Publications by authors named "Jim Kennedy"

23 Publications

  • Page 1 of 1

The use of three rods in correcting severe scoliosis.

Spine Deform 2021 Feb 10. Epub 2021 Feb 10.

Department of Orthopaedic Surgery, Hospital for Sick Children, 555 University Avenue, Toronto, ON, M5G 1XB, Canada.

Purpose: The three-rod technique, utilising a short apical concavity rod is an option to achieve controlled correction in severe scoliosis. We describe this technique, the complications encountered, and the long-term outcomes.

Method: All paediatric patients who had at least 2 years follow-up after undergoing corrective surgery for scoliosis ≥ 100° using 3 parallel rods were included. Radiographs were assessed to evaluate the correction and clinical records examined for any loss of correction, complications, revision procedures or neuromonitoring events.

Results: Twenty-five patients met the inclusion criteria. Four underwent prior anterior fusion to prevent crankshaft phenomenon. The mean angle of the deformity was 112.0° (range 100.3-137.1). Mean maximal kyphosis was 48.8° (range 11.4-78.8°) and mean curve flexibility 4.4% (range 0-37.0%). Intraoperative traction achieved an average of 70.4% (95% CI 56.6-84.1%). Nine patients (39%) showed a reduction in MEPs during definitive surgery. All returned to within 75% of baseline by the end of surgery. All patients had normal postoperative neurology. One patient underwent removal of hardware for late infection. The mean overall Cobb correction was 55.7° (95% CI 50.2-61.2°), equating to 50.2% (95% CI 44.9-55.4%) of the mean initial deformity. Thoracic kyphosis reduced by a mean of 18.2° (95% CI 12.8-23.6°).

Conclusion: Our series suggests that three-rod constructs are able to safely and effectively achieve 50% correction of severe scoliosis.
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http://dx.doi.org/10.1007/s43390-021-00300-yDOI Listing
February 2021

Establishing a Virtual Clinic for Developmental Dysplasia of the Hip: A Prospective Study.

J Pediatr Orthop 2021 Apr;41(4):209-215

Department of Trauma and Orthopaedics, Crumlin, Children's Health Ireland.

Background: The aim was to describe the introduction and operation of a virtual developmental dysplasia of the hip (DDH) clinic. Our secondary objectives were to provide an overview of DDH referral reasons, treatment outcomes, and adverse events associated with it.

Methods: A prospective observational study involving all patients referred to the virtual DDH clinic was conducted. The clinic consultant delivered with 2 DDH clinical nurse specialists (CNS). The outcomes following virtual review include further virtual review, CNS review, consultant review or discharge. Treatment options include surveillance, brace therapy, or surgery. Efficiency and cost analysis were assessed.

Results: Over the 3.5-year study period, 1002 patients were reviewed, of which 743 (74.2%) were female. The median age at time of referral was 7 months, (interquartile range of 5 to 11) with a median time to treatment decision of 9 days. Median waiting times from referral to treatment decision was reduced by over 70%. There were 639 virtual reviews, 186 CNS reviews, and 144 consultant reviews. The direct discharge rate was 24%. One hundred one patients (10%) had dislocated or subluxed hips at initial visit while 26.3% had radiographically normal hips. Over the study period 704 face to face (F2F) visits were avoided. Cost reductions of €170 were achieved per patient, with €588,804 achieved in total. Eighteen parents (1.8%) opted for F2F instead of virtual review. There were no unscheduled rereferrals or recorded adverse events.

Conclusion: We report the outcomes of the first prospective virtual DDH clinic. This clinic has demonstrated efficiency and cost-effectiveness, without reported adverse outcomes to date. It is an option to provide consultant delivered DDH care, while reducing F2F consults.

Level Of Evidence: Level III.
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http://dx.doi.org/10.1097/BPO.0000000000001755DOI Listing
April 2021

Mud Dauber Nests as Sources of Spiders in Mercury Monitoring Studies.

Environ Toxicol Chem 2021 Jan 19. Epub 2021 Jan 19.

Department of Veterinary Medicine, University of Alaska Fairbanks, Fairbanks, Alaska, USA.

