Archive | December 2014

“Fat Hormone” Associated with Cartilage Thinning

In a recent Annals of Rheumatic Diseases study, Australian researchers reported that levels of circulating leptin—a hormone that influences body weight and regulates some inflammatory processes—are negatively associated with changes in knee-cartilage thickness.

This prospective cohort study of 163 randomly selected patients (mean age of 63) used MRI to assess knee-cartilage thickness and radioimmunoassay to measure serum leptin levels at baseline and again after an average of 2.7 years. Cross-sectionally, leptin levels were negatively associated with cartilage thickness at femoral, medial tibial, lateral tibial, and patellar sites, after researchers adjusted for age, sex, BMI, and disease status. Longitudinally, baseline levels and changes in leptin over time were associated with greater differences in tibial-cartilage thickness.

The authors speculate that leptin may have a catabolic effect on cartilage that contributes to the development of osteoarthritis (OA), and that decreases in leptin levels associated with weight loss may help explain the clinical improvement in patients with knee OA who lose weight.

JBJS Supplement Cites New Findings from International Device Registries

Surgeons performed more than 1.1 million joint replacements in the US in 2011. That same year, the International Consortium of Orthopaedic Registries (ICOR) was launched to help close gaps in evidence and data collection related to orthopaedic implants. The ICOR network now consists of more than 70 stakeholders and more than 30 orthopaedic registries representing 14 nations.

The December 17, 2014 edition of The Journal contains an online supplement with 14 articles highlighting the achievements of international registries and the findings from 12 ICOR-initiated registry studies. The first article in the supplement (National and International Postmarket Research and Surveillance Implementation) summarizes the findings from the 12 registry studies. The second article (A Distributed Health Data Network Analysis of Survival Outcomes) provides an overview of the data extraction processes and analytic strategies used in the studies.

Key findings from the 12 studies contained in the supplement:

There were no differences in revision risk when metal-on-HXLPE (highly cross-linked polyethylene) implants with larger and smaller femoral head sizes were compared.

Non-cross-linked polyethylene was not associated with significantly worse revision outcomes when compared with metal-on-HXLPE.

Large-head-size metal-on-metal implants were associated with increased risk of revision after two years, compared with metal-on-HXLPE implants.

Use of ceramic-on-ceramic implants with a smaller head size was associated with a higher revision risk compared with metal-on-HXLPE implants and ceramic-on-ceramic implants with head sizes >28 mm.

When compared with hybrid fixation, cementless fixation was associated with an approximately 58% higher risk of revision surgery in patients aged 75 years or older.

Mobile-bearing, non-posterior-stabilized knee designs presented a 40% higher risk of failure than that found with fixed-bearing, non-posterior-stabilized designs.

Compared with fixed-bearing posterior-stabilized knee prostheses, patients who received mobile bearings had an 85% higher chance of revision within the first postoperative year.

Fixed non-posterior-stabilized (cruciate-retainin0 TKA performed better (with or without patellar resurfacing) than did fixed posterior-stabilized (cruciate-substituting) TKA.

Reported revision rates of TKA and THA among pediatric and young-adult patients is currently similar to that for older patients, but the dearth of data makes it incumbent on registries to continue collecting and analyzing data relevant to younger populations.

This systematic review and meta-analysis concluded that surgeons performing a primary THA should use an implant that outperforms benchmarks established by the UK’s National Institute for Health and Care Excellence (NICE).

Among 19 registry reports and 1052 articles examined, only one report and two studies mentioned patient-reported outcome measures (PROMs) and minimum clinically important differences in connection with revision rates after TKA or THA.

Successful collection of PROM data is possible with careful attention to selection of outcome measure(s) and minimizing the data-collection burden on physicians and patients.

Publisher’s Note: Launch of PRE-val supports “Excellence Through Peer Review”

A year ago we debuted the “peer-review statement” in The Journal to emphasize our commitment to pre-publication peer review and to the rigorous, double-blind peer-review process that is integral to our editorial standards.

