Resorbable biotechnology for craniomaxillofacial surgery.
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Absorbable Implants↗
Biomedical subjects
B L Eppley
Publications and source records attributed to B L Eppley.
A buccal mucosal harvesting technique for urethral reconstruction.
PURPOSE: A step-by-step harvesting technique for buccal mucosa is described that maximizes graft yield while minimizing potential donor site morbidity in urethral reconstruction. MATERIALS AND METHODS: A specialized oral retractor was used to expose and retract the buccal mucosal lining of the oral cavity for graft harvesting in 12 patients. RESULTS: Adequate buccal mucosal graft size was obtained for each reconstruction. There were no oral donor site or urethral recipient site complications. CONCLUSIONS: This harvesting technique offers a simple and effective method for optimizing buccal mucosal graft harvests.
Adult↗
Alveolar cleft bone grafting (Part I): Primary bone grafting.
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Age Factors↗
Biomechanical testing of titanium self-tapping versus pretapped lag screw fixation of spiral metacarpal fractures.
Biomechanical tests of torsional loading and cantilevered bending were used to study the effects of varying screw size design of five different titanium miniscrews and microscrews in a metacarpal spiral oblique fracture model. Sixty-six fresh frozen human cadaveric metacarpal bones were subjected to torsional loading until failure, producing a spiral oblique fracture. The randomized fractured metacarpal bones were then repaired utilizing two 1.2-mm, 1.7-mm, or 2.3-mm self-tapping Leibinger lag screws; and 1.5-mm or 2.0-mm pretapped Synthes lag screws. Following repair, the specimens were then subjected to cantilevered bending or torsional loading. Failure torque and bending loads were then used to calculate failure stresses at the midshaft for torsional loading or at the proximal screw for cantilevered bending. Analysis of variance statistical analysis revealed that within the cortical thickness of bone studied, no significant difference in shear stress or axial stress was observed with increasing screw diameter and screw design.
Biomechanical Phenomena↗
A comparative biomechanical analysis of resorbable rigid fixation versus titanium rigid fixation of metacarpal fractures.
Linear (two-dimensional) and three-dimensional (3D) plating systems (Poly-Medics) composed of the resorbable copolymer of polyglycolic acid (PGA) and poly-l-lactic acid (PLLA) (Lactosorb) were studied in vitro. The plates were applied to osteotomized fresh frozen human cadaveric metacarpal bones that were then tested for torsional rigidity and three-point bending strength and rigidity. The results were compared to those from another study of two low-profile titanium plating systems (Leibinger and Synthes). Analysis of variance revealed that the linear-flat Lactosorb plate and screws had apex dorsal rigidity and force-to-displacement measurements equal to all but two of the titanium plates (3D). The 3D-flat Lactosorb plate had the highest torsional rigidity of the resorbable system, but it was only moderately rigid compared to the titanium plating systems. This in vitro biomechanical study of the copolymer PGA-PLLA plating system indicates that, in clinical applications, it may be better suited for metacarpal fractures rather than proximal phalangeal fractures due to the lower demands of torsional loading compared to apex bending.
Biomechanical Phenomena↗
A biomechanical analysis of the stability of titanium bone fixation systems in proximal phalangeal fractures.
Apex bending and torsional loading were utilized to study the effects of different plate design and thickness, and screw size and design on the rigidity and strength of seven different titanium mini- and microplates placed onto osteotomized proximal phalanges. One hundred forty-four fresh frozen human cadaveric proximal phalangeal bones underwent a mid shaft osteotomy followed by application of one of the following plates: (1) Synthes linear 1.5-mm five-hole plates, (2) Leibinger linear 1.2-mm five-hole or (3) 1.7-mm four-hole plates, or (4) Leibinger three-dimensional 1.2-mm four-hole, (5) 1.2-mm eight-hole, (6) 1.7-mm four-hole, or (7) 1.7-mm eight-hole plates. Three-point bending (apex dorsal or apex volar) and torsional loading were utilized for each plating configuration. Analysis of variance models of bone specimen width, depth, cortical thickness, and length revealed that increasing plate thickness was associated with increasing rigidity, but that the three-dimensional design yielded a higher relative rigidity except under apex volar loading.
