[An investigation on failure mechanisms of primary 327 hip arthroplasties]. 
To summarize the detailed failure mechanisms of revision hip arthroplasties and related risk factors.  From November 1988 to July 2008 revision of total hip arthroplasties was performed in 327 patients.  The medical history, clinical and imaging material and operation records were investigated.  Regarding revision as the end point of the study, the reasons for 327 revision arthroplasties were aseptic loosening in 226 hips (69.1%), infection in 52 hips (15.9%), periprosthetic fracture in 22 hips (6.7%), instability in 17 hips (5.2%), stem fracture in 5 hips (1.5%) and liner dissociation in 5 hips (1.5%).  The main failure mechanisms of primary hip arthroplasties are aseptic loosening and infection of implants, which could be attributed to improper selection of operation indications and implants and limitations to surgical philosophy and technique.