Critical care usage after major gastrointestinal and liver surgery: a prospective, multicentre observational study

BACKGROUND

Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery.

METHODS

This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and inter-centre variation in critical care admission after emergency laparotomy.

RESULTS

Of 4529 patients included, 37.8% (n=1713) underwent planned critical care admissions from theatre. Some 3.1% (n=86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n=133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51-19.97) than planned admissions (OR: 2.32, 95% CI: 1.43-3.85). Some 26.7% of patients (n=1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8-51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n=10/145) of centres outside the 95% CI.

CONCLUSIONS

After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies.

Development of mapped stress-field boundary conditions based on a Hill-type muscle model

Forces generated in the muscles and tendons actuate the movement of the skeleton. Accurate estimation and application of these musculotendon forces in a continuum model is not a trivial matter. Frequently, musculotendon attachments are approximated as point forces; however, accurate estimation of local mechanics requires a more realistic application of musculotendon forces. This paper describes the development of mapped Hill-type muscle models as boundary conditions for a finite volume model of the hip joint, where the calculated muscle fibres map continuously between attachment sites. The applied muscle forces are calculated using active Hill-type models, where input electromyography signals are determined from gait analysis. Realistic muscle attachment sites are determined directly from tomography images. The mapped muscle boundary conditions, implemented in a finite volume structural OpenFOAM (ESI-OpenCFD, Bracknell, UK) solver, are employed to simulate the mid-stance phase of gait using a patient-specific natural hip joint, and a comparison is performed with the standard point load muscle approach. It is concluded that physiological joint loading is not accurately represented by simplistic muscle point loading conditions; however, when contact pressures are of sole interest, simplifying assumptions with regard to muscular forces may be valid.

Development of a Hip Joint Model for Finite Volume Simulations

This paper establishes a procedure for numerical analysis of a hip joint using the finite volume method. Patient-specific hip joint geometry is segmented directly from computed tomography and magnetic resonance imaging datasets and the resulting bone surfaces are processed into a form suitable for volume meshing. A high resolution continuum tetrahedral mesh has been generated, where a sandwich model approach is adopted; the bones are represented as a stiffer cortical shells surrounding more flexible cancellous cores. Cartilage is included as a uniform thickness extruded layer and the effect of layer thickness is investigated. To realistically position the bones, gait analysis has been performed giving the 3D positions of the bones for the full gait cycle. Three phases of the gait cycle are examined using a finite volume based custom structural contact solver implemented in open-source software OpenFOAM.

Automated In-Vitro Testing of Orthopaedic Implants: A Case Study in Shoulder Joint Replacement

This investigation presents the design and preliminary validation of a single station simulator with biaxial motion and loading designed to mimic the kinematics of the glenohumeral joint during arm abduction in the scapular plane. Although the design of the glenoid holder allows the glenoid component to translate in all three axes, it is primarily loaded axially, which brings it into contact with the oscillating humeral head, but is also loaded superiorly to simulate common subluxation of the humeral head. Simulating arm abduction in the scapular plane simplifies component alignment and removes the need for anterior—posterior loading, thereby creating a stable joint without the need to simulate capsular constraints. In this more physiologically accurate simulator design, the load and motion profiles influence the contact kinematics, but the wear path is ultimately determined by the conformity and constraint designed into the bearing couple. The wear data are determined and correlated with clinically retrieved glenoid components, as well as previously reported in-vitro studies, thus verifying use of the simulator in testing alternative materials and designs. The key design features, as well as the improvements proposed through this study, can be incorporated into the design of test fixtures for any other orthopaedic implant such as the hip, knee, spine, elbow, and finger.

A finite-element analysis study of the metatarsophalangeal joint of the hallux rigidus

Hallux rigidus was first described in 1887. Many aetiological factors have been postulated, but none has been supported by scientific evidence. We have examined the static and dynamic imbalances in the first metatarsophalangeal joint which we postulated could be the cause of this condition. We performed a finite-element analysis study on a male subject and calculated a mathematical model of the joint when subjected to both normal and abnormal physiological loads.

