Improved adherence to hip fracture standards reduces mortality after hip fractures

BACKGROUND

Hip fractures are increasing in incidence due to increasing life expectancy. Mortality continues to improve but it is important to explore which factors are responsible for driving improvements.

METHODS

A cohort of hip fracture patients predating SARS-CoV-2 was examined to determine the predictors of adherence to the six Irish Hip Fracture Standards (IHFS) and the impact of adherence on short (30 day) and long term (1 year) mortality. Our primary aim was assess the impact of a single HFS and cumulative number of HFS on mortality after hip fracture. Our secondary aim was to determine the impact of the HFS which are intrinsically linked to specialist Geriatric care.

RESULTS

Across 962 patients, over 5 years, the factors which were associated with adherence to HFS were female gender, increasing ASA grade and being nursed on an orthopaedic ward. Patients with increasing ASA were more likely to have met HFS 4-6 (Geriatrician review HFS4, bone health HFS5 & specialist falls assessment HFS6), less likely to have surgery within 48 h are more likely to develop a pressure ulcer. If the patient was not nursed on an orthopaedic ward all HFS were less likely to be met. At 30 days HFS 4-6 were associated with a statistically significant odds ratio (OR) of being alive, while at one year HFS 1 (admitted to an orthopaedic ward within 4 h), 5 and 6 were associated with a statistically significant OR of being alive. As increasing numbers of hip fracture standards were met patients were more likely to be alive at 30 days and one year.

CONCLUSION

This study has identified that improved adherence to hip fracture standards are associated with improved mortality at 30 days and one year.

OP0013 LOSS OF SYNOVIAL TISSUE MACROPHAGE HOMEOSTASIS PRECEDES RHEUMATOID ARTHRITIS CLINICAL ONSET

Background

Synovial tissue macrophages significantly contribute to Rheumatoid Arthritis, yet the precise nature/function of macrophage subsets within the inflamed joint remains unexplored.

Objectives

To fully explore the spectrum of distinct macrophage activation states residing within the synovium of RA, at risk and healthy individuals.

Methods

Single-cell synovial tissue suspensions from RA (n=44), IAR (n=5), HC (n=11), PsA (n=11) and OA (n=4) were obtained, and synovial macrophage subsets examined by advanced multiparameter flow cytometric analysis, bulk RNA-sequencing, metabolic and functional assays.

Results

Multidimensional analysis identifies enrichment of CD206+CD163+ synovial-tissue macrophages co-expressing CD40 in the RA joint compared to healthy synovial-tissue, with frequency of CD206+CD163+CD40+ macrophages associated with increased disease activity and treatment response. In contrast, CX3CR1-expressing macrophages which form a protective barrier in healthy synovium are significantly depleted in RA. Importantly this signature of enriched CD40 expression coupled with depleted CX3CR1 expression is an early phenomenon, occurring prior to clinical manifestation of disease in individuals ‘at-risk’ of RA (IAR). RNAseq and metabolic profiling of sorted RA synovial-macrophages identified that this population is transcriptionally distinct, displaying unique inflammatory, phagocytic and tissue-resident gene signatures, paralleled by a bioenergetically stable profile as indicated by NAD(P)H emission. Functionally CD206+CD163+ RA macrophages are potent producers of pro-inflammatory mediators (reversed by CD40-signalling inhibition) and induce an invasive phenotype in healthy synovial-fibroblasts. These findings identify a distinct pathogenic population of synovial-tissue macrophage involved in shaping the immune response in RA. Crucially, this signature is present pre-disease representing a unique opportunity for early diagnosis and therapeutic intervention.

Conclusion

We have identified a novel population of tissue-resident macrophages in the RA synovium which are transcriptionally/metabolically distinct and capable of contributing to disease pathology. Uncovering the molecular patterns and cues that transform this immunoregulatory macrophage population into a dysfunctional inflammatory activation state may provide opportunities to reinstate joint homeostasis in RA patients.

