Comparison of the fixation and stability of two bone substitutes: Pro Osteon and Calcibon by revision of the acetabulum prosthesis with RSA

A huge complication during revision surgery of an acetabulum cup prosthesis is
insufficient bone stock. The insufficient bone stock causes an insufficient
fixation and thereby early loosening of the new prosthesis. Several materials
have been proposed to replace the missing bone. Two of these materials are
Pro-osteon and Calcibon. Pro-Osteon is a hydroxyapitie bone graft with the same
strength and healing proportions as normal bone and is normally used in this
hospital. Calcibon is a synthetic bio resorbable calcium phosphate base bone
substitute. Which of these materials give the best clinical results is unknown.

Which of the products, Pro Osteon or Calcibon gives the best stability and
fixation of the acetabulum prosthesis by revision procedures.

Prospective randomized study

All patients will obtain a cemented Stanmore acetabulum cup prosthesis. By 10
patients the bone defects will be filled with Pro-Osteon and by 10 patients the
bone deficits will be filled with Calcibon. In the bone and on the prosthesis
RSA markers will be placed. Postoperative at 1 and 6 weeks and 4, 12 and 24
month, stereo-radiographs will be made to measure the migration of the
prosthesis with RSA.

The risks for the participants are the normal risks for revision acetabulum
surgery. Added burdens for the patient are 5 stereo roentgen photos and 5
questionnaires concerning the pain and function of 20 minutes each.