HIIT Induces Stronger Shifts within the Peripheral T Cell Compartment Independent of Sex

Acute exercise induces changes within the T-cell compartment, especially in cytotoxic CD8+ memory subsets, depending on exercise intensity and duration. It is unclear whether exercise-induced changes in major T-cell subsets differ in response to acute high-intensity interval training (HIIT) or moderate-intensity continuous training (MICT) and whether sex-specific effects exist. Twenty-four recreationally active runners (females: n=12, 27.8±4.1years, 54.4±4.6 ml*kg-1*min-1; males: n=12, 31.6±3.8years, 58.9±7.7 ml*kg-1*min-1) participated in this randomized controlled crossover study, and conducted an energy- and duration-matched HIIT and MICT session. Blood was sampled before (T1), immediately (T2) and 1 h after exercise (T3). Flow cytometry was used to identify T-cell populations. HIIT decreased the proportion of CD8+ T-cells more pronounced at T3 compared to MICT (p=0.007), induced a significantly stronger increase in the CD8+ effector memory (TEM) cell proportion at T2 (p=0.032), and decreased CD4+ central memory proportion more pronounced at T2 (p=0.029). A decrease below baseline CD8+ TEM proportion at T3 was observed only after HIIT (p<0.001). No interaction effects between sexes were revealed. Taken together, HIIT represents a more potent stimulus to induce shifts mainly within the cytotoxic CD8+ T-cell compartment, thereby giving implications to investigate the role of HIIT on the cell´s effector phenotype and function in more detail.

Intensity- and time-matched acute interval and continuous endurance exercise similarly induce an anti-inflammatory environment in recreationally active runners: focus on PD-1 expression in Tregs and the IL-6/IL-10 axis

PURPOSE

Acute exercise elicits a transient anti-inflammatory state during the early recovery period. Since recent studies reported on regimen-specific effects on immune-related humoral factors and cellular subsets, this study compared the effects of intensity- and time-matched acute interval and continuous exercise on peripheral anti-inflammatory cellular and humoral immune parameters with a particular focus on the PD-1 expression in CD4+ regulatory T cells (Tregs).

METHODS

Twenty-four recreationally active runners (age: 29.7 ± 4.3 years, BMI: 22.2 ± 2.4, VO2peak: 56.6 ± 6.4 ml × kg-1 × min-1) participated in this crossover RCT. Each subject conducted a moderate continuous (MCE) and a high-intensity interval exercise (HIIE) session in a counterbalanced design. Blood was drawn before, immediately after, and 1 h after exercise. Treg subsets and levels of PD-1 and Foxp3 were assessed by flow cytometry. Serum levels of IL-10 and IL-6 were quantified by ELISA.

RESULTS

PD-1 levels on Tregs increased within the recovery period after HIIE (p < .001) and MCE (p <  0.001). Total counts of Tregs (HIIE: p = 0.044; MCE: p = .021), naïve Tregs (HIIE: p  < 0.001; MCE: p  < 0.001), and PD-1+ effector Tregs (eTregs) (HIIE: p = .002) decreased 1 h after exercise. IL-10 increased 1 h after HIIE (p < 0.001) and MCE (p = 0.018), while IL-6 increased immediately after both HIIE (p = 0.031) and MCE (p = 0.021). Correlations between changes in IL-6 and IL-10 (p = 0.017, r = 0.379) and baseline VO2peak and Treg frequency (p = 0.002, r = 0.660) were identified.

CONCLUSION

This is the first study that investigates PD-1 expression in circulating Tregs after acute exercise, revealing an increase in PD-1 levels on eTregs during the early recovery period after intensity- and time-matched HIIE and MCE. Future studies are needed to investigate the PD-1 signalosome in eTregs, together with the expression of key effector molecules (i.e., IL-10, TGF-β, IL-35, CTLA-4) to elucidate PD-1-dependent changes in cellular function. Based on changes in serum cytokines, this study further reveals a regimen-independent establishment of an anti-inflammatory milieu and underpins the role of the IL-6/IL-10 axis.

