The geometry of slipped capital femoral epiphysis: Implications for movement, impingement, and corrective osteotomy

George T Rab

Research output: Contribution to journalArticlepeer-review

172 Scopus citations


Metaphyseal impingement limits motion in high-grade slipped capital femoral epiphysis (SCFE). A three-dimensional volume/surface computer model was used to study the geometry of impingement, which may take the form of impaction, which causes levering or requires compensatory alteration in motion, or inclusion that occurs after remodeling and may lead to acetabular cartilage damage. The majority of deformities seen clinically can be reproduced with posterior epiphyseal displacement in the plane of the physis. By using the 3-D movements of normal walking, this model predicts little anterior metaphyseal impingement in the normal hip: As posterior slip angle increases to 25°, minor impingement can be eliminated with as little as 20°of external rotation. High-grade posterior slips (75°) require external rotation of 50-60°during walking to minimize impaction. Sitting increases impingement for all slip geometries, requiring proportionately greater external rotation. As remodeling restores a more normal arc of motion, an increasing proportion of the femoral head is composed of the remodeled, included metaphyseal prominence. This study explores the potential role of contact between the acetabulum and the metaphysis in the production of abnormal range of motion after SCFE, and simulation estimates the correction needed by osteotomy to allow normal walking and sitting. The inclusion of significant metaphyseal surfaces in the remodeled hip may be one factor in subsequent degenerative changes associated with SCFE.

Original languageEnglish (US)
Pages (from-to)419-424
Number of pages6
JournalJournal of Pediatric Orthopaedics
Issue number4
StatePublished - 1999


  • Impaction
  • Impingement
  • Metaphyseal remodeling
  • Osteoarthrosis of hip
  • Slipped epiphysis
  • Three-dimensional computer modeling

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Surgery
  • Orthopedics and Sports Medicine


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