The results gave statistically significant evidence for an increase in tension of the plantar fascia as the cause of abnormal stress on the articular cartilage rather than mismatch of the articular surfaces or subclinical muscle contractures. Our study indicated a clinical potential cause of hallux rigidus and challenged the many aetiological theories. It could influence the choice of surgical procedure for the treatment of early grades of hallux rigidus.

Folate and Clefts of the Lip and Palate—A U.K.-Based Case-Control Study: Part I: Dietary and Supplemental Folate

Objectives:

We sought to determine the associations between nonsyndromic cleft lip with or without cleft palate (CL−P) and cleft palate only (CP) and maternal intake of dietary folate and supplemental folic acid, in an area where the prevalence at birth of neural tube defects has been high and flour is not fortified with folic acid.

Methods:

Interviews regarding periconceptional dietary intake and supplement use were completed with the mothers of 112 CL−P cases, 78 CP cases, and 248 unaffected infants. The data were analyzed by logistic regression methods.

Results:

There was no overall association between CL−P and CP and either energy-adjusted total folate intake or supplemental folic acid use, irrespective of dosage.

Conclusion:

Overall, higher intakes of total folate do not appear to prevent oral clefts in this population.

Folate and Clefts of the Lip and Palate—A U.K.-Based Case-Control Study: Part II: Biochemical and Genetic Analysis

Objective:

To investigate associations between nonsyndromic oral clefts and biochemical measures of folate status and the MTHFR C677T variant in the United Kingdom, where there has been no folic acid fortification program.

Method:

Dietary details were obtained from the mothers of 112 cases of cleft lip with or without cleft palate (CL±P), 78 cleft palate only (CP) cases, and 248 unaffected infants. Infant and parental MTHFR C677T genotype was determined. Red blood cell (RBC) and serum folate and homocysteine levels were assessed in 12-month postpartum blood samples from a subset of mothers. The data were analyzed by logistic and log-linear regression methods.

Results:

There was an inverse association between CL±P and maternal MTHFR CT (odds ratio [OR]  =  0.5, 95% confidence interval [CI]  =  0.31–0.95) and TT (OR  =  0.6, 95% CI  =  0.21–1.50) genotypes, with similar risk estimates for CP. There was no clear association with infant MTHFR genotype. Higher levels of maternal postpartum RBC and serum folate were associated with a lower risk for CL±P and an increased risk for CP. Higher levels of serum homocysteine were associated with a slightly increased risk for both CL±P and CP.

Conclusion:

While the inverse relation between the mother's having the MTHFR C677T variant and both CL±P and CP suggests perturbation of maternal folate metabolism is of etiological importance, contrasting relations between maternal postpartum levels of RBC and serum folate by type of cleft are difficult to explain.

Tibiofemoral cartilage thickness distribution and its correlation with anthropometric variables

The objective of this study was to determine tibiofemoral cartilage thickness distribution, and to investigate the relationship between cartilage geometry and anthropometric variables. In this study, 20 magnetic resonance examinations of the knee from normal individuals were reconstructed to provide three-dimensional models of the knee joint, including bony and cartilage surfaces. Three regions were defined on the articular surface, and the cartilage thickness distribution along each of these was determined. Statistically significant differences between femoral and tibial regions were examined using the paired Student t test in Microsoft Excel. Correlations were investigated using the correlation tool in Microsoft Excel. The average tibial cartilage thickness was found to be 2.76 mm and the average femoral cartilage thickness was 2.75 mm. Significant correlations exist between the tibia cartilage thickness and body height (R = 0.60; P < 0.05) and weight (R = 0.64; P < 0.05). Significant correlations exist between the femoral cartilage volume and the body height (R = 0.736; P < 0.01) and weight (R = 0.855; P < 0.01). It is suggested that the distribution and correlations of cartilage distribution indicate adaptation in response to mechanical loading. Information regarding cartilage thickness and volume distribution as found in this study may be useful in diagnosing and monitoring cartilage loss in patients with degenerative joint disease.