Maternal knowledge of recommendations for safe infant sleep and intentions for implementation - a cross sectional analysis of data from the KUNO-Kids birth cohort study

OBJECTIVES

Despite major advances in prevention, sudden infant death syndrome (SIDS) remains an important cause of infant mortality. The aim of our study was to determine actual knowledge and intentions to implement SIDS prevention measures among new mothers and to identify potential knowledge gaps for improved postpartum counselling strategies.

METHODS

Data was collected in a standardized interview from participants of the KUNO-Kids birth cohort study before discharge from maternity ward. The mothers did not receive any specific teaching prior to the interview.

RESULTS

The majority of 2,526 interviewed mothers were able to actively report important recommendations for safe infant sleep, including the exclusive face-up position. However, 154 mothers (9%) intended to position the newborn face-down sometimes or often. The most frequently envisaged sleeping furniture was a bedside sleeper (n=1,144, 47%), but 2.2% of mothers indicated that the intended default sleeping place for the newborn would be the parents' bed (which is discouraged by the recommendations). For 43% of the infants (n=1,079), mothers planned to have loose objects in the bed and 189 mothers (7%) intended to use a loose blanket. 22% of infants (n=554) will live in a household with a smoker. Multivariate regression showed a significant association of "good knowledge" with maternal age and with not being a single parent, whereas the household size was negatively associated.

CONCLUSION

Although the majority of mothers in our birth cohort were aware of many recommendations for safe infant sleep, our data also uncovered weaknesses in SIDS prevention knowledge and point to specific areas with potential for improved counselling.

Physical Exercise as Kynurenine Pathway Modulator in Chronic Diseases: Implications for Immune and Energy Homeostasis

Emerging evidence highlights the substantial role of the kynurenine pathway in various physiological systems and pathological conditions. Physical exercise has been shown to impact the kynurenine pathway in response to both single (acute) and multiple (chronic) exercise training stimuli. In this perspective article, we briefly outline the current knowledge concerning exercise-induced modulations of the kynurenine pathway and discuss underlying mechanisms. Furthermore, we expose the potential involvement of exercise-induced kynurenine pathway modulations on energy homeostasis (eg, through de novo synthesis of NAD+) and finally suggest how these modulations may contribute to exercise-induced benefits in the prevention and treatment of chronic diseases.

Cellular immune response to acute exercise: Comparison of endurance and resistance exercise

OBJECTIVES

Exercise-induced cellular mobilization might play a role in treatment and prevention of several diseases. However, little is known about the impact of different exercise modalities on immune cell mobilization and clinical cellular inflammation markers. Therefore, the present study aimed to investigate differences between acute endurance exercise (EE) and resistance exercise (RE) on cellular immune alterations.

METHODS

Twenty-four healthy men conducted an acute EE (cycling at 60% of peak power output) and RE (five exercise machines at 70% of the one-repetition maximum) session lasting 50 minutes in randomized order. Blood samples were collected before, after and one hour after exercise cessation. Outcomes included counts and proportions of leukocytes, neutrophils (NEUT), lymphocytes (LYM), LYM subsets, CD4/CD8 ratio, and the clinical cellular inflammation markers NEUT/LYM ratio (NLR), platelets/LYM ratio (PLR), and systemic immune inflammation index (SII).

RESULTS

Alterations in all outcomes were revealed except for CD8⁺ T cells, CD4/CD8 ratio, NLR, and PLR. EE induced a stronger cellular immune response and provoked alterations in more immune cell populations than RE. SII was altered only after EE.

CONCLUSION

An acute EE session causes a stronger mobilization of immune cells than RE. Additionally, SII represents an integrative marker to depict immunological alterations.

Exercise and the Kynurenine pathway: Current state of knowledge and results from a randomized cross-over study comparing acute effects of endurance and resistance training

INTRODUCTION

The essential amino acid tryptophan (TRP) is primarily degraded through the kynurenine (KYN) pathway, which is dysregulated in several chronic diseases. KYN pathway metabolites have immune- and neuro-modulatory properties and are involved in th de novo synthesis of nicotinamide adenine dinucleotide (NAD+). Currently, little evidence exists demonstrating that physical exercise may influence this pathway. However, differences between acute and chronic stimuli as well as the influence of exercise modalities remain to be investigated. Here, we provide an overview of existing studies and present results of a randomized cross-over trial on acute effects of a single-bout of resistance and endurance exercise.

