Ossification of the initial cartilaginous model, which is accomplished by way of aggregation and differen- tiation of mesenchymal cells and proliferation, hy- pertrophy, and death of chondrocytes, is initiated in the collar surrounding the hypertrophic cartilage core, which is eventually invaded by blood vessels and replaced by bone tissue and bone marrow (Can- cedda et al. 2000). The primary ossification centers for the iliac bones appear around the 8th week of ges- tation, while those for the ischial and pubic bones ap- pear at the 14th to 17th week. Two other small ossifi- cation nuclei appear at the level of the posteroinferi- or and superoanterior iliac spine around the 10th and 13th weeks of gestation, respectively. The fetal development of the pelvis and acetabulum is closely related to mechanical stimuli, the most important be- ing the activity of the gluteal muscles and the simul- taneous pressure of the femoral head (Delaere and Dhem 1999). At birth, the ilia are well developed but remain widely separated from the ischia and pubic bones by the triradiate cartilages; the pubic bones are formed; the ischiopubic synchondroses are wide open; and the femoral heads are entirely cartilagi- nous (absence of ossific nuclei). At 3 months the ilia are still separated from the ischia and pubic bones, the ischiopubic synchondroses are open, the symph- ysis pubis is wide, and the ossification centers for the femoral epiphyses have not yet appeared. At 5 years the separation of the ilia from the ischia and pubic bones persists, but the ischiopubic synchondroses are almost completely closed. At 14 years the innom- inate bones are completely formed and secondary centers appear in the iliac crests and at the inferior borders of the ischia. The center for the iliac crest fuses with the iliac bone in adult life (Silverman 1993).
References
Cancedda R, Castagnola P, Cancedda FD, Dozin B, Quarto R.
Developmental control of chondrogenesis and osteogene- sis. Int J Dev Biol 2000; 44: 707–14
Delaere O, Dhem A. Prenatal development of the human pelvis and acetabulum. Acta Orthop Belg 1999; 65: 255–60 Silverman FN. Introduction to the pelvis. In: Silverman FN,
Kuhn JP (eds.) Caffey’s pediatric X-rays diagnosis.
C.V. Mosby Company, St Louis, 1993 (9th ed.), p. 175
Abnormal Shape or Size of Ilia, Ischia, and Pubic Bones
This chapter provides an overview of some common alterations of the shape and size of the human pelvis, with special reference to those encountered in the skeletal dysplasias and malformation syndromes. A significant overlap exists across the chapter, since a number of radiographic signs individually discussed in the subsequent sections are also components of more extended phenotypic spectra involving the pelvis. Emphasis has been placed on pelvic hypopla- sia, the broadest pelvic phenotype, while other de- fects have been more briefly reviewed.
As discussed in more detail below, some pelvic ab- normalities are known to be specific for a given dis- order, allowing diagnosis. The iliac horns of nail- patella syndrome and the snail-shaped pelvis of sch- neckenbecken dysplasia are remarkable examples. In several other instances, the radiographic features concerning the pelvis, although not specific, are suffi- ciently characteristic to limit the range of diagnostic possibilities.
Alessandro Castriota-Scanderbeg, M.D.
Small, Hypoplastic Pelvis
䉴
[Underdeveloped pelvis]
Pelvic hypoplasia itself is a nonspecific feature of sev- eral constitutional bone diseases. As such, it is of lim- ited diagnostic value when considered alone. Never- theless, pelvic hypoplasia is seldom ‘harmonic,’ as it is most commonly associated with changes in the pelvic shape that may provide important clues to the radiographic recognition of specific disorders. This section summarizes some of these configurations associated with pelvic hypoplasia. The disorders in which individual portions of the pelvis are hypoplas- tic are also mentioned. The topic of hypoplastic pubic rami is addressed in a separate section in this chapter.
In children with thanatophoric dysplasia (OMIM 187600) the pelvis is markedly hypoplastic, with squared iliac bones, small sacroiliac notches, hori- zontal acetabular roofs with peripheral spikes, and short and wide pubic and ischial rami. Additional ra- diographic manifestations in this early lethal bone dysplasia include marked rhizomelic limb shorten- ing, bowing of long bones (the femurs resemble tele- phone receivers), very short ribs, and severe platy- spondyly (Fryns et al. 1978). The overall radiograph- ic appearance of the pelvis may be indistinguishable from, but is usually more severe than, that of homozy- gous achondroplasia (Pauli et al. 1983; Stanescu et al.
1990). Similar but much milder findings occur in heterozygous achondroplasia (OMIM 100800). In this condition the ilia are longitudinally shortened owing to overgrowth of the body and relative undergrowth of the iliac wing with lack of normal flaring, a pattern resulting in squared-off iliac bones (Silverman 1993).
Small sacrosciatic notches, narrow sacrum, and hori- zontal acetabuli are additional features (Langer et al.
1967). In hypochondroplasia (OMIM 146000) clinical and radiographic signs are often subtle, leading to underdiagnosis. Shortening of the iliac bones, with small sciatic notches and flattened acetabuli, can be seen. The correct diagnosis is based on recognition of the following triad: normal facies, short stature, and lack of the normal craniocaudal increase in the interpediculate distance in the lumbar spine (Appan et al. 1990). Infants with asphyxiating thoracic dyspla- sia (Jeune syndrome, OMIM 208500) show squared- off iliac bones with round lateral borders and short pubic and ischial bones. The acetabular roofs are horizontal, with downward spike-like projections at the medial, lateral and – in some cases – central por- tions, giving them a ‘trident’ appearance. Sciatic
notches are small, and premature ossification of the femoral capital epiphyses occurs. These features tend to come closer to normal with increasing age (Oberklaid et al. 1977). In infants with chondroecto- dermal dysplasia (Ellis-van Creveld syndrome, OMIM 225500) the pelvis is similar in all respects to that seen in asphyxiating thoracic dysplasia and short-rib/polydactyly syndrome (Kozlowski et al.
1972) (Fig. 4.1). Hand polydactyly, a constant feature in Ellis-van Creveld syndrome and an inconstant one in asphyxiating thoracic dysplasia, may sometimes allow radiographic differentiation. In achondrogene- sis, a condition characterized by severely deficient ossification of the skeleton, the pelvis has small and deformed iliac bones, with poorly ossified or un- ossified sacrum, ischial and pubic bones. Features in achondrogenesis type IA and IB (OMIM 200600, 600972) are usually more severe than those of type II (Langer-Saldino, OMIM 200610). When it is not pos- sible to decide with certainty which of the two types is present, the identification of crescent-shaped medi-
Fig. 4.1. Chondroectodermal dysplasia in a 25-week male fe- tus. Note vertically shortened ilia, and small sciatic notches with hook-like downward projection of the medial aspects of the acetabula. This appearance of the pelvis is indistinguish- able from that of asphyxiating thoracic dysplasia and short- rib/polydactyly syndrome. (From Sergi et al. 2001)
al and inferior iliac borders makes the diagnosis of Langer-Saldino rest likely (van der Harten et al.
1988). Whether hypochondrogenesis and achondro- genesis type II (Langer-Saldino) are part of the spec- trum of severity of the same disorder (Borochowitz et al. 1986a) or represent allelic variants (Hendrickx et al. 1983) is uncertain. Mutations in the COL2A1 gene, resulting in reduction of type II collagen in the cartilage, have been identified in both disorders (Horton et al. 1987). The phenotype is much milder in hypochondrogenesis than in achondrogenesis type II. The autosomal dominant spondyloepiphyseal dysplasia congenita (OMIM 183900), another con- dition with abnormal type II collagen (Murray and Rimoin 1988; Anderson et al. 1990), represents the nonlethal counterpart of hypochondrogenesis/achon- drogenesis type II. Distinct features in the pelvis in- clude delayed ossification of the pubic bones and proximal femurs, and hypoplastic ilia. Premature os- teoarthritis of the hips may be the sole manifestation in mild cases (Kozlowski et al. 1977b). Fibrochondro- genesis (OMIM 228520), a rare lethal chondrodyspla- sia, is characterized by very short long bones with flared metaphyses, platyspondyly, thin and short ribs with cupped ends, and small pelvis, with rounded lat- eral borders and small sacrosciatic notches (Whitley et al. 1984). Severe hypoplasia and a very peculiar configuration of the pelvis is seen in schneckenbecken dysplasia (OMIM 269250) (from German, snail pel- vis). This rare and early lethal condition of auto- somal recessive inheritance is characterized by small ilia, flat and horizontal acetabula, narrow chest with short ribs, platyspondyly, large skull, short and wide fibulas, and very short tubular bones looking like dumb-bells because of their ends (Borochowitz et al.
