Fetal Fibular Hemimelia Case Report and Review of the Literature

Transcription

1 Case Report Fetal Fibular Hemimelia Case Report and Review of the Literature na Monteagudo, MD, Ran Dong, RDMS, Ilan E Timor-Tritsch, MD The IUM Practice Guideline for the Performance of an ntepartum Obstetric Ultrasound Examination 1 recommends documenting the presence or the absence of the fetal extremities during the second trimester of pregnancy. t times both upper and lower extremities may be present, and an obvious fetal malformation may not be apparent until all the long bones are carefully measured and evaluated. This can further be challenging when only 1 limb or part of a limb is affected. In the obstetric literature, there are only a handful of case reports dealing with the prenatal diagnosis of fibular hemimelia (FH; or longitudinal deficiency of the fibula or postaxial hypoplasia of the lower extremity) as an isolated finding or as part of a syndrome. 2 9 Typically, it has been diagnosed at birth, when the neonate is seen to have lower limb shortening, a foot deformity (missing 1 or 2 of the lateral toes), or both. However, in the orthopedic literature, there are many case series dealing with the surgical treatment of this entity. We report a case of FH diagnosed prenatally during a routine anatomic survey. Case Report bbreviations FH, fibular hemimelia Received December 12, 2005, from the Department of Obstetrics and Gynecology, New York University School of Medicine, New York, New York US. Revision requested January 1, Revised manuscript accepted for publication January 13, ddress correspondence to na Monteagudo, MD, Department of Obstetrics and Gynecology, New York University School of Medicine, New York, NY US. ana.monteagudo@med.nyu.edu Video online at 27-year-old woman with an uncertain last menstrual period dated by a first-trimester scan was referred for an anatomic survey at 21 weeks. First-trimester screening using nuchal translucency as well as free β-human chorionic gonadotropin and pregnancy-associated plasma protein- levels performed at a different institution had lowered her age-related risk for trisomies 21 and 18. The anatomic survey was remarkable for the right tibia, which was shortened and bowed, measuring 23.9 mm (consistent with 17 weeks gestation). On further assessment of the right lower extremity, it was noted that the right fibula was absent; the right foot had the talipes equinovalgus malformation (the clubfoot was plantar flexed, everted, and abducted); not all the metacarpal bones could be identified; and there seemed to be syndactyly of the fourth and fifth toes (Figures 1 3). The right femur measured 37.2 mm, consistent with dates. The long bones of the left lower extremity all measured within the normal 2006 by the merican Institute of Ultrasound in Medicine J Ultrasound Med 2006; 25: /06/$3.50

2 Fetal Fibular Hemimelia Figure 1. Right and left lower legs., The right lower leg shows the abnormally angulated tibia and the absence of the laterally placed fibula., The normal tibia and fibula of the left leg are shown. limits for gestational age (femur, 38.1 mm; tibia, 33.2 mm; and fibula, 32.4 mm). Three- and 4- dimensional sonography were performed, which were decisive in correctly diagnosing the outward deflection of the foot and the structure and shape of the bones involved (Figures 4 and 5 and Videos 1 and 2). ll long bones of the upper extremities were within normal limits for gestational age (right: humerus, 34.3 mm; ulna, 32.7 mm; and radius, 28.2 mm; left: humerus, 34.9 mm; ulna, 31.2 mm; and radius, 28.1 mm). In view of the absent right fibula, bowed tibia, and abnormal foot, the prenatal diagnosis of right FH was made, most likely type II. The couple received genetic counseling, and amniocentesis was performed, which revealed a normal amniotic fluid α-fetoprotein level and a normal female karyotype. fter extensive risk-benefit counseling, the pregnancy was continued. female neonate was delivered at term (Figure 6). Postnatally, the diagnosis of right FH was confirmed by radiographs of the lower extremities. The infant subsequently began undergoing conservative orthopedic correction of the defect. Discussion Development of the fetal upper and lower extremities has been documented by sonography. 10 On sonography, the lower limb buds are imaged before the upper limb buds. However, both the upper and lower buds are seen by the end of the eighth postmenstrual week of pregnancy. Subsequently, there is rapid growth of both upper and lower extremities, and, by the end of the 10th postmenstrual week, the entire Figure 2. The feet., The right foot is shown with the talipes deformity (outward deflection)., The normal left foot is shown with the appropriate relationship to the tibia and fibula. 534 J Ultrasound Med 2006; 25:

