Age-related differences in hamstring tendon used as autograft in reconstructive anterior cruciate ligament surgery.

PURPOSE: The hamstring tendon is the most commonly used autograft material in reconstructive surgeries of anterior cruciate ligament (ACL) tears. Younger patients have worse surgical outcomes, with a higher risk of re-rupture. We hypothesized that age-related changes in hamstring tendon properties affect the tendon's propensity to rupture when used as an autograft in ACL reconstructions. The purpose of this study was to compare hamstring tendon samples obtained from people aged 20 years or younger to samples obtained from older people. METHODS: Superfluous hamstring tendon material was collected from 13 young donors (aged 16-20 years) and 17 older donors undergoing ACL reconstructive surgery. Sections of the tendon samples were used for biomechanical testing, structural analysis of collagen fibrils by electron microscopy, and global analysis of gene expression by microarrays. RESULTS: We found that tendon samples from the older group had lower Young's modulus than the younger group (P = 0.015), whereas the stress to failure was similar in the two groups. We found no difference in the average diameter of collagen fibrils between the two groups. Microarray analysis identified 162 differentially expressed genes (fold change ≥ 1.5, P < 0.05), with overrepresentation of several biological processes, including regulation of adhesion, migration, inflammation, and differentiation (fold enrichment > 2.0, false discovery rate P < 0.05). CONCLUSION: The hamstring tendon from younger people has higher stiffness than tendon from older people, and the profile of gene expression in tendon varies with age. These differences may negatively affect the performance of the hamstring tendon in ACL reconstructions in younger people.

Vascular Injuries During Hip and Knee Replacement.

Vascular injuries associated with hip and knee arthroplasty are rare but can result in devastating outcomes for the patient. A sound knowledge of vascular anatomy, potential mechanisms of injury, and diagnosis and management of vascular injuries are vital to an arthroplasty surgeon. Identifying high-risk patients and procedures allows careful preoperative planning, which combined with meticulous intraoperative technique, may help avoid vascular complications. When vascular injuries do occur, early recognition and intervention are critical to an improved outcome.

Characterization of Parylene-C degradation mechanisms: In vitro reactive accelerated aging model compared to multiyear in vivo implantation.

Implantable neural microelectrodes are integral components of neuroprosthetic technologies and can transform treatments for many neural-mediated disorders. However, dielectric material degradation during long-term (>1 year) indwelling periods restricts device functional lifetimes to a few years. This comprehensive work carefully investigates in vivo material degradation and also explores the ability of in vitro Reactive Accelerated Aging (RAA) to evaluate implant stability. Parylene C-coated Utah electrode arrays (UEAs) implanted in feline peripheral nerve for 3.25 years were explanted and compared to RAA-processed devices, aged in phosphate buffered saline (PBS) + 20 mM H2O2 at either 67 or 87 °C (28 or 7 days, respectively). Electron microscopy revealed similar physical damage characteristics between explants and RAA (87 °C) devices. Parylene C degradation was overwhelmingly apparent for UEAs from both RAA cohorts. Controls aged in PBS alone displayed almost no damage. Spectroscopic characterization (EDX, XPS, FTIR) found clear indications of oxidation and chlorine abstraction for Parylene C aged in vivo. While in vitro aging was also accompanied by signs of oxidation, changes in the chemistry in vivo and in vitro were statistically different. Analysis of RAA-aged devices identified UEA fabrication approaches that may greatly improve device resistance to degradation. This work underscores the need for an improved understanding of in vivo damage mechanisms, to facilitate the critical need for representative in vitro accelerated testing paradigms for long-term implants.

Automated reactive accelerated aging for rapid in vitro evaluation of neural implant performance.

