Bomb blast imaging: bringing order to chaos.

Blast injuries are complex, severe, and outside of our everyday clinical practice, but every radiologist needs to understand them. By their nature, bomb blasts are unpredictable and affect multiple victims, yet require an immediate, coordinated, and whole-hearted response from all members of the clinical team, including all radiology staff. This article will help you gain the requisite expertise in blast imaging including recognising primary, secondary, and tertiary blast injuries. It will also help you understand the fundamental role that imaging plays during mass casualty attacks and how to avoid radiology becoming a bottleneck to the forward flow of severely injured patients as they are triaged and treated.

The epidemiology and functional outcomes of operative fixation of extracapsular proximal femoral fractures (AO 31-A) in young adults.

Proximal femoral fractures in adults under 50 years are not as common as in the elderly, but may have just as significant an impact. There is little in the literature describing the functional outcomes of fixation in this age group. Our aim was to assess the clinical and functional outcomes of operative management of extracapsular proximal femoral fractures (AO 31-A) in the young adult (<50 years). Consecutive skeletally mature patients <50 years undergoing operative fixation of these fractures were obtained from a prospective database over a 12-year period. Complications and mortality data were obtained from this database and case note review. Outcome scores were obtained via postal questionnaires. Eighty-eight patients were included in the study of which 74 (84%) had fixation with the dynamic hip screw. The mean age was 39 years (range 17-50) with a male preponderance (73.8%). Mean hospital stay was 14 days (range 2-94). Seventeen (19.3%) patients had died at a mean of 40 months from their operation date. The 1-year mortality was 4.5%. There were five complications (5.7%). SF-36 and EuroQol 5D scores showed that 5-10% had severe problems with a 20% decrease in quality of life compared to population norms. The biggest differences were in the physical function modalities. One-third had fair to poor hip function as assessed by the Oxford Hip Score. Though these injuries are relatively rare in this age group, they do have significant mortality and functional impairment reflecting a higher energy of injury rather than the frailty seen in the elderly.

LiDCO-based fluid management in patients undergoing hip fracture surgery under spinal anaesthesia: a randomized trial and systematic review.

BACKGROUND: Hip fracture is a condition with high mortality and morbidity in elderly frail patients. Intraoperative fluid optimization may be associated with benefit in this population. We investigated whether intraoperative fluid management using pulse-contour analysis cardiac monitoring, compared with standard care in patients undergoing spinal anaesthesia, would provide benefits in terms of reduced time until medically fit for discharge and postoperative complications. METHODS: Patients undergoing surgical repair of fractured neck of femur, aged >60 yr, receiving spinal anaesthesia were enrolled in this single-centre, blinded, randomized, parallel group trial. Patients were allocated to either anaesthetist-directed fluid therapy or a pulse-contour-guided fluid optimization strategy using colloid (Gelofusine) boluses to optimize stroke volume. The primary outcome was time until medically fit for discharge. Secondary outcomes included postoperative complications, mobility, and mortality. We updated a systematic review to include relevant trials to 2014. RESULTS: We recruited 130 patients. Time until medically fit for discharge was similar in both groups, mean [95% confidence interval (CI)] 12.2 (11.1-13.5) vs 13.1 (11.9-14.5) days (P=0.31), as was total length of stay 14.2 (12.9-15.8) vs 15.3 (13.8-17.2) days (P=0.32). There were no significant differences in complications, function, or mortality. An updated meta-analysis (four studies, 355 patients) found non-significant reduction in early mortality [relative risk 0.66 (0.24-1.79)] and in-hospital complications [relative risk 0.80 (0.61-1.05)]. CONCLUSIONS: Goal-directed fluid therapy during hip fracture repair under spinal anaesthesia does not result in a significant reduction in length of stay or postoperative complications. There is insufficient evidence to either support or discount its routine use. CLINICAL TRIAL REGISTRATION: ISRCTN88284896.

Early management of the severely injured major trauma patient.

The major trauma team relies on an efficient, communicative team to ensure patients receive the best quality care. This requires a comprehensive handover, rapid systematic review, and early management of life- and limb-threatening injuries. These multiple injured patients often present with complex conditions in a dynamic situation. The importance of team work, communication, senior decision-making, and documentation cannot be underestimated.

The direct cost of acute hip fracture care in care home residents in the UK.