Quantification of the coupled motion that occurs with axial rotation and lateral bending of the head-neck complex: an experimental examination

The vertebrae of the cervical spine exhibit out-of-plane or coupled motion during axial rotation and lateral bending. Quantifying the range of motion (ROM) of this occurrence can aid the understanding of cervical spine injury mechanisms and disorders, as well as the development of new treatment methods. Previous studies have formulated ratios to describe coupled motion obtained from in-vitro examinations. The aim of the present study was to use in-vivo test data to develop mathematical relationships to quantify the coupled motion that occurs with axial rotation and lateral bending of the head-neck complex. Using a three-dimensional motion analyser it was possible to trace the coupling effect throughout the full range of unrestricted head-neck motion. Values for primary and coupled ROMs were obtained, showing no significant difference between male and female primary ROMs but a small disparity between male and female coupled ROMs. Regression equations were found to quantify coupled motion throughout the range of axial rotation and lateral bending. The present experimental study also examines the range of horizontally fixed axial rotation of the head to determine the minimum amount of coupled lateral bending that takes place, which has not been measured previously.

The use of the Zebris motion analysis system for measuring cervical spine movements in vivo

The cervical spine exhibits the greatest range of motion among the spinal segments due to the complex interaction of its triplanar components of movement. As a result, measurement of movements of the cervical spine and of the various orthoses used in cervical spine injuries has proved difficult with no one method proving satisfactory. This paper uses the Zebris ultrasonic three-dimensional motion analysis system to measure flexion, extension, range of lateral bending, and range of axial rotation in five similar male and five similar female subjects with no history of neck injuries. The subjects were tested unrestrained and in soft and hard collars, as well as in Philadelphia, Miami J, and Minerva orthoses. Results show that the Minerva is the most stable construct for restriction of movement in all planes in both groups. Looking at these results allows ranking of the measured orthoses in order of their three-dimensional stability. Furthermore, by presenting reproducible data incorporating the composite triplanar movements of the cervical spine, thus allowing comparative analysis of the studied orthoses, they propose the Zebris as a reliable, repeatable, and safe method of measurement of cervical spine motion with low intersubject variability.

Bone sialoprotein-coated femoral implants are osteoinductive but mechanically compromised

Aseptic loosening of femoral implants in total hip replacement remains an unsolved orthopaedic problem. This paper investigates the potential role of bone sialoprotein (BSP) in enhancing bone-implant adherence. As BSP is osteoinductive in rat calvarial models, we investigated whether BSP is similarly osteoinductive when coated onto intramedullary femoral implants. BSP-coated titanium implants were implanted into the femur of female 'Wistar' rats (average weight 215 g) that were sacrificed at days 10, 20 and 30. Harvested femoral implants were subjected to pullout testing and then examined histologically. BSP-coated implants demonstrate osteoinduction when examined histologically. Plugging the femoral canal with BSP prior to inserting the implant neither increased implant pullout strengths nor further increased osteoblastic activity. This study has demonstrated for the first time that BSP is osteoinductive when coated onto femoral implants and inserted into bones subjected to mechanical loading. However, we found that pullout strengths are a function of implant surface topographical characteristics and are not affected by BSP coating or histological osteoinduction.

Development of a model for occipital fixation--validation of an analogue bone material

Several implant systems may be used to fuse the skull to the upper cervical spine (occipitocervical fusion). Current biomechanical evaluation is restricted by the limitations of human cadaveric specimens. This paper describes the design and validation of a synthetic testing model of the occipital bone. Data from thickness measurement and pull-out strength testing of a series of human cadaveric skulls was used in the design of a high-density rigid polyurethane foam model. The synthetic occipital model demonstrated repeatable and consistent morphological and biomechanical properties. The model provides a standardized environment for evaluation of occipital implants.

National study of microphthalmia, anophthalmia, and coloboma (MAC) in Scotland: investigation of genetic aetiology