1986b). The appearance of the iliac wings, shaped in the form of a snail, is unique to this condition
(Knowles et al. 1986; Camera et al. 1991) (Fig. 4.2).
Dyssegmental dysplasia, Silverman-Handmaker type (OMIM 224410) involves a characteristic appearance of the pelvis: the iliac bones are short, round and densely calcified (Handmaker et al. 1977). Flared ilia are typically found in the milder Rolland-Des- buquois type (OMIM 224400). Small sacrosciatic notches, and broad pubis and ischia are common to both types. In patients with metatropic dysplasia (OMIM 250600) the body proportions characteristi- cally change with age. Neonates and infants are of normal overall body length, with a disproportionate- ly long trunk and short extremities. In childhood and adulthood, a type of short-trunk dwarfism with pro- gressive kyphoscoliosis becomes apparent. Radi- ographic features in infancy include severe shorten- ing of the tubular bones, with metaphyseal widening of an extreme degree (dumb-bell appearance); elon- gated, narrow thorax; poorly ossified, broad, or dia- mond-shaped vertebral bodies; and hypoplastic pelvis, with round, crescent-shaped iliac wings, flat acetabula, and small sacrosciatic notches. In later life the tubular bones remain short, with trumpet-like metaphyses and epiphyseal dysplasia; the vertebral bodies become flat and anteriorly wedged, giving rise to progressive kyphoscoliosis; the iliac crests become markedly flared; and the capital epiphyses are very small, in contrast to the other parts of the proximal femurs, which are large and deformed (Kozlowski et al. 1977a). In metaphyseal dysplasia, McKusick type (OMIM 250250), the pelvis is uniformly hypoplastic, with shallow acetabular fossae and small inferior iliac spine (McKusick et al. 1965). Patients with Stick- ler syndrome (arthro-ophthalmopathy, OMIM 108300), a connective tissue disorder of autosomal dominant inheritance, show a marfanoid habitus, severe pro- gressive myopia, cleft palate, micrognathia, and en- larged joints (knee, wrist and ankle) at birth. Radio- logically, features include narrow diaphyses of the long bones, with thin cortices, irregular and hypo- plastic epiphyses, wide femoral neck with coxa valga, hypoplastic iliac wing, narrow sciatic notches, and flat acetabula (Opitz et al. 1972).‘Thoracopelvic dysos- tosis’ (OMIM 187770) means the association of nar- row chest and small pelvis, with a very distinctive, heart-shaped pelvic inlet (Bankier and Danks 1983).
Thoracopelvic dysostosis shares phenotypic and ra- diographic similarities with thoraco-laryngo-pelvic dysplasia (Barnes syndrome, OMIM 187760) and may represent a contiguous gene syndrome (Marik et al. 2000). Laryngeal involvement in Barnes syndrome is the distinguishing feature. An association of pelvic dysplasia and arthrogrypotic changes in the lower
Fig. 4.2. Schneckenbecken dysplasia in a 22-week male fetus.
Observe typical snail-like appearance of the right ilium, show- ing a peculiar projection of its medial portion. Same case as in Fig. 2.41. (From Nikkels et al. 2001)
limbs, or pelvic hypoplasia/lower limb arthrogryposis (OMIM 602484), has been reported in sibs (Ray et al.
1986; Sarralde et al. 1998). The pelvis shows marked hypoplasia of the iliac bones, irregular acetabula, widened triradiate cartilages, and delayed ossifica- tion of the femoral heads. Fuhrmann syndrome (OMIM 228930) is an association of fibular hypopla- sia/aplasia, severe femoral bowing, and digital anom- alies (polydactyly, syndactyly, oligodactyly) (Fuhr- mann et al. 1980). Pelvic hypoplasia and congenital hip dislocation are additional features. Fuhrmann syndrome is a separate entity distinct from Fuhr- mann dysplasia (OMIM 126950), in which tall vertebrae are the diagnostic clue. Limb/pelvis-hypo- plasia/aplasia syndrome (Al-Awadi/Raas-Rothschild syndrome, OMIM 276820), a condition with severe deficiency of the four extremities, also shows pelvic and sacral hypoplasia, deformity of the thoracic cage, and unusual facies (Al-Awadi et al. 1985; Raas-Roth- schild et al. 1988; Camera et al. 1993). Another mal- formation pattern, referred to as aplasia/hypoplasia
of pelvis, femur, fibula, and ulna with abnormal digits and nails (OMIM 601849), overlapping with Fuhr- mann and Al-Awadi/Raas-Rothschild syndromes, has been reported in four children of an inbred Muslim family from Pakistan. Skeletal abnormalities include hypoplasia of the pelvis, aplasia/hypoplasia of the ul- nas and femurs, fibular aplasia, digital abnormalities, and absent/dysplastic nails (Kumar et al. 1997). This condition also shows similarities to the femur-fibula- ulna syndrome (FFU syndrome, OMIM 228200).
Severe hypoplasia of ilia, scapulae, and clavicles are features of the pelvis-shoulder dysplasia (sca- puloiliac dysostosis, OMIM 169550), manifesting with rib anomalies, spina bifida, and inconstant eye anomalies (Kosenow et al. 1970; Elliott et al. 2000)
Fig. 4.4. Hypoplastic pelvis–facial dysmorphism–spondylope- ripheral dysplasia. Note small iliac bones, shallow acetabula, and bilateral coxa valga. The capital femoral epiphyses are also hypoplastic. Note relative shortening of the bones in the shanks relative to the femurs. (From Kitoh and Lachman 2001) Fig. 4.3 a, b. Pelvis-shoulder dysplasia in a male patient at
a7 years and b 25 years of age. Note severely hypoplastic ilia, small and dysplastic acetabula with bilateral hip dislocation, and broad, curved ischial bones. Prominent iliac crest ossifica- tion centers, not fused with the iliac bones, are apparent in b.
(From Hauser et al. 1998) a
b
(Fig. 4.3A, B). Hypoplastic pelvis, facial dysmorphism, and mental retardation have been described in a 9-year-old Japanese boy in association with a gener- alized skeletal dysplasia resembling spondyloperi- pheral dysplasia (OMIM 271700), a rare disorder presenting with short stature, platyspondyly, and brachydactyly (Fig. 4.4). Distinctive features in this case included small flared ilia, shallow acetabula, and coxa valga; cutaneous syndactyly in the hands and feet; and lack of short stature (Kitoh and Lachman 2001).
Hypoplasia of the ischial bones is an extremely rare congenital malformation, which can occur as an isolated anomaly or as a syndromic constituent in such disorders as ischiopatellar hypoplasia, ischio- vertebral dysplasia, acrofacial dysostosis syndrome of Rodriguez, and ischiadic hypoplasia with renal dysfunction, immunodeficiency, and polydactyly.
Ischial hypoplasia has been reported in association with segmental anomalies of the spine (butterfly ver- tebrae, fused vertebrae, hemivertebrae, lumbosacral agenesis). This malformation complex has been des- ignated ischio-spinal dysostosis (Nishimura et al.
1999) (Fig. 4.5). It is not clear whether this last disor- der represents a distinct entity or is part of the mal- formation spectrum of ischiovertebral dysplasia.
Ischiopatellar dysplasia (small patella syndrome, OMIM 147891), a disorder inherited as an autosomal dominant trait, is characterized by patellar hypopla- sia, ischial hypoplasia, and a variety of lower limb malformations, including ball-and-socket ankle joints, pes planus, tarsal coalition, calcaneal exos- toses, and shortening of the 4th and 5th metatarsals (Scott and Taor 1979; Azouz and Kozlowski 1997).
