ANTHROPOMETRY AND TRAUMATOLOGY OF THE PELVIS OF CHILDREN

by G . Stürtz

Daiml e r - Benz AG, Stuttgart , Germany

ABSTRACT

In the c a s e of child road users the p elvi s shows the lowe st r i sk of inj ury compar e d to o ther b o dy regions . Be ing also l o c a t e d near to the b o dy ' s centre of gravity , the pelvis i s particularly sui t ab l e for the diver sion of mass forc e s .

For this reason , an analy s i s will be given o f the traumat o l o gy , the b i ome chani c s and e sp e c i a l ly the anthropometry of the child ' s pelvi s , taking the following i t ems into considerat ion :

o typ i c al contact region of exterior road users under lat eral l o a d

o contact region o f r e s trained p a s senger car o c cupant s under frontal load

o g e ometri cally r e levant constru c t i on in the case of anthropome tric dununi e s .

Using frontal ( anterior - p o s t erior ) and lat eral X-ray phot o graphs of the p elvi s with children - given by p o s t mort em examinations - , the typ i c a l geometry o f the pelvis depending on phy s i o lo g i cal age is d e duc e d . In addi tion to thi s , the s e r e su l t s are compared with data of anthrop ome t r i c dummi e s .

Furthermore , an analy s i s o f the traumat o logy o f the child ' s p e lvis· is carr i e d out wi th r egard t o. typ e , s everi ty and r i sk of injur i e s b a s e d o n in-depth s ingle - c a s e analys e s of r e a l road a c ci dent s . The aim of thi s i s to improve the understanding of the sp e c ial injury me chani sms of this b o dy region r e s p e c t ively t o round off the l evel of knowl e dg e by d e s cribing the general biomechani c s o f the p e lvi s .

INTRODUCTI ON

The traumat o l o gy of road a c c i dents shows that the child ' s pelvis region is marked by a low r i sk of injury ( 1 ) . Part i cularly in the c a s e of child p e d e s tr ians ( 1 ) i t b e comes apparent that among the body r e gi ons in que s t ion s truck by a blunt l a t eral load at the same imp a c t sp e e d , the Relat ive Trauma t i c �egr e e ( combination of injury fre quency and inj ury s everity ) of the p e lvis r egion i s lowe s t .

Therefore this region i s o f s·p e cial importan c e :

o a s a lat eral conta c t area t o be aimed for in the c a s e o f p e d e s trians and , t o some ext ent , a l s o two -wh e e l - r i ders

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o a s a front al contact zone for a lap belt for older chi l dren

o with r e gard t o the de s ign o f anthropomet r i c dummi e s .

TRAUMATOLOGY

In order t o demonstrate the sp e c ial injury mechani sms o f the pelvis region, the trauma t i c degree a s well a s the s ever i ty and type of injur i e s ob s erve d are explained in the following .

On the b a s i s of in-depth s ingle - ca s e analy s e s of r e a l road a c c ident s in which children were involve d , i t turns out conc erning the degree of endangerment ( Tr auma t i c Degr e e ) compared to o ther b o dy regions , the pelvis region can be c l a s s i f i e d a s follows :

o in the c a s e o f p e d e s tr i ans ( 1 ) approx . r ank 8

o in the case of re strained and unr e strained c ar o c cupant s ( 1 ) appro x . rank 9 r e sp e c t ively 5

o in the c a s e of two -wh e e l -riders ( 2 ) approx . rank 5

The severity degree of the injur i e s caused t o children i s on average appro x . AIS 2 ( J ) for p e d e s t r i ans , AIS 1 for r e s trained p a s s enger c ar o c cupant s , appro x . AIS 2 for unr e s trained o c cup ant s ( 1 ) and AIS 1 to 2 for two-whe e l -r i ders ( 2 ) .

