Knee Flashcards
What percentage of knee injuries are ligament injuries?
40%
What percentage of ligament knee injuries are ACL?
50%
What healing capacity has the ACL got and why?
Poor due to its limited blood supply
Cant repair itself
Why are the ACL injury rates higher for females compared to males?
Increased Q angles
Ligaments have greater laxity
What is the origin and insertion of the ACL and its direction?
Origin: Antero-medial intercondylar area of tibia
Insertion: Posterior lateral femoral condyle
Direction: From tibia goes laterally and posteriorly (30 degree angle)
What are the 2 bundles of the ACL?
- Antero-medial bundle - taut at full flexion
2. Postero-lateral bundle - taut at full extension
What are the main function of the ACL
Reduces anterior tibial translation
Restricts foot abduction and hyperextension of the tibia
Limiting knee IR
Proprioceptive feedback
After ACL reconstruction surgery, what do people struggle with the most?
Proprioception
ACL loses its proprioceptive fibres
What are the subjective signs of an ACL rupture
Popping sensation
Traumatic knee injury
Instability and giving way - secondary to pain, eccentric loading of the knee (going downstairs)
Joint pain
Haemarthrosis
Mechanism of injury - non-contact, pivot, hyperextension, landing in extension, foot planted, valgus collapse
What is the mechanism of an ACL injury?
Non-contact
Pivot
Hyperextension
Landing in extension
One step-stop deceleration
Can be contact - tackling from behind (side), valgus collapse
Describe that they cant anticipate the event or loss of concentration
Explain valgus collapse
Fixed foot and patient goes to change direction
Ankle eversion
Knee abduction (distal tibia goes away from the midline)
Femoral adduction
Forced medial opening of the knee
30 degree knee flexion
Name the special tests for the ACL
Lachmans
Anterior Draw
Prone Lachman’s
What has the literature stated regarding the sensitivity of diagnosing an ACL injury?
If you get a good subjective information and objective information = almost 100% sensitivity
Mostly done on the chronic stage of injury
What is the best test for acute ACL injuries?
Lachmans = High sens, high spec and high intra-tester reliability
What is the best test for chronic ACL injuries?
Anterior drawer = high sens and high spec
Lachmans also has high sens, high spec and intra-tester reliability
How do you grade ACL laxity?
1 (1mm to 5mm)
2 (6mm to 10mm)
3 (>10mm)
Difficult to feel the difference
What type of physio is the anterior drawer good for?
Inexperienced physios
Why should you not do the pivot shift test?
Can make patients nauseas and they do not like it
Brutal test usually used by surgeons when patients are under anaesthetic
What type of patient is the prone lachmans good for?
Large patients
Should you use imaging for ACL injuries?
Alot of joint line pain = x-ray to rule out bony injuries
MRI has similar diagnostic accuracy to good subjective and objective assessment
MRI before surgery
What is the most common knee pathology?
NICE 2014
Knee OA
How do you diagnose knee OA?
Diagnosis of exclusion - cant find a pathology then send patient for an x-ray
X-ray would confirm knee OA through the Kellgren & Lawrence classification
What is the Kellgren & Lawrence classification?
How to diagnose and grade Knee OA on an x-ray
Joint space narrowing, osteophytes, sclerosis and bone end deformity
Grade 0 - None
Grade 1 Doubtful
Grade 2 Minimal
Grade 3 Moderate
Grade 4 Severe
What is the problems with x-ray and knee OA?
Poor correlation between imaging and pain experience
What is knee OA symptoms, level of pain and level of disability potentially linked to?
Psychosocial factors and central sensitisation
How can you diagnose someone with knee OA?
NICE 2014 Guidelines
Atraumatic knee pain
Activity related joint pain and
> 45 years old and
Morning joint-related stiffness that does not last longer than 30 minutes
How can you manage someone with knee OA with yellow flags?
Reassure that the person does not need an x-ray and how these poorly correlate with pain experience
Educate how increasing strength and balance can reduce pain
Encourage patient to be as active as possible
If conservative management does not work = x-ray to confirm
Just get an x-ray if patient is so anxious and it will help management
What is a patient reported outcome measure for knee OA?
