Negative Pressure Wound Therapy in Necrotizing Fasciitis of the Head and Neck.

PURPOSE: Necrotizing fasciitis is a severe soft tissue infection that is uncommon in the head and neck region. Despite the advancement of care over the past few decades, the mortality rate remains high. Negative pressure wound therapy (NPWT), an advanced wound-healing technique, has become increasingly popular for a wide variety of complicated wounds. Since December 2015, we have used this technique in the management of necrotizing fasciitis of the head and neck. We report a consecutive case series treated with NPWT as the initial surgical procedure. MATERIALS AND METHODS: Seven patients who received a surgical diagnosis of necrotizing fasciitis of the head and neck underwent surgery under general anesthesia. After complete debridement, an NPWT device was applied for positive drainage of the involved areas. The drainage tube was connected to a central negative pressure system. The device was not replaced or removed until the infection was controlled. Then, a conventional drainage approach was used. RESULTS: Of the 7 patients, 6 underwent the surgical procedure and NPWT once; the remaining patient underwent these procedures twice. The infectious cavities showed a clean wound covered with healthy granulation formation during the removal of the NPWT device. The following course was uneventful. The mean time for wound healing was 17.3 ± 6.1 days. CONCLUSIONS: NPWT provides various advantages compared with conventional debridement and drainage, resulting in excellent clinical outcomes. This method could be recommended as an alternative approach in the management of necrotizing fasciitis in the head and neck region.

The variation of cancellous bones at lumbar vertebra, femoral neck, mandibular angle and rib in ovariectomized sheep.

This study aimed to compare the variation of cancellous bones at four skeletal sites: lumbar vertebra, femoral neck, mandibular angle and rib in ovariectomized sheep. Sixteen adult sheep were randomly divided into two groups: eight sheep were ovariectomized served as experimental group; the other eight untreated sheep were served as control group. Bone mineral density was assessed by dual-energy X-ray absorptiometry on lumbar vertebrae at baseline and twelve months after ovariectomy. After 12 months, lumbar vertebrae L3 and L4, femoral necks, mandibular angles and the fourth ribs were harvested for micro-CT scanning, histological analysis and biomechanical test. The results showed that bone mineral density of lumbar vertebra decreased significantly in twelfth month (p<0.05). The results of micro-CT showed that the bone volume/total volume decreased by 45.6%, 36.1% 21.3% and 18.7% in lumbar vertebrae, femoral necks, mandibular angles and ribs in experimental group (p<0.05) respectively. The trabecular number showed the same downtrend (p<0.05). Histological analysis showed trabecular area/tissue area decreased by 32.1%, 23.2% and 20.7% in lumbar vertebrae, femoral necks and mandibular angles respectively (p<0.05), but no significant difference in ribs. Specimens elastic modulus from lumbar vertebra, femoral neck and mandibular angle were 952±76MPa (628±70MPa), 961±173MPa (610±72MPa) and 595±60MPa (444±31MPa) in control group (experimental group) respectively. These datum indicated that the sensibility of cancellous bones to oestrogen deficiency in ovariectomized sheep was site-specific on a pattern as follows: lumbar vertebra, femoral neck, mandibular angle and rib.

Selection of optimal expansion angle and length of an expandable implant in the osteoporotic mandible: a three-dimensional finite element analysis.

