The child with unexplained fractures

By Dr Colin R Paterson, Department of Medicine, University of Dundee

 

Unexplained fractures may be the hallmark of all forms of brittle bone disease, explains Dr Colin Paterson

 

 

 

 

 

 


Dr Colin R Paterson is a former staff member of the Department of Medicine at the University of Dundee, Scotland.

This article was previously published in the New Law Journal Expert witness supplement, NLJ Vol 147 (1997) pages 648, 650 and 652

The article is published here with the kind permission of the Editor of the New Law Journal.

 

 

 

 

 

A recently reported judgment¹ has drawn attention to the frequent difficulty attending the diagnosis of the child with unexplained fractures. To many observers the failure of parents to come up with an explanation for frac­tures found radiologically is ipso facto ev­idence for non-accidental injury; the lack of explanation must represent a failure to tell the truth about their own or their partners' actions. However, unexplained fractures in childhood are also the hall­mark of all forms of brittle bone disease and immense harm can be done to fami­lies by the inaccurate diagnosis of non-ac­cidental injury.

 

Much of our research over the last 25 years has related to the clinical aspects of the brittle bone diseases and we hold a database with details of over 1,300 pa­tients. The best known of these is osteogenesis imperfecta which has a prevalence of about one in 10,000 in the United King­dom. It is caused by abnormalities in col­lagen, the fibrous protein essential for the mechanical strength of bone. In turn, in most cases, this is now known to be caused by defects in the genes responsible for collagen formation. Since collagen is abnormal in tissues other than bone, patients with osteogenesis imperfecta now have detectable features in addition fractures. These include blue or grey coloration of the sclerae (whites of the eyes), discoloration and fragility of teeth, laxity of joints and an increased tendency to bruising or pinpoint bruises known as petechiae. The bruising thought to reflect abnormalities in the collagen of small blood vessels. X-rays may show obvious abnormalities but in a majority of patients the appearances are normal at the time of the first few fractures; many of the abnormalities seen later reflect the fractures and the immobilisation used in their treatment. In some cases osteogenesis imperfecta is passed down from a parent to a child, but many cases are "sporadic" with no known family history.

 

In most patients with osteogenesis im­perfecta the diagnosis is made without undue difficulty on the basis of the clini­cal signs, the fracture history or the fam­ily history. In a retrospective survey of 802 known cases of osteogenesis imperfecta in the United Kingdom² we found that in 691 the diagnosis had been made confi­dently at birth or at the time of the first fracture. In 96 cases the parents were ac­cused of non-accidental injury on at least one occasion. In 15 cases they had had to contend with case conferences, care pro­ceedings or criminal proceedings.

 

Over the last 12 years we have identi­fied a distinctive pattern in a minority of patients initially thought to have osteo­genesis imperfecta. In this variant, known as temporary brittle bone disease³, the fractures are limited to the first year of life and, to a large extent, the first six months of life. The fracture pattern is often dis­tinctive with rib fractures and fractures at the ends of long bones (metaphyseal fractures) being frequent. These patients may have other features such as vomiting [often projectile) and anaemia. While there s usually no family history of fractures, there is a family history of joint laxity in about two thirds of cases. The cause of the disorder is not yet known but it appears o be more common in twins and infants born before full term.

 

It is not surprising that both osteogenesis imperfecta and temporary brittle bone disease are often considered in cases in which a child is found to have unex­plained fractures. This article summarises a personal experience of cases in which the author prepared a report on the causes of fractures and the likelihood of an un­derlying bone disease. Since these cases have been studied over some 21 years it has been possible to follow up most of the children concerned for substantial peri­ods.

 

Methods

A database was prepared to include de­tails of each child with information on the mode of referral, the diagnosis reached personally, the legal outcome and the de­tails of follow-up. Additional clinical in­formation was recorded in each case. The current report is restricted to 128 patients living in the United Kingdom, in whom the major problem was the fractures.

