Knee Pathology & Imaging

What are the compartments of the knee?

• Medial

• Lateral

• Patella femoral

What percentage of our weight goes through the medial compartment of the knee?

60%

What percentage of our weight goes through the lateral compartment of the knee?

40%

What are all the passive reasons that someone has atraumatic anterior knee pain?

• Patellofemoral pain syndrome

• Hoffa syndrome

• Chondromalacia

• PFJ OA

• Osgood-Schlatters

• Jumpers knee

• Sinding-Larsen-Johansson’s disease

• Pre patella bursitis

Anterior knee pain is more common in what populations?

• Females

• Active individuals

What are some common aggravating factors for someone with anterior knee pain?

• Descending stairs

• Squatting

• Prolonged sitting

What are the S/S of patellofemoral pain syndrome?

• Anterior knee pain when going up and down stairs

• Pain when sitting with knees flexed

• Pain with squatting

What is Hoffa syndrome?

Impingement of the infrapatellar fat pad between the patella and distal femoral condyle

What athletes most commonly develop Hoffa syndrome?

• Runners

• Cyclist

What is chondromalacia?

Softening/fissuring/fibrillation/destruction of articular cartilage on the posterior aspect of the patella that results in damage to the hyaline cartilage and sclerosis of the bone

What are the S/S of PFJ OA?

• Anterior knee pain

• Knee crepitus

• Swelling

• Pain on PFJ compression

• Stiffness after sitting

• Valgus knee deformity

• Reduced quad strength

• Morning stiffness that goes away after 30ish minutes

• Improvement in S/S with activity

What is the average age of someone who develops PFJ OA?

45 yrs

Load and joint position are ___ to one another

Interdependent

What are some possible causes of knee valgus?

• Gross weakness

  • Hip abductor weakness

  • Quad weakness

  • Hip extensor weakness

• DF limitation

• Hip flexion limitation

• Hyper-pronated foot

• Trying to avoid pain

Patellar tendinopathy/jumpers knee accounts for what percentage of knee diagnoses?

10%ish

What are the S/S of patellar tendinopathy/Jumpers knee?

• Pain localized to the inferior pole of the patella

• Swelling

• Load-related pain that increases with the demand on the knee extensors

• Pain with prolonged sitting, squatting, and stairs

• Movie goers sign

• Quad weakness

• Quad/hip flexor flexibility limitations

• Gluteal weakness

What sex is Osgood-schlatter’s most commonly in? What age range?

10-14 yr old males

What is Osgood-Schlatter’s disease?

Overuse of the patellar tendon which results in the epiphysis at the tibial tuberosity turning from cartilage to bone

What are the risk factors for developing Osgood-Schlatter’s disease?

• Male

• Sudden skeletal growth

• Repetitive activities like jumping and sprinting

What are the S/S of Osgood-Schlatter’s disease?

• Painful palpation of the tibial tuberosity

• Pain at the tibial tuberosity that worsens with physical activity or sport

• Increased pain at the tibial tuberosity with sports activity

• Bony protuberance at the tibial tuberosity

• Positive Ely’s test

• Isometric contraction of quad is painful

• Overgrowth at tibial tuberosity

• Alleviation with rest

• Pain with direct contact to tibial tuberosity

What is Sinding-Larsen-Johansson disease?

Necrosis of the inferior pole of the patella

What sex most commonly develops Sinding-Larsen-Johansson disease? At what age?

• Active males aged 9-17 yrs old

What are the S/S of Sinding-Larsen-Johansson disease?

• Pain worsens with exercise

• Limp after exercise

• Relieved with rest

• Positive Ely’s test

• Pain is at the inferior pole of the patella

What typically causes pre-patella bursitis?

Pressure from constant kneeling or a blow directly to the front of the knee

What are some potential causes of lateral knee pain?

• LCL injury

• Lateral meniscal injury

• PFC

• IT band syndrome

What is IT band syndrome?

Inflammation of the distal portion of the IT band at and around its insertion

IT band syndrome is the most common etiology of lateral knee pain in what populations?

• Runners

• Cyclists

What population rarely develops IT band syndrome?

