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 .
The migration patterns of two versions of the Furlong cementless femoral stem: a randomised, controlled trial using radiostereometric analysis.
We have evaluated the difference in the migration patterns over two years of two  cementless stems  in a r and omised , controlled trial using radiostereophotogrammetric analysis ( RSA ) . The implants studied were the Furlong HAC stem , which has good long-term results and the Furlong Active stem , which is a modified version of the former design ed to minimise stress concentrations between the implant and bone , and thus to improve fixation . A total of 23 Furlong HAC and 20 Furlong Active stems were implanted in 43 patients .  RSA examinations were carried out immediately post-operatively and at six , 12 and 24 months post-operatively . The subsidence during the first year in the Furlong HAC stem , was approximately one-third that of the Furlong Active stem , the measured mean subsidence of the femoral head at six months being 0.27 mm ( 95 % confidence interval ( CI ) 0.03 to 0.51 ) and 0.99 mm ( 95 % CI 0.38 to 1.60 ) , respectively ( p = 0.03 ) . One Active stem continued to subside during the second year . All hips , regardless of the type of stem were clinical ly successful as judged by the Oxford hip score and a derived pain score without any distinction between the two types of stem . The initial stability of the Furlong Active stem was not as good as the established stem which might compromise osseo-integration to the detriment of long-term success . The changes in the geometry of the stem , to minimise stress have affected the attainment of initial stability
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 .