Lecture 15: The Knee Part 2

What is the Anatomy of the Anterior Cruciate Ligament (ACL)?

Runs from anterior aspect of tibial plateau to the posterior medial aspect of lateral femoral condyle.

• 2 major bundles named for their attachment on the tibia:

• Anteromedial- Tighter in flexion

• Posterolateral- Tighter in extension

• Primary restraint to anterior tibial translation

• Greatest translation occurs at 20-30o

What are the ACL attachments?

• From anterior aspect of tibial plateau to posterior medial aspect of lateral femoral condyle.

• 2 major bands:

• Anteriomedial

• Posterolateral

What is the stabilizing role of the ACL?

Weaker of the two cruciate ligaments

• Functions to restrict posterior translation of the femur relative to the tibia during weight bearing

• Restricts anterior translation of the tibia during non-weight bearing

• Also limits excessive rotation of the tibia

• Secondary support for VALGUS and VARUS with collateral ligament damage

What is the Anatomy of the Posterior Cruciate Ligament (PCL)?

• The PCL originates on the lateral aspect of the medial femoral condyle and inserts posteriorly to intercondylar area of tibia

• 2 major bundles named for their attachment on the tibia:

• Anterolateral- Tight in Flexion

• Posteromedial- Tight in Extension

• Larger and stronger than the ACL

• Primary restraint to posterior tibial translation

• Greatest translation occurs at 20-30

What are the PCL attachments?

• From lateral aspect of medial femoral condyle

• Passes medial to ACL • inserts posteriorly to intercondylar area of tibia

• 2 bundles

• Larger anterolateral • Smaller posteriomedial

What is the Stabilizing role of the PCL?

• Stronger of the two cruciate ligaments

• Functions to restrict anterior translation of the femur relative to the tibia during weight bearing

• Restricts posterior translation of the tibia during non-weight bearing

• Also limits hyper- internal rotation • Secondary support for valgus and varus with collateral ligament damage

What is the meniscus?

• Once believed to be a useless remnant of intra-articular attachments

• Serve essential roles in maintaining knee function

• Stabilize knee by increasing concavity of tibia

• Shock absorption

• Full extension 45-50% of load

• 900 flexion 85% of load

• Compression facilitates distribution of nutrients

What is the medial meniscus?

• C- Shaped

• Larger radius of curvature

• Tight connection with capsule and MCL

• Poor mobility

What is the lateral meniscus?

• O Shape

• Smaller (tighter) radius of curvature

• Attached loosely to capsule and popliteal tendon

• Increased mobility

What is the meniscal Fixation?

• Significant disparity in the literature and between individuals

• The menisci are fixed in place and prevented from extruding by coronary ligaments and anterior and posterior transverse meniscal ligaments

• Deep portion of capsule attached to periphery of meniscus • Medial is thicker/tighter than the lateral.

What are the zones of the meniscal and there bloodflow?

• Red zone has good blood supply- outer 1/3

• Red-white zone- minimal blood supply- middle 1/3

• White -white zone is avasular

Subjective Knee Assessment - Overview

• Area of pain

• Medial, lateral, internal?

• Mechanism of Injury

• Varus or Valgus

• Contact or non-contact

• if contact, from where?

• if non-contact, decelerating, cutting, landing, etc?

• Sounds (i.e. " pop " or "crack")

• Continue to play/ able to WB ?

• Locking, giving way since?

Subjective Knee Assessment - Swelling

• Nature of any swelling - hemarthrosis?

• Bleeding into the joint • Typically occurs more quickly than synovial effusion/capsular swelling

• Noticeable swelling 2-6 hours post-injury

• >75% were ACL tears in adults

• Patellar dislocation next most common (young) followed by fracture and meniscal tears

• In pediatrics, suspect patellar dislocation

• Past history of trauma, surgeries

What are the Ottawa Knee Rules?

-Are age 55 or older

-Have tenderness at head of fibula

-Have isolated tenderness of patella

-Have inability to flex knee to 90 degrees

- inability to walk 4 steps

What is a patellar dislocation?

occurs when the patella moves out of its groove laterally onto/over the femoral condyle

What is the MOI of an Acute Patellar Dislocation?

• Forceful knee rotation (tibia ER/femur IR) +/- forceful quadriceps contraction •Knee usually near full ext. (out of trochlea) •+/- laterally directed force

Patellar Dislocation - Symptoms

• May report feeling knee "shift", "move" or "pop out"

• Pain++ until reduced

• Fast swelling

Patellar Dislocation - Signs

• "Loss of knee function (if still dislocated)

• Tenderness over medial border of patella

• Positive lateral apprehension test

• Need to R/O ACL...Why??

If the patella is dislocated, you should?

slightly flex the hip and slowly extend the knee. Usually the patella relocates. If it does not, do not force the patella medial.

There may be some associated fractures (back of the patella, lateral femoral condyle).

Lateral Collateral Ligament - The Facts

• LCL injuries are less common but more complicated secondary to the number of structures

• Usually varus loading + hyperextension

• Most contribution at 20-300 of knee flexion • May include ITB, lateral hamstrings and/or popliteus

Medial Collateral Ligament - The Facts

• 40% of all severe knee injuries involve the MCL, making it the most frequently injured knee structure

•Valgus force with or without rotation

• Often occur in isolation

Signs and Symptoms of Collateral Ligament Sprains

• Reports of pain over structure

• Swelling: Timing?

• ? minimal swelling LCL only- More if soft tissue injury

• Slow localized swelling medial side (grade 2+)

• Capsular effusion >8 hrs.

