Prevalence of incidental distal biceps signal changes on magnetic resonance imaging

BACKGROUND

Knowledge of the base rate of signal changes consistent with distal biceps tendinopathy on magnetic resonance imaging (MRI) has the potential to influence strategies for diagnosis and treatment of people that present with elbow pain. The aim of this study is to measure the prevalence of distal biceps tendon signal changes on MRIs of the elbow by indication for imaging.

METHODS

MRI data for 1,306 elbows were retrospectively reviewed for mention of signal change in distal biceps tendon. The reports were sorted by indication.

RESULTS

Signal changes consistent with distal biceps tendinopathy were noted in 197 of 1,306 (15%) patients, including 34% of patients with biceps pain, 14% of patients with unspecified pain, and 8% of patients with a specific non-biceps indication. Distal biceps tendon changes noted on radiology reports were associated with older age, male sex, and radiologists with musculoskeletal fellowship training.

CONCLUSIONS

The finding that distal biceps MRI signal changes consistent with tendinopathy are common even in asymptomatic elbows reduces the probability that symptoms correlate with pathology on imaging. The accumulation of signal changes with age, also independent of symptoms, suggests that tendon pathology persists after symptoms resolve, that some degree of distal biceps tendinopathy is common in a human lifetime, and that tendinopathy may often be accommodated without seeking care. Level of evidence: IV.

Factors Associated With Patient Satisfaction Measured Using an Iterative Scale

BACKGROUND AND OBJECTIVES

Patient experience measures tend to have notable ceiling effects that make it difficult to learn from gradations of satisfaction to improve care. This study tested 2 different iterative satisfaction measures after a musculoskeletal specialty care visit in the hope that they might have less ceiling effect. We measured floor effects, ceilings effects, skewness, and kurtosis of both questionnaires. We also assessed patient factors independently associated with the questionnaires and the top 2 possible scores.

METHODS

In this cross-sectional study, 186 patients completed questionnaires while seeing 1 of 11 participating orthopedic surgeons in July and August 2019; the questionnaire measured: (1) demographics, (2) symptoms of depression, (3) catastrophic thinking in response to nociception, (4) heightened illness concerns, and (5) satisfaction with the visit on 2 iterative satisfaction scales. Bivariate and multivariable analyses sought associations of the explanatory variable with the satisfaction scales.

RESULTS

There is a small correlation between the 2 scales ( r = 0.27; P < .001). Neither scale had a floor effect and both had a ceiling effect of 45%. There is a very small correlation between greater health anxiety and lower satisfaction measured with one of the scales ( r = -0.16; P = .05).

CONCLUSION

An iterative satisfaction questionnaire created some spread in patient experience data, but could not limit ceiling effects. Additional strategies are needed to remove ceiling effects from satisfaction measures.

Association between open tibia fractures and acute compartment syndrome: A retrospective cohort study

BACKGROUND

Studies on the association of open tibia fractures and acute compartment syndrome (ACS) show confusing results, with some papers highlighting a positive association, and others failing to do so. The aim of this study was to determine if an open tibia fracture is at increased risk of ACS occurrence, when compared to a closed fracture.

HYPOTHESIS

Skin injury in the setting of an open tibia fracture does not prevent from ACS occurrence, because the energy transmitted to the limb during trauma may lead to soft tissue lesions, including skin lacerations and ACS.

PATIENTS AND METHODS

In total, 711 consecutive adult patients (mean age 44.6 years; 65.8% males) sustaining 725 tibia fractures between 01.01.2005 and 31.12.2009 were included in this retrospective study. The outcome measure was ACS. The following variables were assessed: soft tissue condition, age, sex, low- vs. high-energy injury, type of fracture, associated contiguous skeletal injury. A logistic regression model was used and adjustment was performed for age and sex.

RESULTS

ACS occurred in 10.4% of proximal intra-articular fractures, 10.4% of extra-articular fractures and 3.3% of distal intra-articular fractures, and in 8.7% of closed fractures, 7.8% of open Gustilo 1 fractures and 13.3% of open Gustilo 2 and 3 fractures. Open lesions were not associated with ACS when tibia fractures were considered as a whole. When stratifying by types of fractures, open Gustilo 2 and 3 lesions were associated with ACS in proximal intra-articular fractures (p=0.048). There was no association with closed or any type of open lesions for extra-articular fractures. There were not enough ACS cases among distal intra-articular fractures to draw conclusions.

