The purpose of this study is to compare hemiarthroplasty (HAP) with total hip arthroplasty (THA), performed by trained arthroplasty surgeons with the use of large femoral heads for the treatment of displaced femoral neck fractures in mobile independent elderly patients, to determine the impact of these surgical options on the short term functional outcomes and complication rates, namely dislocation and the need for further surgery.

This is a single-blinded prospective randomized clinical trial comparing functional outcome and complication rates of 40 patients treated with all cemented THA to a control group of 40 patients treated with cemented bipolar HAP, in a 2 years followup.

The primary endpoint is the Oxford hip score (OHS) at last followup as a measure of functional outcome. Secondary endpoints include the SF-36 score, walking distance and rates of postoperative dislocation, component loosening, need for revision and postoperative mortality.

Inclusion Criteria:

• 1. Acute femoral neck fracture.
• 2. Age between 70 and 90 years old.
• 3. Independent community ambulator (more than 0.5km, without the aid of another person. The use of a cane is permitted) prior to fracture.
• 4. Abbreviated mental test score > 6 .

Exclusion Criteria:

• 1. Pathological fracture (excluding osteoporosis).
• 2. Rheumatoid arthritis.
• 3. Symptomatic arthrosis of the involved hip.
• 4. Neurological disorder that may significantly influence walking ability and/or tendency to dislocate.
• 5. Chronic corticosteroid use.
• 6. Concomitant other fracture.
• 7. Very high surgical risk.