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Journal Title
Title of Journal: Knee Surg Sports Traumatol Arthrosc
Abbravation: Knee Surgery, Sports Traumatology, Arthroscopy
Publisher
Springer-Verlag
DOI
10.1016/0042-207x(64)92191-8
ISSN
1433-7347
This study was done to determine whether there is a correlation between the notch volume and the notch width index NWI as measured on the three most frequently used radiographic views the Holmblad 45° Holmblad 70° and Rosenberg view The notch volume of 20 cadaveric knees was measured using Computed Tomography CT The Holmblad 45° Holmblad 70° and Rosenberg notch view radiographs were digitally recreated from the CT scans for each specimen and the NWI was measured by two observers The Pearson correlation coefficient between the NWI and notch volume was calculated as well as between the three views An independent t test was performed to determine the difference in NWI and notch volume between male and female specimens The reliability for each view was also determined There was no correlation between the NWI as measured on the Holmblad 45° Holmblad 70° or Rosenberg view and the notch volume All three radiographic views proved reliable but showed only a moderate correlation with each other Men had larger notch volumes than women but there was no difference in NWI A knee with a small intercondylar notch is often considered an increased risk for ACL rupture The NWI is a frequently used twodimensional method to determine notch size However in the present study this index was not positively correlated with the overall volume of the notch Based on the results of the current study the authors would advice to use caution when using notch view radiographs in a clinical setting to predict risk of ACL ruptureThe close relationship between the function of the anterior cruciate ligament ACL and the femoral intercondylar notch has long been recognized 10 The most widely used twodimensional measurement of the notch size is the notch width index NWI This method was described by Souryal and Freeman in 1988 and is defined as the width of the intercondylar notch at the level of the popliteal groove divided by the bicondylar width at the same level 13 This is measured on a notch view radiograph with the knee in 45° of flexion After the NWI was established many different notch view radiographic methods have been proposed to visualize the anterior and posterior outlet of the notch and the popliteal groove the Holmblad 45° view 7 the Holmblad 70° view 8 12 and the Rosenberg view 6 11 The accuracy of these methods was recently studied by Anderson et al who compared the radiographic measurements to caliper measurements in cadaveric specimens and concluded that only the Holmblad 70° view was accurate 1 However to our knowledge there has not been any study to determine which if any radiographic view best predicts overall notch size ie volumeWe also had three secondary aims The first was to determine the intra and interobserver reliability of the three views The second to determine the correlation between the three NWIs as measured on the Holmblad 45° Holmblad 70° and Rosenberg view Lastly we aimed to determine whether there was a difference in NWI and notch volume between male and female specimensThe notch area was measured on all axial CT slices that contained the notch The green outline illustrates the notch area and the box provides information about the size Subsequently all the areas were summated and multiplied by the slice thickness to determine the notch volume This is a simplified image since an average notch would contain between 30 and 100 slices depending on the extent of the notchThis image illustrates how the Amira software reconstructs a digital radiograph using a threedimensional reconstruction of the CT scan a The threedimensional reconstruction of the CT scan of the knee is made and a digital radiograph is made through this reconstruction and projected on the background b The femur is rotated to simulate the position to the Xray source according to the three different notch view techniques The tibia is partially removed to eliminate overprojection and improve image quality of the simulated radiograph C The reconstructed CT scan is removed and the notch view radiograph is visible on the bottom This notch view radiograph can be saved as a separate image and subsequently measured with ImageJ software