ACL Tear Flashcards
What factor contributes to higher ACL tear rate in females?
Neuromuscular
Females have higher valgus moment with landing and relatively weaker hamstrings compared to quads
A genotype within the COL5A1 gene is associated with a reduced risk of which of the following injuries in women?
ACL tear
What is the function of the ACL?
Primary: resist anterior translation of the tibia
Secondary: varus/valgus and rotational restraint
What are the two bundles of the ACL?
Anteromedial: tight in flexion, longer than PM bundle
Posterolateral: tight in extension; rotational stability
Following ACL reconstruction, which of the following tests most closely correlates with patient satisfaction with their reconstructed knee?
Pivot shift test
From flexion to extension; as knee is brought into 20-30 flexion the tibia reduces posteiorly
In an ACL rupture what is the pathognominc bone bruising seen on MRI?
Posterolateral tibia and middle 1/3 of the LFC
What are indications for ACL reconstruction?
1) young, active
2) children
3) prior ACL failure
4) Older highly active pts; >40yo is not contraindication
What is the treatment algorithm for a patient with an ACL and MCL tear?
Allow the MCL to heal, then perform the ACL reconstruction; varus/valgus instability can jeopardize the graft
What is the treatment algorithm for a patient with an ACL and meniscal tear?
Repair the meniscus at time of ACL reconstruction
Better outcomes with meniscal repair when done in conjunction with ACL reconstruction
What is the treatment algorithm for a patient with an ACL and PLC injury?
Reconstruct at the same time as ACL
Where is the correct femoral tunnel placement of an ACL graft?
1) with 1-2mm of posterior rim bone
2) 9-10 o’clock (right knee) or 2-3 o’clock (left knee) in the LFC
Where is the correct tibial tunnel placement of an ACL graft?
10-11mm in front of anterior border of PCL insertion
Start tibial tunnel halfway btw tibial tubercle and postromedial edge of tibia
What are complications of BTB ACL reconstruction?
1) patellar tendon rupture
2) anterior knee pain (10-30%)
3) patellar fx *8-12wks post op)
In biomechanical testing, which ACL graft has the highest maximum load to failure?
Quadruple semitendinosus and gracilis
What is the best predictor of remaining skeletal growth in females?
Onset of menarche; usually 1.5-2yrs of growth remaining
What are factors increase physeal injury in children with ACL tears?
1) oblique tunnel position
2) interference screw fixation
3) high-speed tunnel reaming
4) increasing tunnel diameter (>8mm)
Transphyseal technique rarely leads to growth disturbance
What exercises should be avoided during ACL rehab in the early post-operative period?
1) Open chain quad exercises
2) isokinetic quads from (15-30 degrees)
What exercises are encouraged in the early post-operative period in ACL reconstruction?
1) isometric hamstrings at any angle (least stress)
2) isometric quads or simultaneous quad and hamstrings
3) active knee ROM from 35-90 degrees
In which patient population has ACL bracing been shown to be beneficial?
Skiers
also fall training in skiers has shown to reduce ACL tear incidence
What is the most common cause of ACL failure?
Improper graft tunnel placement (70%)
What is the physical exam findings in a patient with a vertical femoral tunnel on ACL?
Positive pivot shift test and instability with cutting activities due to failure to reconstruct the posterolateral bundle of the AC
What happens to the knee when femoral tunnel is malpositioned during ACL reconstruction?
Too anterior: tight in flexion, loose in extension
Too posterior: tight in extension, loose in flexion
What happens to the knee when tibial tunnel is malpositioned during ACL reconstruction?
Too anterior: tight in flexion, impinges during extension
Too posterior: ACL will impinge on PCL
In a patient with traumatic knee injury and ACL reconstruction, what can lead to continued instability and graft failure?
Unrecognized PLC injury
What two things can help prevent arthrofibrosis in ACL reconstruction?
1) “pre-hab”; initial rehab to regain FROM
2) Delay surgery past initial inflammatory phase
Increased ACL injury rates in women athletes compared to male athletes may be due to muscular imbalance and relative weakness of what muscle group?
Hamstrings
At what range of motion do seated leg extension exercises place the greatest amount of stress on the anterior cruciate ligament?
0-30 degrees
Most surgeons prefer to avoid or limit which of the following exercises in the initial post-operative rehabilitation following ACL reconstruction?
Seated leg extensions