Novel therapeutic applications for neural implants require miniaturized devices. Miniaturization imposes stricter requirements for reliability of materials. Pilot clinical studies suggest that rapid failure of the miniaturized neural implants in the body presents a major challenge for this type of technology. Traditional evaluations of neural implant performance over clinically relevant durations present time- and resource-intensive experiments in animals. Reactive accelerated aging (RAA) is an in vitro test platform that was developed to expedite durability testing of neural implants, as a screening technique designed to simulate the aggressive physiological environment experienced by the implants. This approach employs hydrogen peroxide, which mimics reactive oxygen species, and a high temperature to accelerate chemical reactions that lead to device degradation similar to that found with devices implanted in vivo. The original RAA system required daily manual maintenance and was prone to variability in performance. To address these limitations, this work introduces automated reactive accelerated aging (aRAA) with closed-loop monitoring components that make the system simple, robust, and scalable. The core novel technology in the aRAA is electrochemical detection for feedback control of hydrogen peroxide concentration, implemented with simple off-the-shelf components. The aRAA can run multiple parallel experiments for high-throughput device testing and optimization. For this reason, the aRAA provides a simple tool for rapid in vitro evaluation of the durability of neural implants, ultimately expediting the development of a new generation of miniaturized devices with a long functional lifespan.

Neural electrode resilience against dielectric damage may be improved by use of highly doped silicon as a conductive material.

BACKGROUND: Dielectric damage occurring in vivo to neural electrodes, leading to conductive material exposure and impedance reduction over time, limits the functional lifetime and clinical viability of neuroprosthetics. We used silicon micromachined Utah Electrode Arrays (UEAs) with iridium oxide (IrOx) tip metallization and parylene C dielectric encapsulation to understand the factors affecting device resilience and drive improvements. NEW METHOD: In vitro impedance measurements and finite element analyses were conducted to evaluate how exposed surface area of silicon and IrOx affect UEA properties. Through an aggressive in vitro reactive accelerated aging (RAA) protocol, in vivo parylene degradation was simulated on UEAs to explore agreement with our models. Electrochemical properties of silicon and other common electrode materials were compared to help inform material choice in future neural electrode designs. RESULTS: Exposure of silicon on UEAs was found to primarily affect impedance at frequencies >1kHz, while characteristics at 1 kHz and below were largely unchanged. Post-RAA impedance reduction of UEAs was mitigated in cases where dielectric damage was more likely to expose silicon instead of IrOx. Silicon was found to have a per-area electrochemical impedance >10×higher than many common electrode materials regardless of doping level and resistivity, making it best suited for use as a low-shunting conductor. COMPARISON WITH EXISTING METHODS: Non-semiconductor electrode materials commonly used in neural electrode design are more susceptible to shunting neural interface signals through dielectric defects, compared to highly doped silicon. CONCLUSION: Strategic use of silicon and similar materials may increase neural electrode robustness against encapsulation failures.

Human Spinal Bone Dust as a Potential Local Autograft: In Vitro Potent Anabolic Effect on Human Osteoblasts.

STUDY DESIGN: In vitro Study. OBJECTIVE: To evaluate the effect that factors released from human posterior spinal bone dust have on primary human osteoblast growth and maturation. SUMMARY OF BACKGROUND DATA: Bone dust, created during spinal fusion surgeries, has the potential to be used as an autologous bone graft by providing a source of viable autologous osteoblasts and mesenchymal stem cells with osteogenic potential. Till date, no information is available on whether bone dust also provides a source of anabolic factors with the potential to enhance osteoblast proliferation and maturation, which would enhance its therapeutic potential. METHODS: Bone dust was collected from consenting patients undergoing elective posterior spinal fusion surgeries, and primary human osteoblasts were cultured from patients undergoing elective hip or knee arthroplasty. Growth factors and cytokines released by bone dust were quantified using enzyme-linked immunosorbent assay. Primary human osteoblast proliferation and gene expression in response to bone dust were assessed using H-thymidine incorporation and real-time polymerase chain reaction, respectively. RESULTS: Human bone dust released anabolic cytokines (IL-1ß and IL-6) and growth factors (TGF-ß, VEGF, FGF-Basic, and PDGF-BB) in increasing concentrations over a 7-day period. In vitro, the anabolic factors released by bone dust increased osteoblast proliferation by 7-fold, compared with osteoblasts cultured alone. In addition, the factors released from bone dust up-regulated a number of osteoblastic genes integral to osteoblast differentiation, maturation, and angiogenesis. CONCLUSION: This study is the first to demonstrate that human posterior spinal bone dust released anabolic factors that potently enhance osteoblast proliferation and the expression of genes that favor bone healing and bone union. As bone dust is anabolic and its harvest is fast, simple, and safe to perform, spinal surgeons should be encouraged to 'recycle' bone dust and harness the regenerative potential of this free autologous bone graft. LEVEL OF EVIDENCE: N/A.