3 Monteagudo et al Figure 3. oth legs. The right tibia is bowed, and the fibula is missing. limbs are developed. Fetal movements are first imaged in the upper extremities, but movements of both the upper and lower extremities are evident only by the 10th postmenstrual week. With 4-dimensional sonography, these early fetal movements can be documented. The fetal long bones can be evaluated and measured by the end of the first trimester (10th 12th week). 11,12 In a selected high-risk patient population scanned transvaginally between 12 and 16 weeks, ronshtein et al 13 found the incidence of skeletal anomalies to be 0.57% (42 cases in 7325 scans). In contrast, the frequency of these anomalies in the general population is extreme- Figure 4. Three-dimensional rendering of the legs. The right leg is shown to be shorter and bowed, and the right foot deformity is shown. ly low. This discrepancy may be due to the fact that their patients were high risk and also due to the fact that fetuses affected by skeletal dysplasia are at an increased risk for intrauterine death. Fibular hemimelia or absence of the fibula is a rare disorder. It has been estimated that there are approximately 5.7 to 20 cases per 1 million births. 14 Fibular hemimelia in most cases represents an apparently isolated and sporadic event. 15 However, FH may be part of a malformation syndrome. Even though this is a rare condition, among the long bone deficiency disorders, it is the most common malformation. 16 Fibular hemimelia is actually a clinical spectrum ranging from mild fibular hypoplasia to fibular aplasia. The complete form is more common than the incomplete form; unilateral involvement is more common than bilateral; and the right side is more commonly affected than the left. 15,17 ilateral FH is seen in approximately one third of cases. In these cases, the tibiae are often straight. When FH is unilateral, the right side is more commonly affected, and anterior tibial bowing is usually present. In almost all cases, there is deficiency of the lateral foot rays. Less commonly, there is fibular aplasia with a normal number of toes, but almost never is it associated with polydactyly. It is twice as common in male fetuses as in female fetuses. The precise etiology of FH is unclear. However, several theories have been suggested, such as defects in the apical ectoderm ridge, defects secondary to an absent anterior tibial artery, and defects in muscle development nother proposed theory is that of a disruption of the lower limb developmental field during embryogenesis. 15 The developmental field of the lower extremity includes the pubic portion of the pelvis, proximal femur, patella, anterior cruciate ligament, and lateral or axial foot rays. 15 This developmental field encompasses the commonly associated defects seen with FH, namely, defects of the femur and lateral aspect of the foot. The femur anomalies include congenital femoral shortening, proximal focal femoral deficiency, coxa vara (abnormal angulation of the neck of the femur in relationship to the shaft of the femur), and developmental dysplasia of the hip. 18 The femur anomalies contribute to the overall limb length discrepancy seen in these cases. There several classifications of FH; however, the more commonly used is that of chterman and Kalamachi, 22 which was derived from clini- J Ultrasound Med 2006; 25:

4 Fetal Fibular Hemimelia cal as well as radiographic information. In this classification, the congenital deficiencies of the fibula were divided into 2 types. In type I, there is minimal hypoplasia of the fibula, and in type II, there is complete absence of the fibula. ccording to the chterman and Kalamachi classification, our case fell into type II. The therapies for FH are surgical and include limb-lengthening procedures and amputation. The decision to proceed with one or the other is usually individualized from case to case, but in cases in which there is a nonfunctional foot or a limb length discrepancy of greater than 30%, surgical amputation with early use of a prosthesis is generally recommended. 18 Figure 5. Three-dimensional evaluation of the legs. The images have undergone post processing. With the use of the magic cut option ( and ), redundant portions were trimmed off except for the fetal legs., Frontal view of the legs., Dorsal view of the legs. The right leg is on the right side of the image. C, With the x-ray mode with maximum intensity, the bones are highlighted. The left leg shows both the tibia and the fibula, whereas in the right leg (on the left side of the image), the bowed tibia with the outwardly deflected right clubfoot is seen. C 536 J Ultrasound Med 2006; 25:

