Finally , with use of a variety of vali date d measures , there was no difference between the two groups in terms of functional status at two , eight , and ten years , regardless of the measure used .
A less expensive all-polyethylene component as part of a total knee arthroplasty has results equivalent to those obtained with a cemented metal-backed tibial component .
BACKGROUND The cost of the implant as part of a total knee arthroplasty accounts for a substantial portion of the costs for the overall procedure : all-polyethylene tibial components cost considerably less than cemented metal-backed tibial components .
We performed a systematic review of the literature to determine whether the clinical results of lower-cost all-polyethylene tibial components were comparable with the results of a more expensive metal-backed tibial component .
The Effect of Hydroxyapatite on the Micromotion of Total Knee Prostheses. A Prospective, Randomized, Double-Blind Study*
A prospect i ve , r and omized , double-blind study was performed to evaluate three different means of fixing tibial components  during total knee arthroplasty . Eleven components fixed with cement , ten hydroxyapatite-coated components fixed without cement  , and ten noncoated components fixed without cement were studied . A posterior cruciate ligament-retaining total condylar implant was used . Micromotion of the components was assessed with roentgen stereophotogrammetric analysis during the two-year follow-up period . There were no significant differences among the patients with regard to age ( mean [ and st and ard deviation ] , 68 ± 11.6 years ) , body-mass index ( mean , 23 ± 2.8 kilograms per square meter ) , or stage of osteoarthrosis ( mean , 4 ± 2.4 according to the classification system of Ahlbäck and 5 ± 0.6 according to that of Larsen et al. ) . The diagnosis was osteoarthrosis in five knees , and it was rheumatoid arthritis in twenty-six .  The clinical scores were similar among the study groups . According to the system of the Knee Society , the mean preoperative functional score was 10 ± 2.9 points and the mean preoperative knee score was 24 ± 3.2 points . At the two-year follow-up evaluation , these scores were 41 ± 8.3 and 79 ± 3.2 points , respectively . A significant difference with regard to micromotion was found between the noncoated components fixed without cement and the hydroxyapatite-coated components fixed without cement as well as between the noncoated components fixed without cement and the components fixed with cement ( p < 0.001 , analysis of variance ) . The hydroxyapatite-coated components fixed without cement and the components fixed with cement both had far less micromotion along the longitudinal axis ( subsidence ) throughout the follow-up period than did the noncoated components fixed without cement . At the two-year follow-up evaluation , the subsidence of the noncoated components was -0.73 ± 0.924 millimeter , the subsidence of the cemented components was -0.05 ± 0.109 millimeter , and the subsidence of the hydroxyapatite-coated components was -0.06 ± 0.169 millimeter . The cemented components as well as the hydroxyapatite-coated components also had less translation along the transverse axis ( p < 0.001 , analysis of variance ) and the sagittal axis ( p < 0.001 , analysis of variance ) compared with the noncoated components . In conclusion , micromotion of hydroxyapatite-coated tibial components fixed without cement was similar to that of tibial components fixed with cement . Therefore , hydroxyapatite , a biological mediator , may be necessary for the adequate fixation of tibial components when cement is not used
Finally , with use of a variety of vali date d measures , there was no difference between the two groups in terms of functional status at two , eight , and ten years , regardless of the measure used .
A less expensive all-polyethylene component as part of a total knee arthroplasty has results equivalent to those obtained with a cemented metal-backed tibial component .
BACKGROUND The cost of the implant as part of a total knee arthroplasty accounts for a substantial portion of the costs for the overall procedure : all-polyethylene tibial components cost considerably less than cemented metal-backed tibial components .
We performed a systematic review of the literature to determine whether the clinical results of lower-cost all-polyethylene tibial components were comparable with the results of a more expensive metal-backed tibial component .