title: In vivo stability and clinical comparison of anterior cruciate ligament reconstruction using low or high femoral tunnel positions.
abstract: BACKGROUND
  Several biomechanical studies have supported placing the femoral tunnel at a low position (10 or 2 o'clock) to achieve anterior and rotational knee stabilities after anterior cruciate ligament (ACL) reconstruction. However, no firm consensus has been reached regarding the merits and demerits of ACL reconstruction using a low femoral tunnel versus a high femoral tunnel (11 or 1 o'clock).
  
  
  OBJECTIVE
  A low femoral tunnel position during ACL reconstruction provides better intraoperative stability (especially, rotational stability) and clinical outcomes than does a high femoral tunnel position.
  
  
  METHODS
  Cohort study; Level of evidence 2.
  
  
  METHODS
  Sixty-two patients who underwent ACL reconstruction were equally allocated to low and high femoral tunnel groups; 58 were followed up for a minimum of 2 years (29 in the each group). After reconstruction and using a navigation system, the authors compared intraoperative anterior, internal rotational, and external rotational stabilities at 0°, 30°, 60°, and 90° of knee flexion and compared clinical outcomes, including Lysholm knee scores, Tegner activity scores, Lachman and pivot-shift test findings, and radiographic stabilities at final follow-up visits.
  
  
  RESULTS
  The low group showed significantly better intraoperative internal rotational stability at 0° and 30° of flexion but not at other angles (60° and 90°). Intraoperatively, no significant intergroup differences were found for anterior and external rotational stabilities at any flexion angle. Furthermore, clinical outcomes, including Lysholm knee and Tegner activity scores, showed no significant differences between the 2 groups at final follow-up visits (P > .05), and Lachman and pivot-shift test stability results and radiological stability data obtained at final follow-up were not significantly different between the 2 groups (P > .05).
  
  
  CONCLUSIONS
  The low femoral tunnel group showed better internal rotational stability at time zero during ACL reconstruction but similar anterior and external rotational stabilities. No significant differences were observed between the 2 groups in terms of clinical outcomes and stabilities after a minimum follow-up of 2 years.
authors.affiliation: Department of Orthopaedics, Chonnam National University Hwasun Hospital, Jeonnam, South Korea.
authors.forename: Jong Keun
authors.initials: JK
authors.lastname: Seon
authors.forename: Sang Jin
authors.initials: SJ
authors.lastname: Park
authors.forename: Keun Bae
authors.initials: KB
authors.lastname: Lee
authors.forename: Hyoung Yeon
authors.initials: HY
authors.lastname: Seo
authors.forename: Myung Sun
authors.initials: MS
authors.lastname: Kim
authors.forename: Eun Kyoo
authors.initials: EK
authors.lastname: Song
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D015331:Cohort Studies; D005260:Female; D005269:Femur / Q000601:surgery*; D006801:Humans; D007593:Joint Instability / Q000601:surgery*; D008297:Male; D019637:Orthopedic Procedures / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult