Anterior cruciate ligament injury is typified by a sudden, painful, audible pop noise. The patient is typically unable to return to the ongoing sporting activity, and presents with joint instability, and rapid development of an effusion (hemarthrosis).
Often tender at lateral femoral condyle, lateral tibial plateau, and tibiofemoral joint lines.
A positive Lachman test is most accurate right after the injury and the pivot shift test is more useful in subacute or chronic cases.
History and physical exam usually provide an accurate diagnosis.
X-rays obtained to rule out avulsion fractures or other related conditions, but do not directly identify ACL injury. Magnetic resonance imaging delineates ACL tears, along with associated injury to the menisci and other structures.
Initial treatment for most patients consists of protection, rest, ice, compression, elevation, and analgesia (as appropriate). Subsequent treatment varies by an individual patient's health and fitness status and goals. Treatment may range from minimal or no additional intervention to bracing, physical therapy, and activity modification, and to surgical reconstruction (either early or delayed).
A torn anterior cruciate ligament (ACL) usually occurs as a result of an acute noncontact deceleration injury, forceful hyperextension, or excessive rotational forces about the knee. The ligament may be completely torn, partially torn, or avulsed from its origin or insertion. The ACL is the primary restraint to excessive anterior translation and rotation of the tibia on the femur; therefore, complete ACL disruption typically results in dynamic knee instability or the inability to respond to quick changes in position.
History and exam
Key diagnostic factors
- audible pop
- rapid knee swelling
- inability to return to the ongoing sporting activity
- sensation of knee instability or buckling
- positive Lachman test
- positive pivot shift maneuver
Other diagnostic factors
- tenderness at lateral femoral condyle, lateral tibial plateau
- positive anterior drawer test
- acute trauma
- female sex (after puberty)
- poor technique for landings
- history of previous ACL injury
- aggressive athlete with higher skill level
- use of cleats or spikes
- rough or uneven playing surface
- ground condition/weather
- adolescent, young adults, and middle-aged athletes
1st investigations to order
Investigations to consider
moderate intensity demands
intense dynamic demands
- Medial collateral ligament (MCL) sprain
- Posterior collateral ligament (PCL) sprain
- Lateral collateral ligament (LCL) sprain
- National Athletic Trainers' Association position statement: prevention of anterior cruciate ligament injury
- Consensus statement on prevention, diagnosis and management of paediatric anterior cruciate ligament (ACL) injuries
Anterior cruciate ligament injuryMore Patient leaflets
- Log in or subscribe to access all of BMJ Best Practice
Use of this content is subject to our disclaimer