DISCUSSION

As ACS may occur with any type of open tibia fractures, clinicians should not be wrongly reassured by an open fracture, assuming that the wound would relieve the pressure inside the muscle compartments. There is a weak association between open Gustilo 2 and 3 lesions and ACS in proximal intra-articular fractures only. These findings are important for surgeons treating these injuries, especially by intubated, sedated or obtunded patients.

LEVEL OF EVIDENCE

III; retrospective diagnostic study.

People Have Mixed Reactions to Both Physiological and Psychological Explanations of Disproportionate Pain

BACKGROUND

There are two general frameworks that conceptualize pain that is more intense or persistent than expected based on measurable pathologic findings: the psychological (unhelpful thoughts and emotions) and the physiological (purported nervous system dysfunction, such as central sensitization). Some clinicians believe people will be more receptive to a physiological conceptualization. Prior quantitative research demonstrated that carefully crafted psychological explanations are rated similarly to crafted physiological explanations, with relatively mixed reactions. This qualitative study was undertaken in parallel with that quantitative study to help develop effective communication and treatment strategies by identifying specific thoughts and feelings (themes) regarding the physiological and psychological conceptualizations of disproportionate pain that make people more or less comfortable considering comprehensive, biopsychosocial treatment approaches.

QUESTION/PURPOSE

What themes arise in patient thoughts and feelings regarding physiological and psychological conceptualizations of pain that is more intense or persistent than expected?

METHODS

We sought to understand the experience of considering pain as a biopsychosocial experience (phenomenology approach) by studying the thoughts and feelings that arise as people seeking care for arm and back pain engage with physiological and psychological conceptualizations of pain that is more intense or persistent than one would expect based on the pathology. We recruited 29 patients presenting for upper extremity or back pain specialty care at one of two urban offices, intentionally recruiting people of various ages, genders, backgrounds, socioeconomic status, as well as type and duration of pain (purposive sampling). The 29 patients included 18 women and 11 men (16 married, 15 non-White, 20 with arm pain) with a median (interquartile range) age of 62 years (42 to 67). The interviews were conducted by a trained woman orthopaedic surgeon interviewer using a semistructured interview guide soliciting participants' thoughts and feelings about a physiological explanation (nerves in the central nervous system stuck in the on position can make pain more intense) and a psychological explanation (unhelpful thoughts and feelings of distress can make pain more intense) for pain more intense or persistent than expected. The interviews were transcribed and themes were identified as the data were collected. Based on current experimental evidence, including what is known about the physiological effects of thoughts, feelings, and context (placebo/nocebo effects), we assumed an underlying physiological basis for pain that is variably experienced and expressed (mixed postpositive/interpretive approach). Themes were identified in the interview transcripts systematically by two coders and then discussed with the entire research team to arrive at consensus. We stopped enrolling patients when the authors agreed that additional themes did not arise in five consecutive interviews.

RESULTS

The following themes and interpretations were derived from the analysis: Neither the physiological nor the psychological explanation for disproportionate pain (1) avoided the stigma associated with mental health, (2) was consistently understood, (3) provided a consistent sense of control, (4) consistently provided hope, and (5) represented the stress and emotion of disproportionate or persistent pain. The physiological explanation also generated mixed reactions regarding whether or not it: (1) was a useful point of conversation, (2) was reassuring or frightening, and (3) supported physiological or psychological treatments. The psychological explanation made some people feel worse.

CONCLUSION

People have mixed reactions to both physiological and psychological explanations of disproportionate pain. As such, without direction on content, communication might be most effective by focusing on relational aspects, such as emotional connection and trust.

CLINICAL RELEVANCE

Although there is room to improve the content of strategies for explaining more pain than expected to patients, our findings extend the discoveries of others in highlighting the need for tailored relational communication strategies that prioritize feeling heard, validated, and accompanied.

