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 .
Hydroxyapatite and tricalcium phosphate-coated cups with and without screw fixation: a randomized study of 64 hips.
Sixty-two patients ( 64 hips ) were provided with porous press-fit cups ( Trilogy ) , plasma-sprayed with a coating consisting of 70 % hydroxyapatite and 30 % tricalcium phosphate . The patients were r and omized to a cup with cluster holes for adjunctive screw fixation ( n = 30 ) or to a cup without holes ( n = 34 ) .  Radiostereometry  was used to study migration and wear . Up to 2 years median translations and rotations < 0.2 mm and < 0.2 degrees were recorded in the 2 groups , without any difference . The median annual proximal wear ( 0.11 and 0.12 mm ) was within the expected range despite the use of a ceramic coating , and it did not differ between the 2 design s. Radiolucent lines were frequently seen postoperatively but diminished during the follow-up without any sign of migration into the gaps . At 2 years , the median Harris scores were 99 points ( range , 51 - 100 points ) in the group with and 98 points ( range , 69 - 100 points ) in the group without screws . The results indicate that early fixation can be achieved for ceramic-coated press-fit cups without using additional screw fixation
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 .