UNLABELLED: Data on the true acute care costs of hip fractures for patients admitted from care homes are limited. Detailed costing analysis was undertaken for 100 patients. Median cost was £9,429 [10,896], increasing to £14,435 [16,681], for those requiring an upgrade from residential to nursing home care. Seventy-six percent of costs were attributable to hospital bed days, and therefore, interventions targeted at reducing hospital stay may be cost effective. INTRODUCTION: Previous studies have estimated the costs associated with hip fracture, although these vary widely, and for patients admitted from care homes, who represent a significant fracture burden, there are limited data. The primary aim of this study was to perform a detailed assessment of the direct medical costs incurred and secondly compare this to the actual remuneration received by the hospital. METHODS: One hundred patients presenting from a care home in 2006 were randomly selected and a detailed case-note costing analysis was undertaken. This cost was then compared to the actual remuneration received by the hospital. RESULTS: Median cost per patient episode was £9,429 [10,896] (all patients) range £4,292-162,324 [4,960-187,582] (subdivided into hospital bed day costs £7,129 [8,238], operative costs £1,323 [1,529] and investigation costs £977 [1,129]). Twenty-two percent of the patients admitted from a residential home required upgrading to a nursing home. In this group, the median length of stay was 31 days (mean 38, range 10-88) median cost £14,435 [16,681]. Average remuneration received equated to £6,222 [7,190] per patient. This represents a mean loss in income, compared to actual calculated costs of £3,207 [3,706] per patient. CONCLUSION: The median cost was £9,429 [10,896], increasing to £14,435 [16,681], for those requiring an upgrade from residential to nursing home care at discharge. Significant cost differences were seen comparing the actual cost to remuneration received. Interventions targeted at reducing length of stay may be cost effective.

Nottingham Hip Fracture Score: longitudinal and multi-assessment.

BACKGROUND: The Nottingham Hip Fracture Score (NHFS) was developed and validated in a single centre in 2007 as a predictor of 30 day mortality. It has subsequently been shown to predict longer term and functional outcomes. We wished to assess the ability of NHFS to predict outcomes in other centres and to investigate the change in outcome after hip fracture over time. METHODS: The NHFS was calculated for all patients with data from three UK hip fracture units: Peterborough (1992-2009), Brighton (2008-9), and Nottingham (2000-9) including 4804, 585, and 1901 patients, respectively. The logistic regression was used to recalibrate the NHFS to 30 day mortality across the three units using a random selection of 50% of the data set. Calibration was assessed using the Hosmer-Lemeshow goodness of fit. RESULTS: The median (inter-quartile range) NHFS values were Peterborough [4.0 (1-6)], Brighton [5.0 (3-7)], and Nottingham [5.0 (3-7)]. There was no correlation between 30 day mortality and time (R(2)=0.05, P=0.115). The proportion of patients with NHFS ≥ 4 showed a weak correlation with time (R(2)=0.2, P=0.003). The original NHFS equation overestimates mortality in the higher-risk groups. A modified equation shows good calibration for all three centres {30 day mortality (%)=100/1+e([(5.012 × (NHFS × 0.481)])}. The hospital was not a predictor of 30 day mortality. CONCLUSIONS: The NHFS, with an updated equation, is a robust predictor of 30 day mortality after hip fracture repair in geographically distinct UK centres.

Nottingham Hip Fracture Score as a predictor of one year mortality in patients undergoing surgical repair of fractured neck of femur.

BACKGROUND: Surgical repair of hip fractures is associated with high postoperative mortality. The identification of high-risk patients might be of value in aiding clinical management decisions and resource allocation. The Nottingham Hip Fracture Score (NHFS) is a scoring system validated for the prediction of 30 day mortality after hip fracture surgery. It is made up of seven independent predictors of mortality that have been incorporated into a risk score: age (66-85 and ≥86 yr); sex (male); number of co-morbidities (≥2), admission mini-mental test score (≤6 out of 10), admission haemoglobin concentration (≤10 g dl(-1)), living in an institution; and the presence of malignancy. We investigated whether the NHFS was a predictor of 1 yr mortality in patients undergoing surgical repair of fractured neck of femur. METHODS: NHFS was retrospectively calculated for 6202 patients who had undergone hip fracture surgery between 1999 and 2009. One year and 30 day postoperative mortality data were collected both from hospital statistics and the Office of National Statistics. RESULTS: Overall mortality was 8.3% at 30 days and 29.3% at 1 yr. An NHFS of ≤4 was considered low risk and a score of ≥5 high risk. Survival was greater in the low-risk group at 30 days [96.5% vs 86.3% (P<0.001)] and at 1 yr [84.1% vs 54.5% (P<0.001)]. CONCLUSIONS: NHFS can be used to stratify the risk of 1 yr mortality after hip fracture surgery.

