title: Case series: Revision anterior cruciate ligament reconstructions using patellar tendon autografts.
abstract: BACKGROUND
  Using intra-operative findings and clinical results, including return to play (RTP) at the pre-injury level, this study investigated the causes of primary graft failure after revision anterior cruciate ligament (ACL) reconstruction with bone-patellar-tendon-bone (BPTB) autografts.
  
  
  METHODS
  A total of 54 patients were followed for a mean of 38.2 ± 10.2 months post-surgery. Subjective and objective results were evaluated using single assessment numeric evaluation (SANE) scores, Lachman tests, KT-2000 arthrometer results, and pivot-shift tests. The change in each patient's Tegner activity scale and RTP at the pre-injury level were also evaluated.
  
  
  RESULTS
  Inappropriate positioning of the tunnels was the most important reason (54%) for primary graft failure. After revision surgery, anterior knee stability was significantly improved (1.2 (mean) ± 1.2 (SD)mm vs 4.5(mean) ± 1.9 (SD)mm; P < 0.01). Two (4%) patients sustained revision graft ruptures while two (4%) sustained contralateral knee ACL tears. The rate of RTP at the pre-injury level was 67% (36 patients), and mean SANE scores at the time of RTP were higher than before surgery (74.8 ± 13.8 points vs 24.1 ± 16.4; P<0.001). The average time from primary graft failure to revision surgery was shorter (12.2 (mean) ± 4.0 (SD) vs 37.6 (mean) ± 8.8 (SD)months; P < 0.01) and the ratio of major cartilage injury was lower (39% vs 83%; P < 0.05) in the RTP group than that in the non-RTP group.
  
  
  CONCLUSIONS
  The time from primary graft failure to revision surgery and the extent of the cartilage injury are major factors in RTP after revision ACL reconstructions.
authors.affiliation: Department of Orthopaedics, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyou-ku, Tokyo 113-8421, Japan. Electronic address: ytakaza@juntendo.ac.jp.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Takazawa
authors.affiliation: Department of Orthopaedics, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyou-ku, Tokyo 113-8421, Japan. Electronic address: hrikeda@juntendo.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ikeda
authors.affiliation: Department of Orthopaedics, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyou-ku, Tokyo 113-8421, Japan. Electronic address: saita0617@hotmail.com.
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Saita
authors.affiliation: Department of Orthopaedics, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyou-ku, Tokyo 113-8421, Japan. Electronic address: ishijima@juntendo.ac.jp.
authors.forename: Muneaki
authors.initials: M
authors.lastname: Ishijima
authors.affiliation: Department of Orthopaedics, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyou-ku, Tokyo 113-8421, Japan. Electronic address: masataka_nagayama@yahoo.co.jp.
authors.forename: Masataka
authors.initials: M
authors.lastname: Nagayama
authors.affiliation: Department of Orthopaedics, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyou-ku, Tokyo 113-8421, Japan. Electronic address: harukago@juntendo.ac.jp.
authors.forename: Haruka
authors.initials: H
authors.lastname: Kaneko
authors.affiliation: Department of Orthopaedics, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyou-ku, Tokyo 113-8421, Japan. Electronic address: yo_pei0423@hotmail.com.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Kobayashi
authors.affiliation: Department of Orthopaedics, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyou-ku, Tokyo 113-8421, Japan. Electronic address: shada@juntendo.ac.jp.
authors.forename: Shinnosuke
authors.initials: S
authors.lastname: Hada
authors.affiliation: Department of Orthopaedics, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyou-ku, Tokyo 113-8421, Japan. Electronic address: rsadatsu@juntendo.ac.jp.
authors.forename: Ryo
authors.initials: R
authors.lastname: Sadatsuki
authors.affiliation: Department of Orthopaedics, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyou-ku, Tokyo 113-8421, Japan. Electronic address: k-kaneko@juntendo.ac.jp.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kaneko
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D064592:Autografts; D050376:Bone-Patellar Tendon-Bone Grafting / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007718:Knee Injuries / Q000601:surgery*; D065466:Lysholm Knee Score; D008297:Male; D017847:Patellar Ligament / Q000637:transplantation*; D012086:Reoperation; D012189:Retrospective Studies; D012421:Rupture; D013997:Time Factors; D014182:Transplantation, Autologous; D016896:Treatment Outcome
keywords: Anterior cruciate ligament reconstruction; Clinical study; Graft failure; Patellar tendon autograft; Tunnel placement