On of the liners has been taken from the market

The purpose of this study is to analyse if the alignment of the stem and the number of complications of the new resorbable PEGT/PBT centralizer are comparable to the standard PMMA centralizer during the placement of an uncemented Bihapro hip prosthesis.

For a correct placement and early fixation of an uncemented hip prosthesis, a centralizer is used. Normally, the centralizer is made of PMMA, the same material as bone cement. When a revision is needed, PMMA is difficult to remove, which is one of the reason not to use a cemented hip prosthesis. With a PMMA centralizer, still PMMA will remain in the bone and needs to be removed in case of a revision. PEGT/PBT is a reabsorbable material, which gives stability during the first month after the placement of the hip prosthesis. However, PEGT/PBT is reabsorped afterwards and, therefore, will not interfere with a revision procedure.

The goal of this study is to analyse if the PEGT/PBT is as safe as PMMA in terms of alignment, direct postoperative complications and clinical results.

Therefore, 100 patients indicated for a cementless Bihapro hip prosthesis which have signed an informed consent are included and randomised over the used centralizers using a weighted randomisation method. All patients will be treated equally. The patients are examined preoperatively, 1 day, 6 weeks, 3, 6, 12, 24 en 48 months postoperatively using an X-ray, the Harris hip score and a patient questionnaire, the Womac and SF36.

Inclusion Criteria:

• Age between 18 and 75 years
• Diagnosis: Osteoarthritis
• Indicated for a primary hip prosthesis

Exclusion Criteria:

• Previous hip surgery
• No informed consent
• Active infection in hip
• Immature skeleton
• Rheumatoid arthritis, M. Paget