Graft anatomy:
Autologous bone–patella tendon–bone graft
Autologous four-strand hamstring graft = doubled semitendinosus and gracilis tendon graft
Replace the anteromedial bundle (AMB) only
Femoral tunnel:
Sagittal plane: line along posterior cortex of the femur and line along the roof of the intercondylar notch. Inferior portion of the tunnel to be located at intersection of these two lines
Coronal plane: intraarticular portion of the femoral tunnel should open at the superolateral posterior margin of the intercondylar notch, i.e., between 10 and 11 o'clock in right knee and between 1 and 2 o'clock in left
Tibial tunnel:
Sagittal plane:
Tibial tunnel should be parallel and posterior to Blumansaat's line (line drawn along the intercondylar roof)
Distal portion of the tunnel near tibial tuberosity
Intraarticular opening completely posterior to intersection of Blumensaat line and tibia
Lucency is common around the graft and sclerosis at the tunnel margins on follow-up are normal finginds
Coronal plane:
Tibial tunnel should open at intercondylar eminence
Normal ACL graft:
Low signal; intermediate signal bet 4 to 8 months, resolve by 12 months
Graft failure: Early failure: within 6 months, most due to poor technique
Late failure: after 1 year, most due to repeat trauma leading to graft tear
Complications:
Roof impingement
Partial tear
Complete tear
Arthrofibrosis (cylops)
Tunnel cyst
Iliotibial band syndrome
Hardware complications: displacement, fracture
Infection
Roof impingement:
Usually secondary to abnormal tibial tunnel
Graft is shown in contact with anteoinferior margin of intercondylar roof
Graft may show posterior bowing
Partial tear:
Focal increased signal in graft
Differential would include 'normal ligamentization'
Complete tear:
Most are due to trauma
Direct visulization of tear
Indirect signs: large effusion, pivot shift bone contusions, fluid filled graft defect, horizaontal orientation of graft, laxity of graft
Arthrofibrosis:
Scar in at least one compartment
Cylops (focal): anterior arthrofibrosis is nodular
Increased incidence in ACL reconstruction within 4 weeks of trauma
Diffuse:
Tunnel cyst:
Small fluid signal within tunnel in 1st year is common, and is disppears by 18 months
Tibia far more common than femur
Reference:
Bencardino JT et al. MR imaging of complications of anterior cruciate ligament reconstruction. Radiographics 2009;29;2115-2126
Autologous bone–patella tendon–bone graft
Autologous four-strand hamstring graft = doubled semitendinosus and gracilis tendon graft
Replace the anteromedial bundle (AMB) only
Femoral tunnel:
Sagittal plane: line along posterior cortex of the femur and line along the roof of the intercondylar notch. Inferior portion of the tunnel to be located at intersection of these two lines
Coronal plane: intraarticular portion of the femoral tunnel should open at the superolateral posterior margin of the intercondylar notch, i.e., between 10 and 11 o'clock in right knee and between 1 and 2 o'clock in left
Tibial tunnel:
Sagittal plane:
Tibial tunnel should be parallel and posterior to Blumansaat's line (line drawn along the intercondylar roof)
Distal portion of the tunnel near tibial tuberosity
Intraarticular opening completely posterior to intersection of Blumensaat line and tibia
Lucency is common around the graft and sclerosis at the tunnel margins on follow-up are normal finginds
Coronal plane:
Tibial tunnel should open at intercondylar eminence
Normal ACL graft:
Low signal; intermediate signal bet 4 to 8 months, resolve by 12 months
Graft failure: Early failure: within 6 months, most due to poor technique
Late failure: after 1 year, most due to repeat trauma leading to graft tear
Complications:
Roof impingement
Partial tear
Complete tear
Arthrofibrosis (cylops)
Tunnel cyst
Iliotibial band syndrome
Hardware complications: displacement, fracture
Infection
Roof impingement:
Usually secondary to abnormal tibial tunnel
Graft is shown in contact with anteoinferior margin of intercondylar roof
Graft may show posterior bowing
Partial tear:
Focal increased signal in graft
Differential would include 'normal ligamentization'
Complete tear:
Most are due to trauma
Direct visulization of tear
Indirect signs: large effusion, pivot shift bone contusions, fluid filled graft defect, horizaontal orientation of graft, laxity of graft
Arthrofibrosis:
Scar in at least one compartment
Cylops (focal): anterior arthrofibrosis is nodular
Increased incidence in ACL reconstruction within 4 weeks of trauma
Diffuse:
Tunnel cyst:
Small fluid signal within tunnel in 1st year is common, and is disppears by 18 months
Tibia far more common than femur
Reference:
Bencardino JT et al. MR imaging of complications of anterior cruciate ligament reconstruction. Radiographics 2009;29;2115-2126