Non-active population

IT band syndrome most often causes pain at what degree of knee flexion?

30°

What are the S/S of IT band syndrome?

• Tenderness to palpation of the lateral epicondyle of the femur

• Positive noble compression test

• Positive ober test

• Sharp, burning pain around the lateral joint line

What are some potential causes of medial knee pain?

• MCL injury

• Medial meniscus injury

• Plica

• Pes anserine bursitis

• Knee OA

What tendons form the pes anserine?

• Sartorius

• Gracilis

• Semitendinosus

What percentage of people with pes anserine bursitis will also have OA?

20%

What is plica?

A band of thick, fibrotic tissue that extends from the synovial capsule of a joint

If someone has plica syndrome, will they have symptoms during knee flexion or extension? Why?

Flexion cuz that’s when it gets pinched between the patella and femur

Where in the knee does articular cartilage most frequently break down?

• Medial femoral condyle

• Patellar articular surface

What are the S/S of a chondral pathology?

• Pain in the joint (especially with activity)

• Swelling and stiffness

• Clicking or locking

• Instability

• Noise, clicking, grinding

According to the ICRS grading system, what would a grade of 0 mean?

Normal with no defects

According to the ICRS grading system, what would a grade of 1 mean?

Nearly normal, just some superficial lesions

According to the ICRS grading system, what would a grade of 2 mean?

Abnormal surface with lesions of less than 50% depth

According to the ICRS grading system, what would a grade of 3 mean?

Severely abnormal surface with lesions greater than 50% depth

According to the ICRS grading system, what would a grade of 4 mean?

Severely abnormal surface with full-thickness osteochondral injury

Define an osteochondral pathology

Damage that involves that cartilage AND underlying bone

What is chondral delamination?

When a layer of cartilage peels away from the underlying layer

What is osteochondritis dissecans?

When a fragment of bone and cartilage detach from the underlying bone

What populations most commonly develop osteochondritis dissecans (OCD)?

Adolescent males

What is synovial chondromatosis?

A condition with multiple cartilage-like nodules in the joint

What is the cause of OCD?

Mild, repetitive microtrauma that often results from sports

Where does OCD most commonly develop (from most to least likely)?

1. Medial femoral condyle (66.2%)

2. Lateral femoral condyle (18.1%)

3. Trochlea (9.5%)

4. Patella (6%)

5. Tibial plateau (0.2%)

What are the S/S of OCD?

• Swelling

• Pain with activity

• Pain with palpation

• Vague crepitus

• Restricted movement range

• Joint effusion

• If lesions be unstable or bone be loose:

  • Catching, clicking, or locking

If caught early, how is OCD treated?

With rest

The likelihood of a degenerative meniscal tear decreases with age. True or false?

False, the likelihood increases with age

What is the peak onset of degenerative meniscus tears in males and females?

• Males: 41-50

• Females: 61-70

What are the S/S of degenerative meniscal tears?

• Pain with weight bearing

• Pain with rotation/pivot motions

• Swelling

• Clicking/popping

• Catching/giving out

Where is OA most commonly found in the body?

Tibiofemoral joint

The prevalence of tibiofemoral OA rises with what two factors?

• Increasing age

• Obesity

What radiographic changes are commonly seen in the knee with increasing age?

• Decreased joint space

• Osteophyte formation

• Varus or valgus deformity

What factors make someone at higher risk for symptomatic OA?

• Very high levels of physical activity correlated with external drivers over one’s life

• Sedentary lifestyle

• Diabetes/obesity

What factors put decreases someone’s chances of symptomatic OA?

• Moderate lvls of PA (ex: running) over the lifespan without external drivers

What are the S/S of tibiofemoral osteoarthritis (OA)?

• Stiffness after periods of immobility

• Crepitus

• Limited ROM

• Pain at end ROM

• Pain with weight-bearing

• Bow-legged

What is a baker’s cyst?

A synovial herniation the forms between the semi membranous and the medial gastrocnemius

A baker’s cyst is a symptom of what other conditions?

• OA

• Meniscus tear

What are the S/S of a baker’s cyst?

