The Charnley prosthesis had by far the best and most comprehensive evidence base with better than 90 % implant survival after about 10 years .
Some uncemented stems have shown promising medium-term outcome , but no combination of uncemented cup and stem fulfilled the benchmark criterion of > or = 90 % implant survival at 10 years , which we propose as a minimum requirement for unrestricted clinical use for prostheses used in primary THR .
We have conducted a systematic review of the scientific literature concerning outcome and clinical effectiveness of  prostheses used for primary total hip replacement ( THR ) in Norway .
The Charnley versus the Spectron hip prosthesis: radiographic evaluation of a randomized, prospective study of 2 different hip implants.
A total of 410 hips were r and omized to treatment with either a Charnley ( 206 hips ) or a Spectron ( 204 hips ) total hip arthroplasty .  The patients were operated on by a st and ardized procedure using a contemporary cementing technique and were followed after 1 , 3 , 5 to 6 , and 10 years . The postoperative radiographs showed a significantly increased rate of malalignment and consequently low grade of cement mantle quality of the Charnley stem compared to the Spectron . No differences concerning cement mantle quality or positioning were found between the Charnley ogee cup and the metal-backed Spectron . Evaluation of the follow-up radiographs revealed 10 loose Charnley stems and 1 loose Spectron stem and 4 loose Charnley ogee cups and 23 loose Spectron metal-backed cups . The differences of revision rate for the femoral and acetabular components of the 2 prostheses were significant ( P = .03 , Charnley femoral component more frequent ; P = .03 , Spectron acetabular component more frequent ) . The radiographic evaluation strengthened this disparity . Poor wear characteristics of the metal-backed Spectron cup are perhaps the main reason for the highly significant difference in mechanical failure rate between the 2 cups . We therefore propose that metal-backing of cemented cups should be avoided , at least when combined with larger femoral heads . The difficulty in positioning the Charnley stem with an adequate cement mantle , especially in the absence of trochanteric osteotomy , might explain the inferior Charnley stem longevity in this study
The Charnley prosthesis had by far the best and most comprehensive evidence base with better than 90 % implant survival after about 10 years .
Some uncemented stems have shown promising medium-term outcome , but no combination of uncemented cup and stem fulfilled the benchmark criterion of > or = 90 % implant survival at 10 years , which we propose as a minimum requirement for unrestricted clinical use for prostheses used in primary THR .
We have conducted a systematic review of the scientific literature concerning outcome and clinical effectiveness of  prostheses used for primary total hip replacement ( THR ) in Norway .