INTERPRETATION The guidelines have improved method ological reporting in RSA studies , but adherence to these guidelines is still relatively low .
BACKGROUND AND PURPOSE Guidelines for st and ardization of  radiostereometry ( RSA )  of implants were published in 2005 to facilitate comparison of outcomes between various research groups .
In this systematic review , we determined how well studies have adhered to these guidelines .
Second-generation Highly Cross-linked X3™ Polyethylene Wear: A Preliminary Radiostereometric Analysis Study
Background First-generation highly cross-linked polyethylene liners have reduced the incidence of wear particle-induced osteolysis . However , failed acetabular liners have shown evidence of surface cracking , mechanical failure , and oxidative damage . This has led to the development of second-generation highly cross-linked polyethylene , which has improved wear and mechanical properties and resistance to oxidation in vitro . Owing to its recent introduction , there are no publications describing its clinical performance . Questions / purpose sWe assessed early clinical wear of a second-generation highly cross-linked polyethylene liner and compared its clinical performance with the published results of hip simulator tests and with first-generation highly cross-linked polyethylene annealed liners . Patients and Methods Twenty-one patients were enrolled in a prospect i ve cohort study .  Clinical outcome and femoral head penetration were measured for 19 patients at 6 months and 1 and 2 years postoperatively . Results The median proximal head penetration was 0.009 mm and 0.024 mm at 1 and 2 years , respectively . The median two-dimensional ( 2-D ) head penetration was 0.083 mm and 0.060 mm at 1 and 2 years , respectively . The median proximal wear rate between 1 and 2 years was 0.015 mm/year . Conclusions The wear rate calculated was similar to the in vitro wear rate reported for this material ; however , it was less than the detection threshold for this technique . Although longer followup is required for wear to reach a clinical ly quantifiable level , this low level of wear is encouraging for the future clinical performance of this material .Level of Evidence Level IV , therapeutic study . See the Guidelines for Authors for a complete description of levels of evidence
INTERPRETATION The guidelines have improved method ological reporting in RSA studies , but adherence to these guidelines is still relatively low .
BACKGROUND AND PURPOSE Guidelines for st and ardization of  radiostereometry ( RSA )  of implants were published in 2005 to facilitate comparison of outcomes between various research groups .
In this systematic review , we determined how well studies have adhered to these guidelines .