• Mass behind the knee

• Swelling

• Pain (dull or sharp)

• Tenderness

What are the S/S of biceps femoris/semimembranosus tendonitis?

• Pain in the back of the thigh (near knee or hip)

• Pain that worsens with activity

• Tenderness to touch

• Swelling

• Stiffness

What are some potential causes of biceps femoris/semimembranosus tendonitis?

• Overuse and repetitive strain

• Poor strength and flexibility

• Changes in training

What populations commonly develop popliteus tendonopathy?

Athletes who run/train on hills or banked surfaces (professional runners and triathletes)

What foot abnormality can result in popliteus tendinopathy? Why?

Hyper-pronation of the foot cuz it causes ER of the tibia which puts a strain on the popliteus

What are the S/S of popliteus tendinopathy?

• Acute pain in the posterolateral knee joint

• Localized swelling, redness, and tenderness to the lateral side of the knee at the popliteus insertion

What are the S/S of saphenous neuritis/gonalgia parenthetica?

• Pain in anterior or medial knee

• Deep thigh ache

• Paresthesias in saphenous nerve distribution

Saphenous neuritis commonly develops after what?

A trauma or surgery (70% of peeps with TKA develop it)

A MRI is the gold standard for assessing what structures?

• Ligaments

• Tendons

• Cartilage

• Menisci

When is a knee MRI indicated?

• Acute knee trauma with suspected internal derangement in the course of posttraumatic assessment

• Unexplained chronic knee pain

What are CT scans useful to assess?

• Bone fractures

• Bony abnormalities

What can a knee ultrasound be helpful in assessing?

• Soft tissue lesions

• Swollen bursae

• Joint effusion

• Superficial lesions

What is the typical MOI of a patellar dislocation?

Valgus or rotator force with slight knee flexion

What direction does the patella most commonly dislocate?

Laterally

What are the risk factors for patellar subluxation or dislocation?

• Q angle greater than 20°

• Excessive ER of tibia

• Increased IR of the femur

• Patella Alta

• Shallow trochlear groove

• Small, flat patella

What is the common MOI of a tibiofemoral joint dislocation?

High impact trauma (sports, fall from height, MVA)

What issues are commonly seen down the road after someone has a tibiofemoral joint dislocation?

• Drop foot

• Lymphedema

What kind of shape does an intercondylar fracture typically make?

“Y” fracture

What populations most commonly suffer distal femur fractures?

• Older females

• Young males

Most proximal tibial fractures occur between what ages?

40-60

What tibial plateau fractures most commonly?

Lateral plateau

What is the common MOI of a proximal tibial fracture?

Varus or valgus force with axial compression

What is a type I tibial fracture?

Split down a condyle

What is a type II tibial fracture?

Split with a depression

What is a type III tibial fracture?

Central depression

What is a type IV tibial fracture?

Split fracture, medial plateau (backwards y shape)

What is a type V tibial fracture?

Bicondylar fracture

What is a type VI tibial fracture?

Dissociation of metaphysics and diaphysis

what is the MOI of a patellar fracture?

• Direct trauma from a fall or blow

• Indirect trauma from tension forces (avulsion fractures)

What is the most common type of patellar fracture?

Transverse linear fracture through the mid-region of the bone

What is the MOI of a proximal fibula fracture?

• Direct blow

• Twisting injury to ankle

• Varus stress at knee

What other structures are commonly damaged with a proximal fibula fracture?

• Anterior tibial artery

• Peroneal nerve

• Interosseous membrane

What is a segond fracture?

An avulsion fracture on the lateral aspect of the tibial plateau at the insertion of the anterolateral ligament (ALL)

What fracture is highly indicative of an ACL tear and is commonly associated with anterolateral instability?

Segond fracture

What is the MOI of a segond fracture?

• Forced IR with a varus stress on the bone

What two bundles form the ACL?

• ANteromedial

• Posterolateral

What is main function of the ANteromedial bundle? What knee position makes it most taught?

• Provides most of the stability against anterior tibial translation

• Tightest in flexion

What are the main functions of the posterolateral bundle? What knee position makes it most taught?

• Provides medial-lateral and rotational stability

• Tightest in extension