Today we are happy to announce our participation in PRE-val, the flagship service offered by PRE (Peer Review Evaluation). Our readers will notice the PRE-val badge above the article title for most JBJS articles published on our website in the past 12 months. Clicking on the badge reveals the PRE-val window, which provides detail about the peer review for that particular article. We know that your confidence in the reliability of the information published in The Journal will be increased by the enhanced transparency of our peer-review process.

As a result of the commitment to peer review shared by JBJS and PRE, our Board of Trustees approved the acquisition of PRE in 2014. We are excited about this launch, and we look forward to the implementation of this valuable service on the sites of our partner publishers over the coming months. You can learn more about PRE here. Of course, we welcome your feedback; please let us know what you think of this initiative by writing to us at info@jbjs.org.

Medical publishing continues to evolve-sometimes to keep up with technology, sometimes due to financial constraints, and, unfortunately, sometimes in ways that make some of us uncomfortable-but readers of JBJS can be assured that our commitment to peer review and the quality it helps us to achieve will not waver. “Excellence Through Peer Review” will always remain a critical element of our core mission.

–Mady Tissenbaum, Publisher, JBJS

JBJS Editor’s Choice—Is Hot Air in the OR Risky to Patients?

Forced air warming devices are in widespread use in our orthopaedic surgical suites—and for good reason: Hypothermia can be a major factor in poor patient outcomes due to its negative impact on myocardial function, pharmacokinetics, and other aspects of patient physiology. While maintaining normothermia in surgical patients lowers the risk of postoperative surgical site infections, recent literature has raised concerns about an increased risk of infection in arthroplasty cases in which forced air warming was used.

The December 17, 2014 JBJS literature review by Sikka et al. focuses on this conundrum. It is a well-written summary of current knowledge that clearly outlines the deficiencies in the available data. The authors emphasize that the studies yielding both positive and negative findings are in most cases tainted with detection and selection bias related to industry-funded research designs. This is an area that is begging for a large randomized controlled trial.

However, because of the <1% overall incidence of infection following lower-limb arthroplasty, such a trial will require large numbers of patients. Also essential for such an investigation will be an experienced clinical trialist, meticulous methods, and an apriori definition of “infection.” It is doubtful that registry data analysis can adequately determine the efficacy of forced air warming in preventing major intraoperative adverse events or its impact on postoperative infection, but an analysis of all available data would be a good start.

I look forward to future well-designed studies in this area that will further clarify patient benefit as well as risk. In the meantime, Sikka et al. stress the importance of following all manufacturer instructions for use and maintenance of any patient-warming device.

Marc Swiontkowski, MD

JBJS Editor-in-Chief

JUPITER Says Statins Don’t Deliver Fracture Benefit

When it comes to heart disease and stroke, statins are remarkably effective drugs, and some observational studies have suggested that these lipid-lowering medications might even reduce the risk of bone fractures. But a secondary analysis of the JUPITER trial—a randomized study designed primarily to determine whether rosuvastatin (Crestor) had any effect on cardiovascular outcomes in people who were not candidates for statins—found that statin therapy did not reduce fracture risk. The study population included more than 17,800 men and women with a mean age of 66.

The JUPITER trial was halted after less than two years because of the significant cardiovascular benefits seen in the Crestor group. During that 1.9-year period, 221 imaging-confirmed fractures occurred in the Crestor group, while 210 fractures occurred in the placebo group, according to a paper published online in JAMA Internal Medicine. This fracture-focused secondary analysis was prespecified before the trial started, not run as an afterthought, which adds credibility to the findings.

Online Patient Self-Scheduling Could Save Time and Money

A new report from Accenture estimates that by 2019, two-thirds of US health systems will offer patients the opportunity to digitally self-schedule physician appointments. By reducing the time spent scheduling and rescheduling (an average of 8 minutes per phone appointment versus less than a minute for online self-scheduling), this simple change could save the health care system an estimated $3.2 billion.

