RSA Study of Furlong Evolution With and Without Collar

Evaluation of the Furlong Evolution Uncemented Hip Prosthesis With Special Emphasize on the Use of Collared Design or Not. A Prospective, Randomized Study Evaluated by RadioStereometric Analysis (RSA) and DXA.

The aim of this study is to further investigate the clinical and radiological importance of design changes in cementless hip prosthesis. The investigators have earlier evaluated the classical Furlong HAC total hip prosthesis and a first design change Furlong Active. Now a further development, Furlong Evolution, is to be evaluated. This prosthesis, furthermore, comes with and without a collar, and the investigators are going to randomize between the two. The investigators hypothesize that the new design will be easier to implant and will present equal or less migration than the older designs which would imply a favourable outcome in the long term. The investigators further hypothesize that the collar play no major part for the long term migration and bone remodelling. We will now do a 10 year follow up of the patients including RSA, DXA and PROMS

The stem has two versions, one with and one without a collar. This arm will have stems with a collar. The classical Furlong HAC had a collar.

The stem has two versions, one with and one without a collar. This arm will have stems without a collar. The classical Furlong HAC had a collar.

The stem has two versions, one with and one without a collar. The classical Furlong HAC had a collar.

This will measure the change in migration (translation and rotation around the x-, y-, and z-axis of the hip) over time. The migration pattern the first 2 years can predict the long term outcome.

This will measure the change in bone density around the prosthesis during the first important year. This will tell if there is a bone resorption around the stem or cup.

Hip disability and Osteoarthritis Outcome Score (HOOS) - this is a hip specific questionnaire that will measure how the operation has affected the patients function and pain situation.

Inclusion Criteria: Primary osteoarthritis of the hip necessitating primary hip replacement A femur considered suitable for uncemented fixation of the stem Biological age <75 years old at the inclusion time of the study. Exclusion Criteria: Rheumatoid arthritis Malignant disease Severe osteoporosis Earlier fracture or operation in the hip to be operated on Peroperative fracture Ongoing corticosteroid (oral) or immunosuppressive medication Personal disorders (dementia, alcohol or drug abuse etc) suspected of making completion of the trial uncertain.

Belfrage O, Weber E, Sundberg M, Flivik G. Preserved periprosthetic bone stock at 5 years post-operatively with uncemented short hip stem in both collared and collarless version. Arch Orthop Trauma Surg. 2022 Nov;142(11):3489-3496. doi: 10.1007/s00402-021-04225-z. Epub 2021 Nov 29.