title: Patients with Osteoarthritis in all Three Knee Compartments and Patients with Medial Knee Osteoarthritis Have a Phenotype with High Bone Mass and High Fat Mass but Proportionally Low Lean Mass.
abstract: OBJECTIVE
  Cross-sectional studies have shown that patients with primary hip osteoarthritis (OA) have higher bone mineral density (BMD), higher BMI, lower lean body mass, and higher fat content. But it is unknown if this phenotype is found also in patients with knee OA and if it precedes OA or manifests as a result of the disease.
  
  
  METHODS
  We included 21 women and 18 men (mean age, 71 years; range, 48-85 years) with primary OA in all three knee compartments, 17 women and 56 men (mean age, 55 years; range, 34-74 years) with primary medial knee OA and 122 women and 121 men without OA as controls. We measured total body BMD (g/cm(2)), fat and lean mass (%) by dual energy X-ray absorptiometry and also registered height and weight to calculate BMI (kg/m(2)). Z-scores were calculated for each individual. Data are presented as means with 95% confidence intervals within brackets.
  
  
  RESULTS
  Individuals with primary OA in all three knee compartments had the following Z-scores: total body BMD 0.4 (0.0, 0.9); BMI 1.2 (0.7, 1.6); proportion of lean mass -0.6 (-1.1, -0.1); proportion of fat mass 0.4 (0.0, 1.8). Individuals with medial knee OA had the following Z-scores: total body BMD 0.4 (0.3, 0.6); BMI 1.1 (0.8, 1.4); proportion of lean mass -0.8 (-1.3, -0.9); proportion of fat mass 0.9 (0.7, 1.1).
  
  
  CONCLUSIONS
  A phenotype with higher BMD, higher BMI, higher fat mass, and proportionally lower lean body mass is evident in individuals with primary OA in all three knee compartments and in patients with only medial knee OA.
authors.affiliation: Department of Orthopedics, Skåne University Hospital, SE-205 02 Malmö, Sweden.
authors.forename: Magnus K
authors.initials: MK
authors.lastname: Karlsson
authors.affiliation: Department of Orthopedics, Skåne University Hospital, SE-205 02 Malmö, Sweden.
authors.forename: Håkan
authors.initials: H
authors.lastname: Magnusson
authors.affiliation: Department of Orthopedics, Skåne University Hospital, SE-205 02 Malmö, Sweden.
authors.forename: Thord
authors.initials: T
authors.lastname: von Schewelov
authors.affiliation: Department of Orthopedics, Skåne University Hospital, SE-205 02 Malmö, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Cöster
authors.affiliation: Department of Orthopedics, Skåne University Hospital, SE-205 02 Malmö, Sweden.
authors.forename: Caroline
authors.initials: C
authors.lastname: Karlsson
authors.affiliation: Department of Orthopedics, Skåne University Hospital, SE-205 02 Malmö, Sweden.
authors.forename: Björn E
authors.initials: BE
authors.lastname: Rosengren
keywords: Generalized; knee; localized; men; osteoarthritis; women.