Superior fixation of pegged trabecular metal over screw-fixed pegged porous titanium fiber mesh: a randomized clinical RSA study on cementless tibial components

Maiken Stilling, Frank Madsen, Anders Odgaard, Lone Rømer, Niels Trolle Andersen, Ole Rahbek, Kjeld Søballe

Abstract

BACKGROUND AND PURPOSE: Lasting stability of cementless implants depends on osseointegration into the implant surface, and long-term implant fixation can be predicted using radiostereometric analysis (RSA) with short-term follow-up. We hypothesized that there would be improved fixation of high-porosity trabecular metal (TM) tibial components compared to low-porosity titanium pegged porous fiber-metal (Ti) polyethylene metal backings.

METHODS: In a prospective, parallel-group, randomized unblinded clinical trial, we compared cementless tibial components in patients aged 70 years and younger with osteoarthritis. The pre-study sample size calculation was 22 patients per group. 25 TM tibial components were fixed press-fit by 2 hexagonal pegs (TM group) and 25 Ti tibial components were fixed press-fit and by 4 supplemental screws (Ti group). Stereo radiographs for evaluation of absolute component migration (primary effect size) and single-direction absolute component migration (secondary effect size) were obtained within the first postoperative week and at 6 weeks, 6 months, 1 year, and 2 years. American Knee Society score was used for clinical assessment preoperatively, and at 1 and 2 years.

RESULTS: There were no intraoperative complications, and no postoperative infections or revisions. All patients had improved function and regained full extension. All tibial components migrated initially. Most migration of the TM components (n = 24) occurred within the first 3 months after surgery whereas migration of the Ti components (n = 22) appeared to stabilize first after 1 year. The TM components migrated less than the Ti components at 1 year (p = 0.01) and 2 years (p = 0.004).

INTERPRETATION: We conclude that the mechanical fixation of TM tibial components is superior to that of screw-fixed Ti tibial components. We expect long-term implant survival to be better with the TM tibial component.

Original languageEnglish
JournalActa Orthopaedica (Online)
Volume82
Issue number2
Pages (from-to)177-86
Number of pages10
ISSN1745-3682
DOIs
Publication statusPublished - Apr 2011

Keywords

  • Absorptiometry, Photon
  • Adult
  • Aged
  • Arthroplasty, Replacement, Knee/adverse effects
  • Bone Screws
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Osteoarthritis, Knee/surgery
  • Prospective Studies
  • Prosthesis Design
  • Prosthesis Failure
  • Tibia/surgery
  • Titanium
  • Treatment Outcome

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