title: Radiographical definition of the proximal tibiofibular joint - A cross-sectional study of 2984 knees and literature review.
abstract: BACKGROUND
  Proximal tibiofibular joint (PTFJ) injuries are not uncommon but relatively understudied. This study evaluates the effectiveness of 2 radiographic methods in assessing the integrity of the PTFJ.
  
  
  METHODS
  This is a cross-sectional study of 2984 consecutive patients with knee X-rays done in a single institution over a 4-month period. A total of 5968 knee X-rays were assessed using 2 methods-[1] The direction in which the fibula points to in relation to the lateral femoral epicondyle on anteroposterior view and Blumensaat line on lateral view. [2] The degree of tibiofibular overlap as percentage of widest portion of the fibula head. Sensitivity and specificity of these methods in diagnosing a disrupted PTFJ are calculated. Variables including quality of X-rays, weight-bearing status of AP views and degree of knee flexion on lateral views are also recorded. Univariate analysis was carried out to investigate the association between variables using chi-square test for nominal data and student t-test for continuous data.
  
  
  RESULTS
  The fibular points towards the lateral femoral epicondyle on AP view in 94.4% of the patients and points towards the posterior half of the Blumensaat line on lateral view in 98.1% of the patients. Using this method, weight-bearing X-rays are significantly associated with the direction the fibula is pointing (p<0.01) on the AP view and the degree of knee flexion is associated with the direction the fibula is pointing (p<0.01) on the lateral view. The AP tibiofibular overlap ranges from >0% to <75% in 94.1% of the patients and the lateral tibiofibular overlap ranges from >0% to <75% in 84.5% of the patients. This method is associated with whether true orthogonal X-rays of the knees are taken (p=0.048).
  
  
  CONCLUSIONS
  The direction in which the fibula is pointing and the percentage of tibiofibular overlap are highly specific radiographic methods useful in defining the PTFJ. The first method requires a weight-bearing view on AP assessment and >20 degrees of flexion on lateral assessment. True orthogonal AP and lateral views are required for the second method to be used.
authors.affiliation: Department of Orthopaedic Surgery National University Health System, Singapore. Electronic address: dennis_hey@nuhs.edu.sg.
authors.forename: Hwee Weng Dennis
authors.initials: HW
authors.lastname: Hey
authors.affiliation: Department of Orthopaedic Surgery National University Health System, Singapore.
authors.forename: Li Wen Nathaniel
authors.initials: LW
authors.lastname: Ng
authors.affiliation: Department of Orthopaedic Surgery National University Health System, Singapore.
authors.forename: Yau Hong
authors.initials: YH
authors.lastname: Ng
authors.affiliation: Department of Diagnostic Imaging National University Health System, Singapore.
authors.forename: Wei Zhong Jonathan
authors.initials: WZ
authors.lastname: Sng
authors.affiliation: Department of Orthopaedic Surgery National University Health System, Singapore.
authors.forename: Ruben
authors.initials: R
authors.lastname: Manohara
authors.affiliation: Department of Orthopaedic Surgery National University Health System, Singapore.
authors.forename: Joseph Shanthakumar
authors.initials: JS
authors.lastname: Thambiah
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D005360:Fibula / Q000000981:diagnostic imaging* / Q000293:injuries; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging* / Q000503:physiopathology; D007718:Knee Injuries / Q000000981:diagnostic imaging* / Q000503:physiopathology; D007719:Knee Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011859:Radiography; D016059:Range of Motion, Articular; D013977:Tibia / Q000000981:diagnostic imaging* / Q000293:injuries; D055815:Young Adult
keywords: Dislocation; Knee; Proximal tibiofibular joint; Radiographs; Subluxation