PURPOSE: To identify from a biomechanical point of view the optimal parameters for an expandable implant in the osteoporotic mandible, a three-dimensional finite element model (FEM) of an expandable implant was created with variations in expansion angle and expansion length. MATERIAL AND METHODS: FEMs of osteoporotic posterior mandibular segments with an expandable implant were created. An axial load of 100 N and a buccolingual load of 30 N were applied to the implant. The expansion angle ranged from 0 to 4 degrees, and the expansion length ratio ranged from 1/6 to 5/6. The maximum equivalent stress (max EQV stress) in jawbone and the implant-abutment complex and the maximum displacement in the implant-abutment complex were evaluated. RESULTS: With changes in the expansion angle and expansion length ratio, the max EQV stress in cortical and cancellous bone increased by 12.4% and 73.9%, respectively, under axial loading, respectively, and by 38.6% and 69.1%, respectively, under buccolingual loading. The max EQV stress in the implant-abutment complex increased by 65.3% and 160% under axial and buccolingual loading, respectively. Maximum displacement in the implant-abutment complex increased by 3.66% and 19.73% under axial and buccolingual loading, respectively. CONCLUSION: Expansion angles and the expansion length ratio favored stress distribution in jawbone under axial and buccolingual loads, respectively. An expansion angle between 1.5 and 2.5 degrees and an expansion length ratio between 2/6 and 3/6 provided optimal biomechanical properties for an expandable implant in the osteoporotic mandible.

Evaluation of fixation of expandable implants in the mandibles of ovariectomized sheep.

PURPOSE: This study aimed to investigate the effects of an expandable implant (EI) in ovariectomized sheep. METHODS: The EI and taper implant (control group) were produced and placed in mandibles of ovariectomized sheep. Twelve weeks after implantation, resonance frequency analysis, biomechanical tests, histomorphometry, and micro-computed tomography were applied to detect the osseointegration in the 2 groups. RESULTS: The implant stability quotient values, maximal pullout forces, and bone-implant contact (BIC) were 60.3 ± 7.9, 511.0 ± 18.7 N, and 53.14% ± 4.56%, respectively, in the EI group and 58.3 ± 8.9, 394.5 ± 54.5 N, and 46.85% ± 5.04%, respectively, in the control group. There was no significant difference between the 2 groups in implant stability quotient values (P > .05); however, in the EI group the maximal pullout force and BIC were increased significantly (P < .05 and P < .01, respectively). Micro-computed tomography analysis showed that the bone volume/total volume ratio and trabecular number increased significantly (P < .01) and trabecular separation decreased significantly (P < .05) in the EI group. CONCLUSIONS: EI could improve osseointegration in osteoporosis after 12 weeks of implantation by increasing BIC around the implant and by supplying an extra osseointegration surface.

Effects of microrough and hierarchical hybrid micro/nanorough surface implants on osseointegration in ovariectomized rats: A longitudinal in vivo microcomputed tomography evaluation.

This study aimed to evaluate the effects of microrough and hierarchical hybrid micro/nanorough surface implants on osseointegration in ovariectomized rats at different time points. Implants with machined, microrough and hierarchical hybrid micro/nanorough surfaces were inserted into the distal femurs of ovariectomized Sprague-Dawley female rats. At weeks 0, 4, and 12 following implantation, in vivo microcomputed tomography (micro-CT) scanning was used to assess bone microarchitectural changes. After 12 weeks, all the rats were sacrificed, and the femurs with implants were harvested for histological analysis and pull-out test. For the Micro-CT analysis, the trabecular number and the bone volume ratio increased significantly in the microrough group (p < 0.01) and micro/nanorough group (p < 0.01) compared with the machined group. The trabecular separation decreased significantly in the micro/nanorough group (p < 0.01) compared with the other two groups. For the maximum pull-out forces and the bone-implant-contact analyses, significant statistical differences were found among the three groups, with the following sequence: micro/nanorough group > microrough group > machined group. The results indicate that the microrough and the hierarchical hybrid micro/nanorough surfaces of the implant can be beneficial to osseointegration under osteoporotic conditions, and the hierarchical hybrid micro/nanorough surface is more efficient.

Effects of hydrofluoric acid and anodised micro and micro/nano surface implants on early osseointegration in rats.

