Acetabular Bone Loss in Revision Hip Arthroplasty

Classification

  • Paprosky classification grades the defect on superior hip centre migration, ischial osteolysis, teardrop osteolysis and Kohler line integrity
  • Type 1 has minimal deformity with an intact rim and supportive columns
  • Type 2A is superior migration with a distorted but supportive rim, 2B has a deficient superior rim and 2C is medial wall loss with the cup medial to Kohler line
  • Type 3A is upward and lateral migration over 3 cm with bone loss from 10 to 2 o’clock
  • Type 3B is superomedial migration over 3 cm with Kohler line broken and severe ischial and teardrop lysis
  • AAOS classification describes segmental, cavitary, combined, pelvic discontinuity and arthrodesis defects

Investigations

  • AP pelvis and Judet views compare the hip centre with the contralateral side
  • CT with metal artefact reduction shows column integrity, pelvic discontinuity and bone stock
  • ESR, CRP and hip aspiration exclude infection before reconstruction
  • Pelvic discontinuity is a separation of the superior and inferior hemipelvis through the acetabulum
  • Review CT or angiography when intrapelvic components lie close to the iliac vessels

Management

  • Type 1 and 2 defects take a hemispherical porous coated cup on host bone, fixed with screws
  • Morselised graft fills contained cavities and medial wall defects
  • Type 3 defects need porous metal augments, a cup-cage construct or a custom triflange component
  • Structural allograft is less used because of late resorption and collapse
  • Pelvic discontinuity is treated with a cup-cage, a custom triflange or posterior column plating with a cup
  • Restore the hip centre as close to anatomical as bone allows

Complications

  • Dislocation, especially with a high hip centre or deficient abductors
  • Infection and re-revision
  • Vascular injury from medial wall screws or removal of intrapelvic components
  • Sciatic and femoral nerve injury
  • Failure of augment or cage fixation when ingrowth does not occur

Registry Data

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 15 October 2026.