Does Resiliency Mediate the Association of Psychological Adaptability with Limitations and Pain Intensity after Upper Extremity Trauma?

BACKGROUND

Given the influence of psychosocial factors on musculoskeletal symptoms and limitations, this study assessed if the ability of resilience (an individual's ability to adapt under stress) mediates the association of psychological adaptability with magnitude of physical limitations and pain intensity during recovery from an upper extremity injury.

METHODS

A total of 107 patients were enrolled in this prospective, longitudinal, observational cohort study. Patients completed the Patient-Reported Outcomes Measurement Information System Physical Function (PROMIS PF), an 11-point ordinal measure of pain intensity, the Brief Resilience Scale (BRS), and the Psychological Adaptation Scale (PAS). We used structural equation modeling to assess the mediation effect by resiliency and psychological adaptability on patient-reported disability and pain at initial assessment and after three months.

RESULTS

PAS and BRS were not independently associated with PROMIS PF or pain intensity at enrollment or after three months, so it was not possible to assess if resiliency mediated the association of psychological adaptability with physical function or pain. There were no factors independently associated with resilience.

CONCLUSION

General measures of psychological adaptability and resiliency do not correlate with symptoms and limitations as well as specific measures of adaptiveness in response to nociception.

SEDAR/SECCE ECMO management consensus document

ECMO is an extracorporeal cardiorespiratory support system whose use has been increased in the last decade. Respiratory failure, postcardiotomy shock, and lung or heart primary graft failure may require the use of cardiorespiratory mechanical assistance. In this scenario perioperative medical and surgical management is crucial. Despite the evolution of technology in the area of extracorporeal support, morbidity and mortality of these patients continues to be high, and therefore the indication as well as the ECMO removal should be established within a multidisciplinary team with expertise in the area. This consensus document aims to unify medical knowledge and provides recommendations based on both the recent bibliography and the main national ECMO implantation centres experience with the goal of improving comprehensive patient care.

Pain during physical examination of a healing upper extremity fracture

The evidence that symptom intensity and magnitude of limitations correlate with thoughts and emotions means that subjective signs, such as pain with physical examination, reflect both physical and mental health. During a 1-month evaluation of a rapidly healing upper extremity fracture with no risk of nonunion, 117 people completed measures of adaptiveness to pain and pain during the physical examination. Greater pain during examination correlated with less adaptive responses to pain and older age. This finding raises questions about using tenderness to assess fracture union.Level of evidence: II.

Can Crafted Communication Strategies Allow Musculoskeletal Specialists to Address Health Within the Biopsychosocial Paradigm?

BACKGROUND

Musculoskeletal specialists who attempt to discuss the connection between mental health (thoughts and emotions) and physical health (symptom intensity and activity tolerance) with patients, may fear that they risk offending those patients. In a search for language that creates comfort with difficult conversations, some specialists favor a biomedical framework, such as central sensitization, which posits abnormal central neuron activity. Without addressing the relative accuracy of mind- or brain-based conceptualizations, we addressed crafted and practiced communication strategies as conversation starters that allow specialists to operate within a biopsychosocial framework without harming the relationship with the patient.

QUESTIONS/PURPOSES

We measured (1) patient resonance with various explanations of the mind-body connection, including examples of both mind- and brain-based communication strategies, and (2) factors associated with resonance and emotional reactions to the explanations.

