Knee Flashcards
What usually causes meniscal tears?
Sporting injury eg twisting
Secondary to ACL tears (in 50% of cases)
Elderly degenerative tears (20% of over 50s), which can show early stages of OA
What is the most common meniscal tear?
Medial
What are the types of meniscal tear
Horizontal
Longitudinal
Parrot beak
Radial
Bucket handle
How do meniscal tears present?
Localised pain and tenderness, ‘knee about to give way’
Locking (bucket handle)
Inflammatory effusion
Why are bucket handle tears more severe?
Fragment displacement into intercondylar notch can obstruct normal knee mechanism- causes acute locking
How are meniscal tears investigated?
Mcmurray test positive
MRI- first line
Arthroscopy- gold standard can also be used to treat
How are meniscal tears treated?
RICE
NSAIDs for analgesia
Physio
Surgery/arthroscopy if required in more severe cases
What are the Ottawa rules for who needs an X-ray of the knee?
Age 55 or above
Patella tenderness (with no tenderness elsewhere)
Fibular head tenderness
Cannot flex the knee to 90 degrees
Cannot weight bear (cannot take 4 steps – limping steps still count)
What causes ligament tears
Often forceful rotational movement
Also high impact injury or sudden stops
What are the ligament tear grades?
1- sprain, microtears
2- partial tear
3- complete tear
What does each ligament do?
MCL resists valgus stress
rupture -> valgus instability
LCL and ACL resists varus stress
Rupture -> varus instability
PCL resists posterior subluxation of femur
Rupture -> hyperextension and general instability
Presentation of the different ligaments tears
MCL and LCL-
Swelling and ecchymosis, localised pain, bruising, tenderness over associated joint line
MCL valgus instability and LCL varus instability
PCL- popliteal pain and bruising
ACL- pop on injury and haemarthrosis
Diffuse pain, which settles but will leave rotational instability
What is a complication of LCL?
May cause foot drop due to possible peroneal nerve injury
How are ligament tears investigated?
Informed by symptoms
X-ray
MRI- gold standard
Drawer tests for cruciates and stress tests for collaterals
Management for knee ligament tears
ACL- surgery via tendon grafting often required
PCL- conservative management, surgery only needed if more severe or other structures involved
MCL- heals well with conservative management due to rich blood supply
LCL- poor blood supply so usually needs surgery, as well as extra complication risk
What causes patella dislocation
Direct impact
Sudden quad contraction
Most common in teenagers, particularly female
In what direction would a patella dislocate?
Always lateral, never medial
What are some risk factors for patellar dislocation
Hypermobility
High Q angle- more genu valgum
Underdeveloped lateral femoral condyle
High riding patella
Weak quad insertions
How do patellar dislocations present?
Medial pain, effusion
Positive patellar apprehension test
History of dislocation increases likelihood
How are patellar dislocations investigated and managed?
X-ray
Resolution may be spontaneous or may need manipulation
Aftercare involves physio and painkillers
In rare cases a brace and aspiration is needed
Surgically stabilise if it keeps happening
How does a complete knee dislocation differ from a patella dislocation?
Patellar involves just patella
Complete knee involves misalignment between tibia and femur
What causes a complete knee dislocation?
Severe high impact injury
How does a complete knee dislocation present?
Severe pain and instability, knee grossly deformed
How is a complete knee dislocation investigated?
X-ray to confirm dislocation
CT angiogram if concerned about neurovascular status
MRI for ligament and soft tissue involvement
Management for complete knee dislocation
Neurovascular status is key, as prolonged ischaemia has very bad consequences
Requires immediate surgical reduction
What causes patellar fracture?
Traumatic injury or rapid quad contraction with flexed knee
How does a patellar fracture present?
Severe localised pain with palpable defect
Can’t lift leg or perform straight leg raise
Haemarthrosis
How is a patellar fracture managed?
