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Necrotizing fasciitis is a rare and often fatal soft-tissue infection involving the superficial fascial layers of the extremities, abdomen, or perineum. Necrotizing fasciitis typically begins with trauma; however, the inciting event may be as seemingly innocuous as a simple contusion, minor burn, or insect bite. Differentiating necrotizing infections from common soft-tissue infections, such as cellulitis and impetigo, is both challenging and critically important. A high degree of suspicion may be the most important aid in early diagnosis. Prompt diagnosis is imperative because necrotizing infections typically spread rapidly and can result in multiple-organ failure, adult respiratory distress syndrome, and death. Although group A Streptococcus is the most common bacterial isolate, a polymicrobial infection with a variety of Gram-positive, Gram-negative, aerobic, and anaerobic bacteria is more common. Orthopaedic surgeons are often the first physicians to evaluate patients with such infections and therefore need to be familiar with this potentially devastating disease and its management. Prompt diagnosis, immediate administration of broad-spectrum antibiotic coverage, and emergent aggressive surgical debridement of all compromised tissues are critical to reduce the morbidity and mortality of these rapidly progressing infections.

To evaluate the effects of pulsatile lavage and bulb syringe irrigation on fracture healing in vivo.Randomized prospective trial in an animal model.Medical school orthopaedic department.Thirty New Zealand white rabbits.The control group (C) underwent osteotomy of the medial femoral condyle, stabilization, and closure. The bulb syringe and pulsatile lavage groups underwent the same procedure as group C, with the addition of irrigation with one liter of normal saline via a bulb syringe (B) or a pulsatile lavage system (P). Animals were administered two fluorescent bone stains: xylenol orange at the time of operation, and calcein green one week postoperatively. Animals were euthanized two weeks postoperatively and femurs were retrieved for histological analysis.Union was determined by examination of microradiographs under light microscopy. The viability of bone along the fracture site was determined by evaluation of xylenol orange and calcein green staining under fluorescent microscopy. The density of new bone formed in the osteotomy site was assessed by computerized digitization of standardized regions of the proximal and distal osteotomy.Xylenol orange bands were present a mean of 66 +/- 8 percent (mean +/- standard error of the mean), 65 +/- 6 percent, and 44 +/- 5 percent of the distance along the osteotomy in groups C, B, and P, respectively (p0.001). Calcein green bands were present throughout the osteotomy site in all specimens. Calcified new bone was present in 62 +/- 4 percent, 58 +/- 7 percent, and 41 +/- 9 percent of the area measured in groups C, B, and P, respectively (p = 0.07). Twenty percent of the osteotomies in groups C and B did not unite, compared with 30 percent in group P (p0.5).Pulsatile lavage irrigation of fresh intraarticular fractures in rabbits has a detrimental effect on early new bone formation; this effect, however, is no longer apparent two weeks following irrigation. While this study evaluated the effects of pulsatile lavage irrigation in noncontaminated fractures without extensive soft tissue injury, the detrimental effects observed on early new bone formation may translate to an increased risk of nonunion in the setting of a contaminated open fracture with extensive soft tissue injury. Based on the results of this investigation, the selective use of pulsatile lavage irrigation appears warranted. In the absence of gross wound contamination, irrigation with a bulb syringe appears less likely to impair fracture healing than does pulsatile lavage irrigation. Expansion of the model used in this study to include bacterial contamination and soft tissue crushing may further elucidate the effects of pulsatile lavage irrigation on fracture healing.

Locally applied antibiotic therapy is gaining popularity for the treatment of infections associated with open fractures and posttraumatic osteomyelitis. With use of local techniques, ciprofloxacin levels as high as 1,300 microg/ml, or over 200 times the bone levels achieved with intravenous administration, have been reported. To study the possible effects of ciprofloxacin on bone, osteoblast-like cells from the MG-63 human osteosarcoma cell line were studied. The cells were grown in antibiotic-free media and exposed to concentrations of ciprofloxacin at 0, 10, 100, 200, and 1,000 microg/ml to establish an initial dose-response curve. Media containing the appropriate dose of ciprofloxacin were changed every 24 hours. Cell number and [3H]thymidine incorporation per cell were determined at 0, 24, and 72 hours. A second dose-response curve was performed at concentrations of 0, 10, 20, 40, and 80 microg/ml. Three experiments, each with four observations, were performed. The results of this study demonstrated that ciprofloxacin caused significant decreases (p < 0.05) in cell number at 40 microg/ml at 24 hours and 20 microg/ml at 72 hours. [3H]thymidine incorporation per cell decreased significantly at levels of 80 microg/ml at 24 hours and 20 microg/ml at 72 hours. The authors conclude that reported local levels of ciprofloxacin seen in vivo inhibit the proliferation of human osteoblast-like cells in vitro.