Disclosure of Interests

Megan Hanlon: None declared, Mary Canavan: None declared, Nuno Neto: None declared, Qingxuan Song Employee of: Employee of Janssen Pharmaceuticals, Phil Gallagher: None declared, Ronan Mullan: None declared, Conor Hurson: None declared, Barry Moran: None declared, Michael Monaghan: None declared, Sunil Nagpal Employee of: Employee of Janssen Pharmaceuticals, Douglas Veale Consultant of: Janssen, Eli Lilly, Pfizer, Ursula Fearon Consultant of: Janssen, Eli Lilly, Pfizer

Hypersensibilité au vaccin anti-COVID ? analyses de 1000 avis allergologiques

Introduction (contexte de la recherche)

Les services d’allergologie ont été fortement sollicités en raison de l’appréhension vis-à-vis du risque allergique des vaccins contre la COVID-19.

Objectif

Nous rapportons les 1000 premières prises en charge proposées et le résultat des investigations allergologiques réalisées.

Méthodes

Nous avons mis en place un système d’avis-COVID par mail à l’aide d’un questionnaire. Ceci nous a permis de colliger, de façon rétrospective les données démographiques des patients, les conduites à tenir proposées, en fonction des données cliniques fournies et des recommandations de la SFA. Pour certains, des tests cutanés ont été nécessaires : prick-test aux PEGs 3500/1500 et polysorbate 80 avec des concentrations maximales respectives de 100 mg/mL et 1000 mg/mL. Lorsque des fonds de flacon de vaccin étaient disponibles, nous avons réalisé : prick-test et IDR jusqu’à leur concentration pure. Certaines vaccinations jugées à risque ont été réalisées dans le service.

Résultats

Du 20 janvier au 24 novembre 2021, 1000 avis allergologiques ont été donnés par mail en dehors des heures de consultation. Il s’agissait de 773 avis pré-vaccinaux et 227 post-vaccinaux. L’âge moyen des patients était de 55 ans, avec une majorité de femmes. Nous avons levé la contre-indication allergologique à la vaccination dans 99,4 % des cas. Elle a été recommandée en centre de vaccination conventionnel pour 44 % sans précaution particulière, 31 % sous antihistaminique, 30 % avec 30 minutes de surveillance. 31 patients ont été vaccinés dans notre service sans réaction. L’indication de tests cutanés a été retenue dans 6,9 % des cas. Nous avons mis en évidence une sensibilisation aux excipients et aux vaccins chez 4 patients du groupe pré-vaccinal et chez une patiente du groupe post-vaccinal qui a bénéficié d’une désensibilisation avec succès.

Conclusions

La gestion par mail des avis-COVID a permis de limiter les consultations dédiées en présentiel et de maintenir l’intégralité des activités du service. Nous avons proposé une réponse rapide avec traçabilité écrite, souvent exigée. Seuls 4 patients restent à ce jour contre-indiqués à la vaccination en raison d’une allergie aux PEGs.

1235 A Multi-Site Review of Second Hip Fractures Across 6 Dublin Teaching Hospitals

Introduction

Hip fractures are a common presentation to Irish hospitals with 3,701 hip fractures recorded by 16 hospitals in the Irish Hip Fracture Database (IHFD) in 2019. Second hip fractures (HF2) make up a significant proportion of hip fractures and represent an opportunity to prevent subsequent fragility fracture.

Method

Hip fracture datasheets from 2019 in six Dublin hospitals were analysed.

Results

1,284 hip fractures in total were recorded in 2019 in these six hospitals. 112 of these were second hip fractures (8.72%). 24.1% of patients had a HF2 in year 1 post their first hip fracture (HF1). 14.3% of patients had a HF2 in Year 2, 8% in Year 3, 8.9% in Year 4 and 6.3% in Year 5. 17.9% of patients had an HF2 at an unknown time in relation to their HF1. 57.6% of all patients with any hip fracture were started on bone protection medications (BPMs) during their admission. 18.9% continued a pre-admission prescription. 7% of all patients were previously assessed and determined not to require BPM. 6.9% of patients were awaiting outpatient department (OPD) assessment for bone protection. 8.6% had no assessment for bone protection conducted. Of all patients with an HF2, 48.2% were started on BPMs on admission with their HF2. 33% continued BPMs started pre-admission.