Biomechanical Phenomena↗
Commentary on enhanced cranial bone healing.
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Animals↗
Resorbable bone fixation: its potential role in cranio-maxillofacial trauma.
The concept of biodegradable bone fixation devices, which provide sufficient rigidity to allow fracture healing and resorption thereafter, has significant appeal in cranio-maxillofacial trauma treatment; however, biodegradable bone fixation devices have not yet become available for clinical use in the craniofacial skeleton. This article reviews the obstacles in developing a resorbable polymer bone fixation system and describes the initial use of such a system in the treatment of cranio-maxillofacial trauma patients. It also discusses the potential role of a resorbable polymer bone fixation system in conjunction with the use of metal fixation in the management of facial fracture.
Absorbable Implants↗
Pediatric plastic surgery.
Pediatric plastic surgery has seen widespread advances during the past decade. These have been primarily in the biologic understanding of certain disease processes as well as in diagnostic and therapeutic technologies. These advances have contributed to a potential new array of treatment options for congenital deformities and traumatic injuries. This review identifies several of the most significant new trends and treatment concepts in pediatric plastic surgery from anesthesia to wound healing.
Anesthesia↗
Sympathetic blockade of isolated rat hindlimbs by intra-arterial guanethidine: the effect on blood flow and arterial-venous shunting.
In order to improve the understanding of the role of sympathetic nerve degeneration in reimplantation failure, the hindlimbs of eight rats (Group I) underwent near-complete amputation. The soft tissues of the hindlimb were transected at the proximal thigh with the femoral artery, vein and femur left intact. The femoral vessels were clamped and guanethidine was infused into a branch of the femoral artery of the right leg of each animal, while saline was injected into the left leg. The clamps were removed after 15 minutes. A baseline preoperative injection of radiolabeled microspheres was made, and subsequent injections at 6, 12, 18, and 24 hours postoperation. Twelve rats (Group II) were then used to assess the amount of arterial-venous shunting preoperatively (n = 6) and at 18 hours postoperation (n = 6), by venous sampling. Blood flow to both limbs increased postoperation, but there was significantly more flow in the guanethidine treated limb at 18 and 24 hours postoperation. The amount of shunting was approximately 50% in both limbs at 18 hours, as compared to 10% preoperation. These results highlight the potential benefit of guanethidine and other sympathetic blocking agents in reimplantation to increase blood flow, decrease tissue ischemia and increase anastomotic patency rates. They also suggest that sympathetic nerve degeneration did not affect the volume of arterial-venous shunting in this model, but the difference in blood flow was likely due to arteriolar vasospasm. Further study is needed to elucidate the clinical significance of sympathetic nerve degeneration in reimplantation failure.
Animals↗
Experimental assessment of small intestinal submucosa as a bladder wall substitute.
OBJECTIVES: This study determined the feasibility of promoting urinary bladder regeneration with porcine-derived small intestinal submucosa (SIS). METHODS: Twenty-two Sprague-Dawley rats underwent partial cystectomy with immediate bladder augmentation with SIS. Bladders were harvested for histologic evaluation at 2, 4, 8, 12, 24, and 48 weeks. RESULTS: Histologically at 2 weeks, there was infiltration of the graft material with viable host cells consisting of fibroblasts, macrophages, and blood vessels covered by complete mucosal urothelium comprised of transitional cells. During the next 10 weeks, collagen formation and maturation were noted, and by the end of 12 weeks, the SIS graft was comprised of a mature collagen matrix admixed with thinly scattered disorganized smooth muscle bundles and covered by normal urothelium. At 48 weeks, all three layers of the normal bladder (urothelium, smooth muscle, and serosa) were present and were grossly and microscopically indistinguishable from the normal rat urinary bladder. CONCLUSIONS: This study further supports the concept of bladder regeneration and suggests that SIS may be a viable material for bladder augmentations.
Animals↗
Mini and micro plating of phalangeal and metacarpal fractures: a biomechanical study.
