Deep circumflex iliac artery free flap in mandible reconstruction.
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Bone Transplantation↗
Biomedical subjects
Paul N Manson
Publications and source records attributed to Paul N Manson.
Multiplanar distraction osteogenesis of fibula free flaps used for secondary reconstruction of traumatic maxillary defects.
Traumatic maxillary bone loss, if not treated acutely, is accompanied by contracture of the overlying soft tissue envelope and loss of facial projection in three dimensions. Reconstruction aimed at replacing the bony architecture, expanding the soft tissue envelope and establishing a platform for dental rehabilitation can be accomplished in a staged approach. We present two patients who underwent replacement of missing maxillary segments with a free fibula flap, followed by distraction of the free fibula in three dimensions and eventual dental rehabilitation with osseo-integrated implants.
Adult↗
Variable cytocompatibility of six cell lines with photoinitiators used for polymerizing hydrogels and cell encapsulation.
The development of biocompatible photopolymerizing polymers for biomedical and tissue engineering applications has the potential to reduce the invasiveness and cost of biomaterial implants designed to repair or augment tissues. However, more information is needed about the cellular toxicity of the compounds and initiators used in these systems. The current study evaluates the cellular toxicity of three ultraviolet sensitive photoinitiators on six different cell populations that are used for engineering numerous tissues. The photoinitiator 2-hydroxy-1-[4-(hydroxyethoxy)phenyl]-2-methyl-1-propanone (Irgacure 2959) caused minimal toxicity (cell death) over a broad range of mammalian cell types and species. It was also demonstrated that different cell types have variable responses to identical concentrations of the same photoinitiator. While inherent differences in the cell lines may contribute to the variable cytotoxicity, a correlation between cellular proliferation rate (population doubling time) and increased cytotoxicity of the photoinitiator was observed. Cell lines that divided more quickly were more sensitive to photoinitiator-induced cell death. In summary, the photoinitiator Irgacure 2959 is well tolerated by many cell types over a range of mammalian species. Cell photoencapsulation strategies may be optimized to improve cell survival by manipulating proliferation rate.
Biocompatible Materials↗
The effect of incorporating RGD adhesive peptide in polyethylene glycol diacrylate hydrogel on osteogenesis of bone marrow stromal cells.
Advances in tissue engineering require biofunctional scaffolds that can not only provide cells with structural support, but also interact with cells in a biological manner. To achieve this goal, a frequently used cell adhesion peptide Arg-Gly-Asp (RGD) was covalently incorporated into poly(ethylene glycol) diacrylate (PEODA) hydrogel and its dosage effect (0.025, 1.25 and 2.5 mm) on osteogenesis of marrow stromal cells in a three-dimensional environment was examined. Expression of bone-related markers, osteocalcin (OCN) and Alkaline phosphatase (ALP), increased significantly as the RGD concentration increased. Compared with no RGD, 2.5 mm RGD group showed a 1344% increase in ALP production and a 277% increase in OCN accumulation in the medium. RGD helped MSCs maintain cbfa-1 expression when shifted from a two-dimensional environment to a three-dimensional environment. Soluble RGD was found to completely block the mineralization of marrow stromal cells, as manifested by quantitative calcium assay, phosphorus elemental analysis and Von Kossa staining. In conclusion, we have demonstrated that RGD-conjugated PEODA hydrogel promotes the osteogenesis of MSCs in a dosage-dependent manner, with 2.5 mm being optimal concentration.
Alkaline Phosphatase↗
Use of the serratus anterior free flap to treat a recurrent oroantral fistula.
We describe the successful use of the serratus anterior free muscle flap to obliterate a recurrent oroantral fistula in a 39-year old male who 19 years before this surgery had sustained a high velocity impact to his right face with multiple subsequent corrective surgeries. There was no complication from the serratus anterior free flap surgery and no postoperative scapular winging. The serratus anterior muscle is a versatile flap and ideal for various defects. It should be considered for obliteration of oroantral fistulas when no local or regional tissue is available because of previous surgery or trauma.
Adult↗
The orbit after Converse: seeing what is not there.
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History, 20th Century↗
Biomechanical analysis of hydroxyapatite cement cranioplasty.
