title: Association between patella alta and the prevalence and worsening of structural features of patellofemoral joint osteoarthritis: the multicenter osteoarthritis study.
abstract: OBJECTIVE
  To examine the relationship between patella alta and the prevalence and worsening at followup of structural features of patellofemoral joint (PFJ) osteoarthritis (OA) on magnetic resonance imaging (MRI).
  
  
  METHODS
  The Multicenter Osteoarthritis Study is a cohort study of persons ages 50-79 years with or at risk for knee OA. Patella alta was measured using the Insall-Salvati ratio (ISR) on the baseline lateral radiograph, and cartilage damage, bone marrow lesions (BMLs), and subchondral bone attrition (SBA) were graded on MRI at baseline and at 30 months of followup in the PFJ. We examined the association of the ISR with the prevalence and worsening of cartilage damage, BMLs, and SBA in the PFJ using logistic regression.
  
  
  RESULTS
  A total of 907 knees were studied (mean age 62 years, body mass index 30 kg/m(2), ISR 1.10), 63% from female subjects. Compared with knees in the lowest ISR quartile at baseline, those in the highest quartile had 2.4 (95% confidence interval [95% CI] 1.7-3.3), 2.9 (95% CI 2.0-4.3), and 3.5 (95% CI 2.3-5.5) times the odds of having lateral PFJ cartilage damage, BMLs, and SBA, respectively, and 1.5 (95% CI 1.1-2.0), 1.3 (95% CI 0.9-1.8), and 2.2 (95% CI 1.4-3.4) times the odds of having medial PFJ cartilage damage, BMLs, and SBA, respectively. Similarly, those with high ISRs were also at risk for worsening of cartilage damage and BMLs over time than those with low ISRs.
  
  
  CONCLUSIONS
  A high ISR, indicative of patella alta, is associated with structural features of OA in the PFJ. Additionally, the same knees have an increased risk of worsening of these same features over time.
authors.affiliation: Boston University School of Medicine, Boston, Massachusetts 02118, USA. stefanik@bu.edu
authors.forename: J J
authors.initials: JJ
authors.lastname: Stefanik
authors.forename: Y
authors.initials: Y
authors.lastname: Zhu
authors.forename: A C
authors.initials: AC
authors.lastname: Zumwalt
authors.forename: K D
authors.initials: KD
authors.lastname: Gross
authors.forename: M
authors.initials: M
authors.lastname: Clancy
authors.forename: J A
authors.initials: JA
authors.lastname: Lynch
authors.forename: L A
authors.initials: LA
authors.lastname: Frey Law
authors.forename: C E
authors.initials: CE
authors.lastname: Lewis
authors.forename: F W
authors.initials: FW
authors.lastname: Roemer
authors.forename: C M
authors.initials: CM
authors.lastname: Powers
authors.forename: A
authors.initials: A
authors.lastname: Guermazi
authors.forename: D T
authors.initials: DT
authors.lastname: Felson
mesh_terms: D000368:Aged; D000886:Anthropometry; D001696:Biomechanical Phenomena; D015519:Bone Density; D001853:Bone Marrow / Q000000981:diagnostic imaging / Q000473:pathology; D001855:Bone Marrow Diseases / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology; D001862:Bone Resorption / Q000150:complications / Q000209:etiology / Q000473:pathology; D002357:Cartilage Diseases / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology; D002358:Cartilage, Articular / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000473:pathology; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology; D007719:Knee Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000473:pathology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010329:Patella / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000473:pathology; D057071:Patellofemoral Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000473:pathology*; D011859:Radiography; D012307:Risk Factors; D013314:Stress, Mechanical