Sleeve fracture of the patella in children

PURPOSE

To report the diagnosis, treatment, and outcomes of sleeve patellar fractures in children.

METHODS

Records of a consecutive series of patients with sleeve patellar fractures were retrospectively reviewed.

RESULTS

Of the 11 children (8 boys and 3 girls; mean age, 12 years), 6 had minimally displaced fractures (1-2 mm) and were managed by cylindrical plaster of Paris immobilisation, whereas the other 5 with severely displaced fractures underwent open reduction with tension band wiring. The mean follow-up period was 10 (range, 3-36) months. All patients obtained full extension of the knee except one (with an extension lag of 10 degrees). No patient complained of pain or discomfort of the involved knee.

CONCLUSION

Sleeve patellar fractures in children are uncommon. Diagnosis can be missed, especially in those with a very small avulsed bony fragment. For undisplaced fracture, conservative management can achieve good results. For severely displaced fractures, early surgical intervention is effective.

Molecular basis of fibrin clot elasticity

Blood clots must be stiff to stop hemorrhage yet elastic to buffer blood's shear forces. Upsetting this balance results in clot rupture and life-threatening thromboembolism. Fibrin, the main component of a blood clot, is formed from molecules of fibrinogen activated by thrombin. Although it is well known that fibrin possesses considerable elasticity, the molecular basis of this elasticity is unknown. Here, we use atomic force microscopy (AFM) and steered molecular dynamics (SMD) to probe the mechanical properties of single fibrinogen molecules and fibrin protofibrils, showing that the mechanical unfolding of their coiled-coil alpha helices is characterized by a distinctive intermediate force plateau in the systems' force-extension curve. We relate this plateau force to a stepwise unfolding of fibrinogen's coiled alpha helices and of its central domain. AFM data show that varying pH and calcium ion concentrations alters the mechanical resilience of fibrinogen. This study provides direct evidence for the coiled alpha helices of fibrinogen to bring about fibrin elasticity.

Management outcome and the role of manipulation in slipped capital femoral epiphysis

PURPOSE

To examine and compare treatment outcomes for slipped capital femoral epiphysis (SCFE).

METHODS

24 patients with acute or acute-on-chronic SCFE underwent preoperative traction, 13 of them followed by in situ screw fixation (group A), and the remaining 11, manipulation with screw fixation (group B). Their treatment outcomes (according to the Aadalen criteria) and complications were compared.

RESULTS

There were 2 treatment failures and one poor outcome in patients with acute SCFE (2 had avascular necrosis and one had slight pain with mild limitation of hip movement). The risk of developing avascular necrosis was significantly higher in patients with acute rather than acute-on-chronic or chronic slips. No significant differences were evident between groups A and B with regard to age, sex, ethnicity, outcomes, and preoperative and postoperative changes in the Southwick headshaft angle.

CONCLUSION

Patients with acute or acute-on-chronic SCFE can be safely managed with straight-leg traction for up to 6 days, followed by in situ screw fixation without manipulation. Manipulation is not recommended in such slips, due to a higher avascular necrosis risk.

Secondary and tertiary structure elasticity of titin Z1Z2 and a titin chain model

The giant protein titin, which is responsible for passive elasticity in muscle fibers, is built from approximately 300 regular immunoglobulin-like (Ig) domains and FN-III repeats. While the soft elasticity derived from its entropic regions, as well as the stiff mechanical resistance derived from the unfolding of the secondary structure elements of Ig- and FN-III domains have been studied extensively, less is known about the mechanical elasticity stemming from the orientation of neighboring domains relative to each other. Here we address the dynamics and energetics of interdomain arrangement of two adjacent Ig-domains of titin, Z1, and Z2, using molecular dynamics (MD) simulations. The simulations reveal conformational flexibility, due to the domain-domain geometry, that lends an intermediate force elasticity to titin. We employ adaptive biasing force MD simulations to calculate the energy required to bend the Z1Z2 tandem open to identify energetically feasible interdomain arrangements of the Z1 and Z2 domains. The finding is cast into a stochastic model for Z1Z2 interdomain elasticity that is generalized to a multiple domain chain replicating many Z1Z2-like units and representing a long titin segment. The elastic properties of this chain suggest that titin derives so-called tertiary structure elasticity from bending and twisting of its domains. Finally, we employ steered molecular dynamics simulations to stretch individual Z1 and Z2 domains and characterize the so-called secondary structure elasticity of the two domains. Our study suggests that titin's overall elastic response at weak force stems from a soft entropic spring behavior (not described here), from tertiary structure elasticity with an elastic spring constant of approximately 0.001-1 pN/A and, at strong forces, from secondary structure elasticity.

