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 .
Hybrid Total Hip Arthroplasty with a Precoated Offset Stem: Four to Nine-Year Results*
Background : Use of modern cementing techniques for fixation of femoral components in total hip arthroplasty has had excellent clinical and radiographic results in most patients . However , several authors have described early loosening of femoral components with roughened and precoated finishes . The purpose of this study was to examine the performance of the precoated Iowa stem , which has increased offset , and to compare the results with those of another cemented precoated femoral component with st and ard offset used at our institution . Methods : We carried out a prospect i ve analysis of 102 primary hybrid total hip arthroplasties ( a cementless acetabular component and a cemented femoral component ) performed with use of the Iowa femoral component in ninety-five patients at our institution . The Iowa stem was used in hips that required greater offset than is available with st and ard stems as determined by preoperative templating . The average age of the patients at the time of the index procedure was sixty-nine years . Sixteen patients ( seventeen hips ) died before the forty-eight-month minimum follow-up period had elapsed . Two patients were lost to follow-up , and radiographic follow-up was incomplete for one . The mean duration of clinical and radiographic follow-up of the remaining eighty-two hips in the seventy-six surviving patients was sixty-five months ( range , forty-eight to 104 months ) . Results : The average preoperative Harris hip score of 47 points ( range , 16 to 69 points ) improved to an average of 87 points ( range , 24 to 100 points ) at the time of the review . Two hips underwent femoral component revision . Four femoral stems were radiographically loose at an average of thirty-four months . Femoral osteolysis was seen in five hips ( 6 percent ) at an average of fifty-four months postoperatively . No acetabular component was revised because of aseptic loosening . According to Kaplan-Meier analysis , the seven-year survival rate , with an end point of femoral revision , osteolysis , or stem debonding , was 90.6 percent ( 95 percent confidence interval , 0.87 to 0.94 ) . Conclusions : The prevalence of revision , osteolysis , and loosening after total hip arthroplasty with the  Iowa femoral component  at our institution was higher than that seen in our series of Harris Precoat stems , which had a survival rate of 98.4 percent ( 95 percent confidence interval , 0.97 to 1.00 ) at ten years with the same end points . The design of the Iowa stem may make it difficult to achieve a good cement mantle , and , in combination with the geometry and increased offset of the stem , may compromise the long-term survival of this cemented femoral component
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 .