A recent review of the authors' experience with hydroxyapatite (HA) cement cranioplasties revealed a high infection rate. During removal of these implants, all were loose and fractured. Forty percent of these patients had a history of minor trauma at the site of cranioplasty before experiencing infection. Minor trauma may fracture HA cranioplasties and result in infection. The purpose of this study is to determine the force to fracture full- and partial-thickness cranial defects reconstructed with HA cement and to compare peak loads of differing HA cement cranioplasty techniques. Standardized craniotomy defects were created in five fresh cadaver heads. Full-thickness defects were reconstructed with either rigid or flexible titanium mesh and then covered with HA cement. Partial-thickness defects were reconstructed with HA alone. After setting, a uniaxial impact was delivered to each of the defects. Peak loads were recorded, and defects were examined for evidence of fracture.Predictable fractures of the HA cranioplasties occurred at 1200 N in all full-thickness defects reconstructed with mesh and a thin layer of HA. Implant loosening and chipping was similar to what was seen clinically in the authors' patients with infections. Full-thickness defects in which titanium mesh was shaped like a cup and filled with a thick layer of HA resist fracture at 1200 N. Partial-thickness defects reconstructed with HA alone also do not fracture at this peak load. Patient selection, defect characteristics, and reconstructive techniques are factors that need to be considered before using HA cement for cranioplasty purposes.
Biomechanical Phenomena↗
Factors associated with anastomotic failure after microvascular reconstruction of the breast.
The prevalence of anastomotic failure resulting in return to the operating room and flap necrosis after microvascular breast reconstruction ranges from 1 to 5 percent. The purpose of this study was to review a set of factors that may be associated with this occurrence. Microvascular reconstruction of the breast was performed in 198 women from January of 1998 to July of 2002. The mean age for all women was 47.7 years. There were 158 unilateral and 41 bilateral reconstructions, for a total of 240 flaps. The specific flaps included the free transverse rectus abdominis musculocutaneous flap (n = 176), the deep inferior epigastric perforator flap (n = 58), and the superior gluteal artery perforator flap (n = 6). Upon recognition of anastomotic failure, women were immediately returned to the operating room. Factors that were considered relevant to anastomotic failure included the choice of recipient vessel, timing of reconstruction, previous chest wall radiation therapy, previous axillary lymph node dissection, tobacco use, diabetes mellitus, patient age, and hematoma. Patient follow-up ranged from 5 to 59 months. Descriptive statistics, Fisher's exact test, and exact logistic regression were used for analyses and to summarize data. Of the 240 flaps, return to the operating room was necessary for 20 (8.3 percent), total necrosis occurred in nine (3.8 percent), and the rate of flap salvage was 55 percent (11 of 20 flaps). Venous occlusion was responsible for 16 of the 20 returns and eight of the nine failures. Statistical analysis demonstrated that both return to the operating room and flap necrosis were significantly associated with venous occlusion, delayed reconstruction, and hematoma. Previous lymph node dissection and previous radiation therapy had only a weak association with return to the operating room. The results of this study demonstrate that venous occlusion is responsible for return to the operating room and flap necrosis in the majority of cases. Age, tobacco use, choice of recipient vessel, and diabetes mellitus were not associated with anastomotic failure. The significance of delayed reconstruction may be related to its frequent association with previous lymph node dissection and/or radiation therapy resulting in perivascular fibrosis.
Adult↗
Keloid scars are formed by polyclonal fibroblasts.
We hypothesized that keloids are composed of polyclonal fibroblasts and are not tumors derived from a single abnormal cell. That is, they are not monoclonal fibroblast neoplasms but rather are formed by intrinsically normal polyclonal fibroblasts that are responding to an abnormal extracellular signal. This hypothesis was tested using a polymerase chain reaction-based assay to examine X-chromosome inactivation and thereby determine clonality of keloid tissue. Six of 12 keloid samples analyzed were polyclonal. Three were genetically noninformative, and 3 were monoclonal. The presence of polyclonal specimens is consistent with our hypothesis and predicts that keloids result from intrinsically normal fibroblasts that are responding to an abnormal extracellular signal. This result can guide future genetic and molecular studies to identify this proposed abnormal regulatory signal, which we expect to be an important regulator of normal and diseased scarring.
Female↗
Spring-mediated mandibular distraction osteogenesis.
