Clinical and radiologic outcomes of a fully hydroxyapatite-coated femoral revision stem:excessive stress shielding incidence and its consequences

\u3cp\u3eStress shielding remains a concern in total hip arthroplasty. The consequences of stress shielding in hydroxyapatite-coated femoral component revisions were evaluated in a prospective cohort study. A total of 106 patients operated on by revision total hip arthroplasty were identified. Sixty-three patients were eligible for clinical and radiologic assessment of osseointegration, bone remodeling, and stress shielding. Five patients showed evidence of excessive stress shielding. One patient experienced a periprosthetic fracture. No adverse events occurred in the remaining patients with a low rate of thigh pain and reliable osseointegration. This is the only available study concerning mid- to long-term consequences of excessive stress shielding in hydroxyapatite-coated revision stems. We advocate surgeons using these stems to remain vigilant and be aware of possible stress shielding side effects.\u3c/p\u3

Computer-assisted total knee arthroplasty using mini midvastus or medial parapatellar approach technique:a prospective, randomized, international multicentre trial Orthopedics and biomechanics

\u3cp\u3eBackground: Despite the growing evidence in the literature there is still a lack of consensus regarding the use of minimally invasive surgical technique (MIS) in total knee arthroplasty (TKA). Methods: A prospective, randomized, international multicentre trial including 69 patients was performed to compare computer-assisted TKA (CAS-TKA) using either mini-midvastus (MIS group) or standard medial parapatellar approach (conventional group). Patients from 3 centers (Maastricht, Zwickau, Adelaide) with end-stage osteoarthritis of the knee were randomized to either an MIS group with dedicated instrumentation or a conventional group to receive cruciate retaining CAS-TKA without patella resurfacing. The primary outcome was to compare post operative pain and range of motion (ROM). The secondary outcome was to measure the duration of surgery, blood loss, chair rise test, quadriceps strength, anterior knee pain, Knee Society Score (KSS),WOMAC scores, mechanical leg axis and component alignment. Results: Patients in the MIS group (3.97 ± 2.16) had significant more pain at 2 weeks than patients in the conventional group (2.77 ± 1.43) p = 0.003. There was no significant difference in any of the other primary outcome parameters. Surgery time was significantly longer (p < 0.001) and there were significantly higher blood loss (p = 0.002) in the MIS group as compared to the conventional group. The difference of the mean mechanical leg alignment between the groups was not statistically significant (-0.43° (95 % CI -1.50 - 0.64); p = 0.43). There was no significant difference of component alignment between the two surgical groups with respect to flexion/extension (p = 0.269), varus/valgus (p = 0.653) or rotational alignment (p = 0.485) of the femur component and varus valgus alignment (p = 0.778) or posterior slope (p = 0.164) of the tibial component. Conclusion: There was no advantage of the MIS approach compared to a conventional approach CAS-TKA in any of the primary outcome measurements assessed, however the MIS approach was associated with longer surgical time and greater blood loss. MIS-TKA in combination with computer navigation is safe in terms of implant positioning. Trial registration number: ClinicalTrials.gov NCT02625311 8 December 2015.\u3c/p\u3

Experimental models in orthopedic infection research

\u3cp\u3eOsteomyelitis is a devastating disease of the bone tissue and is a severe complication in orthopedic and trauma surgery, especially when combined with prostheses and osteosynthesis. The infection risk of a prosthesis/osteosynthesis is depending on the location of the implant and the health status of the patient. Hip and knee prostheses have an infection risk of up to 4%, while osteosynthesis has a considerable higher infection risk of up to 30%. Considering the increasing number of implants being placed every year and a stable infection rate of these implants, this will result in an increasing prevalence of implant infections. Infection treatment, however, is based on local antibiotic treatment often combined with surgical debridement. In general, a two-stage revision is suggested to be the most effective infection treatment with success rates of up to 93%. Infection prevention, on the other hand, is based on the prevention or delay of bacterial adhesion on the implant surface and to provide a more suitable surface for eukaryotic cells to survive and adhere to it. To study implant infection and to assess novel implant strategies and coatings, experimental animal models are essential. The earliest models date from 1883, which were rather simple in setup. During the last decades, these models became more complex and required less animals. This chapter provides both an overview of experimental models as well as scoring systems to quantify orthopedic infections (ranging from hematological, radiological to histological perspectives). Still there is no ideal model to assess every orthopedic infection; it will always require a dedicated model depending on the research question.\u3c/p\u3