 

Results

Table I shows the source of the referrals. Table II shows the diagnosis made by the author in each case. While patients with temporary brittle bone disease were not recognised as such before 1985, it was clear in retrospect that some patients seen earlier had this disorder. Two infants with an initial diagnosis of temporary brittle bone disease were later re-classified as osteogenesis imperfecta in the light of sub­sequent fractures.

 

Of the 105 patients thought to have bone disorders the author provided evi­dence for care proceedings in 102. Of these infants the eventual outcome was that 78 were returned to their parents (56 initially with conditions), three went to other fam­ily members and 21 were removed per­manently from their families. In three of these the parents had given up before for­mal proceedings. In seven families the parents separated; in three because one parent was blamed.

 

Of the 33 children thought to have osteogenesis imperfecta 25 were returned to their parents. One died later with bronchopneumonia and multiple unexplained gastrointestinal problems. The remaining patients have been followed up for be­tween one and 18 years (total 136 patient-years, mean 5.6 years). There was no evidence of non-accidental injury in this period.

 

Of the 65 children thought to have tem­porary brittle bone disease, 48 were re­turned to their parents. Two died later; one with a cot death and one with late sequelae of birth injury; in neither was non-accidental injury postulated. In 43 of the remaining patients follow-up information was available for between 1 and 11 years (total 248 patient years, mean 5.8 years). There was no evidence of non-accidental injury during this period.

 

 

 

Table I

Source of medico-legal referrals 1974-96

 

Parents' representatives                             102

Guardians ad litem                                         8

Local authority                                              6

Senior hospital staff                                       8

General practitioners                                      3

Police                                                            1

Total                                                         128


 

 

 

 

 

Table 2

Diagnosis in 128 patients referred for the diagnosis of unexplained fractures

 

Osteogenesis imperfecta                            33

Temporary brittle bone disease                  65

Vitamin D deficiency rickets                         5

Scurvy (vitamin C deficiency)                       1

Hypophosphatasia*                                     1

Accidental injury                                          9

Unresolved/non-accidental injury                 14

Total                                                         128

 

* Hypophosphatasia is an uncommon heritable disorder of bone


 

 

 

 

In the whole group of 105 children thought to have bone disease the evidence was rejected judicially in 29 cases and for­mally accepted in 23. In the remaining cases there was no formal finding for a va­riety of reasons, most commonly because rehabilitation of the child with the family was agreed without a hearing. Among the 65 patients thought to have temporary brittle bone disease this evidence was re­jected in 18 and accepted in 11; in the re­maining 36 patients there was no judicial finding. An analysis of the clinical findings in these three groups did not demon­strate any differences in relation to a wide range of clinical features.

 

Discussion

Over the last 20 years there has been some reduction in the number of new cases re­ferred in which the diagnosis was osteo­genesis imperfecta. Increased familiarity with the clinical features of this disorder has led to more frequent early diagnosis. In the past some of the cases referred to the courts had classical features such as abnormal sclerae or teeth, or had a clearly positive family history which had not been sought.2

However, retrospective study of con­firmed cases of osteogenesis imperfecta continues to demonstrate that in a mi­nority of patients the diagnosis was ex­tremely difficult at the time of the earlier fractures. Since there may be long frac­ture-free periods in known cases it is pos­sible to be misled by the lack of subsequent fractures. In one particularly unfortunate family, in which the author was not involved legally, a child was taken into care at the age of 18 months after two fractures.

 

A subsequent fracture did not occur for a further 18 months and the diagnosis of osteogenesis imperfecta was only made at the age of five years when she was re­turned to her mother. Retrospective study of the medical records and x-rays in this case revealed little evidence that would have helped to make the correct diagno­sis at the time.

 

While such difficult cases are uncom­mon they occur too frequently in the United Kingdom as a whole to allow for complacency. Our experience in the cur­rent series indicates that where a diagno­sis of osteogenesis imperfecta is made and the child is returned to the parents no ev­idence of subsequent non-accidental in­jury has been observed in 136 patient-years of follow up. In most cases subsequent fractures occurred but mainly at ages at which the child was able to give a clear account of the events.

