Knee pathologies Flashcards by Sheryl O'Hare

Meniscal tears - What are menisci?

C shaped discs of fibrocartilage which only have a blood supply at the periphery
Look triangular on MRI (bowtie appearance)

Acts as a cushion between the femur and tibia
Shock absorbers

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Meniscal tears - which menisci (MEDIAL/LATERAL) is more likely to be torn?

Medial

as it is fixed and less mobile than the lateral meniscus
as the knee pivots more on the medial meniscus

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Meniscal tears - definition

Rupture of the menisci

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Meniscal tears - causes

Sporting injury

Getting up from a squat

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Meniscal tears - mechanism of injury

Twisting or turning quickly often while the foot is planted with the knee bent

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Meniscal tears - clinical features

Very localised pain (usually at medial joint line)
Sudden pain
Sharp pain
Locking sensation (patient can’t fully extend the knee)

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Meniscal tears - examination

Effusion (collection of fluid) develops by the next day
Joint line tenderness
Steinmann’s test

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Meniscal tears - investigations

MRI (to confirm clinical suspicion)

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Meniscal tears - management

Limited healing ability as they only have a peripheral blood supply
RICE
Physio
Consider arthroscopic meniscectomy for mechanical symptoms for irreparable tears / failed meniscal repair

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Meniscal tears - radial tear

Shouldn’t be painful

Won’t heal

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Meniscal tears - bucket handle tear

Meniscal tear flips out of normal position and physically jams in the knee. This prevents the knee from going straight, limits extension so the patient suddenly can’t fully extend the knee. This results in true knee locking

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Meniscal tears - acute

Sport injury due to twisting

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Meniscal tears - chronic

Degenerative tear due meniscus weakening with age

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Collateral ligaments (2)

Medial collateral ligament (MCL)

Lateral collateral ligament (LCL)

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MCL - function

Connects the bottom of the femur to the top of the tibia

Resists valgus stress - ie stops the knee from getting excessively knock kneed

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MCL - causes

Contact sports

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MCL - mechanism of injury

Direct ‘hit’ to the outer aspect of the knee which stretches/tears the MCL
Rupture results in valgus instability

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MCL injury - clinical features

‘Popping’ sound upon injury
Pain and tenderness along the inner aspect of the knee
Swelling
Locking/catching of the knee joint

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MCL injury - examination

Assess for joint effusion

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MCL injury - investigations

MRI scan

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MCL - management

Has a good blood supply so heals well
RICE 
Early motion
Physio
Put leg in brace

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LCL - function

Runs along the outside of the knee joint between the bottom of the femur and the top of the tibia.
Resists varus stress - ie stops excessive bow-leggedness

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LCL - mechanism of injury

Direct force trauma to the inside of the knee. This puts pressure on the outside of the knee and results in various stress
High incidence of common fibular nerve injury

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LCL injury - clinical features

Swelling of the outer aspect of the knee
Stiffness (locking)
Pain

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LCL injury - examination

Effusion

LCL injury - investigations

MRI scan

LCL - management

Doesn't heal well | A rupture needs urgent surgical repair

Cruciate ligaments (2)

Anterior (ACL) | Posterior (PCL)

ACL - function

Prevents abnormal internal rotation of the tibia, stops the tibia from rotating too much

ACL rupture - cause

High impact sports injury

ACL rupture - mechanism of injury

Twisting/turning the upper body laterally on a planted foot which causes the knee to give way. May lead to rotatory instability

ACL rupture - clinical features

``` 'Popping' sound Generalised deep pain all over knee Unable to continue activity Knee gives way on turning Can't weight bear ```

ACL rupture - examination

Bloody swelling accumulates in an hour (haemarthrosis) Anterior drawer test Lachman's test - excessive anterior translation of the tibia

ACL rupture - management

RICE Physio Analgesia Reconstruct ACL (surgery - carried out for instability, not pain) *Reconstruction is carried out if the patient is involved in intense sports

ACL rupture - prognosis

High risk of developing OA In later life 1/3 have no instability 1/3 can cope with instability 1/3 can't cope with instability and want to het back to high impact sport

PCL - function

Resists posterior subluxation of the tibia | Prevents hyperextension and anterior translation of the femur

PCL rupture - cause

Direct blow to the anterior tibia whilst knee is flexed | motorbike crash, dashboard from crash

PCL rupture - mechanism of injury

Direct blow to the anterior tibia on a flexed knee Hyperextension of the knee Posterior subluxation of the tibia

PCL rupture - clinical features

Instability | Pain

PCL rupture - examination

Posterior sag of the tibia (as the femur rides over the tibia) Swelling Brusing in the popliteal fossa

PCL rupture - management

If PCL is affected alone (unlikely) - no reconstruction | If other ligaments are affected - reconstruction required

Knee dislocation - definition

Rupture of at least 3 of the knee ligaments

Knee dislocation - cause | anterior, posterior, lateral

Anterior - severe hyperextension forces Posterior - high energy injury (dashboard injury) Lateral - rotational injury

Knee dislocation - clinical features

Immobility Swelling Gross deformity Knee pain

Knee dislocation - examinations

Assess ACL, PCL, MCL, LCL

Knee dislocation - investigations

X-ray | MRI

Knee dislocation - management

Emergency reduction Re-assess neuromuscular status Confirm reduction (by doing a repeat X-ray) Operative: ligament reconstruction

The patella always dislocates medially/laterally?

Laterally

Patella dislocation - who gets it

Females | Adolescence

Patella dislocation - risk factors

Ligamentous laxity | Genu valgum

Patella dislocation - clinical features

Obvious deformity | Patella dislocated laterally

Patella dislocation - examinations

May get a lipo-haemarthrosis

Patella dislocation - management

Reduction Splint Physio

Knee replacement - who gets it

Older patients | - where conservative management is no longer effective

Knee replacement - younger patients

Avoid young, active patients Higher likelihood of failure Likely to require revision surgery which is less effective

Extensor mechanism rupture - constituents

``` Patella Tibial tuberosity Patellar tendon Quadraceps tendon Quadriceps muscle ```

Extensor mechanism rupture - younger patients

Patellar tendon rupture

Extensor mechanism rupture - older patients

Quadriceps tendon rupture

Extensor mechanism rupture - predisposing factors

Chronic steroid use Quinolone antibiotics Diabetes Hx tendonitis

Extensor mechanism rupture - examination

Unable to straight leg raise | Obvious palpable gap

Extensor mechanism rupture - investigations

X-ray

Extensor mechanism rupture - management

Tendon-tendon surgical repair | Reattachment of tendon to patella

Osteochondritis dissecans - definition

Lack of blood supply to an area of bone causes it to break off from the main bone

Osteichondritis dissecans - who gets it

Adolescents

Osgood schlatters disease - definition

Inflammation in the tibial tuberosity

Osgood schlatters disease - cause

Active adolescent boys | Growth spurts

Osgood schlatters disease - clinical features

Pain at tibial tuberosity

Bakers cyst - definition

Out pouching of the fluid that forms a lump behind the knee

Bakers cyst - management

Nothing

Septic arthritis - definition

Inflammation of the joint space caused by infection

Septic arthritis - causative organism

Staph aureus

Septic arthritis - clinical features

Similar to gout - red hot, swollen, painful joint Usually only one joint is affected

Septic arthritis - investigations

Joint aspirate - if frank pus is aspirated then septic arthritis is diagnosis X-ray - pus fills joint space

Septic arthritis - management

Debridement of pus and fluid Once causative organism is confirmed.... IV antibiotics