title: Vertical femoral tunnel placement results in rotational knee laxity after anterior cruciate ligament reconstruction.
abstract: OBJECTIVE
  This retrospective study was performed to relate tunnel position as measured by plain radiographs and magnetic resonance imaging (MRI) to residual pivot shift and to determine its clinical relevance after anterior cruciate ligament reconstruction via central quadriceps tendon autograft.
  
  
  METHODS
  We reviewed 137 arthroscopic anterior cruciate ligament reconstructions via quadriceps tendon autograft with a minimum of 2 years' follow-up. Clinical results were evaluated by use of the Lachman test, pivot-shift test, Lysholm score, and Cybex dynamometer (Lumex, Ronkonkoma, NY). Anterior tibial translation was measured with the KT-1000 arthrometer (MEDmetric, San Diego, CA). Patients were classified into 3 groups based on postoperative pivot-shift and Lachman test findings: group I, both negative; group II, negative Lachman test and positive pivot shift; and group III, both positive. The radiographic analysis was performed via the angle between the tibial and femoral tunnels on plain anteroposterior radiographs, the angle between the tibial tunnel and anterior tibial cortex on the lateral view, and the femoral and tibial tunnel location by use of the ratio method. Postoperative knee MRI was performed, and the angle between the intercondylar anteroposterior axis and femoral tunnel on the axial view and the angle between the joint line and the graft on the oblique coronal and sagittal views were measured.
  
  
  RESULTS
  There were 100 patients in group I, 13 in group II, and 24 in group III. Patients in group I showed the greatest improvement in Lysholm score among the groups, and patients in group III had the greatest side-to-side difference by KT-1000 arthrometer. Tunnel obliquity as measured by the angle between the anteroposterior axis of the femur and the femoral tunnel in the axial view on MRI was greater (P < .05) and the angle between the joint line and the graft on the oblique coronal view was less in group I.
  
  
  CONCLUSIONS
  This study showed a significantly lower Lysholm score and more vertical orientation of the femoral tunnel in the group with residual pivot shift than in the group without pivot shift. Vertical orientation of the femoral tunnel in the axial plane is closely related to residual pivot shift without definite anteroposterior laxity. More oblique positioning of the graft may have advantages in rotational stability, which in turn increase subjective patient satisfaction.
  
  
  METHODS
  Level III, diagnostic study of nonconsecutive patients without consistently applied reference gold standard.
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University College of Medicine, Seoul, South Korea. leemc@snu.ac.kr
authors.forename: Myung Chul
authors.initials: MC
authors.lastname: Lee
authors.forename: Sang Cheol
authors.initials: SC
authors.lastname: Seong
authors.forename: Sahnghoon
authors.initials: S
authors.lastname: Lee
authors.forename: Chong Bum
authors.initials: CB
authors.lastname: Chang
authors.forename: Yoon Keun
authors.initials: YK
authors.lastname: Park
authors.forename: Hyunchul
authors.initials: H
authors.lastname: Jo
authors.forename: Choong Hyun
authors.initials: CH
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000503:physiopathology / Q000601:surgery*; D001182:Arthroscopy / Q000009:adverse effects* / Q000379:methods*; D005260:Female; D005269:Femur / Q000503:physiopathology / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D007718:Knee Injuries / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D052097:Quadriceps Muscle / Q000503:physiopathology; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D012399:Rotation; D012421:Rupture / Q000503:physiopathology / Q000601:surgery; D013710:Tendons / Q000637:transplantation; D013977:Tibia / Q000503:physiopathology