METHODS

In this cross-sectional study, all adult new and returning patients who were literate in English and who attended several musculoskeletal specialty offices were invited to complete questionnaires addressing reactions to one of seven explanations of the mind-body connection assigned using a random number generator. Acknowledging that the relative accuracy of mind-based and nerve- or brain-based strategies are speculative, we developed the following conversation starters: two explanations that were cognitively framed ("the mind is a great story teller"; one positively framed and one negatively framed), two emotionally framed explanations ("stressed or down"; one positively framed and one negatively framed), one mentioning thoughts and emotions in more neutral terms ("mind and body work together … thoughts and emotions affect the way your body experiences pain"), and two biomedical neurophysiology-based explanations ("nerves get stuck in an over-excited state" and "overstimulated nerves"), all crafted with the assistance of a communication scholar. It was unusual for people to decline (although the exact number of those who did was not tracked) and 304 of 308 patients who started the questionnaires completed them and were analyzed. In this sample, 51% (155 of 304) were men, and the mean ± SD age was 49 ± 17 years. Reactions were measured as resonance (a 1 to 5 Likert scale regarding the degree to which the stated concept aligns with their understanding of health and by inference is a comfortable topic of discussion) and self-assessment manikins using circled figurines to measure feelings of happiness (frowning to smiling figures), stimulation/excitement (a relaxed sleepy figure to an energized wide-eyed figure), and security/control (small to large figures). These are commonly used to quantify the appeal and emotive content of a given message. Patients also completed surveys of demographics and mental health. Multilevel multivariable linear regression models were constructed to assess factors associated with resonance, happiness, excitement, and control.

RESULTS

Controlling for potential confounding variables such as demographics and mental health measures, a relatively neutral biopsychosocial explanation ("mind and body work together") had the greatest mean resonance (4.2 ± 0.8 versus 3.8 ± 0.9 for the other explanations; p < 0.01) and the largest regression coefficient for resonance (0.78 [95% confidence interval 0.41 to 1.15]). The next-most-resonant explanations were biomedical ("excitable nerves", "over-excited state"). Biopsychosocial explanations that mention stress, distress, or cognitive bias ("mind is a great storyteller") had lower resonance. People with greater unhealthy cognitive bias regarding pain (more catastrophic thinking) were less comfortable with all the explanations (lower resonance, regression coefficient -0.03 [95% CI -0.06 to -0.01]). Emotional reactions were relatively comparable with the exception that people felt less control and security with specific explanations such as "excitable nerves" and "mind is a great storyteller."

CONCLUSION

Crafted communication strategies allow musculoskeletal specialists to address health within the biopsychosocial paradigm without harming their relationship with the patient.

CLINICAL RELEVANCE

Musculoskeletal specialists may be the first clinicians to notice mental health opportunities. It may be helpful for them to develop and practice effective communication strategies that make mental health a comfortable topic of discussion.

The Correlation of Communication Effectiveness and Patient Satisfaction

This study assessed the correlation of 9 questions addressing communication effectiveness (the Communication Effectiveness Questionnaire [CEQ]) with other patient-reported experience measures (PREMs; satisfaction, perceived empathy) as well as patient-reported outcome measures (PROMs; pain intensity, activity tolerance) in patients with musculoskeletal illness or injury. In a cross-sectional study, 210 patients visiting an orthopedic surgeon completed the CEQ and measures of satisfaction with the visit, perceived empathy, pain intensity, and activity tolerance. We evaluated correlations between CEQ and other PREMs and CEQ and PROMs. We measured ceiling effects of the PREMs. Communication effectiveness correlated moderately with other PREMs such as satisfaction (ρ = 0.54; P < .001) and perceived empathy (ρ = 0.54; P < .001). Communication effectiveness did not correlate with PROMs: pain intensity (ρ = -0.01; P = .93) and activity tolerance (ρ = -0.05; P = .44). All of the experience measures have high ceiling effects: perceived empathy 37%, satisfaction 80%, and CEQ 46%. The observation of notable correlations of various PREMs, combined with their high ceiling effects, direct us to identify a likely common statistical construct (which we hypothesize as "relationship") accounting for variation in PREMs, and then develop a PREM which measures that construct in a manner that results in a Gaussian distribution of scores. At least within the limitations of current experience measures, there seems to be no association between illness (PROMs) and experience (PREMs).

Misperception of Disease Onset in People with Gradual-Onset Disease of the Upper Extremity

BACKGROUND

Misperception that an established, gradual-onset disease such as osteoarthritis started when the symptoms were first noticed might lead to testing and treatment choices that are inconsistent with what matters most to a patient. In the present study, the primary null hypothesis was that there are no factors associated with patient-reported symptom duration (in months). The secondary null hypotheses were that there are no factors independently associated with (1) a sudden versus gradual perception of disease onset, (2) an event or injury-related versus age-related perceived cause of disease onset, and (3) the magnitude of physical limitations.