Accenture says that nationwide, 11% of health systems currently offer self-scheduling of appointments, but only 2.4% of patients who have the opportunity take advantage of it. That may be partly because retirees—a population that generally prefers conducting business by phone—make up nearly half of the US population. Still, a recent Accenture survey indicated that 77% of patients thought that the ability to book, change, or cancel medical appointments online was important.

What’s New in Orthopaedic Rehabilitation

Every month, JBJS publishes a Specialty Update—a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Here is a summary of key findings from studies cited in the November 19, 2014 Specialty Update on orthopaedic rehabilitation:

General Orthopaedics

  • Among geriatric hip fracture patients, those who received comprehensive postsurgical care (including a multidisciplinary assessment of health, function, and social situation) had significantly more upright time and better Short Physical Performance Battery scores than counterparts who received hospital physiotherapy and conventional care.
  • Seventy-two percent of 51 orthopaedic inpatients exceeded their target goal for prescribed partial weight bearing after being trained. The inability to comply with the training was not associated with poorer outcomes at three months, suggesting clinical support for less-restrictive weight-bearing protocols.
  • A prospective study of 38 unilateral TKA patients revealed that results from squatting exercises more accurately predicted overall functional difficulties than did results from standing with increased weight.
  • A prospective randomized trial among 36 patients who underwent primary ACL reconstruction with semitendinosus-gracilis autograft found no difference in knee laxity, peak isometric force, or subjective IKDC scores between those who had aggressive early rehabilitation versus those undergoing a nonaggressive protocol.

Pediatric Rehabilitation (focused on cerebral palsy patients)

  • Among 100 young children with cerebral palsy, the development of mobility and self-care was faster in children with less severe levels as assessed with the Gross Motor Function Classification System (GMFCS). A separate assessment study supported the validity of the Patient Reported Outcomes Measurement Information System (PROMIS) Mobility Short Form.
  • Results from two gait-analysis studies suggested that using gait analysis in planning interventions for children with cerebral palsy can lead to beneficial alterations in gait.

Amputation and Prosthetics

  • A study comparing functional outcomes after two types of unilateral transtibial amputation (modified Ertl and modified Burgess procedures) found no significant between-group differences.

Spinal Cord Injury

  • A study to assess the safety and efficacy of ReWalk (a lower-limb powered exoskeleton) among 12 patients with motor-complete thoracic spinal cord injury found that all subjects were able to walk independently and continuously for at least 50 to 100 meters. No falls were reported, but a few adverse events related to pressure and irritation occurred.

JBJS Classics: Periprosthetic Bone Loss in Total Hip Arthroplasty

JBJS-Classics-logoEach month during the coming year, OrthoBuzz will bring you a current commentary on a “classic” article from The Journal of Bone & Joint Surgery. These articles have been selected by the Editor-in-Chief and Deputy Editors of The Journal because of their long-standing significance to the orthopaedic community and the many citations they receive in the literature. Our OrthoBuzz commentators will highlight the impact that these JBJS articles have had on the practice of orthopaedics. Please feel free to join the conversation about these classics by clicking on the “Leave a Comment” button in the box to the left.

This classic investigation on periprosthetic bone loss (J Bone Joint Surg Am 1992; 74:849–863) was conducted by Tom Schmalzried in the early 1990s working in William Harris’ laboratory.  Specimens from osteolytic lesions both near and far from the articular surface in 34 total hip arthroplasties were studied by plain and polarized light microscopy, as well as transmission electron microscopy.

The authors emphasized the role of activated macrophages containing micron and submicron polyethylene particles in the bone resorption evident in the areas of osteolysis.  They speculated that the polyethylene-laden joint fluid migrated and penetrated far from the bearing surface to the points of least resistance.  Thus, the concept of an effective joint space (i.e., all periprosthetic regions that are accessible to joint fluid and its particulate debris by the pumping action of the joint) was introduced into the orthopaedic lexicon.

