Abstract
A common finding in acetabular revisions is loss of medial bone stock. Using a standard cementless hemispherical component, alternatives for reconstruction include medialisation of the cup, medial particulate allograft with rim fixation on host bone, or use of a “mega-cup”. A cementless shell that has 6 mm of lateral augmentation is useful in restoring the joint centre while at the same time achieving implant stability and increasing host bone contact without loss of additional bone.
From 1991 to 2000, a total of 142 acetabular revisions were performed with the Arthropor TM DP+6 implant (Joint Medical Products/J& J/DePuy). These patients have been prospectively followed bi-annually with Harris Hip Scores and monitoring of complications and radiographic findings. Average follow-up is 5 years (range 2 to 11 years).
Implant survivorship is 100%. There have been seven re-operations: one for infection (debrided), two for femoral revision and four head/liner changes for recurrent dislocations. Dislocation incidence is 7.8%. The average Total Harris Score at 5 years is 74.3, with an average Harris Pain Score of 34.9 (out of a maximum of 44). Radiographic analysis showed frequent zone 3 radiolucent zones. Initial migration of > 2 mm with subsequent stabilisation occurred in 18%. The joint centre was restored to within 5 mm of the contralateral hip in 85% of cases.
We have found this type of implant to be efficacious in the more common acetabular revisions where the loss of bone stock is mainly medial/cavitary, with an intact posterior column and small medial segmental defects.
The abstracts were prepared by Nico Verdoschot. Correspondence should be addressed to him at Orthopaedic Research Laboratory, Universitair Medisch Centrum, Orthopaedie / CSS1, Huispost 800, Postbus 9101, 6500 HB Nijmegen, Th. Craanenlaan 7, 6525 GH Nijmegen, The Netherlands.