Identifying ecosystems where biota may be contaminated with hazardous levels of methylmercury (MeHg) is a challenge. One widely used approach for determining site-specific MeHg contamination is to monitor MeHg contamination in sentinel species. Terrestrial shoreline spiders that consume emergent aquatic insects (e.g., midges and mayflies) have been proposed as sentinels of MeHg contamination of aquatic ecosystems. The purpose of the present study was to determine whether a novel sampling technique, collection of spiders from nests of mud dauber wasps (Sphecidae), would be an efficient method for capturing MeHg-contaminated shoreline spiders for use as sentinels in ecological risk assessments. Mud dauber nests were collected near the Clear Fork of the Trinity River in Fort Worth, Texas (USA) on 3 dates from 4 human-made structures. Nests contained 627 unconsumed spiders from 5 families: Araneidae, Salticidae, Thomisidae, Oxyopidae, and Theridiidae. Methylmercury concentrations ranged from 12.2 to 56.3 ng/g wet weight in Thomisidae and Araenidae, respectively. Methylmercury concentrations of the spiders were generally low relative to risk thresholds for adult birds, but a few families of spiders could pose a risk to nestlings. Although mud dauber nests have been recognized as a source of spiders for biodiversity studies, the present study is the first to demonstrate the potential use of spiders collected from mud dauber nests for ecotoxicology studies. Environ Toxicol Chem 2021;00:1-6. © 2021 SETAC.
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http://dx.doi.org/10.1002/etc.4983DOI Listing
January 2021

External Validation of an Algorithm to Predict Adjacent Musculoskeletal Infection in Pediatric Patients With Septic Arthritis.

J Pediatr Orthop 2020 Nov/Dec;40(10):e999-e1004

Department of Surgery, University of Auckland, Auckland.

Background: Septic arthritis (SA) remains a potentially morbid disease in the pediatric population. Magnetic resonance imaging (MRI) is the most sensitive tool for recognizing associated osteomyelitis and intramuscular abscess, but is a limited resource. The aim of this study is to externally validate a previously developed algorithm (Rosenfeld and colleagues) to predict adjacent infection in pediatric patients diagnosed with SA.

Methods: We identified 120 children under 16 with presumed SA presenting to a tertiary referral center between 2008 and 2018. Patients without confirmed SA, those with insufficient data, and patients who did not receive perioperative MRI were excluded, leaving 53 patients. The previous algorithm suggests that patient age (above 4 y), C-reactive protein (>8.9 mg/L), platelet count (<310×10cells/µL), duration of symptoms (>3 d), and absolute neutrophil count (>7.2×10cells/µL) are risk factors for adjacent infection, with 3 or more variables signifying a "positive" result. Comparing against the gold standard of MRI, the accuracy of the algorithm was validated in terms of sensitivity, specificity, likelihood ratio (LR), and positive and negative predictive value. Discrimination and calibration of this algorithm have been assessed using receiver operating curve analysis and calibration plots.

Results: The sensitivity and specificity of criteria from Rosenfeld algorithm were 73% and 44%, respectively. Receiver operating curve showed poor discrimination [area under the curve=0.54, confidence interval (CI): 0.26-0.83]. The positive predictive value was 55.9% and the negative predictive value was 63.1% with LR +1.23 (CI: 0.87-1.98) and LR -0.61 (CI 0.28-1.30). Only 53% of patients with 4 or more criteria had an adjacent infection on MRI. Examining our cohort, children with a positive MRI finding had higher mean C-reactive protein (77 vs. 122 mg/L, P=0.04) and were more likely to have waited >72 hours days between symptom onset and hospital presentation (P=0.03).

Conclusion: Although treatment algorithms are an attractive tool to guide clinicians and resource allocation, they need to take into account the local population characteristics before routine implementation.

Level Of Evidence: Level IV-retrospective cohort study.
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http://dx.doi.org/10.1097/BPO.0000000000001618DOI Listing
March 2021

An ammonite trapped in Burmese amber.

Proc Natl Acad Sci U S A 2019 06 13;116(23):11345-11350. Epub 2019 May 13.

