What is a realistic expectation for walking in a child who undergoes hip dysplasia surgery before 18 months, and is sitting in a split position after cast removal a concern?

Walking Timeline After Hip Dysplasia Surgery Before 18 Months

Children who undergo hip dysplasia surgery before 18 months typically begin walking 3-6 months after cast removal, though this timeline varies based on the surgical procedure performed and the child's age at surgery. 1

Expected Walking Timeline by Surgical Approach

For Closed Reduction (Under 12 Months)

• Children under 12 months who undergo closed reduction and spica casting typically start walking closer to the earlier end of the timeline 1
• The spica cast is usually worn for 3 months, followed by orthosis fixation 2
• Most children begin ambulating within 3-4 months after cast removal, as their motor development was less established before immobilization

For Open Reduction (12-18 Months)

• Children aged 12-18 months who require open reduction (with or without femoral shortening) face a longer recovery 1
• These children were often already walking or close to walking before surgery, so they must relearn ambulation after prolonged immobilization
• Walking typically resumes 4-6 months after cast removal 1, 2
• Additional procedures like femoral osteotomy may extend this timeline slightly

The Split-Sitting Position After Cast Removal

Split-sitting (W-sitting) after cast removal is common and generally not concerning in the immediate post-operative period, but should gradually resolve within 3-6 months as the child regains normal hip mobility and muscle strength.

Why Split-Sitting Occurs

• Prolonged immobilization in the spica cast causes hip abductor and extensor muscle weakness 2
• The child develops compensatory movement patterns during the casting period
• Hip capsule tightness and altered proprioception contribute to this positioning preference 1

When to Be Concerned

• Persistent split-sitting beyond 6 months post-cast removal warrants evaluation for residual hip instability or inadequate reduction 3
• If accompanied by limited hip abduction, asymmetric leg length, or refusal to bear weight, earlier reassessment is needed 4, 5
• Physical therapy should be initiated if the child shows no improvement in sitting posture by 3 months post-cast removal 2

Monitoring for Complications

Critical Follow-Up Assessments

• Serial physical examinations should continue at all well-child visits through age 5 6
• Follow-up radiographs at age 1 and 4 years assess acetabular development and detect avascular necrosis (AVN) 6
• AVN occurs in approximately 13% of cases and is associated with severity of initial dislocation 3

Red Flags Requiring Urgent Evaluation

• Persistent limping or refusal to bear weight beyond 6 months post-surgery 3
• Progressive leg length discrepancy 5
• Decreasing hip abduction range of motion 4, 5
• Pain with hip movement (uncommon in young children but concerning for AVN) 3

Factors Affecting Walking Timeline

Age-Related Considerations

• Younger children (under 12 months) adapt more quickly to post-operative changes 1
• Children aged 12-18 months require more time to regain pre-operative motor skills 1, 2
• The closer to 18 months at surgery, the longer the expected recovery period for independent ambulation 1

Surgical Complexity Impact

• Simple closed reduction: 3-4 months to walking 1
• Open reduction alone: 4-5 months to walking 1
• Open reduction with femoral shortening: 5-6 months to walking 1, 3
• Approximately one-third of patients require secondary surgical procedures within 4 years, which would reset the walking timeline 3

Prognostic Indicators

• Higher baseline acetabular index correlates with longer recovery and higher reoperation rates 2
• Bilateral hip involvement extends the walking timeline compared to unilateral cases 3
• Children who receive acetabular osteotomy at the time of open reduction (when over 18 months) have better long-term outcomes but similar initial walking timelines 3