Clinica Imagenologica Dres. Parada, Montevideo, Uruguay

Definition:   Unilateral or bilateral short lower extremity due to a congenital absence of fibula, commonly associated with anterior bowing of the lower leg, with skin dimpling and anomalies of the foot.

Synonyms:  Femur-fibula-ulna syndrome^[1], intercalary hemimelia of the fibula, Fibula, congenital deficiency of proximal femoral focal deficiency, congenital short tibia with absent or dysplastic fibula

Prevalence:  M2: F1

Occurrence:  The fibula probably is the most frequently hypoplastic or absent long bone. Several hundred cases have been recorded.

Etiology:  Usually sporadic, although a familial incidence (autosomal recessive)^[2],^[3],^[4],^[5] has been reported in a small percentage of cases. Teratogens and mechanical factors have not been ruled out.

Recurrence Risk. For the patient’s siblings probably negligible, unless autosomal recessive; for patient’s child: unknown.

Pathogenesis:  Embryologic studies indicate a development insult to the embryo at about the fifth or sixth week of intrauterine life. Similar anomalies have been successfully produced in experimental animals by various chemical substances, such as busulfan, if administrated during a specific period of intrauterine development.  Tibial bowing and foot deformities are probably the result of abnormal attachments of the fibular muscles, resulting in abnormal stresses on the developing tibia and the foot, respectively.

Fibula abnormalities vary from a partial absence, with relatively normal-appearing limbs, to absent fibula, with marked shortening of the femur, curved tibia and serious foot anomalies.

Generally three types have been recognized.

• TYPE I includes cases with unilateral or partial absence of the fibula, with mild or no bowing of the tibia (10 % of the cases). The leg may or may not be shortened.
• TYPE II patients have unilateral absence of the fibula, anterior bowing of the tibia with dimpling foot deformity with absent rays, and marked shortening of the leg. This form is observed in about 35 % of the cases.
• TYPE III (the remaining 55 % of the patients) have unilateral or bilateral absence of the fibula, with the same leg and foot deformities above described and multiple other skeletal defects. Short femur of   varying degrees appears to be a frequent finding in type II and III  patients, as are talipes equinovarus or equinovalgus deformities and a tight band extending from the calcaneous to the upper portions of the tibia.

Diagnosis: The diagnosis is made by the absence of the fibula with commonly associated clubfoot^[6],^[7]. The degree of fibular deficiency ranges from unilaterally short to bilaterally absent^[8]. Other findings (see associated anomalies below) can also be diagnosed^[9].

This fetus has a small amount of bowing and shortening of the right leg (compare to the left leg on the second image):

Note the striking cross-section of both lower legs with absence of the fibula on the right leg (left on the images):

and a longitudinal view of both lower legs:

And the resulting club foot and foot hypoplasia. Note on the last image the lack of 5 toes.

And the baby after delivery

Associated anomalies: The most common associated anomaly is proximal femoral deficiency syndrome^[10],^[11].

Other anomalies includes cardiac anomalies, thrombocytopenia absent-radius (TAR) syndrome, thoracoabdominal schisis, spina bifida and renal anomalies, but most associated anomalies are skeletal and includes^[12],^[13],^[14],^[15],^[16],^[17]:

• Peromelia (severe anomalies of distal limbs including absence of hand or foot),
• congenital dislocation of the head of the radius,
• craniosynostosis⁵,
• syndactyly, brachydactyly and clinodactyly of fingers and toes,
• onycho-osteodysplasia^[18]
• facial dysmorphism,
• congenital shortening of the femur,
• distal femoral valgus with condylar hypoplasia,
• external rotation deformity.

Differential diagnosis: Amniotic band syndrome, campomelic dysplasia, fetal thalidomide syndrome, mesomelic dysplasia, skeletal dysplasia, ulna and fibula hypoplasia.

Prognosis: Rehabilitation varies depending on the severity of the limb deficiency. Prognosis is good with regard to mental development and life span.

Management: Standard obstetrical management is not altered. Fibular deficiency is usually benign, but leg length inequality may be corrected by epiphysiodesis, leg lengthening, ankle reconstruction using the Gruca technique^[19] or simply a shoe raise. Rarely when the foot is nonfunctional, amputation may be considered^[20],^[21],^[22],¹⁷.