METHODS

In this cross-sectional study, 121 patients with an atraumatic, established, gradual-onset condition of the upper extremity completed a demographic questionnaire, measures of mental health (symptoms of depression and anxiety, worst-case thinking, and self-efficacy [the ability to adapt and continue with daily activity] when in pain), measurement of the magnitude of upper extremity-specific limitations, and questions about the perceived course and cause of the disease.

RESULTS

The median patient-reported symptom duration was 12 months (interquartile range, 3 to 36 months). Twenty-two patients (18%) perceived their disease as new, and 29 patients (24%) believed that the condition was related to ≥1 event (injury) rather than being time and age-related. In multivariable analysis, patients with Medicare insurance were independently associated with longer reported symptom duration (in months). Greater self-efficacy was associated with longer symptom duration in bivariate, but not multivariable, analysis. No factors were independently associated with a sudden versus gradual onset of symptoms. Hispanic ethnicity and federal, county, or no insurance were independently associated with the perception that the problem was caused by an injury or event.

CONCLUSIONS

Approximately 1 in 5 patients misperceived new symptoms as representing a new disease, often as a type of injury. Misperception of the pathology as new had a limited association with unhealthy thoughts and is likely generally responsive to reorientation. We speculate that gentle, strategic reorientation of misperception can protect patients from choices inconsistent with their values.

Influenza Vaccination Is Not Associated with Increased Number of Visits for Shoulder Pain

BACKGROUND

Shoulder injury from vaccination was approved for automatic compensation from the Vaccine Injury Compensation Program (VICP)-a federal government program started in 1988 to shield the manufacturers of childhood vaccines from liability. The approval was made on the basis of case reports rather than experimental evidence. This, combined with the addition of influenza vaccination to the VICP in 2005 (which broadened coverage to include adults) and other social factors, was associated with a rapid rise in the number of claims of shoulder injury from vaccination over the last decade, which now account for more than half of all claims to the VICP. Given the high prevalence of newly symptomatic sources of shoulder pain such as rotator cuff tendinopathy, combined with the high prevalence of annual influenza vaccinations, there is a substantial risk of overlap leading to the post hoc ergo propter hoc fallacy ("after this, therefore because of this") contributing to misdiagnosis and inappropriate management of patients that perceive injury from vaccination. Records of medical care after a large number of vaccinations have a good chance of detecting serious shoulder pathology, even it is uncommon, which would result in an increased prevalence of visits for shoulder problems and specific types of shoulder pathology.

QUESTIONS/PURPOSES

Is there a difference in the proportion of visits for shoulder pain within 3 months before and after vaccination among students and faculty receiving an influenza vaccination in the shoulder?

METHODS

We studied people who were vaccinated for influenza between 2009 and 2018 at a university health service. During the study period, a comprehensive billing database identified 24,206 influenza vaccinations administered to 12,870 people (median age 20 years, range 16-77; 57% women). We had 80% power to detect a 0.1% increase in the proportion of shoulder problems after vaccination compared with before vaccination. Visits with coded ICD-9 shoulder diagnoses were identified from the electronic medical record. We compared the proportion of shoulder evaluations within 3 months before and 3 months after vaccination.

RESULTS

With the numbers available, the proportion of visits for shoulder problems were not different before (1.1% [52 of 4801]) and after vaccination (1% [40 of 3977], risk ratio 1.1 [95% CI 0.8 to 1.5]; p = 0.72). Among all vaccinations, 49% (11,834 of 24,206) were preceded or followed by an appointment within 3 months before (20% [4801 of 24,206]), after (16% [3977]), or both before and after (13% [3056]) vaccine administration, and 1.4% (170) of these visits were related to a shoulder issue. The most common reason for shoulder-related appointments was atraumatic shoulder pain (79% [134 of 170]).