Department of Geology and Atmospheric Science, Indiana University, Bloomington, IN 47405

Amber is fossilized tree resin, and inclusions usually comprise terrestrial and, rarely, aquatic organisms. Marine fossils are extremely rare in Cretaceous and Cenozoic ambers. Here, we report a record of an ammonite with marine gastropods, intertidal isopods, and diverse terrestrial arthropods as syninclusions in mid-Cretaceous Burmese amber. We used X-ray-microcomputed tomography (CT) to obtain high-resolution 3D images of the ammonite, including its sutures, which are diagnostically important for ammonites. The ammonite is a juvenile () and provides supporting evidence for a Late Albian-Early Cenomanian age of the amber. There is a diverse assemblage (at least 40 individuals) of arthropods in this amber sample from both terrestrial and marine habitats, including Isopoda, Acari (mites), Araneae (spiders), Diplopoda (millipedes), and representatives of the insect orders Blattodea (cockroaches), Coleoptera (beetles), Diptera (true flies), and Hymenoptera (wasps). The incomplete preservation and lack of soft body of the ammonite and marine gastropods suggest that they were dead and underwent abrasion on the seashore before entombment. It is most likely that the resin fell to the beach from coastal trees, picking up terrestrial arthropods and beach shells and, exceptionally, surviving the high-energy beach environment to be preserved as amber. Our findings not only represent a record of an ammonite in amber but also provide insights into the taphonomy of amber and the paleoecology of Cretaceous amber forests.
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http://dx.doi.org/10.1073/pnas.1821292116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6561253PMC
June 2019

Guided Growth: A Novel Treatment for Anterolateral Bowing of the Tibia.

J Pediatr Orthop 2017 Jul/Aug;37(5):e326-e328

Our Lady's Children's Hospital Crumlin, Dublin, Ireland.

Background: Tibial pseudoarthrosis is a source of considerable morbidity in children with neurofibromatosis. Preventing the progression of anterolateral bowing of the tibia (ALBT) to tibial pseudoarthrosis is difficult. The aim of this paper is to report the successful use of guided growth to prevent tibial pseudoarthrosis in a child with neurofibromatosis.

Methods: With local ethical approval, we reviewed the case notes and radiographs of a child with pronounced ALBT who was treated with guided growth to correct the deformity and prevent fracture.

Results: At 4-year follow-up guided growth has successfully corrected the deformity and prevented tibial pseudoarthrosis.

Conclusions: This is the first report of the use of guided growth to prevent the progression of ALBT to pseudoarthrosis of the tibia in a child with neurofibromatosis.

Level Of Evidence: Level IV.
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http://dx.doi.org/10.1097/BPO.0000000000000981DOI Listing
November 2017

Levels of Evidence in the Treatment of Slipped Capital Femoral Epiphysis: A Systematic Review.

Orthop Rev (Pavia) 2016 Jun 27;8(2):6303. Epub 2016 Jun 27.

Our Lady's Hospital Crumlin , Dublin, Ireland.

The primary aim of this study was to analyze the current level of evidence available on the surgical management of Slipped Capital Femoral Epiphysis (SCFE). Secondary aims were to correlate the level of evidence with the impact factor of the journal to evaluate the level of evidence over time, and to evaluate the geographic distribution of the studies. Therapeutic studies published in English between January 1991 and August 2014 that reported on SCFE were identified via electronic search was performed using the databases PubMed, EMBASE, and the Cochrane Library. The search terms used included: Slipped capital femoral epiphyses OR SCFE OR Slipped upper femoral epiphyses OR SUFE AND Management OR Treatment. Correlation between the level of evidence and the impact factor of the journal were analyzed together with linear regression models to reveal any significant trends over time. A total of 1516 studies were found, of which 321 were included in the final analysis. The most frequent study type was the case series (51.1%) followed by case reports (22.4%) and expert opinion (14.0%). Randomized control trial accounted for only 0.6%. The Journal of Pediatric Orthopedics (American) had the most studies (22.6%) and the highest number of level 2 (n=1) and level 3 (n=15) type evidence. There was no progression of level of evidence over time. There was no correlation between level of evidence and impact factor of journal. The majority of therapeutic studies on SCFE are of low level of evidence. High-level RCTs are difficult to perform in pediatric orthopedic surgery, however the management of SCFE would benefit from well-designed, multicenter, clinical RCTs to advance evidence-based practice.
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http://dx.doi.org/10.4081/or.2016.6303DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4933817PMC
June 2016

Progression of Hip Dysplasia in Mucopolysaccharidosis Type I Hurler After Successful Hematopoietic Stem Cell Transplantation.