5 Monteagudo et al 7. Capece G, Fasolino, Della Monica M, Lonardo F, Scarano G, Neri G. Prenatal diagnosis of femur-fibula-ulna complex by ultrasonography in a male fetus at 24 weeks gestation. Prenat Diagn 1994; 14: Elejalde R, De Elejalde MM, ooth C, Kaye C, Hollison L. Prenatal diagnosis of Weyers syndrome (deficient ulnar and fibular rays with bilateral hydronephrosis). m J Med Genet 1985; 21: Geipel, erg C, Germer U, Krokowski M, Smrcek J, Gembruch U. Prenatal diagnosis of femur-fibula-ulna complex by ultrasound examination at 20 weeks gestation. Ultrasound Obstet Gynecol 2003; 22: Figure 6. The size discrepancy between the 2 lower legs is evident, as well as the foot deformity. Our case had several of the typical features of FH, namely, complete unilateral absence of the right fibula with a bowed tibia and deficient lateral toe rays. However, this case was unusual in that the fetus was a girl, and this defect is twice as common in boys compared with girls. In addition, this case was unusual because we relied heavily on 3- and 4-dimensional sonography to better image and characterize the defect. References 1. merican Institute of Ultrasound in Medicine. IUM Practice Guideline for the Performance of an ntepartum Obstetric Ultrasound Examination. Laurel, MD: merican Institute of Ultrasound in Medicine; vailable at: 2. bel DE, Hertzberg S, James H. ntenatal sonographic diagnosis of isolated bilateral fibular hemimelia. J Ultrasound Med 2002; 21: Camera G, Dodero D, Parodi M, Zucchinetti P, Camera. ntenatal ultrasonographic diagnosis of a proximal femoral focal deficiency. J Clin Ultrasound 1993; 21: Hirose K, Koyanagi T, Hara K, Inoue M, Nakano H. ntenatal ultrasound diagnosis of the femur-fibula-ulna syndrome. J Clin Ultrasound 1988; 16: Sepulveda W, Weiner E, ridger JE, Fisk NM. Prenatal diagnosis of congenital absence of the fibula. J Ultrasound Med 1994; 13: Uffelman J, Woo R, Richards DS. Prenatal diagnosis of bilateral fibular hemimelia. J Ultrasound Med 2000; 19: Timor-Tritsch IE, Farine D, Rosen MG. close look at early embryonic development with the high-frequency transvaginal transducer. m J Obstet Gynecol 1988; 159: Timor-Tritsch IE, Monteagudo, Peisner D. High-frequency transvaginal sonographic examination for the potential malformation assessment of the 9-week to 14- week fetus. J Clin Ultrasound 1992; 20: De iasio P, Prefumo F, Lantieri P, Venturini PL. Reference values for fetal limb biometry at weeks gestation. Ultrasound Obstet Gynecol 2002; 19: ronshtein M, Keret D, Deutsch M, Liberson, ar Chava I. Transvaginal sonographic detection of skeletal anomalies in the first and early second trimesters. Prenat Diagn 1993; 13: Florio I, Wisser J, Huch R, Huch. Prenatal ultrasound diagnosis of a femur-fibula-ulna complex during the first half of pregnancy. Fetal Diagn Ther 1999; 14: Lewin SO, Opitz JM. Fibular a/hypoplasia: review and documentation of the fibular developmental field. m J Med Genet Suppl 1986; 2: Coventry M, Johnson EW JR. Congenital absence of the fibula. J one Joint Surg m 1952; 34: O Rahilly R. Morphological patterns in limb deficiencies and duplications. m J nat 1951; 89: Fordham L, pplegate KE, Wilkes DC, Chung CJ. Fibular hemimelia: more than just an absent bone. Semin Musculoskelet Radiol 1999; 3: O Rahilly R, Gardner E. The timing and sequence of events in the development of the limbs in the human embryo. nat Embryol (erl) 1975; 148: ohne WH, Root L. Hypoplasia of the fibula. Clin Orthop Relat Res 1977; Packard DS Jr, Levinsohn EM, Hootnick DR. Most human lower limb malformations appear to result from postspecification insults. Prog Clin iol Res 1993; 383: chterman C, Kalamachi. Congenital deficiency of the fibula. J one Joint Surg r 1979; 61: J Ultrasound Med 2006; 25: