Orthopedics - Oleksa A.P. 2006

Pathophysiology of Joints
Developmental Defects and Congenital Skeletal Anomalies
Dyschondrosteosis

Dyschondrosteosis is a form of dwarfism characterized by short stature and limb shortening primarily affecting the forearms and lower legs. The condition was first described in 1929 by Leri and Weil.

Dyschondrosteosis predominantly affects females. The condition is usually apparent at birth due to noticeable shortening of the middle segments of the limbs. In some cases, the shortening becomes more evident later in childhood during periods of rapid growth, when the manifestations grow more pronounced.

The Etiology of dyschondrosteosis remains unclear. Both familial recessive and dominant inheritance patterns of the disease have been reported.

The Pathophysiology involves disorders of enchondral ossification, leading to shortening of the BONES OF THE forearm and lower leg, though the precise reason for this specific localization is unknown. Because this condition is extremely rare, There is a lack of sufficient clinical observations for its more thorough study.

Clinical Features of the disease. First, children with dyschondrosteosis are short-statured and experience slowed growth, and adults typically do not exceed 135-140 cm in height. In contrast to Achondroplasia, the Skull, face, and trunk develop normally.

Shortening of the upper extremities is caused by pathological Changes in the forearms. The radii are deformed in the frontal plane (varus), while the ulnae are deformed in the sagittal plane. Consequently, the deformity at the wrist joint resembles Madelung's deformity. Similarly, the ulnar HEAD protrudes dorsally; however, upon maximum passive supination—which is significantly restricted—and by applying pressure to the radius, it reduces into the radioulnar joint before slipping out of place again. Extension of the hand at the wrist joint is also restricted.

The lower extremities are likewise shortened due to anatomical shortening and varus bowing of the bones of the lower leg. Hypoplasia or Aplasia of the Fibula may occasionally be observed.

Radiological examinations of the skull, spine, and the proximal and distal segments of the limbs generally reveal no abnormalities, except for occasional Developmental anomalies of the proximal end of the humerus or Femur. However, significant pathological changes are evident in the bones of the forearm and lower leg.

The radius exhibits a bowed varus deformity, and its head is deformed and thickened. The distal articular end is also skewed and tilted toward the ulnar side. The ulna is deformed in the sagittal plane, with its head presenting a dorsal subluxation. Consequently, the proximal row of Carpal Bones forms a sharper arch and lies between the somewhat displaced ends of the forearm bones. The bones of both hands are normally developed.

Less pronounced deformations are found in the bones of the lower leg. The Tibia is anatomically shorter and varus-deformed. The fibula is also deformed, and its hypoplasia or aplasia is occasionally detected.

When distinct clinical and radiological features are present, the Diagnosis of dyschondrosteosis is straightforward. However, atypical cases with milder mesomelic dwarfism can make diagnosis more challenging.

Treatment. Upon diagnosing dyschondrosteosis, children are prescribed comprehensive conservative treatment to prevent the progression of the deformity. This includes Muscle massage, passive and active range-of-motion exercises for the JOINTS OF THE affected limbs, vitamin therapy, and A balanced diet.

Bone growth has also been stimulated by irritating the growth plate through the insertion of bone pegs, though this supportive method has not gained widespread acceptance.

In adolescents and adults with pronounced bone curvatures, corrective osteotomies are performed. To lengthen limb segments, the Ilizarov method can be employed—performing osteotomies within the apparatus followed (after 6 days) by gradual distraction of the bone fragments (0.25 mm four times a day).

The efficacy of this method has been confirmed in numerous patients with other congenital and acquired shortenings of limb segments, particularly the lower extremities. The remodeling of the distraction regenerate proceeds normally until full-fledged mature Bone tissue is formed. Clinical observations by Andrianov V.L., Sadofyev V.I., Mischenko Yu.I., et al. (1986) demonstrated that regenerate remodeling in children occurs significantly faster when a subperiosteal demineralized bone graft is implanted during the osteotomy.