(1)
Groningen, The Netherlands
Lower Leg Misalignment
Forwards and Outwards Lower Leg Bowing
Complaint: the parents come with their newborn child because the lower leg is bowed anteriorly and laterally.
Assessment: there is an anterolateral lower leg bowing (Fig. 11.1).
Fig. 11.1
Congenital anterolateral bowing of the left lower leg. (a) Left lower leg from in front and (b) viewed from the side
Differential diagnosis:
congenital anterolateral tibial and possibly fibular bowing
camp(t)omelia dysplasia (Cumming dysplasia syndrome)
congenital tibial pseudarthrosis
type I
type II
type III
type IV
type V
fibrous dysplasia of the tibia
Explanatory note: congenital anterolateral tibial and possibly fibular bowing. This is a rare deformity in which the tibia and possibly the fibula are bowed anterolaterally. On X-ray’s the cortex of the central part of the tibia is thickened particularly on the medial side. Therefore the bone marrow cavity is narrowed (Fig. 11.2). The deformity improves with time but never completely.
Fig. 11.2
(a) Anteroposterior and (b) lateral X-ray of a congenital anterolateral tibial bowing in a 4 weeks old child. On the anteroposterior X-ray the cortex in the central area of the tibia is thickened particularly on the medial side and the bone marrow cavity is narrowed. (c, d) Situation at 2½ years of age. A spontaneous improvement has occurred
Camp(t)omelic dysplasia1
The deformity is often described without the “t” (campomelic dysplasia). Both femurs and tibias with fibulas are bowed anterolaterally (Fig. 11.3). There are tibial cutaneous dimples and an equinous or clubfoot. Furthermore the patient is conspicuous because of a big head, low implanted ears, micrognathia and a small and flat face.
Fig. 11.3
Camp(t)omeliac dysplasia. Anteroposterior X-ray of both legs. Anterolateral bowing of both femurs and lower legs with equinus feet in a newborn child
Congenital tibial pseudarthrosis
There is an anterolateral tibial bowing at birth. Only in a small minority of cases there is already a pseudarthrosis at birth. However in the vast majority this occurs later on. The incidence is 1 in 200,000 births. Bilateral cases are even more exceptional. The cause is unknown. In three quarters of the cases we are dealing with a neurofibromatosis (Von Recklinghausen disease1). The periosteum is thickened and covered with a thick layer of soft tissue at the level of the pseudarthrosis. Five types can be classified (Fig. 11.4):
Fig. 11.4
Classification congenital tibial pseudarthrosis. Type I: simple. Type II: cystic. Type III: sclerotic. Type IV: dysplastic. Type V: dysplastic with pseudarthrosis of the fibula (Redrawn from: Staheli RT. Fundamentals of pediatric orthopaedics. 4th ed. Philadelphia/Baltimore/New York/London/Buenos Aires/Hongkong/Sydney/Tokyo: Lippincot Williams & Wilkins; 2008)
Type I. Simple congenital tibial pseudarthrosis: the lower leg is straight and at best slightly short. There is no narrowing in the diameter of the tibula and fibula on X-ray. After a minimal trauma a midshaft stress fracture of the tibia occurs which finally ends up in a pseudarthrosis (Fig. 11.5). This generally occurs after 5 years of age. The pseudarthrosis is often called the late type. A neurofibromatosis (Von Recklinghausen disease2) is not present.
Fig. 11.5
(a) Antroposterior and (b) Lateral X-ray of simple congenital tibial pseudarthrosis (type I) in a 10 year old boy
Type II. Cystic congenital tibial pseudarthrosis: in this type there is also no narrowing in the diameter of the tibia and fibula. Neurofibromatosis is not present. In the area of transition between the central and distal third of the tibia cystic abnormalities are present in the tibia and also occasionally in the fibula (Fig. 11.6). This appearance looks like a fibrous dysplasia. The lower leg is not bowed at birth. Angulation occurs during the first months after birth.
Fig. 11.6
(a) Anteroposterior and (b) Lateral X-ray of a cystic congenital tibial pseudarthrosis (type II) in a 2 month old child
Type III. Sclerotic congenital tibial pseudarthrosis: the pseudarthrosis occurs in a sclerotic segment. The bone marrow cavity is completely or partially obliterated. A stress fracture occurs in the cortex at the level of a sclerotic fragment which partially extends into the sclerotic bone (Fig. 11.7). There may be a neurofibromatosis in this type.
Fig. 11.7
(a) Anterolateral bowing of the left lower leg in a sclerotic congenital tibial pseudarthrosis (type III). (b) Anteroposterior X-ray and (c) Lateral X-ray of the left lower leg. Sclerotic congenital tibial pseudarthrosis which finally will ends up in a pseudarthrosis
Type IV. Dysplastic congenital tibial pseudarthrosis without fibular pseudarthrosis: in this case there is an intensification of the sclerosis with complete obliteration of the bone marrow cavity. The hourglass shaped tibia is bowed anteriorly and laterally (Fig. 11.8). The pseudarthrosis can be present at birth, but generally occurs after the child starts to walk. In this type a neurofibromatosis is almost always present.
Fig. 11.8
Dysplastic congenital tibial pseudarthrosis without fibular pseudarthrosis (type IV). (a) Anteroposterior and (b) Lateral X-ray of the right lower leg
Type V. Dysplastic congenital tibial and fibular pseudarthrosis. This is considered to be the most difficult type to treat. There is almost always a neurofibromatosis in these cases.
Fibrous dysplasia of the tibia
In fibrous dysplasia one or more fibrous tissue foci are found. There is a monostotic and a polyostotic type. The most common locations are in the ribs, tibia, femur and mandible. The abnormality is usually discoverd just before puberty (Fig. 11.9).
Supplementary assessment: anteroposterior and lateral X-rays of both legs.
Primary care treatment: none.
When to refer: if there is an anterolateral bowing of the leg or if there is a stress fracture present in a straight leg.
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