Knee Complex Lecture

functional role of the knee

accepts the load, guides it, supports it, and attenuates it

where do problems arise from at the knee

what happens above and below it

Two joints in the knee

patellofemoral

tibiofemoral

screwhome mechanism

full knee extension, tibia externally rotates

what structures are intra-articular and extrasynovial

ACL and PCL

ACL function

primary restraint to anterior translation of the tibia relative to the femur

secondary restraint to medial and later rotation in NWB position

ACL innervation

tibial nerve

blood supply to ACL

main: middle geniculate artery

distal portion: branches of lateral and medial inferior geniculate artery

PCL function

provides 90-95% of the total restraint to posterior translation of the tibia on the femur

when are the posterior lateral fibers of ACL increasingly taut

in extension

when are the anterior medial fibers of the ACL taut

flexion40-60

when is there minimal tension of the posterolateral fibers of the ACL

40-60 degrees knee flexion

when is the PCL tight

knee flexion

factors associated with non-contact ACL injury

strong activation of quads over a slightly flexed knee

marked valgus collapse of the knee with knee in ER

tibia IR as the femur ER

excessive hyperextension while foot is planted on the ground

when are the anterior fibers of the medial collateral ligament taut

flexion

when are the posterior fibers of the MCL taut

in extension

LCL function

resist varus forces

when is the LCL most taut

25 degrees of flexion and full extension

medial meniscus shape

semi-lunar/C-shaped

which meniscus is larger and thicker

medial meniscus

tibial plateau contour under medial meniscus

concave

tibial plateau contour under lateral meniscus

convex

which portion of the medial meniscus is wider

the posterior portion

lateral meniscus shape

O-shaped

what attaches to the lateral meniscus

ligaments of Humphrey and Wrisberg

movement of menisci during knee flexion

posterior translation

movement of menisci during knee extension

anterior translation

movement of menisci during tibial rotation

stay with the femur

movement of menisci during tibial IR

medial meniscus translates anteriorly

lateral meniscus translates posteriorly

movement of the menisci during tibial ER

medial meniscus translates posteriorly

lateral meniscus translates anteriorly

Q angle points

ASIS to mid-point of the patella

long axis of the patellar tendon from tibial tuberosity through the mid-point of the patella

normal Q-angle for men

8-14

normal Q-angle for women

15-17

abnormal Q-angle

>20 degrees

medial pain indicates what potential structures

meniscus

MT ligament

MCL

pes anserinus bursa

MCL bursa

semimembranosus

saphenous nerve

posterior pain in the knee indicates what potential structures

meniscus

joint capsule

tendinopathy

lateral pain indicates which potential structures

meniscus

MT ligament

LCL

biceps femoris

popliteus

ITB

peroneal nerve

anterior pain in the knee indicates which potential structures

meniscus

MT ligament

extensor mechanism

PFJ

patella

TFJ

bursitis

fat pad

patellofemoral pain is aggravated by

sitting, climbing stairs, inclined walking, and squatting

influencing factors of patellofemoral pain

anatomic variance

gender

tibial rotation

subtalar joint position

femoral rotation

motor control issues

hip weakness

how does external tibial rotation impact the Q-angle

it decreases

how does internal tibial rotation affect the Q-angle

it increases

how does pronation affect tibial rotation

it causes internal rotation

how does femoral anteversion affect the Q-angle

it increases it

what is typically visible with the step down test

dynamic knee valgus

PFJ tracking problems are due to

static and dynamic structures insufficiently supporting the PFJ

what is goal of intervention with PFJ tracking problems

restore balance of force production of the medial and lateral stabilizers of the PFJ

establish the functional control of the knee extensors

increases hip stability through abductors, extensors, and external rotators.

PFP CPG for diagnosis

reproduction of retropatellar or peripatellar pain during squatting, stair ascension, and/or descension

presence of retropatellar or peripatellar pain, reproduction of pain with loading the PFJ in a fixed position, excluding all other conditions that cause anterior knee pain

PFP CPG with strong evidence for interventions

hip and knee combination exercise therapy

prefabricated foot orthoses for >normal pronation for short term (up to 6 weeks). Combine with exercise

should not use dry needling

should not use manual therapy in isolation

PFP CPG with moderate evidence for interventions

tailored patellar taping in combination with exercise therapy

should not prescribe pf knee orthoses

should not use EMG biofeedback during quadriceps exercise or visual feedback for LE alignment during hip/knee exercises

should not use US, cryotherapy, phonophoresis, iontophoresis, e-stim, and ther laser

