Lower limb problems II Flashcards
Femoral shaft fracture is often due to
High energy injuries
Investigations for femoral shaft fractures
Xray
What can happen in displaced femoral shaft fracture
Substantial blood loss
Fat entering venous system causing embolism
-> resp distress / hypoxia / confusion
Management of femoral shaft fractures
- Thomas splint for temporary stabilisation
- closed reduction + IM nail / plate fixation
Subtrochanteric (proximal femur) fracture often occurs in
Osteoporotic bone in elderly
What are the issues with subtrochanteric fractures
It takes a long time to heal and Non-union often occurs due to poor blood supply to the area
Management of subtrochanteric fracture
- Thomas splint for initial stabilisation
- IM nail
What type of joint is the knee joint
Hinge type of synovial joint
Movements of the knee joint
Flexion
Extension
Small degree of internal and external rotation
Articulating surfaces of the knee joint
2 between femur and tibia
1 between femur and patella
What type of bone is patella
Sesamoid bone - bone embedded in tendon / muscle
The patella is embedded in which tendon
Quadriceps tendon
The joint capsule of the knee is supported by ligaments. What are the ligaments of the knee
Patellar ligament
Lateral collateral ligament
Medial collateral ligament
Anterior cruciate ligament
Posterior cruciate ligament
Which ligaments of the knee joints are intracapsular
Anterior and posterior cruciate ligaments
Name A-D
A- Lateral collateral ligament
B- Anterior cruciate ligament
C- Posterior cruciate ligament
D- Medial collateral ligament
Name A-H
A- iliotibial band
B- Anterior cruciate ligament
C- Menisci
D- Fibula
E- Quadricep muscles
F- Patella
G- Patellar ligament
H- Tibia
Apart from ligaments, what else helps support the knee
Iliotibial band
Attachment of anterior cruciate ligament
From the intercondylar region of tibia, blends with medial epicondyle of tibia
Ascends posteriorly and attaches to the lateral femoral epicondyle
Attachment of posterior cruciate ligament
From the posterior intercondylar region of the tibia
Ascends anteriorly and attach to the medial femoral condyle
Function of MCL
resists valgus stress (force from lateral side)
Function of LCL
Resist varus stress (force from medial side)
Resist posterior-lateral rotation of the knee
Function of ACL
Resists internal rotation of the tibia in extension (bones of the knee joint twist in opposite directions)
Prevent anterior subluxation of tibia (so tibia won’t move forward)
Function of PCL
Resists posterior subluxation of the tibia
Prevents hyperextension of the knee
Function of menisci
Shock absorbers
Distribute the load of weight evenly across the knee joint
What is special about medial menisci
It is attached to medial collateral ligament which makes it more likely to be damaged (damage to MCL often causes damage to medial meniscus)
Name A-D
A- Suprapatellar bursa
B- Prepatellar bursa
C- Infrapatellar bursa
D- Semimembranous bursa
Clinical significance of suprapatellar bursa
Abnormal fluid within the knee joint can fill in here causing visible swelling
The extensor mechanism of the knee describes
Quadricep muscles and tendon
Patella
Patellar ligament
The extensor mechanism of the knee is responsible for
leg extension at the knee
Distal femur fracture often occurs in
Osteoporotic bone
Injury mechanism of distal femur fracture
Fall onto flexed knee in osteoporotic bone
The knee of the patient with distal femur fracture is often
Flexed (cannot extend it)
Investigation of distal femur fracture
Xray - AP and lateral
Management of distal femur fracture
Fixed with plate and screws
Why is true knee dislocation a medical emergency
Due to its high chance of neurovascular injuries and compartment syndrome
True knee dislocation management
Multi‐ligament reconstruction (because in order for the knee to dislocate, all the ligaments must be broken)
Most common presentation of patellar dislocation
Lateral dislocation
Patellar dislocation is most common in
Teenagers ,female
Risk factors for patellar dislocation
Ligamentous laxity
Valgus alignment of the knee
Shallow trochlear groove
Symptoms of patellar dislocation
Pain and tenderness medially where the patellar ligament is torn
Clinical signs of patellar dislocation
Haemarthrosis (swelling)
Positive patellar apprehension test
What is haemarthrosis
Bleeding into synovial membrane
Describe the patellar apprehension test
- patient in supine / sitting up with knee flexed 30 degrees
- try to displace the patella laterally
Pain = positive
Investigations for patellar dislocations
Patellar apprehension test
Xray
What may be seen on xray for patellar dislocation
Lipohaemarthrosis
Associated osteochondral fracture
Management for patellar dislocation
Most spontaneously reduce when the knee is straightened
Splint
Physiotherapy
How likely are patients going to experience another patellar dislocation after one
10% experience another recurrent dislocation
How to prevent further recurrent dislocations of the patella
Physio to strengthen quadriceps
Risk decreases with as they grow older
