title: MR imaging of stable posterior cruciate ligament grafts in 21 arthroscopically proven cases.
abstract: OBJECTIVE
  To describe the magnetic resonance (MR) appearance of intact posterior cruciate ligament (PCL) grafts.
  
  
  METHODS
  Thirty-one postoperative MR examinations were performed in 21 grafts of 20 patients after PCL reconstruction. All 21 grafts were proven to be intact on second-look arthroscopic examination. Two musculoskeletal radiologists retrospectively analyzed the MR findings and reached decisions by consensus. The signal intensity (SI) of the graft on proton density-weighted and T2-weighted images, as well as the shapes, locations, and segments of increased SI were recorded. The graft thickness was also recorded and correlated to elapsed time since reconstructive surgery.
  
  
  RESULTS
  The SI of the graft was high (15/31, 48%), intermediate (10/31, 32%), or low (6/31, 19%) on proton density-weighted images, and high (9/31, 29%), intermediate (6/31, 19%), or low (16/31, 52%) on T2-weighted images. The graft SI decreased significantly as postoperative time elapsed. The shape of the increased SI within the grafts was band-like (14/25, 56%) or focal (11/25, 44%). The increased SI was located in the proximal (18/25, 72%), middle (21/25, 82%), and distal (12/25, 48%) segments. In the axial plane, the location of increased SI was intrasubstance (19/25, 76%) or peripheral (10/25, 40%). A 'focal' shape of increased SI was found significantly more in Achilles tendon allografts, while a band-like shape was more frequent in autogenous double-loop hamstring tendon grafts. Graft thickness ranged from 5-15 mm. The difference in graft thickness relative to postoperative time was not statistically significant (p = 0.79).
  
  
  CONCLUSIONS
  Stable PCL grafts commonly showed an increased SI at any segment or location, even though they were stable. The shape of increased SI differed according to allograft donor sites. However, SI tended to decrease as time elapsed.
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Young Cheol
authors.initials: YC
authors.lastname: Yoon
authors.forename: Hye Won
authors.initials: HW
authors.lastname: Chung
authors.forename: Jin Hwan
authors.initials: JH
authors.lastname: Ahn
mesh_terms: D000293:Adolescent; D000328:Adult; D001182:Arthroscopy / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D016119:Posterior Cruciate Ligament / Q000473:pathology* / Q000637:transplantation*; D011183:Postoperative Complications / Q000175:diagnosis; D012189:Retrospective Studies; D013997:Time Factors; D019737:Transplants / Q000706:statistics & numerical data*