OBJECTIVES Recently, radiation-independent aiming devices for the tibia that compensate for insertion-related implant deformation have been developed, but the benefits of such systems have not been determined. This study prospectively evaluated the duration of the nailing procedure, the length of radiation time, and the accuracy of interlocking screw placement when using a radiation-independent distal aiming device (DAD) versus the freehand technique (FHT). MATERIALS AND METHODS In an oblique cadaveric tibial fracture, a surgeon inexperienced in both techniques (DAD and FHT) performed statically locked intramedullary nailing. RESULTS For the DAD and the FHT, respectively, the total operation time was 25.4 +/- 11.3 (mean +/- standard deviation) versus 30.9 +/- 14.3 minutes (p = 0.029), the distal locking time was 16.7 +/- 8.6 versus 21.9 +/- 10.5 minutes (p = 0.004), the total fluoroscopy time was 9 +/- 5 versus 93 +/- 34 seconds (p < 0.0001), the distal locking fluoroscopy time was zero versus 88 +/- 33 seconds (p < 0.0001), and the screw wear was -0.7 +/- 5.2 versus 26.8 +/- 31.6 micrometers (p = 0.001). The failure rate was 1.6 percent (one of sixty screws) in both groups. CONCLUSION These results suggest that the DAD can eliminate the need for radiation during placement of distal interlocking screws.

Twenty-four cannulated sacroiliac screws were placed bilaterally into 12 cadaveric pelvi (12 titanium screws and 12 stainless-steel screws) and were imaged using conventional and multiplanar reconstructed computed tomography.To determine whether sacroiliac screw position assessment relative to the neuroforamen is enhanced by: 1) computed tomography using multiplanar reconstructions and 2) the use of titanium screws rather than stainless-steel screws.To the authors' knowledge, there have been no prior studies demonstrating the accuracy of multiplanar computed tomography compared with that of conventional (axial) tomography in determining the position of sacroiliac screws relative to the neuroforamen. Although titanium screws have been shown to have less scatter than stainless-steel screws, the effect of alloy composition on the radiographic accuracy of interpreting the screw position relative to the sacral neuroforamen is unknown.Screws were deliberately placed into: position A, in which the screw did not violate the neuroforamen; position B, in which the threads of the screw came within 3 mm of the neuroforamen; and position C, in which the screw clearly was nearly centered in the neuroforamen. The degrees of accuracy in assessing screw position relative to the neuroforamen using conventional (axial) images and using multiplanar reconstructed images were compared.The axial images were accurate in determining screw position relative to the neuroforamen in 50% of cases in which titanium screws were used and in 42% of cases in which stainless-steel screws were used. The corresponding values for multiplanar reconstructions were 92% for cases in which titanium screws were used and 67% for cases in which stainless-steel screws were used. The accuracy of multiplanar reconstructions was statistically better than that of axial images (P0.05). Metallic scatter was increased in stainless-steel screws.The results of this study suggest that the use of computed tomography with multiplanar reconstruction improves accuracy in determining sacroiliac screw position relative to the neuroforamen. The assessment of screw position may be facilitated using titanium screws.

'Radiation-independent' aiming systems for the placement of interlocking screws in intramedullary tibial nails have failed because of insertional related nail deformation. Prior to the development of these distal aiming systems, the variable position of the nails' interlocking holes after insertion must be known. In this study, the amount and direction of implant deformation of solid stainless-steel tibial nails (diameters of 8 and 9 mm, n = 20) were analyzed. Measurement of implant deflection (three translations, three angles) in the center of distal transverse locking hole was performed with a three-dimensional-magnetic motion tracker system after nail insertion in paired human cadaver tibiae. The results showed combined mean lateral translation of the 8 and 9 mm nails (n = 20) of -4.5 +/- 3.5 mm (range: 14.3 mm) and dorsal translation -7.8 +/- 5.8 mm (range: 19.2 mm). The combined mean rotational deformation about the longitudinal axis of the nail was 0.3 +/- 0.7 degree (range: 2.4 degrees). The authors conclude that a simple aiming arm, mounted on the proximal nail end alone, is not sufficient to provide accurate distal aiming.