An analysis of soft tissue allograft anterior cruciate ligament reconstruction in a rabbit model: a short-term study of the use of mesenchymal stem cells to enhance tendon osteointegration

BACKGROUND

Soft tissue allografts are essential for revision and multiple ligament surgeries in the knee, where donor-site morbidity is an issue. However, the use of allografts is associated with a higher failure rate of osteointegration. Mesenchymal stem cells (MSCs) are investigated as potential agents to enhance bone tunnel and tendon healing.

PURPOSE

This study was conducted to analyze the effect of coating allografts with MSCs on the quality and rate of osteointegration at the allograft tendon and bone interface, and the biomechanical properties of these enhanced anterior cruciate ligament (ACL) grafts compared with controls.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Bilateral ACL reconstructions using Achilles tendon allografts were performed in 36 rabbits. On 1 limb, the graft was coated with autogenous MSCs in a fibrin glue carrier, while the contralateral limb served as a control with no MSCs. The reconstructions were assessed histologically and biomechanically at 2, 4, and 8 weeks.

RESULTS

At 8 weeks, histologic analysis of the controls revealed the development of mature scar tissue resembling Sharpey fibers spanning the tendon-bone interface. In contrast, the MSC-enhanced reconstructions showed a mature zone of fibrocartilage blending from bone to the allograft, strongly resembling a normal ACL insertion. On biomechanical testing, the MSC-enhanced grafts had significantly higher load-to-failure rates than controls. However, the stiffness and Young's modulus were lower in the treatment group.

CONCLUSIONS

The application of MSCs at the allograft tendon-bone interface during ACL reconstruction results in the development of an intervening zone of fibrocartilage. The use of MSCs to enhance allograft osteointegration is a novel method offering the potential of more physiologic and earlier healing, although further investigation must be conducted to improve the biomechanical strength.

CLINICAL RELEVANCE

Mesenchymal stem cells can improve the biologic properties of soft tissue allograft healing. Combined with the decrease in donor-site morbidity, allografts are a viable choice for the sports medicine surgeon.

Traction and spica casting for closed femoral shaft fractures in children

PURPOSE

To evaluate the treatment outcome of skin traction followed by spica casting for closed femoral shaft fractures in children.

METHODS

Between September 1997 and December 2001 inclusive, outcomes of 63 children aged one month to 15 (mean, 5.3) years with closed femoral shaft fractures managed with skin traction and spica casting were reviewed. Depending on age, patients were kept in traction from 2 to 15 (median, 9) days, then in spica casts for 2 to 8 (median, 5) weeks.

RESULTS

Bony union took 3 to 12 (median, 6) weeks. There were no malunion, nonunion, or rotational deformities. Nor were there any significant limb length discrepancies, pressure sores, or nerve palsies. On no occasion was a spica cast removed and reapplied for loss of fracture reduction. At final follow-up, limb length discrepancy was noted in 14 (22%) of the patients, but none had a discrepancy of greater than 1.5 cm or a short-legged gait.

CONCLUSION

Skin traction followed by spica casting for closed femoral shaft fractures in children is safe, cost-effective and associated with a low complication rate. It is effective in children below 5 years of age and no less effective in older children, except in instances of open fracture, multiple fractures, or older children with large statures, which conditions render them intolerant to spica casts.

Mechanical strength of the titin Z1Z2-telethonin complex

Using molecular dynamics simulations, we have explored the mechanical strength of the titin Z1Z2-telethonin complex, namely, its ability to bear strong forces such as those encountered during passive muscle stretch. Our results show that not only does this complex resist considerable mechanical force through beta strand crosslinking, suggesting that telethonin is an important component of the N-terminal titin anchor, but also that telethonin distributes these forces between its two joined titin Z2 domains to protect the proximal Z1 domains from bearing too much stress. Our simulations also reveal that without telethonin, apo-titin Z1Z2 exhibits significantly decreased resistance to mechanical stress, and that the N-terminal segment of telethonin (residues 1-89) does not exhibit a stable fold conformation when it is unbound from titin Z1Z2. Consequently, our study sheds light on a key but little studied architectural feature of biological cells-the existence of strong mechanical links that glue separate proteins together.