CONCLUSIONS

Shoulder symptoms sufficient to seek care are notably common, even among relatively young adults, and are not more common after vaccination. Although this does not rule out an important rare pathology specific to vaccination, it seems important to consider the potential harms of assuming, based largely on chronology, that persistent shoulder pain after vaccination-something expected to be common based merely on the anticipated frequency of overlap of vaccination and common shoulder problems-represents harm from vaccine.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Factors Associated With Patient Satisfaction Measured Using a Guttman-Type Scale

Patient experience measures such as satisfaction are increasingly tracked and incentivized. Satisfaction questionnaires have notable ceiling effects that may limit learning and improvement. This study tested a Guttman-type (iterative) Satisfaction Scale (GSS) after a musculoskeletal specialty care visit in the hope that it might reduce the ceiling effect. We measured floor effects, ceiling effects, skewness, and kurtosis of GSS. We also assessed factors independently associated with GSS and the top 2 possible scores. In this cross-sectional study, 164 patients seeing an orthopedic surgeon completed questionnaires measuring (1) a demographics, (2) symptoms of depression, (3) catastrophic thinking in response to nociception, (4) heightened illness concerns, and (5) satisfaction with the visit (GSS). Bivariate and multivariable analyses sought associations of the explanatory variable with total GSS and top 2 scores of GSS. Accounting for potential confounding using multivariable analysis, lower satisfaction was independently associated with greater symptoms of depression (β: -0.03; 95% CI: -0.05 to -0.00; P = .047). The top 2 scores of the GSS were independently associated with women (compared to men: odds ratio [OR]: 2.12, 99% CI: 1.01-4.45, P = .046) and lower level of education (masters' degree compared to high school; OR: 0.16, 95% CI: 004-0.61, P = .007). The GSS had no floor effect, a ceiling effect of 38%, a skewness of -0.08, and a kurtosis of 1.3. The 38% ceiling effect of the iterative (Guttman-style) satisfaction measure is lower than ordinal satisfaction scales, but still undesirably high. Alternative approaches for reducing the ceiling effect of patient experience measures are needed.

Attempts to Limit Censoring in Measures of Patient Satisfaction

Background:

Measures of patient satisfaction are increasingly used to measure patient experience. Most satisfaction measures have notable ceiling effects, which limits our ability to learn from variation among relatively satisfied patients. This study tested a variety of single-question satisfaction measures for their mean overall score, ceiling and floor effect, and data distribution. In addition, we assessed the correlation between satisfaction and psychological factors and assessed how the various methods for measuring satisfaction affected net promoter scores (NPSs).

Methodology:

A total of 212 patients visiting orthopedic offices were enrolled in this randomized controlled trial. Patients were randomized to 1 of 5 newly designed, single-question satisfaction scales: (a) a helpfulness 11-point ordinal scale from 0 to 10, (b) a helpfulness ordinal 11-point scale from 0 to 5 (ie, with 1.5, 2.5, etc), (c) a helpfulness 100-point slider, (d) a satisfaction 11-point ordinal scale from 0 to 10, and (e) a willingness to recommend 11-point ordinal scale from 0 to 10. Additionally, patients completed the 2-item Pain Self-Efficacy Questionnaire (PSEQ-2), 5-item Short Health Anxiety Inventory (SHAI-5) Scale, and Patient-Reported Outcomes Measurement Information System (PROMIS) Depression. We assessed mean and median score, ceiling and floor effect, and skewness and kurtosis for each scale. Spearman’s correlation tests were used to test correlations between satisfaction and psychological status. Finally, we assessed the NPS for the various scales.

Results:

Ceiling effects ranged from 29% to 68%. The 11-point ordinal helpfulness scale from 0 to 10 had the least ceiling effect (29%). All of the scales were asymmetrically distributed, with the 11-point ordinal scale from 0 to 5 having the most Gaussian distribution (skew = 0.64 and kurtosis = 2.3). Satisfaction scores did not correlate with psychological factors: PSEQ-2 (r = 0.04; P = .57), SHAI-5 (r = 0.01; P = .93), and PROMIS Depression (r = −0.04; P = .61). Net promoter scores varied substantially by scale design, with higher scores corresponding with greater ceiling effects.

Conclusions:

Variations in scale types, text anchors, and lead-in statements do not eliminate the ceiling effect of single-question measures of satisfaction with a visit to an orthopedic specialist. Further studies might test other scale designs and labels.

