The manuscript, ‘Bone strength in children: understanding basic bone biomechanics’ [1] published in 2015 summarises key paediatric orthopaedic biomechanical concepts well, however, there appears to be an error in Figure 4. The authors state that osteopetrosis leads to more bone mineralisation and therefore an increased extrinsic stiffness, while both ductility and toughness are both reduced. In rickets, they correctly argue that decreased mineralisation leads to increased ductility and consequently higher ultimate displacement at the expense of reduced extrinsic stiffness which therefore decreased the ultimate load needed to fracture bone. These statements are in contradiction to Figure 4, a load-displacement curve comparing osteopetrosis and rickets to normal bone. This figure suggests that it is osteopetrosis which has a decreased ultimate load required to fracture, but greater ductility, compared to normal bone. It also suggests rickets which would have a greater ultimate load before fracture, decreased ductility and increased stiffness compared to normal bone. Figure 4 not only contradicts previous information stated in the paper, for example, extrinsic stiffness is the gradient of the linear region of the force-displacement curve, it also directly contradicts previous literature. Cole et al[2] graphically demonstrates stiffness, ultimate load, ductility and failure on a load-displacement curve for bone. I would suggest that the paper be edited and...
The manuscript, ‘Bone strength in children: understanding basic bone biomechanics’ [1] published in 2015 summarises key paediatric orthopaedic biomechanical concepts well, however, there appears to be an error in Figure 4. The authors state that osteopetrosis leads to more bone mineralisation and therefore an increased extrinsic stiffness, while both ductility and toughness are both reduced. In rickets, they correctly argue that decreased mineralisation leads to increased ductility and consequently higher ultimate displacement at the expense of reduced extrinsic stiffness which therefore decreased the ultimate load needed to fracture bone. These statements are in contradiction to Figure 4, a load-displacement curve comparing osteopetrosis and rickets to normal bone. This figure suggests that it is osteopetrosis which has a decreased ultimate load required to fracture, but greater ductility, compared to normal bone. It also suggests rickets which would have a greater ultimate load before fracture, decreased ductility and increased stiffness compared to normal bone. Figure 4 not only contradicts previous information stated in the paper, for example, extrinsic stiffness is the gradient of the linear region of the force-displacement curve, it also directly contradicts previous literature. Cole et al[2] graphically demonstrates stiffness, ultimate load, ductility and failure on a load-displacement curve for bone. I would suggest that the paper be edited and Figure 4 updated to correctly represent the biomechanical properties of osteopetrosis and rickets to avoid confusion among readers. This can simply be achieved by swapping the labels for osteopetrosis and rickets.
Regards
Mahmoud El-khatib
1. Forestier-Zhang L, Bishop N. Bone strength in children: understanding basic bone biomechanics. Archives of disease in childhood - Education & practice edition. 2015;101(1):2-7.
2. Cole J, van der Meulen M. Whole Bone Mechanics and Bone Quality. Clinical Orthopaedics and Related Research®. 2011;469(8):2139-2149.
We highly appreciate the valuable comments by Lyall and colleagues concerning the importance of congenital HIV as a differential diagnosis in any clinical setting where immunodeficiency is considered. Our paper is focusing on the concept of normality in terms of numbers and severity of infections, and clinical clues to primary immunodeficiency syndromes. Although secondary immunodeficiencies were not within the scope of our paper, we agree that it would have been a great opportunity to raise the awareness regarding the clinical presentation of HIV infection in children.
Yours sincerely,
Per Wekell, Olof Hertting, Daniel Holmgren, Anders Fasth
We read with interest the article by Leong et al. on the use of polysomnography (PSG) in children (Leong et al. 2019), covering indications for PSG, along with limitations of oximetry, and clearly outlining how to undertake and interpret polysomnography in paediatric patients. It briefly discusses limited channel recordings (respiratory polygraphy, RP) and concludes that this ‘is not standard practice’.
In many paediatric centres RP is standard practice, and routinely used for assessment of sleep-disordered breathing (SDB) in children, with the most common diagnosis being obstructive sleep apnoea (OSA).
