title: Factors Affecting Wear of Constrained Polyethylene Tibial Inserts in Total Knee Arthroplasty.
abstract: Wear in posterior-stabilized (PS) polyethylene tibial inserts depends on component position, limb alignment, and ligament balancing. Valgus-varus constrained (VVC) inserts are likely to be affected similarly. We aimed to compare wear characteristics of VVC and PS inserts and identify associated factors.
  
  
  
  This was a retrieval analysis (macroscopic and radiographic) of all 18 VVC liners collected from patients who underwent revision surgery from 1999 to 2011. These patients were matched to another group with PS inserts who underwent revision in the same time period.
  
  
  
  There was significantly more damage in the posts of the VVC group (13.0 ± 5.0, compared to 4.7 ± 1.9 in the PS group; P < .001). Within the VVC group, the total damage score and cold flow damage were significantly higher with excessive joint line changes (≥5 mm; P = .01). The excessive joint line elevation was associated with rotational wear pattern of the post (P = .004). Damage scores were increased with femoral component malposition (P = .04), anterior tibial slope (P = .04), and tibial component malposition (P = .04).
  
  
  
  Joint line elevation, femoral and tibial component malposition, and anterior tibial slope resulted in significantly more wear in the VVC inserts. Joint line elevation of >5 mm resulted in wear of the medial and lateral aspects of the post, femoral valgus resulted in cold flow wear of the anterior post, and tibial valgus and anterior slope resulted in wear of lateral aspect of the post.
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hospital, Academia Level 4, Singapore; Division of Orthopaedic Surgery, Joint Replacement Institute, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Hee-Nee
authors.initials: HN
authors.lastname: Pang
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hospital, Academia Level 4, Singapore.
authors.forename: Hamid Rahmatullah
authors.initials: HR
authors.lastname: Bin Abd Razak
authors.affiliation: Division of Orthopaedic Surgery, Joint Replacement Institute, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Jamieson
authors.affiliation: Division of Orthopaedic Surgery, Joint Replacement Institute, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Teeter
authors.affiliation: Division of Orthopaedic Surgery, Joint Replacement Institute, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Douglas D R
authors.initials: DDR
authors.lastname: Naudie
authors.affiliation: Division of Orthopaedic Surgery, Joint Replacement Institute, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: MacDonald
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D005260:Female; D005269:Femur / Q000601:surgery; D006801:Humans; D007595:Joint Prosthesis; D007719:Knee Joint / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020959:Polyethylene / Q000737:chemistry*; D011475:Prosthesis Failure; D012086:Reoperation; D013977:Tibia / Q000601:surgery*
chemical_list: D020959:Polyethylene
keywords: PE; VVC; constrained; polyethylene; revision; wear