A cadaver arterial injection study was performed to analyse the vascular supply to the femur and to study the effects of two surgical plating techniques on femoral vascularity. A 16-hole LC-DCP was applied on the intact femora of five fresh human cadavers. On one side, the plate was inserted using a conventional lateral plate osteosynthesis (CLPO) technique with elevation of the vastus lateralis muscle to expose the shaft. On the contralateral side, the plate was inserted percutaneously beneath the muscle using a minimally invasive plate osteosynthesis (MIPO) technique. After plating, blue silicone dye was injected through the common femoral artery. Cadaveric dissection was then performed to identify the femoral perforating arteries (PAs) and the nutrient artery (NA) of the femur. The pattern of periosteal filling and medullary perfusion of the injected dye was analysed and the topography of the PAs and NA was determined. CLPO placed the PAs and NA of the femur at risk. MIPO maintained the integrity of the PAs and NA and was associated with superior periosteal and medullary perfusion. The results of this study indicate that MIPO is superior to the CLPO in maintaining arterial femoral vascularity and perfusion.

The accuracy of templates used for the preoperative planning of the fixation of intramedullary fractures depends on radiological magnification. To study the accuracy of these templates, we randomly selected 100 femoral and 100 tibial radiographs taken after stabilisation by an intramedullary nail using a standard technique. We then compared the known nail length with the corresponding measurements on the radiographs. The mean magnification factor for the femur was 9% and for the tibia 7%; these differ considerably from the range of magnification of the manufacturers’ templates (femur, 15% to 17%; tibia 10% to 15%). We conclude that templates are unreliable for the selection of implant length and that this should be done by intraoperative measurements.

OBJECTIVE: The objective of this study was to analyse the position of the distal interlocking holes of an unreamed solid tibial nail relative to the adjacent cortices of the tibial bone. DESIGN. IN VITRO: and in vivo radiographic-morphometric analysis. BACKGROUND: To date, 'radiation-independent' intramedullary distal interlocking aiming systems have not been successful, primarily because proximally mounted aiming devices cannot account for the deformation of the nail during insertion; therefore the distal interlocking holes relative to the adjacent cortices must be understood. METHODS: A two-dimensional radiographic-morphometric analysis was performed in 40 tibiae after in vitro (n = 20) and in vivo (n = 20) implantation of unslotted stainless steel unreamed 8- and 9-mm diameter intramedullary nails. RESULTS: The combined in vitro and in vivo results showed average distances between the upper distal transverse hole and the anterior aspect of the tibia of 12.3 mm (SD 1.7 mm; variance 2.9 mm(2); range 7.6 mm). CONCLUSIONS: The distances between the upper distal transverse hole and the anterior aspect of the tibia are the most reliable parameters of distal nail hole position. RELEVANCE: For a 'radiation-independent' distal interlocking aiming system for unreamed intramedullary tibial nails to be successful, it could take advantage of the relatively constant distance between the anterior cortex and the most proximal distal screw hole.

While gap defect models provide greater graft stability and are more representative of many clinical situations than segmental defect models, the healing in these models has not been well documented. To study the histologic course of cancellous bone graft healing in a long bone gap defect, 12 adult mongrel dogs were killed in groups of two at 1, 2, 3, 4, 6, and 12 weeks. Graft incorporation in these dogs was studied using macro- and microradiography, histologic sections, and computer-assisted digital surface analysis ; results are described. Unlike that seen in segmental defect models, the pattern of repair in a cancellous bone grafted gap defect provides consistent healing at 12 weeks and follows the same healing process seen with stable defects.

