title: Increased risk of revision after anteromedial compared with transtibial drilling of the femoral tunnel during primary anterior cruciate ligament reconstruction: results from the Danish Knee Ligament Reconstruction Register.
abstract: OBJECTIVE
  The goal was to study revision rates and clinical outcome after anterior cruciate ligament (ACL) reconstruction using the anteromedial (AM) technique versus the transtibial (TT) technique for femoral drill hole placement.
  
  
  METHODS
  A total of 9,239 primary ACL reconstruction procedures were registered in the Danish Knee Ligament Reconstruction Register between January 2007 and December 2010. The failure of the 2 different femoral drilling techniques was determined using revision ACL reconstruction as the primary endpoint. As secondary endpoints, we used the pivot-shift test and instrumented objective test as well as patient-reported outcome, registered in the Danish Knee Ligament Reconstruction Register. Relative risks (RRs) with 95% confidence intervals (CI) were calculated.
  
  
  RESULTS
  We identified 1,945 AM and 6,430 TT primary ACL procedures. The cumulative revision rates for ACL reconstruction after 4 years with the AM and TT techniques were 5.16% (95% CI: 3.61%, 7.34%) and 3.20% (95% CI: 2.51%, 4.08%), respectively. The adjusted overall RR for revision ACL surgery in the AM group was 2.04 (95% CI: 1.39, 2.99), compared with the TT group. Use of the AM technique increased from 13% of all operations in 2007 to 40% in 2010. AM technique was further associated with increased RRs of positive pivot shift of 2.86 (95% CI: 2.40, 3.41) and sagittal instability of 3.70 (95% CI: 3.09, 4.43), compared with the TT technique.
  
  
  CONCLUSIONS
  This study found an increased risk of revision ACL surgery when using the AM technique for femoral drill hole placement, compared with the TT technique, in the crude data as well as the stratified and adjusted data. Our finding could be explained by technical failures resulting from introduction of a new and more complex procedure or by the hypothesis put forward in prior studies that compared with a nonanatomic graft placement, a greater force is carried by the anatomic ACL reconstruction and, hence, there is a concomitant higher risk of ACL rupture.
  
  
  METHODS
  Level II, prospective comparative study.
authors.affiliation: Division of SportsTrauma, Department of Orthopaedic Surgery, Aarhus University Hospital, Denmark. lrw@dce.au.dk
authors.forename: Lene
authors.initials: L
authors.lastname: Rahr-Wagner
authors.forename: Theis Muncholm
authors.initials: TM
authors.lastname: Thillemann
authors.forename: Alma Becic
authors.initials: AB
authors.lastname: Pedersen
authors.forename: Martin Carøe
authors.initials: MC
authors.lastname: Lind
mesh_terms: D000293:Adolescent; D000328:Adult; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods* / Q000706:statistics & numerical data; D001182:Arthroscopy / Q000379:methods* / Q000706:statistics & numerical data; D001265:Athletic Injuries / Q000601:surgery; D016001:Confidence Intervals; D016208:Databases, Factual; D003718:Denmark; D005260:Female; D005269:Femur / Q000601:surgery*; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis / Q000453:epidemiology; D053208:Kaplan-Meier Estimate; D008297:Male; D008592:Menisci, Tibial / Q000601:surgery; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology; D016016:Proportional Hazards Models; D011446:Prospective Studies; D020127:Recovery of Function; D012042:Registries; D012086:Reoperation / Q000706:statistics & numerical data; D012306:Risk; D012720:Severity of Illness Index; D013977:Tibia / Q000601:surgery*; D000070600:Tibial Meniscus Injuries; D055815:Young Adult