Prenatal differential diagnosis of congenital lower extremity shortening

prenatal diagnosis
prenatal diagnosis


Abnormalities of lower extremities are extremely rare and although in many cases diagnosis is obvious, counselling is always a problem. Fibular hemimelia with an incidence of 20 cases in one million people and Tibial Hemimelia with an incidence of 1 per million is a diagnosis. This article offers a brief review of congenital lower extremity shortening, which will help healthcare professionals in counselling future parents and improving their knowledge.


Table of Contents:

1. Introduction

2. Discussion

3. Conclusions


1. Introduction

Congenital lower extremity shortening can involve any of the leg bones and joints and leads to leg length discrepancies that can result in severe lifelong morbidity and compromised ambulation.

The most common abnormalities include fibular hemimelia (FH) and proximal focal femoral deficiency. Tibial hemimelia (TH) and involvement of other bones are very rare. The spectrum of congenital lower limb shortening begins with mild forms where there is only mild hypoplasia of a bone and ends with the most severe where the bone is absent in its entirety.

International guidelines on the fetal ultrasound examination in pregnancy [1, 2] recommend documenting the presence or the absence of the fetal extremities during the second trimester of pregnancy and encourage detailed fetal limb evaluation. Therefore, severe congenital extremity shortening of arms or legs can be diagnosed as early as 20 weeks of pregnancy offering the possibility of antenatal counselling and planning.

This article focuses on congenital lower extremity shortening, reviews the most common ultrasound findings of lower limb hemimelia and discusses their prenatal differential diagnosis.


2. Discussion

Fibular hemimelia

Fibular hemimelia is the most common long bone deficiency with an incidence of 20 per million cases in postnatal series [3] but is rarely diagnosed prenatally. The ultrasonographic features are complete or almost complete absence of the fibula, marked anteromedial bowing of the tibia with a skin dimple at the point of maximum angulation, talipes equinovalgus and absence of one or more of the lateral metatarsal rays [4, 5]. Approximately 80% of the cases have unilateral involvement, usually on the right side [6]. There is considerable association between the fibular shortening and other foot abnormalities, especially shortening and bowing of the tibia, club foot or equinovalgus and femoral deformities, which are not always detectable antenatally. [Fig. 1, Fig. 2].

The etiology of FH is unknown but most cases are considered to be sporadic and with no genetic background. Pallavee et al., reported a case where FH was diagnosed following prenatal misoprostol use in the first trimester. [7]


Tibial hemimelia

Longitudinal reduction defect of the tibia is very rare, with an incidence of 1 per million in postnatal series [8]. Tibial hemimelia is characterized by deficiency of the tibia with relatively intact fibula and it may present as an isolated anomaly or be associated with a variety of skeletal and extra skeletal malformations. Tibial hemimelia may also constitute a part of a more complicated malformation complex or syndrome [9]. Prenatal diagnosis has been reported for both isolated [10, 11] and syndromic [12]. Whenever a foot abnormality has been diagnostic a full checkup of the baby is necessary involving 3D/4D scanning, assessing of the face. [17, 19] Tibial hemimelia has also been reported in twins [13]. The recognized ultrasonographic features are absent or severe shortening of the tibia, with intact fibula and abnormal feet with varus deformity.

Tibial hemimelia may be associated with a variety of skeletal and extra skeletal malformations such as polysyndactyly, club hand, radioulnar synostosis, bifid femur, cleft lip/palate and imperforate anus. Tibial hemimelia may also constitute a part of a malformation complex or syndrome such as the Gollop-Wolfgang complex and tibial agenesis-ectrodactyly, triphalangeal thumb-polysyndactyly, tibial hemimelia/split-hand/split-foot and Langer-Giedion syndromes [14,15].

Compared with other condition, like body stalk anomaly that can be picked up in first trimester, with lower congenital anomaly that might be quite difficult. [18]. Although TH is usually considered sporadic, there are several reported affected families with either autosomal dominant inheritance with great variability and reduced penetrance or an autosomal recessive pattern with or without consanguinity. The tentative gene loci identified for TH are assigned to chromosome band 7q36 and 8q24, but identification of the gene(s) responsible remains elusive [9]. Richieri- Costa et al., [15] reported on 37 patients belonging to different families who had the tibial hemimelia/split-hand/split-foot syndrome. These authors suggested that the maximum risk for an offspring of an affected person coupled with an unaffected person is 8.6% and that the maximum risk to a sibling of an isolated patient is 12.5%.


3. Conclusions

When lower extremity shortening is diagnosed prenatally, a detailed evaluation of fetal anatomy with the emphasis on the skeleton and long bones, hands and feet should be carried out.

Fetal movements in all joints and the amniotic fluid levels should also be checked. Sometimes it might be difficult to correctly distinguish between fibula and tibia prenatally (Table 1). The distinction can be achieved by checking the knee joint: the bone that directly articulates with the femur in the knee joint is the tibia. When congenital lower extremity shortening is diagnosed prenatally, proper counselling of the parents is mandatory in order for them to make a decision regarding termination or continuing the pregnancy. As this is a challenging task, counselling requires the input of geneticists and pediatric orthopedic surgeons.

Table 1. Differential diagnosis of prenatal features of fibular hemimelia and tibial hemimelia


Fibular hemimelia

Tibial hemimelia


20 per million

1 per million

Ultrasound findings

      shortening of the fibula

      anteromedial bowing of the tibia

      talipes equinovalgus

      absence of one or more of the lateral metatarsal rays

      80% unilateral, right

      shortening of the tibia

      intact fibula

      talipes equinovarus






-     Gollop-Wolfgang

-     Tibial agenesis-ectrodactyly


-     tibial hemimelia/split- hand/split-foot syndrome

-     Langer-Giedion



The Authors:

POP Lucian Gheorghe [1]

SUCIU Ioan Dumitru [1] [2]

TOADER Daniela Oana [1]

[1] National Institute of Mother and Child Care, Alessandrescu Rusescu, Bucharest (ROMANIA)

[2] Floreasca Emergency Hospital, Bucharest, (ROMANIA)


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