International multicentre review of perioperative management and outcome for catecholamine-producing tumours.

BACKGROUND: Surgery for catecholamine-producing tumours can be complicated by intraoperative and postoperative haemodynamic instability. Several perioperative management strategies have emerged but none has been evaluated in randomized trials. To assess this issue, contemporary perioperative management and outcome data from 21 centres were collected. METHODS: Twenty-one centres contributed outcome data from patients who had surgery for phaeochromocytoma and paraganglioma between 2000 and 2017. The data included the number of patients with and without α-receptor blockade, surgical and anaesthetic techniques, complications and perioperative mortality. RESULTS: Across all centres, data were reported on 1860 patients with phaeochromocytoma or paraganglioma, of whom 343 underwent surgery without α-receptor blockade. The majority of operations (78·9 per cent) were performed using minimally invasive techniques, including 16·1 per cent adrenal cortex-sparing procedures. The cardiovascular complication rate was 5·0 per cent overall: 5·9 per cent (90 of 1517) in patients with preoperative α-receptor blockade and 0·9 per cent (3 of 343) among patients without α-receptor blockade. The mortality rate was 0·5 per cent overall (9 of 1860): 0·5 per cent (8 of 517) in pretreated and 0·3 per cent (1 of 343) in non-pretreated patients. CONCLUSION: There is substantial variability in the perioperative management of catecholamine-producing tumours, yet the overall complication rate is low. Further studies are needed to better define the optimal management approach, and reappraisal of international perioperative guidelines appears desirable.

ANTECEDENTES: La cirugía de los tumores productores de catecolaminas puede complicarse por la inestabilidad hemodinámica intraoperatoria y postoperatoria. Se han propuesto distintas estrategias de manejo perioperatorio, pero ninguna ha sido evaluada en ensayos aleatorizados. Para evaluar este tema, se han recogido los datos de los resultados y del manejo perioperatorio contemporáneo de 21 centros. MÉTODOS: Veintiún centros aportaron datos de los resultados de los pacientes operados por feocromocitoma y paraganglioma entre 2000-2017. Los datos incluyeron el número de pacientes con y sin bloqueo del receptor α, las técnicas quirúrgicas y anestésicas, las complicaciones y la mortalidad perioperatoria. RESULTADOS: Los centros en su conjunto aportaron datos de 1.860 pacientes con feocromocitoma y paraganglioma, de los cuales 343 pacientes fueron intervenidos sin bloqueo del receptor α. La gran mayoría (79%) de las cirugías se realizaron utilizando técnicas mínimamente invasivas, incluido un 17% de procedimientos con preservación de la corteza suprarrenal. La tasa de complicaciones cardiovasculares fue de 5,0% en total; 5,9% (90/1517) en pacientes con bloqueo preoperatorio de los receptores α y 0,9% (3/343) en pacientes no pretratados. La mortalidad global fue del 0,5% (9/1860); 0,5% (8/1517) en pacientes pretratados y 0,3% (1/343) en pacientes no tratados previamente. CONCLUSIÓN: Existe una variabilidad sustancial en el manejo perioperatorio de los tumores productores de catecolaminas, aunque la tasa global de complicaciones es baja. Este estudio brinda la oportunidad para efectuar comparaciones sistemáticas entre estrategias de prácticas terapéuticas variables. Se necesitan más estudios para definir mejor el enfoque de manejo óptimo y parece conveniente volver a evaluar las guías internacionales perioperatorias.

Update on Biomaterials.

Biomaterials are essential to the use and development of successful treatments for orthopaedic patients. Orthopaedic surgeons need to understand the expected clinical performance and the effects of implants in patients. Recent attempts to improve implant durability have resulted in adverse effects related to biomaterials and their relationship to patients. Examples of these adverse effects in hip arthroplasty include wear and corrosion of metal-on-metal bearings, trunnions, and tapered modular neck junctions. Conversely, polymers and ceramics have shown substantial improvements in durability. Improved implant compositions and manufacturing processes have resulted in ceramic head and acetabular liners with improved material properties and the avoidance of voids, which have, in the past, caused catastrophic fractures. Cross-linking of polyethylene with radiation and doping with antioxidants has substantially increased implant durability and is increasingly being used in joint prostheses other than the hip. Additive manufacturing is potentially a transformative process; it can lead to custom and patient-specific implants and to improvements in material properties, which can be optimized to achieve desired bone responses. Orthopaedic surgeons must understand the material properties and the biologic effects of new or altered biomaterials and manufacturing processes before use. In addition, a clear benefit to the patient must be proven based on superior preclinical results and high-quality clinical investigations before orthopaedic surgeons use new or altered biomaterials.