Successful performance of distraction osteogenesis requires rigorous patient compliance with a daily activation regimen of a percutaneous screw. Previous clinical studies have found that failure of patient compliance with this regimen is the most common complication leading to technical failure of the distraction process. The authors have developed an internalized spring-mediated device for mandibular distraction osteogenesis that can potentially abrogate the risks associated with patient compliance by allowing for automated distraction across an osteotomy. Twenty adult New Zealand White rabbits underwent unilateral mandibular osteotomy. A segment of nickel-titanium shape memory alloy reinforced at both ends with a pinball was fashioned into an inferiorly based arc and secured to the mandible with stainless steel wire. On postoperative day 12, spring activation commenced by cutting a wire binding the two pinballs to one another. Animals were observed for 6 weeks before they were killed. Radiographic studies and decalcified histologic analysis were performed on extracted mandibles. Temperature- and displacement-dependent properties of the shape memory alloy were also examined. Five animals were excluded from the study due to infection, nonunion, or device failure. A mean distraction of 1.2 mm in the distracted hemimandible relative to the nonoperated hemimandible was found (P <.001, two-tailed paired t test). The maximum distraction achieved in an experimental specimen using the spring distractor was 3.7 mm. There were no other histologic or radiographic differences found between study specimens and specimens subjected to traditional distraction methods. Biomechanical testing of the shape memory alloy revealed a temperature-dependent increase in force at body temperature compared with room temperature and a reduction in force with increased displacement of the spring. This study demonstrates the feasibility of spring-mediated distraction osteogenesis across an osteotomy. As the field of distraction osteogenesis matures, the next level of sophistication in the clinical development of devices will incorporate technology that permits fully internalized and automated distraction to occur.
Alloys↗
Cutis laxa: clinical experience and outcomes.
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Adolescent↗
Recalcitrant abdominal wall hernias: long-term superiority of autologous tissue repair.
Secondary repair of recurrent ventral hernia is difficult, and success depends on re-establishing the functional integrity of the abdominal wall. Current techniques used for closure of these defects have documented recurrence rates as high as 54 percent. The authors' 8-year experience utilizing variations of the components separation technique for autologous tissue repair of recalcitrant hernias emphasizes that recurrent or recalcitrant hernias benefit from the creation of a dynamic abdominal wall. A total of 389 patients were retrospectively identified as having abdominal wall defects, and 284 of these patients met the selection criteria. Study patients were grouped according to the type of surgical repair used. The recurrence rate was 20.7 percent over all study groups and was directly related to the extent of repair required. Group 1 patients (wide tissue undermining) had a recurrence rate of only 15 percent, while in group 2 (complete components separation), the recurrence rate was 22 percent. Group 3 patients (interpositional fascia lata graft) had a 29 percent recurrence rate. Time to recurrence was also significantly different across treatment groups, with study group 3 experiencing earlier hernia recurrence. The most frequent postoperative complication was wound infection, which was directly related to the repair performed. The relative odds of recurrence versus the risk factors of age, sex, perioperative steroid use, wound infection, defect size, and the presence of enterocutaneous fistula were studied with a logistic regression analysis. These factors did not possess statistical significance for predicting hernia recurrence. The preoperative presence of mesh was independently significant for hernia recurrence, increasing the relative odds 2.2 times (p = 0.01). Similarly, when other risk factors were controlled for, increasing the complexity of the treatment group, from study group 1 (wide tissue undermining) to study group 3 (interpositional fascia lata graft), also increased the odds of hernia recurrence 1.5-fold per group (p = 0.04). Average inpatient cost was $24,488. The length of inpatient stay ranged from 2 to 172 days (average, 12.8 days). The length of inpatient stay and costs were directly related to the extent of repair required. Using the analysis of variance test for multiple factors, the presence of an enterocutaneous fistula (p = 0.0014) or a postoperative wound infection (p = 0.008) independently increased the length of inpatient stay and hospital costs. A total of 108 successfully repaired patients were contacted by telephone and agreed to participate in a self-reported satisfaction survey. The patients noticed improvements in the appearance of their abdomen, in their postoperative emotional state, and in their ability to lift objects, arise from a chair or a bed, and exercise. These results suggest that recalcitrant hernia defects should be solved, when possible, by reconstructing a dynamic abdominal wall.
Abdominal Muscles↗
Infectious complications following breast reconstruction with expanders and implants.
The incidence of infection following breast reconstruction with expanders and implants ranges from 1 to 24 percent. Numerous factors associated with infection have been described; however, a one-variable at time setting and multifactorial analysis have not been performed. The purpose of this study was to analyze a set of factors that may predispose women to infection of the expander or implant. Between 1997 and 2000, a total of 168 implant reconstructions were performed in 130 women at a single institution. The mean age for all women was 48.2 years (range, 25 to 77 years). The factors that were analyzed included axillary lymph node dissection, chemotherapy, radiation therapy, tumor stage, timing of implant insertion, number of sides (unilateral versus bilateral), tobacco use, and presence or absence of diabetes mellitus. Statistical analysis was performed with stepwise logistic regression. Mean time to follow-up for all patients was 29 months (range, 12 to 47 months). Infectious complications occurred in 10 women (7.7 percent) and in 10 expanders or implants (5.9 percent). Infected implants were removed an average of 116 days following insertion (range, 14 to 333 days). Cultured bacteria included Staphylococcus aureus and Serratia marcescens. A significant association (p < 0.04) was detected between implant infection and radiation therapy. The chance for implant infection was 4.88 times greater for implants that were exposed to radiation therapy compared with those that were not. In addition, there was suggestive (p < 0.09) evidence that the chance of implant infection following lymph node dissection was 6.29 times higher than when no lymph nodes were removed. No significant association between implant infection and age, diabetes, tobacco use, tumor stage, timing of implant insertion, or chemotherapy was found.