In a recent survey of 20 United Kingdom and Republic of Ireland paediatric sleep centres (Russo, 2017), all centres reported use of RP for diagnosis of SDB, with 14 centres using this as the main diagnostic method. PSG was performed in 10 centres, contributing a small part of workload (median of total workload: 5% (range: 1%-15%)). The majority of all studies were performed within a hospital setting, with home oximetry/RP use reported in 25% of centres. Indeed, the UK has led the way in home RP (Kingshott 2019). As international leaders in the field acknowledge, ‘the times they are a changing.’ (Gozal 2015)
RP utilises measures of airflow, respiratory effort by inductance plethysmography bands, oxygen saturation, carbon dioxide and heart rate monitoring. This allows accurate detection and discrimination of obstructive, central and mixed apnoeas/hypop...
We read with interest the article by Leong et al. on the use of polysomnography (PSG) in children (Leong et al. 2019), covering indications for PSG, along with limitations of oximetry, and clearly outlining how to undertake and interpret polysomnography in paediatric patients. It briefly discusses limited channel recordings (respiratory polygraphy, RP) and concludes that this ‘is not standard practice’.
In many paediatric centres RP is standard practice, and routinely used for assessment of sleep-disordered breathing (SDB) in children, with the most common diagnosis being obstructive sleep apnoea (OSA).
In a recent survey of 20 United Kingdom and Republic of Ireland paediatric sleep centres (Russo, 2017), all centres reported use of RP for diagnosis of SDB, with 14 centres using this as the main diagnostic method. PSG was performed in 10 centres, contributing a small part of workload (median of total workload: 5% (range: 1%-15%)). The majority of all studies were performed within a hospital setting, with home oximetry/RP use reported in 25% of centres. Indeed, the UK has led the way in home RP (Kingshott 2019). As international leaders in the field acknowledge, ‘the times they are a changing.’ (Gozal 2015)
RP utilises measures of airflow, respiratory effort by inductance plethysmography bands, oxygen saturation, carbon dioxide and heart rate monitoring. This allows accurate detection and discrimination of obstructive, central and mixed apnoeas/hypopnoeas.
Whilst PSG can add useful additional information for complex or subtle SDB presentations, most patients with possible SDB can be adequately assessed using RP, particularly in straightforward OSA.
RP’s set-up and reporting times are shorter than PSG, allowing best use of limited resources, as well as increased ability to perform studies at home.
The utility of RP compared with PSG is very favourable (Tan 2014), although potential for underscoring events (inability to detect EEG arousal on RP) is acknowledged. RP is often better tolerated than PSG in children with complex medical difficulties. In UK centres which have ability to perform PSG, this is usually still not the first choice diagnostic test for SDB assessment.
We agree PSG is the current gold standard for assessment of SDB in children, however RP is the optimal sleep study type for diagnosing most cases of SDB in a high-throughput setting such as the UK.
This approach is recognised in European paediatric consensus guidelines (Kaditis 2016) and follows a paradigm shift away from polysomnography in adult diagnostic services.
REFS:
Leong KW, Griffiths A, Adams A, et al How to interpret polysomnography
Archives of Disease in Childhood - Education and Practice Published Online First: 15 October 2019. doi: 10.1136/archdischild-2018-316031
Russo, K (2017). Paediatric respiratory sleep studies in UK and Ireland: a survey of current practice. Unpublished Masters thesis, City, University of London, London, UK
(data partially published Archives of Disease in Childhood 2019;104(Suppl 2): A202: G502(P)
Kingshott RN, Gahleitner F, Elphick HE, et al Cardiorespiratory sleep studies at home: experience in research and clinical cohorts
Archives of Disease in Childhood 2019;104:476-481 doi 10.1136/archdischild-2019-rcpch.485
Gozal D, Kheirandish-Gozal L, Kaditis AG Home sleep testing for the diagnosis of pediatric obstructive sleep apnea: the times they are a changing...!
Curr Opin Pulm Med 2015 Nov;21(6):563-
Tan et al Overnight polysomnography versus respiratory polygraphy in the diagnosis of pediatric obstructive sleep apnea
Sleep 2014 Feb 1;37(2):255-60. doi: 10.5665/sleep.3392.
Kaditis AG, Alonso Alvarez ML, Boudewyns A, et al. Obstructive sleep disordered breathing in 2-18
year-old children: diagnosis and management.
Eur Respir J 2016;47(1):69-94.
We read with interest the extensive review of clinical presentations of immunodeficiency in childhood in the Archives Education & Practice October edition, we enjoyed the way that clinical scenarios were presented, most useful for the front line paediatrician.
However, we were surprised and disappointed that by far the most common single cause of paediatric immunodeficiency and the most important differential diagnosis, congenital HIV infection, was not mentioned at all in the piece.