Among 49 c a s e s wi th injur i e s of the pelvis r e g i o n , the maj or i ty , i . e . 2 9 children , had soft t i s sue injur i e s , and the !arger part of the s e ( n = 2 3 ) suffered brui s e s and , in some c a s e s , haematoma s . P elvic bone injur i e s have b e en o b s erve d in 1 9 c a s e s a s follows :

o in e i ght c a s e s a pub i s frac ture and of the s e one c a s e with bur st of the symphy s i s ( AIS 2 to J )

o in four c a s e s a p e lvis girdle fracture , o f t h e s e two c a s e s with j o int p an p ar t i cipat ion ( AIS J )

o in four c a s e s a palm frac ture ( AI S 2 ) o and in thr e e c a s e s an i s chial fractur e , two c a s e s o f the s e

from type o f a doub l e fra c ture ( AI S J )

BIOMECHANI C S

A d e s cription of some facts o f t h e general b i ome chani c s of the pelvis is added to round off the l evel of knowl e dg e of thi s b o dy region . The child pelvis i s r elat ively soft and smal l and up to the age o f 10 no i l i a c spinae have yet devel op e d ( 4 ) . The rounded p elvi s palms , t o ge ther wi th the thick sub cutaneous t i s sue , produ c e a negat ive submarining effect o f the child ' s pelvis and urogenital region under a lap b e l t ( 5 ) . Thi s i s only partly comp ensat e d for by the lordo s i s of the lumbar vertebrae .

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DERIVATION OF CHILD PELVIS GEOMETRY

Using frontal ( anterior - p o s t erior ) and lat eral X-ray photographs of the infant pelvis ( sour c e s : Hannover Medical Univers ity , Institute for Forensi c Medic ine o f Heidelberg University ) from p o s t mortem examina t i ons , the typ i cal geometry of the p elvi s can be derived depending on physiologi cal age .

Ten children b e tween 2 , 1 0 and 1 1 , 8 years of age are documented ( se e F i gure 1 ) . In order t o a s s e s s the p o s it ion of the children examined in the general spe c trum , apart from s e x , the following data have been r e corded :

Body mas s Height S i t t ing height Circumference o f ehe st Circumference o f upper arm Circumference of wri s t Circumference o f c alf

The knowle dge o f the s e anthropometric data and the use of rel evant l i t erature ( 6 ) ( 7 ) make s it p o s s ib l e to derive a physiologi cal age ( 8 ) whi ch describes the state of phy s i cal development ( growth and shap e ) and who s e mean value - as c al culat e d from th� two sour c e s -i s g i ven in F i gure 1 . As a r e sul t , the age group t o b e exam·ined r e a che s from approx . 2 , 10 to 1 q , 5 years of age .

To c a l culat e the enlargement of the p e lvis image or part thereof on the X-ray pho t ograph s , the following s e t t ing data for the X-ray equipment have been r e g i s t er e d in addit ion :

Distanc e b e tween focus and obj e c t Distance b e tween focus and plate Di s t ance b e twe en focus and film

F i gure 2 provi d e s a frontal and l at eral view of the do cument ed p elvis regions . The following geometrically s i gnificant dimens ions ( se e a l s o F i gure J ) - do cumented in Figure 1 - c an be derived from thi s view :

YB lateral width of the p elvic brim

lateral d i st ance b etween the anterior sup erior i l i a c cre s t s

lateral c l e arance between the tuber o f the i s chium

ant erior/p o s t erior di stance b etween ant erior sup er i or i l i a c c r e s t and sacrum

ver t ic a l di s tance b etween tubers o f the i schium and proximal p elvi s p alms

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ver t i cal distance b etween tubers o f the i schium and ant erior sup erior iliac crest

RESULTS

From Figure 2 can b e taken , that the rounded p elvis p alms respe c t ively the not or incomp l e t e develop e d iliac sp inae produce a negat ive submarining effect under a lap b e l t the younger the children are .

A de s crip t i on of the derived anthropometric data of the p elvis region versus physiologi cal age is given in Figure J . Since the individual c a s e s are no t s cattered linearly over the physiologi cal age , it has not b e en po s sible to supply dat a dir e c t for every a g e group . For this reason, linear regress ion analy s e s have b e en carried out ( correla t �on co effic i ent s 0 , 8 3 - 0 , 96 ) which make it p o s s ible t o read off charac t e r i s t i c anthropometr i c p elvi s data of 3 - , 6 - and 10-year-old dhi ldren a s shown in Figure 4 . Figure 3 and 4 also contains the r e sp e ctive data of anthropome tric dummi e s , namely of the Alderson VIP Je and 6 c who s e p elvi s r egion is also shown in Fi gure 2 lat erally and in a/� view. In addi t i on Figure 3 shows the charat eristic data of the Hybrid I I dummy .

