Knee Flashcards
What two joints make up the knee?
Tibiofemoral
Patellofemoral
What caps the top of the tibia?
Menisci
What is the role of menisci?
They act as shock absorbers and distribute the weight across a wider area.
Name the four important ligaments within the knee
Medial & Lateral Collateral ligaments
Anterior Cruciate Ligament
Posterior Cruciate Ligament
What is the job of the ACL?
Prevents abnormal internal rotation of tibia
What is the job of the PCL?
Prevents hyperextension and posterior movement of the tibia
What does the MCL resist
Valgus forces
What does the LCL resist
Varus forces and external rotation
If a patient has Genu Varum where in the knee is the OA likely to be?
Medial
If a patient has Genu vagus where in the knee is the OA likely to be?
Lateral
History in meniscal tears
Twisting force on a loaded knee.
Localised pain along joint line, effusion develops.
Knee locks unable to fully extend.
History in ACL tears
Higher rotation onto a planted foot.
Patient hears a pop.
Haemarthrosis develops quickly with deep pain within the knee.
Patients complains of knee giving away when turning.
Valgus stress injury (tackle fro the side)
MCL torn but also risk of ACL rupture.
PCL tear
Direct blow to anterior tibia with knee flexed
Varus stress
Can rupture lateral collateral ligament, +/- PCL
What is the issue surrounding examination of a knee post injury?
Very painful for the patient. Swelling and apprehension can make it difficult.
MRI used acutely if severe injury suspected.
Otherwise reassess in 2-7 days
What percentage of the force applied to the knee does the menisci take?
60%
In what portion of the menisci is there a blood supply?
Outer 1/3
Which menisci are more likely to be damaged?
Medial are 10x more likely to be damaged than the lateral.
Why is the medial menisci more likely to be ripped?
As it is fixed whilst the lateral menisci are more mobile.
What are the four types of meniscal tear?
Longitudinal
Radial
Oblique
Horizontal
What is a large longitudinal tear called?
Bucket Handle
What is the clinical sign of a bucket handle tear?
Locking knee which is unable to fully extend.
What imaging is used to confirm a diagnosis?
MRI
When is meniscal repair considered?
In younger patients with a tear in the outer 1/3. Meniscus is sutured to its bed.
25% of repairs fail
What is the other method of surgically treating meniscal tears
Athroscopy so removal of the menisci
How does treatment vary in degenerative meniscal tears?
The menisci should not be removed as this works to only make the OA worse.
What are the non surgical options in the treatment of meniscal tears?
Steroid injection
What is main complaint in an ACL rupture?
Rotary instability, giving away on turning
How quickly does swelling arise in any tendon rupture?
Within the hour.
Haemarthrosis due to the blood supply.
What are the two options for ACL rupture treatment
Repair - not very effective
Reconstruction
Which candidates are aimed straight for reconstruction?
Professional athletes and those wanting to continue high impact sports, as quickly as possible.
What occurs in ACL reconstruction?
Tendon graft is passed through tibial and femoral tunnels and secured to the bone.
What tendons are use as grafts in ACL reconstruction
Patellar
Semitendinosis
Gracilis
How long with physiotherapy involved is the recovery time?
Up to a year
In MCL tears what is the main complication post recovery?
Laxity and or pain on Valgus stress.
Tenderness over MCL insertion.
How are acute MCL tears usually treated?
Hinged knee brace as MCL healing is expected in majority of partial and even full tears.
In a chronic MCL instability what are the treatment options?
MCL tightening
Reconstruction with tendon graft.
What makes up the extensor mechanisms in the knee?
Patellar tendon
Patellar
Quadriceps tendon
Quadriceps Muscles
What age group do patellar tendon ruptures usually occur in?
<40
What age group do quadricep tendon ruptures usually occur in?
> 40
What are some predisposing condition for extensors mechanism ruptures?
Tendonitis Chronic steroid use or abuse Diabetes Rheumatoid arhtritis Chronic renal failure
What antibiotics increase the risk of tendon rupture?
Quinolones
Ciprofloxacin
Why should steroid injections never be used to treat tendonitis?
As steroids break down muscle fibre leading to tendon rupture.
What test should be used in a suspected extensor mechanism rupture.
Straight Leg Raise Test
How will a partial tear in the Extensor mechanism present?
They will have some extensor mechanism function but reduced power.
What is the treatment in extensor mechanism rupture?
Surgical tendon to tendon repair or reattachment.
Clinical signs of an extensor mechanism rupture?
-ve straight leg raise
Palpable gap
X-ray or US imaging
What is usual method of injury in an EMR?
Falling onto flexed knee with quadriceps contraction.
Method of injury in an patellar dislocation?
Direct blow or sudden twist of the knee.
In which direction does the patellar usually displace?
Laterally
What factors increase your risk of a patellar dislocation?
Ligament laxity.
Female
Valgus knees
High riding patellar
What is the risk of recurrent dislocations?
10%
What ligament is damaged or torn in a patellar dislocation?
Patellofemoral ligament
Treatment of a patellar dislocation
Manual manipulation to reset the patellar then a straight leg brace.
Recurrent then surgery to reconstruct patellofemoral ligament.