METHODS

24 healthy male adults conducted both an acute endurance exercise (EE) and resistance exercise (RE) session. Blood samples were collected before, immediately after and one hour after cessation of each exercise session. Outcomes comprised serum levels of TRP, KYN, kynurenic acid (KA), quinolinic acid (QA) and calculated ratios. Gene expression of the enzymes indoleamine 2,3 dioxygenase (IDO) 1 and kynurenine aminotransferase (KAT) 4 was measured in peripheral blood mononuclear cells (PBMCs). Moreover, serum concentrations of the potential KYN pathway mediators interleukin (IL)-6 and cortisol were determined. Finally, we investigated baseline correlations between immune cell subsets, potential mediators and initial KYN pathway activation outcomes.

RESULTS

The KYN/TRP ratio correlated positively with IL-6 and CD56bright NK-cells and negatively with CD56dim NKcells. Expression of IDO1 in PBMCs correlated positively with IL-6, regulatory T-cells and CD56bright NK-cells, whereas negative correlations to cytotoxic T-cells and CD56dim NKcells were revealed. A significant time effect on KYN/TRP ratio was detected for RE. Regarding KA and KA/KYN ratio, an increase after exercise followed by a decrease at the follow- up measurement was revealed in EE. KAT4 expression also increased after exercise in EE. Moreover, elevated QA levels were observed after the EE session.

CONCLUSIONS

In contrast to chronic exercise interventions, single-bouts of endurance exercise provoke acute alterations on KYN pathway outcomes in humans. Our results indicate that EE induces stronger alterations than RE. Enhanced conversion of KYN to both, KA and QA suggest a peripheral KYN clearance, thereby preventing pathological accumulation within the CNS. Future acute and chronic exercise studies are needed to examine the role of NAD+ synthesis starting with TRP and the interplay between KYN pathway activation and mid- to long-term immunological modulations.

Influence of combined functional resistance and endurance exercise over 12 weeks on matrix metalloproteinase-2 serum concentration in persons with relapsing-remitting multiple sclerosis - a community-based randomized controlled trial

BACKGROUND

The relevance of regular moderate to intense exercise for ameliorating psychomotor symptoms in persons with multiple sclerosis (pwMS) is becoming increasingly evident. Over the last two decades, emerging evidence from clinical studies and animal models indicate immune regulatory mechanisms in both periphery and the central nervous system that may underlie these beneficial effects. The integrity of the blood-brain barrier as the main structural interface between periphery and brain seems to play an important role in MS. Reducing the secretion of proteolytic matrix metalloproteinases (MMP), i.e. MMP-2, as disruptors of blood-brain barrier integrity could have profound implications for MS.

METHODS

In this two-armed randomized controlled trial 64 participants with relapsing-remitting MS (RRMS) (EDSS 0-4.0) will be allocated to either an intervention group or a passive wait list control group. The intervention group will perform 60 min of combined functional resistance and endurance exercises 3x per week over a period of 12 weeks in a community-based and publicly available setting. Changes in serum concentration of MMP-2 will be the primary outcome. Secondary outcomes are numbers of immune cell subsets, soluble (anti-) inflammatory factors, physical capacity, cognitive performance, physical activity behavior, gait performance, and patient-reported outcomes. All outcome measures will be assessed at baseline and after week 12 with an additional blood sampling before, during and immediately after a single training session in week 6.

DISCUSSION

To our knowledge, this will be the first RCT to investigate both the acute and chronic effects of a community-based intense functional resistance and endurance exercise regimen in persons with RRMS. Combining analysis of biological and cognitive or psychological outcomes may provide a better understanding of the MS-specific symptomology.

TRIAL REGISTRATION

DRKS00017091; 05th of April, 2019; International Clinical Trials Registry Platform.

The Avon patellofemoral joint arthroplasty: two- to 18-year results of a large single-centre cohort

Aims

This study reports on the medium- to long-term implant survivorship and patient-reported outcomes for the Avon patellofemoral joint (PFJ) arthroplasty.

Patients and Methods

A total of 558 Avon PFJ arthroplasties in 431 patients, with minimum two-year follow-up, were identified from a prospective database. Patient-reported outcomes and implant survivorship were analyzed, with follow-up of up to 18 years.

