The Evaluation of Serum Metal Ion Levels and Metallosis in Graduated Patients With Magnetically Controlled Growing Rods.

BACKGROUND: Magnetically controlled growing rods (MCGR) aim to control curve progression while limiting surgical burden in children with early-onset scoliosis. Systemic and local distribution of metal debris has been documented in children with spinal implants. The aim of the study was to assess serum metal ion levels and local metal debris-related changes at the conclusion of MCGR treatment. METHODS: Between February 2019 and September 2022, all patients who had a conversion to definitive fusion at the completion of MCGR treatment in our institution were invited to participate in this study. Consenting patients had serum metal ion levels drawn (titanium, cobalt, and chromium) and histologic analyses of peri-implant tissue samples. RESULTS: We enrolled 24 children who underwent definitive fusion post-MCGR treatment for early-onset scoliosis. The average age at definitive fusion was 13.3 years (range: 11 to 17 y). The average length of MCGR treatment was 4.8 years (range: 1.5 to 6.8 y). At the end of the MCGR treatment, 23 (96%) patients had elevated serum metal ion levels. Mean serum titanium levels were 165.4 nmol/L (range: 30 to 390 nmol/L), mean serum cobalt levels were 4.6 nmol/L (range: 1.2 to 14 nmol/L), and mean serum chromium levels were 14 nmol/L (range: 2.4 to 30 nmol/L). Peri-implant soft tissue histologic analysis demonstrated local metal debris and foreign body reactions in all patients. CONCLUSIONS: At the completion of MCGR treatment, the majority of patients demonstrate elevated serum metal ion levels and local metal debris-related peri-implant soft tissue changes. Although there is no current literature to suggest these findings are harmful, further research as to the clinical significance is required. LEVEL OF EVIDENCE: Level IV.

Weight Gain and Nutritional Improvement After Magnetically Controlled Growing Rod Surgery in Early-Onset Scoliosis: A Single Centre Analysis of 68 Patients.

BACKGROUND: Early-onset scoliosis (EOS) is frequently associated with complex spine and chest wall deformities that may lead to severe cardiopulmonary impairment and malnutrition. The aim of this study is to evaluate the change in the nutritional status of EOS patients after treatment with magnetically controlled growing rod instrumentation (MCGR) in a single center. METHODS: We prospectively collected data of patients treated with MCGR for EOS in a single center. Exclusion criteria were <2 years' follow-up and incomplete weight-for-age Z-scores (WAZ) data. Preoperative and postoperative WAZ, radiographic parameters, including major coronal curve, kyphosis angle, space available for lung ratios, thoracic height, and unplanned returns to the operating room (UPROR), were analyzed. SD and 95% Confidence intervals (CI) are presented with means. RESULTS: Sixty-eight patients (37 males/31 females) were included. The mean age at surgery was 8.2 years (SD 2.8, range 1.8-14.2), and the mean follow-up time was 3.8 years (SD 1.0, range 2.1-6.8). The study population was categorized by the primary diagnosis as follows: 23 neuromuscular, 18 idiopathic, 15 congenital, and 12 syndromic patients. The major coronal curve improved between the preoperative and latest visits by 40% ( P <0.005, SD 27, CI 33-47), while the space available for lung ratios improved by 8% ( P <0.005, SD 13, CI 5-12). Thoracic height increased by 25% ( P <0.005, SD 13, CI 22-28), and kyphosis angle decreased by 25% ( P <0.005, SD 26, CI 9-39). Eighteen patients (27%) required a total of 53 UPRORs. WAZ improved significantly between the preoperative and the latest follow-up ( P =0.005). Regression analysis showed WAZ improvements were most significant in the underweight patients and the Idiopathic or Syndromic EOS patients. UPROR was not associated with deterioration in WAZ. CONCLUSIONS: Treatment of EOS patients with MCGR resulted in an improvement in nutritional status, as evidenced by the significant increase in WAZ. Underweight, Idiopathic and Syndromic EOS patients, and those who required UPROR all had significant improvement in their WAZ with MCGR treatment. LEVEL OF EVIDENCE: Therapeutic Study-Level II.