We report an epidemiological and genetic study attempting complete ascertainment of subjects with microphthalmia, anophthalmia, and coloboma (MAC) born in Scotland during a 16 year period beginning on 1 January 1981. A total of 198 cases were confirmed giving a minimum live birth prevalence of 19 per 100 000. One hundred and twenty-two MAC cases (61.6%) from 115 different families were clinically examined and detailed pregnancy, medical, and family histories obtained. A simple, rational, and apparently robust classification of the eye phenotype was developed based on the presence or absence of a defect in closure of the optic (choroidal) fissure. A total of 85/122 (69.7%) of cases had optic fissure closure defects (OFCD), 12/122 (9.8%) had non-OFCD, and 25/122 (20.5%) had defects that were unclassifiable owing to the severity of the corneal or anterior chamber abnormality. Segregation analysis assuming single and multiple incomplete ascertainment, respectively, returned a sib recurrence risk of 6% and 10% in the whole group and 8.1% and 13.3% in the OFCD subgroup. Significant recurrence risks were found in both unilateral and bilateral disease. In four families, one parent had an OFCD, two of which were new diagnoses in asymptomatic subjects. All recurrences in first degree relatives occurred in the OFCD group with a single first cousin recurrence seen in the non-OFCD group. A total of 84/122 of the MAC cases were screened for mutations in the coding regions of PAX6, CHX10, and SIX3. No pathogenic mutations were identified in the OFCD cases. A single PAX6 homeodomain missense mutation was identified in a subject with partial aniridia that had been initially misclassified as coloboma.

Bullous ichthyosiform erythroderma, developmental delay, aortic and pulmonary stenosis in association with a FRA12A

We present an 11-year-old female with bullous ichthyosiform erythroderma (BIE), learning disability, patent ductus arteriosus and mild stenosis of the aortic and pulmonary arteries. Chromosome analysis showed the expression of the rare folate-sensitive fragile site FRA12A at 12q13 in 8/20 (40%) of blood lymphocytes cultured in folate-deficient medium in the presence of trimethoprim. Her mother and maternal grandmother are phenotypically normal, but her mother shows expression of the same fragile site in 4/20 (20%) of cells cultured under the same conditions. Lymphocytes from the grandmother only showed expression of the fragile site when cultured in the presence of methotrexate in folate deficient medium. Interestingly, two genes (keratin 1 and keratin 2e) which are known to cause BIE map to 12q13. Molecular data is presented excluding three candidate (CCG)n repeats within keratin 1 gene. We present a review of previously reported FRA12A cases and discuss possible molecular explanations for the clinical findings in this patient.

A chromosomal duplication map of malformations: regions of suspected haplo- and triplolethality--and tolerance of segmental aneuploidy--in humans

The distribution of simple autosomal duplications associated with congenital malformations has been analyzed by means of data contained in the Human Cytogenetics Database. For each of the 47 malformations, the frequency of duplication of a given chromosome band associated with the malformation was compared with the overall frequency of duplication of that band recorded in the database. In total, there were 143 malformation-associated chromosomal regions (MACR); 21 of these contained at least one band with a highly significant (P<.001) association. The average number of bands per MACR was 3.1. Eight bands, representing 2.1% of haploid autosomal length, were not involved in any duplication, and we suggest that these are potentially triplolethal. This compares with 31 bands, representing 11% of haploid autosomal length, that were identified in the previously reported deletion map and that were not involved in any deletion and are potentially haplolethal. In both cases, approximately half of these bands are pericentromeric. The longest duplication involves 4.3% of haploid autosomal length, and the longest deletion involves 2.7%.

A chromosomal deletion map of human malformations

Malformations are common causes of pediatric morbidity and mortality, and genetic factors are a significant component of their etiology. Autosomal deletions, in almost all cases, cause a nonspecific embryopathy that presents after birth as growth failure, mental retardation, and multiple malformations. We have constructed a chromosome map of autosomal deletions associated with 47 different congenital malformations, using detailed clinical and cytogenetic information on 1,753 patients with nonmosaic single contiguous autosomal deletions. The 1,753 deletions involved 258 (89%) of 289 possible autosomal bands (by the use of ISCN 400-band nomenclature), giving a total of 4,190 deleted autosomal bands for analysis. We compared the band distributions of deletions associated with common major malformations with the distribution of all 1,753 deletions. We noted 283 positive associations between deleted bands and specific malformations, of which 199 were significant (P<.05, P>.001) and 84 were highly significant (P<.001). These "malformation-associated bands" (MABs) were distributed among 137 malformation-associated chromosome regions (MACRs). An average of 6 MABs in 2.9 MACRs were detected per malformation studied; 18 (6%) of 283 MABs contain a locus known to be associated with the particular malformation. A further 18 (6%) of 283 are in seven recognized specific malformation-associated aneuploid regions. Therefore, 36 (26%) of 137 of the MACRs contain an MAB coinciding with a previously recognized locus or malformation-associated aneuploid region. This map should facilitate identification of genes important in human development.

