Instrumental diagnostics of bone system pathologies
To accurately determine the nature of the deformity and plan treatment, a comprehensive approach to visualizing bone structures and soft tissues is used.
First and foremost, radiography is performed. Images must be taken in anteroposterior and lateral projections, and the examination zone must include adjacent joints—the hip and the knee. A special measuring grid is used to calculate the degree of shortening of the affected limb as accurately as possible.
Computed tomography (CT) allows for the detailing of anatomy: it helps physicians assess the spatial positioning of the femur (in the sagittal and horizontal planes) and study in detail how the proximal femur relates to the acetabulum.
Since delayed osteogenesis and developmental defects are often associated with vascular system dysplasia, methods for assessing blood flow and the functional state of tissues play an important role:
- Angiography shows the angioarchitecture of the arterial and venous bed, revealing the characteristics of regional blood circulation.
- Capillaroscopy, skin thermometry, and arterial oscillography are necessary for analyzing microcirculation, the degree of blood filling, and the general function of vessels in the affected segment.
- Electromyography is used to check the preservation of the functional activity of the limb's muscular system.
Fundamental principles and stages of treatment
The main rule in the orthopedics of congenital malformations is the earliest possible recognition of the problem (ideally right at birth) and the immediate initiation of therapy. The primary goal of medical intervention is to halt or at least partially slow down the progression of the deformity as the child grows. Any surgical intervention is considered strictly after the potential of conservative methods has been exhausted.
Conservative stage
Begins at an early age. The limbs are given a physiologically correct position using soft bandaging and special splints. If the pathology is accompanied by hip dislocation, Pavlik harness and Vylkovysky splint are used, supplemented by physical therapy and massage. This stimulates the proper formation of the acetabulum. By the time the child begins to walk, individual orthoses are selected. Walking is permitted strictly in a corrected position. This stage is critically important: it creates the foundation for future operations to be less traumatic and more effective.
Surgical stage
The surgical strategy implies a two-stage approach. First, anomalies of adjacent segments (above and below the defect) are eliminated to restore the weight-bearing function of the limb. Then, the length and integrity of the bone itself are restored.
Distraction methods using external fixation devices are used for bone lengthening. The rate of stretching (distraction) is kept very slow—from 0.75 to 1.0 mm per day. The process cannot be accelerated due to the poor extensibility of nerves and blood vessels, general underdevelopment of soft tissues, and delayed formation of new bone tissue. If femoral shortening does not exceed 4 centimeters, surgeons can use growth plate stimulation techniques by inserting bone allografts directly near them.
Leg shortening: clinical variants
Etiologically, leg shortening arises from intrauterine developmental pathology of the crural bones, which is localized in areas with underdeveloped or completely absent blood vessels. Patients suffer from lameness, gait disturbances, and foot and knee joint deformities. There are three main scenarios:
- Tibia aplasia (underdevelopment). Leg support is lost. In the complete form, a flexion contracture of the knee occurs, the joint itself is deformed, the patella is absent or underdeveloped, and movements are impossible. The foot is always underdeveloped, has an equinovarus deformity, and is in a state of internal dislocation.
- Fibula aplasia. Unlike the previous variant, support function is usually preserved, but it is accompanied by pronounced pelvic tilt and lameness. The knee joint is unstable, has a valgus deformity, and the patella is underdeveloped. The foot acquires an equino-planovalgus position. If aplasia is partial, the main symptom becomes the curvature of the leg axis.
- Shortening without gross anatomical defects. The problem is diagnosed late (at 6–18 years of age) because the leg length discrepancy increases slowly, reaching 3–7 cm. This leads to scoliosis and pelvic tilt. The range of motion in the joints is preserved. However, weakness of the lateral ligaments, valgus deviation, and patellar lateroposition (in 76% of cases) are frequently found in the knee. Planovalgus foot deformity is observed.
In treating such malformations, the majority of domestic specialists choose a complex but more effective limb-sparing strategy using compression-distraction devices, abandoning radical amputations and disarticulations followed by prosthetics, since one's own leg provides a better quality of life.
Briefly: answers to topical questions
What types of osteogenesis imperfecta are distinguished according to the Sillence classification?
The provided sources do not cite the Sillence classification, but they detail individual clinical variants of the disease. The following types of osteogenesis imperfecta are distinguished:
- Type I (Type I) — the mildest and most common form of the disease with fractures beginning in childhood.
- Type III (Type III) — a progressive deforming type characterized by fractures at birth and pronounced deformities.
- Type IV (Type IV) — a moderately severe type with pronounced osteopenia and bone deformities.
- Type V – XI — other types of the disease.
Mutations in which genes are the main cause of osteogenesis imperfecta development?
According to the sources, osteogenesis imperfecta is caused by mutations in genes encoding type I collagen α1 and α2 molecules. Mutations in the CRTAP gene are described in certain recessive forms.
What specific radiological signs are characteristic of osteogenesis imperfecta?
Osteogenesis imperfecta is characterized by a number of specific radiological signs reflecting pronounced bone fragility and pathology:
- Wormian bones (Wormian bones) — identification of intrasutural or Wormian bones on skull radiographs.
- Popcorn symptom (popcorn calcification) — characteristic calcification of epiphyses containing islands of calcified cartilage.
- Bowing deformity (bowing deformity) — pronounced curvature of long tubular bones due to multiple fractures.
- Density changes — a general decrease in bone tissue density and thinning of long tubular bones.
What extraskeletal manifestations are characteristic of patients with osteogenesis imperfecta?
The type III osteogenesis imperfecta described in the sources is characterized by blue sclerae at birth followed by their whitening in adulthood, progressive hearing loss, and malocclusion.
Class and exam questions
Why is bone distraction performed so slowly (up to 1 mm per day)?
The slow rate is due to the low elasticity and extensibility of neurovascular bundles, underdevelopment of surrounding soft tissues, and slow formation of new bone against the background of vascular dysplasia.
Is it possible to proceed directly to surgical limb lengthening in congenital defects?
No, surgical intervention is used strictly after a full course of conservative treatment (splinting, bracing, physical therapy), which prepares the tissues and makes the surgery less invasive.
Is the weight-bearing capacity of the leg preserved in tibial aplasia?
As a rule, weight-bearing capacity is completely absent. This is accompanied by severe flexion contracture of the knee joint and internal dislocation of the underdeveloped foot.
What else to study on this topic
- Specifics of using Pavlik harness and Wilensky splint in concomitant hip dislocation.
- Biomechanics of compression-distraction osteosynthesis using external fixation devices.
- Congenital multiple arthrogryposis: pathogenesis of joint contractures.
- Surgical technique for stimulating growth plates with allografts in femoral shortening up to 4 cm.
- Psychosocial rehabilitation of patients with severe congenital musculoskeletal deformities.
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