title: Changes in bone mineral density of the proximal tibia after uncemented total knee arthroplasty. A prospective randomized study.
abstract: OBJECTIVE
  Regenerex is a novel porous titanium construct with a three-dimensional porous structure and biomechanical characteristics close to that of normal trabecular bone. The aim of this study was to evaluate the adaptive bone remodeling of the proximal tibia after uncemented total knee arthroplasty (TKA) using a tibial tray with this novel coating compared to a well-proven standard porous coated (PPS) tibial tray.
  
  
  METHODS
  Sixty patients scheduled for TKA were randomized to receive either a Regenerex (n = 31) or a PPS tibial component (n = 29). Changes in bone mineral density (BMD) of the proximal tibia were measured at three, six, 12 and 24 months by dual-energy X-ray absorptiometry (DEXA).
  
  
  RESULTS
  In the lateral region (ROI 3), a significant increase in BMD was seen in both groups at three, six, and 12 months after surgery. The relative increase at 12 months was 8.1 % (P = 0.007) for the PPS group and 6.5 % (P = 0.002) for the Regenerex group. Positive values were retained at 24 months in both groups. At 24 months BMD in the distal region below the central stem (ROI 1) had decreased in the PPS group by 3.4 % (P = 0.005) and in the Regenerex group by 2.4 % (P = 0.17). In the medial region (ROI 2) BMD remained unchanged at all follow-up evaluations in both groups. There were no significant differences between the two groups (P = 0.45) in any ROI at any follow-up evaluation.
  
  
  CONCLUSIONS
  The significant increase in BMD of the lateral proximal tibia plateau with very limited changes medially and distally seen in both implants suggests that the novel porous titanium construct Regenerex and the PPS implant have a pronounced beneficial effect with regard to maintaining periprosthetic BMD in all regions of interest investigated.
authors.affiliation: Department of Orthopaedic Surgery, Rigshospitalet University Hospital, Copenhagen, Denmark. nikolajdoktor@gmail.com.
authors.forename: Nikolaj
authors.initials: N
authors.lastname: Winther
authors.affiliation: Department of Orthopaedic Surgery, Rigshospitalet University Hospital, Copenhagen, Denmark.
authors.forename: Claus
authors.initials: C
authors.lastname: Jensen
authors.affiliation: Department of Orthopaedic Surgery, Gentofte Hospital, Hellerup, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Petersen
authors.affiliation: Department of Orthopaedic Surgery, Gentofte Hospital, Hellerup, Denmark.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lind
authors.affiliation: Department of Orthopaedic Surgery, Rigshospitalet University Hospital, Copenhagen, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Schrøder
authors.affiliation: Department of Orthopaedic Surgery, Rigshospitalet University Hospital, Copenhagen, Denmark.
authors.forename: Michael
authors.initials: M
authors.lastname: Petersen
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods*; D015519:Bone Density / Q000187:drug effects / Q000502:physiology*; D016723:Bone Remodeling / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016062:Porosity; D011446:Prospective Studies; D013977:Tibia / Q000503:physiopathology / Q000601:surgery*
keywords: Bone mineral density; Randomized controlled trial; Regenerex; Total knee arthroplasty; Trabecular metal