Time to definitive care within major trauma networks in England.

BACKGROUND: Significant mortality improvements have been reported following the implementation of English trauma networks. Timely transfer of seriously injured patients to definitive care is a key indicator of trauma network performance. This study evaluated timelines from emergency service (EMS) activation to definitive care between 2013 and 2016. METHODS: An observational study was conducted on data collected from the UK national clinical audit of major trauma care of patients with an Injury Severity Score above 15. Outcomes included time from EMS activation to: arrival at a trauma unit (TU) or major trauma centre (MTC); to CT; to urgent surgery; and to death. RESULTS: Secondary transfer was associated with increased time to urgent surgery (median 7·23 (i.q.r. 5·48-9·28) h versus 4·37 (3·00-6·57) h for direct transfer to MTC; P < 0·001) and an increased crude mortality rate (19·6 (95 per cent c.i. 16·9 to 22·3) versus 15·7 (14·7 to 16·7) per cent respectively). CT and urgent surgery were performed more quickly in MTCs than in TUs (2·00 (i.q.r. 1·55-2·73) versus 3·15 (2·17-4·63) h and 4·37 (3·00-6·57) versus 5·37 (3·50-7·65) h respectively; P < 0·001). Transfer time and time to CT increased between 2013 and 2016 (P < 0·001). Transfer time, time to CT, and time to urgent surgery varied significantly between regional networks (P < 0·001). CONCLUSION: Secondary transfer was associated with significantly delayed imaging, delayed surgery, and increased mortality. Key interventions were performed more quickly in MTCs than in TUs.

ANTECEDENTES: Se han demostrado mejoras significativas en la mortalidad tras la implementación de las redes de trauma en Inglaterra. El traslado a tiempo de pacientes con lesiones graves para el tratamiento definitivo es un indicador clave del rendimiento de la red de traumatismos. Este estudio evaluó los plazos de tiempo desde la activación del servicio de emergencia (emergency service,EMS) hasta el tratamiento definitivo entre 2013 y 2016. MÉTODOS: Se realizó un estudio observacional en base a los datos obtenidos de la auditoría clínica nacional del Reino Unido de la atención de traumatismos graves en pacientes con puntuación de gravedad de lesiones superior a 15. Los resultados incluyeron los intervalos de tiempo entre la activación del EMS hasta la llegada a una Unidad de Trauma (Trauma Unit, TU) o a un centro de traumatismos graves (Major Trauma Center, MTC), la práctica de una tomografía computarizada (computerised tomography, CT), la práctica de cirugía de urgencia, y la mortalidad. RESULTADOS: El traslado secundario se asoció con un aumento en el tiempo hasta la cirugía urgente (7,23 h (rango intercuartílico, RIQ 5,48-9,28 versus 4,37 (3,00-6,57), P < 0,001)) y un aumento de la mortalidad cruda (19,6% (i.c. del 95% 16,9-22,3) versus 15,7% (14,7-16,7)). La CT y la cirugía urgente se efectuaron con mayor rapidez en los centros MTC que TU (2,00 h (RIQ 1,55-2,73) versus 3,15 h (RIQ 2,17-4,63) y 4,37 h (RIQ 3,00-6,57) versus 5,37 h (RIQ 3,50-7,65), respectivamente (P < 0,001)). El tiempo de traslado y el tiempo hasta la práctica de la CT aumentaron entre 2013 y 2016 (P < 0,001). El tiempo de traslado, el tiempo hasta la práctica de la CT y el tiempo hasta la práctica de cirugía urgente variaron significativamente entre las redes regionales (P < 0,001). CONCLUSIÓN: El traslado secundario se asoció de forma significativa con el retraso en las imágenes radiológicas, retraso en la cirugía y aumento de la mortalidad. Las intervenciones clave se realizaron más rápidamente en centro MTC que en centros TU.

Open tibial fractures in major trauma centres: A national prospective cohort study of current practice.