WOMAC
3 Parts - Pain, stiffness and function
high sens and high sens
Pain and stiffness have high ceiling effects but function has low ceiling effect
Low ceiling effect = cant measure higher levels of function
What are the subjective indicators of PFPS?
Nunes et al 2013/Cook et al 2012
Diagnosed through exclusion
Pain during squatting - high sens, moderate spec (most useful
Pain during stair climbing - good sens, moderate spec
Pain during prolonged sitting or flexion - good sens, moderate spec
Pain location - U Shape <5 years
Usual bilateral pain - biomechanics or central sensitisation?
What are the special tests for PFPS?
Clarke’s sign - good spec, low sens
Apprehension test - also used to assess patella dislocation
Patellar tilt - high spec, low sens
What is a positive patellar apprehension test?
Patient become apprehensive or feels a sensation of the patella going to dislocate
Patient may activate quads to stop movement of the patella
Laxity alone = not a positive test
Good spec for patella dislocation
What force do you apply to the patella with Clarkes sign?
Compression and distal - then ask patient to contract quads
What other functional movements may someone with PFPS find painful?
Running
Hopping
Pain with step down
What muscles are important with PFPS?
Hip musculature
Weak glutes = IR of Femur = lateral mal-tracking of the patella
Why is PFPS multifactorial?
Weakness of hip musculature (Glutes), knee musculature (quads/hamstrings) and poor foot biomechanics (weak tib post)
Medial collapse
Explain the anatomy of the meniscus
Fibro-cartilaginous plates that sit on top of the tibial plateau
Medial and lateral
Medial is more stretched out C-shaped
Lateral is more rounded C-shaped with larger surface area
Attached together by the transverse ligament
Attached to the tibia plateaus by the coronary ligaments
Thick peripheral border and attaches to the joint capsule
Divided into the anterior horn, body and posterior horn
Which of the menisci get injured (50%) with an ACL injury and why?
Medial meniscus - close to the origin of the ACL
What ligament fuses with the medial meniscus?
Deep fibres of the MCL
Commonly injured together
Explain the blood and nerve supply of the menisci
Poor blood supply - only periphery and horns are vascular
Nerve supply is the same as the vascular supply (periphery and horns)
Where does the menisci get there main source of nutrition from and what is the implication for this?
Synovial fluid
Takes the meniscus a long time to heal
Where are mechanoreceptors found in the meniscus?
Horns = proprioceptive feedback and joint position sense
What are the subjective indicators of a meniscal tear?
Logerstedt et al., 2018; Nie et al., 2011
Mechanism of injury:
Twisting injury with foot planted - weight bearing
Traumatic
Tearing sensation at time of injury
Symptoms:
Localised pain - patient will point to specific area, usually the joint line
Delayed effusion (6-24 hours post injury)
Clicking
Catching or locking
Feeling of giving way - Associated with pain
Pain with forced knee hyperextension - Anterior Horn
Pain with forced max knee flexion - Posterior Horn
How do you differentiate between an isolated meniscus injury and a meniscus injury with ACL injury?
Rate of swelling
What is it important not to do when asking about patients symptoms especially with potential meniscus injuries?
Do not lead the patient - try and get them to describe as many symptoms as they can
Meniscus symptoms can be similar to non-specific knee pain and other knee injuries
What are the special tests for meniscal injuries?
Joint line tenderness
McMurrays
Apleys
Thessalys
How accurate is special tests for diagnosing meniscal injuries?
Hegedus et al., 2017
Joint line tenderness, McMurrays or Apleys alone are not accurate to diagnose meniscal tears
Specificity generally better than sensitivity for all 3 tests
Joint line tenderness has the best sens and spec but can get a lot of false positives
What are the advantages and disadvantages of the Thessaly test?
Advantages - Function
Disadvantages - cant standardise the degree of knee flex and amount of rotation
High Spec but moderate sens
How should you order the special tests for meniscal injuries and why?
- Joint line tenderness
- McMurrays
- Thessalys
At least 2 are positive = meniscal tear likely
At least 2 are negative = meniscal tear unlikely
Irritability
What are the limitations of meniscal testing?
Variations in the literature for what is a -ve and +ve test
Tests done in a variety of different ways and this isnt described in the literature
Literature is of poor methodological quality and have high bias
Why are there limitations to meniscus testing?
Due to the variety of tears
What are the different types of meniscus tears?
