No one told you about the hips. Not the neonatologist. Not the early intervention team. Maybe your child’s PT mentioned it once, but it got lost in the sea of therapy goals and medical appointments. Now you are here because something hurts, or because someone finally ordered an X-ray, or because you read something that scared you. Here is what you need to know: hip displacement in cerebral palsy is common, it is progressive, and it is almost entirely preventable through surveillance. But only if someone is watching.
Why Hips Are at Risk in Children with CP
In a typically developing child, the ball of the femur (thigh bone) sits securely in the acetabulum (hip socket), held in place by balanced muscle forces. In a child with spastic cerebral palsy, the muscles around the hip are imbalanced: the adductors (inner thigh muscles) and hip flexors pull the femur inward and upward while the opposing muscles are too weak to resist. Over months and years, this unbalanced pull gradually draws the femoral head out of the socket.
This process is called hip subluxation (partial displacement) and, if unchecked, progresses to hip dislocation (complete displacement). A dislocated hip is painful, affects sitting, makes care difficult, and requires major reconstructive surgery.
What Is Hip Surveillance?
Hip surveillance is a systematic program of regular hip X-rays that tracks the position of the femoral head within the socket over time. The key measurement is the migration percentage (MP): the percentage of the femoral head that sits outside the edge of the acetabulum. An MP of 0% means fully contained; 100% means fully dislocated.
| Migration % | Status | Action |
|---|---|---|
| 0 to 30% | Normal to mild | Continue surveillance per schedule |
| 30 to 40% | At risk | Closer monitoring, Botox, bracing consideration |
| 40 to 50% | Significant subluxation | Surgical consultation recommended |
| 50%+ | Severe subluxation/dislocation | Surgical intervention typically needed |
If your child’s CP resulted from a birth injury, a case review can help fund the orthopedic monitoring they need.
The Surveillance Schedule
The Australian Hip Surveillance Guidelines (the most widely adopted protocol globally) recommend:
- GMFCS I-II (walkers): Baseline X-ray by age 2, then annually until age 7 to 10.
- GMFCS III-V (limited or non-ambulatory): Baseline by age 2, then every 6 to 12 months until skeletal maturity (age 14 to 16). These children are at highest risk.
If your child with CP has never had a hip X-ray, request one now. This is the single most important screening test in CP orthopedics, and many families are never told about it until displacement is advanced.
What Happens When Displacement Is Detected Early?
Early-stage displacement (MP 30 to 40%) can often be managed with conservative interventions: Botox injections to the hip adductor muscles, hip abduction bracing, and focused therapy to maintain range of motion. If displacement progresses despite these measures, soft tissue surgery (adductor release, psoas lengthening) can arrest progression while it is still mild.
Late-stage displacement (MP above 50%) typically requires reconstructive surgery: femoral osteotomy (reshaping the thigh bone) and/or pelvic osteotomy (reshaping the socket). These are major surgeries with significant recovery periods. The entire point of surveillance is to prevent reaching this stage.
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