Discussion

In 2019, approximately 1 in 10 hip fractures were second hip fractures. Evidence suggests that fracture liaison services represent a viable, economic means of preventing second hip fractures to improve patient outcomes and reduce healthcare expenditure.

1256 Orthopaedics and The COVID19 Pandemic: Was Achilles Just A “Weekend Warrior”?

Background

The COVID19 pandemic has affected the types of trauma being operated on by Orthopaedic surgeons. Lifting of restrictions pertaining to sports saw a sudden return to play for many people after a period of inactivity. Achilles tendon ruptures are associated with these episodic athletes. In our institution, we appeared to have a large number of these injuries within a short space of time. We hypothesised that Phase 3 of “Lockdown”, where all sports were allowed to return, led to increased Achilles tendon rupture rates vs. the same period in 2019 due to a prolonged period of inactivity.

Method

Data from electronic theatre logbooks of all operations performed in the trauma theatre from 27th March 2020 (Lockdown begins) to 31st July 2020 and 27th March 2019 to 31st July 2019 was collected.

Results

772 cases were performed in 2019. There were 17 Achilles tendon ruptures in that period (2.2%). 14 of these occurred after Phase 3. 555 cases were performed in 2020. There were 13 Achilles tendon ruptures in that period (2%). 11 of these occurred after Phase 3.

Conclusions

Overall, there was a greater number and greater rate of Achilles tendon ruptures in 2019 vs. the equivalent “Lockdown” period in 2020. 8 of the 11 occurring after Phase 3 in 2020 occurred in the month of July. This led the authors to believe they were occurring more frequently. In conclusion, the COVID19 pandemic restrictions and subsequent return to play after inactivity does not increase the rate of Achilles tendon rupture.

1244 The TAL Suction Retractor: A Simple Technique for Visualising the Transverse Acetabular Ligament (TAL) During Total Hip Replacement (THR) Surgery

Introduction

The transverse acetabular ligament (TAL) is an anatomical landmark that is of particular use during primary total hip replacements (THR). Visualisation is important to aid the orientation of the acetabular cup and it is a structure that can be identified in virtually every primary hip replacement surgery. We introduce a simple technique to facilitate this.

Method

A thoracic suction catheter is taped to the distal end of a blunt Hohmann’s retractor with two steristrips wrapping around the catheter and retractor leaving approximately 1-1.5cm of retractor exposed. Our preference is for a thoracic suction catheter with side holes and a proximal end which allows direct connection with the tip of the Yankauer suction. The blunt Hohmann’s retractor is used as the inferior acetabular retractor in the usual way, placed inferior to the transverse acetabular ligament, resting on the posterior ischial surface. The catheter suction tip should lie just under the TAL, in the most dependant point of the wound.

Results

The TAL suction catheter can be used continuously or intermittently to facilitate visualisation of the TAL during reaming, trialling, and acetabular cup placement. The TAL suction retractor provides suction in the most dependant point of the surgical wound, preventing unnecessary movement and facilitates a clutter-free surgical field leading to more streamlined and efficient surgery with potential reduced operative times.

Conclusions

The transverse acetabular ligament (TAL) suction retractor is a simple improvised surgical tool that makes it easier to visualise the TAL during acetabular preparation in total hip replacements.

AB0018 ACCUMULATION OF FUNCTIONALLY MATURE CD1C+ DENDRITIC CELLS CONTRIBUTES TO SYNOVIAL INFLAMMATION IN INFLAMMATORY ARTHRITIS

Background:

Myeloid Dendritic Cells (DC) are potent antigen presenting cells that can be subdivided into CD141 and CD1c+ DC. We have previously reported an unacknowledged role for CD141+DC in the IA synovium. However, the identification and function of CD1c+ DC in the IA synovium has yet to be fully elucidated.