Level of Evidence:

Diagnostic; Level II

Clinical and radiographic predictors of acute compartment syndrome in the treatment of tibial shaft fractures: a retrospective cohort study

Background

The purpose of this study was to evaluate the association between epidemiological, clinical and radiographic factors of patients with tibial shaft fractures and the occurrence of acute compartment syndrome.

Methods

270 consecutive adult patients sustaining 273 tibial shaft fractures between January 2005 and December 2009 were included in this retrospective cohort study. The outcome measure was acute compartment syndrome. Patient-related (age, sex), fracture-related (high- vs. low-energy injury, isolated trauma vs. polytrauma, closed vs. open fracture) and radiological parameters (AO/OTA classification, presence or absence of a noncontiguous tibial plateau or pilon fracture, distance from the centre of the tibial fracture to the talar dome, distance between tibial and fibular fracture if associated, and angulation, translation and over-riding of main tibial fragments) were evaluated regarding their potential association with acute compartment syndrome. Univariate analysis was performed and each covariate was adjusted for age and sex. Finally, a multivariable logistic regression model was built, and odds ratios and 95% confidence intervals were obtained. Statistical significance was defined as p < 0.05.

Results

Acute compartment syndrome developed in 31 (11.4%) cases. In the multivariable regression model, four covariates remained statistically significantly associated with acute compartment syndrome: polytrauma, closed fracture, associated tibial plateau or pilon fracture and distance from the centre of the tibial fracture to the talar dome ≥15 cm.

Conclusions

One radiological parameter related to the occurrence of acute compartment syndrome has been highlighted in this study, namely a longer distance from the centre of the tibial fracture to the talar dome, meaning a more proximal fracture. This observation may be useful when clinical findings are difficult to assess (doubtful clinical signs, obtunded, sedated or intubated patients). However, larger studies are mandatory to confirm and refine the prediction of acute compartment syndrome occurrence. Radiographic signs of significant displacement were not found to be correlated to acute compartment syndrome development. Finally, the higher rate of acute compartment syndrome occurring in tibial shaft fractures associated to other musculoskeletal, thoraco-abdominal or cranio-cerebral injuries must raise the level of suspicion of any surgeon managing multiply injured patients.

Is There an Association Between Smoking Status and Prosthetic Joint Infection After Primary Total Joint Arthroplasty?

BACKGROUND

Recent reports highlighted the association between smoking and higher risk of postsurgical infections. The aim was to compare the incidence of prosthetic joint infection after primary total joint arthroplasty (TJA) according to smoking status.

METHODS

A prospective hospital registry-based cohort study was performed including all primary knee and hip TJAs performed between March 1996 and December 2013. Smoking status preoperatively was classified into never, former, and current smoker. Incidence rates and hazard ratios (HRs) for prosthetic joint infection according to smoking status were assessed within the first year and beyond.

RESULTS

We included 8559 primary TJAs (mean age 69.5 years), and median follow-up was 67 months. There were 5722 never, 1315 former, and 1522 current smokers. Incidence rates of infection within the first year for never, former, and current smokers were, respectively, 4.7, 10.1, and 10.9 cases/1000 person-years, comparing ever vs never smokers, crude and adjusted HRs were 2.35 (95% confidence interval [CI] 1.39-3.98) and 1.8 (95% CI 1.04-3.2). Beyond the first year, crude and adjusted HRs were 1.37 (95% CI 0.78-2.39) and 1.12 (95% CI 0.61-2.04).

CONCLUSION

Smoking increased the infection risk about 1.8 times after primary hip or knee TJA in both current and former smokers. Beyond the first year, the infection risk was similar to never smokers.

Impact of noise in holography with extended references in the low signal regime

Signal-to-noise ratio is a key factor in lensless imaging, particularly for low diffraction signal experiments in the single shot regime. We present our recent study of the noise impact on holography with extended references. Experimental data have been measured in single shot acquisition using an intense coherent soft X-ray high harmonic source. The impact of hardware and software noise under various detection conditions is discussed. A final comparison between single shot and multi-shot regimes is given.

