Differences in metal ion release following cobalt-chromium and oxidized zirconium total knee arthroplasty

Ions are released from all metals after implantation in the body through processes of corrosive and mechanical wear. The aim of this study was to investigate whether serum metal ion levels are raised in patients following total knee arthroplasty. Serum levels of chromium, cobalt, aluminium, molybdenum and zirconium were measured in two groups of patients at a minimum of 3 years after knee arthroplasty. Twenty three patients had a cobalt-chromium femoral component and 14 patients had an oxidized zirconium femoral component, acting as a control group as this femoral component is free from cobalt and chromium. All patients had the same titanium tibial base plates, and no patellae were resurfaced. Despite the lack of cobalt and chromium in the prostheses used in the control group, no statistically significant differences in serum cobalt and chromium ion levels were found between the groups. On the basis of these results there does not appear to be any significant rise in serum metal ion levels following total knee arthroplasty several years after implantation.     

Use of oxidized zirconium hemiarthroplasty in hip fractures: clinical results and spectrum analysis

Oxidized zirconium may have improved wear characteristics against polyethylene, but its performance against native cartilage is unknown. Between 1996 and 1998, 52 patients received an oxidized zirconium hemiarthroplasty for the treatment of a hip fracture. Twelve patients (23%) died within 1 year of surgery, and 24 (46%) were surviving at 5 years. In 38 patients with minimum 2-years follow-up, clinical evaluation after surgery averaged 4.5 years with Harris hip scores averaging 78 (range, 55-92). Three patients radiographically showed acetabular protrusion or significant wear, with 2 undergoing revision surgery. An explanted prosthesis demonstrated no appreciable damage by spectrum analysis. Because of the high mortality rate after hip fracture, the clinical benefits of oxidized zirconium hemiarthroplasty in this population, if existent, are difficult to appreciate and currently show no benefits over standard prostheses.     

Mid-term survivorship and clinical outcomes of cobalt-chrome and oxidized zirconium on highly crosslinked polyethylene

BackgroundThe choice of bearing articulation for total hip arthroplasty in younger patients is amenable to debate. We compared mid-term patient-reported outcomes and survivorship across 2 different bearing articulations in a young patient cohort.MethodsWe reviewed patients with cobalt-chrome or oxidized zirconium on highly crosslinked polyethylene who were followed prospectively between 2004 and 2012. Kaplan–Meier analysis was used to determine predicted cumulative survivorship at 5 years with all-cause and aseptic revisions as the outcome. We compared patient-reported outcomes, including the Harris hip score (HHS), Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and Short-form 12 (SF-12) scores.ResultsA total of 622 patients were followed during the study period. Mean follow-up was 8.2 (range 2.0–10.6) years for cobalt-chrome and 7.8 (range 2.1–10.7) years for oxidized zirconium. Mean age was 54.9 ± 10.6 years for cobalt-chrome and 54.8 ± 10.7 years for oxidized zirconium. Implant survivorship was 96.0% (95% confidence interval [CI] 94.9%–97.1%) for cobalt-chrome and 98.7% (95% CI 98.0%–99.4%) for oxidized zirconium on highly crosslinked polyethylene for all-cause revisions, and 97.2% (95% CI 96.2%–98.2%) for cobalt-chrome and 99.0% (95% CI 98.4%–99.6%) for oxidized zirconium for aseptic revisions. An age-, sex- and diagnosis-matched comparison of the HHS, WOMAC and SF-12 scores demonstrated no significant changes in clinical outcomes across the groups.ConclusionBoth bearing surface couples demonstrated excellent mid-term survivorship and outcomes in young patient cohorts. Future analyses on wear and costs are warranted to elicit differences between the groups at long-term follow-up.     

Surface oxidized zirconium total hip arthroplasty head damage due to closed reduction effects on polyethylene wear

Recent case studies of surface oxidized zirconium THA heads removed after attempted, closed reduction have shown significant surface damage that has been suggested as potentially deleterious to polyethylene wear. We obtained 4 clinically retrieved specimens, produced well-characterized surface damage on additional heads, and tested them on a hip simulator. After 1 million cycles, the amount of polyethylene wear was related to the extent of surface damage, the most damaged clinical specimen showing more than 50 times more wear than a new head. Although all heads after failed attempted closed reduction(s) should be replaced, surface oxidized zirconium heads are of particular concern; those patients with a successful, simple closed reduction should be monitored for excessive wear.     