The geometrical dimensions of the p elvis o f chil d dummi e s differ s l ightly or consi derably from tho s e of the do cument e d chil dren. For instanc e , the ver t ical he ight o f the p e lvis ( zTp ) a s well a s the a/p distance between ant erior sup erior i l i a c crest and sacrum ( xcs > i s considerably greater in the dummi e s , whereas the l at eral distance be tween the ant erior sup erior iliac cre s t s (yc ) i s in some c a s e s much too small .

In the c a s e of the child dummi e s di s cus s e d here , the lower . pe lvi s region ( tubers of the i s chium , lower r egion of the p elvis palms ) i s not shap e d anthropometri c al ly . As c ompared t o r eality p o s i t i oning o f a lap belt and compre s s ion in the seat area i s exp e c t e d t o b e different a s well a s there i s no frontal support in the lower region of the p e lvi s palm s .

DISCUSSION

The analys i s o f traumatology o f the p e lvis r egion of infants shows that the p elvi s region app ears to be more suitabl e for the diver s ion of IDCl S S for c e s than o ther body regions in the cas e that there is no great surfac e loading .

Using a lap belt it has to b e concidered that the not or incomp l e t e develop e d iliac spinae produce a negat ive submarining effect under a lap belt .

In some items the construction of the p elvis region with dummie s do e s not corre spond t o that o f children. In d i s t inction t o the adult dummy ( Hybri d II ) , the p elvis of the child dummy is only imp erfectly de s igne d . Consequently , drawbacks in s imulat ion quality must be exp e c t e d due to the partly l imited repr e sentat ivity o f the actual d e s ign o f the p elvis region.

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REFERENCES

1 . Stürtz , G . : "Das Kind im Verkehrsunfal l : Biomechanik , Anforde ­rungen an die Äußere und Innere Si cherh e i t von Kraftwagen " . For t ­s chr i t t -Berichte der VDI -Z e i t s chriften , Reihe 1 7 , Nr . 8 , Düs s e l ­dorf 1 98 1

2 . Stürtz , G . , Suren , E . G . , Got z e n , L . , Behrens , S . , Richt er , K . : " Kop f - , Hal s - und Wirbel säulenverletzungen und Tode sur s a chen b e i Äußeren Verkehr s t e ilnehmern'� Pro c . 2nd Int . Conf . o n Biomechan i c s o f S erious Trauma , IRCOB I , Birmingham , Eng l and , Sep t . 1 9 7 5

3 . Jo int Commi t t e e o f AMA; SAE & AAAM : �The Abbrevi a t e d Inj ury S c a l e ( A I S ) 1 9 76 , Revi s i on , AAAM , Morton Grove , I l l i no i s , USA , 1 9 76

1 4 . Has s l e v , N . O . , Due , O . , Hir dt o , J . , Torgersen, R . N . : " Ch i l dren in Car s " . Department s Offs e t c entral , Sto ckholm 1 9 76 , Nordi sk Trafiksikkerheds Rad , Rep . 1 1A

5 . Stür t z , G . : "Biome chanical Data o f Chi l dr en " . Pro c . 2 4 th Stapp Car Crash Conf . , Troy , Michigan , USA , Oct . 1 980

6 . Documenta Geigy : "Wi s s ens chaftl i che Tab e l l en " . IR Geigy A . G . Pharma , Bas el , Schwe iz , 7 . Edition

7 . Snyder , R . G . : "Anthropometry o f U . S . Infants and Chi l dren " . SAE Automotive Engineering Congre s s and Exp o s i t i o n , Detro i t , Michigan , USA , Feb . 1 9 75 , Pap er 75 0 4 2 3

8 . Tanner , J . M . : "Wachstum und Reifung des Menschen " , Georg Thieme Verlag , Stuttgart , 1 962

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Regr e s sion analy s e s of character i s t i c g e ome trical pelvi s data versus phy s io l o gi cal age - ·---- - ·-- . -

Chilqren Jyears VIP Je 6years VIP 6c 10 years

Ya 152 - 147 173 - 188 199

Yc 1 3 9 - 100 157 - 1 50 182

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xcs 107 "" 1 3 7 126 - 160 150

zTD 93 - 105 102 - 1 1 9 1 1 3

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Charac t e r i s t i c geome trical pe lvi s data o f the 3 - , 6 -and 10-year-old chi ldren a s we l l a s the r e s p e c t ive data of anthropome tric dumm i e s