Randomized comparison between 3 surface treatments of a single anteverted stem design: 84 hips followed for 5 years.
Eighty patients (84 hips) randomly received an anteverted cobalt-chromium stem (Lubinus SP2; Waldemar Link, Hamburg, Germany) with matte, polymethyl methacrylate-coated, or polished surface (uncollared). Radiostereometry was used to study migration and wear; and the bone mineral density was studied with dual-energy x-ray absorptiometry at 6 months, 1 year, 2 years, and 5 years. The polished stems had subsided 0.1 to 0.2 mm more at 6 months and 0.3 to 0.4 mm more at 5 years than the matte and precoated versions (P < .0001) and subsided mainly inside the cement mantle. The rotations of the stem and the migration and wear of the cemented cup did not differ between the 3 groups. After 1 and 2 years, the polished stems had lost significantly less bone mineral in Gruen zones 1, 2, 6, and 7 (P = .004 to .03); but this difference had disappeared after 5 years. The period of improved bone remodeling around the polished version coincided with the early period of increased subsidence, suggesting that stem motions inside the mantle resulted in a favorable loading of the proximal femur. Our observations suggest that alternative shapes could be possible on future polished femoral stem designs.
Thien
Truike M
TM
Department of Orthopaedics, Sahlgrenska University Hospital, Mölndal, Sweden.
Thanner
Jonas
J
Kärrholm
Johan
J
D015502:Absorptiometry, Photon; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation* / Q000379:methods; D001843:Bone Cements; D015519:Bone Density / Q000502:physiology; D002858:Chromium Alloys; D005260:Female; D005269:Femur / Q000502:physiology; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery*; D019904:Polymethyl Methacrylate; D011474:Prosthesis Design; D011475:Prosthesis Failure; D016896:Treatment Outcome
D001843:Bone Cements; D002858:Chromium Alloys; D019904:Polymethyl Methacrylate