Ischiovertebral dysplasia is a probably autosomal dominant disorder featuring incomplete develop- ment of the ischial rami, a peculiar facies with retro- gnathia and high-arched palate, and severely pro- gressive kyphoscoliosis (Dubousset et al. 1994;
Cohen et al. 1999). The ischial rami can be hypoplas- tic or aplastic (Fig. 4.6 a, b). Only occasionally have multiple segmental anomalies of the spine been described in ischiovertebral dysplasia. Although this disorder resembles cleidocranial dysplasia, the absence of clavicular and skull defects clearly identifies patients with ischiovertebral dysplasia.
Fig. 4.5. Ischiospinal dysostosis in a 10-year-old girl. Note the total absence of ossification of the ischial rami and lum- bosacral hypoplasia. (From Nishimura et al. 1999)
Fig. 4.6 a, b. Ischiovertebral dysplasia: pelvic radiographs in (a) a daughter and (b) her grandmother. Observe defective os- sification of the ischial rami and flattened femoral heads.
(From Cohen et al. 1999,) a
b
Moreover, the ossification delay involves the ischial rami in ischiovertebral dysplasia and the pubic rami in cleidocranial dysplasia; iliac wings are not affected in ischiovertebral dysplasia, while they are narrow in cleidocranial dysplasia; finally, the capital femoral epiphyses are flattened in ischiovertebral dysplasia and are enlarged in cleidocranial dysplasia. The spinal curvature is structural, and possibly secondary to hypoplasia of the anterior portion of the vertebral bodies. Spinal cord or nerve root compression is a common complication. Other features include partial or total scapular aplasia, anomalies of the craniocer- vical junction, incomplete fusion of the posterior arches of the lumbar vertebrae, and flattened femoral heads. Distinguishing features in acrofacial dysostosis
syndrome of Rodriguez (OMIM 201170), an early lethal disorder of autosomal recessive inheritance, include severe hypoplasia of the mandible, ischial bones, and shoulder girdle, complex limb anomalies (pre- and postaxial deficiencies), and cardiac and CNS malfor- mations. This disorder shares similarities with Nager syndrome (OMIM 154400) and Genee-Wiedemann syndrome (OMIM 263750) (Rodriguez et al. 1990). Is- chiadic hypoplasia with renal dysfunction, immunod- eficiency, and polydactyly (OMIM 243340) comprises bilateral absence of the ischiadic ramus and tuberosi- ty (the acetabula are present), intrauterine growth re- tardation, microcephaly, craniofacial anomalies, hear- ing loss, hypospadias, cryptorchidism, hand and foot postaxial polydactyly, renal dysfunction, and hypo- gammaglobulinemia (Braegger et al. 1991).An associ- ation of ischial hypoplasia, tibial hypoplasia, and fa- cial abnormalities (low-set ears, short nose with long philtrum, micrognathia, and cleft palate) has been de- scribed in a girl (Nishimura et al. 1998). Additional features included short stature, cervical spine anom- alies, bowed lower legs, hypoplasia of the lesser trochanters, tibiofibular diastasis with malformed distal tibial epiphyses, clubfoot, and brachy- mesophalangy (Fig. 4.7).
Radiographic Synopsis AP projection
1. Hypoplastic, squared iliac bones; horizontal ac- etabular roofs with peripheral spikes; small sacroiliac notches; short and wide pubic and is- chial rami (thanatophoric dysplasia, achondropla- sia)
2. Hypoplastic, squared iliac bones with round later- al borders; horizontal, ‘trident’-like acetabular roofs; small sciatic notches; short pubic and is- chial bones; premature ossification of the femoral capital epiphyses (asphyxiating thoracic dysplasia, chondroectodermal dysplasia)
3. Severely hypoplastic iliac bones; poorly ossified or unossified sacrum, ischial and pubic bones (achondrogenesis)
4. Hypoplastic ilia; unossified pubic bones and prox- imal femurs (spondyloepiphyseal dysplasia con- genita)
5. Severely hypoplastic, nail-shaped iliac bones; flat and horizontal acetabula (schneckenbecken dys- plasia)
6. Short, densely calcified ilia (dyssegmental dyspla- sia)
7. Hypoplastic pelvis, with flared iliac wings; flat ac- etabula; small sacrosciatic notches (metatropic dysplasia)
Fig. 4.7. Ischial hypoplasia–tibial hypoplasia–facial abnor- malities in a 3-year-old girl. Note broad, hypoplastic ischial ra- mi, with wide ischiopubic synchondroses. There is hypoplasia of the lesser trochanters, bowing of the tibias and fibulas, tibiofibular diastasis, and abnormal tibiotarsal joints. (From Nishimura et al. 1998,)
8. Ischial hypoplasia (ischiopatellar dysplasia, is- chiovertebral dysplasia, acrofacial dysostosis, is- chiadic hypoplasia)
Associations
• Achondrogenesis type I (Parenti-Fraccaro)
• Achondrogenesis type II (Langer-Saldino)
• Achondroplasia
• Aplasia/hypoplasia of pelvis, femur, fibula, and ulna with abnormal digits and nails
• Asphyxiating thoracic dysplasia
• Campomelic dysplasia
• Cephaloskeletal dysplasia (Taybi-Linder syndrome)
• Chondroectodermal dysplasia (Ellis-van Creveld syndrome)
• Chromosome 13 trisomy syndrome (Patau syndrome)
• Chromosome 18 trisomy syndrome (Edwards syndrome)
• Chromosome 4p– syndrome (Wolf-Hirschhorn syndrome)
• Chromosome 5p– syndrome (cri-du-chat syndrome)
• Dyggve-Melchior-Clausen syndrome
• Dyssegmental dwarfism
• Fibrochondrogenesis
∑ Focal dermal hypoplasia (Goltz-Gorlin syndrome)
• Fuhrmann syndrome
• Hypochondrogenesis
• Hypochondroplasia
• Kniest dysplasia
• Hypoplastic pelvis/facial dysmorphism/spondy- loperipheral-like dysplasia
• Ischial hypoplasia/tibial hypoplasia/facial abnor- malities
• Ischiopatellar dysplasia (small patella syndrome)
• Ischiovertebral dysplasia
• Limb/pelvis-hypoplasia/aplasia syndrome (Al-Awadi/Raas-Rothschild syndrome)
• Melnick-Needles syndrome (osteodysplasty)
• Metaphyseal dysplasia (McKusick)
• Metatropic dysplasia
• Pelvic hypoplasia/lower limb arthrogryposis
• Pelvis-shoulder dysplasia (scapuloiliac dysostosis
• Schneckenbecken dysplasia
• Short rib-polydactyly syndrome type I (Saldino-Noonan)
• Spondylo-epi-metaphyseal dysplasia (Irapa type)
• Spondylo-epiphyseal dysplasia congenita
• Stickler syndrome
• Thanatophoric dysplasia
• Thoraco-laryngo-pelvic dysplasia (Barnes syndrome)
• Thoracopelvic dysostosis
• Weaver syndrome
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Ray S, Peterson PD, Scott CI Jr. Pelvic dysplasia associated with arthrogrypotic changes in the lower extremities: a new syndrome. Clin Orthop 1986; 207: 99–102
Rodriguez JI, Palacios J, Urioste M. New acrofacial dysostosis syndrome in 3 sibs. Am J Med Genet 1990; 35: 484–9 Sarralde A, Reynoso MC, Nazara Z, Soto F, Hernandez A. Pre-
natal growth retardation, pelvic hypoplasia, and arthrogry- potic changes of lower limbs: a distinct autosomal-reces- sive disorder. Am J Med Genet 75: 1998; 453–60
Scott JE, Taor WS. The “small patella” syndrome. J Bone Joint Surg Br 1979; 61: 172–5
Sergi C, Voigtlander T, Zoubaa S, Hentze S, Meyberg-Solomey- er G, Troeger J, Tariverdian G, Otto HF, Schiesser M. Ellis- van Creveld syndrome: a generalized dysplasia of enchon- dral ossification. Pediatr Radiol 2001; 31: 289–93
Silverman FN. Dysostoses, miscellaneous syndromes, and metabolic abnormalities. In: Silverman FN, Kuhn JP (eds.) Caffey’s pediatric X-rays diagnosis. C. V. Mosby Company, St. Louis, 1993 (9th ed.), p. 1581
Stanescu R, Stanescu V, Maroteaux P. Homozygous achon- droplasia: morphologic and biochemical study of cartilage.