Objectives:

To investigate if CD1c+DC reside in the IA synovium and ascertain if they represent a unique population, distinct from peripheral CD1c+DC and if they contribute to synovial inflammation.

Methods:

Synovial tissue (ST) biopsies and synovial fluid mononuclear cells (SFMC) were obtained via arthroscopy and healthy control (HC) ST was obtained during ACL surgery. Synovial tissue single cells suspensions were generated following enzymatic and mechanical digestion. Single cell analysis of synovial tissue cell suspensions, along with PBMC and SFMC was performed by multicolour flow cytometry. CD1c+DC were sorted from IA synovial fluid and peripheral blood and bulk RNA sequencing was performed. CD1c+DC functionality and maturation was assessed using OVA DQ phagocytosis assays, multiplex ELISA and DC: T cell cocultures.

Results:

Within the circulation the frequency of CD1c+DC are significantly decreased in IA peripheral blood compared to HC (p<0.01) in addition to expressing significantly higher levels of the maturation markers CD80 (p<0.01) and CD40 (p=0.08). IA peripheral blood DC also express significantly higher levels of CXCR3 (p<0.01) and CCR7 (p<0.05) compared to HC - suggestive of DC migration from the periphery to the synovium. Following RNA-seq analysis, IPA and differentially expressed gene (DEG) analysis revealed an enrichment in genes involved in DC maturation, TLR signalling and chemokine signalling in IA peripheral blood compared to HC. In support of the hypothesis that DC migrate and accumulate in the IA synovium, CD1c+ DC were identified in IA ST and were significantly enriched compared to IA peripheral blood (p<0.01). IA ST CD1c+DC express significantly higher levels of the activation marker CD80 compared to IA peripheral blood (p<0.05) or HC ST (p<0.05). Upon examination of IA synovial fluid, we report similar findings to ST, whereby CD1c+DC are enriched in synovial fluid compared to PB (p<0.001). Moreover, RNA sequencing and PCA analysis of synovial versus blood CD1c+DC revealed distinct transcriptional variation between both sites. Functionally, synovial CD1c+DC express higher levels of the maturation markers CD80, CD83, CD40, PD-L1 and BTLA (all p<0.05) and have distinct coexpression of these maturation markers which is unique to the synovium. Synovial CD1c+DC are less phagocytic compared to peripheral blood DC, have decreased production of MMP1 and MMP9 and importantly are still capable of additional activation in-vitro. Finally, synovial CD1c+DC induce the proinflammatory cytokines TNFα, GMCSF, IL-17a and IFNγ from CD4+ T-cells in allogeneic DC: T cells cocultures.

Conclusion:

Mature circulatory CD1c+DC migrate and accumulate in the IA synovium. Synovial DC are present in the IA synovium in a mature state, have distinct tissue specific characteristics and can induce proinflammatory CD4+T cell responses.

Acknowledgements:

We would like to thank all the patients who contributed to this study

Disclosure of Interests:

Mary Canavan: None declared, Viviana Marzaioli: None declared, Vipul Bhargava Employee of: Janssen Research and Development, Sunil Nagpal Employee of: Janssen Research and Development, Phil Gallagher: None declared, Conor Hurson: None declared, Ronan Mullan: None declared, Douglas Veale Speakers bureau: Abbvie, Janssen, Novartis, Pfizer, MSD, UCB, Consultant of: Abbvie, Janssen, Novartis, Pfizer, MSD, UCB, Grant/research support from: Pfizer, Janssen, AbbVie, UCB, Ursula Fearon Speakers bureau: Abbvie, Grant/research support from: Pfizer, Janssen, Abbvie, UCB

OP0028 CD206+CD163+ PATHOGENIC MACROPHAGES ENRICHED IN RHEUMATOID ARTHRITIS SYNOVIAL TISSUE WITH DISTINCT TRANSCRIPTIONAL SIGNATURES

Background:

Synovial tissue macrophages are an exquisitely plastic pool of innate cells that play a key role in RA disease progression. However, the precise nature, diversity, and function of macrophage subsets within the inflamed joint remains unexplored.

