title: Changes in cross-sectional area of hamstring anterior cruciate ligament grafts as a function of time following transplantation.
abstract: OBJECTIVE
  To measure the cross-sectional area (CSA) of hamstring anterior cruciate ligament (ACL) grafts in humans up to 2 years postoperatively and to estimate the appropriate graft-notch distance (the distance between ACL graft and roof or wall of the notch) at surgery.
  
  
  METHODS
  Case series.
  
  
  METHODS
  Fifty-nine patients, who had consented to have a magnetic resonance imaging (MRI) evaluation postoperatively, underwent endoscopic ACL reconstruction using 3- to 5-strand autogenous hamstring tendons. Intraoperatively, the CSA of the graft was measured using a custom-made area micrometer. Postoperatively, 115 axial MRIs of the grafts (48 at 3 months, 44 at 12 months, and 23 at 24 months) were obtained. They were transmitted to a personal computer and the CSAs of the grafts' midsubstance were calculated. To evaluate the accuracy of the MRI measurement, another 15 patients who consented to have MRI 2 days after surgery were selected and intraoperative graft CSA measurements and graft axial MRI were performed 2 days after surgery.
  
  
  RESULTS
  The CSAs of the grafts measured by MRI 2 days after surgery were well correlated with those directly measured intraoperatively (gamma = 0.905). The CSA of the grafts measured intraoperatively was 43 +/- 5 mm2, and those estimated by MRI at 3, 12, and 24 months were 50 +/- 9 mm2, 54 +/- 9 mm2, and 48 +/- 12 mm2, respectively. The increase in graft diameter at 3, 12, and 24 months was 9% +/- 8%, 13% +/- 10%, and 7% +/- 12%, respectively.
  
  
  CONCLUSIONS
  In humans, the increase in CSA of the ACL graft was smaller compared with previous animal studies. The graft CSA increased up to 29% (13% in diameter) 12 months after surgery. When a 95% confidence interval was used, the percent increase in diameter of the reconstructed graft was estimated to be less than 32% in 95% of the cases. When the graft diameter was 7, 8, or 9 mm, a 1.1-, 1.3-, or 1.4-mm graft-notch distance, respectively, was suitable for impingement-free graft during postoperative periods with 95% of probability.
  
  
  METHODS
  Level IIII.
authors.affiliation: Department of Orthopaedic Surgery, Hoshigaoka Koseinenkin Hospital, Osaka, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hamada
authors.forename: Konsei
authors.initials: K
authors.lastname: Shino
authors.forename: Shuji
authors.initials: S
authors.lastname: Horibe
authors.forename: Tomoki
authors.initials: T
authors.lastname: Mitsuoka
authors.forename: Yukiyoshi
authors.initials: Y
authors.lastname: Toritsuka
authors.forename: Norimasa
authors.initials: N
authors.lastname: Nakamura
mesh_terms: D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000637:transplantation* / Q000648:ultrastructure; D000886:Anthropometry; D001182:Arthroscopy / Q000379:methods; D001863:Bone Screws; D001864:Bone Wires; D005260:Female; D005269:Femur / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D007432:Intraoperative Period; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D013314:Stress, Mechanical; D013710:Tendons / Q000637:transplantation* / Q000648:ultrastructure; D013977:Tibia / Q000601:surgery; D013997:Time Factors; D014182:Transplantation, Autologous; D019737:Transplants / Q000706:statistics & numerical data*