BPK 241 Lecture 7

Knee Joint types

• Anatomically = synovial (fluid, sacs)

• Functionally = hinge (one phase of movement)

• Physiologically = Rotation/ rolling & gliding

Knee Bones

• Femur

• Tibia

• Patella

Knee Articulations

• Tibiofemoral - Femur & tibia

• Patellofemoral - Patella & femur

Knee Stability

• Capsule

• Ligaments

• Menisci

• Muscles

• Tendon

Knee Capsule

• Extensive & Redundant

• Resists hyperextension

• Provides rotational stability

• Swelling accumulate at front of knee from capsule space

Extracapsular ligaments

• Medial collateral (MCL)

  • Short inner, long outer fibres

  • Medial epicondyle (push side of knee); where is originates

  • prevent knee from force going inward

• Lateral collateral (LCL)

  • Attaches to femur and head of fibula

  • prevent knee outward

Intracapsular ligament

• Anterior cruciate (ACL)

  • Anterior tibia, then up, back, out to medial surface of lateral epicondyle

  • Prevents anterior displacement of tibia on fixed femur, hyperextension

  • prevent femur posteriorly, prevent tibia anteriorly

• Posterior cruciate (PCL)

  • Posterior tibia, then up, forward, in to lateral surface of medial condyle

  • Prevents posterior displacement of tibia on fixed femur

  • prevent femur forward, prevent tibia backward

Knee menisci

• Fibrocartilage

• Medial and tibial

• Attached to tibial plateau

  • Tough fibre material

  • cushion for shock observes

  • acts as a sponge, soaks synovial fluid and releases it for blood supplly

Red zone of Menisci

1/3 Outer

Pink zone of Menisci

Middle 1/3 - terrible blood supply

White zone of Menisci

Inner 1/3 - No blood supply, can’t heal itself

Menisci & Coronary ligament

• Attached to tibial plateau

• Attached to capsule by coronary ligaments

• Provides cushioning & stability

• Increases synovial fluid circulation

Knee Muscles

• Quadriceps femoris (extend the knee, helps PCL from tibia moving backwards)

  • Rectus femoris (o=ilium at AIIS)

  • Vastus medialis (o=femur)

  • Vastus intermedias (o=femur)

  • Vastus lateralis (o=femur)

    • All insert by quadriceps tendon and patellar tendon (patellar ligament) on tibial tuberosity

    • Function: extension of leg at knee

Hamstrings

• o = ischuim

  • Biceps femoris

  • Semimebranosis

  • Semitendinosis

    • insert onto medial tibia

    • Bicep femoris inserts on head of fibula

    • flex lower leg on thigh at knee

    • Extend thigh on trunk at hip

    • Help a little with hip extension and help ACL from tibia moving forward

Tensor Fascia Latae (TFL)

• o = ischium

• Inserts on tibia and into fascia of the thigh (via iliotibial band)

• Helps flex and abduct thigh on trunk at hip

• Adds to lateral stability of knee

Gracilis

• Same origin and insertion as semimebranosis and semitendinosis

• Assists with knee flexion

Knee Bursae

• Prepatellar

• Suprapatellar (and fat pad)

• Infrapatellar (and fat pad)

  • Decrease friction over the bone

  • most common in chronic onset injury

Knee movements

• Flexion & extension

• Gliding of condyles on plateau and menisci

• Rolling (posterior) & gliding (anterior) happening at the same time when flexion and extension occurs

Locking Mechanism

• Medial condyle is larger than lateral

• Internal rotation of thigh AND/OR rotation of lower leg completes full extension at knee (locking)

• Possible medial meniscal distortion

  • Locked knee: ACL taught, PCL taught, knee joint taught - forces femur in internal rotation & tibia in external rotation

  • Unlocked knees: Pull femur in external rotation, tibia in internal rotation

Knee Assessment

• Hx: What happened, where

• PHx: priory injury? Rehab? Ongoing?

• SSx:

  • Unstable on knee

  • “snap”, “pop”

• Examination

  • Observation

    • Limp, instability

    • Swelling (acute or delayed - 24?)

    • Gait analyses

• ROM:

  • Functional tests - compare sides

  • Thigh circumference - serial

    • Sends signal to thigh to shut off if severe

  • Palpation - be systematic

Knee Alignment Deviations

• Patellar Malaligments

• Q- Angle

Observation of Knee alignment deviations

• Genu Valgrum (knocked kneed)

  • Increase Q-angle

• Genu Varum (bow legged)

  • Decrease Q-angle

• Genu recurvatum

  • Hyperextension

• Genu antecurvatum

Weight Bearing Functional Assessment

• Gait

• Cycle

• Single leg squat

• Thessaly - menisci

• Duck walk (Childress Test) meniscus

• 2 legged hop

• Single leg hop

• Test on strength, distance

Knee Assessment ROM

• Flexion/Extension

  • Active

  • Passive

  • Resisted (strength)

Extacapsular ligaments: LCL/ MCL

• Valgus stress test

• Varus stress test

Intracapsullar Swelling Tests

• ACL, MCL, Meniscus (medial)