Objectives:

Therefore, the aims of this study are to phenotypically, transcriptionally and functionally characterise synovial tissue macrophages residing within the inflamed joint.

Methods:

Rheumatoid Arthritis, Psoriatic Arthritis, Osteoarthritis and healthy control synovial-tissue biopsies and synovial-fluid mononuclear cells were analysed using the following panel (CD40,-CD45,-CD64,-CD68,-CD163,-CD206,-CD253,-CCR4,-CCR7,-CXCR1,-CXCR3). CD206+CD163+ and CD206-CD163- macrophages were sorted from RA synovial-tissue by FACSAria sorter; RNAseq and FLIM analysis, autologous T-cell co-culture and heathy fibroblast experiments performed. Cytokine expression was measured by MSD immunoassay.

Results:

RA synovial tissue and fluid macrophages display markers typical of both M1 (CD40+CD253+) and M2 (CD206+CD163+) macrophages with a spectrum of macrophage activation states identified. Within this spectrum, significant enrichment of dominant CD206+CD163+ macrophage-subtype is present in synovial tissue versus fluid (p<0.05). CD206+CD163+ synovial tissue macrophages express significantly more CD40 than synovial fluid (p<0.0003), positively correlate with disease activity (r=0.6, p<0.01), with baseline levels predicting response to therapy (p<0.05). Moreover, CD206+CD163+CD40+ macrophages are enriched in RA synovial tissue compared to PsA and OA pathotypes (p<0.05). While the CD206+CD163+ subset is present in healthy synovial tissue, expression of CD40 is completely absent in healthy synovium (p<0.05) with dramatically decreased expression of CX3CR1 on RA macrophages. RNA-seq analysis indicates that CD206+CD163+ population is transcriptionally distinct from synovial tissue CD206-CD163-, synovial fluid CD206+CD163+, and RA monocyte-derived M1/M2 macrophages, with unique tissue-resident gene signatures. Moreover, differing metabolic demands between CD206+CD163+ and CD206-CD163- subsets was demonstrated by RNAseq and FLIM analysis. CD206+CD163+ macrophages enhance autologous T-cell responses, spontaneously secrete high levels of pro-inflammatory cytokines and activate healthy fibroblasts towards pro-inflammatory mechanisms thus further contributing to the local inflammatory response. Finally, inhibition of CD40 activity abrogates the expression of pro-inflammatory mediators (TNFa, IL-1B, IL-6, IFNy) and induces IL-10 expression in sorted CD206+CD163+ synovial tissue-macrophages suggesting a key role for CD40 in driving this pathogenic phenotype.

Conclusion:

This data identifies for the first-time enrichment of a previously undescribed dysfunctional dominant and transcriptionally distinct macrophage subtype in RA synovial tissue. Taken together, this data provides a greater understanding of the critical role tissue-resident macrophages play in perpetuating inflammation in RA. Further investigation of the molecular patterns and cues that shape specific synovial macrophage subsets may provide opportunities to reinstate RA joint homeostasis.

Disclosure of Interests:

Megan Hanlon: None declared, Mary Canavan: None declared, Qingxuan Song Employee of: Janssen Research & Development, Nuno Neto: None declared, Phil Gallagher: None declared, Ronan Mullan: None declared, Conor Hurson: None declared, Michael Monaghan: None declared, Sunil Nagpal Employee of: Janssen Research & Development, Douglas Veale Speakers bureau: Abbvie, Janssen, Novartis, MSD, Pfizer, UCB, Consultant of: Abbvie, Janssen, Novartis, MSD, Pfizer, UCB, Grant/research support from: Janssen, Abbvie, Pfizer, UCB, Ursula Fearon Speakers bureau: Abbvie, Grant/research support from: Janssen, Abbvie, Pfizer, UCB

Trends in hip fracture care in the Republic of Ireland from 2013 to 2018: results from the Irish Hip Fracture Database

Hip fractures continue to be one of the most serious and costly injuries suffered by older people globally. This paper describes the development of a national hip fracture audit and summarises the first 6 years of data from the Republic of Ireland. This can help inform care, standards and outcomes of hip fracture patients.