AIMS: To assess current national practice in the management of severe open tibial fractures against national standards, using data collected by the Trauma and Audit Research Network. MATERIALS AND METHODS: Demographic, injury-specific, and outcome data were obtained for all grade IIIB/C fractures admitted to Major Trauma Centres in England from October 2014 to January 2016. RESULTS: Data was available for 646 patients with recorded grade IIIB/C fractures. The male to female ratio was 2.3:1, mean age 47 years. 77% received antibiotics within 3 h of admission, 82% were debrided within 24 h. Soft tissue coverage was achieved within 72 h of admission in 71%. The amputation rate was 8.7%. 4.3% of patients required further theatre visits for infection during the index admission. The timing of antibiotics and surgery could not be correlated with returns to theatre for early infection. There were significant differences in the management and outcomes of patients aged 65 and over, with an increase in mortality and amputation rates. CONCLUSIONS: Good outcomes are reported from the management of IIIB/C fractures in Major Trauma Centres in England. Overall compliance with national standards is particularly poor in the elderly. Compliance did not appear to affect rates of returning to theatre or early infection. Appropriately applied patient reported outcome measures are needed to enhance the evidence-base for management of these injuries.

Development and validation of a preoperative scoring system to predict 30 day mortality in patients undergoing hip fracture surgery.

BACKGROUND: Hip fractures are common in the elderly and have a high 30 day postoperative mortality. The ability to recognize patients at high risk of poor outcomes before operation would be an important clinical advance. This study has determined key prognostic factors predicting 30 day mortality in a hip fracture population, and incorporated them into a scoring system to be used on admission. METHODS: A cohort study was conducted at the Queen's Medical Centre, Nottingham, over a period of 7 yr. Complete data were collected from 4967 patients and analysed. Forward univariate logistic regression was used to select the independent predictor variables of 30 day mortality, and then multivariate logistic regression was applied to the data to construct and validate the scoring system. RESULTS: The variables found to be independent predictors of mortality at 30 days were: age (66-85 yr, > or =86 yr), sex (male), number of co-morbidities (> or =2), mini-mental test score (< or =6 out of 10), admission haemoglobin concentration (< or =10 g dl(-1)), living in an institution, and presence of malignant disease. These variables were subsequently incorporated into a risk score, the Nottingham Hip Fracture Score. The number of deaths observed at 30 days, and the number of deaths predicted by the scoring system, indicated good concordance (chi(2) test, P=0.79). The area (SE) under the receiver operating characteristic curve was 0.719 (0.018), which demonstrated a reasonable predictive value for the score. CONCLUSIONS: We have developed and validated a scoring system that reliably predicts the probability of mortality at 30 days for patients after hip fracture.

Early infection after hip fracture surgery: risk factors, costs and outcome.

Prospective data on hip fracture from 3686 patients at a United Kingdom teaching hospital were analysed to investigate the risk factors, financial costs and outcomes associated with deep or superficial wound infections after hip fracture surgery. In 1.2% (41) of patients a deep wound infection developed, and 1.1% (39) had a superficial wound infection. A total of 57 of 80 infections (71.3%) were due to Staphylococcus aureus and 39 (48.8%) were due to MRSA. No statistically significant pre-operative risk factors were detected. Length of stay, cost of treatment and pre-discharge mortality all significantly increased with deep wound infection. The one-year mortality was 30%, and this increased to 50% in those who developed an infection (p < 0.001). A deep infection resulted in doubled operative costs, tripled investigation costs and quadrupled ward costs. MRSA infection increased costs, length of stay, and pre-discharge mortality compared with non-MRSA infection.

Does achieving the best practice tariff improve outcomes in hip fracture patients? An observational cohort study.