PFP CPG with weak evidence for interventions

gait retraining

acupuncture

PFP CPG from expert opinions for interventions

BFR with high-repetition knee exercise therapy

patient education on load management, body-weight management, exercise therapy compliance, biomechanics of PFJ overload, kinesiophobia, and treatement options

articular cartilage defects

read surgical interventions in Dutton

arthroscopic lavage and debridement

microfracture

autologous osteochondral mosaicplasty grafting

autologous chondrocyte implantation

osteochondral autograft transfer

osteochondral allograft transplantation

what is rehab of articular cartilage defects based on

healing stages

most common cause of disability in the US

tibiofemoral osteoarthritis

tibiofemoral osteoarthritis

wear and tear or degenerative related to activity

clinical findings for tibiofemoral osteoarthritis

Hx: pain with WB activity

Inspection: swelling, warmth

AROM/PROM: loss of motion in capsular pattern

RROM: possible pain due to joint compression, possible weakness if there is atrophy due to inactivity

conservative management for tibial osteoarthritis

medical: NSAID’s, cortisone

therapy: pt education on weight loss, therapeutic exercise for quadriceps strengthening, techniques to improve neuromuscular function, modalities, shoe inserts/orthotics, manual therapy as an adjunct to exercise

Read TKA section in Dutton about tibiofemoral osteoarthritis

how is patellofemoral osteoarthiritis diagnosed

through correlation of patellofemoral pain and radiograph

chondromalacia

softening on the posterior aspect of the patella

two types of patellofemoral osteoarthritis

surface degeneration

basal degeneration

Grade 1 patellofemoral osteoarthritis

closed diaphysis

intact joint surface that is spongy

softening is reversible

blister on articular surface

Grade 2 patellofemoral osteoarthritis

open diaphysis

fisures that may not be obvious initially

Grade 3 patellofemoral osteoarthritis

severe exuberant fibrillation or crabmeat appearance

Grade 4 patellofemoral osteoarthritis

fibrillation is full thickness and erosive changes down to the bone, essentially osteoarthritis

conservative intervention for patellofemoral osteoarthritis

correct imbalances in flexibility and strength

occasional surgical realignment

what type of lesions are not painful

chondral

arthrofibrosis cycle

dense proliferative scar formation intra and extra articular leads to limitation of motion

potential sites of arthrofibrosis

parapatellar recess

suprapatellar recess

intercondylar notch

articular surface

how is arthrofibrosis diagnosed?

via exclusion

mechanical causes of arthrofibrosis

loss of articular congruency

substantial effusion

extensor or flexor mechanism interrupted

ACL graft placement

clinical presentation of arthrofibrosis

capsular pattern of restriction

crepitus and weakness of quadriceps

knee is often held in flexion causing tightness in the posterior joint cpasule and hamstrings

spring-like end feel due to thickened, inflamed, or scarred peripatellar tissue

intervention for arthrofibrosis

ROM exercises and specific soft tissue stretching

gentle manipulation under anesthesia

closed manipulation or aggressive manipulation may damage tissues such as tearing, fracture, chondral damage, tendon rupture, or CRPS

arthroscopic debridement

factors of tibiofemoral instability

type of trauma

laxity leads to degeneration through displacement and shear

patient presentation of tibiofemoral instability

giving way

locking or catching followed by pain

Exam findings for tibiofemoral instability

AROM/PROM hypermobility

RROM: possible pain

Special tests: (+) instability tests

intervention for tibiofemoral instability

muscle strengthening

passive restraints

neuromuscular re-education

proprioceptive re-education

what guides the intervention for tibiofemoral instability

the direction of laxity

how many athletes are diagnosed with ACL injuries per year

250,000

intrinsic factors for ACL injury

narrow intercondylar notch

weak ACL

overall joint laxity

LE malalignment

extrinsic factors of ACL injuries

quadriceps/hamstring imbalance

abnormal muscle control

shoe-to-surface interface

athlete’s playing style

why are women 2-8 times more likely to tear their ACL

anatomic alignment/structural differences

femoral notch

joint laxity

hormonal influence

ACL size

muscular strength and muscle activation patterns

midsubstance ACL tear

tear in central ligament as opposed to the insertion site of the ligament

Avulsion fracture with ACL tear

young athletes

injuries in youth lead to

predisposition to degenerative conditions

associated injuries with ACL tears

MCL, medial meniscus, deafferentiation, degenerative changes

mechanism of injury in sports for ACL tear

valgus force

femur ER with extension with fixed foot

hyperextension

what percentage of ACL tears are non-contact

70%

H:Q ratio that puts a patient at risk for higher incidence of ACL tear

<75% and bilateral HS difference of >15%

patient history of ACL tear

knee popping out or giving way

decrease in functional stability