed due to improper distracted segment stability. As a result of alveolar distraction, a segment of mature bone was transported vertically in order to lengthen the crest for better implant anchorage, either for aesthetic purposes or for functional prosthetic requirements. The main advantages of VDO are: (1) augmentation of alveolar bone height with new bone formation and simultaneous expansion of the soft tissues; (2) no bone harvesting is necessary; (3) the technique has a lower morbidity rate compared with conventional techniques; (4) it makes the insertion of longer dental implants feasible.

Adolescent↗
PubMed1986

Temperature dependence of the tensile properties of interspinous ligaments of sheep.

The dependence on temperature of the tensile properties of interspinous ligaments was examined to establish whether in vitro studies at room temperature reflect behaviour in vivo at higher temperatures. Specimens consisting of sheep interspinous ligaments attached to their adjacent spinous processes were mounted in specially designed holding devices in an Instron material testing machine; the specimens were immersed in saline and tests were conducted at four temperatures between 19 degrees C and 46 degrees C. Control tests demonstrated the repeated testing to a load up to half the fail load did not affect the response of the ligaments. No difference was found in the mechanical characteristics of the ligaments at the different temperatures but the ligaments expanded at the higher temperatures, resulting in an increase in extension over which they demonstrated an initial low stiffness characteristic. Thus although temperature did not directly affect the response of the ligaments to load, the thermal expansion of the soft tissue elements may have implications for the function and mobility of spinal joints if measured at room rather than body temperature.

Animals↗
PubMed2002

Influence of stent design and deployment technique on neointima formation and vascular remodeling.

A variety of different stent types is available for the treatment of coronary stenosis. However, in-stent restenosis remains the major limitation for the use of these devices. Intracoronary ultrasound (ICUS) in addition to coronary angiography provides precise measurements of coronary wall dimensions during stent implantation and of intimal hyperplasia during follow-up. The extent of coronary injury during stent implantation was shown to play an important role in neointima formation. It is characterized by endothelial exposure, intima laceration, and media permeation. Stent-induced coronary injury has been considered to depend on stent design and stent strut size with consecutive deep wall laceration. ICUS analysis showed a correlation between the stent design and the amount of neointimal tissue proliferation. The role of adventitial remodeling in the process of restenosis is discussed controversially. Post-procedural stent expansion may provoke adventitial remodeling. The stent design and stenting strategy determines the extent of peri- and post-procedural coronary injury. Post-procedural coronary morphologic changes and changes of the stent geometry depend upon the stent design. Beside further modifications as the use of drug-eluting stents the decrease of stent-related vessel injury should be an important criterion for the development of future stent design.

Angioplasty, Balloon, Coronary↗
PubMed1989

[Changes at sutures and pariodontium of fixed teeth due to application of rapid contraction force in maxillary canines in dogs].

This study examines the histologic changes and the orthopedic effect, that might be expected after the application of an interrupted rapid contraction force with a skeleton type device, on the mid-palatal suture in the intercanine area, the sutures between the canines and the fixed teeth paradontium just after rapid contraction and after retention had been reached. Twenty young hybrid adult dogs, which were divided into five groups: a control group, a group of subjects just after rapid contraction, and retention groups at two, four and eight weeks. For the experimental groups, an expansion screw (No. 602-813), made by Dentaurum Co., was fixed between the maxillary canines and left there for two weeks to achieve a contraction with a total reduction of 3.52 mm. Measuring models, decalcified preparations (H.E. stain, Azan stain) and non-decalcified preparations (with hard tissue labeling medication) were used for the method of the study. The application of interrupted rapid contraction force at the maxilla produced a little body fusion on the mid-palatal suture only. However, the extent was very small, and disappeared during the retention. The fixed teeth showed tipping movements, but although there was a reduction of the maxillary width, it was still considered an indication and left a recognizable permanent complication. Thus the procedure is considered to be clinically valuable.

Animals↗
PubMed2000

Using the Ilizarov external fixation device for skin expansion.

Addressing war injuries requires tailoring treatment that provides the best functional and aesthetic results within a reasonable period of time. The authors report a young soldier who sustained a gunshot injury that caused an open fracture of the proximal tibia and patella (Gustilo type B-III). A local muscle flap could not be used, and thus the authors decided to use the already applied Ilizarov device for gradual expansion of the wound edge. The expanded skin covered the exposed fracture successfully, and later enabled solid union of the fracture. This reconstructive method seems to be an original solution for the management of open fractures, and additional proof that well-vascularized skin may be equivalent to a muscle flap, and may be considered for selected patients.

