Cobalt toxicity in humans—a review of the potential sources and systemic health effects

The first edition (1981) of this comprehensive work weighed 25 lb and had 3300 pages. This entirely new third edition, published 14 years later, has grown to 45 lb and 4850 pages. This growth is not due to inflation but is the direct result of the information explosion. The multiplication of techniques for imaging and studying the bone and soft tissues has made choosing the best method for examination of the patient more difficult and, in an environment in which cost-effectiveness has become a byword, more important. An underlying principle of this work is to guide the physician in the choice of the technology to be employed to get essential information quickly and efficiently. Dr Resnick has called on a group of 40 contributors for special information, but he himself has played a major role in the writing and has been more than an editor, thereby ensuring a consistent and

Diagnosis of Bone and Joint Disorders

Background Despite the excellent outcomes associated with primary total hip arthroplasty (THA), implant failure and revision continues to burden the healthcare system. THA failure has evolved and displays variability throughout the literature. In order to understand how THAs are failing and how to reduce this burden, it is essential to assess modes of implant failure on a large scale. Thus, we report: (1) etiologies for revision THA; (2) frequencies of revision THA procedures; (3) patient demographics, payor type, and US Census region of revision THA patients; and (4) the length of stay and total costs based on the type of revision THA procedure. Methods We queried the National Inpatient Sample database for all revision THA procedures performed between January 1, 2009 and December 31, 2013. This yielded 258,461 revision THAs. Patients specific demographics were identified in order to determine the prevalence of revision procedure performed. Results Dislocation was the main indication for revision THA (17.3%), followed by mechanical loosening (16.8%). All-component revision was the most common procedure performed (41.8%). Patients were most commonly white (77.4%), aged 75 years and older (31.6%), and resided in the South US Census region (37.0%). The average length of stay for all procedures was 5.29 days. The mean total charge for revision THA procedures was $77,851.24. Conclusion Dislocation and mechanical loosening is the predominant indication for revision THA in the United States. With the frequency of revision THAs projected to double in the next decade, orthopedists must take steps to mitigate this potentially devastating complication.

Current Epidemiology of Revision Total Hip Arthroplasty in the United States: National Inpatient Sample 2009 to 2013

It is estimated that 20000 to 30000 new patients are diagnosed with osteonecrosis annually accounting for approximately 10% of the 250000 total hip arthroplasties done annually in the United States. The lack of level 1 evidence in the literature makes it difficult to identify optimal treatment protocols to manage patients with pre-collapse avascular necrosis of the femoral head, and early intervention prior to collapse is critical to successful outcomes in joint preserving procedures. There have been a variety of traumatic and atraumatic factors that have been identified as risk factors for osteonecrosis, but the etiology and pathogenesis still remains unclear. Current osteonecrosis diagnosis is dependent upon plain anteroposterior and frog-leg lateral radiographs of the hip, followed by magnetic resonance imaging (MRI). Generally, the first radiographic changes seen by radiograph will be cystic and sclerotic changes in the femoral head. Although the diagnosis may be made by radiograph, plain radiographs are generally insufficient for early diagnosis, therefore MRI is considered the most accurate benchmark. Treatment options include pharmacologic agents such as bisphosphonates and statins, biophysical treatments, as well as joint-preserving and joint-replacing surgeries. the surgical treatment of osteonecrosis of the femoral head can be divided into two major branches: femoral head sparing procedures (FHSP) and femoral head replacement procedures (FHRP). In general, FHSP are indicated at pre-collapse stages with minimal symptoms whereas FHRP are preferred at post-collapse symptomatic stages. It is difficult to know whether any treatment modality changes the natural history of core decompression since the true natural history of core decompression has not been delineated.

Current concepts on osteonecrosis of the femoral head

Robotic-assisted orthopedic surgery has been available clinically in some form for over 2 decades, claiming to improve total joint arthroplasty by enhancing the surgeon's ability to reproduce alignment and therefore better restore normal kinematics. Various current systems include a robotic arm, robotic-guided cutting jigs, and robotic milling systems with a diversity of different navigation strategies using active, semiactive, or passive control systems. Semiactive systems have become dominant, providing a haptic window through which the surgeon is able to consistently prepare an arthroplasty based on preoperative planning. A review of previous designs and clinical studies demonstrate that these robotic systems decrease variability and increase precision, primarily focusing on component positioning and alignment. Some early clinical results indicate decreased revision rates and improved patient satisfaction with robotic-assisted arthroplasty. The future design objectives include precise planning and even further improved consistent intraoperative execution. Despite this cautious optimism, many still wonder whether robotics will ultimately increase cost and operative time without objectively improving outcomes. Over the long term, every industry that has seen robotic technology be introduced, ultimately has shown an increase in production capacity, improved accuracy and precision, and lower cost. A new generation of robotic systems is now being introduced into the arthroplasty arena, and early results with unicompartmental knee arthroplasty and total hip arthroplasty have demonstrated improved accuracy of placement, improved satisfaction, and reduced complications. Further studies are needed to confirm the cost effectiveness of these technologies.

