title: Knee moments after unicompartmental knee arthroplasty during stair ascent.
abstract: BACKGROUND
  For unicompartmental knee arthroplasty (UKA), abnormal loading on the tibiofemoral joint could exacerbate knee osteoarthritis or implant wear. Joint moments are an indirect measure of such loading. However, little is known about knee moments of patients with UKA, tempering enthusiasm for its use.
  
  
  OBJECTIVE
  In patients with UKAs performing stair ascent, we (1) determined whether interlimb differences for knee moments are demonstrated, (2) described the knee kinetics of patients with medial and lateral UKAs, and (3) investigated possible factors that might influence the knee abductor moments.
  
  
  METHODS
  In our cross-sectional study, we recruited 26 patients with UKA with nondiseased contralateral limbs who performed stair ascent. Seventeen patients had medial UKAs and nine had lateral UKAs. Paired t-tests and CIs were applied to determine interlimb differences within each UKA group for peak knee moments and times to peak moments.
  
  
  RESULTS
  During stair ascent, the medial UKA group displayed greater peak extensor moments for the nondiseased compared to the UKA limb (p = 0.030), whereas the lateral UKA group did not (p = 0.087). For both medial and lateral UKA groups, the UKA limb demonstrated greater internal peak abductor moments (p = 0.005 and 0.013, respectively). Both UKA groups exhibited knee moments similar to those in the literature. Limb dominance and postoperative time were correlated for both UKA groups.
  
  
  CONCLUSIONS
  Reduced knee extensor moments of limbs with UKA displayed by some participants may indicate less compressive loading on the tibiofemoral joint surfaces, whereas the increased abductor moments suggest increased compression on the medial compartment. These findings suggest UKA knees may not be subjected to excessive loads regardless of the side reconstructed.
authors.affiliation: Department of Health, Exercise Science, & Recreation Management, University of Mississippi, Oxford, MS, USA.
authors.forename: Yang-Chieh
authors.initials: YC
authors.lastname: Fu
authors.forename: Kathy J
authors.initials: KJ
authors.lastname: Simpson
authors.forename: Cathleen
authors.initials: C
authors.lastname: Brown
authors.forename: Tracy L
authors.initials: TL
authors.lastname: Kinsey
authors.forename: Ormonde M
authors.initials: OM
authors.lastname: Mahoney
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D001696:Biomechanical Phenomena / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007717:Knee / Q000502:physiology* / Q000601:surgery; D007719:Knee Joint / Q000502:physiology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000503:physiopathology* / Q000601:surgery; D016059:Range of Motion, Articular / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology*; D016896:Treatment Outcome