Am J Med Genet 1990; 37: 412–21
Van der Harten HJ, Brons JT, Dijkstra PF, Niermeyer MF, Mei- jer CJ, van Giejn HP, Arts NF. Achondrogenesis-hypochon- drogenesis: the spectrum of chondrogenesis imperfecta. A radiological, ultrasonographic, and histopathologic study of 23 cases. Pediatr Pathol 1988; 8: 571–97
Whitley CB, Langer LO Jr, Ophoven J, Gilbert EF, Gonzalez CH, Mammel M, Coleman M, Rosemberg S, Rodriques CJ, Sibley R et al. Fibrochondrogenesis: lethal, autosomal recessive chondrodysplasia with distinctive cartilage histopatholo- gy. Am J Med Genet 1984; 19: 265–75
Flared Iliac Wings
䉴
[Widening of the iliac wings, with external rotation]
The overall iliac configuration varies considerably
according as whether flaring of the iliac wings is as-
sociated with constriction of the iliac supra-acetabu-
lar regions or with decreased vertical diameter of the
iliac bones and unchanged basilar portions. The first
iliac configuration is characteristic of the ‘dysostosis
multiplex,’ but also occurs to a variable extent in
atelosteogenesis, boomerang dysplasia, osteodys-
plasty, and frontometaphyseal dysplasia. The second
iliac bone configuration is seen in metatropic dyspla-
sia, dyssegmental dysplasia, spondyloepiphyseal dys-
plasia congenita, spondylometaphyseal dysplasia Ko-
zlowski type, and several other constitutional bone
disorders.
In addition to flaring of the iliac wings and con- striction of the iliac bodies, mucolipidosis II (I-cell disease, OMIM 252500) and III (pseudo-Hurler poly- dystrophy, OMIM 252600) feature shallow and de- formed acetabular fossae, tapering of the ischial bones, small and irregular femoral heads, and coxa valga (Melhem et al. 1973) (Fig. 4.8). In mucopolysac- charidosis IV (Morquio, OMIM 252300), increased
obliquity of the acetabular roofs (increased acetabu- lar angle) and marked flaring of the iliac wings are observed. The pelvic inlet shows a wine-glass-like configuration. Coxa valga and progressive dysplasia of the capital femoral epiphyses are also found (Langer and Carey 1966). In mucopolysaccharidosis III (Sanfilippo, OMIM 252900) flaring of the iliac wings is mild, the superior acetabular portion is un- derdeveloped, and the femoral necks are widened (Langer 1964). Flared ilia with hypoplasia of their inferior portion occur in atelosteogenesis I (OMIM 108720) and II (de la Chapelle dysplasia, OMIM 256050), and boomerang dysplasia (OMIM 112310) (Fig. 4.9). In atelosteogenesis II a medial spur of the acetabular border similar to that of chondroectoder- mal dysplasia, asphyxiating thoracic dysplasia, and short-rib polydactyly syndrome, may be found (Sil- lence et al. 1997). A phenotype similar to, but less severe than, that of dysostosis multiplex may be ob- served in Melnick-Needles syndrome (osteodysplasty, OMIM 309350): the iliac wings are thin and flared, with constriction at the basis of the ilium, and a sharply concave sacrosciatic notch. In addition, pubic and ischial bones are narrow (Dereymaeker et al.
1986). In frontometaphyseal dysplasia (OMIM 305620) flaring of the iliac wings is striking (Holt et al. 1972).
In Down syndrome, the iliac dysplasia consists in flared iliac wings and flattened acetabular roofs that persist into adulthood (Roberts et al. 1980) (Fig. 4.10).
Metatropic dysplasia (OMIM 156530), a disorder inherited as an autosomal recessive trait, is charac- terized in infancy by short iliac wings with curved lateral margins and small sciatic notches. Later in life, the iliac wings become severely flared, giving rise to a ‘battle-axe’ appearance: the anterior superior iliac spines sometimes approach the highest portion of the horizontal acetabulum, while the iliac bodies remain hypoplastic. Broad femoral necks and de- formed capital epiphyses are additional findings (Kozlowski et al. 1988) (Fig. 4.11). In addition to clas- sic metatropic dysplasia, a clinically and genetically heterogeneous group of bone dysplasias with similar, but milder, skeletal changes has been reported under the designation ‘metatropic dysplasia variants.’ Fea- tures common to both types include dumb-bell- shaped long bones, characteristic tongue-like projec- tions of the lesser trochanters, platyspondyly of vary- ing degree (from wafer-like vertebrae in the classic form to mild flattening in the variants), and short, broad, flared ilia with supra-acetabular notches (Nishimura et al. 1998) (Fig. 4.12). Spondylometaphy- seal dysplasia, Kozlowski type (OMIM 184252) dis-
Fig. 4.9. Atelosteogenesis/boomerang dysplasia in an 18-week fetus with a clinical phenotype overlapping atelosteogenesis I and boomerang dysplasia. Note marked flaring of iliac wing, and hypoplasia of the basilar portion of the ilium. (From Sil- lence et al. 1997)
Fig. 4.8. Mucolipidosis III in a 26-year-old man. Note flaring of the iliac wings and narrowing of the supra-acetabular iliac regions. The acetabular fossae are shallow and irregular. Irreg- ular outline of the right femoral head, with cystic lucencies, suggests avascular necrosis. There is bilateral coxa valga.
(From Wihlborg et al. 2001)
plays short and flared ilia with small sacrosciatic notches, and irregular, horizontally oriented acetabu- la. Iliac wing flaring also occurs in the mild variety of dyssegmental dysplasia, Rolland-Desbuquois type (OMIM 224400) in association with small sacrosciat- ic notches and broad pubis and ischia (Aleck et al.
1987). Mild iliac flaring is observed in spondyloepi- physeal dysplasia congenita (OMIM 183900). In this condition, however, striking features include severe delay in the ossification of the pubic bones and prox- imal femurs, progressive coxa vara, and premature osteoarthritis (Spranger and Langer 1970).
While the radiographic stigmata of nail-patella syndrome (OMIM 161200) take the form of the char- acteristic iliac horns at all ages, flaring of the iliac wings occurs in late adolescence and adulthood (Williams and Hoyer 1973).
Radiographic Synopsis
AP projection. The iliac angle is defined as the angle between the horizontal line drawn through the Y car- tilages and a line connecting the most lateral margin of the bony acetabulum and the most lateral point of the iliac wing. The definition of the acetabular angle is given in section “Small Acetabular Angle” in this chapter. The iliac index is the sum of both acetabular angles and both iliac angles, divided by 2. Standard norms for the values of acetabular and iliac angle and iliac index are available for both children and adults (Petterson and Ringertz 1991; Taybi and Kane 1968).