Adult↗
Sentinel lymph node biopsy for the T1 (thin) melanoma: is it necessary?
The use of sentinel lymph node biopsy for the T1 melanoma is controversial. Recent reports have demonstrated that certain T1 melanomas are at increased risk for early regional metastases and late recurrence when compared with all thin melanomas. The purpose of this study was to review the authors' experience with wide excision and sentinel lymph node biopsy for certain patients with T1 melanoma. A retrospective analysis of 34 patients with T1 melanoma was completed over a 3-year period. Indications for sentinel lymph node biopsy included a Breslow thickness of less than or equal to 1 mm a Clark level of III or IV tumor ulceration, or tumor regression. Twenty-four patients met these criteria (13 men and 11 women). Mean age was 47.6 years (range, 23-88 years). Mean tumor thickness for all patients was 0.69 mm (range, 0.3-1.0 mm), 0.61 mm for the Clark level III patients (N = 15), and 0.72 mm for the Clark level IV patients (N = 9). Tumor ulceration was present in 1 patient and histological regression was present in 2 patients. Regional lymph node metastases were confirmed histologically in 2 of 24 patients (8.3%) in whom the thickness of the melanoma was 0.9 mm and 1 mm. Both patients have died of metastatic melanoma. No recurrence has been demonstrated in the remaining 22 patients at the 2 to 5-year follow-up. Current indications for sentinel lymph node biopsy for patients with T1 melanoma include tumors associated with Clark level IV or V invasion, ulceration, regression, a positive deep margin on initial biopsy, or previous melanoma. Acral lentiginous melanoma associated with at least a Clark level III invasion warrant sentinel lymph node biopsy. Superficial spreading or nodular melanoma larger than 0.9 mm should include sentinel lymph node biopsy regardless of other associated histological factors.
Adult↗
Callus stimulation in distraction osteogenesis.
Distraction osteogenesis has been described as in vivo tissue engineering. The ability to stimulate this process for the repair of bony defects or lengthening of congenitally shortened facial structures is likely to significantly impact the field of craniofacial surgery. The purpose of this study was to determine whether mechanical stimulation of the distracted rabbit mandible would accelerate the maturation of the bony callus when applied during the early consolidation period. Twenty adult New Zealand White rabbits underwent unilateral mandibular osteotomy. A uni-directional internal distractor device (Synthes, Paoli, Pa.) was positioned along a plane perpendicular to the line of osteotomy. After a 7-day latency period, distraction was commenced at a rate of 1.0 mm/day for 12 days in all animals. In a control group of 10 rabbits, a consolidation period of 8 weeks was observed before they were killed. In the experimental group of 10 rabbits, daily alternate compression and distraction of 1 mm (sequential compression and distraction) was performed for 3 weeks followed by a 5-week period of rigid fixation. Each animal received a dose of a fluorescent label at three different time points during the study: at the end of the distraction period, 3 weeks after the completion of the distraction phase, and 3 days before it was killed. All animals were killed 8 weeks after the completion of the distraction phase. Undecalcified histologic analysis and 3-point bending tests to failure were performed on the extracted mandibles. The results of the experimental and control groups were compared. Four animals in the control group and three animals in the experimental group were excluded from the study because of screw loosening resulting in distractor dislodgment or because of infection. On histologic analysis, cortical thickness at the center of the callus was found to be significantly greater in the experimental group compared with the control group when normalized to the contralateral hemimandible (83 percent versus 49 percent, respectively; p < 0.007). The ratio of cortical to cancellous bone in the distracted callus was uniformly found to be greater in the experimental specimens. The mineral apposition rate was calculated by using fluorescence microscopy and found to be significantly greater in the experimental group both during the period of sequential compression and distraction (3.2 microm/day versus 2.1 microm/day, p = 0.02) and after the period of sequential compression and distraction (1.4 microm/day versus 1.1 microm/day, p = 0.006). Mechanical testing revealed no significant differences in bending strength or stiffness between experimental or control groups (p = 0.54 and 0.47, respectively). This study has demonstrated that daily alternating compression and distraction of 1 mm amplitude during the early consolidation period has a stimulatory impact on callus formation with respect to osteoblastic activity, remodeling, and maturation of bone. Optimal timing and amplitude of sequential movement, long-term biomechanical differences, and molecular pathways have yet to be elucidated.
