Knee Soft Tissue Injuries Flashcards
What is the main function of the medial cruciate ligament?
Resists valgus stress
What is the main function of the lateral cruciate ligament?
Resists varus stress
What is the main function of the ACL?
resists the tibia slipping anteriorly on the femur and internal rotation
What is the main function of the PCL?
resists the tibia slipping posteriorly on the femur
What is a grade 1 ligament injury?
Sprain - some fibres are torn but macroscopic structures are intact
What is a grade 2 ligament injury?
Partial tear
What is a grade 3 ligament injury?
complete tear
Which structures make up the extensor mechanism?
Quadriceps muscles Quadriceps tendon Patella Patellar tendon Tibial tuberosity
What are some risk factors for an injury to the extensor mechanism of the knee?
Previous tendonitis Steroids RA Chronic renal failure Diabetes Ciprofloxacin & other quinolone antibiotics - cause tendonitis
Describe the mechanism of injury in a extensor mechanism injury?
fall onto flexed knee with quads contraction, flexed knee and lifting heavy weight - basically anything that puts strain on the extensor mechanism
what is a palpable gap around the front of the knee and unable to resist pressure when lifting an extended leg signs of?
Extensor mechanism injury
What will confirm diagnosis of extensor mechanism injury?
ultrasound scan
management of extensor mechanism injury?
surgical repair
which of the two menisci is more likely to get injured?
Medial menisci
What is locking of the knee and pain localised to the joint line signs of?
Meniscal tear
Why can you get locking of the knee in meniscal tears?
ripped bit of the menisci flips on itself and prevents the knee from extending fully - usually in bucket handle tears
What type of imaging is most appropriate for a menisci tear?
MRI
Explain the mechanism of injury in menisci tears?
twisting on a loaded knee e.g. squatting, football
Why do mensci tears have limited healing potential?
only the outer third has vascular supply so no point operating unless this part is affected
what would impact to the lateral side of the knee e.g. a rugby tackle potentially cause?
MCL injury +/- ACL injury
Management of MCL injuries?
Brace with early mobilisation
Physio
Pain can take months to settle
What nerve is at risk in a LCL injury?
Common fibular nerve
explain the mechanism of injury in an ACL rupture?
high rotational force - body moves laterally on a planted foot
high impact sports like football, rugby, skiing
signs/symptoms of ACL rupture?
PAIN
“pop” heard/felt on injury
haemarthrosis formation within hour of injury (effusion due to blood in the joint)
Why does haemarthrosis occur in ACL ruptures?
ACL has its own arterial blood supply which is disrupted
Management of ACL rupture?
surgical reconstruction - tendon graft
physio after surgery
Explain the mechanism of injury in a PCL rupture?
direct blow to anterior tibia/hyperextension injury e.g. motorbike accident
Symptoms of PCL rupture?
Popliteal pain & bruising
Instability - hyperextension and going down stairs
Management of PCL rupture?
Dont operate if rupture in isolation
Surgical reconstruction if multiple ligament injury
Which way is the patella most likely to dislocate?
Laterally
