(1)
Groningen, The Netherlands
One Leg is Shorter or Longer than the Other
One Leg is Shorter than the Other
Complaint: the parents notice that one of the child’s legs is shorter than the other or they find that the child has an abnormal gait (Fig. 15.1).
Assessment: on examination leg length difference can be measured with the help of a method using planks.
Differential diagnosis:
congenital
idiopathic hemihypotrophy (hemihypoplasia)
Russell-Silver syndrome
congenital deficiency
developmental dysplasia of the hip
talipes equinovarus (pes equinovarus, clubfoot)
vascular
Legg-Calvé-Perthes disease
(Perthes disease, coxa plana, Waldenström disease)
ischemic necrosis of the femoral head
neurological
spastic hemiplegia
poliomyelitis
peripheral nerve or plexus injury
plexus injury
growth plate damage
acute osteomyelitis
septic arthritis of the hip
growth plate fracture
slipped capital femoral epiphysis
radiotherapy
bone tumor
unicameral bone cyst (juvenile-, solitary-, simple bone cyst)
osteochondroma (exostosis)
enchondroma
Ollier disease
Mafucci syndrome
Explanatory note: congenital
Fig. 15.1
Measurement of leg length difference using the plank technique. (a) The anterior superior iliac spines are palpated with the thumbs. If the thumbs are not at the same height there is a leg length difference. (b) If there is a leg length difference, then planks with various thicknesses are placed under the foot on the shorter side, until the anterior superior iliac spines are at the same level. The thickness of the planks is the measurement of the shortening. (c) Leg length difference in the thighs can be shown with the child lying on its back with the legs and knees flexed to 90°. If there is a difference in knee height there is a leg length difference in the thighs as in this case (the same patient as in (a). (d) By allowing the patient to lie supine with the knees flexed to 90° one can see if there is a leg length difference in the lower legs. If the soles of the feet are at the same height as in this case, there is only a difference in the length of the upper legs (the same patient as in (a)
Idiopathic hemihypotrophy
Hemihypotrophy isusually idiopathic but can also be part of the Russell-Silver syndrome. 1 Idiopathic hemihypotrophy can involve not only a complete body half but may involve just one extremity. We are dealing with hemihypotrophy if the short leg is thinner and does not fit in with the rest of the body. Hemihypotrophy occurs in 1 in 100,000 individuals. Apart from the difference in leg length other abnormalities may be present such as palate anomalies, cleft lip and palate, urogenital anomalies and mental retardation. The final difference in leg length is generally not more than 2 cm.
Congenital deficiency
In this case the whole lower extremity is missing or parts of it and in the latter case there is usually a severe difference in leg length (Fig. 15.2).
Fig. 15.2
Congenital deficiency: in this case a proximal focal femur deficiency on the right side
Developmental dysplasia of the hip
An untreated unilateral hip dislocation will lead finally to a leg length difference of 5–6 cm (Fig. 15.3).
Fig. 15.3
Leg length difference of 2 cm in the left thigh as a result of a developmental dysplasia with a dislocated left hip. The leg length difference can increase in adulthood up to 5 or 6 cm
Talipes equinovarus
A talipes equinovarus usually causes a leg length difference of less than 1 cm.
Vascular
Legg-calvé-perthes disease
Perthes disease generally causes a leg length difference of not more than 1 cm.
Ischemic necrosis of the femoral head
This can be a complication of a fracture in the proximal part of the femur. In children the chance of an ischemic necrosis of the femoral head is 75 % after a transepiphyseal fracture, a transcervical and a cervico trochanteric fracture and 15 % after an intertrochanteric fracture. Ischemic necrosis of the femoral head causes damage to the proximal femoral epiphysis causing a growth disorder. The final leg length difference is dependent on the age at which this complication occurred.
Neurological
Spastic hemiplegia
In this case the leg length differences are seldom more than 1.5 cm (Fig. 15.4).
Fig. 15.4
Right spastic hemiplegia. There will be a maximal leg length difference of 1.5 cm in the involved leg when the child has stopped growing. The leg length difference will be compensated by plantar flexion in the ankle
Poliomyelitis
Leg length differences caused by poliomyelitis are not often seen in better developed countries.
Peripheral nerve or plexus injury
Hemihypotrophy can occur as a result of a nerve injury or plexus injury.
Growth Plate Damage
Acute osteomyelitis
In some cases an acute osteomyelitis can cause a destruction of the growth plate (see Chap. 18). This can lead to substantial growth inhibition. Sometimes the growth plate partially closes and apart from shortening also causes a progressive deformity (Fig. 15.5).
Fig. 15.5
(a–b) Situation after a meningococcal sepsis in a newborn child with damage to diverse growth plates in the right knee with serious positional deformities and shortening of the right leg as a result. (c) A right knee arthrodesis was carried out because of a serious progressive deformity of the joint. (d) After the right knee arthrodesis an extensive leg length difference remains, which in the first instance was dealt with a sole elevation. In order to prevent ankle instability a long leg splint was mounted onto the shoe. Later on a leg lengthening procedure was carried out (see Fig. 15.15). Operation performed in the early eighties
Septic arthritis of the hip
A septic arthritis of the hip that has been treated too late can lead to destruction and ischemic necrosis of the femoral head. This can lead to a leg length difference of up to 4 or 5 cm, depending on the age of the patient at the time of the infection.
Growth plate fracture
In 1 % of growth plate fractures damage in the growth plate causes a bony connection between the metaphysis and the epiphysis. A shortening will only occur if this bony connection is located centrally. Apart from shortening a misalignment will occur if the bony connection is asymmetrical. The leg length difference that occurs is dependent on the age of the child and the localization of the fracture. The final leg length difference will be greater the younger the child is. Growth plate closure above or under the knee will lead to a greater leg length difference than growth plate closure in the epiphysis in the proximal part of the femur or in the distal part of the tibia.
Slipped capital femoral epiphysis
A slipped capital femoral epiphysis seldom leads to a leg length difference of 2 cm or more (see Chap. 9).
Radiotherapy
Radiotherapy for the treatment of tumors may lead to damage to the growth plate.
Bone Tumor
Unicameral bone cyst, osteochondroma and enchondroma
Bone tumors can inhibit growth. Examples of growth inhibition are in solitary bone cysts, osteochondromata and enchondromas. Enchondromas may be part of Ollier disease2 (Fig. 15.6) or the Mafucci syndrome2. The difference between Ollier disease and the Mafucci syndrome2 is that in the latter subcutaneous hemangiomas are present.
Fig. 15.6
Ollier disease. (a) Positional deformity and shortening of the right leg. (b–c) Multiple enchondromas in several metaphyses of the right femur and tibia
For supplementary assessment, primary care treatment, when to refer, secondary care treatment, if one leg is longer than the other, see too long leg, pp. 325 and 331 in this chapter.
One Leg is Longer than the Other
Complaint: the parents feel that the child has a leg length difference or they find that the child walks abnormally.
Assessment: the leg length difference can be measured using the plank method.
Differential diagnosis:
congenital
idiopathic hemihypertrophy (hemihyperplasia)
Beckwith-Wiedemann syndrome
Proteus syndrome
vascular
arteriovenous fistulas
Klippel-Trenaunay-Weber syndrome
neurological