INTRODUCTION

Ireland has one of the highest standardised rates of hip fracture in the world behind northern European countries. The Irish Hip Fracture Database (IHFD) was established in 2012 to drive clinical and organisational improvements in quality and effectiveness of hip fracture care. This paper describes the progression of the IHFD between 2013 and 2018 and identifies trends and areas for improvement.

METHODS

The IHFD is a clinically led, web-based audit, with data collected through the national Hospital Inpatient Enquiry (HIPE) electronic system, the principal source of information from publicly funded acute hospitals in Ireland. Eligible cases are aged ≥ 60 years with hip fracture as defined by IHFD or with other specified hip fracture excluding periprosthetic fractures. As of 2015, all 16 trauma-receiving hospitals within Ireland submitted data. Demographics and adherence to six national quality standards are described.

RESULTS

A total of 17,983 cases were included in the analysis. National coverage has increased from 63% in 2013 to 99% in 2018. Demographic characteristics are unchanged, but higher levels of comorbidity are seen. Internal fixation and hemiarthroplasty are the most common modes of surgical repair with two-thirds of cases receiving spinal rather than general anaesthesia. Increasingly patients are being assessed by a geriatrician (11% in 2013 to 69% in 2018) and receive a bone health assessment (65% in 2013 to 84% in 2018).

CONCLUSION

While some hip fracture standards have improved, further improvements are required to compare favourably internationally. Reduction of surgical delay and ensuring early mobilisation post-operatively are immediate priorities for the IHFD.

Knowledge, Attitudes and Practices of Non-Consultant Hospital Doctors In The Immediate Post-Fall Period

Aim The aim of this study is to determine the knowledge, attitudes and practices of Non-Consultant Hospital Doctors (NCHDs) in the immediate post-fall period. Methods A survey study design was employed using an online questionnaire of all NCHDs in SVUH comprising 15 questions that blend dichotomous, multiple choice, scaled and open-ended questions to determine knowledge, attitudes and practices of NCHDs across three constructs; injury management, falls prevention and fracture prevention. Descriptive statistics was used to analyse data. Results There was a 40% response rate (n=105). The respondents reported dissatisfaction with their standard of falls assessment training (mean 4/10). Between 60-70% of NCHDs do not routinely determine hip trauma, joint tenderness, syncope, use of anti-coagulants, visual symptoms, amnesia or vomiting. Half of respondents (n=57) rarely or never rationalised medications. The main reasons for this are lack of knowledge of alternatives (63%), time constraints (65%), benefits outweighing the risks (80%) and reluctance to interfere with care of another medical team (86%). Only 9% always consider a bone health review. Discussion A targeted education programme in the areas of hip assessment, neurological assessment, syncope management, medication rationalisation and bone protection is warranted.

Clinician approach to diagnosis of stress fractures including bisphosphonate-associated fractures

Stress fractures are repetitive strain injuries that occur in normal bones and in abnormal bones. Stress fractures share many features in common but differences depend on the status of the underlying bone. This review article for clinicians addresses aspects about stress fractures with particular respect to fatigue fractures, Looser zones of osteomalacia, atypical Looser zones, atypical femoral fractures associated with bisphosphonate therapy and stress fractures in Paget's disease of bone.

Rapid prototyping in the assessment, classification and preoperative planning of acetabular fractures

AIM

To evaluate the use of rapid prototyping in the assessment, classification and preoperative planning of acetabular fractures.

INTRODUCTION

The complex three-dimensional anatomy of the pelvis and acetabulum make assessment, classification and treatment of fractures of these structures notoriously difficult. Conventional imaging only provides two-dimensional images of these fractures. While interpretation of traditional imaging techniques becomes better with experience, novel techniques may assist in the understanding of these complex injuries.

