ANTERIOR CRUCIATE LIGAMENT INJURY

History

. Mechanism: sudden deceleration, cutting, valgus force contact or
noncontact, hyperextension
. Patient may recall pop or tearing sensation – 80%
. Painful, inability to continue activity
. Rapid hemarthrosis within 3 hours – 80%
. If chronicmay have history of recurrent instability
. Common sports: skiing, basketball, volleyball, football, soccer
. May be isolated or in conjunction with multiple ligament injuries –
medial collateral (MCL), posterior cruciate (PCL), posterolateral or
knee dislocation
. Often associated with meniscal pathology and/or articular cartilage
injury
. Knee instability complaints: jumping, twisting, deceleration, cutting
activities
Physical exam
.Acute: effusion, bloody hemarthrosis if aspirated
. Joint line tenderness suggestive of associated meniscal pathology
. Ligament laxity exam – compare to uninjured knee
. Abnormal Lachman testmost sensitive test
. Increased anterior tibial translation @ 20–30. knee fusion
. Positive pivot shift test (Losee, Hughston, flexion rotator drawer
variants)
. Pathognomonic of complete anterior cruciate ligament (ACL) injury
. Subluxation – Reduction phenomenon related to axial compression,
valgus loading, and flexion/extension occurred at 15–30.
. Associated ligament laxity tests
. MCL – Valgus laxity at 0., 30.
. Lateral collateral ligament – Valgus laxity at 0., 30.
. PCL – Increased posterior translation at 90. (posterior drawer),
posterior sag test (gravity flexion test)
. Posterolateral – Increased posterolateral rotation, increased
external tibial rotation, asymmetric dial test
. Locked knee –Displaced bucket handle meniscal tear, rule out associated
ACL injury
Studies
. Radiographs
. AP, lateral, tunnel,Merchant (four views)
. Generally normal
. Lateral capsular sign (Segond fracture): marginal avulsion fracture
fromanterolateral tibial plateau pathognomonic
. Lateral notch sign (chronic ACL): accentuation of indentation
of sulcus terminalis in lateral femoral condyle; rarely seen with
PCL/posterolateral corner (PLC) injury
. Chronic ACL deficiency: periarticular osteophytes, tibial eminence
peaking, intercondylar notch narrowing
. MRI
. Highly sensitive/specific for ACL injury
. Generally does not differentiate between partial or complete
ACL injury
. Associated meniscal pathology common
. Bone bruise noted (80%), lateral femoral condyle, lateral tibial
condyle most common
. Effusion frequently noted
. MRI value: detecting associated meniscal pathology and articular
cartilage pathology
. KT-1000
. Instrumented laxity testing device
. Measures side-to-side differences (SSD) and absolute translation
. Dx: maximum manual SSD >3 mm; 30-pound anterior translation
>10mm
Differential diagnosis
. Hemarthrosis
. ACL, patellar dislocation, peripheral meniscal tear, intra-articular
fracture, PCL injury, popliteus tendon avulsion
. Instability
. Patellar instability
. Meniscal tear (e.g., bucket handle)
. Posterolateral
. Quad weakness – giving way with level walking/standing