title: Transtibial versus independent drilling techniques for anterior cruciate ligament reconstruction: a systematic review, meta-analysis, and meta-regression.
abstract: BACKGROUND
  While numerous cadaveric, in vivo, and clinical studies have compared transtibial and independent drilling of femoral tunnels during anterior cruciate ligament reconstruction, there is no evidence-based consensus on which technique affords the best outcome.
  
  
  OBJECTIVE
  There is no difference in clinical outcome between transtibial and independent drilling of femoral tunnels.
  
  
  METHODS
  Systematic review with meta-analysis and meta-regression.
  
  
  METHODS
  Cadaveric, in vivo, and clinical studies comparing transtibial and independent drilling techniques were systematically identified. A qualitative synthesis of nonrandomized studies and meta-analysis of randomized controlled trials (RCTs) were performed. In addition, a meta-regression analysis of RCTs that did not directly compare drilling techniques was performed.
  
  
  RESULTS
  A total of 49 studies were included in the qualitative review, and 15 were included in the meta-analysis; 22 studies were included in the meta-regression. In biomechanical studies, independent drilling placed the center of the femoral tunnel closer to the center of the femoral footprint (mean difference, 2.69 mm; 95% CI, 0.46-4.92; P < .00001). Independent drilling reduced anterior tibial translation with the Lachman examination (mean difference, 2.2 mm; 95% CI, 0.34-4.07; P = .02), 134 N of anterior load (mean difference, 1 mm; 95% CI, 0.29-1.71; P = .006), and simulated pivot shift (mean difference, 3.36 mm; 95% CI, 1.88-4.85; P < .00001). The meta-analysis showed improved Lysholm scores with independent drilling (mean difference, -0.62 points; 95% CI, -1.09 to -0.55; P = .009), although the clinical relevance of this small difference is questionable. There were no significant differences in International Knee Documentation Committee (IKDC) objective scores or Tegner scores between groups. With the meta-regression, there were no significant differences in failure rates or IKDC objective scores.
  
  
  CONCLUSIONS
  While there are biomechanical data suggesting improved knee stability and more anatomic graft placement with independent drilling, no significant clinical differences were found between the 2 techniques.
  
  
  CONCLUSIONS
  The current evidence shows that transtibial and independent drilling techniques have equivalent clinical outcomes at short-term to midterm follow-up. The long-term effects of subtle differences in tunnel position and postoperative knee kinematics should be further studied in dedicated, prospective cohort and randomized studies.
authors.affiliation: Jonathan C. Riboh, Division of Sports Medicine and Shoulder Surgery, Department of Orthopaedic Surgery, Duke University, 6002 Tahoe Drive, Durham, NC 27713. jonathan.riboh@duke.edu.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Riboh
authors.forename: Vic
authors.initials: V
authors.lastname: Hasselblad
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Godin
authors.forename: Richard C
authors.initials: RC
authors.lastname: Mather
mesh_terms: D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D001696:Biomechanical Phenomena; D005269:Femur / Q000601:surgery; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D012044:Regression Analysis; D013977:Tibia / Q000601:surgery
keywords: anteromedial portal; meta-analysis; meta-regression; outside-in; systematic review; transtibial