Molecular mechanisms of cellular mechanics

Mechanical forces play an essential role in cellular processes as input, output, and signals. Various protein complexes in the cell are designed to handle, transform and use such forces. For instance, proteins of muscle and the extracellular matrix can withstand considerable stretching forces, hearing-related and mechanosensory proteins can transform weak mechanical stimuli into electrical signals, and regulatory proteins are suited to forcing DNA into loops to control gene expression. Here we review the structure-function relationship of four protein complexes with well defined and representative mechanical functions. The first example is titin, a protein that confers passive elasticity on muscle. The second system is the elastic extracellular matrix protein, fibronectin, and its cellular receptor integrin. The third protein system is the transduction apparatus in hearing and other mechanical senses, likely containing cadherin and ankyrin repeats. The last system is the lac repressor protein, which regulates gene expression by looping DNA. This review focuses on atomic level descriptions of the physical mechanisms underlying the various mechanical functions of the stated proteins.

Heelys injuries in children

INTRODUCTION

Heelys, a type of shoes with stealth wheels, are extremely popular among children in Singapore. The widespread availability of cheap imitations has led to a proliferation of young users. Coupled with a total lack of safety equipment and instructions, these shoes can lead to significant injuries. The purpose of this study was to examine the incidence and type of injuries sustained by children using Heelys.

METHODS

During a seven-month period from February to August 2004, all children treated at the Paediatric Orthopaedic Department of the KK Women's and Children's Hospital, were asked if the injury was sustained while "heeling". All the patients were reviewed by the authors. A total of 37 patients with significant injuries sustained while "heeling" were identified. Their radiographs and clinical charts were reviewed. The patients and/or their parents were also interviewed to obtain additional information.

RESULTS

Upper limb injuries were by far the most common. Distal radius fractures and elbow injuries predominated. None of the children used safety gear.

CONCLUSION

"Heeling" can lead to serious injuries despite the relatively low velocity involved. Children and their parents need to be educated on the use of safety gear.

Positive regulation of hepatic carnitine palmitoyl transferase 1A (CPT1A) activities by soy isoflavones and L-carnitine

BACKGROUND

Genistein increases CPT1A, a rate-limiting enzyme in the beta-oxidation pathway, enzyme activity by increasing CPT1A transcription in HepG2 cells and, consequently, suppresses high fat induced obesity in C57BL/6J mice. Genistein and daidzein are the most abundant isoflavones in soy.

AIM OF STUDY

To investigate the effect of co-treatment of genistein and L-carnitine on CPT1A enzyme activity and to determine whether daidzein also increases CPT1A activity and to establish a cell line that can be used to screen chemicals to regulate CPT1A transcription.

METHODS

The enzyme activities of CPT1A were determined after HepG2 cells were incubated with 10 microM genistein or 10 microM daidzein or 1 mM L-carnitine or in combination with 10 microM genistein and 1 mM L-carnitine or in combination with 10 microM daidzein and 1 mM L-carnitine. The mRNA expression levels of CPT1A were determined by real time PCR method after HepG2 cells were incubated with 10 microM genistein or 10 microM daidzein. A suggested CPT1A promoter region was cloned from human genomic DNA and the CPT1A promoter-luciferase reporter gene construct was made, and the promoter-reporter gene construct was transfected into human hepatoma cell line Huh7.

RESULTS

The enzyme activity of CPT1A was at least 2.3- fold higher in L-carnitine and genistein co-treated HepG2 cells than either single-agent treated cells. Daidzein also significantly increased the mRNA expression of CPT1A as well as the enzyme activity of CPT1A. A stable Huh7 cell line, which was selected after Huh7 cells were transfected with CPT1A promoter luciferase reporter gene construct, was characterized by confirming that luciferase activity of the cell line can be regulated by genistein and daidzein as well as clofibrate, a well-known CPT1A mRNA up-regulating drug.