1. Flared iliac wings; narrowed iliac bodies (supra- acetabular constriction); shallow acetabula; nor- mal sciatic notches (mucolipidosis II–III, muco- polysaccharidosis III–IV, frontometaphyseal dys- plasia)
2. Extreme flaring of the iliac wings, with battle-axe appearance (metatropic dysplasia)
3. Hypoplastic ilia, with iliac wing flaring; small sacrosciatic notches; horizontal and irregular ac- etabular roofs (decreased acetabular angle) (spon- dylometaphyseal dysplasia, dyssegmental dyspla- sia, spondyloepiphyseal dysplasia congenita)
Associations
• Acro-cranio-facial dysostosis
• Arthrogryposis multiplex congenita
• Atelosteogenesis I
• Boomerang dysplasia
• Caudal dysplasia sequence
• De Lange syndrome
• Down syndrome
• Dyssegmental dysplasia (Rolland-Desbuquois)
• Frontometaphyseal dysplasia
Fig. 4.10. Down syndrome in an adult female patient. Observe marked flaring of the iliac wings, resembling Mickey Mouse ears. The acetabular roofs are flat, and the femoral necks show moderate valgus deformity
Fig. 4.11. Metatropic dysplasia in a 9-year-old girl. There is se- vere flaring of the iliac wings, with low-set anterosuperior iliac spines and hypoplastic basilar portions of the ilia. The capital femoral epiphyses are small and deformed, and proximal femoral metaphyses are broad and irregular
Fig. 4.12. Metatropic dysplasia variant in a girl aged 3 years and 8 months. Note marked flaring of the iliac wings, the supra-acetabular notches corresponding to the superior iliac spines, prominent lesser trochanters, short femoral necks, and platyspondyly. (From Nishimura et al. 1998)
• Melnick-Needles syndrome (osteodysplasty)
• Metatropic dysplasia
• Mucolipidosis II, III
• Mucopolysaccharidosis I-H, III, IV
• Nail-patella syndrome
• Prune-belly syndrome
• Rubinstein-Taybi syndrome
• Schwartz-Jampel syndrome
• Spondyloepiphyseal dysplasia congenita
• Spondyloepiphyseal dysplasia tarda with mental retardation
• Spondylometaphyseal dysplasia (Kozlowski)
References
Aleck KA, Grix A, Clericuzio C, Kaplan P, Adomian GE, Lach- man R, Rimoin DL. Dyssegmental dysplasias: clinical, radi- ographic, and morphologic evidence of heterogeneity.Am J Med Genet 1987; 27: 295–312
Dereymaeker AM, Christens J, Eeckels R, Heremans G, Fryns JP. Melnick-Needles syndrome (osteodysplasty). Clinical and radiological heterogeneity. Helv Paediatr Acta 1986; 41:
339–51
Holt JF, Thompson GR, Arenberg IK. Frontometaphyseal dys- plasia. Radiol Clin North Am 1972; 10: 225–43
Kozlowski K, Campbell J,Anderson B, Erken EH, Jequier S, Nel- son M, Sliman N, Sprague P, Tamaela L. Metatropic dyspla- sia and its variants (analysis of 14 cases). Australas Radiol 1988; 32: 325–37
Langer LO Jr. The radiographic manifestations of the HS-mu- copolysaccharidosis of Sanfilippo. Ann Radiol 1964; 7:
315–25
Langer LO, Carey LS. The roentgenographic features of the KS mucopolysaccharidosis of Morquio (Morquio-Brailsford’s disease). AJR Am J Roentgenol 1966; 97: 1–20
Melhem R, Dorst JP, Scott CI Jr, McKusick VA. Roentgen find- ings in mucolipidosis III (pseudo-Hurler polydystrophy).
Radiology 1973; 106: 153–60
Nishimura G, Satoh M, Aihara T, Aida N, Yamamoto T, Ozono K. A distinct subtype of “metatropic dysplasia variant”
characterised by advanced carpal skeletal age and subluxa- tion of the radial heads. Pediatr Radiol 1998; 28: 120–5 Petterson H, Ringertz H. Measurements in pediatric radiology.
Springer, Berlin Heidelberg New York, 1991, pp. 42–5 Roberts GM, Starey N, Harper P, Nuki G. Radiology of the
pelvis and hips in adults with Down’s syndrome. Clin Radi- ol 1980; 31: 475–8
Sillence D, Worthington S, Dixon J, Osborn R, Kozlowski K.
Atelosteogenesis syndromes: a review, with comments on their pathogenesis. Pediatr Radiol 1997; 27: 388–96 Spranger J, Langer LO Jr. Spondyloepiphyseal dysplasia con-
genita. Radiology 1970; 94; 313–22
Taybi H, Kane P. Small acetabular and iliac angles and associat- ed diseases. Radiol Clin North Am 1968; 6: 215–21 Wihlborg C, Babyn P, Ranson M, Laxer R. Radiologic mimics of
juvenile rheumatoid arthritis. Pediatr Radiol 2001; 31:
315–26
Williams HJ, Hoyer JR. Radiographic diagnosis of osteo-ony- chodysostiosis in infancy. Radiology 1973; 109: 151–4
Small Sciatic Notches
䉴
[Narrowing of the greater sciatic notches]
The normal appearance of the sciatic notch changes from infancy to adulthood. In normal adults the greater sciatic notch is a wide, smooth concavity of the superomedial margin of the innominate bone, enclosed between the posteroinferior iliac spine su- periorly and the ischial spine inferiorly. Sex differ- ences in the width of the greater sciatic notch, which is wider in female subjects, are well established in both fetuses and adults (Holcomb and Konigsberg 1995; Singh and Poturi 1978). In children in whom the ischial spine has not yet developed the Y-cartilage forms the inferior limit of the sciatic notch. Dysplas- tic changes of the pelvis are often associated with an abnormal appearance of the sciatic notches. Most commonly, small deep sciatic notches are found in association with underdeveloped, squared iliac bones and horizontal acetabula. There is therefore significant overlap between this section and others in this chapter. Small sciatic notches are typical features of thanatophoric dysplasia (OMIM 187600), achon- droplasia (OMIM 100800), asphyxiating thoracic dys- plasia (OMIM 208500), chondroectodermal dysplasia (OMIM 225500), fibrochondrogenesis (OMIM 228520), short rib-polydactyly syndrome type I (OMIM 263530)
Fig. 4.13. Short rib-polydactyly syndrome type III (Verma- Naumoff) in a 38-week stillborn. Observe hypoplastic iliac bones in all dimensions, flat acetabular roofs, a triangular ossi- fication defect above the lateral margin of the acetabulum, and a bony spur arising from the medial margin of the acetabulum, giving rise to a small sciatic notch. Also apparent are severe shortening of the long tubular bones and striking irregularity of the metaphyses, with bony spurs extending longitudinally.
(From Cormier-Daire et al. 2001)
and type III (OMIM 263510) (Fig. 4.13), and metatro- pic dysplasia (OMIM 156530). Narrow sciatic notch- es, in association with hypoplasia of the iliac wings and flat acetabula, are also found in Stickler syn- drome (arthro-ophthalmopathy, OMIM 108300). In dyssegmental dysplasia (OMIM 224400) small sciatic notches and broad pubis and ischia are seen. In the severe form of this condition, however, shortness of the iliac bones, which appear round and densely cal- cified, is highly characteristic (Handmaker et al.
1977).
Radiographic Synopsis AP view
1. Narrow sciatic notches; underdeveloped, squared iliac bones; horizontal acetabula (thanatophoric dysplasia, achondroplasia, asphyxiating thoracic dysplasia, chondroectodermal dysplasia, fibro- chondrogenesis, short rib-polydactyly syndromes, metatropic dysplasia, Stickler syndrome)
2. Small sciatic notches; broad pubis and ischia (dyssegmental dysplasia)
Associations
• Achondroplasia
• Asphyxiating thoracic dysplasia
• Cephaloskeletal dysplasia (Taybi-Linder syndrome)
• Chondroectodermal dysplasia (Ellis-van Creveld syndrome)
• Dyggve-Melchior-Clausen syndrome
• Dyssegmental dysplasia
• Fibrochondrogenesis
• Metatropic dysplasia
• Parastremmatic dysplasia
• Schneckenbecken dysplasia
• Short rib-polydactyly syndrome type I (Saldino-Noonan)
• Smith-McCort syndrome
• Stickler syndrome
• Thanatophoric dysplasia
• Thoracopelvic dysostosis
• Thoraco-laryngo-pelvic dysplasia
References
Handmaker SD, Campbell JA, Robinson LD, Chinwah O, Gorlin RJ. Dyssegmental dwarfism: a new syndrome of lethal dwarfism. Birth Defects Orig Artic Ser 1977; 13: 79–90 Holcomb SM, Konigsberg LW. Statistical study of sexual di-
morphism in the human fetal sciatic notch. Am J Phys Anthropol 1995; 97: 113–25
Singh S, Potturi BR. Greater sciatic notch in sex determination.
