ACL Anatomy

Arthroscopic Image of Normal Anterior cruciate ligament.

1. Lateral Femoral Condyle
2. Anterior Cruciate Ligament
3. Posterior Cruciate Ligament

ACL Blood Supply

• Middle genicular artery which arises from popliteal A.  The inferior medial and lateral genicular A also vascularize the ACL via the fat pad. (Arnoczky SP, Orthop Clin North Am 1985;16:15)

Posterior view of the knee demonstrating blood supply.

1. Popliteal artery
2. Superior lateral genicular artery
3. Superior medial genicular artery
4. Middle geniculate artery
5. Inferior lateral genicular artery
6. Inferior medial genicular artery

ACL Innervation

• Posterior articular nerve (a branch of the tibial nerve) (Kennedy JC, JBJS 1974;56A:223). Normal ACL has proprioceptive senses that help protect the knee joint during use which are lost after reconstruction

Proton Density MRI of Normal ACL

1. Quadriceps tendon
2. Patella
3. Patellar ligmanet
4. Distal femur (notch area)
5. ACL
6. Tibial Plateau
7. PCL

Sagittal FSE PD image

Inversion Recovery MRI of Normal ACL

1. Quadriceps tendon
2. Patella
3. Patellar ligmanet
4. Distal femur (notch area)
5. ACL
6. Tibial Plateau
7. PCL

Sagittal FSE IR image

A/P Image of a right knee demonstrating a Segond Fracture.

1. Segond fracture (avulsion fracture of lateral tibial plateau) is pathognomonic of ACL injury.  Located posterior to Gerdy's tubercle and superior and anterior to the fibular head (avulsion of lateral capsule).

ACL Hamsting Reconstruction

1. Medial Femoral Condyle
2. PCL
3. Hamsting ACL Reconstruction
4. Lateral Femoral Condyle

• Peak anteromedial bundle ACL relative strain is greater in female than male knees.
• ACL cross-sectional area is smaller  and lateral tibial slope is greater in female knees.  
• Lipps DB, Oh YK, Ashton-Miller JA, Wojtys EM. Morphologic characteristics help explain the gender difference in peak anterior cruciate ligament strain during a simulated pivot landing. Am J Sports Med. 2012 Jan;40(1):32-40.