Results

Outcomes were recorded for 483 implants (368 patients), representing an 86% follow-up rate. The median postoperative Oxford Knee Score (0 to 48 scale) was 35 (interquartile range (IQR) 25.5 to 43) and the median Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC, 0 to 100 scale) was 35 (IQR 25 to 53) at two years. There were 105 revisions, 61 (58%) for progression of osteoarthritis. All documented revisions were to primary knee systems without augmentation. The implant survival rate was 77.3% (95% confidence interval (CI) 72.4 to 81.7, number at risk 204) at ten years and 67.4% (95% CI 72.4 to 81.7 number at risk 45) at 15 years. Regression analysis of explanatory data variable showed that cases performed in the last nine years had improved survival compared with the first nine years of the cohort, but the individual operating surgeon had the strongest effect on survivorship.

Conclusion

Satisfactory long-term results can be obtained with the Avon PFJ arthroplasty, with maintenance of patient-reported outcome measures (PROMs), satisfactory survival, and low rates of loosening and wear. Cite this article: Bone Joint J 2018;100-B:1162-7.

The Hsp72 and Hsp90α mRNA Responses to Hot Downhill Running Are Reduced Following a Prior Bout of Hot Downhill Running, and Occur Concurrently within Leukocytes and the Vastus Lateralis

The leukocyte heat shock response (HSR) is used to determine individual's thermotolerance. The HSR and thermotolerance are enhanced following interventions such as preconditioning and/or acclimation/acclimatization. However, it is unclear whether the leukocyte HSR is an appropriate surrogate for the HSR in other tissues implicated within the pathophysiology of exertional heat illnesses (e.g., skeletal muscle), and whether an acute preconditioning strategy (e.g., downhill running) can improve subsequent thermotolerance. Physically active, non-heat acclimated participants were split into two groups to investigate the benefits of hot downhill running as preconditioning strategy. A hot preconditioning group (HPC; n = 6) completed two trials (HPC1_HOTDOWN and HPC2_HOTDOWN) of 30 min running at lactate threshold (LT) on -10% gradient in 30°C and 50% relative humidity (RH) separated by 7 d. A temperate preconditioning group (TPC; n = 5) completed 30 min running at LT on a -1% gradient in 20°C and 50% (TPC1_TEMPFLAT) and 7 d later completed 30 min running at LT on -10% gradient in 30°C and 50% RH (TPC2_HOTDOWN). Venous blood samples and muscle biopsies (vastus lateralis; VL) were obtained before, immediately after, 3, 24, and 48 h after each trial. Leukocyte and VL Hsp72, Hsp90α, and Grp78 mRNA relative expression was determined via RT-QPCR. Attenuated leukocyte and VL Hsp72 (2.8 to 1.8 fold and 5.9 to 2.4 fold; p < 0.05) and Hsp90α mRNA (2.9 to 2.4 fold and 5.2 to 2.4 fold; p < 0.05) responses accompanied reductions (p < 0.05) in physiological strain [exercising rectal temperature (-0.3°C) and perceived muscle soreness (~ -14%)] during HPC2_HOTDOWN compared to HPC1_HOTDOWN (i.e., a preconditioning effect). Both VL and leukocyte Hsp72 and Hsp90α mRNA increased (p < 0.05) simultaneously following downhill runs and demonstrated a strong relationship (p < 0.01) of similar magnitudes with one another. Hot downhill running is an effective preconditioning strategy which ameliorates physiological strain, soreness and Hsp72 and Hsp90α mRNA responses to a subsequent bout. Leukocyte and VL analyses are appropriate tissues to infer the extent to which the HSR has been augmented.

Abnormal loading and functional deficits are present in both limbs before and after unilateral knee arthroplasty