Although the findings identified in this study were not necessarily new, the insights proffered by the authors radically altered our thoughts about osteolysis.  Using this concept of effective joint space, subsequent investigators and innovators identified methods and designs of hip replacements to retard osteolysis by limiting the generation and spread of particulate debris.

Thus, the 1990s were marked by the development of solid acetabular cups, nonmodular monoblock components, improved liner locking mechanisms to avoid backside wear, circumferentially coated femoral stems, highly crossed-linked polyethylene to lessen abrasive wear, and metal and ceramic bearing surfaces.  As appreciated by most orthopaedic residents, the article also led to a generation of questions on the Orthopaedics In-Training Exam (OITE) about the importance of macrophages in the pathogenesis of osteolysis.

Recently, some investigators speculate on a more significant mechanical effect of metal-on-metal joint fluid in causing the pseudotumors and muscle damage/necrosis that is frequently evident.  Regardless of whether the primary effect of small particle-laden joint fluid is biologic or mechanical, I believe that the theory of effective joint space remains a valid anatomic concept for all arthroplasty surgeons.

Robert Bucholz, MD

JBJS Deputy Editor for Adult Reconstruction and Trauma

JBJS Reviews Editor’s Choice–Failed Total Knee Arthroplasty

Perhaps more than any other advance in orthopaedic surgery, total joint arthroplasty has improved the lives of millions of patients. Originally introduced in the form of hip replacement, nearly all of the major joints of the musculoskeletal system can now undergo arthroplasty, and total knee arthroplasty has established itself as one of the most successful interventions for reducing pain and improving function and quality of life. All total joint arthroplasties are associated with a risk of failure, and it is believed that, with the exception of the oldest patients, most individuals who undergo an arthroplasty will require a revision at some point during their lifetime. With total knee arthroplasty, advances in implant materials and design as well as operative technique have increased implant longevity and decreased the rate of revision to <5% within ten years.

As is typical of a successful intervention, surgeons who perform total knee arthroplasty recognize the need or opportunity to “push the envelope.” There is great demand for offering knee arthroplasty to younger, more active patients, and, in doing so, it is projected that the number of revision procedures will grow from the current annual incidence of 38,000 up to 270,000 by the year 2030. Thus, understanding the causes of failure will be essential for guiding future strategies.

In this month’s article by Bou Monsef et al., a systematic approach to identifying mechanisms of failure and appropriate treatment protocols for failed total knee arthroplasty are introduced. The authors make the important point that avoiding operative intervention before a diagnosis is made, even in cases of pain with no clear etiology, is essential. Individual discussions on the roles of infection, loosening and component failure, instability, stiffness, patellofemoral complications, and even neuromas are presented and placed in their proper perspective.

Indeed, one of the greatest frustrations in orthopaedic practice is the inability to identify the causative factors for a condition. The failure of a total knee arthroplasty may be associated with one or more contributing factors, including rare and unusual conditions such as the formation of heterotopic bone, the development of complex regional pain syndrome, the occurrence of hemarthrosis, and even hypersensitivity to certain metals. Interestingly, up to 17% of the general population expresses some sensitivity to the metals used in total knee implants such as nickel, chromium, and cobalt.

Failure of total knee arthroplasty can be devastating to the patient, but early diagnosis and careful systematic analysis of the potential etiologies can lead to a favorable outcome. This article provides a clear and concise approach to this problem and is a “must read” for surgeons who perform this operation now and the residents and fellows who will be caring for these patients in the decades to come.

Thomas A. Einhorn, MD, Editor

EHR is Top-of-Mind Tech for Orthopaedic Practice Management

In a recent survey by MedData Group, 65% of 254 physicians spanning all subspecialties and practice sizes said they expect electronic health records (EHRs) to have the greatest practice impact among all medical technologies in 2015. Among orthopaedists, 78% ranked EHRs as being the most influential practice technology. Diagnostic technologies ranked a distant second among physicians, but twice as many as last year considered this area of technology to be significant. The survey found that overall practice-management priorities in 2015 will focus on two areas: successful implementation of ICD-10 and better quality care for patients.

EHR chart