Cost-effectiveness study of one-stage treatment of chronic osteomyelitis with bioactive glass s53p4

\u3cp\u3eThis study was set up to evaluate the costs of a one-stage treatment of chronic osteomyelitis using bioactive glass S53P4 versus a two-stage treatment using gentamicin-loaded PMMA beads. Furthermore, a cost-effectiveness analysis was performed from a hospital's perspective together with the evaluation of clinical outcome. A treatment group (n = 25) receiving one-stage surgery with bioactive glass was retrospectively compared with a two-stage control group (n = 25). An assessment was made of all costs included from first outpatient visit until one year after treatment. Bootstrap simulation and sensitivity analyses were performed. The primary endpoint was cost-effectiveness with clinical outcome as the secondary endpoint. The base case analyses shows dominance of the one-stage treatment with bioactive glass S53P4 due to lower costs and a better clinical outcome. Sensitivity analyses confirm these findings. This study is the first in its kind to show one-stage treatment of chronic osteomyelitis with bioactive glass S53P4 to be cost-effective.\u3c/p\u3

In vitro antimicrobial susceptibility testing methods:agar dilution to 3D tissue-engineered models

\u3cp\u3eIn the field of orthopaedic surgery, bacterial invasion of implants and the resulting periprosthetic infections are a common and unresolved problem. Antimicrobial susceptibility testing methods help to define the optimal treatment and identify antimicrobial resistance. This review discusses proven gold-standard techniques and recently developed models for antimicrobial susceptibility testing, while also providing a future outlook. Conventional, gold-standard methods, such as broth microdilution, are still widely applied in clinical settings. Although recently developed methods based on microfluidics and microdroplets have shown advantages over conventional methods in terms of testing speed, safety and the potential to provide a deeper insight into resistance mechanisms, extensive validation is required to translate this research to clinical practice. Recent optical and mechanical methods are complex and expensive and, therefore, not immediately clinically applicable. Novel osteoblast infection and tissue models best resemble infections in vivo. However, the integration of biomaterials into these models remains challenging and they require a long tissue culture, making their rapid clinical implementation unlikely. A method applicable for both clinical and research environments is difficult to realise. With a continuous increase in antimicrobial resistance, there is an urgent need for methods that analyse recurrent infections to identify the optimal treatment approaches.\u3c/p\u3

A rabbit osteomyelitis model for the longitudinal assessment of early post-operative implant infections

\u3cp\u3eBackground: Implant infection is one of the most severe complications within the field of orthopaedic surgery, associated with an enormous burden for the healthcare system. During the last decades, attempts have been made to lower the incidence of implant-related infections. In the case of cemented prostheses, the use of antibiotic-containing bone cement can be effective. However, in the case of non-cemented prostheses, osteosynthesis and spinal surgery, local antibacterial prophylaxis is not a standard procedure. For the development of implant coatings with antibacterial properties, there is a need for a reliable animal model to evaluate the preventive capacity of such coatings during a specific period of time. Existing animal models generally present a limited follow-up, with a limited number of outcome parameters and relatively large animal numbers in multiple groups.Methods: To represent an early post-operative implant infection, we established an acute tibial intramedullary nail infection model in rabbits by contamination of the tibial nail with 3.8 × 10\u3csup\u3e5\u3c/sup\u3e colony forming units of Staphylococcus aureus. Clinical, haematological and radiological parameters for infection were weekly assessed during a 6-week follow-up with post-mortem bacteriological and histological analyses.Results: S. aureus implant infection was confirmed by the above parameters. A saline control group did not develop osteomyelitis. By combining the clinical, haematological, radiological, bacteriological and histological data collected during the experimental follow-up, we were able to differentiate between the control and the infected condition and assess the severity of the infection at sequential timepoints in a parameter-dependent fashion.Conclusion: We herein present an acute early post-operative rabbit implant infection model which, in contrast to previously published models, combines improved in-time insight into the development of an implant osteomyelitis with a relatively low amount of animals.\u3c/p\u3