Animals↗
Facial fractures from dog bite injuries.
Dog bites are commonly associated with soft-tissue injury to the face but rarely result in facial fractures. This article reports six new cases of facial fractures associated with dog bites and reviews additional cases reported in the literature. The demographics of the patients attacked, the location of facial fractures, and the characteristics of associated soft-tissue injuries or complications developing from the dog bite are described. With six new cases and 10 from the literature, this article reviewed a total of 16 cases involving 27 facial fractures. Eighty-seven percent of the cases involved children less than 16 years of age. The periorbital or nasal bones were involved in 69 percent of the cases. Lacerations were the most frequently associated soft-tissue injury. Additional injuries included facial nerve damage, lacrimal duct damage requiring stenting and reconstruction, ptosis from levator transection, and blood loss requiring transfusion. Although facial fractures are not commonly considered to be associated with dog bite injuries, the index of suspicion for a fracture should be raised when the injury occurs in a child, particularly when injury occurs near the orbit, nose, and cheek.
Animals↗
Contour abnormalities of the abdomen after transverse rectus abdominis muscle flap breast reconstruction: a multifactorial analysis.
Contour abnormalities of the abdomen after transverse rectus abdominis muscle (TRAM) flap breast reconstruction occur with all methods of flap elevation and include lower and upper abdominal laxity, epigastric fullness, and hernia. This study is a retrospective analysis of 101 women comparing the many variables that may contribute to an abnormal contour. Statistical analysis comparing the free, pedicled, unilateral, bilateral, muscle-sparing, and non-muscle-sparing flaps was completed using logistic regression. Associated factors, including diabetes mellitus, tobacco use, use of mesh, and prior abdominal operations, were incorporated. Abnormal abdominal contour was present in 13 of 101 women and included 16 specific abnormalities. These included upper abdominal bulge in three women, lower abdominal bulge in eight, and epigastric fullness in five. No woman developed a hernia. Bifactorial analysis demonstrated a significant increase in abnormal contour for the pedicled, bilateral, and non-muscle-sparing TRAM groups when compared with their countervariable groups (free, unilateral, and muscle-sparing TRAM, respectively; p < 0.05). Multifactorial analysis demonstrated a significant increase in abnormal contour in two subgroups (p < 0.05). An analysis of associated factors demonstrated a significant increase in abnormal contour for the bilateral TRAM in the presence of a prior lower midline incision (p < 0.05).
Abdomen↗
Contour abnormalities of the abdomen after breast reconstruction with abdominal flaps: the role of muscle preservation.
The purpose of the present study was to determine whether contour abnormalities of the abdomen after breast reconstruction with abdominal flaps are related to the harvest of the rectus abdominis muscle. Abdominal contour was analyzed in 155 women who had breast reconstruction with abdominal flaps; 108 women had free transverse rectus abdominis muscle (TRAM) flaps, 37 had pedicled TRAM flaps, and 10 had deep inferior epigastric perforator (DIEP) flaps. The reconstruction was unilateral in 110 women and bilateral in 45 women. Three methods of muscle-sparing were used; they are classified as preservation of the lateral muscle, preservation of the medial and lateral muscle, or preservation of the entire muscle. One of these three methods of muscle-sparing was used in 91 women (59 percent) and no muscle-sparing was used in 64 women (41 percent). Postoperative contour abnormalities occurred in 15 woman and included epigastric fullness in five, upper bulge in three, and lower bulge in 10. One woman experienced two abnormalities, one woman experienced three, and no woman developed a hernia. Of these abnormalities, 11 occurred after the free TRAM flap, seven after the pedicled TRAM flap, and none after the DIEP flap. Bilateral reconstruction resulted in 11 abnormalities in nine women, and unilateral reconstruction resulted in seven abnormalities in six women. chi2 analysis of the free and pedicled TRAM flaps demonstrates that muscle-sparing explains the observed differences in upper bulge and upper fullness (p = 0.02), with a trend toward significance for lower bulge (p = 0.06). chi2 analysis of the free TRAM and DIEP flaps does not explain the observed difference in abnormal abdominal contour. Analysis of muscle-sparing and non-muscle-sparing methods demonstrates that the observed difference between the techniques is only explained for a lower bulge after the bilateral free TRAM flap (p = 0.04).
Abdomen↗