Coxa Vara, Sacral agenesis

Question 1

What is developmental coxa vara?

Answer 1

• A decrease in neck-shaft angle (^o)that is associated with an ossification defect in inferior femoral neck

Question 2

What is the epidemiology of congential coxa vara?

Answer 2

• 1 in 25,000 births in US
• males = females
• generally presents between age of ambulation and 6 years
• Bilateral in 1 in 3 cases
• Genetics- no clear inheritane pattern, likely Autosomal dominant
• risk factors
  
  • congential defects
  • acquired conditions that -> fatigue failure with physiological stress of weight bearing
    
    • trauma
    • SCFE
    • Legg-Calve-Perthes

Question 3

What is the pathophysiology of congential coxa vara?

Answer 3

• Abnormal development of proximal femoral cartilagenous physis or ossification centre which causes
  
  • decreased proximal femoral neck- shaft angle
  • vertical position of proximal femoral physis and varus
  • biomechanically
    
    • coxa vara and vertical physis increases
      
      • physeal sheering forces
      • inferior medial neck compression forces

Question 4

What are the associated conditions of Coxa Vara?

Answer 4

• Femoral neck stress fx
• Decreased limb length
• early hip OA

Question 5

What are the Symptoms and signs of congential coxa vara?

Answer 5

Hx include

• Previous hip trauma/ infection
• assoc skeletal abnormalities
• prenatal development history
• effect on their activities
• FHX

Symptoms

• Gait abnormality
  
  • painless wadding Trendelenberg gait when bilat
  • due to abductor weakness from tension abnormality
  • Painless limb when unilateral
• LLD
• excessive lumbar lordosis

​Signs

• High riding greater trochanter
• limb shortening
• restricted HIP rom in all planes that is usually non tender
• Trendelenberg gait

Question 6

what imaging is useful in dx of congential coxa vara

Answer 6

• Xrays
  
  • AP hip with limb internally rotated & Lateral hip
  • See
    
    • Neck shaft angle <125o
    • increased Hilgenreiner’s epiphyseal angle ( Normal <25 0)
    • triangulat metaphsyeal fragment in inferior femoral neck- looks like an inverted Y radiolucent
    • decreased femoral anterversion
• CT
  
  • delinate femoral defects
  • oreintation of deformity

Question 7

What are the aetiologies of coxa vara?

Answer 7

• Congential
• Acquired
• Dysplasia
• Developmental
• Cretinism

Question 8

What is the tx of coxa vara?

Answer 8

Non operative

• Observation alone
  
  • for Hilgenreiner’s physeal angle <45
  • most will correct spontaneously without surgery

Operative

• Corrective valgus derotational osteotomy
  
  • Hilgenreiner’s physeal angle >60
  • or 45-60 with assoc limp/progession of varus

Question 9

What are the goals and apporach to valgus derotational osteotomy?

Answer 9

• Correct neck shaft angle
• correct limb length discrepancy
• correct hip anteversion/retroversion
• reestablish abductor muscle tensioning

Approach

• lateral approach to hip
• protect periosteum and physis
• sub-troachanteric valgus producing osteotomy
• attention to limb length discrepancy
• May need transfer of GT to properly tension the abductor muscles
• Hip spica for 6 weeks

Question 10

What are the complications of congential coxa vara?

Answer 10

• Loss of correction
• premature closure of proximal femoral physis
• Overgrowth of proximal femur
• dysplasia of acetabulum

Question 11

What is sacral agenesis?

Answer 11

• Condition of partial or complete absence of sacrum and lower lumbar spine
• highly associated with Maternal Diabetes

Question 12

What is sacral agenesis associated with?

Answer 12

• Gastrointestinal disorders- imperforated anus
• genitourinary disorders
• cardiovascular disorders
• lower extremity deformities
• progressive kyphosis

Neurological injury

• motor deficit corresponds to level
• protective senstion is usally intact
  
  • ​lesser rate of decubitus ulcers
  • dx from myelodysplasia

Question 13

What is seen on physical exam of a child with sacral agenesis?

Answer 13

• Prominent lower lumbar spine
• extended knees, flexed hips, and equinovarus feet
• classic sign of Buttock Dimpling

Question 14

What is the tx of sacral agenesis?

Answer 14

• Spinal stabilisation proceedures
  
  • Otherwise progressive kyphosis will develop between spine and pelvis
  • kyphosis progresses to the point that the child must use their hands to support the trunk , therefore unable to use their hands for other activities