Soft Tissue Knee Injuries Flashcards
What is the purpose of the menisci?
to distribute load from convex femoral condyles to relatively flat tibial articular surfaces
What are the differences between the lateral and medial menisci?
medial is fixed whislt the lateral meniscus is more mobile; medial is under a greater amount of shear pressure
Why does the knee pivot on the medial meniscus through flexion and extension?
due to shpae and soft tissues the tibia interally rotates on flexion and externally rotates on extension
What type of stress does the MCL resist?
valgus stress
what type of stress does the LCL resist?
varus stress
What does the ACL resist?
anterior subluxation of the tibia and internal rotation of the tibia in extension
What does the PCL resist?
posterior subluxation of the tibia and hyperextension of the knee
Why does the MCL heal well?
has a very good blood supply
What type of instability does an MACL rupture lead to?
valgus instability
What type of instability does an ACL rupture lead to?
rotatory instability
What type of instability does a PCL rupture lead to?
recurrent hyperextension or instability descending stairs
What causes a meniscal tear in younger patients?
a sporting injury or getting up from squatting positions
What can cause a medinscal tear in older patients?
atraumatic spontaneous degenrate tears
How are meniscal tears investigated?
MRI
Which meniscus is more likely to be torn?
medial 10x as common
Why is there limited healing potential with meniscal tears?
only the peripheral third has a blood supply
When should a menisectomy be considered?
mechanical symptoms- painful catching or locking or irreparable tear os failed meniscal repair
How should the menisci appear on MRI?
like a black boe-tie; any white in the bows indicates a tear
What does an acute locked knee signify?
a significant displaed bucket handle meniscal tear
What would happen if the knee remains locked for an extended period of time
Patient may develop fixed flexion defomrity
What is the link between a degenerative meniscal tear and OA?
probably represents the first stage of OA
What are hte grades in a knee ligament injury?
grade 1- sprain-tear some fibres but macroscopic structure intact; grade 2- partial tear; grade 3- complete tear
What are the treatments for an MCL injury?
brace; early motion; physi
How are ACL treated?
repair doesnt work- reconstruction only- autograft using patellar tendon or hamstrings;PT
What is the rule of thirds in ACL rupture
a third can compensate and are able to funcion well; a third can avoid instability by avoiding certain activites and a third do not compensate and have frequent instability
What is the role of ACL reconstruction?
to fix rotary instaibilty not responding to physio- does not treat pain or prevent arthritis
How is the LCL injured?
by varus and hyperextension
What nerve is commonly damaged in an LCL tinjury?
the common fibular nerve
What is the problem with an LCL injury?
it doesnt heal
What causes a PCL rupture?
a direct blow to anterior tibia or hyperextension injury
What are the symptoms of PCL ruptre?
popliteal knee pain and bruising
What type of instability results with PCL rupture?
recurrent hyperextension or feeling unstable when going downstairs
What are the common complications associated with knee disloactions?
popliteal artery injury (tear; intima tear and thrombosis); nerve injury- common fibular nerve; compartment syndrom
What is the managment fro a knee dislaction?
emergency reduction and recheck of neurovascular status; multi-ligament reconstruction
What causes a patellar dislocation?
rapid turn or direct blow
Who gets patellar dislocation?
females; adolescents; ligamentous laxity; valgus knee
How many patients with patellar disolcation get recurrent dislocation?
10%
What type of trauma causes an extensor mechanism rupture?
a fall onto flexed knee with quads contraction
What predisposes to an extensor mechanism rupture?
previous tendonitis; steroids; chronic renal failure; ciprofloxacin
What is seen on exam with an extensor mechanism rupture?
unable to straight leg raise; palpable gap
What is the treatment for an extensor mechanism rupture?
surgical repair
Haemarthrosis is seen with what injuries?
ACL rupture or fracture
What causes pain on the joint line?
meniscal/chondral pain
What is the most likely cause of this presentation? twist, pop, haemarthosis; generalised pain; pain settles after a few days; rotary instability
ACL rupture
what is the most likely cause of this presentation?- getting up from squatting, sudden sharp pain medial joint line, effusion, recurrent medial pain and catching +/- locking
meniscal tear
