Angular deformity

Lecture 4: Angular Deformities Around the Knee – Explained Like a Teacher

1. Definition of Angular Deformities

Angular deformities refer to abnormal bending or misalignment of the knee in different planes:

Sagittal plane (front-to-back misalignment): Leads to anterior or posterior angulation.

Frontal plane (side-to-side misalignment): Leads to valgus (knock-knees) or varus (bowlegs).

Complex deformities: Include a mix of these with rotational (twisting) or torsional issues.

2. Why Do Angular Deformities Matter?

They cause a shift in the mechanical axis of the leg, leading to:

Abnormal joint loading → Faster wear and tear → Early joint failure.

Social issues: Poor appearance (cosmesis), loss of self-esteem, and in extreme cases, depression or suicide.

3. Mechanical and Anatomical Axis of the Lower Limb

Mechanical axis: An imaginary straight line from the hip to the ankle, passing through the knee. If this line shifts, it leads to extra stress on certain parts of the knee.

4. Causes (Aetiology) of Angular Deformities

There are two main causes:

1. Physiologic (Normal Growth Patterns)

Newborns (0-1 year): Normal bowlegs (varus).

1-2 years: Legs straighten to neutral.

2-4 years: Knock-knees (valgus) develop.

By 9 years: Knees settle to a slight valgus (3-5° in boys, 3-7° in girls).

By 12 years: Should be completely resolved, but some may still have a mild deformity.

Treatment for Normal (Physiologic) Deformities:

Usually self-corrects with growth.

Watchful waiting and counseling to reassure parents.

2. Pathologic (Abnormal Causes)

Metabolic diseases: Rickets (due to Vitamin D or Calcium deficiency).

Trauma or infections: Damage to the growth plate (physis).

Tumors: Can disrupt normal bone growth.

Blount’s disease: A condition where the inner part of the knee grows abnormally, leading to bowlegs.Blount's disease is a condition that affects the growth of the tibia (shin bone), which creates a bend (bow) in the leg below the knee.Progressive varus deformity due to unequal growth of the medial physis of the proximal tibia

Skeletal dysplasia: Genetic bone disorders like achondroplasia.

5. Understanding Specific Causes

Blount’s Disease:

Affects the medial (inner) side of the tibia.

More common in overweight children.

The bone growth is unequal, causing progressive bowing of the legs.

Can happen in infants, children, or teenagers.

Recurrence is common even after treatment.

Rickets:

A metabolic bone disease due to Vitamin D or Calcium deficiency.

Bones become weak and cannot support body weight properly, leading to deformities.

Common signs:

Frontal bossing (prominent forehead).

Cupping at the wrist bones.

Rickety rosary beads (swelling at rib joints).

Treatment: Correcting Vitamin D/Calcium levels before considering surgery.

6. Treatment Options for Pathologic Angular Deformities

For Rickets: Nutritional correction; surgery only if the deformity persists.

For Growth Plate Injuries:

Early diagnosis leads to better outcomes.

Growth modulation (epiphyseal stapling or epiphysiodesis) to control bone growth.

Corrective osteotomy (bone cutting and realignment) if severe.

7. Surgical Treatment Options

Epiphyseal Stapling: Temporary growth control using small metal staples.

Epiphysiodesis: Permanent growth plate fusion to stop uneven growth.

Corrective Osteotomy: Cutting and realigning the bone.

Closing wedge osteotomy: Removes a wedge of bone to correct alignment.

Opening wedge osteotomy: Adds bone material to adjust the angle.

Complications:

Compartment syndrome (swelling cutting off circulation).

Nerve or blood vessel injury.

Non-union (bone fails to heal properly).

8. Modern Treatment: Ilizarov Technique

Gold standard for severe deformities.

Uses rings and pins to gradually correct deformity in multiple planes.

Can also lengthen the limb.

Best for complex and severe cases.

Conclusion

Some deformities (physiologic) resolve naturally.

Pathologic deformities need medical intervention.

Early treatment prevents complications.

Modern techniques like the Ilizarov method offer better correction.