title: Muscle activity around the knee and gait performance in unicompartmental knee arthroplasty patients: a comparative study on fixed- and mobile-bearing designs.
abstract: OBJECTIVE
  Unicompartmental knee arthroplasty (UKA) offers clinical and functional advantages over total knee arthroplasty. The aim of this study was to compare the functional recovery of patients with mobile UKA versus fixed-bearing designs by state-of-the-art gait analysis and, in particular, by assessing muscular activity.
  
  
  METHODS
  Ten patients with the Oxford (mobile bearing) and ten patients with Optetrak (fixed bearing) UKA were evaluated at a minimum follow-up of 1 year post-operatively by gait analysis, which includes the main time-distance parameters, kinematics and kinetics of the replaced knee, and muscular activity of the main relevant muscles. Twenty healthy young subjects were used as controls.
  
  
  RESULTS
  The mean International Knee Society score was 92.7 ± 11.2 for all 20 UKA knees; for the Oxford UKA, it was 94.1 ± 9.5; and for the Optetrak UKA, it was 91.5 ± 12.9, although follow-up was significantly lower for the latter. Time-distance parameters showed a slower gait in both groups compared with that of controls, and the Oxford group had values closer to the controls. Knee joint flexion was similar to that of controls at initial contact and loading response with no differences between groups. In all patients, the joint moments were smaller to that of controls. Residual abnormalities such as the prolonged rectus femoris activity were present in both designs, and the only difference distinguishing the Optetrak group from the others was the combined co-contraction of the hamstrings.
  
  
  CONCLUSIONS
  A good restoration of gait was achieved by most unicompartmental knee patients independently of the UKA design, although some abnormalities persisted in muscle activity around the knee.
  
  
  METHODS
  Retrospective comparative study, Level III.
authors.affiliation: Department of Orthopaedic Surgery, Rizzoli Orthopedic Institute, University of Bologna, Bologna, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Catani
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Benedetti
authors.forename: Luca
authors.initials: L
authors.lastname: Bianchi
authors.forename: Valentina
authors.initials: V
authors.lastname: Marchionni
authors.forename: Sandro
authors.initials: S
authors.lastname: Giannini
authors.forename: Alberto
authors.initials: A
authors.lastname: Leardini
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods / Q000534:rehabilitation; D060751:Bone Retroversion / Q000601:surgery; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D005684:Gait / Q000502:physiology*; D006305:Health Status Indicators; D006801:Humans; D007717:Knee / Q000502:physiology*; D007719:Knee Joint / Q000502:physiology*; D007720:Knee Prosthesis; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D020370:Osteoarthritis, Knee / Q000601:surgery; D010020:Osteonecrosis / Q000601:surgery; D020127:Recovery of Function / Q000502:physiology*; D012189:Retrospective Studies; D012399:Rotation; D016896:Treatment Outcome