title: Tibial tunnel enlargement following anterior cruciate ligament reconstruction with patellar tendon autograft.
abstract: OBJECTIVE
  The purpose of this study was to prospectively evaluate changes in the tibial bone tunnel following endoscopic anterior cruciate ligament (ACL) reconstruction with patellar tendon autograft. We used computed tomography (CT) sequentially to monitor the time course of these changes over a 2-year period and correlated the results to clinical outcome and instrumented laxity measurements.
  
  
  METHODS
  Case series.
  
  
  METHODS
  Thirty-four patients (11 women, 23 men; mean age, 26.4 +/- 4.5 years) who underwent endoscopic patellar tendon ACL reconstruction, were evaluated clinically according to IKDC, Lysholm, and Tegner scores as well as with respect to changes in tibial tunnel morphology over a 2-year period. Subsequent CT scans were performed at 1 and 6 weeks and at 3, 6, 12, and 24 months postoperatively. The tibial bone tunnel was measured in the sagittal and coronal planes at 5 different levels (L1 to L5).
  
  
  RESULTS
  The diameters of the tibial tunnel increased an average overall by 30.6% in the sagittal plane and 16.4% in the coronal plane within 2 years. The enlargement was significantly higher (P <.05) in the mid portion of the tunnel (L 2/3: 44.0% and 47.9% in the sagittal and 29.8% and 29.9% in the coronal plane, respectively), which resulted in a uniform cavity-type appearance. The percentage of change in tunnel size was significantly higher (P <.05) within the first 6 weeks following surgery compared with all other time intervals. No correlation between the amount of tunnel enlargement and the clinical results or between tunnel enlargement and KT-1000 measurements could be detected.
  
  
  CONCLUSIONS
  Endoscopic ACL reconstruction is associated with tibial tunnel enlargement, which is already present within weeks following surgery. However, no negative effects on the clinical results were found over a 24-month period in our study population.
authors.affiliation: University Hospital for Traumatology, Innsbruck, Austria. christian.fink@uibk.ac.at
authors.forename: C
authors.initials: C
authors.lastname: Fink
authors.forename: M
authors.initials: M
authors.lastname: Zapp
authors.forename: K P
authors.initials: KP
authors.lastname: Benedetto
authors.forename: W
authors.initials: W
authors.lastname: Hackl
authors.forename: C
authors.initials: C
authors.lastname: Hoser
authors.forename: M
authors.initials: M
authors.lastname: Rieger
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D016001:Confidence Intervals; D004724:Endoscopy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D015588:Observer Variation; D011446:Prospective Studies; D013710:Tendons / Q000637:transplantation*; D013977:Tibia / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed; D014182:Transplantation, Autologous