Symposium on Common Orthopedic Problems
Congenital Deformities Sterling K. Clarren, MD.,* and David W. Smith, MD. t
Defects in morphogenesis can be recognized in 1 in 20 newborns. Sixty per cent of these infants have malformations, anomalies resulting from intrinsic problems in the developing embryonic tissues. The remaining affected newborns have deformations, abnormalities produced by uterine constraint that aberrantly molds the otherwise normal fetal tissues during the latter stages of pregnancy.s A distinction between malformation and deformation is important for family counseling and patient management. Malformations generally have a genetic or teratologic origin, deformations usually do not. Malformations are often difficult to treat both functionally and cosmetically. Deformations usually resolve spontaneously or can be corrected with molding via mild pressure toward the more desirable form. The musculoskeletal system is especially susceptible to alteration from constraint. Principal deformities include dislocation of the hip, various forms of talipes, bowing of the legs, dislocation of the knee, scoliosis, some forms of arthrogryposis, unusually shaped head, hypoplastic and/or asymmetric mandible, and torticollis. The origin, recognition, and general management of the more common congenital deformities and patterns of deformity are the subjects of this article.
Overview of Deformation Biomechanical forces are important in the morphogenesis of muscles, ligaments, cartilage, and bone. Hippocrates noted that function was an integral component of form and that physical alterations could be produced in an iiIdividual constrained for a sufficient time in a single position._ Such modifications of the body habitus are more readily From the Dysmorphology Unit, Department of Pediatrics RD-20, University of Washington School of Medicine, Seattle, Washington ':'Fellow in Dysmorphology t Professor'of Pediatrics Supported by Bureau of Community Health Services, Health Services Administration, Department of Health, Education and Welfare, Project 913; National Institutes of Health Grant HD 05961; Public Health Service Grant GM 15253; and Research fellowship grant from U.S. Public Health Service, National Institutes of Health Grant HD-004-04.
Pediatric Clinics of North America- VoL 24, No.4, November 1977
665
666
STERLING
K. CLARREN AND DAVID W. SMITH
achieved when tissues are easily pliable, in periods of rapid growth. Several societies have utilized this principle to produce aberrant form. Examples include binding the feet of high born Chinese baby girls to limit growth and molding the skulls of young Chinook Indians with leather bound wooden splints.2i Since the fetus is more pliable and grows seven times more rapidly than the infant, it is more susceptible to molding by constraining pressure. 8 Browne,l Chapple and Davidson,2 Nishimura,17 Wilkinson,23 and especially Dunn4 have contributed broadly to our understanding of the interaction in utero between fetal position and extrinsic constraining forces that produce congenital deformations. EXTRINSIC CONSTRAINING FORCES. Deformations are not observed in therapeutically aborted fetuses of 20 weeks' gestation or lessP Constraint normally develops as the fetus fills out the uterine cavity in late gestation. In the last 10 weeks of pregnancy the ratio of the fetus to amniotic fluid becomes progressively increased. Figure 1 sets forth some of the common factors resulting in fetal constraint. Uterine constraint is more likely in first born babies when the uterine muscle tone is greatest, in the unusually large fetus, or when there is a paucity of amniotic fluid. Additional constraint may be generated within the uterus or in the abdominal or pelvic cavities. Intrauterine space occupying bodies such as additional fetuses, a bicornuate uterus, or uterine fibroids may restrict fetal movement. Extrauterine compression may originate from tight abdominal musculature, especially in first pregnancies, or from bony maternal structures such as a prominent lumbar spine or a small pelvis. Maternal hypertension has also been significantly associated with fetal deformation,4 though the mechanism is unknown. FETAL POSTURE. The usual vertex presentation of late gestation maximizes the uterine space and permits the fetus to stretch and maintain a reasonably functional limb position. Increased compressive forces may lead to deformities in the normal cephalic position, but other positions are much more likely to give rise to undue restraint (Fig. 2). POSITION OF COMFORT. For the first days after birth, a baby can usu-
UTERINE COMPRESSION
INTRAUTERINE COMPRESSION
EXTRAUTERINE COMPRESSION
• uterine tone large fetuses oligohydramnios
multiple fetuses bicornuate uterus uterine fibroids
• abdominal tone prominent lumbar spine small pelvis
aberrant fetal position
+ means Figure 1.
~
OEFORMATION
increased
Deformation results from fetal constraint produced by multiple factors.