The Efficacy of Local Autologous Bone Dust: A Systematic Review.

STUDY DESIGN: A systematic review of bone dust as an autologous bone graft to encourage osseous fusion. OBJECTIVE: To identify and review studies that report on the therapeutic potential of bone dust. The research question was structured as follows: populations-animal and human sources of bone dust harvested using burrs; interventions-autologous bone dust compared with other clinically utilized bone graft options; outcomes assessed-(1) in vitro cell viability, cell differentiation, and osteogenic potential and (2) clinical efficacy in the form of fusion rates as assessed using plain radiographs; study designs-in vitro, preclinical in vivo and clinical studies investigating the therapeutic potential of bone dust, harvested by burring, are included in this systematic review. SUMMARY OF BACKGROUND DATA: Little is known about the efficacy of bone dust, generated during burring of local bone in spine surgery, as a bone graft to encourage osseous union. METHODS: A systematic search was conducted in Medline, PubMed, OVID, Scopus, and Cochrane library. The following key words were used: bone dust, bone burring, bone paste, bone pate. RESULTS: A total of 285 studies were reviewed. Fourteen articles were identified as relevant for inclusion in this systematic review. Current evidence suggests that bone dust retains osteogenic properties, but limited information is available regarding the osteoinductive potential of bone dust. CONCLUSION: Bone dust represents a free source of autologous bone, which can be easily collected during the time of surgery and used as an augment to aid osseous fusion. Further research is required to evaluate the osteoinductive potential of bone dust. The retained growth factors in bone dust may potentially induce local osteoprogenitor cells to proliferate and mineralize to form new bone.

Mortality following snake bite envenomation by Bitis arietans in an HIV positive child: A case report.

Snake bites occur commonly in the rural areas of South Africa. Hospitals where snake bites are uncommon should always have protocols on standby in the event of such cases presenting. This is the first reported case documenting the effect of human immunodeficiency virus (HIV) on snake bite in South African children.A case report and review of relevant information about the case was undertaken.We present a case of a 1-year-old child referred from a peripheral hospital following a snake bite to the left upper limb with a compartment syndrome and features of cytotoxic envenomation. The patient presented late with a wide area of necrotic skin on the arm requiring extensive debridement. The underlying muscle was not necrotic. Polyvalent antivenom (South African Institute of Medical Research Polyvalent Snakebite Antiserum) administration was delayed by 4 days after the snake bite. The patient was also diagnosed with HIV and a persistent thrombocytopenia possibly due to both HIV infection and the snake bite venom. Lower respiratory tract infections with subsequent overwhelming sepsis ultimately resulted in the child's death.The case highlights the challenge of treating a snake bite in a young child with HIV and the detrimental outcome of delayed treatment. A protocol is essential in the management of snake bites in all hospitals.Level IV, Case report.This case highlights the interaction of snake bite envenomation and HIV infection on thrombocytopenia.

Pediatric Tibial Osteomyelitis.

BACKGROUND: Osteomyelitis shows a strong predilection for the tibia in the pediatric population and is a significant source of complications. The purpose of this article is to retrospectively review a large series of pediatric patients with tibial osteomyelitis. We compare our experience with that in the literature to determine any factors that may aid diagnosis and/or improve treatment outcomes. METHODS: A 10-year retrospective review was performed of clinical records of all cases of pediatric tibial osteomyelitis managed at the 2 children's orthopaedic departments in the Auckland region. The Osteomyelitis Database was used to identify all cases between 1997 and 2007, at Starship Children's Hospital, and 1998 and 2008 at Middlemore's Kids First Hospital. RESULTS: One hundred ninety-one patients fulfilled the inclusion criteria, and had a review of clinical notes and relevant investigations. The average duration of symptoms before presentation to hospital was 5.7 days. Less than 40% of patients had a recent episode of trauma. Almost 60% of patients could not bear weight on admission. Over 40% of patients had a temperature above 38°C. Erythrocyte sedimentation rate was elevated in 78% and the C-reactive protein was elevated in 90% of patients. In total, 42% of blood cultures and almost 75% of tissue cultures were positive, with Staphylococcus aureus being the most commonly cultured organism. X-rays, bone scans, and magnetic resonance imaging were all used to aid the diagnosis. About 43% of patients had surgery. Treatment length was an average of 2 weeks 6 days of intravenous antibiotics followed by 3 weeks 2 days of oral treatment. Six postsurgical complications and 46 readmissions were noted: 25 for relapse, with the remainder due to social and antibiotic-associated complications. CONCLUSIONS: Although generally diagnosed on presentation, pediatric tibial osteomyelitis can require more sophisticated investigations and prolonged management. Treatment with intravenous and oral antibiotics and surgical debridement where indicated can lead to a good clinical outcome, although complications are often noted. LEVEL OF EVIDENCE: Level IV-Prognostic study.