Bucket handle tear
Radial tear
Parrots beak tear
Horizontal tear
Root tear
Degenerative tear
What causes degenerative meniscus tears?
General wear and tear e.g. walking, hereditary, footwear, occupations that involve patients kneeling a lot (plumbers)
What type of meniscus tear will you get a true locking and a positive test for all special tests?
Bucket handle tear
Where in the meniscus could a patient get a tear but not get any symptoms and why?
Centrally (radial tear) as there is no nerve supply
Although this may not heal due to poor vascular supply
Why may a patient get symptoms if the tear is in the area of the meniscus with no nerve supply?
Scan that shows tear = patient becomes anxious = increase in pain
When should you image a meniscus tear?
Bucket handle tears as they require surgery (true locking)
NICE guidelines?
Why does lateral meniscus tear injuries cause more symptoms and take longer to heal?
More load goes down through the lateral meniscus (70%) = more pressure
The lateral joint surface does not come together very well compared to the medial joint surface
Less surface area = more pressure
What is the anatomy of the medial collateral ligament (MCL)?
2 components
Superficial fibres
Superior to inferior
As the fibres go over the medial joint line it spreads out
Deep capsular fibres is continuous with the medial meniscus
If meniscus is injured means that the deep capsular fibres are involved
Bursa between superficial and deep fibres
What is the function of the MCL
Primary medial knee stabiliser
Limit valgus stress
Which hamstring is connected with the MCL, how and why is this important?
Semimebranosus tendon fuses with the superficial fibres of the MCL
Injury to one of these structures usually causes injury to the other
Semimem tendon injury e.g. tendinopathy
What is the mechanism of injury of an MCL injury?
Foot planted
Valgus knee loading
External rotation or. combined cutting movement that opens the joint
Usually accompanied with an external force (how to differentiate from an ACL injury)
In football when do most MCL injuries occur?
Last 10 mins
Strong association with fatigue - hamstrings
How you diagnose an MCL injury?
History Trauma by external force to the leg Rotational trauma Valgus knee loading Planted foot
Physical exam
Laxity and pain with valgus stress test 30 degrees knee flexion
This combined method has moderate sens and high spec
At what knee angles do you test for the valgus stress test and why?
0 degrees - laxity and pain means an ACL injury
30 degrees - laxity and pain means an MCL injury
Laxity and pain on both = ACL and MCL injury
What is the anatomy of the PCL?
More vertical than the ACL and posterior of the midline
PCL has a lot of surrounding support that the ACL does not have
Goes beyond the joint capsule
2 components
Anterior-lateral
Posterior-medial
What are the signs and symptoms of a PCL injury?
95% of people with PCL injuries will have associated injuries
Vague, non-specific symptoms e.g. discomfort that is difficult to isloate
Mild/mod non-specific pain posterior knee (especially when squatting/kneeling/going downstairs)
Instability
What is the mechanism for a PCL injury?
Anterior tibial blow injury with knee slightly flexed (dashboard injury)
Fall on flexed knee with foot in PF
Violent hyperextension of the knee joint
What are the special tests for the PCL?
Posterior drawer test
Sag sign
Variety sens and poor data on spec
What are the key elements of performing the posterior drawer test?
Need to bring tibia as far forward as possible - if person has no PCL the tibia will sag = false negative
ACL rupture could give you a false positive
Iso quad contraction during this test will move the tibia anteriorly = sucking sound and see tibia relocating
Can support patient in 90 degrees knee and hip flexion to use gravity to increase the sag
Variety sens and poor data on spec
What is the anatomy of the Lateral collateral ligament?
Shorter than the MCL
Cord like
Slants posteriorly from lateral epicondyle to the head of the fibula
Seperated from the lateral meniscus by the popliteus
Surrounded by tendon of the bicep femoris
Tightens in full extension
Stops varus, rotation in full extension
What are the signs and symptoms of a LCL injury?
Usually combined with more extensive damage
May get an arcuate fracture = avulsion fracture of the head of the fibula
What is the objective examination for a LCL injury?
Palpation of the head of the fibula to rule out an arcuate fracture
Varus stress test
No research
At what angles of the knee should you do the varus stress test?
0 degrees = to test the PCL
30 degrees = to test the LCL
Pain and laxity for both = LCL and PCL are injured
