early stability of the delta-tt cup with polyethylene insert versus a ceramic insert. a rsa study.

Conditions: Osteoarthrosis

Summary: the goal of this study is to study the stability of the delta-tt cup with polyethylene insert and the delta-tt cup with ceramic insert both combined with the h-max femoral stem by means of rsa to assess whether the differences in stiffness of the cup will have an influence on incorporation and mechanical stability. it is hypothesized that there will be more micromotion on the short-term (\<2 years) in the patients with the ceramic insert because of the higher stiffness, however, all components will be considered stable on the short and long-term.

rationale: roentgen stereophotogrammetric analysis (rsa) is a very accurate measurement technique used to obtain micromotion of the implants relative to inserted tantalum markers in the surrounding bone. using rsa, long-term predictions of prosthetic loosening can be made based on a two years follow-up. therefore, it is recommended to analyse all (new) prosthetic components by means of rsa. objective: the goal of this study is to study in a randomised trial the stability of the delta-tt cup with polyethylene insert and the delta-tt cup with ceramic insert both combined with the h-max femoral stem by means of rsa to assess whether the differences in stiffness of the cup will have an influence on incorporation and mechanical stability. it is hypothesized that there will be more micromotion on the short-term (\<2 years) in the patients with the ceramic insert because of the higher stiffness, however, all components will be considered stable on the short and long-term. secondary goal is to compare the stability of the c2 femoral stem, to the h-max femoral stem as well as to compare it to relevant migration results of similar stems from the literature. these rsa results will contribute to knowledge about the early stability and long-term prosthetic loosening of these cementless stems.

Eligibility criteria:
inclusion criteria: * patients scheduled to undergo primary total hip replacement. * patient is able to understand the meaning of the study and is willing to sign the ethical committee approved, study-specific informed patient consent form. * ability and willingness to follow instructions and to return for follow-up evaluations. * the subject is a male or non-pregnant female between 18 and 75 years of age. exclusion criteria: * the subject is morbidly obese, defined as body mass index (bmi) of \> 40. * the subject will be operated bilaterally. * patients having a deformity or disease located in other joints than the hip that needs surgery and is limiting their ability to walk. * the subject has an active or suspected latent infection in or about the hip joint. * the subject has a neuromuscular or neurosensory deficiency, which would limit the ability to assess the performance of the device. * the subject has a systemic or metabolic disorder leading to progressive bone deterioration. * the subject's bone stock is compromised by disease or infection which cannot provide adequate support and/or fixation to the prosthesis. * female patients planning a pregnancy during the course of the study. * the patient is unable or unwilling to sign the informed consent specific to this study. * subject deemed unsuitable for participation in the study based on the investigator's judgement.