Implant migration after early weightbearing in cementless hip replacement.
Twenty-nine patients (five women and 24 men) with an average age of 47 years (range, 24-59 years) had 37 total hip arthroplasties using a hydroxyapatite-coated double-wedge press-fit femoral component. All patients had a Type A bone quality. Patients were either mobilized with weightbearing as tolerated or toe-touch weightbearing for 6 weeks postoperatively. After 6 weeks all patients were advanced to weightbearing as tolerated. Radiostereometric analysis radiographs were taken at 3 days, 6 weeks, and 6 months postoperatively to measure migration of the femoral component. Radiostereometric analysis revealed no difference in stem migration between the two groups as defined by maximal total point migration. There was a difference in the vertical (proximal-distal) migration within the first 6 weeks between groups (0.81 mm versus 0.13 mm), but not afterwards (0.17 mm versus 0.18 mm). Continuous migration after 6 weeks was observed in three patients from each group. There was no loosening in either group within a 2-year followup. Weightbearing as tolerated is recommended for young patients with excellent bone quality after cementless total hip arthroplasty with a double-wedge press-fit femoral component.


METHODS
Diagnostic study, Level I (testing of previously developed diagnostic criteria in series of consecutive patients--with previously applied reference gold standard). See the Guidelines for Authors for a complete description of levels of evidence.
Hospital for Special Surgery, New York, NY 10021, USA. Bottner@uni-muenster.de
Friedrich
F
Bottner
Mark
M
Zawadsky
Edwin P
EP
Su
Mathias
M
Bostrom
Lars
L
Palm
Leif
L
Ryd
Thomas P
TP
Sculco
D000328:Adult; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D020099:Coated Materials, Biocompatible; D017886:Durapatite; D005260:Female; D006621:Hip Joint / Q000502:physiology; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000601:surgery*; D011446:Prospective Studies; D011475:Prosthesis Failure; D011859:Radiography; D016474:Weight-Bearing
D020099:Coated Materials, Biocompatible; D017886:Durapatite