acl/pcl

ANteriomedial ACL tight in

flexion

posterolateral acl tight in

extension

What are the two ACL bundles and when are they tight?

Anteriomedial (tight in flexion), posterolateral (tight in extension)

ACL primary restaints

anterior tibial translation (20-30 flexion)

secondary roles of the acl

Restricts tibial rotation and supports valgus/varus with collateral ligament damage

most common MOI for ACL tears

Non-contact—cutting, landing, deceleration

What are subjective signs of ACL injury?

"Pop," hemarthrosis (within 2-6 hours), instability, unable to continue play

objective signs of ACL injury

Restricted extension, lateral joint tenderness, positive Lachman and anterior drawer test

What are the PCL bundles and when are they tight?

Anterolateral (tight in flexion), Posteromedial (tight in extension)

What does the PCL restrain?

Posterior tibial translation (stronger than ACL)

Common MOI for PCL injury?

Dashboard injury (MVA), fall on flexed knee, hyperflexion

Best test for PCL?

Posterior drawer test and sag sign

Meniscus function?

Stability, shock absorption, load distribution, nutrient dispersion

Medial vs Lateral Meniscus key differences?

Medial: C-shaped, less mobile, more often injured

Lateral: O-shaped, more mobile, looser capsule attachment

Meniscal blood zones?

• Red: Outer 1/3 (vascular, better healing)

• Red-white: Middle

• White-white: Inner (avascular, poor healing)

LCL vs MCL injury differences?

• LCL: Less common, varus force, more complex

• MCL: Most common, valgus force, often isolated

Most common direction of dislocation? patellar

lateral

MOI for patellar dislocation?

Tibial ER + femoral IR with quadriceps contraction near extension

Key symptoms/signs? patellar dislocation

Pop/shift, pain, swelling, positive lateral apprehension test

Ottawa knee rules

• Age ≥ 55

• Isolated patellar tenderness

• Tender fibular head

• Can't flex knee to 90°

• Can't weight bear immediately or in ER (4 steps)

Classic symptoms? patellofemoral pain

Pain with stairs, squatting, prolonged sitting, running/jumping

contributing factors PFPS

• Increased Q-angle

• Overpronation

• Weak hip abductors/extensors

• VMO dysfunction

• Tight ITB, hamstrings, rectus femoris

rehab focus PFPS

• Address intrinsic/extrinsic factors

• Strengthen hip/core

• Stretch shortened muscles

• Optional orthotics

What are the main MOIs for ACL injuries?

1. Valgus stress after MCL injury (usually contact)

2. Deceleration/internal rotation (non-contact)

3. Hyperextension (less common, usually not isolated)

4. Quads active mechanism – rapid deceleration or awkward landing with anterior tibial translation caused by strong quadriceps contraction

How does the "quads active mechanism" contribute to ACL injuries?

• Strong quad contraction pulls the tibia forward during deceleration/landing

• Increased risk if foot is planted (friction from shoe-surface interface)

• Results in anterior tibial dislocation → ACL rupture

What are intrinsic contributing factors to PFPS?

• Lower chain misalignment (e.g. valgus knees)

• Excessive foot pronation

• Weak glutes/core (poor pelvic control)

• Tight muscles: ITB, hamstrings, rectus femoris, calves

• Vastus medialis (VMO) dysfunction

• Large Q-angle

• Hip internal rotation + adduction (medial collapse mechanism)

What is the “medial collapse” mechanism?

Weak hip abductors and poor pelvic control → femur rotates internally and adducts → patella tracks laterally → joint stress + pain

Why is Vastus medialis obliqqus dysfunction a problem in PFPS?

• VMO helps resist lateral pull on the patella

• If weak or delayed, patella tracks laterally

• Increased Q-angle worsens the valgus force

• Results in lateral cartilage overload and pain

What’s the controversy with VMO?

Some studies show no consistent difference in VMO activation between PFPS and healthy subjects — role still under research

What is the approach to treating PFPS?

• Initial phase: PEACE & LOVE / POLICE – rest, reduce swelling, pain management

• Repair phase: Correct biomechanics (muscle strength, length, control)

• Remodeling phase: Gradually increase activity level

Q: What does evidence say about exercise for PFPS?

• 2–4 sets of ≥10 reps daily for at least 6 weeks

• For athletes: higher reps (e.g. 3 sets of 20–30)

• Stretching + strengthening is key

• Orthotics may help with short-term pain

• Patellar taping/bracing: mixed evidence