title: Alterations in knee kinematics after partial medial meniscectomy are activity dependent.
abstract: BACKGROUND
  Alterations in knee kinematics after partial meniscectomy have been linked to the increased risk of osteoarthritis in this population. Understanding differences in kinematics during static versus dynamic activities of increased demand can provide important information regarding the possible underlying mechanisms of these alterations.
  
  
  OBJECTIVE
  Differences in the following 2 kinematics measures will increase with activity demand: (1) the offset toward external tibial rotation for the meniscectomized limb compared with the contralateral limb during stance and (2) the difference in knee flexion angle at initial foot contact between the meniscectomized and contralateral limbs.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  This study compared side-to-side differences in knee flexion and rotation angles during static and dynamic activities. Thirteen patients (2 female) were tested in a motion capture laboratory at 6 ± 2 months after unilateral, arthroscopic, partial medial meniscectomy during a static reference pose and during 3 dynamic activities: walking, stair ascent, and stair descent.
  
  
  RESULTS
  The meniscectomized limb demonstrated more external tibial rotation compared with the contralateral limb during dynamic activities, and there was a trend that this offset increased with activity demand (repeated-measures analysis of variance [ANOVA] for activity, P = .07; mean limb difference: static pose, -0.1° ± 3.3°, P = .5; walking, 1.2° ± 3.8°, P = .1; stair ascent, 2.0° ± 3.2°, P = .02; stair descent, 3.0° ± 3.5°, P = .005). Similarly, the meniscectomized knee was more flexed at initial contact than the contralateral limb during dynamic activities (repeated-measures ANOVA for activity P = .006; mean limb difference: reference pose, 1.0° ± 2.5°, P = .09; walking, 2.0° ± 3.9°, P = .05; stair ascent, 5.9° ± 5.3°, P = .009; stair descent, 3.5° ± 4.0°, P = .004).
  
  
  CONCLUSIONS
  These results suggest both a structural element and a potential muscular element for the differences in kinematics after partial medial meniscectomy and highlight the importance of challenging the knee with activities of increased demands to detect differences in kinematics from the contralateral limb.
  
  
  CONCLUSIONS
  With further investigation, these findings could help guide clinical rehabilitation of patients with torn meniscus tissue, especially in the context of the patients' increased risk of joint degeneration.
authors.affiliation: Department of Mechanical Engineering, Stanford University, Stanford, California, USA VA Palo Alto, Palo Alto, California, USA snedd@stanford.edu.
authors.forename: Shannon N
authors.initials: SN
authors.lastname: Edd
authors.affiliation: Department of Mechanical Engineering, Stanford University, Stanford, California, USA VA Palo Alto, Palo Alto, California, USA.
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Netravali
authors.affiliation: Department of Mechanical Engineering, Stanford University, Stanford, California, USA.
authors.forename: Julien
authors.initials: J
authors.lastname: Favre
authors.affiliation: VA Palo Alto, Palo Alto, California, USA Department of Orthopaedic Surgery, Stanford University Medical Center, Stanford, California, USA.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Giori
authors.affiliation: Department of Mechanical Engineering, Stanford University, Stanford, California, USA VA Palo Alto, Palo Alto, California, USA Department of Orthopaedic Surgery, Stanford University Medical Center, Stanford, California, USA.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Andriacchi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001182:Arthroscopy / Q000379:methods; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005260:Female; D005684:Gait; D006801:Humans; D007718:Knee Injuries / Q000503:physiopathology* / Q000601:surgery; D007719:Knee Joint / Q000503:physiopathology; D008297:Male; D008592:Menisci, Tibial / Q000503:physiopathology / Q000601:surgery; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology; D012399:Rotation; D013977:Tibia / Q000502:physiology; D000070600:Tibial Meniscus Injuries; D016138:Walking / Q000502:physiology; D055815:Young Adult
keywords: biomechanics; gait analysis; meniscus; osteoarthritis; stairs; walking