title: Graft bending angle is correlated with femoral intraosseous graft signal intensity in anterior cruciate ligament reconstruction using the outside-in technique.
abstract: BACKGROUND
  The purposes of this study were as follows: 1) to determine the correlation between the bending angle of the anterior cruciate ligament (ACL) graft at the femoral tunnel and the magnetic resonance imaging (MRI) signal intensity of the ACL graft and 2) to analyze the difference in the MRI signal intensity of the reconstructed ACL graft in different areas of the graft after single-bundle hamstring autograft ACL (SB ACL) reconstruction using an outside-in (OI) technique with bone-sparing retro-reaming.
  
  
  METHODS
  Thirty-eight patients who underwent SB ACL reconstruction with the hamstring tendon autograft using the OI technique were enrolled in this study. All patients were assessed using three-dimensional computed tomography (CT) to evaluate femoral tunnel factors, including tunnel placement, tunnel length, tunnel diameter, and femoral tunnel bending angle. At a mean of 6.3±0.8months after surgery, 3.0-T MRI was used to evaluate the graft signal intensity using signal/noise quotient for high-signal-intensity lesions.
  
  
  RESULTS
  Among various femoral tunnel factors, only the femoral tunnel bending angle in the coronal plane was significantly (p=0.003) correlated with the signal/noise quotient of the femoral intraosseous graft. The femoral intraosseous graft had significantly (p=0.009) higher signal intensity than the other graft zone. Five cases (13.2%) showed high-signal-intensity zones around the femoral tunnel but not around the tibial tunnel.
  
  
  CONCLUSIONS
  After ACL reconstruction using the OI technique, the graft bending angle was found to be significantly correlated with the femoral intraosseous graft signal intensity, indicating that increased signal intensity by acute graft bending might be related to the maturation of the graft.
  
  
  METHODS
  This was a retrospective comparative study with Level III evidence.
authors.affiliation: Department of Orthopaedic Surgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, 29 Saemunan-ro, Jongno-gu, Seoul 110-746, Republic of Korea. Electronic address: jha3535@naver.com.
authors.forename: Jin Hwan
authors.initials: JH
authors.lastname: Ahn
authors.affiliation: Department of Orthopaedic Surgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, 29 Saemunan-ro, Jongno-gu, Seoul 110-746, Republic of Korea. Electronic address: kneedoc@naver.com.
authors.forename: Hwa Jae
authors.initials: HJ
authors.lastname: Jeong
authors.affiliation: Department of Orthopedic Surgery, Seoul National University College of Medicine, Bundang Hospital, 166 Gumi-ro, Bundang-gu, Seongnam-si, Gyeonggi-do 463-707, Republic of Korea. Electronic address: smcos1@hanmail.net.
authors.forename: Yong Seuk
authors.initials: YS
authors.lastname: Lee
authors.affiliation: Department of Orthopaedic Surgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, 29 Saemunan-ro, Jongno-gu, Seoul 110-746, Republic of Korea. Electronic address: wonnypia@hanmail.net.
authors.forename: Jai Hyung
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Orthopaedic Surgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, 29 Saemunan-ro, Jongno-gu, Seoul 110-746, Republic of Korea. Electronic address: htr107@naver.com.
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Orthopaedic Surgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, 29 Saemunan-ro, Jongno-gu, Seoul 110-746, Republic of Korea. Electronic address: colorko@naver.com.
authors.forename: Taeg Su
authors.initials: TS
authors.lastname: Ko
mesh_terms: D000328:Adult; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D001182:Arthroscopy; D005269:Femur / Q000000981:diagnostic imaging* / Q000601:surgery; D000070632:Hamstring Tendons / Q000000981:diagnostic imaging* / Q000637:transplantation*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D012189:Retrospective Studies; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery; D014057:Tomography, X-Ray Computed; D014182:Transplantation, Autologous; D055815:Young Adult
keywords: Anterior cruciate ligament; Femoral tunnel bending angle; Outside-in technique; Signal/noise quotient