Introduction: Similarities between skeletal formation and repair have led to the theory that adult fracture repair may parallel development. We hypothesize that since the mandible is derived from cranial neural crest (CNC) and forms via intramembranous ossification, non-stabilized mandibular fractures will heal in a similar fashion. Methods: Non-stabilized osteotomies were created in the right hemi-mandible of adult male mice. Mandibles were harvested at 7, 14, 21, and 28 days and processed for histology. Ossification was assessed and the presence of cartilage determined using histology and in situ hybridization (ISH). To determine the embryologic origins of the regenerate, transgenic mice were generated where CNC cells express GFP constitutively under the Wnt-1 promoter. Fractures were created as described above and processed for frozen section. CNC cells were localized using immunohistochemistry (IHC) for GFP. Closed, non-stabilized tibial fractures were also performed to determine the presence, if any, of CNC-derived cells in appendicular skeletal fractures. Results: In contrast to non-stabilized fractures of the appendicular skeleton, mandibular fractures healed predominantly via intramembranous ossification, with minimal and delayed cartilage production seen via histology and collagen2 ISH. IHC for GFP revealed that the mandibular fracture callous and regenerate was comprised primarily of GFP+, CNC-derived cells. In contrast, the tibial fracture callous was devoid of any CNC-derived cells. Conclusions: These data suggest that mandibular fractures heal by recapitulating their developmental program. These findings have important implications for designing appropriate cell-based approaches to craniofacial regeneration.

The effect of tobramycin on osteoblasts was studied. Osteoblast-like cells from the MG-63 human osteosarcoma cell line were grown in antibiotic-free media and exposed to concentrations of tobramycin: first at order of magnitude intervals between 0 and 10,000 micrograms/ml, and then at closer intervals between 100 and 1,000 micrograms/ml to more accurately define toxic levels. Cell number and 3H-thymidine incorporation at 0, 24 and 72 h were determined. Similarly, primary cultures of rat osteoblasts were exposed to the same concentrations of tobramycin to confirm the validity of the MG-63 cell line as a model for nontransformed cells. The results of this study demonstrate that local levels of tobramycin of < or = 200 micrograms/ml have little or no effect on osteoblast replication. Concentrations of 400 micrograms/ml significantly decreased cell replication, and concentrations of 10,000 micrograms/ml caused cell death. Results obtained with primary rat osteoblast cultures were similar to those obtained from the MG-63 cultures at the tested tobramycin concentrations.

Numerous factors can affect skeletal regeneration, including the extent of bone injury, mechanical loading, inflammation and exogenous molecules. Bisphosphonates are anticatabolic agents that have been widely used to treat a variety of metabolic bone diseases. Zoledronate (ZA), a nitrogen-containing bisphosphonate (N-BP), is the most potent bisphosphonate among the clinically approved bisphosphonates. Cases of bisphosphonate-induced osteonecrosis of the jaw have been reported in patients receiving long term N-BP treatment. Yet, osteonecrosis does not occur in long bones. The aim of this study was to compare the effects of zoledronate on long bone and cranial bone regeneration using a previously established model of non-stabilized tibial fractures and a new model of mandibular fracture repair. Contrary to tibial fractures, which heal mainly through endochondral ossification, mandibular fractures healed via endochondral and intramembranous ossification with a lesser degree of endochondral ossification compared to tibial fractures. In the tibia, ZA reduced callus and cartilage formation during the early stages of repair. In parallel, we found a delay in cartilage hypertrophy and a decrease in angiogenesis during the soft callus phase of repair. During later stages of repair, ZA delayed callus, cartilage and bone remodeling. In the mandible, ZA delayed callus, cartilage and bone remodeling in correlation with a decrease in osteoclast number during the soft and hard callus phases of repair. These results reveal a more profound impact of ZA on cartilage and bone remodeling in the mandible compared to the tibia. This may predispose mandible bone to adverse effects of ZA in disease conditions. These results also imply that therapeutic effects of ZA may need to be optimized using time and dose-specific treatments in cranial versus long bones.