J Anat 1978; 125: 619–24
Iliac Crest Serration
䉴
[Irregularities of the iliac crest,
giving an appearance of a lace border around it]
This radiologic feature characteristically occurs in Dyggve-Melchior-Clausen disease (OMIM 223800), an autosomal recessive disorder resembling Morquio disease, first described in a family in which children were the product of an uncle–niece mar- riage (Dyggve et al. 1962). Affected children show mental retardation, short trunk dwarfism, micro- cephaly, thoracolumbar kypholordosis, restricted joint motion, clawed fingers, and a waddling gait.
Typical radiologic manifestations include platy- spondyly with ‘double-humped’ or ‘camel-humped’
end-plates; odontoid hypoplasia with atlantoaxial instability; short tubular bones with irregular meta- physes and epiphyses; and very specific findings in the pelvis, including ‘lacy’ iliac crests, short iliac wings, wide sacroiliac joints, narrow sciatic notches, wide pubic and ischial rami, wide symphysis pubis and ischiopubic synchondrosis, dysplastic acetabu- lar fossae, and lateral displacement of the femoral heads (Schorr et al. 1977; Hall-Craggs and Chapman 1987) (Fig. 4.14 a, b). Histologically, the lace-like ap- pearance of the iliac crests is caused by dystrophic ossification at the osteochondral junction, with bone tissue deposited in a wavy pattern. Within the growth plate, the columnar arrangement is lost and resting chondrocytes are excessively vacuolated, with dilated cisternae of rough endoplasmic reticu- lum and cytoplasmic inclusions. Dyggve-Melchior- Clausen disease without mental retardation is re- ferred to as Smith-McCort syndrome (OMIM 223800) (Smith and McCort 1958; Spranger et al. 1976).
Radiological and histopathologic abnormalities are identical in both diseases (Nakamura et al. 1997) (Fig. 4.15).
Another condition in which there is a lacy appear-
ance of the iliac crests is parastremmatic dwarfism
(OMIM 168400). Changes appear in the first months
of life, but do not become fully manifest until
10 years of age. Symmetrical bowing of the long
bones (from Greek, parastremmatic = twisted),
twisted thighs and shanks, severe genu valgum, short
neck, kyphoscoliosis, and contractures of major
joints are distinguishing features. Intelligence is
normal. A coarse trabeculated pattern with areas of
dense stippling is also observed. The metaphyses of long bones have a ‘flocky’ or ‘woolly’ appearance, while the epiphyses are severely deformed and radio- lucent (Langer et al. 1970).
Radiographic Synopsis AP view
1. Lace-like appearance of the iliac crests; short iliac wings; narrow sciatic notches; broad pubic and ischial bones; dysplastic acetabula; lateral dis- placement of the femoral heads (Dyggve-Melchior- Clausen disease, Smith-McCort dwarfism)
2. Lacy appearance of the iliac crests; flocky or wool- ly metaphyseal appearance; severe epiphyseal de- formation (parastremmatic dwarfism)
Associations
• Dyggve-Melchior-Clausen syndrome
• Parastremmatic dysplasia
• Smith-McCort disease
References
Cormier-Daire V, Savarirayan R, Unger S, Rimoin DL, Lach- man RS.“Duplicate calcaneus”: a rare developmental defect observed in several skeletal dysplasias. Pediatr Radiol 2001;
31: 38–42
Dyggve HV, Melchior JC, Clausen J. Morquio-Ullrich’s disease:
an inborn error of metabolism? Arch Dis Child 1962; 37:
525–34
Hall-Craggs MA, Chapman M. Case report 431: Dyggve-Mel- chior-Clausen syndrome (DMCS). Skeletal Radiol 1987; 16:
422–4
Langer LO Jr, Petersen D, Spranger JW. An unusual bone dys- plasia: parastremmatic dwarfism. AJR Am J Roentgenol 1970; 110: 550–60
Nakamura K, Kurokawa T, Nagano A, Nakamura S, Taniguchi K, Hamazaki M. Dyggve-Melchior-Clausen syndrome with- out mental retardation (Smith-McCort dysplasia): mor- phological findings in the growth plate of the iliac crest.Am J Med Genet 1997; 72: 11–7
Schorr S, Legum C, Ochshorn M, Hirsch M, Moses S, Lasch EE, El-Masri M. The Dyggve-Melchior-Clausen syndrome. AJR Am J Roentgenol 1977; 128: 107–13
Smith R, McCort J. Osteochondrodystrophy (Morquio-Brails- ford type). Calif Med 1958; 88: 55–9
Spranger JW, Bierbaum B, Herrmann J. Heterogeneity of Dyg- gve-Melchior-Clausen dwarfism. Hum Genet 1976; 33:
279–87 Fig. 4.15. Smith-McCort dysplasia in a 13-year-old boy. Note
small ilia with underdeveloped basilar portions. The iliac crests are lined by margins of increased density, giving a lacy appearance. The capital femoral epiphyses are underdevel- oped. Ossification of the ischial and pubic bones is retarded and irregular. (Reprinted, with permission, from Nakamura et al. 1997)
Fig. 4.14 a, b. Dyggve-Melchior-Clausen disease. a In a new- born the iliac wings are wide, while the basilar portions of the ilia are underdeveloped. The ischial and pubic bones are broad and somewhat irregular. Observe the thin sclerotic rim lining the iliac crests. With age, a lacy appearance becomes apparent.
bIn a 17-year-old girl an AP radiogram of the pelvis shows ir- regular,‘lacy’ iliac crests; dysplastic acetabula; lateral displace- ment of dysplastic femoral heads; short femoral necks; and wide symphysis pubis. (From Hall-Craggs et al. 1987)
a
b
Wide Interpubic Distance
䉴
[Increased distance between the pubic bones]
Both congenital and acquired causes can account for an increase in the interpubic distance. Congenital in- stances may be related to delayed ossification of the pubic bones, or to dysplasia of the pubis in the pres- ence of well-ossified pubic rami. Moreover, diastasis of the pubic bones can be found in isolation, in asso- ciation with other skeletal defects, or with genito- urinary abnormalities, including epispadias and uri- nary bladder extrophy.
Familial cases of dysplasia and/or delayed ossifi- cation of the pubic bones at the symphysis, without other abnormalities, have been described under the designation pubic bone dysplasia (OMIM 178350) (Schey and Levin 1971).
Wide interpubic distance is typical of conditions with defective and/or delayed ossification, such as achondrogenesis (OMIM 200600, 200610, 600972), hypochondrogenesis (OMIM 200610), spondyloepi- physeal dysplasia congenita (OMIM 183900), opsis- modysplasia (from Greek, delayed maturation;
OMIM 258480), and several others. Ossification of pubic bones is severely delayed in cleidocranial dys- plasia (OMIM 119600), and hypoplastic pubic bones with wide pubic symphysis may persist until adult- hood. Additional manifestations include hypoplastic iliac bones and acetabulum, coxa vara or coxa valga, deformed femoral head, and hip dislocation.
Boomerang dysplasia (OMIM 112310) is a very rare, early lethal disorder of unknown inheritance, char- acterized by short, bowed, boomerang-shaped long bones in the legs and a peculiar facies, with a broad nose and hypoplastic nares and septum. Bilateral ra- dial and fibular aplasia, iliac hypoplasia, generalized ossification delay, and absent pubic bones are also features (Kozlowski et al. 1981; Urioste et al. 1997).