CONCLUSIONS

Genistein and daidzein can up-regulate CPT1A enzyme activity through up-regulation of CPT1A transcription. Co-treatment of L-carnitine and genistein additively increases CPT1A enzyme activity in HepG2 cells. A stable Huh7 cell line transfected with the CPT1A promoter luciferase reporter gene was established and characterized.

Does soil CO2 efflux acclimatize to elevated temperature and CO2 during long-term treatment of Douglas-fir seedlings?

We investigated the effects of elevated soil temperature and atmospheric CO2 on soil CO2 efflux (SCE) during the third and fourth years of study. We hypothesized that elevated temperature would stimulate SCE, and elevated CO2 would also stimulate SCE with the stimulation being greater at higher temperatures. The study was conducted in sun-lit controlled-environment chambers using Douglas-fir (Pseudotsuga menziesii) seedlings grown in reconstructed litter-soil systems. We used a randomized design with two soil temperature and two atmospheric CO2 treatments. The SCE was measured every 4 wk for 18 months. Neither elevated temperature nor CO2 stimulated SCE. Elevated CO2 increased the temperature sensitivity of SCE. During the winter, the relationship between SCE and soil moisture was negative but it was positive during the summer. The seasonal patterns in SCE were associated with seasonal changes in photosynthesis and above-ground plant growth. SCE acclimatized in the high-temperature treatment, probably because of a loss of labile soil carbon. Elevated CO2 treatment increased the temperature sensitivity of SCE, probably through an increase in substrate availability.

Effect of butyric acid on the performance and carcass yield of broiler chickens

Short-chain fatty acids such as butyrate are considered potential alternatives to antibiotic growth promoters. The efficacy of butyric acid on performance and carcass characteristics of broiler chickens was tested in two studies. The effect of dietary butyrate on the ability to withstand coccidial oocyte challenge also was investigated. In experiment 1, male broiler chickens were fed diets supplemented with 0 or 11 ppm virginiamycin or 0.2 or 0.4% butyric acid (as mono-, di-, and triglyceride). In experiment 2, broilers were fed bacitracin methylene disalicylate or 0.1 or 0.2% butyric acid. In another trial, birds vaccinated against coccidiosis were challenged with oocytes at 21 d and examined 6 d later. In experiment 1, diet treatments had no effect on body weight gain. Feed intake of the birds fed 0.4% butyric acid was decreased (P < 0.01) compared with birds fed the nonmedicated diet during the starter period, whereas birds fed 0.2% butyric acid had similar feed intake to the control birds. In experiment 2, diet treatments did not affect the performance of broiler chicks while carcass weight and breast meat yield increased (P < 0.01) in birds fed 0.2% butyric acid. With oocyte challenge, birds that had received butyric acid before challenge showed higher growth rate following the challenge compared with birds that received nonmedicated feed. Bacitracin decreased (P < 0.05%) duodenal villi crypt depth, whereas villus length was similar in birds fed butyric acid or the nonmedicated control diet. These results show that 0.2% butyric acid can help to maintain the performance and carcass quality of broilers, especially in vaccinated birds challenged with coccidiosis.

One hundred years of orthopaedic education in Singapore

The Department of Orthopaedic Surgery at the University of Malaya (in Singapore) was established in 1952. Prior to this, the teaching of Orthopaedic Surgery at the University was undertaken by the Department of Surgery under the Professor of Surgery and Professor of Clinical Surgery. From a course consisting of 15 weekly classes on fractures for 18 undergraduates in the late 1930s, and the clinical postings in orthopaedic surgery for over 40 students in 1952, the programme now encompasses an exposure to musculoskeletal diseases and trauma in all 5 years of the undergraduate course. Over this time, the spectrum of clinical conditions has also changed, and with it the emphasis on the conditions to be taught; from that dealing primarily with tuberculosis of bones and joints, poliomyelitis, and childhood deformity, to those resulting from degenerative disorders, sports injuries, industrial and motor vehicle accidents, and cancer. The students are now taught orthopaedic surgery in all the major public hospitals. Local postgraduate training programmes for orthopaedic surgery started in the 1980s. From 1993, a more structured training and assessment programme was introduced for basic and advanced training in surgery and orthopaedics. Advanced trainees rotate through the various teaching hospitals to expose them to a wider range of orthopaedic problems as well as teachers. The postgraduate training programme is now well established, and Singapore is accredited by the Royal College of Surgeons of Edinburgh as an orthopaedic training centre for higher surgical training.

