Early migration pattern of the uncemented CLS stem in total hip arthroplasties

We performed this investigation to determine the possible migration starting immediately after surgery and the effect of different weightbearing regimens on the migration pattern of an uncemented hip stem (CLS). Stem migration was determined with radiostereometry analysis with baseline when the patients still were anesthetized. Subsequent examinations were done up to 1 year. Twenty-nine patients (mean age, 55 years; range, 26-63 years) were randomized to either unrestricted weightbearing combined with intensive physiotherapy from the first day after surgery or to partial weightbearing and a conservative training regimen for the first 3 months after surgery. At 1 week, subsidence was -0.03 mm in the unrestricted weightbearing group and 0.01 mm in the partial weightbearing group. At 1 year, subsidence was 1.01 mm in the unrestricted weightbearing group and 0.51 mm in the partial weightbearing group. One patient in the unrestricted weightbearing group had revision surgery because of aseptic loosening at 1.5 years after surgery. The CLS stem did not have any migration from the end the surgery until 1 week, but there was small migration from 1 week to 3 months after which the stem remained stable. The degree of early weightbearing did not affect the migration pattern.