J Bone Joint Surg Am 2016 Mar;98(5):386-95

Department of Pediatric Metabolic Diseases, Emma Children's Hospital and Amsterdam Lysosome Center "Sphinx," Academic Medical Center, Amsterdam, the Netherlands

Background: Dysostosis multiplex contributes substantially to morbidity in patients with Hurler syndrome (mucopolysaccharidosis type I Hurler phenotype [MPS I-H]), even after successful hematopoietic stem cell transplantation (HSCT). One of the hallmarks of dysostosis multiplex in MPS I-H is hip dysplasia, which often requires surgical intervention. We sought to describe in detail the course of hip dysplasia in this group of patients, as assessed by radiographic analysis, and to identify potential outcome predictors.

Methods: Longitudinal data were obtained from digitally scored pelvic radiographs of patients with MPS I-H using OrthoGon software for parameters including, but not limited to, the acetabular index, migration percentage, Smith ratio, and neck-shaft angle. Scoring was performed independently by two blinded observers. Additional information on genotype, enzyme replacement therapy pre-HSCT, donor chimerism, and enzyme activity post-HSCT were obtained. General trends and potential correlations were calculated with mixed-model statistics.

Results: Fifty-two patients (192 radiographs) were included in this analysis. Intraobserver and interobserver variation analysis showed an intraclass correlation coefficient ranging from 0.78 to 1.00. Among the twenty-one patients with follow-up beyond the age of five years, the acetabular index was in the range of severe hip dysplasia in up to 86% of the patients. Severe coxa valga was seen in 91% of the patients. Lateral and superior femoral displacement were highly prevalent, with the migration percentage outside the reference range in up to 96% of the patients. Finally, anterior pelvic tilt increased with age (p = 0.001). No correlations were identified between clinical parameters and radiographic findings.

Conclusions: Our study shows that progressive acetabular dysplasia as well as coxa valga and hip displacement are highly prevalent and progressive over time in patients with MPS I-H, despite successful HSCT. These data may provide essential natural history determinations for the assessment of efficacy of new therapeutic strategies aimed at improving skeletal outcomes in patients with MPS I-H.
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http://dx.doi.org/10.2106/JBJS.O.00601DOI Listing
March 2016

A Long-term Retrospective Evaluation of Functional and Radiographic Outcomes of Pediatric Hip Surgery in Hurler Syndrome.

J Pediatr Orthop 2016 Jan;36(1):25-8

Departments of *Orthopaedics †Haematology/Oncology §Metabolic Disease, Our Lady's Children's Hospital, Crumlin ‡Mater Misericordiae Hospital, Dublin, Ireland.

Background: After successful hematopoietic stem cell transplantation, maintaining function and mobility have become key goals in the management of patients with Hurler syndrome, (mucopolysaccharoidosis type 1H). The aim of this study was to establish the functional and radiologic outcomes after hip surgery in patients with this condition who had reached skeletal maturity.

Methods: We prospectively followed 13 mucopolysaccharoidosis type 1H patients with closed triradiate cartilages who had undergone hip surgery in a single institution (Our Lady's Children's Hospital, Crumlin) in early childhood, after successful hematopoietic stem cell transplantation. Functional assessment was performed using the Harris Hip Score. Acetabular and femoral head morphology were defined using a pelvic radiograph.

Results: The average age at follow-up was 18.6 years (range, 13.2 to 23.8 y). The average length of follow-up from surgical intervention was 14.6 years (range, 10.3 to 21.6 y). The average Harris Hip Score at follow-up was 61.0 (range, 19 to 91). At follow-up, 4 patients were either wheelchair bound or required a walking frame to mobilize in the community. At follow-up, all hips were in-joint with an average center edge angle of 37.7 degrees (range, 0 to 63 degrees). All hips displayed characteristic medial flattening of the femoral head. Ten hips (of 26 hips) showed radiologic degenerative changes with loss of joint space <2 mm.

Conclusions: Despite the surgical provision of stable well-covered hips, active intervention did not prevent the development of radiologic deterioration and clinically significant hip arthritis. We recommend that pediatric hip surgery in Hurler syndrome be designed with the possibility of early hip replacement in mind.

Level Of Evidence: Level III.
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http://dx.doi.org/10.1097/BPO.0000000000000385DOI Listing
January 2016

A quality analysis of internet-based information on common hand pathology.

