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 .
A comparison of collared and collarless femoral components in primary cemented total hip arthroplasty: a randomized clinical trial.
Between July 1986 and November 1989 , 437 consecutive primary cemented total hip arthroplasties were performed using a straight-stemmed titanium alloy femoral component . Collared and collarless versions of this identical stem were r and omly chosen by computer allowing a comparison between 213 collared stems ( 198 patients ) and 224 collarless stems ( 209 patients ) . Diagnosis , sex , weight , and average age ( 72.8 years , collared ; 72.0 years , collarless ) were similar . Follow-up averaged 76 months ( collared ) and 72 months ( collarless ) with 49 patients followed for at least 10 years . Calcar-collar contact was noted in 205 hips ( 96 % ) on the initial postoperative radiograph . Early complications , including dislocations ( 5 % each group ) , were similar . Late complications included 3 deep infections ( 2 collared , 1 collarless ) and 2 postoperative femur fractures ( 1 each ) . Hip scores at the most recent follow-up averaged 91.2 and 90.1 in the collared and collarless groups . No or slight pain was noted in 93 % of collared and 91.5 % of collarless hips . Although no radiographic differences were noted in distal cortical hypertrophy , stem subsidence , and osteolysis , collarless hips lost significantly more medial femoral neck cortical bone ( average 0.90 mm vs 0.63 mm ) . A higher incidence of radiolucent lines in femoral zone VI ( 20.7 % vs 9.4 % ) was also noted in collarless hips
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 .