Augmentation with an ovine forestomach matrix scaffold improves histological outcomes of rotator cuff repair in a rat model.

BACKGROUND: Rotator cuff tears can cause significant pain and functional impairment. Without surgical repair, the rotator cuff has little healing potential, and following surgical repair, they are highly prone to re-rupture. Augmenting such repairs with a biomaterial scaffold has been suggested as a potential solution. Extracellular matrix (ECM)-based scaffolds are the most commonly used rotator cuff augments, although to date, reports on their success are variable. Here, we utilize pre-clinical in vitro and in vivo assays to assess the efficacy of a novel biomaterial scaffold, ovine forestomach extracellular matrix (OFM), in augmenting rotator cuff repair. METHODS: OFM was assessed in vitro for primary tenocyte growth and adherence, and for immunogenicity using an assay of primary human dendritic cell activation. In vivo, using a murine model, supraspinatus tendon repairs were carried out in 34 animals. Augmentation with OFM was compared to sham surgery and unaugmented control. At 6- and 12-week time points, the repairs were analysed biomechanically for strength of repair and histologically for quality of healing. RESULTS: OFM supported tenocyte growth in vitro and did not cause an immunogenic response. Augmentation with OFM improved the quality of healing of the repaired tendon, with no evidence of excessive inflammatory response. However, there was no biomechanical advantage of augmentation. CONCLUSIONS: The ideal rotator cuff tendon augment has not yet been identified or clinically implemented. ECM scaffolds offer a promising solution to a difficult clinical problem. Here, we have shown improved histological healing with OFM augmentation. Identifying materials that offset the poorer mechanical properties of the rotator cuff post-injury/repair and enhance organised tendon healing will be paramount to incorporating augmentation into surgical treatment of the rotator cuff.

Pediatric Acute Hematogenous Osteomyelitis.

BACKGROUND: Osteomyelitis continues to be a significant problem among the New Zealand pediatric population. We present a large series of acute hematogenous osteomyelitis (AHO) cases, with the aim to identify any changing trends and guide successful management of the disease. METHODS: A 10-year retrospective review was performed of clinical records of children with AHO at the 2 children's orthopaedic departments in the Auckland region. Cases were identified from Starship Children's Hospital between 1997 and 2007 and Middlemore's Kidz First Hospital between 1998 and 2008. RESULTS: A total of 813 cases of pediatric AHO were identified. The incidence was 1:4000, which was decreasing over the 10-year period. There was a male predominance and New Zealand (NZ) Maori and Pacific Islanders were overrepresented. The diagnosis was made clinically in 27%, radiographically in 66%, and surgically in 7%. The most common pathogen was Staphylococcus aureus and the incidence of methicillin-resistant S. aureus was low (2%). The average length of antibiotic treatment was 44 days and 44% required surgery. This produced a recurrence rate of only 7% and a 15% treatment-related complication rate. CONCLUSIONS: In the New Zealand population, the incidence of AHO remains high with NZ Maori and Pacific Islanders overrepresented. The predominant pathogen remains S. aureus and our population has a very low incidence of methicillin-resistant S. aureus; flucloxacillin remains a good choice for empiric treatment in our population. Our rate of relapse and subsequent chronic osteomyelitis is low. This could be explained by traditionally longer antibiotic courses; however, this may also lead to increased treatment-related complications. Through prompt and accurate diagnosis with the aid of laboratory and radiologic tests and effective treatment with appropriate antibiotics (guided by local pathogen sensitivities) and surgical treatment when indicated, AHO can be well managed with minimal severe complications. LEVEL OF EVIDENCE: Level IV-retrospective case series.