Guidelines and care pathways for genetic diseases: the Scottish collaborative project on tuberous sclerosis

In Scotland a national audit project has been undertaken to devise evidence-based guidelines for the clinical management of patients with tuberous sclerosis (TS), a dominantly inherited multisystem disorder. In order to facilitate the audit and use of these guidelines a 'Care Pathway' was devised to form the patient records. We describe the process of guideline development for TS and our TS Care Pathway.

Mutilating neuropathic ulcerations in a chromosome 3q13-q22 linked Charcot-Marie-Tooth disease type 2B family

BACKGROUND

Charcot-Marie-Tooth disease type 2 (CMT2) or hereditary motor and sensory neuropathy type II (HMSN II) is an inherited axonal neuropathy of the peripheral nervous system. Three autosomal dominant CMT2 loci have been located on chromosomes 1p35-p36 (CMT2A), 3q13-q22 (CMT2B), and 7p14 (CMT2D) indicating that CMT2 is a genetically heterogeneous disorder.

METHODS

A CMT2 family was examined for linkage to the CMT2A, CMT2B, and CMT2D loci using short tandem repeat polymorphisms.

RESULTS

Suggestive evidence for linkage to 3q13-q22 was found. Recombinations occurred with markers D3S1769 and D3S1267 indicating that the CMT2B locus is located distal to D3S1267 and resides in an interval of 25 cM. Some patients in this family have pronounced sensory disturbances leading to poorly healing ulcerations.

CONCLUSIONS

These unusual sensory signs for CMT were also noted in the only other CMT2B family reported so far, suggesting a distinct clinical phenotype for CMT2B. Exclusion of the locus for hereditary sensory neuropathy type I (HSN I) on chromosome 9q22 indicates that HSN I with mild motor symptoms and CMT2 with prominent sensory abnormalities are not allelic.

Effects of batch to batch variations and test methodology on degree of crystallinity and melting temperature of UHMW-PE as measured by differential scanning calorimetry

The thermal and structural analysis of a total 22 batches from three medical grade ultrahigh molecular weight polyethylene (UHMW-PE) resins was determined using the DSC method. Batch to batch variations of approximately 5% were obtained for the melting temperature and the degree of crystallinity. The variations correlated both to the changes caused by gamma-irradiation sterilization and subsequent aging, and to the differences in DSC results obtained from various laboratories on materials believed to exhibit essentially similar clinical performances. Varying the sample weight from 4.4 to 27.1 mg resulted in a significant relative increase of 5% in the degree of crystallinity. The study shows that the standard double melting/recrystallisation procedure for DSC evaluation produces variations in the melting behaviors of approximately the same magnitude as those indicated by batch lot or sterilization/aging.

An estimation of the number of susceptibility loci for isolated cleft palate

The existence of a major gene (or genes) that contributes significantly to the familial clustering of cleft lip with or without cleft palate (CL(P)) has been suggested by genetic epidemiology studies and supported by patient-control genotype association studies with a candidate gene. Here we present an analysis of the familial recurrence risk data for isolated cleft palate (CP) and show that an oligogenic model with six genes of equal effect fits the data best. The discrimination between alternative models is, however, poor and a major locus that explains half of the familial recurrence is plausible. The prospects for identification of susceptibility loci for CP are discussed.

Orientation of the cruciate ligament in the sagittal plane. A method of predicting its length-change with flexion

We have studied the kinematics of the knee in the sagittal plane, using a four-bar linkage as model, and assuming that a "neutral fibre" in each ligament remains isometric throughout flexion. We devised a computer program to calculate the distance separating any pair of points, one on each bone, for various cruciate attachments at various angles of flexion. The parameters for the linkage in four cadaveric knees were obtained by marking the centre of attachment of the cruciate ligaments with tacks and taking lateral radiographs. The movements of the bones were then calculated, in the computer model, for various attachments of "replacement" ligament fibres, the distance between the attachment sites being plotted against the angle of flexion. It was then possible to define zones around the isometric attachment points within which changes in length would be predictable. Our results show that the position of the femoral sites of attachment of both anterior and posterior cruciate replacement was more critical than that of the tibial attachments.