 

In recent years it has become possible to identify abnormalities in collagen for­mation by cells grown in culture from ex­cised samples of skin. With one approach it was claimed that such abnormalities could be demonstrated in over 80 per cent of cases of osteogenesis, imperfecta4. Such assays are time-consuming and labour-in­tensive; they are not widely available.

 

In the past some reports have relied on such methods even in cases in which there was already ample clinical evidence of os­teogenesis imperfecta. It is important that the limitations of such tests are recognised.

 

Temporary brittle bone disease is a much more controversial subject 5, 6, 7. Some of its features as reported by us are those that have been conventionally regarded as typical of non-accidental injury for the last thirty years8 9. However, the evidence that these features, including rib fractures, and metaphyseal fractures are linked to non-accidental injury, is limited. In addi­tion these fractures occur in a wide range of known bone disorders. For example, rib fractures occur spontaneously in known cases of ordinary osteogenesis imperfecta and may occur in utero. Metaphyseal frac­tures occur not only in osteogenesis im­perfecta but also in at least five other bone disorders in the first year of life.

 

There are four principal types of evi­dence that support the view that tempo­rary brittle bone disease exists and does not represent misdiagnosed non-acciden­tal injury. First the patients all show strik­ing similarities in their clinical features, the types of fractures, the ages at which they occur, the other symptoms such as vomiting, the other signs such as enlarged fontanelles, and the family history obser­vations. Were these infants not thought to have sustained non-accidental injury they would readily have been recognised as having a distinctive syndrome.

 

Second, as with ordinary osteogenesis imperfecta, there is often a striking dis­crepancy between the fractures and other evidence of injury. In typical non-acci­dental injury bruises greatly outnumber fractures. In this disorder there may be over twenty fractures but reliable evidence that no superficial sign of injury was present at the time when the fractures oc­curred.

 

Third, the same syndrome occurs in infants in whom non-accidental injury can be excluded with confidence, gener­ally because the fractures occurred while the child was in hospital.

 

Fourth, the evidence provided in this report emphasises that when these pa­tients were returned to their parents no subsequent evidence of non-accidental in­jury has been identified in 248 patient-years of follow up. The premise underlying care proceedings is that abu­sive parents remain abusive and that there is substantial risk of further non-acciden­tal injury if an abused child is returned. The follow up findings in this report sup­port the view that in this small distinctive group of infants with unexplained frac­tures the diagnosis was not non-acciden­tal injury.

 

Dr Colin R Paterson, Department of Medicine, University of Dundee

 

 

Notes

¹ Wall ] Re AB (child abuse: expert evidence) (1995)1 FLR 181.

² Paterson CR, McAllion SJ (1989) Osteogenesis imperfecta in the differential diagnosis of child abuse. BM] 299:1451.

³ Paterson CR, Burns ], McAllion S] (1993) Osteogenesis imperfecta: the distinction from child abuse and the recognition of a variant form. Amer J Med Genet 45:187.

4 Steiner RD, Pepin M, Byers PH (1996) Studies of collagen synthesis and structure in the differ­entiation of child abuse from osteogenesis imper­fecta. J Pediatr 128: 542.

 5 Smith R, Wynne JM, Hobbs C], Carty H (1995) Osteogenesis imperfecta, non-accidental injury and temporary brittle bone disease Arch Dis Childh 72:269.

6 Shaw DC, Hall CM, Carty H (1995) Osteogen­esis imperfecta: the distinction from child abuse and the recognition of a variant form Amer J Med Genet 56:116.

7 Paterson CR Burns }, McAllion S] (1995) Os­teogenesis imperfecta variant v child abuse: reply Amer J Med Genet 56: 117.

8 Carty HML (1993) Fractures caused by child abuse J Bone Joint Surg 75-B: 849.

9 Chapman S (1993) Recent advances in the radi­ology of child abuse Baill Clin Paediatr 1: 222.

 

Acknowledgements

I am indebted to Mrs E A Monk for preparing the databases used in this work, to Dr SL] McAllion and Ms ] Hoyal for advice on this article in draft and to the Cunningham Trustees for their support for our work on os­teogenesis imperfecta.

 

 

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