Surgery
What can cause tibial plateau fractures to occur
High energy injury in young
Low energy injury in old osteoporotic bone
Tibial plateau fracture is classified by
Schatzker system
Tibial plateau fracture is an intra/extra-articular fracture
Intra-articular
Different presentations of tibial plateau fractures
split in the bone
a depression of the articular surface
a combination of both
Injury mechanism of tibial plateau fracture
valgus force to the knee with foot planted
Investigations for tibial plateau fracture
Xray - AP and lateral
CT
What may be seen on xray for tibial plateau fracture
lipohaemarthrosis; fat floating on top of blood which bled into the joint
Lipohaemarthrosis is a specific sign for
Intra-articular fractures
Complications of tibial plateau fracture
Blow to lateral aspect of knee -> damage the common fibular nerve
High risk of compartment syndrome
Damage to soft tissue
Sign of common fibular nerve damage
Foot drop
Why does common fibular nerve damage cause foot drop
Because the deep branch of common fibular nerve provides motor innervation to muscles in the anterior compartment of leg
Those muscles are required to dorsiflex the foot
Management of tibial plateau fracture
ORIF
Bone grafting for depressed fractures
TKR (most still require TKR despite other management)
Tibial plateau fracture is associated with soft tissue injury. How can this be a problem in management
Substantial soft tissue swelling -> requires temporary external fixation -> ORIF
Injury mechanisms of tibial shaft fractures
Torsional injury
Bending
Compressive force from deceleration
Direct force
Torsional injury can cause which fracture configuration of the tibial shaft
Spiral fracture
Compressive force from deceleration can cause which fracture configuration of the tibial shaft
Oblique fracture
High energy direct force can cause which fracture configuration of the tibial shaft
Comminuted fracture
Tibial shaft fracture is at a high risk of
compartment syndrome of the anterior compartment of leg
Investigation for tibial shaft fracture
Xray - AP and lateral
Management for tibial shaft fracture
above knee cast
ORIF with IM nails
What is valgus knee
When the bone at the knee joint is angled out and away from the body’s midline
Describe the image
Valgus knee
What is varus knee
When the bone of the knee joint is angled inwards towards the body’s midline
Describe the image
Varus knee
What factors increases the risk for knee osteoarthritis
Valgus / varus knee
Ligament injuries - esp ACL
Previous meniscal tears
Active occupation and hobbies
Which type of OA can valgus knee cause
Lateral OA
Which type of OA can varus knee cause
Medial OA
Injury mechanism of meniscal tears
Twisting force on loaded knee (weightbearingon knee) e.g. turning at football / squatting
How do most older patients get meniscal tear
Atraumatic, spontaneous tears due to weakened meniscus
Degenerative meniscal tear is an early sign of
knee oA
Rupture of which ligament is often associated with meniscal tear
ACL
Which type of meniscal tear is more common
Medial meniscal tear
Symptoms of meniscal tear
Pain and tenderness localised to medial/lateral joint line (depending on which type of tear)
Unable to fully straighten knee (true locking)
Knee about to collapse during walking
Why would patients with meniscal tears describe the feeling that their knee is going to collapse during walking
Because the meniscal fragment may be caught in the knee joint during movement
Patients with knee arthritis sometimes describe that their knee is stuck as well. Is this the same as locked knee in meniscal tears
No, meniscal tears cause true locked knee whereas arthritis causes pseudo-locking which can resolve spontaneously
Pseudo-locking vs true locked knee
Pseudo-locking can be resolved spontaneously whereas true locking cannot
True locking is due to a fragment trapped in knee joint whereas pseudo-locking is due to too much pain
Acute locked knee in a patient with meniscal tear suggests
Large bucket handle meniscal tear
Does true-locking occur in all patients with meniscal tear
No, only if the meniscal tear is severe and unstable enough to be flipped and trapped in knee
Clinical signs of meniscal tear
Swelling
Positive McMurray’s test (but may not be accurate)
Positive Steinman test (but may not be accurate)
Describe McMurray’s test for meniscal tear
- Patient supine
- Manually flex the hip and knee by grasping the patient’s feet
- Extend the knee with internal rotation of the tibia + varus (inwards) stress
- Then return to flexion of the knee and extend the knee again but with external rotation + valgus stress
Describe specifically what each step of Mcmurray’s test is testing for
- Flex -> extend knee with internal rotation + varus stress = tests for lateral meniscal tear
- Flex -> extend knee with external rotation + valgus stress = tests for medial meniscal tear
Describe Steinman’s test
- Patient supine
- Stabilise the knee in flexed position
- Hold the ankle of the leg
- Rotate the leg medially and laterally
Pain = positive
Pain during external rotation in Steinman test suggests