J Plast Reconstr Aesthet Surg 2015 Mar 29;68(3):441-2. Epub 2014 Oct 29.

Department of Orthopaedic Surgery, Cappagh National Orthopaedic Hospital, Dublin, Ireland; Department of Plastic and Reconstructive Surgery, Mater Misericodiae Hospital, Dublin, Ireland.

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http://dx.doi.org/10.1016/j.bjps.2014.10.033DOI Listing
March 2015

Locking plate fixation with and without inferomedial screws for proximal humeral fractures: a biomechanical study.

J Orthop Surg (Hong Kong) 2014 Aug;22(2):190-4

Department of Orthopaedic Research, Royal College of Surgeons, Dublin, Ireland.

PURPOSE. To compare the efficacy of locking plate fixation with and without inferomedial screws in maintaining the reduction of a proximal humeral fracture. METHODS. 22 synthetic humerus models were used. A standardised 3-part proximal humeral fracture with a 4-mm wedge segment was created and fixed with a locking plate and screws with (n=11) and without (n=11) inferomedial screws. The intrafragmentary motion of the construct at 250, 500, 750, and 1000 cycles of 532 N loading, and the load to failure of the 2 groups were compared. RESULTS. Locking plate fixation with inferomedial screws reduced the mean intrafragmentary motion in all cycles (p<0.01) and increased the load to failure (1452 N vs. 1159 N, p<0.001), compared to fixation without inferomedial screws. CONCLUSION. Additional inferomedial screws provide medial column support for fracture healing. This may reduce intrafragmentary motion and thus implant complications resulting from varus malalignment such as screw perforation or loss of reduction.
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http://dx.doi.org/10.1177/230949901402200215DOI Listing
August 2014

Effect of calcium triphosphate cement on proximal humeral fracture osteosynthesis: a cadaveric biomechanical study.

J Orthop Surg (Hong Kong) 2013 Aug;21(2):173-7

Department of Orthopaedic Research, Royal College of Surgeons, Dublin, Ireland.

PURPOSE. To evaluate the effect of filling a central humeral bone void with calcium triphosphate cement on the strength and stability of an osteosynthesis in elderly cadavers. METHODS. 14 fresh cadaveric shoulder specimens obtained from 11 donors (mean age, 91.5 years; mean body weight, 61 kg) were divided into 2 age- and sex-matched groups. A standardised 3-part proximal humeral fracture with a central bone void was created in each specimen. Each specimen was reduced and fixed with a locking plate. In half the specimens the central bone void was packed with calcium triphosphate cement. The intra-fragmentary motion and the load and mode of failure were recorded. RESULTS. Respectively in the test group and controls, the intra-fragmentary motion was 1.0 and 6.4 mm, and the peak displacement at the 500 N load was 1.8 and 9.1 mm. The Cohen's d was 1.6 to 2.7 for all load steps, indicating a large effect of the calcium triphosphate cement on strength and stability. The mean difference in the failure load was 300 N (p<0.05). CONCLUSION. Construct stability and failure load improved significantly when the central humeral bone void was filled with calcium triphosphate cement.
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http://dx.doi.org/10.1177/230949901302100211DOI Listing
August 2013

Effect of calcium triphosphate cement on proximal humeral fracture osteosynthesis: a finite element analysis.

J Orthop Surg (Hong Kong) 2013 Aug;21(2):167-72

Department of Orthopaedic Research, Royal College of Surgeons, Dublin, Ireland.

PURPOSE. To measure the effect of void-filling calcium triphosphate cement on the loads at the implant-bone interface of a proximal humeral fracture osteosynthesis using a finite element analysis. METHODS. Finite element models of a 3-part proximal humeral fracture fixed with a plate with and without calcium triphosphate cement augmentation were generated from a quantitative computed tomography dataset of an intact proximal humerus. Material properties were assigned to bone fragments using published expressions relating Young's modulus to local Hounsfield number. Boundary conditions were then applied to the model to replicate the physiological loads. The effect of void-filling calcium triphosphate cement was analysed. RESULTS. When the void was filled with calcium triphosphate cement, the pressure gradient of the bone surrounding the screws in the medial fracture fragment decreased 97% from up to 21.41 to 0.66 MPa. Peak pressure of the fracture planes decreased 95% from 6.10 to 0.30 MPa and occurred along the medial aspect. The mean stress in the screw locking mechanisms decreased 78% from 71.23 to 15.92 MPa. The angled proximal metaphyseal screw had the highest stress. CONCLUSION. Augmentation with calcium triphosphate cement improves initial stability and reduces stress on the implant-bone interface.
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http://dx.doi.org/10.1177/230949901302100210DOI Listing
August 2013

Foot and ankle abnormalities in the Hurler syndrome: additions to the phenotype.