Local deposition of antibiotics has became increasingly popular in the management of open fractures or osteomyelitis, and several substances have been employed as the vehicle for delivery. Although the elution characteristics of some substances have been documented, a comparative study of the characteristics of the commonly used substances could establish the clinical indications for particular vehicles. Cylindrical pellets of uniform size (6 × 4 mm) were prepared from bone graft (BG), demineralized bone matrix (DBM), plaster of Paris (POP), or polymethylmethacrylate (PMMA), with 25 mg of tobramycin/g of substance in each pellet. The pellets were suspended in phosphate buffered saline, and the antibiotic concentration in the buffer was determined at various time intervals by an enzyme immunoassay. BG and DBM eluted 70 and 45% of their antibiotic load by 24 h, and negligible amounts were detected at 1 week; POP released 17% of its load by 24 h, with trace amounts detected at 3 weeks; and PMMA eluted 7% at 24 h, with trace amounts detected for as long as 14 days. These findings suggest that the optimal vehicle for local deposition of antibiotic depends on the clinical setting. BG and DBM may be best employed when brief antibiotic coverage is required (as for acute contaminated open fractures), whereas POP and PMMA may be better suited for long-term coverage (such as for established osteomyelitis).

The effect of cefazolin and vancomycin on osteoblast-like cells was studied. Cells from the MG-63 human osteosarcoma cell line were grown in antibiotic free media and exposed to concentrations of cefazolin and vancomycin at order of magnitude intervals between 0 and 10,000 microg/ml. For cefazolin, a second interval was performed between 100 and 1000 microg/ml to define toxic levels more accurately. Cell number and 3H-thymidine incorporation at 0, 24, and 72 hours were determined. The results of this study show that local levels of vancomycin of 1000 microg/ml and less have little or no effect on osteoblast replication, and concentrations of 10,000 microg/ml cause cell death. Concentrations of cefazolin of 100 microg/ml and less have little or no effect on osteoblast replication, 200 microg/ml significantly decrease cell replication, and 10,000 microg/ml cause cell death. The authors conclude that vancomycin is less toxic than is cefazolin to osteoblasts at higher concentrations and may be a better antibiotic for local administration in the treatment of similarly sensitive bacterial infections.

Autogeneic canceUous bone graft has been recommended as a vehicle for local antibiotic delivery. Its effect on graft incorporation, however, is unknown. The healing of defects grafted with tobramycin-impregnated cancellous bone were compared with those grafted with cancellous bone alone. Plane roentgenographs, microradiographs, bone density analyses, histologic examination, and biomechanical testing were performed on specimens throughout the course of healing. The presence of large concentrations of local tobramycin does not appear to affect the normal healing characteristics of cancellous bone graft

Summary In October 2013, the International Combined Orthopaedic Research Societies (ICORS; http://i-cors.org ) was founded with inaugural member organisations from the previous Combined Orthopaedic Research Society, which had sponsored combined meetings for more than 2 decades. The ICORS is dedicated to the stimulation of orthopaedic and musculoskeletal research in fields such as biomedical engineering, biology, chemistry, and veterinary and human clinical research. The ICORS seeks to facilitate communication with member organisations to enhance international research collaborations and to promote the development of new international orthopaedic and musculoskeletal research organisations. Through new categories of membership, the ICORS represents the broadest coalition of orthopaedic research organisations globally.

This study evaluated the anatomic relationship between the femur and the vessels that arise from the deep femoral artery, that is, the perforating arteries and the nutrient artery. Blue silicone dye was injected through the common femoral artery in 20 fresh human cadavers. An anteromedial and a posterolateral dissection were performed to identify the femoral perforating arteries and the nutrient artery of the femur. The length of the femur and the distances between the tip of the greater trochanter and the perforating arteries and nutrient artery were measured. This study showed that a reliable, clinically applicable topographic relationship exists between the femur and the perforating arteries and the nutrient artery.

The use of unicortical screws instead of bicortical screws in the extreme outer holes of dynamic compression plates (DCPs) has been recommended to minimize the stress riser effect at the end of the plates. The authors examined in vitro two groups of paired canine femurs after compression plates had been applied to the anterolateral diaphyseal surface bilaterally. Group I: intact paired femurs with bicortical peripheral screws in one DCP and unicortical peripheral screws in the other; Group II: osteotomized paired femurs again comparing unicortical and bicortical peripheral DCP screws. All specimens were torsion tested to failure and the torque, stiffness, energy, rotation, and failure fracture length were calculated. Unicortical screws did not enhance the torsional strength in either group, and significantly compromised stiffness, energy, and rotation in the osteotomized group. The only apparent benefit of unicortical peripheral screws in a DCP was a shorter, less comminuted fracture upon failure.