From 1985 to 1995, 417 patients with dislocated medial femoral neck fractures (Garden III-IV) were treated with hemiarthroplasty using a Biolox ceramic head. The average patient age at the time of operation was 81.5 years. A total of 140 survivors was available for follow-up examination with a mean prosthesis longevity of 55.8 months. The Harris hip score recorded a mean of 70.6 points. At the time of follow up, 5 patients had severe hip pain, and in 8 the roentgenographic examination revealed protrusio acetabuli. Five of these 8 patients underwent revision surgery for replacement of the cup, leaving the stem in situ.