Biomechanical properties of fixed-angle volar distal radius plates under dynamic loading.

PURPOSE: To evaluate and compare the biomechanical properties of 8 different locked fixed-angle volar distal radius plates under conditions designed to reflect forces seen in early fracture healing and postoperative rehabilitation. METHODS: We evaluated the Acumed Acu-Loc (Acumed, Hillsboro, OR), Hand Innovations DVR (Hand Innovations, Miami, FL), SBi SCS volar distal radial plate (Small Bone Innovations, Morrisville, PA), Synthes volar distal radius plate and EA extra-articular volar distal radius plate (Synthes, Paoli, PA), Stryker Matrix-SmartLock (Stryker Leibinger, Kalamazoo, MI), Wright Medical Technology Locon VLS (Wright Medical Technology, Arlington, TN), and Zimmer periarticular distal radius locking plate (Zimmer, Warsaw, IN). After affixing each plate to a synthetic corticocancellous radius, we created a standardized dorsal wedge osteotomy. Each construct had cyclic loading of 100 N, 200 N, and 300 N for a total of 6000 cycles. Outcomes, including load deformation curves, displacement, and ultimate yield strengths, were collected for each construct. RESULTS: The Wright plate was significantly stiffer at the 100 N load than the Zimmer plate and was stiffer at the 300 N load than 4 other plates. The Zimmer and Hand Innovations plates had the highest yield strengths and significantly higher yield strengths than the Wright, SBi, Stryker, and Synthes EA plates. CONCLUSIONS: Given the biomechanical properties of the plates tested, in light of the loads transmitted across the native wrist, all plate constructs met the anticipated demands. It seems clear that fracture configuration, screw placement, cost, and surgeon familiarity with instrumentation should take priority in selecting a plating system for distal radius fracture treatment. CLINICAL RELEVANCE: This study provides further information to surgeons regarding the relative strengths of different plate options for the treatment of distal radius fractures.

Reporting and notification of adverse events in orthopaedics.

Surgeons should know how to alert the US FDA when an adverse event occurs with a device that has been approved by the FDA. Documentation of such events is critically important to help identify trends concerning a particular device, thereby helping surgeons and other health care professionals avoid similar events. The FDA created the MedWatch program to aid health care professionals in reporting adverse events. Orthopaedic surgeons can use the program to get up-to-date alerts and help protect their patients.

Three cognitive markers of unconscious semantic activation.

A "response window" technique is described and used to reliably demonstrate unconscious activation of meaning by subliminal (visually masked) words. Visually masked prime words were shown to influence judged meaning of following target words. This priming-effect marker was used to identify two additional markers of unconscious semantic activation: (i) the activation is very short-lived (the target word must occur within about 100 milliseconds of the subliminal prime); and (ii) unlike supraliminal prime-target pairs, a subliminal pair leaves no memory trace that can be observed in response to the next prime-target pair. Thus, unconscious semantic activation is shown to be a readily reproducible phenomenon but also very limited in the duration of its effect.

Mortality after hip resurfacing versus total hip arthroplasty in young patients: a single surgeon experience.

BACKGROUND: The aims of this study were to investigate the following questions: (I) what are the mortality rates in patients age 55 years and younger who underwent a hip resurfacing arthroplasty (HRA) versus a standard total hip arthroplasty (THA)? (II) is the type of operation independently associated with mortality? METHODS: The database of a single high-volume surgeon was reviewed for patient's age 55 years and younger who underwent a hip arthroplasty between 2002 and 2010. This yielded 505 HRA patients and 124 THA patients. Chi-square analysis was performed to identify a 5-year mortality rate difference between the two cohorts. Multivariable Cox-Regression analyses were used to determine whether the type of operation was independently associated with mortality. RESULTS: There were 8 mortalities (1.6%) in the HRA cohort and 11 (8.9%) in the THA cohort, a statistically significant difference (P<0.001) on univariate analysis. Low mortality rates produced underpowered multivariate models. CONCLUSIONS: We have demonstrated that patients age 55 and younger who undergo HRA have a significantly lower mortality rate than those undergoing THA. This is consistent with multiple previously published large database studies.