Biomechanical testing was performed in a cadaver model to evaluate the effects of plate size and position on fracture stability using Leibinger mini and microplates applied on the proximal phalanx and metacarpal. Fresh frozen cadaveric metacarpal and proximal phalanges were subjected to a midshaft transverse osteotomy followed by application of titanium mini (1.7 mm screw diameter) and micro (1.2 mm screw diameter) plates/screws. For the metacarpal, a dorsal miniplate, a dorsal microplate, and bilateral microplates were used. For the proximal phalanx, similar plate configurations and sizes were used with the addition of a unilateral microplate. A three point bending model with both dorsal and palmar apex loading was used for all configurations. This study confirms that a dorsally applied miniplate provides the greatest rigidity to a dorsal apex load.
Biomechanical Phenomena↗
Comparative biomechanical stability of titanium bone fixation systems in metacarpal fractures.
The biomechanical properties of apex bending and torsional rigidity of 11 different titanium mini- and microplates (Leibinger and Synthes) were examined to evaluate the effects of plate design and thickness and screw size and design. Two hundred sixteen fresh-frozen human cadaveric metacarpal bones underwent a midshaft transverse osteotomy followed by application of one of the following plates: Synthes 1.5-mm and 2.0-mm five-hole linear plates; Leibinger linear 1.2-mm 5-hole, 1.7-mm 4-hole, 2.3-mm 4-hole plates; or Leibinger three-dimensional 1.2-mm 4-hole, 1.2-mm 8-hole, 1.7-mm 4-hole, 1.7-mm 8-hole, 2.3-mm 4-hole, and 2.3-mm 8-hole plates. The specimens were subjected to a three-point bending test with apex dorsal or apex volar loading or torsional loading. Analysis of variance statistical analysis revealed that increasing plate thickness and, more significantly, three-dimensional design were associated with increased rigidity.
Biomechanical Phenomena↗
Resorbable coupling fixation in craniosynostosis surgery: experimental and clinical applications.
The use of resorbable bone fixation devices composed of a copolymer of polyglycolic acid and polylactic acid were investigated in an animal model as well as in human application. We used resorbable plates and metallic microscrews in immature rabbits; plating of the coronal suture resulted in complete device resorption and increased interscrew distances (i.e., growth across the suture) after 8 postoperative months. In 20 infants with calvarial deformities, thin, straight resorbable plates were used for skeletal fixation after osteotomies and repositioning. A total of 231 fixation devices were implanted without complications after 12 postoperative months. These encouraging results have led to further clinical application in craniosynostosis deformities.
Animals↗
A comparison of resorbable and metallic fixation in healing of calvarial bone grafts.
The effects of a resorbable fixation plate composed of a polylactic acid-polyglycolic acid copolymer were compared with those of a metallic fixation plate of similar dimensions in an animal calvarial bone-graft healing model. Bilateral parietal bone grafts in 20 mature rabbits were fixed into position with a titanium mesh plate on one side and a polymer mesh plate on the other side. After 2, 6, 9, and 12 months, cross-sectional histology was used to compare osteotomy line healing, tissue response to the fixation material, and the amount of resorbable plate degradation. After 2 months, no changes in the dimensions of the resorbable plate were observed. The bone grafts fixed by both metal and polymer plates exhibited incomplete healing along the osteotomy lines. After 6 months, there was a 66 percent reduction in the dimensions of the resorbable plate and vertical shortening of screw length. Complete healing was seen along all osteotomy lines of both bone grafts. After 9 months, less than 1 percent of the resorbable mesh plate remained as a small film underneath a collagenous capsule. No polymer was seen within the confines of the screw holes. After 1 year, no evidence of polymer was seen either on the external cranial surface or within any of the screw holes. Bony union was observed across all osteotomy sites. The screw hole outlines persisted. The resorbable plate demonstrated fixation stability similar to that of metal with comparable osteotomy line healing. No adverse local inflammatory reactions were seen as the polymer composite progressed to complete degradation by 1 year.
Animals↗
Small intestinal submucosa: utilization for repair of rodent abdominal wall defects.