METHODS

Twenty patients with acetabular fractures were studied. Life size three-dimensional models were manufactured from standardised CT scans, using the rapid prototyping process, selective laser sintering. Each model was presented to the operating surgeon prior to surgery. The surgeons found that the models greatly assisted in their understanding of the personality of the fracture. Three consultant orthopaedic surgeons and three senior trainees were asked to classify each fracture using conventional radiographs (AP pelvis, Judet views and CT scans) and then using the model. The kappa statistic was used to evaluate inter- and intraobserver agreement.

RESULTS

Interobserver agreement was not absolute using either conventional radiographs or the models. For the consultants the kappa statistic using conventional radiographs was 0.61 while the kappa value using the model was 0.76 (p<0.05). For the trainees the kappa value was 0.42, using conventional radiographs and 0.71 using the model (p<0.01).

CONCLUSION

Full sized models of acetabular fractures greatly assisted surgeons understand the personality of complex fractures prior to surgery and have been shown in this study to significantly reduced the degree of interobserver variability in fracture classification. This effect is particularly evident for less experienced surgeons. This technique is available and relatively inexpensive. The use of these models should prove invaluable as a tool to aid clinical practice.

Abdominal aortic aneurysm repair and colonic infarction: a risk factor appraisal

OBJECTIVE

Colonic infarction is a recognized complication of abdominal aortic aneurysm (AAA) surgery. The clinical difficulty in establishing the diagnosis combined with the patient's poor physiological status is usually associated with a fatal outcome. We assessed our experience with this problem to identify a possible risk factor profile for these patients.

METHOD

Patients records were identified from the operative logs, intensive care unit, Hospital Inpatient Enquiry system and vascular unit databases over a 6-year period.

RESULTS

A total of 405 patients underwent AAA repair during this period; 140 as emergency ruptures. Nine patients were identified from the databases with known colonic infarction (2.2%). One was a woman. The mean age was 70 years. Seven patients had emergency ruptures (5%). Twenty independent risk factors were analysed using univariate and multivariate logistic regression models. Significant risk factors identified by using a multivariate analysis included the nature of the presenting patient, preoperative hypotension, prolonged cross-clamp time, intra-operative ischaemia and postoperative acidosis. Confirmatory diagnosis was made by colonoscopy in eight patients. One patient survived following the salvage surgery. The mean duration of survival was 10.5 days. The overall mortality was 89% of patients.

CONCLUSION

In our unit infrarenal AAA repair has a 2.2% rate of colonic infarction. A definitive diagnosis is best made by colonoscopy. A risk factor profile for the development of colonic infarction may be constructed on the basis of specific clinical parameters. Earlier intervention on the basis of this profile may ultimately reduce the current excessive mortality.

Revision of the Sheehan total knee arthroplasty

The use of the Sheehan knee prosthesis extended from 1971 to 2002. It incorporated a semi-constrained hinge with intra-medullary stems cemented into the femur and tibia. While some authors have reported excellent short-term results, others have reported revision rates of up to 31% at 5--10 years. The aim of this study was to review the senior author's experience in revising these arthroplasties. We review 54 Sheehan total knee replacements and discuss the difficulties encountered during first and subsequent revisions and the often-complex reconstruction techniques used to overcome these.

Above-knee Ilizarov external fixation for early periprosthetic supracondylar femoral fracture--a case report

Supracondylar femoral fractures above a total knee replacement are rare injuries that may be challenging to treat. We present a 60-year-old woman who sustained a supracondylar femoral fracture 10 days following a total knee replacement. This patient had multiple risk factors. The fracture was not deemed amenable to conventional treatment. This patient underwent fixation of her femoral fracture above a total knee replacement using a two-ring above-knee Ilizarov external fixator. This allowed full mobilization of the affected limb during fracture healing. The fixator was removed at 10 weeks, at which time the fracture was solidly healed. At the most recent follow-up, 14 months from injury, she was fully weight-bearing without walking aids and had a knee range of motion of 0-120 degrees .

