Posture disorders

Formation of proper spinal alignment

The process of establishing a habitual posture begins at birth. The primary role in this is played by the vertebral column and the sequential appearance of its physiological curves in the sagittal plane. The formation of these curves is inextricably linked with the child's motor development:

• Cervical lordosis. This is the very first physiological curvature. It appears when the infant begins to independently lift and hold the head while lying on the stomach. The maximum curve (apex of lordosis) is projected at the level of the C5–C6 vertebrae.
• Thoracic and sacral kyphosis. They develop as the child grows older, learning to sit and maintain trunk balance. The apex of the thoracic kyphosis is localized at the level of the Th6–Th7 vertebrae.
• Lumbar lordosis. It begins to form at the time of mastering an upright position — when the child learns to stand and walk. The apex of this curve is located at the level of the L4–L5 vertebrae.

Biomechanics and developmental factors

A person's ability to maintain a correct body position depends on the coordinated work of the musculoskeletal system. The entire apparatus is conventionally divided into two parts:

1. Passive component — the bone skeleton and ligamentous complex.
2. Active component — the muscular system.

The final body configuration is influenced by several biomechanical factors: the spatial position of the pelvis, the prominence of the spinal curves, muscle tone, and the position of the head relative to the trunk. The length and directional axes of the lower extremities, as well as the available range of motion in the joints, are also of great importance.

In addition, habitual posture is influenced by external and internal factors: occupational specifics, social and living conditions, daily lifestyle, and even the patient's current mental status.

Clinical markers of normal posture

Normality is characterized by a moderate degree of lordosis and kyphosis, as well as strict symmetry of both halves of the body. During a visual inspection of a standing patient, the following parameters are evaluated:

• Head and neck: the head is held straight, the forehead and chin lie in the same plane (strictly perpendicular to the floor), and the earlobes are on the same horizontal line.
• Shoulder girdle: the shoulders are slightly lowered and pulled back. The scapulae fit snugly against the chest wall, and their inferior angles are aligned along a single horizontal line.
• Spine and pelvis: the spinous processes of all vertebrae form an even vertical line. The line passing through the iliac crests is strictly horizontal.
• Soft tissues: the gluteal folds are at the same level. The waist triangles (the free space between the lowered arm and the waist contour) are completely symmetrical.
• Lower extremities: have the same length, and their axes are perpendicular to the support surface. The feet are parallel to the floor and slightly turned outward.

Pathological types and diagnostic principles

Any deviation from the clinical criteria listed above is regarded as a defect. Several main pathological types of the back are distinguished:

• Stooped back;
• Round back;
• Flat back;
• Kyphosis.

The basic method for identifying pathology is a visual inspection of the patient in an upright position. For an objective recording of the clinical picture in practical work, it is most appropriate to photograph the patient simultaneously in three projections: anterior, posterior, and lateral.

Associated structural pathologies: Spondylolisthesis

Sometimes the cause of severe spinal biomechanical disorders is spondylolisthesis — a pathological displacement of a vertebra relative to the one below it (most commonly relative to S1).

The degree of displacement is classified into four stages:

• Grade I — by 1/4 of the vertebral body surface;
• Grade II — by 1/2 of the surface;
• Grade III — by 3/4 of the surface;
• Grade IV — complete displacement across the entire surface.

Clinically, the condition may manifest as Thomas's sign: maximal flexion of one hip triggers reflexive flexion of the other leg. The absence of muscle relaxation on the side of the trunk tilt is also characteristic. For accurate diagnosis, radiography is mandatory (revealing the cause and degree of displacement), supplemented by MRI as indicated to assess neural compression.

Conservative treatment (limitation of vertical loads, bracing, positioning with flexed legs, massage, physical therapy, novocaine blocks, and NSAIDs) yields a lasting good result in only 6% of patients. Temporary improvement is observed in 63%. Most often, conservative measures serve as an auxiliary stage or preparation for surgical intervention: palliative (removal of the arch defect) or radical (spondylodesis — rigid fixation of the displaced vertebra).

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Scoliosis: etiology, pathogenesis, and differences from functional postural disorders.
• Surgical treatment of spondylolisthesis: indications for palliative surgery and spinal fusion techniques.
• Impact of psychoemotional status and lifestyle on the formation of back muscle tone.
• Radiological and MRI signs of neural compression in spinal deformities.
• Detailed assessment of waist triangles and lower limb axes in orthopedic practice.

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