Adult↗
PubMed1995

Management of traumatic cutaneous defects by using a skin-stretching device.

We report on nine orthopedic patients who underwent skin stretching to close 10 acute soft-tissue defects. The skin surrounding all wounds was stretched sufficiently to enable a primary closure. At an average of 9 weeks postoperatively, 9 of the 10 wounds healed without any complications. One wound dehisced postoperatively, but subsequently healed by secondary intention. The skin-stretching device eliminated the need for local or distant flap reconstruction in five skin defects and skin grafting in five wounds. Donor morbidity was avoided, the cosmetic appearance of the skin was maintained, and the in-hospital course of these patients was shortened.

Adult↗
PubMed2002

Mechanical behavior of coronary stents investigated through the finite element method.

Intravascular stents are small tube-like structures expanded into stenotic arteries to restore blood flow perfusion to the downstream tissues. The stent is mounted on a balloon catheter and delivered to the site of blockage. When the balloon is inflated, the stent expands and is pressed against the inner wall of the coronary artery. After the balloon is deflated and removed, the stent remains in place, keeping the artery open. Hence, the stent expansion defines the effectiveness of the surgical procedure: it depends on the stent geometry, it includes large displacements and deformations and material non-linearity. In this paper, the finite element method is applied (i) to understand the effects of different geometrical parameters (thickness, metal-to-artery surface ratio, longitudinal and radial cut lengths) of a typical diamond-shaped coronary stent on the device mechanical performance, (ii) to compare the response of different actual stent models when loaded by internal pressure and (iii) to collect suggestions for optimizing the device shape and performance. The stent expansion and partial recoil under balloon inflation and deflation were simulated. Results showed the influence of the geometry on the stent behavior: a stent with a low metal-to-artery surface ratio has a higher radial and longitudinal recoil, but a lower dogboning. The thickness influences the stent performance in terms of foreshortening, longitudinal recoil and dogboning. In conclusion, a finite element analysis similar to the one herewith proposed could help in designing new stents or analyzing actual stents to ensure ideal expansion and structural integrity, substituting in vitro experiments often difficult and unpractical.

Computer Simulation↗
PubMed2006

Delayed primary closure of fasciotomy wounds with Wisebands, a skin- and soft tissue-stretch device.

BACKGROUND: Fasciotomy incisions for limb compartment syndrome usually cannot be closed primarily. The conventional method of wound closure with split-thickness skin grafting is effective, but it results in an insensate and disfiguring wound and is associated with donor site morbidity. We present our experience in delayed primary closure of fasciotomy wounds with Wisebands (WB), a skin- and soft tissue-stretching device. PATIENTS: Between 2000 and 2003, we treated 16 patients with extremity fasciotomy wounds for which primary closure was not feasible. RESULTS: The Wisebands devices achieved controlled stretching of the wound edges, including skin and underlying soft tissue, until primary closure was feasible. Fourteen patients (88%) had successful wound closure, two patients (12%) had minor wound complications that did not necessitate the removal of the device, and two patients had local wound complications (infection, intractable pain) and their devices were removed prematurely. Delayed primary closure was achieved at the initial surgery using intraoperative skin stretching in 3 of the 14 cases (21%). After a 2-year follow-up (1.3-4 years), the treated area showed stable scarring with good aesthetic outcome and no functional deficit. CONCLUSIONS: The Wisebands device facilitates closure of fasciotomy wounds with low complication rates and good functional and aesthetic outcome. Its application is simple and safe and requires a short learning curve. Nevertheless, appropriate patient selection, intraoperative judgment and close postoperative supervision are essential for optimal results.

Adult↗
PubMedDate not supplied

Corneal lathing using the excimer laser and a computer-controlled positioning system: Part I--Lathing of epikeratoplasty lenticules.

Precise lathing of epikeratoplasty lenticules is difficult to achieve with the cryolathe due to unpredictable expansion of the lathing tools and the corneal tissue during the freezing process. In addition, the procedure destroys all viable cells in the transplant thereby possibly contributing to the prolonged period of visual rehabilitation. Non-freezing techniques using the microkeratome or the rotor-trephine, on the other hand, are technically demanding, can cause mechanical damage during cutting or fixation, and, have not given consistently reproducible refractive results. A new system is presented that allows a variable laser ablation of donor corneas into lenticules for aphakic and myopic epikeratoplasty, as well as for lamellar keratoplasty. With the help of a computer-controlled positioning system that uses high-precision micropositioning elements (both translation and rotational stages) the donor cornea is moved, epithelial side down, in a holding device in front of a focused excimer laser beam (ArF, lambda = 193 nm). This photoablation lathing process assures the viability of the stromal cells in the lenticule in close approximation to the treated surface. The user friendly computer software allows the fast and convenient selection of a variety of parameters, such as the diameter of the optical zone, the shape of the wing zone, the refractive power, the central thickness of the lenticule and the overall contour of the transplant. The first laboratory data of lenticules prepared from human corneas with this "Excimer Laser Corneal Shaping System" are presented.

