Acute Injuries of the Knee Flashcards
What is the unhappy triad of the knee?
- commonly seen following a lateral blow to the knee and consists of damage to the:
- anterior cruciate ligament
- medial collateral ligament
- meniscus (classically the medial meniscus but recent evidence shows that the lateral meniscus is more commonly injured)
Who is most at risk of ACL tears?
- 15-45yrs
- Active individuals - 70% occur in sporting activities
- Females>Males
What are the functions of the ACL?
Prevents
- Posterior displacement of the femur
- Hyperextension of the knee joint.
- Minimises tibial rotation
- Resists valgus/varus stress
Where does the ACL arise from and attach to?
Arises from anterior intercondylar area of the tibia, and attaches to the posteromedial aspect of the intercondylar notch of the femur
How do ACL tears occur?
As a result of an acute non-contact deceleration injury, forceful hyperextension, or excessive rotational forces about the knee.
Tearing what ligament can also result in an ACL tear?
MCL
Is the ACL intracapsular or extracapsular?
Intracapsular
What are the symptoms of an ACL tear?
- Mechanism of injury - twisting motion
- Popping sound
- Swelling - rapidly (haemoarthrosis)
- Inability to return to play
What are the clinical signs of ACL tear?
- Instability
- Effusion
- Haemarthrosis? - immediate swelling?
- Anterior Draw sign - positive
- Lachman’s test - positive
- Decreased ROM - esp. flexion
How would you investigate a suspected ACL tear?
Clinical diagnosis!!
Imaging
- MRI Scan (INITIAL TEST) - For clinical confirmation
How would you manage someone with a ruptured ACL?
- RICE
- Analgesia
- Protected weight-bearing - with crutches +/- knee immobiliser
- Physiotherapy
- Surgical reconstruction - autograft - iin the young/increased knee instability
What groups of individuals are more likley to suffer collateral ligament ruptures?
- Adults
- 20-35 yrs
- Most common in American footbal, skiing, rugby
Where are the attachment points for the MCL?
- Medial epicondyle of the femur
- Medial condyle of the tibia
Which collateral ligament attaches to its respective meniscus?
Medial collateral ligament
What is the function of the MCL?
- Resist valgus
- Resist external rotation forces
What are the attachement points for the LCL?
- Lateral epicondyle of femur
- Lateral surface of the head of the fibula
Does the LCL attach to the lateral meniscus?
No
What tendon passes deep to the LCL?
Tendon of popliteus
What causes LCL injuries?
Very rare in isolation
What is the mechanism of injury in a MCL tear?
- Valgus stress - blows to lateral aspect of the knee while foot is fixed
- External rotation load placed on the knee
- Overuse - Breast stroke whip kick, gymnastics
What are the symptoms of a collateral tear?
- Sudden sharp pain - medial or lateral side
- Feeling a crack
- Mechanism of injury - varus/valgus stress
What are the signs of a collateral ligament tear?
- Effusion - haemarthrosis if immediate
- Tenderness - over affected ligament
- Bruising? - over one side of the knee
-
Positive medial/collateral assessment
- Laxity on valgus stress - MCL damage
- Laxity on varus stress - LCL damage
How would you investigate someone with a suspected collateral ligament tear?
- MRI scan - clinical confirmation
- X-ray - fracture/loose body, avulsion
- US - tendon rupture, meniscal tears
How would you manage someone with a collateral ligament tear?
- RICE
- Analgesia
- Protected weight-bearing - with crutches +/- knee immobiliser
- Physiotherapy
- Surgical Reconstruction - rarely needed in MCL; LCL often more severe and can involve cruciates, therefore more likely to need surgery
What can injury to the lateral collateral cause?
Injury of the common peroneal nerve
What are menisci made of?
- Fibrocartilage - Fibro and chondroblasts in matrix of type 1 collagen
- Collagen fibres arranged in radial and circumferential orientation
Function of the menisci
- Improve articular congruency and increase stability of the knee
- Controlling complex rolling and gliding action of the joint
- Distributing load during movement
What side are menisci tears more common on?
Medical - the medial meniscus is much less mobile than the lateral.
What is an important thing to remember about the vascular supply of the menisci?
Vascular supply to menisci diminishes as you move more towards the centre of the meniscus - important when considering how to manage tear in relation to where it is
What can cause meniscal tears?
- Twist to the flexed knee
- Older - daily activites due to degenerative changes and ageing
What are the signs of a meniscal tear?
- Locked knee - due to displaced segment becoming lodged between femoral and tibial condyles
- Tender joint line
- McMurray’s Test positive/apley’s grinding test
- Swelling - may or may not be any swelling
- Pain on internal/external rotation
Thessaly’s test?
How would you investigate a suspected meniscal tear?
- MRI Scan - location, morphology, length, depth, stability
- X-ray - avulsion
How would you manage someone with a meniscal tear?
- RICE
- NSAIDs/Paracetamol
- Conservative - small tears heal spontaneuously
- Surgery - early arthroscopic repair in most circumstances, especially sports related tears
What is the typical traumatic knee injury triad?
ACL + MCL + medial meniscus following valgus stress with rotation of the knee.
What is osgood schlatter’s disease?
Tibial tubersoity apophysitis
Repeated traciton causes inflammation and chronic avulsion of the secondary ossification centres of the tibial tuberosity, leading to inflammation, hence its known association with physical overuse
What sex does osgood schlatters affect more commonly?
Males
What age range does osgood schlatters commonly affect?
10-15 years old
What are features of osgood schlatters?
- Pain below knee - worse on strenuous activity and quad contraction
- Swollen, tender area below knee
What investigations might you do in a child with suspected osgood schlatters?
- X-ray
- MRI
What might you see on X-ray in someone with osgood schlatters?
Tibial tuberosity enlargement +/- fragmentation
What might you see on MRI in a child with osgood schlatters disease?
Tendonitis
How would you manage a child with osgood schlatters disease?
- Modificaiton of daily activities
- Ice packs
- Oral NSAIDs
- Physiotherapy
- Consider surgery - drilling of the tibial tubercle, partial resection of the tibial tubercle, excision of the separated ossicle, and combination of these procedures
What is patellofemoral pain syndrome?
Patellofemoral pain syndrome is defined as knee pain resulting from mechanical and biochemical changes to the patellofemoral joint.
What is patellofemoral pain syndrome associated with?
- Lower limb malaligment
- Muscle imbalance
- Patella tracking abnormalities
What are features of patellofemoral pain syndrome?
- Patella aching - after prolonged sitting/cimbing stairs
- Positive clark test - pain on compression with tensed quadriceps
- Decreased/increased patella mobility
- J test positive
How would you diagnose Patellofemoral pain syndrome?
Clinical diagnosis
How would you manage someone with patellofemoral pain syndrome?
- Relative rest
- NSAIDs
- Physio - quad and hip strengthening exercises
- Surgery - rarely needed
What normally causes PCL injuries?
Dashboard injuries
What is osteochondiritis dessicans?
Typically affects males aged 15-20.
Is a tear of the cartialge at the end of the bone - appears as a loose body in the joint.
Most likely cause is trauma, whether by single impact or repeated micro trauma.
Signs of osteo chondritis dessicans
- Tenderness localised to one femoral condyle
- Positive wilson’s test
What is oscgood schlatters?
Pain and swelling over the tibial tuberosity. Can be bilateral.
Exacerbated by exercise.
Reslves when physis joins.