The coexistence of manifestations of both boomerang dysplasia and atelosteogenesis type I (OMIM 108720) has raised the possibility that these disorders share a common etiology (Hunter and Carpenter 1991). A dysplastic pelvis, with small iliac wings, narrow sciat- ic notches, horizontal acetabula, and poorly ossified pubic bones occurs in cephaloskeletal dysplasia (Tay- bi-Linder syndrome, OMIM 210710), a very rare con- dition with severe intrauterine and postnatal growth retardation (primordial dwarfism) associated with skeletal dysplasia (Fig. 4.16). Affected children show marked microcephaly, with dolichocephaly, small re- ceding forehead, and prominent occiput; extensive malformation of the brain with mental retardation;
unusual face with large protruding eyes, flat bridge of nose, low-set ears, and absence of hair; and skeletal abnormalities in the spine (cleft vertebral arches, platyspondyly), long bones (short long bones with enlarged and irregular metaphyses, epiphyseal matu- ration delay), hands and feet (large hands and feet, brachydactyly and clinodactyly), and pelvis (Taybi and Linder 1967; Majewski and Goecke 1982). The disorder resembles Seckel bird-headed dwarfism (OMIM 210600) except for the abnormal body pro- portions and short limbs.
Associated genitourinary abnormalities and wide interpubic distance are features of the prune belly syndrome (OMIM 100100), a disorder of unknown inheritance affecting males almost exclusively. Char- acteristic manifestations include deficient abdominal musculature, urinary tract abnormalities, and bilat- eral cryptorchidism (Osler 1901). The abdominal
Fig. 4.16. Cephaloskeletal dysplasia (Taybi-Linder syndrome) in a 1-month-old baby boy. Observe hypoplastic, squared-off iliac wings, narrow sciatic notches, horizontal acetabular roofs, and unossified pubic bones. Also note long bone shortening with broadened and irregular metaphyses. (From Vichi et al.
2000)
wall is flaccid and wrinkled, resembling a prune.
Severe dilatation and tortuosity of the ureters, ureteral reflux, and defective contractility of an en- larged and elongated bladder are cardinal features.
Abnormalities involving the gastrointestinal, cardio- vascular, and musculoskeletal systems are common.
Skeletal manifestations include flared iliac wings, wide interpubic distance, hip dysplasia, pectus exca- vatum or carinatum, clubfoot, polydactyly, lower limb deficiency, and rib flaring (Berdon et al. 1977).
Genitourinary abnormalities, such as renal hypopla- sia/aplasia and vaginal atresia, also occur in the asso- ciation of renal, genital, and middle ear anomalies (OMIM 267400) (Winter et al. 1968). In Schinzel- Giedion syndrome (OMIM 269150), genitourinary anomalies (hydronephrosis, hypospadias) occur as part of a broad spectrum of skull anomalies, congen- ital heart defects, skeletal malformations, and a pecu- liar facies with severe midface retraction (Schinzel and Giedion 1978). Fraser syndrome (OMIM 219000) is a combination of acrofacial and urogenital malfor- mations, with or without cryptophthalmos (Koenig and Spranger 1986). The spectrum of anomalies includes high palate, ear malformations, hyper- telorism, laryngeal stenosis, syndactyly, dysplastic kidneys, bicornuate uterus, malformed fallopian tubes, labial fusion, and wide separation of the sym- physis pubis (Fraser 1962). Perinatal death is com- mon. A defect in the process of programmed cell death during embryology has tentatively been pro- posed to explain the persistent fusion of the eyelids, digits, and vagina (Thomas et al. 1986). The pattern of malformation in the duplication 9p syndrome in- cludes craniofacial anomalies (microcephaly, hyper- telorism, deep-set eyes, misshapen ears), limb anom- alies (hypoplastic terminal phalanges of fingers and toes, 5th finger clinodactyly, pseudoepiphyses), and other skeletal anomalies, such as defective ossifica- tion of the pubic rami, broad ischial bones, kyphoscoliosis, and delayed closure of cranial su- tures and fontanels. Affected children are short in stature and severely mentally retarded (Schinzel 1979).
Symphyseal separation, usually asymptomatic and measuring less than 7 mm, is frequently ob- served in pregnant women (Lindsey et al. 1988), in whom it is most probably a normal response to the hormones progesterone and relaxin. Reversal of the symphyseal separation to normal is obtained sponta- neously within few months after delivery. On occa- sion, the pubic changes do not regress and signs of bone erosion and eburnation associated with local pain and tenderness appear, giving rise to the condi-
tion termed osteitis pubis. Osteitis pubis is also seen in both women and men after pelvic (bladder or prostate) surgery and/or in athletes. In the latter, both chronic stress across the pubis and acute avul- sion at the site of attachment of the adductor and gracilis muscles are putative pathogenetic mecha- nisms (Koch and Jackson 1981; Wiley 1983).
Nonetheless, the cause of osteitis pubis remains un- known in most cases. Radiographic manifestations include subchondral bone irregularity with resorp- tion, sclerosis and, occasionally, osteolysis of variable degree. The condition can simulate pubic trauma, in- fection, ankylosing spondylitis, psoriatic arthritis, and hyperparathyroidism. Rupture of the symphysis pubis, with wide symphyseal separation, also occa- sionally occurs during labor and delivery. Symptoms include local pain, swelling, and tenderness, back pain, leg discomfort, and abnormal gait. Conserva- tive treatment followed by early mobilization is an adequate treatment (Dhar and Anderton 1992).
Radiographic Synopsis
AP and axial view. Normal translation movements of the symphysis pubis in the transverse and sagittal di- rections are about 1 mm, while movements in the vertical direction are about 2 mm in both sexes. Rota- tions in the frontal and sagittal planes are less than 1.5° (Walheim et al. 1984).
1. Poorly ossified or unossified pubic bones (achon- drogenesis, hypochondrogenesis, spondyloepiphy- seal dysplasia congenita, opsismodysplasia, boom- erang dysplasia, cephaloskeletal dysplasia) 2. Diastasis of the pubic bones (pubic bone dysplasia,
pubic diastasis/genitourinary anomalies)
3. Symphyseal gap <7 mm (normal symphyseal sepa- ration in pregnant women)
4. Symphyseal gap from 1 cm to 12 cm (rupture dur- ing labor, traumatic dislocation)
5. Bony irregularities, erosions, and sclerosis, with or without symphyseal separation (osteitis pubis, osteomyelitis, inflammatory diseases)
Associations
• Achondrogenesis
• Aminopterin/methotrexate embryopathy
• Boomerang dysplasia
• Campomelic dysplasia
• Caudal dysplasia sequence
• Cephaloskeletal dysplasia (Taybi-Linder syndrome)
• Chondrodysplasia punctata (Conradi-Hunermann)
• Chondroectodermal dysplasia
• Chromosome 4p- syndrome
• Chromosome dup9p syndrome
• Cleidocranial dysplasia
• Dyggve-Melchior-Clausen syndrome
• Ehlers-Danlos syndrome
• Focal dermal hypoplasia (Goltz-Gorlin syndrome)
• Fraser syndrome
• Hyperparathyroidism
• Hypochondrogenesis
• Hypophosphatasia
• Hypothyroidism
• Ischiopatellar dysplasia (small patella syndrome)
• Kniest dysplasia
• Larsen syndrome
• Opsismodysplasia
• Osteitis pubis, early
• Pregnancy
• Prune-belly syndrome
• Pubic bone dysplasia
• Pyknodysostosis
• Renal/genital/ear anomalies
• Schinzel-Giedion syndrome
• Sjögren-Larsson syndrome
• Spondylo-epiphyseal dysplasia congenita
• Spondylo-epi-metaphyseal dysplasia (Strudwick)
• Spondylo-megaepiphyseal dysplasia
• Symphyseal diastasis/genitourinary anomalies
• Trauma
References
Berdon WE, Baker DH, Wigger HJ, Blanc WA. The radiologic and pathologic spectrum of the prune belly syndrome. The importance of urethral obstruction in prognosis. Radiol Clin North Am 1977; 15: 83–92
Dhar S, Anderton JM. Rupture of the symphysis pubis during labor. Clin Orthop 1992; 283: 252–7
Fraser GR. Our genetical ‘load:’ a review of some aspects of ge- netical variation. Ann Hum Genet 1962; 25: 387–415 Hunter AGW, Carpenter BF. Atelosteogenesis I and boomerang
dysplasia: a question of nosology. Clin Genet 1991; 39: 471–
80
Koch RA, Jackson DW. Pubic symphysitis in runners. A report of two cases. Am J Sports Med 1981; 9: 62–3
Koenig R, Spranger J. Cryptophthalmos-syndactyly syndrome without cryptophthalmos. Clin Genet 1986; 29: 413–6 Kozlowski K, Tsuruta T, Kameda Y, Kan A, Leslie G. New forms
of neonatal death dwarfism: report of 3 cases. Pediatr Radiol 1981; 10: 155–60
Lindsey RW, Leggon RE, Wright DG, Nolasco DR. Separation of the symphysis pubis in association with childbearing. A case report. J Bone Joint Surg Am 1988; 70: 289–92 Majewski F, Goecke T. Studies of osteodysplastic primordial
dwarfism I: approach to a delineation of the Seckel syn- drome. Am J Med Genet 1982; 12: 7–21
Osler W. Congenital absence of the abdominal muscles with distended and hypertrophied urinary bladder. Bull Johns Hopkins Hosp 1901; 12: 331–3
Schey WL, Levin B. Familial pubic bone maldevelopment.