Nosocomial transmission of Mycobacterium tuberculosis in a children's hospital

An infant was admitted for evaluation of respiratory distress and tracheomalacia. After several weeks of hospitalization, both the infant and her mother were diagnosed with culture-positive pulmonary tuberculosis (TB). Sixteen pediatric patients and 293 health care workers were evaluated for exposure to Mycobacterium tuberculosis. Tuberculin skin test conversions occurred in 6.7% of patients and 1.9% of pediatric health care workers. While nosocomial transmission of TB is relatively rare in children's hospitals, this report highlights the differences between TB control efforts in pediatric vs. adult facilities, including the importance of screening the adult visitors of children admitted with suspected TB.

Mesenchymal stem cells in musculoskeletal tissue engineering: a review of recent advances in National University of Singapore

A key factor in the tissue engineering approach to tissue repair and regeneration is the use of appropriate cells. Mesenchymal stem cells (MSCs) are derived from bone marrow stroma or connective tissues and they have the potential to differentiate into various mesenchymal cell lines in vitro and in vivo. These cells hold great promise for musculoskeletal tissue engineering. This review is based mainly on the work which has been done in the National University of Singapore on the use of MSCs for engineering cartilage, growth plate, bone and tendon/ligament as well as the clinical trail of autologous chondrocyte implantation. It can help to shape future research on musculoskeletal tissue engineering.

Decreased access to health care and social isolation among young adults with cerebral palsy after leaving school

OBJECTIVE

To examine if leaving special schools has a negative impact on the health care and social isolation of young adults with cerebral palsy.

METHODS

Young adults with cerebral palsy, aged between 15 and 22 years, were divided into 2 cohorts: current students, who were still receiving services from special schools, and school-leavers, who had since been discharged from care. A questionnaire and physical examination were administered to assess the extent of disability, health care received by, and social isolation of these young adults.

RESULTS

School-leavers had a greater degree of dissability than did students, although the results were not statistically significant. Health care exposure to specialists, general practitioners, therapists physiotherapists, occupational therapists, and/or speech therapists), and medical social workers decreased after leaving school; with the exception of contact with general practitioners, these results were significant (p<0.05). The entire cohort was more socially isolated than a control cohort. School-leavers participated in fewer activities outside their homes, but showed less concern about their disability than did current students.

CONCLUSIONS

Young adults with cerebral palsy continue to have health care and lifestyle needs after leaving school, which are currently not being adequately met.

Change of complement system predicts the outcome of patients with severe thermal injury

To establish the clinical relevance of the changes in the complement system in patients with thermal injury, we studied 20 patients who had third-degree burns on more than 60% of total body surface area. Their levels of the C3, C4, soluble C5b-9, and functional hemolytic activities of total (CH50) and alternative (AH50) complement pathways were sequentially measured for 2 weeks after thermal injury. All patients showed low C3 levels initially but increased C3 levels in the following days. The increasing trend of C3 levels was prominent in survivors but transient and diminished in nonsurvivors. The change of levels of C3, CH50, and AH50 was closely associated with one another, and their chronological trends related to the survival of patients (P =.0060,.0064 and.0066, respectively). The recovery of C3, AH50, and CH50 to normal or supranormal level during the early treatment period relates to the survival of patients with thermal injury. The failure of recovery of the complement system indicates a poor prognosis for patients and the monitoring of complement system might be beneficial in the care of patients with thermal injury.

Construction of high-density bacterial colony arrays and patterns by the ink-jet method

We have developed a method for fabricating bacterial colony arrays and complex patterns using commercially available ink-jet printers. Bacterial colony arrays with a density of 100 colonies/cm(2) were obtained by directly ejecting Escherichia coli (E. coli) onto agar-coated substrates at a rapid arraying speed of 880 spots per second. Adjusting the concentration of bacterial suspensions allowed single colonies of viable bacteria to be obtained. In addition, complex patterns of viable bacteria as well as bacteria density gradients were constructed using desktop printers controlled by a simple software program.