Our aim was to evaluate the effects of hydrofluoric acid and anodised micro and micro/nano surface implants on bony ingrowth in the earliest stage of implantation in rats. Sixty cylindrical screwed titanium alloy implants with machined, micro, and hierarchical hybrid micro/nano surfaces (n=20 in each group) were inserted into the distal femurs of 30 female Sprague-Dawley rats. In vivo microcomputed tomography (micro CT) was used to assess microarchitectural changes in the bone around the implants 2 weeks after implantation. All the animals were then killed and the femurs with implants harvested for histological analysis and pull-out testing. Micro CT analysis showed that the trabecular thickness and the bone:volume ratio (bone volume:total volume) (BV:TV) increased significantly in the micro/nano group compared with the other two groups, while the trabecular separation decreased significantly in the micro/nano group compared with the machined group. The mean (SD) bone-implant contacts (%) were 38.94 (9.48), 41.67 (8.71), and 51.49 (12.49) in the machined, micro, and micro/nano groups, respectively. The maximum pull-out forces (N) were 64.95 (6.11), 71.45 (7.15), and 81.90 (13.1), respectively. Both bone-implant contacts and maximum pull-out forces were significantly higher in the micro/nano group, but there was no significant difference between the micro group and the machined group. These data indicate that the hierarchical hybrid micro/nano surface of the implant can promote osseointegration in the earliest stage of implantation, and may be a promising option for further clinical use.

Effects of lateral cortical anchorage on the primary stability of implants subjected to controlled loads: an in vitro study.

Our aim was to evaluate the effects of lateral cortical anchorage on the primary stability of implants subjected to immediate loading. Implants were placed into bovine bones with monocortical anchorage (implant placed through the cortical bone of the crest) and bicortical anchorage (the crest cortical bone plus one cortical bone on the lateral side). Loads of 25N and 50N were applied to the implants in different cycles. The implant stability quotient (ISQ) was measured before and after the cyclic loadings. Under 25N load there was no difference in ISQ between 1800 cyclic loading and preloading, but the values decreased significantly after 3600 cyclic loading in both groups (p<0.05). Under a 50N load the ISQ value after 1800 and 3600 cyclic loading decreased in the monocortical group (p<0.05), but there was no difference between 1800 cyclic loading and preloading in the bicortical group, and the ISQ in the bicortical group was higher than in the monocortical group after 1800 cyclic loading (p<0.05). Our results suggest that the stability of implants with bicortical anchorage decreased more slowly under higher loads.

The biomechanical analysis of simulating implants in function under osteoporotic jawbone by comparing cylindrical, apical tapered, neck tapered, and expandable type implants: a 3-dimensional finite element analysis.

PURPOSE: This study compared the biomechanical behaviors of 4 implants in osteoporosis by 3-dimensional finite element analyses. MATERIALS AND METHODS: Finite element models (FEM) of posterior mandible segments with a cylindrical threaded implant, an apical tapered implant, a neck tapered implant (NTI), and an apical expandable implant were created. Bone segments with normal and osteoporotic biomechanical properties were used. Forces of 100 and 30 N were applied along the implant in axial and buccolingual (BL) directions, respectively. Maximum equivalent stresses in the jaw bone and maximum displacement in the implant-abutment complex were evaluated. RESULTS: In osteoporosis, compared with the cylindrical threaded implant, maximum equivalent stress in cortical bones with the apical tapered implant decreased by 10.1% and 6.57% under axial and BL loads, respectively. With the NTI, those values decreased by 10.72% and 7.87%. With the apical expandable implant, those values decreased by 11.3% and 9.60%. In cancellous bones, the maximum equivalent stress with the NTI decreased by 3.56% under a BL load. Maximum displacement in the implant-abutment complex decreased by 17.1% and 9.41% with an apical tapered implant under axial and BL loads, respectively. With the NTI, those decreased by 21.8% and 17.4%. Values in normal bone indicated better stress distributions and less displacement than those in osteoporotic bone. CONCLUSION: Stress distribution in the jaw bone and implant stability in osteoporotic bone were more sensitive to implant designs than those in normal bone. In osteoporotic bone, the expandable implant and the NTI showed better stress distribution, and tapered implants showed better stabilities.