This seemed a significant oversight as in the UK, annually there are still 20-30 children per year diagnosed with HIV, either born here, or new arrivals to the country (https://www.ucl.ac.uk/nshpc/) . This is an important differential diagnosis for the infant presenting in respiratory failure with SCID, or the child with invasive pneumococcal disease, or recurrent shingles, or recurrent bacterial infections, or lymphopaenia. More importantly, this is now a highly treatable condition, and early treatment is correlated with the best long term outcomes.
We hope that your readers may be reminded of this, and will rule out HIV infection, prior to embarking on costly and complex immune investigations.
I congratulate Uzuna, Bailie and Murray on an excellent summary of common oncological abdominal masses and an approach for the general paediatrician. Ensuring that children with abdominal masses are correctly identified, investigated and referred by their local paediatrician is crucial, particularly as there is evidence of later diagnosis in the UK compared to other European countries (Pritchard-Jones et al., 2016)
They note that urinary catecholamines can be a useful rule-in test for suspected neuroblastoma (90% sensitivity). The Childrens Cancer and Leukaemia Group in the UK recommends that all children with a suspected renal tumour should also have urinary catecholamines assessed to reduce the risk of incorrectly treating a neuroblastoma as it may be difficult to determine if a mass is renal or adrenal by imaging alone. Biopsy of renal tumours in young children without features atypical of Wilms tumour is no longer recommended as it rarely changes clinical management, but this approach will only be successful if the child is fully assess for "atypical features", such as raised urinary catecholamines. In my experience there can be a significant wait for urinary catecholamine results and so having a sample sent by the local team is valuable.
I would also like to highlight a small error in the legend that they have included for the Figure I provided (Figure 1). The National Cancer Registration and Analysis Service does not routinely include all...
I congratulate Uzuna, Bailie and Murray on an excellent summary of common oncological abdominal masses and an approach for the general paediatrician. Ensuring that children with abdominal masses are correctly identified, investigated and referred by their local paediatrician is crucial, particularly as there is evidence of later diagnosis in the UK compared to other European countries (Pritchard-Jones et al., 2016)
They note that urinary catecholamines can be a useful rule-in test for suspected neuroblastoma (90% sensitivity). The Childrens Cancer and Leukaemia Group in the UK recommends that all children with a suspected renal tumour should also have urinary catecholamines assessed to reduce the risk of incorrectly treating a neuroblastoma as it may be difficult to determine if a mass is renal or adrenal by imaging alone. Biopsy of renal tumours in young children without features atypical of Wilms tumour is no longer recommended as it rarely changes clinical management, but this approach will only be successful if the child is fully assess for "atypical features", such as raised urinary catecholamines. In my experience there can be a significant wait for urinary catecholamine results and so having a sample sent by the local team is valuable.
I would also like to highlight a small error in the legend that they have included for the Figure I provided (Figure 1). The National Cancer Registration and Analysis Service does not routinely include all benign tumours (such as congenital mesoblastic nephroma) in the database, so the "other cancers" group does not include CMN as stated in the figure legend. Instead, these are neuroendocrine tumours (e.g. PNET), non Hodgkin lymphomas and sarcomas where the initial mass assessed was felt to be renal in origin.
Based on data from the UK Wilms tumour trials and the SIOP Renal Tumour Study Group trials, mesoblastic nephroma is the most common renal tumour in children under 3 months, but is very rare after 6 months of age. Interested readers wanting to know more about the epidemiology and clinical features of mesoblastic nephroma should read England et al., 2011 or Gooskens et al, 2017.
Dear Editor
The manuscript, ‘Bone strength in children: understanding basic bone biomechanics’ [1] published in 2015 summarises key paediatric orthopaedic biomechanical concepts well, however, there appears to be an error in Figure 4. The authors state that osteopetrosis leads to more bone mineralisation and therefore an increased extrinsic stiffness, while both ductility and toughness are both reduced. In rickets, they correctly argue that decreased mineralisation leads to increased ductility and consequently higher ultimate displacement at the expense of reduced extrinsic stiffness which therefore decreased the ultimate load needed to fracture bone. These statements are in contradiction to Figure 4, a load-displacement curve comparing osteopetrosis and rickets to normal bone. This figure suggests that it is osteopetrosis which has a decreased ultimate load required to fracture, but greater ductility, compared to normal bone. It also suggests rickets which would have a greater ultimate load before fracture, decreased ductility and increased stiffness compared to normal bone. Figure 4 not only contradicts previous information stated in the paper, for example, extrinsic stiffness is the gradient of the linear region of the force-displacement curve, it also directly contradicts previous literature. Cole et al[2] graphically demonstrates stiffness, ultimate load, ductility and failure on a load-displacement curve for bone. I would suggest that the paper be edited and...
