B Assessment Bone Loss

IndicationsRevision THR CT scan Bone Defects


1.  Loosening
2.  Infection
3.  Instability
4.  Periprosthetic fracture


1.  Exclude infection
2.  Re-establish the structural integrity & bone stock
3.  Establish normal Joint mechanics
- restore the centre of rotation of the hip
4.  Initial rigid fixation of bone graft
5.  Adequate containment of the new prosthesis


Aetiology Bone Loss

1.  Osteolysis
2.  Surgical / iatrogenic (with implant removal)
3.  Acetabular dysplasia
4.  Fracture
5.  Infection


Preoperative Assessment

1.  Exclude infection
2.  Quantify bone loss





- Paprosky




- Paprosky


Femoral Bone Loss


Paprosky Classification

I Minimal metaphyseal cancellous bone loss / intact diaphysis
- i.e. seen after removal of uncemented component without biological ingrowth on surface

II Extensive metaphyseal cancellous bone loss / intact diaphysis
- often seen after removal of cemented prosthesis


Revision THR Paprosky II FemurRevision THR Paprosky II

IIIA Metaphysis severely damaged / > 4cm diaphyseal bone for distal fixation
- grossly loose femoral component
- first generation cementing techniques


Revision THR Paprosky IIIA FemurRevision THR Paprosky IIIA 3

IIIB Metaphysis severely damaged / < 4cm diaphyseal bone for distal fixation
- cemented with cement restrictor
- uncemented with substantial distal osteolysis


Infected THR Paprosky Type IIIA

IV Extensive metaphyseal and diaphyseal bone loss / isthmus non supportive


AAOS Classification

I Segmental
- proximal (partial or complete)           
- intercalary
- greater trochanter

II Cavitary
- cancellous
- cortical
- ectasia (dilatation)

III Combined segmental and cavity

IV Malalignment
- rotational
- angular

V Femoral Stenosis

VI Femoral Discontinuity


Acetabular Bone Loss

AAOS Classification

Type I    Segmental deficiencies

Peripheral -  superior / anterior / posterior

Central - medial wall absent


Revision THR Anterior wall segmental defect

Type II    Cavitary deficiencies

Peripheral  -  superior / anterior / posterior
Central - medial wall intact


Revision THR Cavitatory Deficiency CupRevision THR Contained Defect Cup CTRevision THR Cemented Cup Anterior Wall Intact

Type III    Combined deficiencies

Type IV     Pelvic discontinuity


Separation of anterior and posterior columns

Type V    Arthrodesis


Paprosky Classification

Based on ability of the remaining host bone

- to provide initial stability to a hemispherical cementless acetabular component

- until ingrowth occurs

Type 1    


Undistorted rim
- anterior and posterior columns intact
- no superior migration

- may have some contained deformities
- ishium, teardrop and Kohlers line intact

Type 2


Distorted but intact rim
- can support a hemispherical cementless implant


Revision THR Paprosky Type 2 Cup


Some distortion, minimal superior migration
- at least 50% good support by host bone
- anterior and posterior columns intact
- no substantial osteolysis of ischium or teardrop



- superomedial migration but superior rim intact


Revision Acetabulum Paprosky Type IIA



- < 1/3 superior deficit

- remainder is still supportive

- replace with allograft for bone stock



- medial migration to Kohlers, but wall intact

- rim is supportive

- manage as for protrusio


Revision Acetabulum Paprosky Type IICRevision THR Superior Migration Cup but Rim intact

Type 3


Non supportive rim
- columns not supportive, superior migration> 3 cm

- require structural allograft for support


Revision THR Type 3 Acetabulum

4 radiographic criteria

1.  Superior migration of the hip centre
- indicates damage to anterior and posterior columns
- supero-medial indicates greater damage to anterior column
- supero-lateral indicates greater damage to posterior column

2.  Ischial osteolysis
- bone loss inferior posterior column

3.  Teardrop osteolysis
- inferior anterior column and medial wall

4.  Position of the implant relative to Kohler’s line
- deficiency of anterior column



-  > 40% host bone contact

-  < 50% rim missing



- < 40% host bone contact

- > 50% rim missing