Cornea↗
PubMed1999

Induction of three-dimensional assembly of human liver cells by simulated microgravity.

The establishment of long-term cultures of functional primary human liver cells (PHLC) is formidable. Developed at NASA, the Rotary Cell Culture System (RCCS) allows the creation of the unique microgravity environment of low shear force, high-mass transfer, and 3-dimensional cell culture of dissimilar cell types. The aim of our study was to establish long-term hepatocyte cultures in simulated microgravity. PHLC were harvested from human livers by collagenase perfusion and were cultured in RCCS. PHLC aggregates were readily formed and increased up to 1 cm long. The expansion of PHLC in bioreactors was further evaluated with microcarriers and biodegradable scaffolds. While microcarriers were not conducive to formation of spheroids, PHLC cultured with biodegradable scaffolds formed aggregates up to 3 cm long. Analyses of PHLC spheroids revealed tissue-like structures composed of hepatocytes, biliary epithelial cells, and/or progenitor liver cells that were arranged as bile duct-like structures along nascent vascular sprouts. Electron microscopy revealed groups of cohesive hepatocytes surrounded by complex stromal structures and reticulin fibers, bile canaliculi with multiple microvilli, and tight cellular junctions. Albumin mRNA was expressed throughout the 60-d culture. A simulated microgravity environment is conducive to maintaining long-term cultures of functional hepatocytes. This model system will assist in developing improved protocols for autologous hepatocyte transplantation, gene therapy, and liver assist devices, and facilitate studies of liver regeneration and cell-to-cell interactions that occur in vivo.

Albumins↗
PubMed2005

Effect of temperature increase on the distensibility of porcine thoracic aorta.

The objective of the study was to investigate the temperature impact on the elasticity of porcine thoracic aorta. Under general anesthesia, 16 Landrace pigs were subjected to thoracotomy, and the descending thoracic aorta was removed and stored in normal saline. Serial sections of the vessel created cylindrical aortic specimens which were tested in a uniaxial tension device to determine the elastic properties of the aortic wall. In the control, Group A (n = 8), the aortic tissues were tested while immersed in normal saline bath of temperature TA = 37.0 +/- 0.5 degrees C, while in Group B, the temperature was TB = 40.0 +/- 0.5 degrees C. Each experiment took place only after the tissues had remained for 15 min in temperature TA or TB. For the results, the stiffness modulus of Group B showed a significant decrease (P < 0.05) at medium strain level deformation (e = 1, SB1 = 114 +/- 8 Pa) as well as at high strain level deformation (e = 2, SB1 = 1182 +/- 48 Pa) in comparison with the control, Group A (e = 1, SA1 = 147 +/- 15 Pa; e = 2, SA1 = 1479 +/- 64 Pa). It is concluded that temperature increase facilitates, in vitro, the expansion of descending thoracic aorta. We assume that thermal treatment may be another means against the stiffening of aorta, which calls for further research.

Animals↗
PubMed1987

The cytoskeletal mechanics of brain morphogenesis. Cell state splitters cause primary neural induction.