Clinical applications of BMPs

Bone morphogenetic proteins (BMPs) are polypeptides discovered by Marshall Urist in 1965 and later defined by his co-workers as multifunctional cytokines involved in osteoinduction. They are members of the transforming growth factor-beta superfamily with the exception of the BMP-1. Till now at least 20 BMPs have been identified and studied, but only BMP 2, 4 and 7 have been able in vitro to stimulate the entire process of stem cell differentiation into osteoblastic mature cells. After in vitro studies BMPs have been tested in preclinical and clinical studies, showing their definite potential in osteoinduction and have been approved for clinical use in open fracture of long bones, non-unions and vertebral arthrodesis. But more clinical use of these molecules is under investigation and the possibility of using gene therapy in selected pathologies seems the most appealing.     

Wear of polyethylene against oxidized zirconium femoral components effect of aggressive kinematic conditions and malalignment in total knee arthroplasty

Metallic femoral components with ceramic articulating surfaces can substantially lower polyethylene (PE) wear during walking activities under conditions of normal knee alignment. It is unknown whether these types of components can maintain low wear rates under conditions of knee malalignment and the harsher kinematics associated with younger, athletically active patients. Wear was measured in non-cross-linked, ethylene oxide-sterilized PE inserts against oxidized zirconium or cobalt-chrome femoral components in a knee wear simulator. The vertical load was modified to replicate knee varus malalignment of 3°, and the range of tibial rotation was increased to 20°. Mean gravimetric and volumetric wear rate over 5 million cycles was 55% lower in the oxidized zirconium group. An oxidized zirconium femoral component can significantly reduce PE wear under simulated conditions of athletically active patients with modestly malaligned total knee arthroplasty prostheses.     

Clinical applications of mechanical ventilation

This paper reviews recent applications of mechanical ventilation such as controlled hypoventilation in acute asthma, domiciliary nocturnal ventilation in chronic respiratory failure due to neuromuscular disease and improvement of left ventricular performance by raised intrathoracic pressure. Established uses of mechanical ventilation include control of respiratory failure, intracranial pressure and pulmonary hypertension while other uses such as internal splinting of flail chest, simultaneous ventilation-compression cardiopulmonary resuscitation and prophylactic postoperative ventilation are more controversial.     

骨盆参数及其临床意义

骨盆形态对人体矢状面平衡起着至关重要的作用。骨盆参数是站立位躯干全长侧位X线片上反映骨盆形态的相关参数,分为解剖参数和姿势相关性参数两类。脊柱矢状面形态与骨盆参数密切相关,脊柱矢状面曲线分型也采用骨盆参数。相关临床研究显示,脊柱滑脱、脊柱畸形、腰椎退行性疾病病人的骨盆参数均有不同程度的特征性变化。骨盆参数在腰椎生理曲度重建中的应用日益受到关注。     

Clinical applications of stereotaxic methology

Cerebral stereotaxy is an old methodology allowing an accurate approach of a lesion or a function, in constant renewal with the introduction of computers and robotic. There is a natural complementarity with recent neuroradiological investigations and together, it is possible to reach cerebral deep-seated or functional structures with inocuity and fiability for diagnosis and/or therapy. Its application is very large and also influences neuronavigation procedures, current in conventional neurosurgery. Tumoral stereotaxy is commonly used and achieves a better adaptation of the therapeutical strategy according to the lesions' site and histological diagnosis. The development of functional stereotaxy is associated with the interest of the neurosurgical treatment of involuntary abnormal movements, without forgetting different aspects of surgery of chronic pain and intractable epilepsies. Moreover, the stereotactic methodology leads the concept of radiosurgery, which is in some indications a true alternative to open surgery (arteriovenous malformations, vestibular schwannoma, metastasis) under the control of accurate selection in a multidisciplinary approach.     

Clinical applications of induced hypothermia

The first 150 words of the full text of this article appear below. Key points Induced hypothermia aims to avoid the complicationsassociated with hypothermia. It is principally used in comatosecardiac arrest survivors, head injury, and neonatal encephalopathy. Themechanism of action is thought to be mediated by preventionof cerebral reperfusion injury. The main problems associatedwith its use are diuresis, electrolyte imbalance and immunosuppression. TheInternational Liaison Committee on Resuscitation recommend thatit is used for comatose survivors of VF, out-of-hospital cardiacarrests. Cerebral hypothermia can safely improve intact survivalin term infants with neonatal encephalopathy.   Hypothermia is a well known cause of death, particularly incolder climates; however, it may also be used to preserve life.Defined as a core temperature <35°C, hypothermia as atreatment for medical conditions is not a new practice. AncientGreek physicians used hypothermia for various conditions includinghaemorrhage and trauma. More recent use has centred on its efficacyas a neuroprotective strategy. Therapeutic . . . [Full Text of this Article]