title: Metal block augmentation for bone defects of the medial tibia during primary total knee arthroplasty.
abstract: BACKGROUND
  Stable and well-aligned placement of tibial components during primary total knee arthroplasty is challenging in patients with bone defects. Although rectangular block-shaped augmentations are widely used to reduce the shearing force between the tibial tray and bone compared with wedge-shaped augmentations, the clinical result remains unclear. This study aimed to evaluate the outcome of primary total knee arthroplasty with metal block augmentation.
  
  
  METHODS
  We retrospectively reviewed the 3- to 6-year follow-up results of 33 knees that underwent total knee arthroplasty with metal block augmentation (metal-augmented group) for bone defects of the medial tibia and 132 varus knees without bone defects as the control group. All surgeries were performed using posterior-stabilized cemented prostheses in both groups. Cemented stems were routinely augmented when the metal block was used.
  
  
  RESULTS
  There were no differences in implant survival rates (100% in metal-augmented and 99.2% in control) or knee function scores (82 points in metal-augmented and 84 points in control) between the two groups at the final follow-up examination (P = 0.60 and P = 0.09, respectively). No subsidence or loosening of the tibial tray was observed. Of 33 metal-augmented total knee arthroplasties, a nonprogressive radiolucent line beneath the metal was detected in 10 knees (30.3%), and rounding of the medial edge of the tibia was observed in 17 knees (51.5%).
  
  
  CONCLUSIONS
  The clinical results of total knee arthroplasty with metal augmentation were not inferior to those in patients without bone defects. However, radiolucent lines were observed in 30.3%.
authors.affiliation: Department of Orthopaedic Surgery, Nekoyama Miyao Hospital, 14-7 Konan, Chuo-ku, Niigata 950-1151, Japan. s8058@nms.ac.jp.
authors.forename: Sachiyuki
authors.initials: S
authors.lastname: Tsukada
authors.forename: Motohiro
authors.initials: M
authors.lastname: Wakui
authors.forename: Munenori
authors.initials: M
authors.lastname: Matsueda
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation / Q000379:methods*; D018786:Bone Substitutes / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology; D007720:Knee Prosthesis; D008297:Male; D008670:Metals; D008875:Middle Aged; D011474:Prosthesis Design; D011859:Radiography; D012189:Retrospective Studies; D013977:Tibia / Q000601:surgery*; D016896:Treatment Outcome
chemical_list: D018786:Bone Substitutes; D008670:Metals