CONGENITAL DEFORMITIES
667
Figure 2. Uterine constraint occurs in late pregnancy as the ratio of fetus to amniotic fluid increases. This near term infant (A) is subjected to mild constraint but his vertex posture maximizes the uterine space and maintains reasonably functional limb positioning. (Courtesy of Peter Dunn, M.D., Bristol, England.) In contrast there is apparent increased constraint and unusual position in this fetus of 28 weeks' gestation (B).
ally be folded into his uterine position. Infants with deformities can usually be folded into an atypical bundle which reconstitutes their abnormal fetal posture. While a normal newborn would usually object to such unusual positioning, the deformed baby will prefer this posture and will often cry in protest when stretched into a more usual newborn posture. 2 By determining the position of comfort in the newborn examination, the physician may often gain insight into the origin of the deformation.
Patterns of Deformation Common deformities are described below individually. Often, however, a constrained infant presents with a pattern of deformation (Fig. 3). This is hardly surprising since one would anticipate that forces of compression might compromise growth in multiple foci. Generalized compression may occur when there is a paucity of amniotic fluid. Oligohydramnios is most commonly caused by renal agenesis, but it may also stem from chronic leakage of fluid. IB ,22 Regardless of the origin of the decreased fluid, the infant will exhibit the oligohydramnios tetrad of diminished size for gestational age, compressed face, limb deformities, and lung hypoplasia caused by thoracic compression (Fig. 4A). Other patterns of deformation are shown in Figure 4B and C. These breech positions result in a high risk for dislocation of the hip. It is readily apparent that each of these fetuses is also highly susceptible to other deformations of lower limb and craniofacies.
668
STERLING
K. CLARREN AND DAVID W. SMITH
++ ++ ++
Figure 3. A clinical association between common congenital deformities. (Adapted from Dunn, P .. M.: Proc. R. Soc. Med., 65:735738,1972.)
DEFORMITIES
compressed face deformed head mandibulor asymmetry torticollis
I'" +
+
++ +
'"'"
++ ++ ++ ++ -
++ ++ +
++ ++
++ -
++ -
""I'"
scoliosis
++ ++ -
deformed hips
++ ++ ++ -
deformed foot
++ -
- not signif; +
++ ++
++
++
++ ++ +
++
++ +
'" ++
++
~
=P < 0.05; ++ =p
Congenital Deformities Sterling K. Clarren, MD.,* and David W. Smith, MD. t
Defects in morphogenesis can be recognized in 1 in 20 newborns. Sixty per cent of these infants have malformations, anomalies resulting from intrinsic problems in the developing embryonic tissues. The remaining affected newborns have deformations, abnormalities produced by uterine constraint that aberrantly molds the otherwise normal fetal tissues during the latter stages of pregnancy.s A distinction between malformation and deformation is important for family counseling and patient management. Malformations generally have a genetic or teratologic origin, deformations usually do not. Malformations are often difficult to treat both functionally and cosmetically. Deformations usually resolve spontaneously or can be corrected with molding via mild pressure toward the more desirable form. The musculoskeletal system is especially susceptible to alteration from constraint. Principal deformities include dislocation of the hip, various forms of talipes, bowing of the legs, dislocation of the knee, scoliosis, some forms of arthrogryposis, unusually shaped head, hypoplastic and/or asymmetric mandible, and torticollis. The origin, recognition, and general management of the more common congenital deformities and patterns of deformity are the subjects of this article.
Overview of Deformation Biomechanical forces are important in the morphogenesis of muscles, ligaments, cartilage, and bone. Hippocrates noted that function was an integral component of form and that physical alterations could be produced in an iiIdividual constrained for a sufficient time in a single position._ Such modifications of the body habitus are more readily From the Dysmorphology Unit, Department of Pediatrics RD-20, University of Washington School of Medicine, Seattle, Washington ':'Fellow in Dysmorphology t Professor'of Pediatrics Supported by Bureau of Community Health Services, Health Services Administration, Department of Health, Education and Welfare, Project 913; National Institutes of Health Grant HD 05961; Public Health Service Grant GM 15253; and Research fellowship grant from U.S. Public Health Service, National Institutes of Health Grant HD-004-04.