Fixation strength comparison of onlay and inset patellar implants.

Patellar implant fixation continues to be one of the most troublesome areas in total knee arthroplasty (TKA). It has been reported that patellofemoral complications in TKA are responsible for almost half of all re-operations. The literature review revealed the rate of primary all-polyethylene patellar implant loosening ranging 1%-4.2% [Berend ME, Ritter MA, Keating EM, Faris PM, Crites BM. The failure of all-polyethylene patellar components in total knee replacement. Clin Orthop 2001;388:105-11, Chew JT, Stewart NJ, Hanssen AD, Luo ZP, Rand JA, An KN. Differences in patellar tracking and knee kinematics among three different total knee designs. Clin Orthop 1997;345:87-98, Barrack RL, Wolfe MW, Waldman DA, et al. Patellar resurfacing in total knee arthroplasty: a five to seven year follow-up of prospective, randomized, double-blind study. Proceedings of Sixty-Seventh Annual Meeting of the American Academy of Orthopaedic Surgeons 2000. p. 547]. The loosening rates for metal-backed or following patellar component revisions were considerably higher [Chew JT, Stewart NJ, Hanssen AD, Luo ZP, Rand JA, An KN. Differences in patellar tracking and knee kinematics among three different total knee designs. Clin Orthop 1997;345:87-98, Jordan LR, Sorrells RB, Jordan LC, Olivo JL. The long-term results of a metal-backed mobile bearing patella. Clin Orthop 2005;436:111-8, Berger RA, Lyon, JH, Jacobs JJ, Barden RM, Berkson EM, Sheinkop MB, et al. Problems with cementless total knee arthroplasty at 11 years followup. Clin Orthop 2001;392:196-207, Ritter MA, Pierce MJ, Zhou H, Meding JB, Faris PM, Keating EM. Patellar complications (total knee arthroplasty). Effect of lateral release and thickness. Clin Orthop 1999;367:149-57] Onlay and inset patellar components with variable fixation surface geometry are currently available for clinical use. The purpose of this study was to quantify the shear disassociation strength for both onlay and inset patellar fixation techniques. The variation in host material was minimized by the use of synthetic patellae, which has been previously validated in implant fixation studies. The testing revealed that inset patellar fixation resistance to shear disassociation was 25% higher than onlay patellae (p=0.0002).

Surface stress: a factor influencing ultra high molecular weight polyethylene durability in mobile-bearing knee design.

The continuing global interest in the use of total and unicompartmental mobile-bearing knee designs is manifest by an appreciation of their clinical performance. Like their fixed plateau counterparts, mobile-bearing knees are influenced by patient and surgical variables as well as design, material, and manufacturing choices. This article is a focused description of tibiofemoral surface stress distributions, as a predictor of in vivo material durability for three contemporary designs at positions encountered during daily activity.

Antibiotic-loaded bone cement for infection prophylaxis in total joint replacement.

Use of antibiotic-loaded bone cement for prophylaxis against infection is not indicated for patients not at high risk for infection who are undergoing routine primary or revision joint replacement with cement. The mechanical and elution properties of commercially available premixed antibiotic-loaded bone-cement products are superior to those of hand-mixed preparations. Use of commercially available antibiotic-loaded bone-cement products has been cleared by the United States Food and Drug Administration only for use in the second stage of a two-stage total joint revision following removal of the original prosthesis and elimination of active periprosthetic infection. Use of antibiotic-loaded bone cement for prophylaxis against infection in the second stage of a two-stage total joint revision involves low doses of antibiotics. Active infection cannot be treated with commercially available antibiotic-loaded bone cement as such treatment requires higher doses of antibiotics.

Alternative Reimbursement Models: Bundled Payment and Beyond: AOA Critical Issues.