• Stress testing: In the same direction of MOI! • Valgus stress for MCL. Varus stress for LCL

• Grade I: pain with no laxity

• Grade II: pain with laxity. Distinct end point

• Grade III: Pain variable with gross laxityNo end point

ACL Injuries - The Facts

• Occurs with either contact or non-contact (60-80%) mechanism

• Usually during cutting or single leg landing

• May occur in isolation or in combination with other injury

• 75% sustain meniscal injuries

• 80% have bone bruise on lateral joint line or (Segond Fracture)

• 2-8 x higher injury rate in females

What are the MOIs of ACL Injuries?

1. Valgus after MCL- usually with contact

2. Deceleration/ internal rotation – non-contact 3. Hyperextension ?? In the texts, but can it really happen in isolation? NO

4. Quads Active – anterior tibial translat

ACL Injury: Quads Active Mechanism

• Main mechanism: -rapid deceleration -untoward landing

• Shoe - surface interface friction

• Anterior tibial dislocation by quads

ACL symptoms

• ~80% describe an audible "pop" or "crack"

• Can range from very painful to minimal pain • Usually unable to continue activity

• Hemarthrosis

• >75 % 1-6 hours

• May report instability or giving way

ACL signs

• Restricted movement • especially extension

• Lateral joint tenderness- often mistaken for LCL • 80% Lateral bone bruise or Segond fracture

• Positive Anterior Drawer & Lachman's Positive

• Graded like other ligaments

What are Posterior Cruciate Ligament Injuries?

• Strongest of the knee ligaments

• Only 1 in 10 cruciate injuries involve the PCL • ~60% include injuries to other structures

• Meniscal tears

• Usually sports injuries- but also common in MVAs

PCL Etiology/MOI

• Most common is a direct blow to upper portion of the tibia

• Fall on a flexed knee

• MVA-Dashboard injury or pre-tibial trauma

• Hyper-flexion

• Increased tension in anterior segment

• impinged between posterior tibia + intracondylar notch roof

• Hyperextension

PCL Signs

• Minimal swelling

• Posterior drawer test is most sensitive

• Graded like other ligaments

• Sag test will be positive

• Need to assess medial and lateral structures too!

What is Patellofemoral Pain?

PFP is characterized by pain in the peripatellar/retropatellar area that is aggravated by at least one activity that loads the patellofemoral joint during weight bearing on a flexed knee

What activities can aggravate patellofemoral pain?

• Pain walking down stairs

• Pain with squatting

• Pain following sitting for long periods

• Running, jumping, hopping

What is the % of physiotherapy (PT) visits for Patients with patellofemoral pain syndrome (PFPS)?

10-25%

What is the primary focus of evaluating overuse injuries?

• Primary focus of evaluating overuse injuries of the knee is to identify factors that may contribute to the condition

What is hypo and hyper pressure?

We strive for equal pressure distribution across the back of the patellae to ensure proper nutrition.

• If medial aspect of Patellofemoral Joint has hypo-pressure.

• If lateral aspect has hyper-pressure

- Results in cartilage rub and fibrillation

What are the Proposed Contributing INTRINSIC Factors for Patellofemoral Pain?

1. Lower chain alignment

2. Excessive pronation 3. Poor multi-plane lumbo-pelvic / Pelvo femoral control (core, gluteus medius)

4. Shortened muscles: hamstrings, ITB, calves and rectus femoris

5. Pull of quads

What is excessive pronation?

• Over pronation at the subtalar joint causes internal rotation of the tibia and delayed re-supination

• This affects screw-home mechanism as tibia doesn't externally rotate

• As such the femur must internally rotate more to get to extension

• Results in lateral pull on the patella

Tight muscles crossing the knee may cause altered function and/or pain...

- Quadriceps: Increased compression of the PF joint during physical activities

- Hamstrings: Antagonist to quadriceps- Will require increase quadriceps force production to overcome length issue - Iliotibial Lateral: influence on patella = Increased pressure over the lateral Band surface of the trochlear groove Must move over femoral condyle at 25-30 flexion

- Triceps Surae: Limit ankle dorsiflexion, which is often compensated for by excessive rotation of lower leg, altered Q-angle

What is Vastus Medialis Dysfunction?

• Sum of all 4 quads and tibial tendon are offset into valgus

• Theory that weak VMO will not be able to maintain alignment

• Slow

• Weak

• Altered line of pull

- Will cause abnormal pull on the patella... Overloading lateral side

Patellofemoral Pain Treatments

• Will follow the general rehabilitation protocol that we have outlined previously • Rehabilitation centers around identification and "correction" of intrinsic and extrinsic issues

• One of the most difficult musculoskeletal conditions managed by medical professionals.

• May be slightly different for each individual based on assessment findings

Patellofemoral Pain Treatment- Initial Phase

POLICE/PEACE&LOVE- Relative rest. Palliate pain, decrease swelling and identify training issues

Patellofemoral Pain Treatment-Repair Phase

Correct biomechanical issues as able.

• Look at muscle length, muscle strength and function

Patellofemoral Pain Treatment- Remodeling Phase

Slowly increase training frequency and intensity

Evidence Based Practice Tips for PFP Rehabilitation

• The current evidence supports prescription of daily exercises of two to four sets of ≥10 repetitions over a period of ≥6 weeks. • Consider higher repetitions of sets (i.e., three sets of 20-30 repetitions), for PFP patients who are involved in sports that include significant running and jumping • Conflicting research regarding knee braces and patellar taping • Some evidence for prefabricated foot orthoses with regard to reducing short term pain