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 .
Influence of Design Variations on Early Migration of a Cemented Stem in THA
The clinical results of using different cemented stems in total hip arthroplasty may vary because of shape , surface finish , and choice of metal alloy . Less is known about the influence of size and offset using one and the same design . Data from 140 patients ( 140 hips ) of a cohort constituting 197 patients ( 231 hips ) implanted with cemented Spectron Primary stems were extracted from patients studied in four r and omized studies primarily design ed for other purpose s. Stem size ( 1 , 2 , 3 , or larger ) , normal/extra offset , neck length and true offset ( horizontal length between the stem and head center of the inserted modular implant ) were recorded in millimeters . The radiographic appearance of the cementing was grade d on the immediate postoperative radiograph according to Barrack . The patients were examined with  radiostereometric analysis  of  stem migration  for a 2-year followup period . Stem Size 1 ( the smallest ) showed an insignificant increase in subsidence compared with the bigger sizes . Using stepwise linear regression analysis , the quality of the cementing ( Barrack C2 ) was the only parameter that had any certain influence of the subsidence at 2 years . Stem size 2 tended to show minimum valgus alignment and sizes 1 and 3 and bigger showed minimum varus tilting . Our findings suggest that placement of the stem with the tip against the posterior cortex ( C2 ) and stem size influence the primary fixation in different ways . This effect is small , however , indicating that further confirmation with longer followup is necessary . Level of Evidence : Therapeutic Level II-1 ( prospect i ve cohort 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 .