J Pediatr Orthop 2013 Jul-Aug;33(5):558-62

Our Lady's Children's Hospital, Crumlin, Dublin, Ireland.

Background: After successful hematopoietic stem cell transplantation maintaining function and mobility has become the key goal in the management of patients with mucopolysaccharoidosis type 1 (MPS-1). We detail the foot and ankle pathology in 18 patients with MPS-1 managed in our unit.

Methods: Functional assessment was performed using the Oxford Foot and Ankle Questionnaire for children (OxAFQ-C). Morphologic assessment was performed by means of a mirrored foot photograph box, the Foot Posture Index (FPI), and clinical photography. Standardized radiologic investigations were sought when clinically warranted. Average lateral talus-first metatarsal angle, anteroposterior and lateral talocalcaneal angles, and lateral distal tibial angle (LDTA) were determined.

Results: The average patient-reported OxAFQ-C score was 44.7 (range, 10 to 60). The average proxy-reported OxAFQ-C score was 45.7 (range, 11 to 60). Ten of the 18 patients wore customized footwear. Of the 36 feet examined 11 were found scored as "highly pronated" (FPI>+9), 12 feet had a "pronated posture" (FPI +6 to +9), and 13 feet were found to have a "normal posture" (FPI 0 to +5). Thirteen of the 18 (72%) patients studied had curly toes. The average talus-first metatarsal angle recorded was 10.7 degrees (range, -7 to 30 degrees). The average lateral and anteroposterior talocalcaneal angles were 45.8 degrees (range, 16 to 62 degrees) and 31 degrees (range, 1 to 51 degrees), respectively. The average LDTA was found to be 70.6 degrees (range, 48 to 82 degrees). A single-sample Student t test shows significant divergence of measured LDTA, OxAFQ-C, and FPI from normal populations (P<0.005).

Conclusions: MPS-1 is associated with a significant degree of foot and ankle pathology that has not been previously described. We found a high incidence of curly toes, ankle valgus, functional foot, and ankle disability and a requirement for customized footwear among our cohort. We recommend that careful assessment of foot and ankle pathology should be routine in the interdisciplinary management of patients with MPS-1.

Level Of Evidence: Level III.
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http://dx.doi.org/10.1097/BPO.0b013e318280a124DOI Listing
February 2014

Catastrophic spinal injury after minor fall in a patient with ankylosing spondylitis.

West J Emerg Med 2013 Mar;14(2):146

Department of Emergency Medicine, Mater Misericordiae Hospital, Dublin, Ireland.

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http://dx.doi.org/10.5811/westjem.2012.10.13903DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3628463PMC
March 2013

Investigation of metallic and carbon fibre PEEK fracture fixation devices for three-part proximal humeral fractures.

Med Eng Phys 2013 Jun 16;35(6):712-22. Epub 2012 Sep 16.

Department of Mechanical and Biomedical Engineering, National University of Ireland, Galway, Ireland.

A computational investigation of proximal humeral fracture fixation has been conducted. Four devices were selected for the study; a locking plate, intramedullary nail (IM Nail), K-wires and a Bilboquet device. A 3D model of a humerus was created using a process of thresholding based on the grayscale values of a CT scan of an intact humerus. An idealised three part fracture was created in addition to removing a standard volume from the humeral head as a representation of bone voids that occur as a result of the injury. All finite element simulations conducted represent 90° arm abduction. Simulations were conducted to investigate the effect of filling this bone void with calcium phosphate cement for each device. The effect of constructing devices from carbon fibre polyetheretherketone (CFPEEK) was investigated. Simulations of cement reinforced devices predict greater stability for each device. The average unreinforced fracture line opening (FLO) is reduced by 48.5% for metallic devices with a lesser effect on composite devices with FLO reduced by 23.6%. Relative sliding (shear displacement) is also reduced between fracture fragments by an average of 58.34%. CFPEEK device simulations predict reduced stresses at the device-bone interface.
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http://dx.doi.org/10.1016/j.medengphy.2012.07.016DOI Listing
June 2013

Munro sets the agenda.

