Avascular necrosis of the hipBMJ 2019; 365 doi: https://doi.org/10.1136/bmj.l2178 (Published 30 May 2019) Cite this as: BMJ 2019;365:l2178
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I am grateful to the authors for such clear exposition and mentioning Sickle cell anaemia. Equally valuable is the contribution of Dr Felix Konotey-Ahulu . He reminds us that Sickle cell -haemoglobin C disease is different , but even more important in terms of pathogenicity of ANFH.
The amount of melanin in the skin and the place of origin of the forefathers of the patient are rather less relevant today.
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AVASCULAR HIP NECROSIS: SICKLE HAEMOGLOBINOPATHY PREDOMINATES WORLDWIDE.
Jonathan Lamb and colleagues have done well to draw attention to this “easily missed” condition  but, globally, sickle haemoglobinopathy far outstrips anything else in the aetiology of the problem [2,3,4]. Admittedly they mention “sickle cell anaemia” among what they call “risk factors” but Sickle Cell Anaemia is “SS” (sickle haemoglobin S gene from both parents) which phenotype is known to be less associated with aseptic necrosis than sickle cell haemoglobin C disease phenotype, “SC” (S gene from one parent and C gene from the other) for the clear reasons of blood viscosity [2-5].
Sickle Cell Anaemia, Sickle Cell Haemoglobin C Disease, Sickle Cell beta-Thalassaemia Phenotypic Differences in Avascular Necrosis
Of 583 consecutive “SS” patients 12 had one or other hip involved, and 1 had both hips involved while of 563 consecutive “SC” patients 13 had just the left hip involved, 18 the right hip aseptically necrosed, and 9 had both hips involved [2, 5]. To mention sickle cell anaemia therefore, and omit sickle cell haemoglobin C disease is only partial truth. Many UK General Practitioners are so well aware of this that they request Haemoglobin electrophoresis on anybody walking into their surgery with a limp be they black or white – because the sickle cell gene frequency in some white people in Greece and in Eti-Turks is greater than that in my own country Ghana.
Jonathan Lamb et al list fewer conditions that cause aseptic necrosis of the femoral head than the 25 that J E Nixon  listed in 1983 in the Journal of the Royal Society of Medicine, but their article  has admirably succeeded in alerting clinicians about this condition which afflicts not just Caucasians but the entire world. We note that Sickle Cell Anaemia “SS” is not the same as Sickle Cell Haemoglobin C disease “SC”. Sickle Cell Trait is “AS” phenotype.
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F I D Konotey-Ahulu MB BS MD(Lond) FRCP(Lond) FRCP(Glasg) DTMH(L’pool) DSc (Hon UCC) DSc (Hon UH) FGA FGCP FWACP FTWAS, ORDER OF MERIT (OFFICER). Kwegyir Aggrey Distinguished Professor of Human Genetics, Faculty of Science, University of Cape Coast, Ghana, and Former Director Ghana Institute of Clinical Genetics Ghana and Consultant Physician Genetic Counsellor in Sickle Cell and Other Haemoglobinopathies Korle Bu Teaching Hospital Accra, and at Phoenix Hospital Group, 9 Harley Street, London W1G 9AL.
1 Lamb JN, Holton C, O’Connor P, Giannoudis PV. Avascular necrosis of the hip. BMJ 1 June 2019, Vol 365, p 325 (BMJ 2019; 365:I2178)
2 Konotey-Ahulu FID. The Sickle Cell Disease Patient: Natural History from a Clinico-epidemiological study of the first 1550 patients of Korle Bu Hospital Sickle Cell Clinic. The Macmillan Press Ltd, London 1991 & 1992 and T-AD Co Watford 1996.
3 Konotey-Ahulu FID. Hip disease in Africans, Lancet 1970; 1: 99.
4 Konotey-Ahulu FID. Hip pain and radiographic signs of osteoarthritis: Sickle Cell and other haemoglobinopathy differential diagnosis. BMJ Rapid response to Nieuwenhhuisje MJ, Nelissen RG. Hip pain and radiographic signs of osteoarthritis. BMJ 2015; 351:6262 (03 December 2015) BMJ 2015;351:h5983
5 Konotey-Ahulu FID. Pattern of Sickle Cell Disease in Accra. A Study of 1550 consecutive patients. Dissertation presented to University of London for the Postgraduate Diploma of Doctor of Medicine 1971.
6 Humble JG. et al. A family illustrating the double inheritance of a sickle cell trait and of Mediterranean anaemia. J Clin Path 1954; 7: 201-208.
7 Ringelhann B, Konotey-Ahulu FID. Haemoglobinopathies and Thalassaemia in Mediterranean areas and in West Africa: historical and other perspectives 1910-1997 – A Century Review. Atti del’Accademia dela Science di Ferrara 1998: 74: 267-307.
8. Nixon JE. Avascular necrosis of bone: a review. J R Soc Med. 1983; 76: 681-692.
Competing interests: No competing interests