OBJECTIVES: To determine if the introduction of the best practice tariff (BPT) has improved survival of the elderly hip fracture population, or if achieving BPT results in improved survival for an individual. SETTING: A single university-affiliated teaching hospital. PARTICIPANTS: 2541 patients aged over 60 admitted with a neck of femur fracture between 2008 and 2010 and from 2012 to 2014 were included, to create two cohorts of patients, before and after the introduction of BPT. The post-BPT cohort was divided into two groups, those who achieved the criteria and those who did not. PRIMARY AND SECONDARY OUTCOME MEASURES: Primary outcomes of interest were differences in mortality across cohorts. Secondary analysis was performed to identify associations between individual BPT criteria and mortality. RESULTS: The introduction of BPT did not significantly alter overall 30-mortality in the hip fracture population (8.3% pre-BPT vs 10.0% post-BPT; p=0.128). Neither was there a significant reduction in length of stay (15 days (IQR 9-21) pre-BPT vs 14 days (IQR 11-22); p=0.236). However, the introduction of BPT was associated with a reduction in the time from admission to theatre (median 44 hours pre-BPT (IQR 24-44) vs 23 hours post-BPT (IQR 17-30); p<0.005). 30-day mortality in those who achieved BPT was significantly lower (6.0% vs 21.0% in those who did not achieve-BPT; p<0.005). There was a survival benefit at 1 year for those who achieved BPT (28.6% vs 42.0% did not achieve-BPT; p<0.005). Multivariate logistic regression revealed that of the BPT criteria, AMT monitoring and expedited surgery were the only BPT criteria that significantly influenced survival. CONCLUSIONS: The introduction of the BPT has not led to a demonstrable improvement in outcomes at organisational level, though other factors may have confounded any benefits. However, patients where BPT criteria are met appear to have improved outcomes.

The effect of surgical experience on the amount of radiation exposure from fluoroscopy during dynamic hip screw fixation.

INTRODUCTION Dynamic hip screw (DHS) fixation for proximal femur fractures is one of the most common procedures in trauma that requires the use of fluoroscopy. Emphasis is often placed on producing the 'perfect picture', which may lead to excessive use of fluoroscopy, without added patient benefit. This study, the largest of its kind, aimed to determine the effect of surgical experience on the amount of radiation exposure from fluoroscopy during DHS fixation. METHODS All hospital admissions for extracapsular proximal femur fractures to our institution between 2007 and 2012 were analysed. Patient demographics, fracture configuration, grade of surgeon and the total radiation dose after fixation were recorded. Analysis of variance was performed to assess differences in radiation levels between different grades of surgeon. RESULTS A total of 1,203 patients with a mean age of 81.3 years (range: 21-105 years) were included in the study. The majority of the fractures were three-part (33.3%), followed by two-part (32.2%), four-part (25.7%) and basicervical (8.9%). Registrars (ST3-ST8) used a significantly higher radiation dose than consultants for all fracture types (p=0.009). When analysed separately by trainee group, the most junior registrars (ST3-ST4) and the most senior registrars (ST7-ST8) were found to use significantly higher radiation levels than consultants (p=0.037 and p<0.001 respectively). CONCLUSIONS The level of surgical experience does influence the amount of radiation exposure from fluoroscopy during DHS fixation. Surgical trainees should not ignore the potential harmful effects of radiation and should be equipped with the knowledge of how to keep the radiation exposure as low as possible.

Predictors of direct home discharge following fractured neck of femur.

INTRODUCTION Direct home discharge (DHD) following hip fracture surgery represents a challenging proposition. The aim of this study was to identify factors influencing the discharge destination (home vs alternative location) for patients admitted from their own home with a fractured neck of femur. METHODS A retrospective cohort study of prospectively collected major trauma centre data was performed, identifying 10,044 consecutive hip fracture admissions between 2000 and 2012. RESULTS Two-thirds of the patients (n=6,742, 67%) were admitted from their own home. Half of these (n=3,509, 52%) returned directly to their own home while two-fifths (n=2,640, 39%) were discharged to an alternative location; 593 (9%) died. The following were identified as independent variables associated with a higher likelihood of DHD: younger patients, female sex, an abbreviated mental test score of 10, absence of certain co-morbidities, cohabiting, walking independently outdoors, no use of walking aids, no assistance required with basic activities of daily living and intracapsular fracture. CONCLUSIONS Identifying those at risk of being discharged to an alternative location following admission from home on the basis of identified preoperative indices could assist in streamlining the postoperative care phase. Pre-emptive action may help increase the numbers of patients discharged directly home and reduce the number requiring additional rehabilitation prior to discharge home with its associated socioeconomic effect.

A unified theory of bone healing and nonunion: BHN theory.

