Radiostereometric analysis in hip revision surgery - optimal time for index examination - 6 patients revised with impacted allografts and cement followed weekly for 6 weeks

We revised the hip (6 stems and 5 sockets) with impacted morselized allogra fts and cement in 6 patients. We followed prosthetic migration by roentgen radiostereometric analysis (RSA) every 7th day for 6 weeks after the first (index) examination performed on the first postoperative day before mobiliz ation. Most of the migration occurred during the first 2 weeks. In most cas es more than half of the distal stem migration was seen between the Ist and 14th days. In all cases, the stem and socket migrations slowed down gradua lly and several prosthetic components had become stable after 5 weeks. We c onclude that it is essential to perform the index RSA examination on the Is t or 2nd day after surgery and to state when and how weight bearing should be permitted. Otherwise it will be difficult to compare prosthetic migratio n in various studies and define normative values for migration predicting s urvival.