• Patellar compression - Ballottement

• Swipe (sweep) test

  • Pushing down on patella

  • force swelling of knee from medial to lateral side of knee

Knee Assessment - ACL

• Anterior drawer (injured vs uninjured)

• Lachman’s (pulling tibia forward)

• Pivot shift

• MRI accuracy for diagnosis of ACL injury 95% or >

Knee Assessment - PCL

• Posterior sag

• Posterior drawer

Knee Assessment - Meniscus

• Apley’s compression (bent knee position “forced knee rotation”)

• McMurray’s

• Joint line tenderness

Knee Contusions

• Direct blow

• Worse if muscle relaxed

• SSx:

  • Pain, tenderness

  • Swelling (circumscribed)

  • Discolouration

  • Limp

• Tx:

  • Crutches, ice

  • POLICE for 2 days

  • ROM, padding - return to sport

  • Physiotherapy and rehabilitation

• N.B. No massage, no heat directly over bruise (myositis ossificans - surplus of calcium forced)

Bursitis

• Direct blow or kneeling

• Overuse

• SSx:

  • Inflammation (five stages)

  • Tenderness

  • Painful on knee extension if infrapatellar or suprapatellar

• Tx:

  • POLICE, padding, NSAIDs

  • Heat, physiotherapy, rehabilitation

  • Early aspiration if acute, traumatic, drain fluid from bursae

• Complications

  • Chronicity, recurrence, infection

Sprains

• Direct blow (e.g. valgus anterior)

• Torsion or hyperextension

• Worse if foot is fixed (planted)

1st degree Sprain

• Mild pain, mild swelling

• NO Snap or Pop

• NO limp, NO effusion, NO increased laxity

  • Tx: POLICE, physiotherapy, brace

2nd Degree Sprain

• Pain, tenderness, “snap”

• Swelling (and effusion if intraarticular)

• Limp

• Increased laxity with firm endpoint

• Tx: as for 1st degree, plus see MD. Longer recovery period

3rd Degrees

• Complete rupture of ligament(s)

• SSx:

  • More pain, tenderness, “snap”

  • Marked swelling, effusion

  • Unstable or won’t bear weight

  • Marked increased laxity, soft endpoint

• Tx:

  • NPO

  • Stabilize and transport to hospital

  • Will need brace ± or surgery

  • Follow with extensive physio, rehab

Meniscal tears

• Mechanisms

  • Torsion

  • Hyperextension

• SSx:

  • Acute

    • Pain, tenderness

    • Effusion

  • Chronic or acute

    • Locking or buckling

    • Intermittent pain, swelling, effusion

    • Positive McMurray’s, Apley’s tests

• Tx:

  • Physiotherapy

  • Arthroscopic repair or excision

  • Exercise

Capsular tears

• Mechanisms

  • Torsion

  • Hyperextension

• SSx:

  • Pain

  • Swelling?

  • Tenderness

  • May cause rotary instability

  • Mimics torn meniscus or tendon injury

• Tx:

  • Rest, physiotherapy, rehabilitation

  • Surgery if symptoms persist

Patellofemoral Pain Syndrome

• Pain around patellofemoral joint

• Related to abnormal tracking of patellae in femoral groove

  • Causes of abnormal patellar tracking can include: genu valgrum, external tibial torsion, overpronation, greater than normal Q angle

Chondromalacia Patellae

• Softening and deterioration of cartilage on back of patellae

• SSx: Pain walking up or down, running, squating

• Tx: Conservative (POLICE, NSAIDs, activity modification, strengthening, orthotics)

  • Surgery is last resort

Patellofemoral Stress Syndrome

• Lateral tracking of patellae in femoral groove

• Tight lateral musculature, weak hip abductors/ stabilizers

• SSx: Pain lateral patellae, crepitis with patellar compression

• Tx: POLICE, avoiding aggravating activities, strengthening VMO over VL. Stretching lateral soft tissues, McConnell taping/bracing

Unhappy triad

• Structures damaged

  • ACL Tear

    • Positive anterior drawer Lachmann’s test, pivot shift

    • Effusion

    • “snap”

  • MCL tear

    • Valgus instability, point tenderness

  • Meniscal tear

    • Tenderness

    • Locking or buckling

  • Capsular tear

• Tx:

  • Reconstructive surgery

  • Brace, physio, rehab

• NB. Effusion? To hospital ASAP

Osteochondritis dissecans

• Damage to cartilage and subchondral bone

• Most commonly in knee, medial femoral condyle 70% of time

• Causes: hereditary, traumatic, vascular

  • Progression: softening of cartilage

  • Early cartilage separation from bone

  • Partial detachment of cartilage

  • Osteochondral separation with loose bodies

ACL - Post Surgical Rehab

• Quadriceps/ hamstrings activation

• ROM focusing on full extension

• 3 to 4 months post surgery - proceed with caution

• Closed kinetic chain → Open kinetic chain

• Strengthening - hamstrings and quadriceps balanced

• 6 months in - increase loading, jogging, running

• Neuromuscular training

• Return to sport - education/ technique modification

• Return to sport - functional testing

• Brace?

Prevention of ACL injury: FIFA 11

• ROM

• Agility

• Strength test

• Dynamic warm up

Screening for Risk of Knee Injuries

Drop vertical jump test