Authors:
Jim Kennedy

J Fam Health Care 2012 Mar-Apr;22(2):36-7

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July 2012

Locking plate fixation for proximal humerus fractures.

Orthopedics 2012 Feb 17;35(2):e250-4. Epub 2012 Feb 17.

Department of Orthopaedic Surgery, Cappagh National Orthopaedic Hospital, Dublin, Ireland.

Locking plates are increasingly used to surgically treat proximal humerus fractures. Knowledge of the bone quality of the proximal humerus is important. Studies have shown the medial and dorsal aspects of the proximal humeral head to have the highest bone strength, and this should be exploited by fixation techniques, particularly in elderly patients with osteoporosis. The goals of surgery for proximal humeral fractures should involve minimal soft tissue dissection and achieve anatomic reduction of the head complex with sufficient stability to allow for early shoulder mobilization. This article reviews various treatment options, in particular locking plate fixation. Locking plate fixation is associated with a high complication rate, such as avascular necrosis (7.9%), screw cutout (11.6%), and revision surgery (13.7%). These complications are frequently due to the varus deformation of the humeral head. Strategic screw placement in the humeral head would minimize the possibility of loss of fracture reduction and potential hardware complications. Locking plate fixation is a good surgical option for the management of proximal humerus fractures. Complications can be avoided by using better bone stock and by careful screw placement in the humeral head.
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http://dx.doi.org/10.3928/01477447-20120123-41DOI Listing
February 2012

The Hounsfield value for cortical bone geometry in the proximal humerus--an in vitro study.

Skeletal Radiol 2012 May 20;41(5):557-68. Epub 2011 Sep 20.

Investigations Carried Out at Anatomy Lab, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin and Sports Surgery Clinic, Santry, Dublin, Ireland.

Introduction: Fractures of the proximal humerus represent a major osteoporotic burden. Recent developments in CT imaging have emphasized the importance of cortical bone thickness distribution in the prevention and management of fragility fractures. We aimed to experimentally define the CT density of cortical bone in the proximal humerus for building cortical geometry maps.

Methods: With ethical approval, we used ten fresh-frozen human proximal humeri. These were stripped of all soft tissue and high-resolution CT images were then taken. The humeral heads were then subsequently resected to allow access to the metaphyseal area. Using curettes, cancellous bone was removed down to hard cortical bone. Another set of CT images of the reamed specimen was then taken. Using CT imaging software and a CAD interface, we then compared cortical contours at different CT density thresholds to the reference inner cortical contour of our reamed specimens. Working with 3D model representations of these cortical maps, we were able to accurately make distance comparison analyses based on different CT thresholds.

Results: We could compute a single closest value at 700 HU. No difference was found in the HU-based contours generated along the 500-900 HU pixels (p = 1.000). The contours were significantly different from those generated at 300, 400, 1,000, and 1,100 HU.

Conclusions: A Hounsfield range of 500-900 HU can accurately depict cortical bone geometry in the proximal humerus. Thresholding outside this range leads to statistically significant inaccuracies. Our results concur with a similar range reported in the literature for the proximal femur. Knowledge of regional variations in cortical bone thickness has direct implications for basic science studies on osteoporosis and its treatment, but is also important for the orthopedic surgeon since our decision for treatment options is often guided by local bone quality.
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http://dx.doi.org/10.1007/s00256-011-1255-7DOI Listing
May 2012

A cadaveric model for suprascapular nerve injury during glenoid component screw insertion in reverse-geometry shoulder arthroplasty.

J Shoulder Elbow Surg 2011 Dec 20;20(8):1323-7. Epub 2011 May 20.

Department of Orthopaedic Surgery, Cappagh National Orthopaedic Hospital, Dublin, Ireland.