This article presents a unified clinical theory that links established facts about the physiology of bone and homeostasis, with those involved in the healing of fractures and the development of nonunion. The key to this theory is the concept that the tissue that forms in and around a fracture should be considered a specific functional entity. This 'bone-healing unit' produces a physiological response to its biological and mechanical environment, which leads to the normal healing of bone. This tissue responds to mechanical forces and functions according to Wolff's law, Perren's strain theory and Frost's concept of the "mechanostat". In response to the local mechanical environment, the bone-healing unit normally changes with time, producing different tissues that can tolerate various levels of strain. The normal result is the formation of bone that bridges the fracture - healing by callus. Nonunion occurs when the bone-healing unit fails either due to mechanical or biological problems or a combination of both. In clinical practice, the majority of nonunions are due to mechanical problems with instability, resulting in too much strain at the fracture site. In most nonunions, there is an intact bone-healing unit. We suggest that this maintains its biological potential to heal, but fails to function due to the mechanical conditions. The theory predicts the healing pattern of multifragmentary fractures and the observed morphological characteristics of different nonunions. It suggests that the majority of nonunions will heal if the correct mechanical environment is produced by surgery, without the need for biological adjuncts such as autologous bone graft. Cite this article: Bone Joint J 2016;98-B:884-91.

Failure of perfusion with oxygenated Krebs-Ringer solution to preserve the eccrine function of the vascular endothelium in bone.

An ex vivo canine tibia preparation was perfused at a constant rate with aerated (95% O2-5% CO2) Krebs-Ringer solution for 24 h. Bolus injections of norepinephrine (0.125-0.5 micrograms) were given and then acetylcholine (5 x 10(-5) M) was used to stimulate endothelial production of smooth muscle relaxing factors. Following 1 h of perfusion the addition of acetylcholine resulted in significant attenuation of the response to norepinephrine (p < 0.001). After 4 h perfusion acetylcholine did not attenuate the norepinephrine response, but addition of L-arginine (the precursor of endothelial-derived relaxing factor) resulted in significant attenuation in the presence of acetylcholine (p < 0.005). At 6, 12, and 24 h the acetylcholine did not attenuate the norepinephrine response. It is concluded that normothermic, continuous perfusion with oxygenated Krebs-Ringer solution results in normal endothelial eccrine activity up to 1 h. Following this period there is substrate depletion but endothelial eccrine function can be demonstrated for up to 4 h. At 6 h this function cannot be demonstrated, suggesting degradation of the functional integrity of the endothelium.

Adrenergic control mechanisms of blood flow in a vascularized canine tibial allograft.

A vascularized canine tibial allograft was used to study the alpha-adrenoreceptor subtypes of the microcirculation of bone. Bone transplantation was performed on six dogs, and the bone blood flow was estimated with the use of serial injections of radiolabeled 15 microns microspheres. After microvascular anastomosis, the mean cortical blood flow in the allografted tibia was 3.6 +/- 2.1 ml/100 g/min. Alpha 1-adrenoreceptor blockade, with prazosin, caused an increase in normalized blood flow in five allografts and a slight decrease in one allograft. The mean increase was 32 +/- 48%, but this was not statistically significant (p < 0.2). The addition of an alpha 2-adrenoreceptor blockade, with rauwolszin, resulted in a significant increase (132 +/- 88%) in normalized blood flow in all allografts (p < 0.02). This ex vivo experiment confirms that both alpha 1 and alpha 2 adrenergic mechanisms play a role in controlling bone blood flow in centrally denervated allografts.

Preservation of bone graft vascularity with the University of Wisconsin cold storage solution.

The preservation of the microcirculation of bone has been evaluated with use of an in vitro canine tibia perfusion model. The production of relaxing factors by the osseous vascular endothelium was used as a metabolic marker for viability. This endothelial eccrine function was preserved for 5 days (120 h) by cold storage without continuous perfusion after a washout with the University of Wisconsin (UW) solution. This synthetic perfusate was superior to Krebs Ringer solution (p < 0.05), but storage without perfusion failed to prevent a significant rise in vascular resistance. Two techniques were effective for the preservation of bone vascularity for 24 h: washout with UW solution followed by nonperfusion cold (4 degrees C) storage, and vascular washout with mannitol solution followed by continuous hypothermic (5 degrees C) microperfusion (0.03 ml/min) with UW solution. The most consistent, and lowest, vascular resistance was produced by the microperfusion technique. However, UW solution does not consistently prevent an increase in vascular resistance with hypothermic ischemia. This technique may prove useful for the preservation of vascularized bone grafts, but it needs to be evaluated in a transplantation model.