Congenital limb hypoplasia

Definition

Congenital anomalies (hypoplasia) of the limbs are a group of malformations that include abnormalities of the hip, thigh, knee, lower leg, ankle, and foot. There may be a complete absence of a limb or any of its parts, underdevelopment of an entire segment or one of the bones that make up that segment, underdevelopment of muscles, vessels and nerves, connective tissue ties, etc. A combination of several congenital anomalies is possible. Diagnosis is based on examination data, radiography, CT, MRI, and other studies. Treatment is usually surgical. The prognosis depends on the severity of the pathology.

General information

Developmental malformations of the lower extremities are a large group of anomalies that occur in the fetal period and vary considerably in severity. In orthopedics and traumatology, they are relatively common and account for 55% of the total number of congenital anomalies in the musculoskeletal system. Gross malformations are diagnosed immediately after birth. In some cases, minor anomalies may be asymptomatic or almost asymptomatic and may become an incidental finding during examination for other injuries and diseases. Pediatric orthopedists and traumatologists treat congenital anomalies of the lower extremities.

Reasons

Developmental anomalies can result from mutations, as well as external and internal teratogenic factors. The most common external factors that negatively impact limb formation are infectious diseases, nutritional disorders, medications, and radiation exposure. Internal factors that can lead to impaired limb formation include advanced maternal age, uterine pathology, severe somatic diseases, some gynecologic diseases, and endocrine disorders.

Classification

Malformations that result from deficient formation:

• Amelia – a limb is completely missing. Sympus apus (both lower limbs missing) and sympus monopus (one lower limb missing) are possible.
• Phocomelia: The limb’s middle and/or proximal parts and the corresponding joints are missing. It may be bilateral or unilateral. Sometimes, all limbs, both lower and upper limbs, are involved. Complete phocomelia: The tibia and femur are absent, and the formed foot is attached to the trunk. Distal phocomelia: The tibia is absent, and the foot attaches to the femur. Proximal phocomelia: The femur is absent, and the tibia and foot are attached to the trunk.
• Peromelia is a type of phocomelia in which a part of the limb is missing in combination with the underdevelopment of its distal part (foot). Complete peromelia—the leg is missing, with a skin protrusion or a rudimentary toe in the place of its attachment. Incomplete peromelia —the femur is absent or underdeveloped, and the limb also ends with a skin protrusion or a rudimentary toe.

In addition, a distinction is made between the absence (aplasia) of the fibula or tibia, the absence of phalanges (aphalangia), the absence of toes (adactyly), the presence of a single toe (monodactyly), as well as typical and atypical forms of the split foot due to the absence or underdevelopment of its middle parts.

Malformations that result from insufficient differentiation:

Sirenomelia is a fusion of the lower extremities. There may be a fusion of only soft tissues or a fusion of both soft tissues and some tubular bones. It is often combined with the absence or underdevelopment of pelvic and limb bones. In sirenomelia, both the absence of feet and the presence of one or two feet (more often rudimentary) may exist. Usually, there is simultaneous underdevelopment of the rectum, anus, urinary system, and internal and external genitalia.

In addition, the group of malformations due to insufficient differentiation includes synostosis (bone fusion), congenital hip dislocation, congenital clubfoot, arthrogryposis, and some other anomalies.

Malformations due to increased number: increased number of lower limbs – polymelia, doubling of the foot – diplopodium.

Malformations due to insufficient growth – hypoplasia of various bones of the lower limbs.

Malformations due to overgrowth – gigantism occurs when a developed limb is unilaterally enlarged.

Congenital constrictions are tissue pulls occurring at various locations on a limb, often impairing limb function.

Types of anomalies

Underdevelopment of the femur

It accounts for 1.2% of the total number of congenital skeletal deformities. They are often combined with other anomalies, including aplasia of the fibula and the absence of the patella. Manifested by lameness. The degree of limb dysfunction depends on the amount of shortening and the severity of the malformation. When the diaphysis is affected, the adjacent joints, as a rule, are not changed; their function is preserved in full. When the distal femur is affected, contractures usually occur. The limb is rotated and shortened. The pelvis is skewed and lowered to the side of the defect. The gluteal fold is flattened or absent. The buttock and thigh muscles are atrophied, and the foot is in an equinus position. Radiography of the femur shows shortening and underdevelopment of the segment.