Pediatric Humeral Osteomyelitis.

BACKGROUND: Osteomyelitis is a common problem among the pediatric population. The humerus is the most commonly affected bone in the upper limb; however, there are relatively few series in the literature. This article retrospectively reviews a large number of cases of pediatric humeral osteomyelitis. We aim to further define the disease and its clinical course to aid in improved treatment. METHODS: A 10-year retrospective review was performed of clinical records of pediatric humeral osteomyelitis at the 2 children's orthopaedic departments in the Auckland region. The Osteomyelitis Database was used to identify all cases between 1997 and 2007 at Starship Children's Hospital, and 1998 and 2008 at Middlemore's Kidz First Hospital. RESULTS: Forty-nine patients were identified. Sixty-one percent were male with an average age of 4.2 years. Maori and Pacific Islanders were overrepresented. Seventy-eight percent were not using the limb, 70% complained of pain. Only 55% were febrile. White cell count, erythrocyte sedimentation rate, and C-reactive protein raised in 73%, 74%, and 79% of cases, respectively. X-ray, bone scintigraphy, and particularly magnetic resonance imaging were useful in radiologic diagnosis. Blood and tissue cultures revealed Staphylococcus aureus as the most common organism; there were 2 cases of community-acquired methicillin-resistant S. aureus. The distal humerus was more commonly affected. Fifty-three percent required surgery. Antibiotic therapy averaged 2.7 weeks intravenous and 2.6 weeks of oral therapy. There were 7 cases with adjacent septic arthritis, which had higher inflammatory markers. Major complications included 2 multiorgan failure and 1 growth disturbance. CONCLUSIONS: Humeral osteomyelitis can be diagnosed with an appropriate history, clinical examination, and investigations. One should be aware of concurrent septic arthritis and be prepared to treat this urgently. Those children with septic arthritis were not using the limb and had higher inflammatory markers. Treatment with intravenous and oral antibiotics and surgical debridement/washout if indicated can lead to good clinical outcomes with minimal complications. LEVEL OF EVIDENCE: Level IV-retrospective case series.

Pediatric calcaneal osteomyelitis.

BACKGROUND: Osteomyelitis continues to be a common problem amongst the pediatric population. Osteomyelitis of the calcaneus is an uncommon problem that still poses a problem to the treating physician. The purpose of this article is to retrospectively review a large series of pediatric patients with calcaneal osteomyelitis. We compare our experience with that in the literature to determine any factors that may aid earlier diagnosis and or improve treatment outcomes. METHODS: A 10-year retrospective review was performed of clinical records of all cases of pediatric calcaneal osteomyelitis managed at the 2 children's orthopaedic departments in the Auckland region. The Osteomyelitis Database was used to identify all cases between 1997 and 2007, at Starship Children's Hospital, and 1998 and 2008 at Middlemore's Kids First Hospital. RESULTS: Sixty patients fulfilled the inclusion criteria, and had a review of clinical notes and relevant investigations. The average duration of symptoms before presentation to hospital was 6.8 days. About 40% of patients had a recent episode of trauma. About 82% of patients could not bear weight on admission. Only 22% of patients had a temperature above 38°C. Erythrocyte sedimentation rate was elevated in 81% and the C-reactive protein was elevated in 77% of patients. About 27% of patients had positive blood cultures with Staphylococcus aureus being the most commonly cultured organism. X-rays, bone scans, and magnetic resonance imaging were all used to aid the diagnosis. About 20% of patients had surgery with an average of 1.3 surgeries for those who progressed to surgery. Treatment length was an average of 2 weeks 6 days of intravenous antibiotics followed by 3 weeks 2 days of oral treatment. There were no postsurgical complications and 10 readmissions: 3 for relapse, 3 for peripherally inserted central catheter line problems, and 4 for antibiotic-associated complications. CONCLUSIONS: Although sometimes more difficult to diagnose, calcaneal osteomyelitis can be diagnosed with an appropriate history, clinical examination, and investigations. Treatment with intravenous and oral antibiotics and surgical debridement if indicated can lead to a good clinical outcome with minimal complications.