title: Is there a dose response for valgus unloader brace usage on knee pain, function, and muscle strength?
abstract: OBJECTIVE
  To examine whether there was a dose response for valgus unloader brace wear on knee pain, function, and muscle strength in participants with medial compartment knee osteoarthritis.
  
  
  METHODS
  In this single-group study, participants with medial compartment knee osteoarthritis were followed for approximately 6 months.
  
  
  METHODS
  Recruitment was conducted in the general community, and testing was performed at a university laboratory.
  
  
  METHODS
  A convenience sample of patients (N=32) who were prescribed a valgus unloader brace agreed to participate, met the inclusion criteria, and completed the baseline data collection. Twenty-four participants (20 men, 4 women) completed baseline and follow-up collections.
  
  
  METHODS
  Participants wore their valgus unloader brace as needed.
  
  
  METHODS
  Knee extensor, flexor, and plantar flexor strength was tested at baseline and follow-up. Participants filled out Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Medical Outcomes Study 36-Item Short-Form Health Survey questionnaires to assess pain and function. Self-selected walking velocity and stride length were objective measures of function. Brace usage (dose) and activity (step count) were recorded at least 4 days/week for the study duration.
  
  
  RESULTS
  Positive relationships existed between brace wear usage and percent change in step count (r=.59, P=.006) and percent change in hamstrings strength (r=.37, P=.072). At follow-up, there was significant improvement in hamstrings strength (P=.013), and trends toward improvements in WOMAC pain (P=.059) and WOMAC function (P=.089).
  
  
  CONCLUSIONS
  Our results indicate that greater brace use may positively affect physical activity level, but there was minimal effect of brace wear dosage on lower-limb muscle strength. Only knee flexion showed a positive relationship. Our finding of no decreased muscle strength indicates that increased brace use over a 6-month period does not result in muscle impairment.
authors.affiliation: School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada.
authors.forename: Sean T
authors.initials: ST
authors.lastname: Hurley
authors.forename: Gillian L
authors.initials: GL
authors.lastname: Hatfield Murdock
authors.forename: William D
authors.initials: WD
authors.lastname: Stanish
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Hubley-Kozey
mesh_terms: D000368:Aged; D015992:Body Mass Index; D001915:Braces; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D020370:Osteoarthritis, Knee / Q000150:complications / Q000534:rehabilitation*; D010146:Pain / Q000209:etiology / Q000534:rehabilitation*; D013997:Time Factors