Proximal Tibial Bone Density Is Preserved After Unicompartmental Knee Arthroplasty
- First Online:
- 519 Downloads
Bone mineral density (BMD) in the proximal tibia decreases after TKA and is believed to be a factor in implant migration and loosening. Unicompartmental knee arthroplasty (UKA) is a less invasive procedure preserving knee compartments unaffected by degeneration. Finite element studies have suggested UKA may preserve BMD and that implants of differing stiffnesses might differentially affect BMD but these notions have not been clinically confirmed.
We therefore asked whether (1) proximal tibial BMD decreases after UKA, and (2) a cemented metal tibial component with a mobile polyethylene (PE) bearing would have greater BMD loss than a cemented PE tibial component.
We prospectively followed 48 patients who underwent 50 UKAs using one of two implants: one with a cemented metal tibial baseplate and a mobile PE insert (n = 26) and one with a cemented all-PE tibial component (n = 24). In followup we assessed pain and function (Oxford Knee Score, SF-12, The Knee Society Score©) and radiographs. BMD changes were assessed using quantitative CT osteodensitometry performed postoperatively and at 1 and 2 years after the index procedure.
Mean cancellous BMD decreased 1.9% on the medial side and 1.1% on the lateral side. Mean cortical BMD was static, decreasing 0.4% on the medial side and increasing 0.5% on the lateral side. The greatest observed difference between implants for any region was 3.7%. There were no differences in pain or functional outcome scores.
BMD was preserved 2 years after UKA with no major differences seen between implant types.
- 2.Australian Orthopaedic Association National Joint Replacement Registry. Annual Report. Adelaide, Australia: Australian Orthopaedic Association; 2010.Google Scholar
- 14.Lindstrand A, Stenström A, Ryd L, Toksvig-Larsen S. The introduction period of unicompartmental knee arthroplasty is critical: a clinical, clinical multicentered, and radiostereometric study of 251 Duracon unicompartmental knee arthroplasties. J Arthroplasty. 2000;15:608–616.PubMedCrossRefGoogle Scholar
- 17.New Zealand Joint Registry. Eleven Year Report. Christchurch, New Zealand: New Zealand Orthopaedic Association; 2010.Google Scholar
- 18.Petersen MM, Gehrchen PM, Østgaard SE, Nielsen PK, Lund B. Effect of hydroxyapatite-coated tibial components on changes in bone mineral density of the proximal tibia after uncemented total knee arthroplasty: a prospective randomized study using dual-energy x-ray absorptiometry. J Arthroplasty. 2005;20:516–520.PubMedCrossRefGoogle Scholar
- 25.Schmidt R, Pitto RP, Kress A, Ehremann C, Nowak TE, Reulbach U, Forst R, Müller L. Inter- and intraobserver assessment of periacetabular osteodensitometry after cemented and uncemented total hip arthroplasty using computed tomography. Arch Orthop Trauma Surg. 2005;125:291–297.PubMedCrossRefGoogle Scholar