Age as a predictor of additional surgeries following initial closed reduction for children with developmental dysplasia of the hip: the 10-year experience of a national paediatric orthopaedic unit.

BACKGROUND AND PURPOSE: Dislocated and unstable hip joints which do not stabilize in an orthosis in the neonatal period require operative intervention to achieve a stable concentric joint. The aim of this study is to assess the requirement for further operative intervention in patients who have undergone successful closed reduction to treat developmental dysplasia of the hip (DDH). METHODS: We identified all patients who had undergone closed reduction of an unstable hip joint at our institution within 10 years, with further identification of patients who underwent a second procedure. We used logistic regression to evaluate correlation between age at closed reduction and the probability of secondary procedures. RESULTS: A total of 694 patients (84.5% females) who underwent a closed reduction in the study period were identified. 235 were excluded (patients with underlying genetic conditions, neuromuscular disorders, syndromic disorders). 250 patients had closed reductions only. 209 patients (45.5%) had at least 1 secondary procedure after their initial closed reduction. In multivariable analysis, female gender (OR 0.310; 95% CI, 0.108-0.885; p = 0.029) and patients aged ⩽12 months at the time of first surgery (OR 0.055; 95% CI, 0.007-0.423; p = 0.005) independently predicted being less likely to require a second surgery for their DDH. DISCUSSION: In conclusion, we found that a significant proportion of children (45.5%) who underwent closed reduction of a dislocated hip required additional surgical intervention in early childhood. Our data show that those children who undergo later closed reduction of a dislocated hip in DDH after 12 months of age, and male infants, have a significantly higher incidence of additional surgical intervention.

Children's Hip Predictive (CHiP) Score: A Triage Tool for Hip Dislocation in Children Referred With Suspected Hip Dysplasia.

BACKGROUND: A fundamental tenent of treating developmental dysplasia of the hip is to identify patients with dislocated hips early so as to avoid the long-term sequelae of late diagnosis. The aim of this study was to develop a readily useable triage tool for patients with suspected hip dislocation, based on the clinical history and examination findings of the referring practitioner. METHODS: All primary care referrals (n=934) over a 3-year period for suspected developmental dysplasia of the hip to a tertiary pediatric center were evaluated. Defined parameters with respect to history and clinical examination were evaluated. Multivariable logistic regression was used to establish predictors of hip dislocation, and from this a predictive model was derived which incorporated significant predictors of dislocation. An illustrative nomogram translated this predictive model into a usable numerical scoring system called the Children's Hip Prediction score, which estimates probability of hip dislocation. RESULTS: There were 97 dislocated hips in 85 patients. The final predictive model included age, sex, family history, breech, gait concerns, decreased abduction, leg length discrepancy, and medical/neurological syndrome. The area under receiver operating curve for the model is 0.761. A Children's Hip Prediction score of≥5 corresponds to a sensitivity of 76.3% and a score of≥15 has a specificity of 97.8%, corresponding to an odds ratio of 27.3 for increased risk of dislocation. CONCLUSION: We found that a novel clinical prediction score, based on readily available history and examination parameters strongly predicted risk of dislocations in hip dysplasia referral. It is hoped that this tool could be utilized to optimize resource allocation and may be of particular benefit in less well-resourced health care systems. LEVEL OF EVIDENCE: Level II.

Vitamin D levels in Irish children with fractures: A prospective case-control study with 5 year follow-up.