Medial meniscal tear
investigations for meniscal tear
Steinman’s
McMurray’s
MRI
How to differentiate between degenerative and acute meniscal tear
Degenerative tear is Steinman’s negative and likely to be associated with signs of OA
Why is it important to differentiate between degenerative and acute meniscal tear
Because management is different - degenerative tears are unlikely to benefit from arthroscopic meniscectomy whereas acute tears can
Management for acute meniscal tear
Meniscal repair (only indicated in some)
Arthroscopic meniscectomy (If meniscal repair fails / meniscal repair not indicated and pain does not settle after 3 months)
When is meniscal repair indicated
In young patients with fresh meniscal tears
Describe the healing of meniscal tears
Slow due to blood supply only on its outer 1/3
Healing potential decreases with increasing age
What are bucket handle tears
Large longitudinal meniscal tear, where the fragment can flip out and cause knee locks
Why may it be useful to see patients with suspected soft tissue injuries of the knee a few days later if not significant
Due to pain and instability limiting examination findings
What imaging technique is used to identify soft tissue injuries of the knee
MRI
If you suspect large soft tissue injury of the knee, what should you do
early MRI instead of seeing the patient again few days later
Which knee ligament is the most commonly injured
ACL
Mechanism of injury of ACL
Sudden pivoting with foot planted
Symptoms of ACL tear
Audible pop followed by pain and swelling
Pain settles but leaves rotatory instability
What is the main complaint that patients with ACL injury will present
Rotatory instability (ACL is responsible to resist the internal rotation of tibia)
Clinical signs of ACL injury
Excessive anterior movement of the tibia on anterior drawer test and Lachman test (ACL is responsible to prevent anterior subluxation of tibia)
Describe Anterior drawer test
- Patient supine, knee flexed
- Sit on the patient’s foot to immobilise the foot
- Grab the tibial head with both hands and pull it anteriorly
Positive = abnormal anterior movement of tibia
Describe the Lachman test
- Patient supine, knee slightly flexed
- tibia is slightly externally rotated
- Hold the knee with one hand and the tibial head with another hand
- Pull the tibial head anteriorly (like in anterior drawer test)
Positive = anterior movement of tibia
Investigations for ACL injury
Joint aspiration - may show haemarthrosis
MRI
Management of ACL injury
Some may compensate well (not heal)
Physiotherapy
ACL reconstruction if indicated
Rehab after ACL reconstruction
Why can’t ACL repair itself
Because there is no blood supply
When is ACL reconstruction indicated
No improvement from physio
Multiligament reconstruction
For professional athletes
Mechanism of injury of PCL injury
Direct blow to anterior tibia
Symptoms of PCL injury
Popliteal knee pain and bruising
Positive posterior drawer test
Positive sag test
Describe the sag test (Godfrey sign)
- Patient supine, knee flexed to 90 degrees
- Inspect the tibial tuberosities
Positive = tibia sags posterior compared to other knee
Investigations for PCL injury
Xray - PCL injury is often associated w other injuries
MRI
Sag test
Posterior drawer test
Management for PCL injury
Most don’t require reconstruction surgery
Reconstruction surgery for those that develop instability
What instability can PCL injury cause
Recurrent hyperextension
Feeling unstable when going down stairs
Mechanism of injury of MCL
Valgus stress - rugby tackling from the side
Symptoms of MCL
Knee swelling
Valgus instability
Medial joint line tenderness
Pain on valgus
Investigations for MCL injury
Clinical - valgus stress test
Xray / MRI if needed
Describe the valgus stress test
- Patient supine with knee in extension and slight external rotation
- Hold the ankle with one hand and the other hand hold the lateral condyle of the femur
- Push against the knee medially and laterally against the ankle
Positive = abnormal movement / pain
Management of MCL injury
Usually heals well
Hinged knee brace
MCL tightening / reconstruction for chronic MCL instability
Why does MCL injury heal well whereas ACL injury doesn’t
Because there is blood supply to MCL whereas there isn’t to ACL
LCL injury often occurs with
PCL or ACL injury
Uncommon on its own
Mechanism of injury of LCL
Varus stress
Hyperextension
Symptoms of LCL injury
Knee swelling
Varus instability
Lateral joint line tenderness
Positive varus stress test
Describe the varus stress test
- Patient supine, knee fully extended
- Hold the ankle with one hand and the medial epicondyle of knee with another
- Push against the knee laterally and medially against the ankle
Positive = abnormal movement / pain
Investigations for LCL injury
Clinical - Varus stress test
Xray / MRI if needed
Management of LCL injury
Early urgent repair
Late reconstruction for those that are later diagnosed
LCL injury is often associated with
Common fibular nerve damage
Multiligament injuries
Vascular injury - popliteal artery
