title: Sex Differences and Impact of Body Mass Index on the Time Course of Knee Range of Motion, Knee Strength, and Gait Speed After Total Knee Arthroplasty.
abstract: OBJECTIVE
  Quadriceps strength deficits and gait speed limitations remain significant issues after total knee arthroplasty (TKA), yet detailed longitudinal data characterizing these measures and their predictors are limited. This study aimed to describe the time course of knee range of motion, quadriceps strength, and gait speed post-TKA, and to assess whether sex and body mass index (BMI) influenced the time recovery of these measures.
  
  
  METHODS
  A total of 1,025 patients (mean ± SD age 67 ± 8 years) undergoing primary TKA participated. At 4-, 8-, 12-, and 16-weeks postsurgery, knee range of motion, quadriceps strength, and gait speed were quantified. The associations of the knee and gait measures profile over time with sex and BMI were assessed using generalized least squares modeling.
  
  
  RESULTS
  The various knee and gait measures improved nonlinearly over time, with substantial improvements observed in the first 8-10 weeks postsurgery. Sex and BMI influenced the time course of quadriceps strength (P < 0.001 for all interactions): improvements in quadriceps strength over time were slower in women and in patients with higher BMI. Post-TKA gait speed was consistently lower in women than in men, while BMI was negatively and nonlinearly related to gait speed.
  
  
  CONCLUSIONS
  Although the various knee and gait measures improved over time, women and patients with higher BMI had poorer functional outcomes. The present study highlights the need for a mechanistic understanding of the results and targeted management of these patient subgroups.
authors.affiliation: Singapore General Hospital, Singapore.
authors.forename: Yong-Hao
authors.initials: YH
authors.lastname: Pua
authors.affiliation: Singapore General Hospital, Singapore.
authors.forename: Felicia Jie-Ting
authors.initials: FJ
authors.lastname: Seah
authors.affiliation: Singapore General Hospital, Singapore.
authors.forename: Felicia Jia-Hui
authors.initials: FJ
authors.lastname: Seet
authors.affiliation: Singapore General Hospital, Singapore.
authors.forename: John Wei-Ming
authors.initials: JW
authors.lastname: Tan
authors.affiliation: Singapore General Hospital, Singapore.
authors.forename: Jennifer Suet-Ching
authors.initials: JS
authors.lastname: Liaw
authors.affiliation: Singapore General Hospital, Singapore.
authors.forename: Hwei-Chi
authors.initials: HC
authors.lastname: Chong
mesh_terms: D000054:Acceleration; D000368:Aged; D053587:Arthrometry, Articular; D019645:Arthroplasty, Replacement, Knee / Q000379:methods / Q000534:rehabilitation*; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000601:surgery; D011182:Postoperative Care / Q000379:methods; D011379:Prognosis; D052097:Quadriceps Muscle / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology*; D020127:Recovery of Function; D018570:Risk Assessment; D012720:Severity of Illness Index; D012846:Singapore; D013997:Time Factors; D016896:Treatment Outcome