title: Proposed Methods for Real-Time Measurement of Posterior Condylar Angle during TKA.
abstract: OBJECTIVE
  Conventional instruments are known to result in high numbers of outliers in restoring femoral component rotation primarily due to fixed degree of external rotation resection relative to the posterior condylar line (PCL). Outliers can be reduced by determining the patient specific posterior condylar angle (PCA) preoperatively or intraoperatively. There is a paucity of methods that can be used during surgery for determining the PCA. We propose two simple, real-time methods to determine the PCA and hence to measure the axial anatomical variation during surgery.
  
  
  METHODS
  The study was conducted using axial computed tomography (CT) scans of the knees of 26 patients. The commercial software K-PACS and our proposed two methods (trigonometric and protractor) were used to measure the angle between the transepicondylar axis and PCL, i.e., PCA. Statistical comparison between the mean angles obtained by K-PACS and our methods were done.
  
  
  RESULTS
  The three methods resulted in similar PCAs. The mean PCA measured by the three methods were similar. The mean PCA value measured by the K-PACS, trigonometric method and protractor method was 6.27° (range, 0° to 12°), 6.23° (range, 0° to 11.11°) and 6.31° (range, 0° to 12°), respectively. There were significant correlations between the K-PACS measured PCA and trigonometrically or protractor measured PCA.
  
  
  CONCLUSIONS
  Our novel, simple, easily reproducible, real-time and radiation-free PCA measurement methods obviate the need for preoperative CT scan for identification of patient specific PCA.
authors.affiliation: Department of Orthopedics, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Prateek
authors.initials: P
authors.lastname: Behera
authors.affiliation: Department of Orthopedics, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Devendra Kumar
authors.initials: DK
authors.lastname: Chouhan
authors.affiliation: Department of Radiodiagnosis, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Prakash
authors.affiliation: Department of Orthopedics, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Mandeep
authors.initials: M
authors.lastname: Dhillon
keywords: Arthroplasty; Knee; Osteoarthritis; Posterior condylar axis