Anterior Cruciate Ligament Tear Flashcards
What is the anatomical loation of the anterior cruciate ligament (ACL)?
It originates on the lateral condyle of the femur and inserts onto the anterior intercondylar area of the tibia
What is the function of the anterior cruciate ligament?
It functions to stabilise the knee joint by preventing anterior tibial subluxation
What is the most commonly injured ligament of the knee?
Anterior cruciate ligament
What is the mechanism of injury associated with anterior cruciate ligament tears?
It involves non-contact sport injuries in which the patient lands on a leg and then quickly pivots in the opposite direction – resulting in a valgus twisting injury
What five clinical features of anterior cruciate ligament tears?
Knee Pain
Knee Swelling
Sudden Popping Sound
Knee Instability
Reduced Knee Movement
What four investigations are used to diagnose an anterior cruciate ligament tear?
Anterior Draw Test
Lachman’s Test
Knee X-Rays
MRI Scans
How is the anterior draw test conducted?
It involves the patient lying supine with their knees flexed at 90 degrees
The examiner then wraps the hand around the proximal tibia with their fingers around the back of the knee
It is important to note that the examiners thumb should be positioned over the tibial tuberosity
The tibia is then pulled anteriorly, and the examiner notes any anterior movement of the tibia on the femur
What is a positive anterior draw test?
There is significant anterior movement of the tibia on the femur
What is the gold standard clinical examination test used to diagnose anterior cruciate ligament tears?
Lachman’s Test
How is the Lachman’s test conducted?
It involves the patient lying supine with their knees flexed at 30 degrees
The examiner then holds the lower leg with their dominant hand, with their thumb on the tibial tuberosity and fingers over the calf
The non-dominant hand should hold the thigh just above the patella
The examiner uses their dominant hand to pull the tibia forwards on the femur, whilst the other hand stabilises the femur
The examiner notes any anterior movement of the tibia on the femur
What is a positive Lachman’s test?
There is significant anterior movement of the tibia on the femur
What are the five features of anterior cruciate ligament tears on knee x-rays?
Anterior Tibial Subluxation
Knee Joint Effusion
Deep Lateral Sulcus Sign
Segond Fracture
Arcuate Fracture
What is the deep lateral sulcus sign?
It is a depression on the lateral femoral condyle, representing an impaction fracture
What is a segond fracture?
It is an avulsion fracture of the knee, which involves the lateral aspect of the tibia plateau
What is an arcuate fracture?
It is an avulsion fracture of the proximal fibula - at the site of insertion of the arcuate ligament complex