Pediatric Clinics of North America- VoL 24, No.4, November 1977
665
666
STERLING
K. CLARREN AND DAVID W. SMITH
achieved when tissues are easily pliable, in periods of rapid growth. Several societies have utilized this principle to produce aberrant form. Examples include binding the feet of high born Chinese baby girls to limit growth and molding the skulls of young Chinook Indians with leather bound wooden splints.2i Since the fetus is more pliable and grows seven times more rapidly than the infant, it is more susceptible to molding by constraining pressure. 8 Browne,l Chapple and Davidson,2 Nishimura,17 Wilkinson,23 and especially Dunn4 have contributed broadly to our understanding of the interaction in utero between fetal position and extrinsic constraining forces that produce congenital deformations. EXTRINSIC CONSTRAINING FORCES. Deformations are not observed in therapeutically aborted fetuses of 20 weeks' gestation or lessP Constraint normally develops as the fetus fills out the uterine cavity in late gestation. In the last 10 weeks of pregnancy the ratio of the fetus to amniotic fluid becomes progressively increased. Figure 1 sets forth some of the common factors resulting in fetal constraint. Uterine constraint is more likely in first born babies when the uterine muscle tone is greatest, in the unusually large fetus, or when there is a paucity of amniotic fluid. Additional constraint may be generated within the uterus or in the abdominal or pelvic cavities. Intrauterine space occupying bodies such as additional fetuses, a bicornuate uterus, or uterine fibroids may restrict fetal movement. Extrauterine compression may originate from tight abdominal musculature, especially in first pregnancies, or from bony maternal structures such as a prominent lumbar spine or a small pelvis. Maternal hypertension has also been significantly associated with fetal deformation,4 though the mechanism is unknown. FETAL POSTURE. The usual vertex presentation of late gestation maximizes the uterine space and permits the fetus to stretch and maintain a reasonably functional limb position. Increased compressive forces may lead to deformities in the normal cephalic position, but other positions are much more likely to give rise to undue restraint (Fig. 2). POSITION OF COMFORT. For the first days after birth, a baby can usu-
UTERINE COMPRESSION
INTRAUTERINE COMPRESSION
EXTRAUTERINE COMPRESSION
• uterine tone large fetuses oligohydramnios
multiple fetuses bicornuate uterus uterine fibroids
• abdominal tone prominent lumbar spine small pelvis
aberrant fetal position
+ means Figure 1.
~
OEFORMATION
increased
Deformation results from fetal constraint produced by multiple factors.
CONGENITAL DEFORMITIES
667
Figure 2. Uterine constraint occurs in late pregnancy as the ratio of fetus to amniotic fluid increases. This near term infant (A) is subjected to mild constraint but his vertex posture maximizes the uterine space and maintains reasonably functional limb positioning. (Courtesy of Peter Dunn, M.D., Bristol, England.) In contrast there is apparent increased constraint and unusual position in this fetus of 28 weeks' gestation (B).
ally be folded into his uterine position. Infants with deformities can usually be folded into an atypical bundle which reconstitutes their abnormal fetal posture. While a normal newborn would usually object to such unusual positioning, the deformed baby will prefer this posture and will often cry in protest when stretched into a more usual newborn posture. 2 By determining the position of comfort in the newborn examination, the physician may often gain insight into the origin of the deformation.
Patterns of Deformation Common deformities are described below individually. Often, however, a constrained infant presents with a pattern of deformation (Fig. 3). This is hardly surprising since one would anticipate that forces of compression might compromise growth in multiple foci. Generalized compression may occur when there is a paucity of amniotic fluid. Oligohydramnios is most commonly caused by renal agenesis, but it may also stem from chronic leakage of fluid. IB ,22 Regardless of the origin of the decreased fluid, the infant will exhibit the oligohydramnios tetrad of diminished size for gestational age, compressed face, limb deformities, and lung hypoplasia caused by thoracic compression (Fig. 4A). Other patterns of deformation are shown in Figure 4B and C. These breech positions result in a high risk for dislocation of the hip. It is readily apparent that each of these fetuses is also highly susceptible to other deformations of lower limb and craniofacies.
668
STERLING
K. CLARREN AND DAVID W. SMITH
++ ++ ++
Figure 3. A clinical association between common congenital deformities. (Adapted from Dunn, P .. M.: Proc. R. Soc. Med., 65:735738,1972.)
DEFORMITIES
compressed face deformed head mandibulor asymmetry torticollis
I'" +
+
++ +
'"'"
++ ++ ++ ++ -
++ ++ +
++ ++
++ -
++ -
""I'"
scoliosis
++ ++ -
deformed hips
++ ++ ++ -
deformed foot
++ -
- not signif; +
++ ++
++
++
++ ++ +
++
++ +
'" ++
++
~
=P < 0.05; ++ =p