Fourier transform holography with high harmonic spectra for attosecond imaging applications

We demonstrate a method of using a Fourier holographic technique to utilize attosecond soft x-ray pulses to image nanometer-scale objects. A discrete frequency comb of laser-generated high-order harmonics, yielding a train of attosecond pulses, has been used to record spatially and spectrally resolved images. The individual wavelengths were also combined to form a single image, albeit with lower spatial resolution, demonstrating the applicability of the method to using isolated attosecond pulses with continuous bandwidths.

Impact of wave front and coherence optimization in coherent diffractive imaging

We present single shot nanoscale imaging using a table-top femtosecond soft X-ray laser harmonic source at a wavelength of 32 nm. We show that the phase retrieval process in coherent diffractive imaging critically depends on beam quality. Coherence and image fidelity are measured from single-shot coherent diffraction patterns of isolated nano-patterned slits. Impact of flux, wave front and coherence of the soft X-ray beam on the phase retrieval process and the image quality are discussed. After beam improvements, a final image reconstruction is presented with a spatial resolution of 78 nm (half period) in a single 20 fs laser harmonic shot.

An analysis of the GLVQ algorithm

Generalized learning vector quantization (GLVQ) has been proposed in as a generalization of the simple competitive learning (SCL) algorithm. The main argument of GLVQ proposal is its superior insensitivity to the initial values of the weights (code vectors). In this paper we show that the distinctive characteristics of the definition of GLVQ disappear outside a small domain of applications. GLVQ becomes identical to SCL when either the number of code vectors grows or the size of the input space is large. Besides that, the behavior of GLVQ is inconsistent for problems defined on very small scale input spaces. The adaptation rules fluctuate between performing descent and ascent searches on the gradient of the distortion function.

Kinetics of in vitro lipolysis of human very low-density lipoprotein by lipoprotein lipase

BACKGROUND AND AIM

An initial step in the catabolism of triglyceride-rich lipoprotein involves the hydrolysis of the triglyceride moiety by lipoprotein lipase (LPL). As differences in the lipolytic behaviour of very low-density lipoprotein (VLDL) particles have been observed, it is possible that different VLDL particles have a different affinity to the enzyme, which means that their fate may partially depend on the LPL-mediated hydrolysis of their triglyceride content. Our aim was to determine whether variation in VLDL chemical composition affects their properties as a substrate for LPL.

METHODS AND RESULTS

Isolated VLDL was incubated in vitro with bovine LPL to determine substrate affinity. Under optimal assay conditions, free fatty acids were measured and the kinetic indicators for in vitro triglyceride hydrolysis (Km and Vmax) were calculated. VLDL cholesterol (VLDL-C), VLDL-apoB and the cholesterol/triglyceride ratio were assessed and the triglyceride/protein and triglyceride/apoB ratios were calculated as lipoprotein size estimators. VLDL-C, VLDL-apoB and the VLDL-C/triglyceride ratio positively correlated with Km: r = 0.52, p < 0.01; r = 0.52, p < 0.03; r = 0.69, p < 0.001 respectively. No correlation was found between the VLDL-triglyceride/protein or the VLDL-triglyceride/apoB ratios and Km (r = -0.20, and -0.06 respectively, p = not significant). Of the subjects' anthropometric characteristics, only the waist/hip ratio significantly correlated with Km: r = 0.63, p < 0.01.

CONCLUSIONS

In the present study, we investigated the substrate function of VLDL particles in vitro. Enzyme affinity seems to be associated with cholesterol-triglyceride content or the number of VLDL particles rather than particle size. It may be expected that VLDL with a low cholesterol/triglyceride ratio will be efficiently lypolised by LPL, thus leading to the formation of a smaller particle with atherogenic potential.

In vitro susceptibility of Mycobacterium fortuitum, Mycobacterium chelonae and Mycobacterium avium against some quinolones

The in vitro susceptibility of Mycobacterium fortuitum, Mycobacterium chelonae and Mycobacterium avium to ciprofloxacin, norfloxacin and ofloxacin was studied by the agar dilution method. All strains of Mycobacterium fortuitum were inhibited by 2 mg/ml or less of these antimicrobial agents. Concentrations higher than achievable blood levels were necessary to inhibit Mycobacterium chelonae and Mycobacterium avium.