Unilateral knee replacement is often followed by a contralateral replacement in time and the biomechanics of the other knee before and after knee replacement remains poorly understood. The aim of this paper is to distinguish the features of arthritic gait in the affected and unaffected legs relative to a normal population and to assess the objective recovery of gait function post-operatively, with the aim of defining patients at risk of poor post-operative function. Twenty patients with severe knee OA but no pain or deformity in any other lower limb joint were compared to twenty healthy subjects of the same age. Gait analysis was performed and quadriceps and hamstrings co-contraction was measured. Fifteen subjects returned 1year following knee arthroplasty. Moments and impulses were calculated, principal component analysis was used to analyse the waveforms and a classification technique (the Cardiff Classifier) was used to select the most discriminant data and define functional performance. Comparing pre-operative function to healthy function, classification accuracies for the affected and unaffected knees were 95% and 92.5% respectively. Post-operatively, the affected limb returned to the normal half of the classifier in 8 patients, and 7 of those patients returned to normal function in the unaffected limb. Recovery of normal gait could be correctly predicted 13 out of 15 times at the affected knee, and 12 out of 15 times at the unaffected knee based on pre-operative gait function. Focused rehabilitation prior to surgery may be beneficial to optimise outcomes and protect the other joints following knee arthroplasty.

Trochleoplasty with a flexible osteochondral flap: results from an 11-year series of 214 cases

AIMS

The Bereiter trochleoplasty has been used in our unit for 12 years to manage recurrent patellar instability in patients with severe trochlea dysplasia. The aim of this study was to document the outcome of a large consecutive cohort of patients who have undergone this operation.

PATIENTS AND METHODS

Between June 2002 and August 2013, 214 consecutive trochleoplasties were carried out in 185 patients. There were 133 women and 52 men with a mean age of 21.3 years (14 to 38). All patients were offered yearly clinical and radiological follow-up. They completed the following patient reported outcome scores (PROMs): International Knee Documentation Committee subjective scale, the Kujala score, the Western Ontario and McMaster Universities Arthritis Index score and the short-form (SF)-12.

RESULTS

Outcomes were available for 199 trochleoplasties in 173 patients giving a 93% follow-up rate at a mean of 4.43 years (1 to 12). There were no infections or deep vein thromboses. In total, 16 patients reported further patella dislocation, giving an 8.3% rate of recurrence. There were 27 re-operations, giving a rate of re-operation of 14%. Overall, 88% were satisfied with the operation and 90% felt that their symptoms had been improved.

CONCLUSION

All PROMs improved significantly post-operatively except for the mental component score of the SF-12. Trochleoplasty performed using a flexible osteochondral flap is an effective treatment for recurrent patellar instability in patients with severe trochlea dysplasia and gives good results in the medium term. Cite this article: Bone Joint J 2017;99-B:344-50.

Downhill running and exercise in hot environments increase leukocyte Hsp72 (HSPA1A) and Hsp90α (HSPC1) gene transcripts

Stressors within humans and other species activate Hsp72 and Hsp90α mRNA transcription, although it is unclear which environmental temperature or treadmill gradient induces the largest increase. To determine the optimal stressor for priming the Hsp system, physically active but not heat-acclimated participants (19.8 ± 1.9 and 20.9 ± 3.6 yr) exercised at lactate threshold in either temperate (20°C, 50% relative humidity; RH) or hot (30°C, 50% RH) environmental conditions. Within each condition, participants completed a flat running (temperate flat or hot flat) and a downhill running (temperate downhill or hot downhill) experimental trial in a randomized counterbalanced order separated by at least 7 days. Venous blood samples were taken immediately before (basal), immediately after exercise, and 3 and 24 h postexercise. RNA was extracted from leukocytes and RT-quantitative PCR conducted to determine Hsp72 and Hsp90α mRNA relative expression. Leukocyte Hsp72 mRNA was increased immediately after exercise following downhill running (1.9 ± 0.9-fold) compared with flat running (1.3 ± 0.4-fold; P = 0.001) and in hot (1.9 ± 0.6-fold) compared with temperate conditions (1.1 ± 0.5-fold; P = 0.003). Leukocyte Hsp90α mRNA increased immediately after exercise following downhill running (1.4 ± 0.8-fold) compared with flat running (0.9 ± 0.6-fold; P = 0.002) and in hot (1.6 ± 1.0-fold) compared with temperate conditions (0.9 ± 0.6-fold; P = 0.003). Downhill running and exercise in hot conditions induced the largest stimuli for leukocyte Hsp72 and Hsp90α mRNA increases.