Conservative- knee immobilised in extension
Operative- severity dependent, ORIF all the way to patellectomy
What is a tibial plateaux fracture and what causes them?
Fracture to the proximal part of the tibia, caused by high energy injuries (or low in elderly)
What assessment criteria is used to classify tibial plateau fractures?
Schatzer classification :
I- lateral split
II- lateral split with depression
III- depression
IV- medial split
V- bicondylar
VI- metaphysis diaphysis dissociation
Tibial plateaux fracture presentation and investigation
Presents with severe pain, instability, weight bearing difficulty
X-ray:
Horizontal lateral beam may show lipohaemarthrosis, bone fragments
CT:
To judge condylar involvement to guide treatment
Management for tibial plateaux fracture
Conservative- casting
Operative- ORIF or TKR depending on severity
What are some complications of a tibial plateaux fracture?
Lateral blow many damage common fibular nerve
Risk of associated soft tissue injury and compartment syndrome
What does the knee extensor mechanism consist of?
Tibial tuberosity
Patellar tendon
Patella
Quadriceps tendon
Quadriceps muscle
What causes an extensor mechanism rupture?
Middle aged running and jumping sports
Blunt trauma
Failing on flexed knee
Rapid contractile force can trigger a rupture, especially with natural degeneration
In younger patients patellar tendon most common but this becomes quadriceps with old age
What are the risk factors for an extensor mechanism rupture
History of tendonitis
Steroids
Renal failure
Ciprofloxacin (and other quinolones)
RA
Diabetes
How does an extensor mechanism rupture present?
Knee pain and weakness
Unable to straight leg raise
Palpable gap
How is an extensor mechanism rupture diagnosed
Clinical- if they can do a straight leg raise you can rule it out
X-ray- effusion, displaced patella
USS MRI- tears, also better for larger patients
Management for an extensor mechanism rupture
Usually urgent surgical repair -> physio
However small tears can be treated by immobilisation
What are loose bodies in the knee
Small bone or cartilage fragments that can move freely in knee synovium
What causes a loose body?
Trauma
Joint degeneration
Osteochondritis dissecans
How do loose bodies present?
Random sharp pain- never constant
Suggestive signs ie a lump, locking
What causes locking in a loose body
Can get nutrition from synovium so may grow and stick to synovium, causing locking
Investigation of a loose body
X-ray for calcifications, MRI for cartilaginous fragments
Often overdiagnosed -> the fabella is an accessory ossicle found in 40% of people which may be confused as one
How can loose bodies be treated?
Can be surgically removed but outcome is dependent on cause-
If cause is degenerative disease like arthritis then removal won’t help degenerative related pain
What can cause bone bruising, and what is the management plan?
Microscopic fracture of trabecular bone with bleeding and inflammation
Caused by direct trauma or secondary to tears
Often presents with major pain after meniscal or ligament tears
Investigated by MRI and settles on its own after a few months
What is a patellofemormal disorder?
A disorder in patellofemoral articulation that results in anterior knee pain
How does a patellofemoral disorder present, and how is it managed and diagnosed?
Anterior knee pain made worse by walking downhill
Grinding and clicking, inactivity related stiffness
Locking- either literal locking or pain related restriction
Diagnosed clinically and managed with physio and taping
What is a bakers cyst and what does it often rise in conjunction with
Ganglion cyst found in popliteal fossa
Rises in conjunction with OA
How does a bakers cyst present and how are they managed?
Fullness and softness of bursa
Managed via controlling underlying OA (or any other causative condition)
What is bursitis?
Inflammation of the synovium lined sacs that protect bony prominences and joints
Caused by repeated pressure or trauma
How can bursitis present?
Pre patellar- kneecap
Olecranon- elbow tip
Trochanteric
How is bursitis managed?
Goes away itself, just stay off knees and take analgesia
What is the presentation of bursitis similar to?
Septic arthritis so must rule this out via aspiration