The Bundled Payments for Care Improvement (BPCI) initiative was begun in January 2013 by the U.S. Centers for Medicare & Medicaid Services (CMS) through its Innovation Center authority, which was created by the U.S. Patient Protection and Affordable Care Act (PPACA). The BPCI program seeks to improve health-care delivery and to ultimately reduce costs by allowing providers to enter into prenegotiated payment arrangements that include financial and performance accountability for a clinical episode in which a risk-and-reward calculus must be determined. BPCI is a contemporary 3-year experiment designed to test the applicability of episode-based payment models as a viable strategy to transform the CMS payment methodology while improving health outcomes. A summary of the 4 models being evaluated in the BPCI initiative is presented in addition to the awardee types and the number of awardees in each model. Data from one of the BPCI-designated pilot sites demonstrate that strategies do exist for successful implementation of an alternative payment model by keeping patients first while simultaneously improving coordination, alignment of care, and quality and reducing cost. Providers will need to embrace change and their areas of opportunity to gain a competitive advantage. Health-care providers, including orthopaedic surgeons, health-care professionals at post-acute care institutions, and product suppliers, all have a role in determining the strategies for success. Open dialogue between CMS and awardees should be encouraged to arrive at a solution that provides opportunity for gainsharing, as this program continues to gain traction and to evolve.

Mobile-bearing knee systems: ultra-high molecular weight polyethylene wear and design issues.

In June 2004, the U.S. Food and Drug Administration Orthopaedic Advisory Panel recommended the reclassification of mobile-bearing knee systems for general use. This reflects the increasing use of mobile-bearing knee systems internationally, which is currently limited in the United States by regulatory requirement. Mobile-bearing knee systems are distinguished from conventional, fixed-plateau systems in that they allow dual-surface articulation between an ultra-high molecular weight polyethylene insert and metallic femoral and tibial tray components. Their in vivo success is dependent on patient selection, design, and material choice, as well as surgical precision during implantation. Laboratory and clinical experience extending over 25 years with individual systems suggests that mobile-bearing knee systems represent a viable treatment option for patients with knee arthrosis.

Soft-tissue balancing of the hip: the role of femoral offset restoration.

Inadequate soft-tissue balancing is a major yet often underemphasized cause of failure for primary and revision total hip arthroplasty. Accordingly, contemporary cemented and cementless hip prostheses have been designed with consideration of this issue, and this has substantially increased the long-term survival of total hip replacements. Therefore, it is important for orthopaedic surgeons to be familiar with the rationale, biomechanical principles, and clinical implications associated with soft-tissue balancing of the hip as well as strategies to avoid inadequate soft-tissue balancing and systematic techniques to restore adequate soft-tissue tensioning during total hip arthroplasty.

The rationale and performance of modularity in total hip arthroplasty.

Modularity in total hip arthroplasty design is an evolving concept that continues to receive citation in the clinical literature. The advantages of these systems include off-the-shelf flexibility for customizing proximal and distal canal filling, as well as accommodation of difficult situations of femoral deformity and bone loss. Clinical concerns in the application of modular femoral stem hip designs include the maintenance of anatomical stability within the femoral canal component dissociation, structural compromise at metal-metal interconnections due to cyclic microdisplacements (fretting), and the increased potential for metallic-wear debris generation. This article reviews the rationale and performance of typical modular systems.

Implicit social cognition: attitudes, self-esteem, and stereotypes.

Social behavior is ordinarily treated as being under conscious (if not always thoughtful) control. However, considerable evidence now supports the view that social behavior often operates in an implicit or unconscious fashion. The identifying feature of implicit cognition is that past experience influences judgment in a fashion not introspectively known by the actor. The present conclusion--that attitudes, self-esteem, and stereotypes have important implicit modes of operation--extends both the construct validity and predictive usefulness of these major theoretical constructs of social psychology. Methodologically, this review calls for increased use of indirect measures--which are imperative in studies of implicit cognition. The theorized ordinariness of implicit stereotyping is consistent with recent findings of discrimination by people who explicitly disavow prejudice. The finding that implicit cognitive effects are often reduced by focusing judges' attention on their judgment task provides a basis for evaluating applications (such as affirmative action) aimed at reducing such unintended discrimination.

Replicable unconscious semantic priming.

