title: Abnormal Patella Height Based on Insall-Salvati Ratio and its Correlation with Patellar Cartilage Lesions: An Extremity-Dedicated Low-Field Magnetic Resonance Imaging Analysis of 1703 Chinese Cases.
abstract: OBJECTIVE
  Diagnostic performance of patellar position for patellar cartilage lesions remains unclear. The aim of this study was to assess the abnormal patella height and its correlation with chondral lesions of the patellofemoral joint in China.
  
  
  METHODS
  A total of 1703 consecutive patients who performed knee joint examination using an extremity-dedicated low-field magnetic resonance imaging were enrolled in this study. Patellar cartilage lesions were diagnosed based on the result of magnetic resonance imaging and clinical data. Patella height was defined as the ratio of patellar tendon length to patellar length according to Insall-Salvati index. Patella alta and infera were defined as tendon length/patellar length >1.2 and <0.8, respectively.
  
  
  RESULTS
  The total prevalence of patellar cartilage lesions was 38.0%. The prevalence in females was significantly higher than that in males (46.4% vs 28.8%, p < 0.001). Age notably increased the incidence of patellar cartilage lesions (p < 0.001). Logistic regression analysis showed that tendon length/patellar length ratio was significantly correlated with patellar cartilage lesions (odds ratio = 6.380, p < 0.001). Furthermore, patients with cartilage lesions showed significantly higher rates of patella alta and infera (p < 0.001). In addition, receiver operating characteristic curve analysis demonstrated that abnormal patella height had statistical significance in diagnosing cartilage lesions (p < 0.001). However, the area under the curve (0.596; 95% confidence interval: 0.568-0.624) and sensitivity (47.0%) were relatively low, while the specificity was 72.2%.
  
  
  CONCLUSIONS
  Patients with patellar cartilage lesions have an increased tendon length/patellar length ratio. The abnormal patella height is significantly correlated with chondral lesions and can be used as a potential diagnostic marker.
authors.affiliation: Department of Radiology, Tongren Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: W
authors.initials: W
authors.lastname: Lu
authors.affiliation: Department of Radiology, Tongren Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China junyangjjyy@163.com.
authors.forename: J
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Radiology, Huashan Hospital Affiliated to Shanghai Fudan University School of Medicine, Shanghai, China.
authors.forename: S
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Radiology, Tongren Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Department of Radiology, Tongren Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: C
authors.initials: C
authors.lastname: Zhu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000293:injuries*; D002648:Child; D002681:China; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000000981:diagnostic imaging / Q000209:etiology*; D016015:Logistic Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010329:Patella / Q000002:abnormalities* / Q000000981:diagnostic imaging; D057071:Patellofemoral Joint / Q000000981:diagnostic imaging / Q000293:injuries*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D055815:Young Adult
keywords: Chondral lesions; diagnostic accuracy; magnetic resonance imaging; patella alta; patella infera; patellofemoral joint