Treatment is surgical and aimed at restoring limb length. At an early age, surgeries are performed to stimulate the growth zones. From the age of 4-5, osteotomy is performed in combination with a distraction apparatus. Suppose the shortening is so significant that limb length restoration is not possible. In that case, foot amputation is necessary, sometimes in combination with knee arthrodesis (to create a long functional residual limb). Special shoes and various orthopedic devices can be used if the shortening is insignificant.

Congenital hip dislocation and hip dysplasia

Congenital dislocation of the hip is relatively rare, and various degrees of dysplasia are usually found. Pathology is usually unilateral. Girls suffer seven times more often than boys. In 5% of cases, direct hereditary transmission of the malformation is detected. It is manifested by lameness, rotation, and shortening of the limb. With a bilateral anomaly, a duck’s gait occurs. Radiographs of the hip joint show a reduction and flattening of the head and its standing above the acetabulum. Treatment at an early age is conservative, with the use of various devices, such as special panties and pads. Surgery is performed after 2-3 years of age in case of intractable dislocations.

Valgus and varus deformity of the hip

It develops due to ossification disorder of the neck or intrauterine damage to the cartilage; it is equally common in girls and boys; in 30%, it is detected on both sides. Valgus deformity is usually asymptomatic. Varus curvature is accompanied by lameness, limitation of movement, and rapid fatigue of the limb. Clinical manifestations resemble congenital dislocation of the hip. Radiography determines delayed head ossification, shortening, and thinning of the femur. The neck-diaphyseal angle is reduced. Treatment is surgical; corrective osteotomy is performed to increase the neck-diaphyseal angle.

Congenital dislocation of the patella.

It’s quite rare. There is a hereditary predisposition. It can be combined with other malformations; boys are twice as often affected as girls. Congenital dislocation of the patella is manifested by rapid fatigue of the limb, unsteady gait, and frequent falls. Contracture is possible. Without treatment, the problem worsens with age, deforming arthrosis occurs, and valgus curvature of the limb develops. Radiography of the knee joint shows underdevelopment and displacement of the patella (more often to the outside) and underdevelopment of the external condyle. Treatment is surgical – the patellar collateral ligament is moved and fixed in the medial position.

Absence of the patella

It is often combined with other anomalies of the knee joint (underdevelopment of the articular ends of the tibia and femur), dislocation of the femur and tibia, clubfoot, and other malformations. The course of isolated pathology is usually asymptomatic, but increased loads, weakness, and fatigue of the limb are possible. In the case of an isolated anomaly, no treatment is required.

Congenital tibial dislocation

It is rare and is usually bilateral. It is accompanied by contracture and deformity of the knee. The type of deformity depends on the type of displacement of the tibia bones. The muscles of the thigh and tibia are underdeveloped and often have abnormal attachment points. Pathology is often combined with ankle joint anomalies and the tibia’s absence or underdevelopment. Treatment at an early age is conservative (traction followed by repositioning). At two years and older, surgery is performed – open reduction of the dislocation, if necessary, in combination with correction of concomitant skeletal pathology.

Valgus and varus deformities of the knee joint

They are rare, may be inherited, and are usually combined with femoral neck deformity and flat feet. They also cause early severe gonarthrosis. At the age of up to 5-6 years, correction is carried out using conservative methods, followed by surgical intervention. Depending on the severity of the pathology, an isolated osteotomy is performed in the area of the femoral epicondyles, or femoral osteotomy is combined with grooved, wedge, or transverse osteotomy of the tibia.

Aplasia or underdevelopment of the tibia

It is accompanied by shortening and curvature of the limb. The foot is supinated, in an equinus or subluxation position. Support is impaired. It may be combined with underdevelopment or absence of the foot bones, underdevelopment or dislocation of the patella, atrophy, and impaired development of the lower leg and thigh muscles. Children up to 3 years of age receive conservative therapy to restore the normal position of the foot. Subsequently, tibial lengthening is performed using distraction devices.

False tibial joint

It may be true or arise at the site of a congenital cyst. Pathologic mobility, angular or arched curvature in the area of the false joint, muscle atrophy, thickening and scarring of the skin, and shortening, and thinning of the limb are detected. Radiographs of the tibia bones show osteoporosis. Treatment is surgical with bone grafts or Ilizarov apparatus.

All these treatment options are available in more than 100 hospitals worldwide (https://doctor.global/results/diseases/congenital-limb-hypoplasia). For example, Bone lengthening can be done in 14 clinics across Turkey for an approximate price of $4.7 K (https://doctor.global/results/asia/turkey/all-cities/all-specializations/procedures/bone-lengthening).