Serial magnetic resonance imaging of hamstring anterior cruciate ligament autografts during the first year of implantation

Abstract

A prospective, observational study was performed to document the serial changes in the magnetic resonance signal of devascularized, hamstring ACL autografts during the 1st year of implantation. Twenty-one ACL deficient knees (14 chronic, 7 acute) were reconstructed. Instability developed in five knees within the first 6 months of graft implantation (24%). Magnetic resonance examinations were performed at 1, 6, 12, 24, 36, and greater than 48 weeks postoperatively (repetition time 1500, echo delay time = 50). A total of 104 scans were reviewed (average, five per knee). The ACL graft was divided into four unequal size zones for analysis. The proximal, middle, and distal thirds of the intraarticular portion of the graft and the portion of the graft within the tibial tunnel were independently analyzed. The magnetic resonance signal in each portion of the graft was graded on a scale with (I) being a normal signal, (II) greater than 50% of the total volume of the graft having a normal signal, (III) less than 50% of the graft having a normal signal, and (IV) 100% of the graft having an increased signal. The increased magnetic resonance signal of the ACL graft was observed to be regionalized and confined to the distal two-thirds of the intraarticular portion of the graft. The portion of the graft exiting the femoral tunnel and within the tibial tunnel retained a normal magnetic resonance signal. The increases in magnetic resonance graft signal were time-dependent, became well established by 3 months, and remained unchanged at 1 year. The clinical outcome could not be predicted based on the magnetic resonance signal of the graft.

Magnetic Resonance Imaging Evaluation of Patellar Tendon Graft Remodelling after Anterior Cruciate Ligament Reconstruction with or without Platelet-Rich Plasma

“…27 There are 4 remodelling stages based on the signal intensity of the graft. 13 Grade I indicates that the graft is homogeneously hypointense, indistinguishable from the posterior cruciate ligament and patellar ligament. Grade II indicates >50% normal ligament with patches yielding increased signals.…”

Principles for placing the tibial tunnel and avoiding roof impingement during reconstruction of a torn anterior cruciate ligament

“…Pathognomonic findings include an increase in signal confined to the distal twothirds of the intra-articular pathway of the graft and posterior bowing of the graft caused by contact with the intercondylar roof [10, 17,18,20].…”

Anterior cruciate ligament reconstruction: the diagnostic value of MRI

“…Some authors have reported good visibility of the neoligament on MRI and have recommended it for follow-up examination [2,5,6,17,21]. Others have observed significant changes in the signal intensity of the reconstructed ligament following operation and have concluded that the neoligament cannot be evalu-ated with MRI [12,18,20,22]. Most of the studies were retrospective and merged the results of several MRI examinations undertaken at different intervals following surgery.…”