title: Patella bone density is lower in knee osteoarthritis patients experiencing moderate-to-severe pain at rest.
abstract: OBJECTIVE
  To determine differences in patellar subchondral bone mineral density (BMD) between knee osteoarthritis (OA) patients with differing levels of pain at rest.
  
  
  METHODS
  The preoperative knee of 41 total knee replacement (TKR) patients was scanned using QCT and scored for pain using Western Ontario McMasters Osteoarthritis Index (WOMAC). 'Pain at rest' was defined as average pain while lying//sitting and nocturnal pain. Participants were divided into groups: 'mild-to-no pain at rest' and 'moderate-to-severe pain at rest'. We used a depth-specific CT-based mapping technique to measure patellar subchondral BMD at depths of 0-2.5 mm, 2.5-5 mm, and 5-7.5 mm from the subchondral surface. Mean lateral and medial facet BMD were compared between groups using MANCOVA.
  
  
  RESULTS
  Mean adjusted BMD was lower in participants with 'moderate-to-severe pain at rest' over the total lateral facet at depths of 0-2.5 mm (10% lower, p=0.041), 2.5-5 mm (20% lower, p=0.017), and 5-7.5 mm (25% lower, p=0.004), and over the total medial facet at 2.5-5 mm (22% lower, p=0.033) and 5-7.5 mm (28% lower, p=0.016).
  
  
  CONCLUSIONS
  In OA patients with 'moderate-to-severe pain at rest', depth-specific density measures demonstrated up to 28% lower lateral and medial subchondral BMD. Patients with high levels of pain at rest may have reduced amounts of native bone prior to TKR.
authors.affiliation: University of Saskatchewan, Division of Biomedical Engineering.
authors.forename: W
authors.initials: W
authors.lastname: Burnett
authors.forename: S
authors.initials: S
authors.lastname: Kontulainen
authors.forename: C
authors.initials: C
authors.lastname: McLennan
authors.forename: D
authors.initials: D
authors.lastname: Hazel
authors.forename: C
authors.initials: C
authors.lastname: Talmo
authors.forename: D
authors.initials: D
authors.lastname: Hunter
authors.forename: D
authors.initials: D
authors.lastname: Wilson
authors.forename: J
authors.initials: J
authors.lastname: Johnston
mesh_terms: D000368:Aged; D015519:Bone Density; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications* / Q000000981:diagnostic imaging*; D010146:Pain / Q000209:etiology*; D010329:Patella / Q000473:pathology*; D012146:Rest; D014057:Tomography, X-Ray Computed