References

^[1]Congenital absence of fibula. in Birth Defects Encyclopedia. Mary Louise Buyse (Ed.) Blackwell Publication date…)

^[2] Gupta AK, Berry M, Verma IC Congenital absence of both fibulae in four siblings. Pediatr Radiol 1994;24(3):220-1

^[3] Kohn G, Veder M, Schoenfeld A, el Shawwa  R New type of autosomal recessive short-limb dwarfism with absent fibulae, exceptionally short digits, and normal intelligence. Am J Med Genet 1989 Dec;34(4):535-40

^[4] Kumar D, Duggan MB, Mueller RF, Karbani G Familial aplasia/hypoplasia of pelvis, femur, fibula, and ulna with abnormal digits in an inbred Pakistani Muslim family: a possible new autosomal recessive disorder with overlapping manifestations of the syndromes of Fuhrmann, Al-Awadi, and Raas-Rothschild. Am J Med Genet 1997 May 16;70(2):107-13

^[5] Lowry RB Congenital absence of the fibula and craniosynostosis in sibs. J Med Genet 1972 Jun;9(2):227-9

^[6] Khurana DK, Bhargava SP Congenital absence of fibulae, with equinovarus deformity--a case report. Acta Orthop Scand 1997 Jun;68(3):307-8

^[7] Sepulveda W, Weiner E, Bridger JE, Fisk NM Prenatal diagnosis of congenital absence of the fibula. J Ultrasound Med 1994 Aug;13(8):655-7

^[8] Hootnick DR, Levinsohn EM, Packard DS Jr Midline metatarsal dysplasia associated with absent fibula. Clin Orthop 1980 Jul-Aug;(150):203-6

^[9] Rizk DE, Bates A, Evans JIsolated complex limb reduction abnormality diagnosed antenatally. Eur J Obstet Gynecol Reprod Biol 1993 Oct;51(2):163-6

^[10] Schatz SL, Kopits SE Proximal femoral focal deficiency. AJR Am J Roentgenol 1978 Aug;131(2):289-95

^[11] Pappas AM Congenital abnormalities of the femur and related lower extremity malformations: classification and treatment. J Pediatr Orthop 1983 Feb;3(1):45-60

^[12] Pivnick EK, Kaufman RA, Velagaleti GV, Gunther WM, Abramovici D Infant with midline thoracoabdominal schisis and limb defects. Teratology 1998 Nov;58(5):205-8

^[13] Stoll C, Alembik Y, Repetto M Congenital bilateral fibular deficiency with facial dysmorphia, brachydactyly and mental retardation in a girl. Genet Couns 1998;9(2):147-52

^[14] Stanitski DF, Kassab S Rotational deformity in congenital hypoplasia of the femur. J Pediatr Orthop 1997 Jul-Aug;17(4):525-7

^[15] Cuervo M, Albinana J, Cebrian J, Juarez C Congenital hypoplasia of the fibula: clinical manifestations. J Pediatr Orthop B 1996 Winter;5(1):35-8

^[16] Ray R, Zorn E, Kelly T, Hall JG, Sommer A Lower limb anomalies in the thrombocytopenia absent-radius (TAR) syndrome. Am J Med Genet 1980;7(4):523-8

^[17] Berenter R, Morris J, Yee B Bilateral congenital absence of the fibula. J Am Podiatr Med Assoc 1990 Jun;80(6):325-8

^[18] Banskota AK, Mayo-Smith W, Rajbhandari S, Rosenthal DI Case report 548: Nail-patella syndrome(hereditary onycho-osteodysplasia) with congenital absence of the fibulae. Skeletal Radiol 1989;18(4):318-21

^[19] Thomas IH, Williams PF The Gruca operation for congenital absence of the fibula. J Bone Joint Surg Br 1987 Aug;69(4):587-92

^[20] Maffulli N, Fixsen JA Fibular hypoplasia with absent lateral rays of the foot. J Bone Joint Surg Br 1991 Nov;73(6):1002-4

^[21] Maffulli N, Fixsen JA Management of forme fruste fibular hemimelia. J Pediatr Orthop B 1996 Winter;5(1):17-9

^[22] Boakes JL, Stevens PM, Moseley RF Treatment of genu valgus deformity in congenital absence of the fibula. J Pediatr Orthop 1991 Nov-Dec;11(6):721-4