Show MoreDear Editor,
We highly appreciate the valuable comments by Lyall and colleagues concerning the importance of congenital HIV as a differential diagnosis in any clinical setting where immunodeficiency is considered. Our paper is focusing on the concept of normality in terms of numbers and severity of infections, and clinical clues to primary immunodeficiency syndromes. Although secondary immunodeficiencies were not within the scope of our paper, we agree that it would have been a great opportunity to raise the awareness regarding the clinical presentation of HIV infection in children.
Yours sincerely,
Per Wekell, Olof Hertting, Daniel Holmgren, Anders Fasth
We read with interest the article by Leong et al. on the use of polysomnography (PSG) in children (Leong et al. 2019), covering indications for PSG, along with limitations of oximetry, and clearly outlining how to undertake and interpret polysomnography in paediatric patients. It briefly discusses limited channel recordings (respiratory polygraphy, RP) and concludes that this ‘is not standard practice’.
In many paediatric centres RP is standard practice, and routinely used for assessment of sleep-disordered breathing (SDB) in children, with the most common diagnosis being obstructive sleep apnoea (OSA).
In a recent survey of 20 United Kingdom and Republic of Ireland paediatric sleep centres (Russo, 2017), all centres reported use of RP for diagnosis of SDB, with 14 centres using this as the main diagnostic method. PSG was performed in 10 centres, contributing a small part of workload (median of total workload: 5% (range: 1%-15%)). The majority of all studies were performed within a hospital setting, with home oximetry/RP use reported in 25% of centres. Indeed, the UK has led the way in home RP (Kingshott 2019). As international leaders in the field acknowledge, ‘the times they are a changing.’ (Gozal 2015)
RP utilises measures of airflow, respiratory effort by inductance plethysmography bands, oxygen saturation, carbon dioxide and heart rate monitoring. This allows accurate detection and discrimination of obstructive, central and mixed apnoeas/hypop...
Show MoreDear Editor,
We read with interest the extensive review of clinical presentations of immunodeficiency in childhood in the Archives Education & Practice October edition, we enjoyed the way that clinical scenarios were presented, most useful for the front line paediatrician.
However, we were surprised and disappointed that by far the most common single cause of paediatric immunodeficiency and the most important differential diagnosis, congenital HIV infection, was not mentioned at all in the piece.
This seemed a significant oversight as in the UK, annually there are still 20-30 children per year diagnosed with HIV, either born here, or new arrivals to the country (https://www.ucl.ac.uk/nshpc/) . This is an important differential diagnosis for the infant presenting in respiratory failure with SCID, or the child with invasive pneumococcal disease, or recurrent shingles, or recurrent bacterial infections, or lymphopaenia. More importantly, this is now a highly treatable condition, and early treatment is correlated with the best long term outcomes.
We hope that your readers may be reminded of this, and will rule out HIV infection, prior to embarking on costly and complex immune investigations.
I congratulate Uzuna, Bailie and Murray on an excellent summary of common oncological abdominal masses and an approach for the general paediatrician. Ensuring that children with abdominal masses are correctly identified, investigated and referred by their local paediatrician is crucial, particularly as there is evidence of later diagnosis in the UK compared to other European countries (Pritchard-Jones et al., 2016)
They note that urinary catecholamines can be a useful rule-in test for suspected neuroblastoma (90% sensitivity). The Childrens Cancer and Leukaemia Group in the UK recommends that all children with a suspected renal tumour should also have urinary catecholamines assessed to reduce the risk of incorrectly treating a neuroblastoma as it may be difficult to determine if a mass is renal or adrenal by imaging alone. Biopsy of renal tumours in young children without features atypical of Wilms tumour is no longer recommended as it rarely changes clinical management, but this approach will only be successful if the child is fully assess for "atypical features", such as raised urinary catecholamines. In my experience there can be a significant wait for urinary catecholamine results and so having a sample sent by the local team is valuable.
I would also like to highlight a small error in the legend that they have included for the Figure I provided (Figure 1). The National Cancer Registration and Analysis Service does not routinely include all...
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