The efficacy of the self-paced V̇O2max test to measure maximal oxygen uptake in treadmill running

The novel self-paced, cycle-based maximal oxygen uptake (V̇O2max) test (SPV) has been shown to produce higher V̇O2max values than standard graded exercise test (GXT) protocols. This study sought to ascertain whether these observations would also be apparent in a self-paced, treadmill-based test design. Fourteen trained male runners performed a standard GXT on a motorised treadmill and a self-paced V̇O2max test on a nonmotorised treadmill in a counter-balanced design. The GXT included a plateau verification and was designed to last between 8 and 12 min. The self-paced test included 5 × 2 min stages and allowed participants to set their own running speed based on fixed increments in rating of perceived exertion. Significantly higher V̇O2max values (t[13] = 3.71, p = 0.003) were achieved in the self-paced test (64.4 ± 7.3 mL · kg(-1) · min(-1)) compared with the GXT (61.3 ± 7.3 mL · kg(-1) · min(-1)), and 13 of the 14 participants achieved the same or higher V̇O2max values in the self-paced test. Higher (p = 0.01) maximum heart rates were observed in the GXT (191 ± 10 beats · min(-1) vs. 187 ± 7 beats · min(-1)), but no differences were observed in any other recorded variables. The self-paced V̇O2max test may provide a more valid means of measuring V̇O2max than the GXT and suggests that a V̇O2 plateau during a GXT does not always signify achievement of a definitive V̇O2max. These results provide further support that self-paced V̇O2max testing produces higher values for maximal oxygen uptake.

Review of Kinemax total knee replacements performed at the NHS treatment centre, Weston-Super-Mare: five-year results

As part of the national initiative to reduce waiting times for joint replacement surgery in Wales, the Cardiff and Vale NHS Trust referred 224 patients to the NHS Treatment Centre in Weston-Super-Mare for total knee replacement (TKR). A total of 258 Kinemax TKRs were performed between November 2004 and August 2006. Of these, a total of 199 patients (232 TKRs, 90%) have been followed up for five years. This cohort was compared with 258 consecutive TKRs in 250 patients, performed at Cardiff and Vale Orthopaedic Centre (CAVOC) over a similar time period. The five year cumulative survival rate was 80.6% (95% confidence interval (CI) 74.0 to 86.0) in the Weston-Super-Mare cohort and 95.0% (95% CI 90.2 to 98.2) in the CAVOC cohort with revision for any reason as the endpoint. The relative risk for revision at Weston-Super-Mare compared with CAVOC was 3.88 (p < 0.001). For implants surviving five years, the mean Oxford knee scores (OKS) and mean EuroQol (EQ-5D) scores were similar (OKS: Weston-Super-Mare 29 (2 to 47) vs CAVOC 29.8 (3 to 48), p = 0.61; EQ-5D: Weston-Super-Mare 0.53 (-0.38 to 1.00) vs CAVOC 0.55 (-0.32 to 1.00), p = 0.79). Patients with revised TKRs had significantly lower Oxford knee and EQ-5D scores (p < 0.001). The results show a higher revision rate for patients operated at Weston-Super-Mare Treatment Centre, with a reduction in functional outcome and quality of life after revision. This further confirms that patients moved from one area to another for joint replacement surgery fare poorly.

Conventional testing methods produce submaximal values of maximum oxygen consumption

BACKGROUND

This study used a novel protocol to test the hypothesis that a plateau in oxygen consumption (VO(2 max)) during incremental exercise testing to exhaustion represents the maximal capacity of the cardiovascular system to transport oxygen.

METHODS

Twenty-six subjects were randomly divided into two groups matched by their initial VO(2 max). On separate days, the reverse group performed (i) an incremental uphill running test on a treadmill (INC(1)) plus verification test (VER) at a constant workload 1 km h(-1) higher than the last completed stage in INC(1); (ii) a decremental test (DEC) in which speed started as same as the VER but was reduced progressively and (iii) a final incremental test (INC(F)). The control group performed only INC on the same days that the reverse group was tested.

RESULTS

VO(2 max) remained within 0.6 ml kg(-1) min(-1) across the three trials for the control group (p=0.93) but was 4.4% higher during DEC compared with INC(1) (63.9 ± 3.8 vs 61.2 ± 4.8 ml kg(-1) min(-1), respectively, p=0.004) in the reverse group, even though speed at VO(2 max) was lower (14.3 ± 1.1 vs 16.2 ± 0.7 km h(-1) for DEC and INC(1), respectively, p=0.0001). VO(2 max) remained significantly higher during INC(F) (63.6 ± 3.68 ml kg(-1) min(-1), p=0.01), despite an unchanged exercise time between INC(1) and INC(F).