In 4 experiments, subjects classified visually presented target words as pleasant-unpleasant words or male-female first names. Prime words were similar (congruent) or dissimilar (incongruent) in meaning to targets. Brief duration of prime words (17, 33, or 50 ms), along with pre- and postmasking, prevented most subjects from perceiving their physical and semantic properties. By constraining response latencies to fall within a response window--a narrow time band that occurred earlier than subjects would ordinarily respond--these experiments consistently produced subliminal priming effects, indicated by greater error rates for incongruent than congruent priming trials. This conclusion was confirmed by analyzing magnitude of priming as a regression function of prime perceptibility using the method of A. G. Greenwald, M. R. Klinger, and E. S. Schuh (1995). The data of each experiment passed their significant-intercept criterion for demonstrating unconscious cognition.

Distinguishing unconscious from conscious cognition--reasonable assumptions and replicable findings: reply to Merikle and Reingold (1998) and Dosher (1998)

S. C. Draine and A. G. Greenwald (1998) demonstrated replicable unconscious semantic priming by combining a response window procedure, which increases priming effects by requiring rapid responding, and a regression analysis in which the regression intercept is a marker for unconscious cognition. The commentaries by B. A. Dosher (1998) and by P. M. Merikle and E. M. Reingold (1998) raise two questions about conclusions based on these methods: (a) Did Draine and Greenwald (1998) demonstrate an indirect effect (subliminal priming) in the absence of a direct effect (i.e., visibility of the subliminal priming words)? and (b) Did Draine and Greenwald (1998) demonstrate dissociation of conscious from unconscious cognition? The first question has reassuring responses that are reviewed here. The second question is answered by pointing out that although Draine and Greenwald (1998) did not claim to have established such dissociation, they provided data that advance the plausibility of that conclusion.

Activation by marginally perceptible ("subliminal") stimuli: dissociation of unconscious from conscious cognition.

Introduces a linear regression method for investigating unconscious cognition. For words that were obscured by simultaneous dichoptic masking, indirect effects (semantic priming) and direct effects (perceptual identification) were assessed in 20 experiments (total N = 2,026). When measures of both indirect and direct effects have rational zero points, a statistically significant intercept in the indirect-on-direct-measure regression shows that (a) the indirect effect occurred in the absence of the direct effect, and (b) unconscious cognition is involved. For a position discrimination task, but not for an evaluative decision task, indirect-on-direct regression showed the significant intercept effect. Although small in magnitude, this intercept effect provides the statistically most secure finding yet obtained of a much-sought and controversial data pattern--indirect effect with no direct effect. With one added assumption (which appears plausible for the present data), this pattern indicates that unconscious cognition is dissociated from (i.e., occurs separately from) conscious cognition.

Correcting for measurement error in detecting unconscious cognition: comment on Draine and Greenwald (1998)

A. G. Greenwald, M. R. Klinger, and E. S. Schuh (1995) have proposed a regression method for detecting unconscious cognition in experiments that obtain measures of indirect and direct effects of stimuli with suspected unconscious effects. Their indirect-on-direct-measure regression approach can produce misleading evidence for indirect effects in the absence of direct effects when the direct-effect measure has typical measurement error. This article describes an errors-in-variables variant of the regression method that corrects for error in the direct-effect measure. Applied to the uses of the regression method by S. C. Draine and A. G. Greenwald (1998) in this issue, the errors-in-variables method affirms substantial evidence for indirect effects in the absence of direct effects.

Finger joint contact areas and pressures.

Although the joints of the index finger are similar geometrically and kinematically, the occurrence of degenerative joint disease is more frequent and severe in the distal interphalangeal joint. Much circumstantial evidence exists to suggest a mechanical cause for the observed differences in frequency. This article presents the results of in vitro experiments designed to determine contact areas and average pressures in the joints of the human index finger for positions simulating tip pinch and power grasp. The results show that the highest average contact pressures do, in fact, occur in the distal interphalangeal joint. Average joint contact pressure correlates well with clinically observed patterns of frequency of degeneration and degenerative joint disease score. This correlation between clinical experience and experimental results indicates that mechanical stress is among the factors responsible for the initiation and/or propagation of degenerative joint disease in the joints of the finger.