title: [Relationship between anatomy of knee collateral ligament and geometry of posterior femoral condylar articular surface].
abstract: OBJECTIVE
  To analyze the relationship between the collateral ligament attachment and the epicondylar axis with rotational alignment of the femoral component in the total knee arthroplasty(TKA).
  
  
  METHODS
  Twenty normal cadaver knee joints were anatomized and 2 holes were drilled on the distal femur from the deep and superficial insertions of the medial collateral ligaments to the lateral condylar part, respectively. Then, all the knees were scanned by MRI on the sagittal plane, making the drilled hole located relatively to the posterior condylar joint surface on the axial plane, and the posterior condylar angle (PCA) and the condylar twist angle (CTA) were measured.
  
  
  RESULTS
  The collateral ligament had the deep and superficial parts, and the deep part was strained during the knee flexing. PCA and CTA were 4.50 +/- 1.26 degrees and 7.10 +/- 0.30 degrees respectively, and there was a significant difference between them (P < 0.05), which were significantly greater than those reported abroad. On the sagittal plane, there was no significant difference between the radius of the posterior medial and lateral condylar circles (P > 0.05). The distance from the center of the posterior condylar circle to the deep insertion of the medial collateral ligament (MCL) (dl) was 4.22 +/- 0.20 mm, and the distance to the superficial insertion of MCL (d2) was 7.36 +/- 0.13 mm. The difference between dl and d2 was significant (P < 0.05).
  
  
  CONCLUSIONS
  The center of the posterior condylar circle passes from the deep insertion of the collateral ligament, which can be regarded as a fixed flexion-extension axis of the knee. By releasing the different parts of the collateral ligaments, the balance of the flexion and extension gap can be obtained, and then varus, valgus or flexed contracture deformity of the knee can be realigned. Besides, the rotational orientation of the femoral prosthesis can be made by a reference to the epicondylar insertion of the collateral ligament.
authors.affiliation: Arthritis Clinic & Research Center, Peking University People's Hospital, Beijing, 100044, PR China. zhoudiange@medmail.com.cn
authors.forename: Diange
authors.initials: D
authors.lastname: Zhou
authors.forename: Houshan
authors.initials: H
authors.lastname: Lv
authors.forename: Jing
authors.initials: J
authors.lastname: Fang
mesh_terms: D000328:Adult; D019645:Arthroplasty, Replacement, Knee; D006801:Humans; D007719:Knee Joint; D007720:Knee Prosthesis; D017888:Medial Collateral Ligament, Knee / Q000033:anatomy & histology*; D016059:Range of Motion, Articular