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 .
Evaluation of a Femoral Stem with Reduced Stiffness: A Randomized Study with Use of Radiostereometry and Bone Densitometry
Background : Femoral stems with reduced stiffness were introduced in total hip arthroplasty to facilitate proximal load transfer and thereby reduce periprosthetic bone loss . Poor fixation and unacceptably high revision rates turned out to be a major problem with these prostheses . The purpose of the present study was to evaluate the early performance of a low-modulus stem ( one that is less stiff ) with the potential to address the problem of fixation by the use of a surface coating . The coating consisted of a titanium porous mesh proximally covered with a mixture of hydroxyapatite and tricalcium phosphate . Methods : Thirty-nine men and twenty-six women ( sixty-eight hips ) with noninflammatory arthritis were studied . The patients were r and omized to receive either a porous-coated composite stem with reduced stiffness ( Epoch ) or a stiff stem with a porous coating ( Anatomic ) . Both stems were inserted without cement , had a ceramic coating on the proximal two-thirds , and were supplied with tantalum beads . At the time of the operation , tantalum markers were also placed into the proximal part of the femur . The patients were followed for up to two years after the operation and were evaluated with use of repeated radiostereometric measurements , measurements of bone-mineral density , conventional radiography , and Harris hip scores . Results : Both stems showed optimum fixation with median subsidence and stem rotations that were close to zero . Repeated measurements of bone-mineral density revealed early loss of bone mineral in all Gruen regions in both treatment groups . The loss of bone mineral around the Epoch stems was significantly reduced at two years in Gruen regions 1 , 2 , 6 , and 7 ( p < 0.0005 to 0.04 ) . Measurements on postoperative radiographs showed no difference in stem positioning or fill , but the Epoch stems had significantly more endocortical contact on both the anteroposterior ( p < 0.0005 ) and the lateral radiograph ( p = 0.02).At two years postoperatively , the Epoch stems had fewer sclerotic lines surrounding the stem ( p £ 0.002 ) and less sclerosis at the tip of the prosthesis ( p = 0.001 ) compared with the Anatomic stems . The clinical results in terms of the Harris hip score , which was determined in all hips , and pain or discomfort , which was evaluated in thirty-seven hips treated at the same hospital , were not found to be different , with the numbers available . Conclusions : Contrary to previous studies of other design s with reduced stiffness , the Epoch stem achieved excellent primary fixation . Despite this rigid fixation , the proximal loss of bone-mineral density was less than that associated with the stem with a stiffer design . These results should encourage additional long-term studies with a larger patient population
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 .