Anterior cruciate ligament graft tear

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Anterior cruciate ligament graft tears can occur as complications of anterior cruciate ligament reconstruction or as a consequence of a traumatic reinjury.

Epidemiology

An anterior cruciate ligament reinjury occurs in about 7% of patients with an anterior cruciate ligament reconstruction .

Risk factors

Factors that increase the likelihood of developing anterior cruciate ligament graft tear or reinjury are :

  • younger age (<25 years)
  • high level of activity
  • high-risk cutting/pivoting sports and activities (e.g. football/soccer)
  • hamstring autograft
  • improper tunnel placement
  • reinjury during the ligamentization period (in particular 4-8 months after reconstruction)

Clinical presentation

Common complaints include recurrent or persistent pain, instability, laxity or limited range of motion after anterior cruciate ligament reconstruction. History might reveal a reinjury.

Complications

Anterior cruciate ligament graft tears can lead to the following conditions :

Pathology

An anterior cruciate ligament graft tear is a partial or complete discontinuity of the graft and accounts as a graft failure.

Etiology

Causes of anterior cruciate ligament graft tears include the following :

  • surgical errors (e.g. tunnel malposition and subsequent graft shearing)
  • poor graft incorporation
  • untreated concomitant injuries (e.g. posterolateral corner injury)
  • repeat traumatic injury
  • septic arthritis
Location

Anterior cruciate ligament graft tears may be located in the intra-articular portion of the graft or within the femoral or tibial tunnels . The posterolateral bundle is more frequently affected than the anteromedial bundle .

Radiographic features

Plain radiograph

Plain radiographs are of limited value in the detection of an anterior cruciate ligament graft tear. They might depict secondary signs such as an anterior tibial translation or potential causes like tunnel malposition or signs of screw divergence.

CT

CT might be done for the evaluation of tibial and femoral tunnels in the setting of preoperative planning.

MRI

MRI allows the detection and evaluation of suspected anterior cruciate ligament graft tears, which can be best depicted in coronal and sagittal views. In addition, MRI can be used for the workup of concomitant chondral, meniscal and ligamentous injuries .

Primary imaging signs:

  • graft fiber discontinuity or fluid-signal intensity defect
  • abnormal (horizontal) fiber orientation
  • lax graft fibers or fiber disarray
  • graft thinning
  • focal area of increased graft signal

Secondary imaging signs:

  • bone bruises in the lateral compartment at the condylopatellar sulcus and the posterolateral tibia
  • anterior tibial translation
  • uncovering of the posterior horn of the lateral meniscus
  • buckling of the posterior cruciate ligament

Radiology report

The radiological report should include a description of the following :

  • location and grade of the graft tear (partial tear, disruption)
  • possible etiology if evident
  • concomitant chondral injuries and meniscal tears
  • possible concomitant ligamentous injuries
  • evidence of malalignment

Treatment and prognosis

The management of anterior cruciate ligament graft injury depends on clinical signs and symptoms on patient age and activity as well as on concomitant injuries.

Partial anterior cruciate ligament graft tears can be managed conservatively .

Full-thickness tears in the setting of recurrent instability and/or malalignment are likely treated with graft revision surgery. Depending on the exact etiology of the graft rupture and associated findings such as chondral and/or meniscal injuries revision surgery might be done as a one-stage or two-stage procedure .

Differential diagnosis

Conditions which can mimic the presentation and/of the appearance of an anterior cruciate ligament graft tear include :

  • graft stretching
  • mucoid degeneration of the graft
  • graft impingement
  • arthrofibrosis
  • graft ligamentization
    • focal areas of signal alteration
    • occurs in immature grafts (up to 4 years after ACL reconstruction)
  • multistranded hamstring grafts
    • focal areas of signal alteration

See also