Background: Reverse-geometry shoulder replacement requires fixation of a baseplate (called a metaglene) to the glenoid, to which a convex glenosphere is attached. Most systems use screws to achieve this fixation. The suprascapular nerve passes close to the glenoid and is known to be at risk of injury when devices and sutures are inserted into the glenoid. We investigate the risk posed to the suprascapular nerve by placement of metaglene fixation screws.

Materials And Methods: Ten cadaveric shoulder specimens were used. A metaglene was inserted and fixed by use of 4 screws. The suprascapular nerve was dissected and its branches identified. The screw tips and their proximity to the nerve and branches were identified and recorded.

Results: The superior and posterior screws posed the most risk to the suprascapular nerve. The nerve was engaged by the posterior screw on 4 occasions and was within 5 mm of the nerve or a branch of it in 5 others. The superior screw was extraosseous on 4 occasions, making contact with the nerve in 3 of those 4 specimens and being within 2 mm of it in the fourth specimen.

Conclusion: Metaglene fixation with screws poses a significant risk to the suprascapular nerve. Caution should be used when inserting the posterior and superior screws in particular. Short locking screws may allow adequate fixation while minimizing the risk of neurologic injury.
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http://dx.doi.org/10.1016/j.jse.2011.02.014DOI Listing
December 2011

Free-hand versus novel specialised jig guidance for the passing of intramedullary wires in olecranon fracture fixation: a comparative study.

Injury 2011 Apr 30;42(4):343-6. Epub 2010 Mar 30.

Department of Trauma and Orthopaedic Surgery, Cappagh National Orthopaedic Hospital, Dublin 11, Ireland.

The treatment of olecranon fractures frequently involves the use of tension-band fixation. Although associated with high union rates, this method has a high incidence of morbidity associated with soft tissue compromise and limitation of range of movement requiring frequent re-operation for removal of metal. We describe the use of a simple jig to ensure intramedullary placement of longitudinal K-wires and compare the accuracy of placement of Kirschner (K)-wires using this device with the traditional free-hand method. We found the distance from the centre of the medullary canal, the range and standard deviations of K-wire positions to be significantly more precise when the jig was used. This has applications for the use of the device, both with standard metallic radio-opaque wires and potentially with bio-absorbable pins.
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http://dx.doi.org/10.1016/j.injury.2010.02.034DOI Listing
April 2011

Data briefing. Quality measures obscure real picture.

Authors:
Jim Kennedy

Health Serv J 2008 Sep:19

TCN.

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September 2008

A prospective, randomized trial of 3 or 14 days of ciprofloxacin treatment for acute urinary tract infection in patients with spinal cord injury.

Clin Infect Dis 2004 Sep 13;39(5):658-64. Epub 2004 Aug 13.

Department of Medical Microbiology, University of Manitoba, Winnipeg, Canada.

Background: Urinary tract infection (UTI) is common among patients with spinal cord injury. The optimal duration of treatment for symptomatic UTI has not been determined.

Methods: A randomized, double-blind, placebo-controlled trial compared 3-day and 14-day regimens of ciprofloxacin, 250 mg twice daily, for the treatment of acute UTI in patients with spinal cord injury. Patients with pyelonephritis, struvite stones, hydronephrosis, or long-term indwelling catheters were excluded from the trial.

Results: Sixty patients with spinal cord injury were enrolled in the trial, with 30 patients assigned to each study arm. The most common infecting organisms were Klebsiella species (30%), Enterococcus species (22%), and Escherichia coli (22%); 33% of the infections were polymicrobial. Microbiological cure at long-term follow-up was significantly better among patients who received therapy for 14 days than among patients who received therapy for 3 days. By 6 weeks of follow-up, microbiological relapse (in 11 [37%] of 30 patients vs. 2 [7%] of 30 patients; 95% confidence interval [CI], 1.38-3.18; P=.01) and symptomatic relapse (in 7 [23%] 30 patients vs. 0 of 30 patients; 95% CI, 1.69-3.13; P=.01) both occurred more frequently in patients treated for 3 days. Reinfection occurred with similar frequency in patients in the 2 study arms. Six of 7 evaluable patients with treatment failure had a fluoroquinolone-resistant organism isolated at enrollment.

Conclusions: For patients with spinal cord injury, treatment of acute symptomatic UTI for 14 days leads to improved clinical and microbiological outcomes, compared with short-course therapy.
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http://dx.doi.org/10.1086/423000DOI Listing
September 2004