title: Femoral tunnel length in primary anterior cruciate ligament reconstruction using an accessory medial portal.
abstract: OBJECTIVE
  The purpose of this study was to evaluate tunnel length during independent femoral tunnel drilling using an accessory medial portal with the knee in maximal hyperflexion, and correlate the tunnel length and flexion angle with anthropometric data.
  
  
  METHODS
  During a 1-year period, 106 consecutive patients undergoing primary anterior cruciate ligament (ACL) reconstruction were included in the study. All patients underwent independent femoral tunnel drilling using an accessory medial portal with maximal knee hyperflexion. Tunnel length and maximal intraoperative knee flexion angles were measured. Additionally, height, weight, and body mass index (BMI), plus the width and depth of the lateral femoral condyle (LFC), were recorded to correlate with tunnel length and knee flexion angles.
  
  
  RESULTS
  Average tunnel length was 37.0 ± 3.3 mm (range, 26 to 45), with all but one tunnel greater than 30 mm. Average knee flexion angle was 134.4 ± 5.0° (range, 122° to 147°). Height (r = 0.5, P < .001) and weight (r = 0.33, P = .001), but not BMI (r = 0.14, P = .17), correlated positively with tunnel length. Width (r = 0.46, P < .001) and depth (r = 0.38, P < .001) of the LFC also correlated positively with tunnel length. Knee flexion angle was not correlated with tunnel length (r = -0.09, P = .39) or width (r = -0.04, P = .7) and depth (r = -0.01, P = .91) of the LFC. Knee flexion angle was negatively correlated with weight (r = -0.44, P < .001) and BMI (r = -0.46, P < .001).
  
  
  CONCLUSIONS
  Using an accessory medial portal for independent femoral tunnel drilling, with maximal knee hyperflexion, in ACL reconstruction consistently produced tunnel lengths greater than 30 mm with no posterior wall fractures. Tunnel lengths tend to be longer with increasing patient height, mass, and larger LFC dimensions. Maximum knee flexion angle achieved intraoperatively tends to be less for patients with increasing weight and BMI.
  
  
  METHODS
  Level IV, therapeutic case series.
authors.affiliation: Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, Minnesota 55454, USA. tompkinsm@hotmail.com
authors.forename: Marc
authors.initials: M
authors.lastname: Tompkins
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Milewski
authors.forename: Eric W
authors.initials: EW
authors.lastname: Carson
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Brockmeier
authors.forename: Joshua C
authors.initials: JC
authors.lastname: Hamann
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Hart
authors.forename: Mark D
authors.initials: MD
authors.lastname: Miller
mesh_terms: D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction / Q000295:instrumentation*; D001182:Arthroscopy; D005260:Female; D005269:Femur / Q000601:surgery*; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D008297:Male; D055815:Young Adult