title: Transtibial versus anteromedial portal technique in single-bundle anterior cruciate ligament reconstruction: outcomes of knee joint kinematics during walking.
abstract: BACKGROUND
  In anterior cruciate ligament (ACL) reconstruction, the transtibial (TT) technique often creates a nonanatomically placed femoral tunnel, which is a frequent cause of surgical failure and postsurgical knee instability. Several studies reported that drilling the femoral tunnel through an anteromedial portal (AMP) yields a more anatomic tunnel position compared with the TT technique.
  
  
  OBJECTIVE
  To compare the effectiveness of these two surgical techniques in restoring the intact knee joint kinematics during a physiological loading situation.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Twenty-four patients (TT, n = 12; AMP, n = 12; sex, weight, and height matched, and half with dominant leg involved) who underwent unilateral single-bundle ACL reconstruction by the same surgeon were recruited. Twenty healthy patients with no history of lower limb injuries were recruited as the control group. Tibiofemoral joint motion in 6 degrees of freedom (3 translations and 3 rotations) was determined during level walking by using a least mean square-based optimization algorithm. A redundant marker set was used to improve the accuracy of the motion analysis. Knee joint kinematics as well as spatiotemporal parameters were compared between these two techniques.
  
  
  RESULTS
  The AMP technique restored the anterior-posterior translation of the knee joint, while the TT technique resulted in significantly greater (TT, 22.2 mm vs controls, 13.2 mm; P < .01) anterior femoral translations than in the healthy controls during the swing phase. Excessive femoral external (tibial internal) rotation (3.8°; P < .05) was found at midstance in the knees that were reconstructed using the TT technique; using the AMP technique, the external rotation offset was greatly reduced during the stance phase. However, knees repaired using the AMP technique were significantly less extended (5°; P < .05) compared with the knees of the controls during the late stance phase. Neither surgical technique restored the superior-inferior femoral translation to the intact level during the swing phase.
  
  
  CONCLUSIONS
  The AMP technique better restores the anterior-posterior translation during the swing phase and femoral external rotation at midstance than the TT technique does. However, the AMP technique is also correlated with an extension loss during the late stance phase.
  
  
  CONCLUSIONS
  The AMP femoral tunnel drilling technique can improve overall knee joint stability, but the increased difficulty with full extension may need to be considered.
authors.affiliation: Department of Mechanical Engineering and Engineering Science, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223, USA.
authors.forename: Hongsheng
authors.initials: H
authors.lastname: Wang
authors.forename: James E
authors.initials: JE
authors.lastname: Fleischli
authors.forename: Naiquan Nigel
authors.initials: NN
authors.lastname: Zheng
mesh_terms: D000328:Adult; D000465:Algorithms; D000704:Analysis of Variance; D016118:Anterior Cruciate Ligament / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D005684:Gait / Q000502:physiology*; D006801:Humans; D007718:Knee Injuries / Q000601:surgery*; D007719:Knee Joint / Q000502:physiology* / Q000601:surgery; D016018:Least-Squares Analysis; D008297:Male; D016059:Range of Motion, Articular; D016896:Treatment Outcome; D016474:Weight-Bearing
keywords: ACL reconstruction; extension difficulty; gait analysis; osteoarthritis; tibial rotation; transportal