The natural history of the periacetabular fragment following Ganz osteotomy

The vascularity of the acetabular free fragment in Ganz osteotomies has remained a concern. This study aims to assess the role of MR imaging in the postoperative evaluation of Ganz osteotomies. Twenty patients (19 females, 1 male), average age 24 years (range, 12-36 years), had sequential magnetic resonance imaging studies of the pelvis at 6 weeks and 6 months following Ganz osteotomies. Normal healing with no evidence of periosteotomy edema was seen in 17 patients at 6 weeks. Three patients showed evidence of reduced vascularity. In two of these, there were focal changes suggestive of subclinical ischemia. The other had gross signal changes in the osteotomy fragment suggestive of diffuse ischemia. The patients with focal changes were asymptomatic and had normal 6-month scans. The patient with diffuse changes complained of persistent groin pain, which resolved after 4 months. The 6-month scan showed some persistent vascular changes. The scan at 1 year showed complete resolution. The study suggests that Ganz osteotomy has minimal effect on the vascularity of the acetabular free fragment.

Assessment of degree of internal carotid artery stenosis based on duplex velocity measurements using an artificial neural network

Background

Duplex imaging is increasingly used as a stand-alone investigation before carotid endarterectomy. There is concern regarding the wide variation in diagnostic methods of grading internal carotid artery (ICA) stenosis using duplex velocity criteria. The aim of the study was to design an artificial neural network (ANN) that is able to provide a measure of the degree of ICA stenosis based on the four most commonly used duplex velocity profiles.

Methods

One hundred and four consecutive patients who were admitted for assessment of carotid occlusive disease were included. All patients underwent arch injection digital subtraction angiography and carotid duplex ultrasonography. Peak systolic velocity (PSV) and end-diastolic velocity (EDV) in the ICA and common carotid artery (CCA) were measured. The degree of angiographic stenosis was measured by two blinded investigators. A three-layered perceptron ANN was constructed using the NeuroSolutionsTM version 1 software program (NeuroDimension, Gainesville, FL, USA). The accuracy of the model in predicting the degree of ICA stenosis was expressed as the mean squared error (MSE) of the actual degree of angiographic stenosis. The performance of the neural network model was compared with that of the linear regression model at predicting the degree of ICA stenosis and classifying a degree of ICA stenosis greater than 50 per cent.

Results

One hundred and sixty-eight carotid bifurcations were available for analysis. The MSE of the ANN at predicting the degree of ICA stenosis was 0·096 (overall accuracy of 84 per cent), which was superior to a linear regression model (MSE 0·132; overall accuracy 73 per cent) (P &lt; 0·001). Both models were equally accurate at identifying a degree of ICA stenosis greater than 50 per cent (ANN accuracy 0·91 versus regression model accuracy 0·89; P = 0·09).

Conclusion

Neural network algorithms are able to predict the degree of ICA stenosis with reasonable accuracy and outperform linear regression analysis on the basis of a limited set of duplex velocity measurements. With further refinement, ANN models could replace duplex criteria in assessment of the degree of ICA stenosis.

Thoracoscopic management of primary spontaneous pneumothorax

BACKGROUND

Video-assisted thoracoscopic surgery (VATS) is the preferred option for the surgical management of primary spontaneous pneumothorax (PSP).

AIMS

To evaluate the role of thoracoscopic blebectomy with and without chemical pleurodesis.

METHODS

A retrospective study was performed on 113 consecutive cases carried out in one unit. RESULTS; One hundred and thirteen VATS procedures were performed on 108 patients. The mean age was 23 years (range 14-45). The male to female ratio was 82:26. Recurrent pneumothorax was the indication for surgery in 80%. Conversion to an open procedure was required in 10 cases (9%), most commonly due to severe adhesions. Successful endoscopic blebectomy was performed in 98 cases (87%), 48 of which had an additional chemical pleurodesis. Follow-up is currently to a mean of 28 months. Recurrence has occurred in eight cases, including only three in the group managed with additional chemical pleurodesis (6.25%).

CONCLUSION

VATS with blebectomy and chemical pleurodesis is a safe and effective procedure in the management of PSP.