There is a functional device in embryonic ectodermal cells that we propose causes them to differentiate into either neuroepithelial or epidermal tissue during the process called primary neural induction. We call this apparatus the "cell state splitter." Its main components are the apical microfilament ring and the coplanar apical mat of microtubules, which exert forces in opposite radial directions. We analyze the mechanical interaction between these cytoskeletal components and show that they are in an unstable mechanical equilibrium. The role of the cell state splitter is thus to create a mechanical instability corresponding to the embryonic state of "competence" in an otherwise mechanically stable cell. When the equilibrium of the cell state splitter is disturbed so as to produce a slight contraction of the apical end, apical contraction continues and the distinctive columnar neuroepithelial cells are produced. A slight expansion from the equilibrium state, on the other hand, results in flattened epidermal cells. The calculated forces are consistent with the known constitutive and force-generating properties and morphology of microfilaments and microtubules, and with free tubulin concentrations. There are no free parameters in the analysis. The first cells to assume the neuroepithelial state lie over the notochord. Propagation of the neuroepithelial state (homoiogenetic induction) then proceeds via stretch-induced constriction of the apical microfilament rings, until a hemisphere is covered, at which point the high rate of change of the meridional stress component necessary for further propagation vanishes. The remaining cells are stretched somewhat by this process and become epidermis. A sharp boundary between the tissues is thus formed (explaining "compartmentalization" and the binary nature of differentiation in general). Normal induction apparently involves setup of the cell state splitters in all of the ectoderm cells, perhaps synchronously timed by global embryo tension. The initial transition of cells from the ectodermal to the neuroepithelial state begins at the notoplate, where cell attachments to the notochord may both cause basal actin deposition and significantly reduce the stress induced in the ectoderm by the global tension, biasing the notoplate cell state splitters toward the neuroepithelial state. Introduction of an organizer or other solid substrate (artificial inducer) elsewhere, to which ectodermal cells can adhere, may likewise have both of these effects. Differentiation to either epidermis or neuroepithelium is thus a mechanical event followed by the synthesis of specific proteins.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1997

Elevated compartmental pressures after closure of a forearm burn wound with a skin-stretching device.

A case of successful delayed primary closure of an upper extremity electrical blow-out injury is described using an alternative technique. The Sure-Closure skin-stretching device was used for permanent wound closure following serial debridement to protect the radial artery which was exposed over a distance of 21 cm. This method increases the options possible to achieve wound closure. However, the potential risks of this method include potentially high compartment pressures over a prolonged time in the postoperative period which requires close monitoring of limb perfusion.

Adult↗
PubMed1993

A skin-stretching device for the harnessing of the viscoelastic properties of skin.

A skin-stretching device that is designed to harness the viscoelastic properties of the skin using incremental traction is presented as an addition to the surgeon's armamentarium. It has proved to be of value in helping to close problematic areas of skin shortage which would otherwise have required more complicated procedures for their solution. It is simple in application and can even be put to use at the bedside. It consists of two pins that are threaded through the dermis of the wound margins on either side of the defect and which are in turn engaged by the hooks of the stretching device. The stretching force on the skin margins is spread over a wide area, thus preventing damage to the skin itself that individual hooks applied to the skin might cause. The device is employed over a duration of 20 to 30 minutes to 1 to 3 days depending on the condition of the skin adjoining the defect. The device can be applied over three different periods of time: (1) preoperatively (presuturing), lasting 1 to 2 days, (2) intraoperatively, extending over a period of 20 to 30 minutes, and (3) postoperatively (or delayed), which takes place over a time span of hours to 1 to 3 days. Five illustrative cases are presented.

Adult↗
PubMed2001

Proliferation of masseter myocytes after distraction osteogenesis of the porcine mandible.

PURPOSE: Long-term success of distraction osteogenesis depends on the ability of the surrounding soft tissues to tolerate distraction forces and to adapt to the resulting increase in skeletal length and volume. The hypothesis tested in this study was that mandibular elongation by distraction induces myocyte proliferation. MATERIALS AND METHODS: Unilateral mandibular angle osteotomies were performed in 16 Yucatan minipigs. The hemimandibles were lengthened using semiburied distraction devices (Synthes Maxillofacial, Paoli, PA) with 0-day latency, 1, 2, or 4 mm/d distraction rates, and a neutral fixation period of twice the gap size in days. In 2 additional animals, the dissection and osteotomies were performed, and distraction devices were placed without activation (sham control). At the end of neutral fixation, tissues were taken from masseter muscle overlying the osteotomy and the equivalent region on the unoperated side (contralateral control). Proliferation of myocytes was estimated using immunohistochemical localization with antibodies against proliferating cell nuclear antigen (PCNA). RESULTS: Muscle overlying the distracted mandible showed 6-fold more PCNA-positive myocytes (16.8% +/- 11.3%) than the contralateral control side (2.8% +/- 1.1%, P < .0001). In the 2 sham-control animals, there was a low index of PCNA-positive myocytes on both the osteotomy (2%, 5%) and the contralateral sides (1%, 2%). CONCLUSIONS: The results of this study suggest that distraction of the porcine mandible by the protocol described induces myocyte proliferation in the masseter muscle. A proliferative response may contribute to improved long-term stability of mandibular expansion by distraction osteogenesis.

Animals↗