Radiology 1971; 101: 147–50
Schinzel A. Trisomy 9p, a chromosome aberration with dis- tinct radiologic findings. Radiology 1979; 130: 125–33 Schinzel A, Giedion A. A syndrome of severe midface retrac-
tion, multiple skull anomalies, clubfeet, and cardiac and re- nal malformations in sibs. Am J Med Genet 1978; 1: 361–75 Taybi H, Linder D. Congenital familial dwarfism with cephalo-
skeletal dysplasia. Radiology 1967; 89: 275–81
Thomas IT, Frias JL, Felix V, Sanchez de Leon L, Hernandez RA, Jones MC. Isolated and syndromic cryptophthalmos. Am J Med Genet 1986; 25: 85–98
Urioste M, Rodriguez JI, Bofarull JM, Toran N, Ferrer C,Villa A.
Giant-cell chondrodysplasia in a male infant with clinical and radiological findings resembling the Piepkorn type of lethal osteochondrodysplasia. Am J Med Genet 1997; 68:
342–6
Vichi GF, Currarino G, Wasserman RL, Duvina PL, Filippi L.
Cephaloskeletal dysplasia (Taybi-Linder syndrome: os- teodysplastic primordial dwarfism type III): report of two cases and review of the literature. Pediatr Radiol 2000; 30:
644–52
Walheim G, Olerud S, Ribbe T. Mobility of the pubic symph- ysis. Measurements by an electromechanical method. Acta Orthop Scand 1984; 55: 203–8
Wiley JJ. Traumatic osteitis pubis: the gracilis syndrome. Am J Sports Med 1983; 11: 360–63
Winter JSD, Kohn G, Mellman WJ, Wagner S. A familial syn- drome of renal, genital, and middle ear anomalies. J Pediatr 1968; 72: 88–93
Acetabular Abnormalities
The head of the femur and the acetabulum are anatomically and functionally related in such a way that changes in either component induce a response in the other. This holds true both for the immature and for the mature skeleton.
The acetabulum is cartilaginous at birth, with a Y-
shaped physeal plate (the triradiate cartilage) located
between the ilium, ischium, and pubis. The fully de-
veloped acetabulum is a hemispheric cavity made
deeper by a bony rim lining its contour, to which is
attached a fibrocartilaginous labrum. The smooth,
hemispheric head of the femur articulates with the
acetabular cavity, to which it is firmly attached by the
ligament of the femoral head. The bony surfaces of
the femoral head and acetabulum are covered with a
layer of articular cartilage. These articular cartilages,
together with the intra-articular space, form the hip
joint space as seen on frontal radiographs. The joint
space can be analyzed in adult by dividing it into
three portions, superior, axial, and medial (Arm-
buster et al. 1978). The axial and superior joint space
should be approximately half the medial joint space.
Changes in width of individual portions of the joint space are associated with specific hip diseases. For example, superior joint space loss is frequent in de- generative joint disease, while axial joint space loss is observed in disuse cartilage atrophy following paral- ysis, primary protrusio acetabuli, rheumatoid arthri- tis, and ankylosing spondylitis (Wroblewski and Charnley 1982). Axial and superior joint space can be increased in acromegaly (Armbuster et al. 1978).
Several measurements of normal osseous struc- tures of the hip have been determined, such as the acetabular and iliac angle, the angle of anteversion of the femoral neck, and the center-edge angle of Wiberg (Gulan et al. 2000; Engelhardt 1988). Some of these measurements are described in the sections be- low. Similarly, a number of bony landmarks, includ- ing the acetabular rim and line, the ilioischial and iliopubic line, and the teardrop configuration, have been identified as important radiographic signs in the diagnosis of specific disorders involving the hip.
In the following pages, two structural defects of the acetabulum – i.e., small acetabular angle and pro- trusio acetabuli – are described. Several other acetab- ular configurations, including trident-like, shallow, and steeply oblique acetabuli, are not discussed in detail but are mentioned throughout the chapter as appropriate.
References
Armbuster TG, Guerra J Jr, Resnick D, Goergen TG, Feingold ML, Niwayama G, Danzig LA. The adult hip: an anatomic study. I. The bony landmarks. Radiology 1978; 128: 1–10 Gulan G, Matovinovic D, Nemec B, Rubinic D, Ravlic-Gulan J.
Femoral neck anteversion: values, development, measure- ment, common problems. Coll Antropol 2000; 24: 521–7 Engelhardt P. The significance of the center-edge angle in the
prognosis of the dislocated hip 50 years after its initial description by Wiberg. Orthopade 1988; 17: 463–7 Wroblewski BM, Charnley J. Radiographic morphology of the
osteoarthritic hip. J Bone Joint Surg Br 1982; 64: 568–9
Small Acetabular Angle
䉴
[Horizontal acetabulum]
As already mentioned, horizontal acetabula are seen most commonly in association with hypoplastic iliac bones and small sciatic notches. This pelvic pheno- type is therefore encountered in many of the disorders discussed elsewhere in the chapter, including thanatophoric dysplasia (OMIM 187600), achon-
droplasia (OMIM 100800) (Fig. 4.17), asphyxiating thoracic dysplasia (OMIM 208500), chondroectoder- mal dysplasia (OMIM 225500), achondrogenesis (OMIM 200600, 200610, 600972), and metatropic dys- plasia (OMIM 250600). Kniest dysplasia (OMIM 156550) features small iliac bones, flat acetabular roofs, marked delay in ossification of the femoral cap- ital epiphyses and pubic bones, broad and short femoral necks, coxa vara, and hip contractures (Lach- man et al. 1975).
In children with hypothyroidism, the iliac wings can be flared or vertically shortened and the acetab- ular roofs are irregular and horizontal. The femoral heads are late appearing and are then irregularly ossified (epiphyseal dysgenesis), and flattened to a varying degree (McLean and Podell 1995). The mus- culoskeletal manifestations of the hypothyroid state are believed to be caused by diminished or absent effects that are exerted in normal conditions by the thyroid hormones on cell proliferation and differen- tiation at the level of bone and cartilage tissues. In aminopterin/methotrexate embryopathy flat acetabu- la, flaring of the iliac wings, and low iliac index are found. In addition, delayed ossification of the pubic and ischial bones occurs (Brandner and Nussle 1969). The changes about the cranial vault are strik- ing in this condition. Hypoplasia of the pelvis and horizontal acetabuli are also features of chromosome 13 syndrome (Patau syndrome). Other radiologic manifestations in this disorder include micro- cephaly, hand and foot deformities, hypoplastic ribs, and genitourinary and cardiovascular deformities (Delatycki and Gardner 1997).
Fig. 4.17. Achondroplasia in a newborn. Note horizontal ac- etabular roofs, and small, squared iliac bones, with lack of flar- ing. The greater sciatic notches are short. The ischial and pubic bones are short and broad. The proximal ends of the femurs show the characteristic oval shape