Robotics in Arthroplasty: A Comprehensive Review.

Successful total knee arthroplasty (TKA) has often been based on the restoration of the knee to neutral alignment postoperatively. Numerous reports have linked malaligned TKA components to increased wear, poor functional outcomes, and failure. There have been many different alignment philosophies and surgical techniques that have been established to attain the goal of proper alignment, which includes such techniques as computerized navigation, and custom cutting guides. In addition, these methods could potentially have the added benefit of leading to improved functional outcomes following total knee arthroplasty. In this report, we have reviewed and analyzed recent reports concerning mechanical, anatomic, and kinematic axis/alignment schemes used in total knee arthroplasty.

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Mechanical, Anatomical, and Kinematic Axis in TKA: Concepts and Practical Applications

➤ Short bone-conserving femoral stems in total hip arthroplasty were designed to preserve proximal bone stock.

➤ Given the distinct fixation principles and location of loading among these bone-conserving stems, a classification system is essential to compare clinical outcomes.

➤ Due to the low quality of currently available evidence, only a weak recommendation can be provided for clinical usage of certain stem designs, while some other designs cannot be recommended at this time.

➤ A high prevalence of stem malalignment, incorrect sizing, subsidence, and intraoperative fractures has been reported in a subset of these short stem designs.

➤ Stronger evidence, including prospective multicenter randomized trials comparing standard stems with these newer designs, is necessary before widespread use can be recommended.

Short bone-conserving stems in cementless hip arthroplasty.

Background
Aseptic loosening is the most common cause for revisions after lower-extremity total joint arthroplasties, however studies differ regarding the degree to which host factors influence loosening.

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What Host Factors Affect Aseptic Loosening After THA and TKA

The purpose of this systematic review was to compare the outcomes of static to articulating antibiotic spacers used in two-stage revision total knee arthroplasty. 48 reports with a total of 962 articulating spacers (949 patients) and 707 static spacers (688 patients) with a mean 4 year follow-up were identified for this review. Data on clinical function scores, range-of-motion, complications, and re-infection rates were collected on static and articulating spacers. Both groups had similar improvement in Knee Society Scores (83 versus 82 points), however, the articulating spacer groups had significantly higher range-of-motion (100° versus 92°). There was no difference in the re-infection rates, complication rates, or re-operation rates between the two groups. Currently no specific recommendation can be made about the superiority of one type of spacer over the other.

Systematic review comparing static and articulating spacers used for revision of infected total knee arthroplasty.

The effect of varying corticosteroid regimens on hip osteonecrosis incidence remains unclear. We performed a meta-analysis and systematic literature review to determine osteonecrosis occurrences in patients taking corticosteroids at varying mean and cumulative doses and treatment durations, and whether medical diagnoses affected osteonecrosis incidence. Fifty-seven studies (23,561 patients) were reviewed. Regression analysis determined significance between corticosteroid usage and osteonecrosis incidence. Osteonecrosis incidence was 6.7% with corticosteroid treatment of >2 g (prednisone-equivalent). Systemic lupus erythematosus patients had positive correlations between dose and osteonecrosis incidence. Each 10 mg/d increase was associated with a 3.6% increase in osteonecrosis rate, and >20 mg/d resulted in a higher osteonecrosis incidence. Clinicians must be wary of osteonecrosis in patients on high corticosteroid regimens, particularly in systematic lupus erythematosus.

Samik Banerjee

Papers

Mechanical, Anatomical, and Kinematic Axis in TKA: Concepts and Practical Applications

Short bone-conserving stems in cementless hip arthroplasty.

What Host Factors Affect Aseptic Loosening After THA and TKA

Systematic review comparing static and articulating spacers used for revision of infected total knee arthroplasty.

High-Dose Corticosteroid Use and Risk of Hip Osteonecrosis: Meta-Analysis and Systematic Literature Review.