80 patients eligible for a total hip replacement (THR) mainly due to primary osteoarthritis were recruited from the waiting list for hip arthroplasty at a university hospital in Sweden. The patients were randomized to either CFP or Corail stem, both groups received Delta cup from Lima. Randomisation was done using envelopes. Patients could only participate with one hip. Patients are evaluated with different questionnaires, radiographs and RSA analysis.

The concept of femoral neck preserving hip replacement is intended for the young and active patients. By preserving proximal bone load, the transmission to the proximal femur is supposed to improve and future revision surgery would be facilitated. The hypothesis is that a more conservative resection of the femoral neck could lead to better clinical outcomes compared to a conventional stem. The clinical outcomes and the fixation of a short femoral stem were therefore compared with a stem of standard length. 83 patients were included in our randomized controlled trial where patients either received a Collum Femoris Preserving (CFP) stem or a Corail hip stem. Clinical outcomes are being assessed, plain radiographs are studied and the early migration is being measured using radiostereometric analysis. All of the patients have gone through 1 year follow-up. The 2 years results will be available at the end of 2017.

Inclusion Criteria:

• primary osteoarthritis of hip
• secondary osteoarthritis due to hip dysplasia or Perthes under condition that the collum anatomy is well preserved and largely unaffected by the primary disease
• avascular necrosis of femoral head
• anatomy suitable for both designs according to preoperative planning

Exclusion Criteria:

• previous treatment with cortisone
• generalized joint disease