INTRODUCTION: Twenty-five-hydroxy-vitamin D3 (25-OH-vit D) is a prohormone that is essential for normal calcium homeostasis and bone metabolism. Understanding its role is an important component of the proper care of the pediatric orthopaedic patient. The aim of this study was to determine whether children in Ireland with fractures have increased prevalence of 25-OH-Vit D deficiency compared with age matched controls and to ascertain the relationship between a low 25-OH-vit D level and the incidence of fractures in Irish children. We hypothesised that children presenting to our centre following a fracture would have significantly lower 25-OH-vit D. METHODS: A prospective case-control study at a large urban tertiary referral academic hospital located in Dublin, Ireland was completed over a 14 month period from June 2014 to August 2015. A total of 116 subjects, distributed as cases (n = 58) and controls (n = 58) were included in this study. Whole blood (10 ml) was taken in two serum bottles from each patient. Serum 25-hydroxy-vitamin D3 levels were measured. An age matched control group was generated from other children attending the hospital, who also had vitamin D levels measured for different clinical reasons. We followed up both the fracture and control group for the next 5 years to assess the repeat fracture rate. RESULTS: Fifty-eight patients with a fracture requiring operative intervention, were included in the study. Statistical analysis was performed comparing to 58 age and sex-matched controls. The mean vitamin D level for the fracture group was 63.2 nmol/L (SD = 27.3), which was higher than the mean of the controls (62.5 nmol/L) (SD = 21.3) (p = 0.86), but this difference was found not to be statistically significant in unadjusted analysis. There was no statistically significant difference in the number of patients classified with low serum Vitamin D levels (<50 nmolL), with the fracture group consisting of 22 (37.9%) patients, and the control group of 17 patients (29.3%) (p = 0.33) with a level below 50 nmol/L. At five-year follow-up, 11 of the 58 patients (18.9%) in the fracture group went on to have a further fracture compared with eight patients (13.7%) from the control group. Out of these 11 from the fracture group five (45.45%) had been found to have a low serum 25-OH-Vit D level five years previously. Out of the eight controls that presented with a fracture within the five-year period, 3 (37.5%) had had a low vitamin D level at the origin of this study. CONCLUSION: The results of this study show that children presenting to our institution with low energy fractures have a prevalence of 38% 25-hydroxy-vitamin D deficiency. This study included children from age 1 to 16 primarily Caucasian encompassing all fracture types resulting from accidental trauma. Our findings suggest that in an Irish pediatric population vitamin D status may impact fracture risk with more than one-third being deficient in this review.

One and done? Outcomes from 3961 patients managed via a virtual fracture clinic pathway for paediatric fractures.

PURPOSE: The aim of this paper is to describe our experience with a virtual fracture management pathway in the setting of a paediatric trauma service. METHODS: All patients referred to the virtual fracture clinic service from the Paediatric Emergency Department (PED) were prospectively collected. Outcome data of interest (patients discharged, referred for urgent operative treatment, referred back to emergency department for further evaluation, referred for face-to-face clinical assessment and all patients who re-presented on an unplanned basis for further management of the index injury) were compiled and collated. Cost analysis was performed using established costing for a virtual fracture clinic within the Irish Healthcare System. RESULTS: There were a total of 3961 patients referred to the virtual fracture clinic from the PED. Of these, 70% (n = 2776) were discharged. In all, 26% (n = 1033) were referred to a face-to-face appointment. Of discharged patients, 7.5% (n = 207) required an unplanned face-to-face evaluation. A total of 0.1% (n = 3) subsequently required operative treatment relating to their index injury. Implementation of the virtual fracture clinic model generated calculated savings of €254 120. CONCLUSION: This prospective evaluation has demonstrated that a virtual fracture clinic pathway for minor paediatric trauma is safe, effective and brings significant cost savings. LEVEL OF EVIDENCE: II.

The use of three rods in correcting severe scoliosis.

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.

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

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;40:1335-1340. © 2021 SETAC.

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

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.

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

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.

An ammonite trapped in Burmese amber.

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 Puzosia (Bhimaites) 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.

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

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.

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

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.

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

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.

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

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.

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

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.

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

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.

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

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.

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

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.