CONCLUSION

These findings go against the concept that a plateau in oxygen consumption measured during the classically described INC and VER represents a systemic limitation to oxygen use. The reasons for a higher VO(2) during INC(F) following the DEC test are unclear.

Haemorrhage control in pelvic fractures--a survey of surgical capabilities

BACKGROUND

In the emergency management of patients with pelvic fractures, there is ongoing debate about the roles of angiography and open pelvic packing. It is agreed that some form of haemorrhage control is required for patients who are haemo-dynamically unstable despite resuscitation. We set out to determine whether on-call general and orthopaedic surgeons would feel able to perform emergency surgical procedures for these patients and whether vascular radiology was available to them.

METHODS

Surveys were sent to all 221 general and orthopaedic surgeons in Wales. Questions included: sub-speciality interest, geographical region, whether there is a pelvic binder in their hospital, availability of interventional radiology, and whether surgeons would perform a range of procedures to control haemorrhage in the emergency setting.

RESULTS

There were 141 responses to the survey, giving a 64% response rate. Only 18% reported that their unit had a formal rota for interventional radiology out of hours. 16% did not know. 96% of orthopaedic surgeons would perform external fixation, although only 49% would use a C-clamp. 90% of general surgeons would be able to pack the pelvis from within the abdominal compartment and 84% would be prepared to cross-clamp the aorta if the situation required. Despite being widely recommended in the literature as a method of haemorrhage control, our survey revealed only 45% would perform extra(pre)-peritoneal packing of the pelvis (58% of general surgeons; 34% of orthopaedic surgeons) and only 12% had received formal training in this procedure.

CONCLUSIONS

With appropriately targeted training it is likely that the care of patients with pelvic fractures can be significantly improved.

Performance monitoring in hip fracture surgery--how big a database do we really need?

Systems for collecting information about patient care are increasingly common in orthopaedic practice. Databases can allow various comparisons to be made over time. Significant decisions regarding service delivery and clinical practice may be made based on their results. We set out to determine the number of cases needed for comparison of 30-day mortality, inpatient wound infection rates and mean hospital length of stay, with a power of 80% for the demonstration of an effect at a significance level of p<0.05. We analysed 2 years of prospectively collected data on 1050 hip fracture patients admitted to a city teaching hospital. Detection of a 10% difference in 30-day mortality would require 14,065 patients in each arm of any comparison, demonstration of a 50% difference would require 643 patients in each arm; for wound infections, demonstration of a 10% difference in incidence would require 23,921 patients in each arm and 1127 patients for demonstration of a 50% difference; for length of stay, a difference of 10% would require 1479 patients and 6660 patients for a 50% difference. This study demonstrates the importance of considering the population sizes before comparisons are made on the basis of basic hip fracture outcome data. Our data also help illustrate the impact of sample size considerations when interpreting the results of performance monitoring. Many researchers will be used to the fact that rare outcomes such as inpatient mortality or wound infection require large sample sizes before differences can be reliably demonstrated between populations. This study gives actual figures that researchers could use when planning studies. Statistically meaningful analyses will only be possible with major multi-centre collaborations, as will be possible if hospital Trusts participate in the National Hip Fracture Database.

Techniques for improving stability in oblique fractures treated by circular fixation with particular reference to the sagittal plane

Biomechanical studies involving all-wire and hybrid types of circular frame have shown that oblique tibial fractures remain unstable when they are loaded. We have assessed a range of techniques for enhancing the fixation of these fractures. Eight models were constructed using Sawbones tibiae and standard Sheffield ring fixators, to which six additional fixation techniques were applied sequentially. The major component of displacement was shear along the obliquity of the fracture. This was the most sensitive to any change in the method of fixation. All additional fixation systems were found to reduce shear movement significantly, the most effective being push-pull wires and arched wires with a three-hole bend. Less effective systems included an additional half pin and arched wires with a shallower arc. Angled pins were more effective at reducing shear than transverse pins. The choice of additional fixation should be made after consideration of both the amount of stability required and the practicalities of applying the method to a particular fracture.