Journal of Pediatric Orthopaedics - 2026-08-01 - Journal Article; Systematic Review
Variety is Not the Spice of Life: Inconsistent Definitions of Failure After Hip Reconstruction in Cerebral Palsy.
VanderHoek EN, Tarkunde Y, Bauer JP, Zusman NL
Topics
Key Takeaway
Failure rates after bony hip reconstruction in CP range from 1.8% to 74% across 27 studies due to inconsistent definitions, with Reimer Migration Percentage (63%) and revision surgery (48%) being the most commonly used but non-interchangeable endpoints.
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Summary
This PRISMA-compliant systematic review of 630 screened abstracts (27 included) examined how 'failure' is defined after bony hip reconstruction in CP patients and compiled reported failure rates. Reimer Migration Percentage thresholds were used in 63% of studies and revision surgery in 48%, with additional definitions including arthritis/pain (18.5%) and lateral center edge angle (18.5%). The 40-fold range in failure rates (1.8%–74%) directly reflects definitional inconsistency rather than true outcome differences, precluding meta-analysis.
Key Limitation
Overlapping patient cohorts from two institutions contributing six publications introduce the risk of duplicate patient counting, which could distort pooled failure rate estimates even without formal meta-analysis.
Original Abstract
BACKGROUND
Hip displacement (subluxation or dislocation) is common in children with cerebral palsy (CP), especially those who are nonambulatory. If unaddressed, this can cause pain, stiffness, hygiene difficulties, and seating imbalance. Progressive hip subluxation or dislocation often requires surgery, and further displacement after reconstruction may be described as "failure." There is currently no standardized definition of failure after the index procedure. This review aimed to identify published failure definitions and compile reported failure rates after index bony hip reconstruction.
MATERIALS AND METHODS
Following PRISMA guidelines, a systematic review was performed using PubMed, SCOPUS, and OVID databases (1990 to 2023). Exclusion criteria included soft tissue-only procedures, gait analysis-based outcomes, adults, non-CP syndromes, salvage or arthroplasty procedures, nonoperative management, unavailable full-text, non-English articles, novel techniques, radiographic or morphologic studies, or procedures without osteotomy. Studies without a definition of "failure" were excluded. Abstract review, full-text screening, and data extraction were performed by 2 authors, with a third adjudicating disagreements. Patient demographics, failure definitions and rates, and study quality were collected. Bias was assessed, and data were considered for pooled analysis.
RESULTS
Of 630 abstracts, 27 studies were included. Failure rates ranged from 1.8% to 74% (mean 26.3%±17.4%). Definitions varied: Reimer Migration Percentage (MP) (63%) and revision surgery (48%) were most common. Other definitions included arthritis/hip pain (18.5%) and lateral center edge angle (18.5%). Significant heterogeneity in definitions, inclusion criteria, and follow-up, plus overlapping patient cohorts, precluded meta-analysis. The lowest rate (1.8%) reflected a single revision for painful instability. The highest (74%) came from a study defining failure as reoperation without MP. Two institutions contributed 6 publications.
CONCLUSIONS
There is no consistent definition of failure after bony hip reconstruction in CP, impeding comparison of techniques and outcomes. Children with CP are medically complex, and revision surgeries have significant implications. We advocate for a more uniform definition of failure following hip reconstruction in children with CP.
LEVEL OF EVIDENCE
Level III-systematic review of studies.