Prosthetic graft material is often used for the repair of abdominal wall defects that result from trauma, infection, neoplastic, or congenital deformities. A new material, porcine small intestinal submucosa, has been successfully used as an arterial and venous graft material in both canine and primate animal models with graft patency and infection rates equal to autologous vein. On the basis of these studies, small intestinal submucosa was used as a graft material for the repair of a 2 x 2-cm full-thickness defect of the muscle and fascia in the rodent abdominal wall (N = 11). Two animals were euthanized at 1 week, 2 weeks, 4 weeks, 2 months, and 3 months. At the time of euthanization, no abdominal hernias were noted and only minimal intra-abdominal adhesions were observed. One animal died on postoperative day 5 as a result of a wound dehiscence. Histological analysis of the excised abdominal wall hernia repairs revealed moderate initial inflammation but with incorporation of small intestinal submucosa with minimal inflammation at 2 months. No evidence of graft-versus-host rejection was noted with hematoxylin and eosin stains and light microscopy. Porcine small intestinal submucosa merits further study as a graft material for abdominal wall replacement.
Abdominal Muscles↗
Small intestinal submucosa: utilization as a wound dressing in full-thickness rodent wounds.
Wound dressings are used as a temporary wound covering to promote wound healing, control wound exudate, and decrease wound contamination as well as evaporative water loss. A new material, porcine small intestinal submucosa, has been used successfully as an arterial and venous graft in both canine and primate animal models with graft patency and infection rates equal to autologous vein. Based on these studies, small intestinal submucosa was used as a biological wound dressing in 20 x 20 mm full-thickness wounds made on Sprague-Dawley rats. In the controls (group I, n = 12), an acrylic frame (20 x 20 mm) was sutured to the wound edges, followed by placement of a thin polyurethane film. In the small intestinal submucosa-treated animals (group II, n = 12), the wound was covered with small intestinal submucosa and then with the acrylic frame and polyurethane film. The wounds were examined both visually and histologically at postapplication days 3, 7, 14, 28, 42 and 56. In addition, the wound contraction rate of 6 animals in both groups were recorded at postapplication day 0 and then at 1 week, 1 month, 2 months, and 3 months. Histological analysis (hematoxylin-eosin and periodic acid-Schiff stains) of the small intestinal submucosa-treated wounds revealed no host-versus-graft rejection and a rate of epithelialization equal to that of the control group. The wound contraction rate was statistically significant (higher; p < .05) in the control group compared to the small intestinal submucosa-treated group. Porcine small intestinal submucosa merits further study as both a biological wound dressing and as a substrate for cultured cells.
Animals↗
Experimental evaluation of small intestinal submucosa as a microvascular graft material.
The evaluation of porcine small intestine submucosa (SIS) in a microsurgical model was conducted using an interpositional graft in the rat femoral artery. The SIS grafts were fabricated from processed porcine material that was wrapped around a glass tube and oversewn longitudinally to produce a tubular structure. Of the 42 animals studied, 7 received grafts of untreated SIS (group I), 7 of the grafts were presoaked (PSH) in heparin (Group II), 7 animals were treated with systemic heparin prior to implantation of PSH-SIS (group III), 7 animals received SIS grafts crosslinked to heparin (group IV), 7 animals received SIS grafts crosslinked to urokinase (group V), and 7 animals received untreated autologous epigastric vein grafts (group VI). Patency was assessed postoperatively and selected grafts were evaluated by histology. All SIS grafts failed to maintain patency beyond the first postoperative hour. Histologic examination of the thrombosed graft surfaces revealed a smooth luminal surface with a thick layer of attached fibrin and platelets with a central occluding thrombus. The thickness of the induced fibrin layer appears to narrow intraluminal space significantly at the microvascular level. While having excellent success at vessel diameters greater than 3 mm, and in a variety of nonporcine animal models without xenographic rejection, SIS in this model was thrombogenic despite a favorable surface morphology as demonstrated by SEM. Even with use of heparin and urokinase SIS graft thrombosis occurred.
Animals↗