S53P4 bioactive glass

Bioactive glasses (BAGs) are synthetic bone graft substitutes that have been investigated by various orthopedic research groups in the past decades. These bone-bonding, osteoconductive materials can be used for various clinical applications. S53P4 is a specific composition of BAG, which is the main topic of this chapter, with the focus on granular S53P4. First, the working mechanism of S53P4 BAG is explained extensively on the basis of surface reactions, the bond to bone, osteostimulation, and bone proliferation around the material. S53P4 BAG has an antibacterial effect that is unique among bone graft materials, which makes the material useful in (suspected) septic bone defects. This antibacterial effect is discussed in detail. Additionally, its degradation and effect on angiogenesis are addressed. The chapter concludes with the current clinical applications of the material that are known in the literature

Reduction of intradiscal pressure by the use of polycarbonate-urethane rods as compared to titanium rods in posterior thoracolumbar spinal fixation

\u3cp\u3eAbstract: Loss of sagittal alignment and balance in adult spinal deformity can cause severe pain, disability and progressive neurological deficit. When conservative treatment has failed, spinal fusion using rigid instrumentation is currently the salvage treatment to stop further curve progression. However, fusion surgery is associated with high revision rates due to instrumentation failure and proximal junctional failure, especially if patients also suffer from osteoporosis. To address these drawbacks, a less rigid rod construct is proposed, which is hypothesized to provide a more gradual transition of force and load distribution over spinal segments in comparison to stiff titanium rods. In this study, the effect of variation in rod stiffness on the intradiscal pressure (IDP) of fixed spinal segments during flexion-compression loading was assessed. An ex vivo multisegment (porcine) flexion-compression spine test comparing rigid titanium rods with more flexible polycarbonate-urethane (PCU) rods was used. An increase in peak IDP was found for both the titanium and PCU instrumentation groups as compared to the uninstrumented controls. The peak IDP for the spines instrumented with the PCU rods was significantly lower in comparison to the titanium instrumentation group. These results demonstrated the differences in mechanical load transfer characteristics between PCU and titanium rod constructs when subjected to flexion-compression loading. The concept of stabilization with a less rigid rod may be an alternative to fusion with rigid instrumentation, with the aim of decreasing mechanical stress on the instrumented segments and the possible benefit of a decrease in the incidence of screw pullout.\u3c/p\u3

The available evidence on demineralised bone matrix in trauma and orthopaedic surgery:a systematic review

\u3cp\u3eObjectives: The aim of this systematic literature review was to assess the clinical level of evidence of commercially available demineralised bone matrix (DBM) products for their use in trauma and orthopaedic related surgery. Methods: A total of 17 DBM products were used as search terms in two available databases: Embase and PubMed according to the Preferred Reporting Items for Systematic Reviews and Meta Analyses statement. All articles that reported the clinical use of a DBM-product in trauma and orthopaedic related surgery were included. Results: The literature search resulted in 823 manuscripts of which 64 manuscripts met the final inclusion criteria. The included manuscripts consisted of four randomised controlled trials (level I), eight cohort studies (level III) and 49 case-series (level IV). No clinical studies were found for ten DBM products, and most DBM products were only used in combination with other grafting materials. DBM products were most extensively investigated in spinal surgery, showing limited level I evidence that supports the use Grafton DBM (Osteotech, Eatontown, New Jersey) as a bone graft extender in posterolateral lumbar fusion surgery. DBM products are not thoroughly investigated in trauma surgery, showing mainly level IV evidence that supports the use of Allomatrix (Wright Medical, London, United Kingdom), DBX (DePuy Synthes, Zuchwil, Switzerland), Grafton DBM, or OrthoBlast (Citagenix Laval, Canada) as bone graft extenders. Conclusions: The clinical level of evidence that supports the use of DBM in trauma and orthopaedic surgery is limited and consists mainly of poor quality and retrospective case-series. More prospective, randomised controlled trials are needed to understand the clinical effect and impact of DBM in trauma and orthopaedic surgery.\u3c/p\u3