The Lower Limb (2)- The knee, femoral triangle, anterior thigh and medial thigh

Question 1

femoral shaft fractures

• Signs and symptoms
• treatment

Answer 1

The patient will have a tense swollen thigh. Patient may develop hypovolaemic shock. The blood loss in open femoral fractures may be double this amount.

Femoral shaft fractures are treated with surgical fixation.

Question 2

mechanism of injury of distal femoral fracture

Answer 2

The usual mechanism is a high-energy sporting injury and there is often significant displacement of the fracture fragments.

In the elderly, this type of fracture is usually seen in association with osteoporotic
bone; the usual mechanism in the elderly is a fall from standing.

Question 3

how tibial plateau fracture occur

Answer 3

Tibial plateau fractures also tend to be high-energy injuries. The usual mechanism
is axial (‘top to bottom’) loading with varus or valgus angulation (an abnormal
medial or lateral flexion load) of the knee.

The articular cartilage is always damaged

most patients will develop a degree of post-traumatic
osteoarthritis in the affected joint.

Question 4

unhappy triad

Answer 4

The unhappy triad (or ‘blown knee’) is an
injury to the anterior cruciate ligament,
medial collateral ligament and medial
meniscus. This results from a strong
force applied to the lateral aspect of the
knee. The medial meniscus is firmly
adherent to the medial collateral
ligament, which is why it is also injured.

Question 5

patella fractures

Answer 5

They are either caused by a
direct impact injury (e.g. knee against
dashboard) or by eccentric contraction of the
quadriceps

Question 6

how to tell patella is fractured

Answer 6

On examination, there
is often a palpable defect in the patella and a
haemarthrosis (blood in the joint).
If the extensor mechanism is disrupted (i.e.
the fracture completely splits the patella
distal to the insertion of the quadriceps
tendon), the patient will be unable to
perform a straight leg raise i.e. to lift the leg
off the bed by flexing at the hip and keeping
the knee extended

Question 7

treatment of patella fractures

Answer 7

Displaced patellar fractures require reduction and surgical fixation.
Undisplaced patellar fractures can be protected whilst healing takes place
through splinting and using crutches, and do not usually require surgical
fixation.

Question 8

subluxation

Answer 8

partial displacement

Question 9

factors that predispose the patella to dislocate

Answer 9

 Generalised ligamentous laxity
 Weakness of the quadriceps muscles, especially the VMO
 Shallow trochlear (patellofemoral) groove with a flat lateral lip
 Long patellar ligament
 Previous dislocations

Question 10

treatment of patella dislocation

Answer 10

The treatment involves extending the knee then manually reducing the patella.
Immobilisation is used whilst healing takes place, and this is followed by physiotherapy
to strengthen the Vastus medialis obliquus

Question 11

most common type of knee injury

Answer 11

meniscal injuries

Question 12

how do meniscal injuries occur

Answer 12

typically occur during a sudden twisting motion of a weight-bearing knee in a high degree of flexion

Question 13

symptoms of meniscal injuries

Answer 13

• intermittent pain, localised to the joint line,
• knee clicking, catching, locking (inability to fully extend the knee due to an intra-articular foreign body)
• sensation of giving way.
• Swelling occurs as a delayed symptom due a reactive effusion or not at all, as the menisci are largely avascular (except at their periphery).

-Acute
haemarthrosis indicates a tear in the peripheral
vascular aspect of the meniscus or an associated injury to the anterior cruciate
ligament.

• A chronic effusion (increased synovial
  fluid) can occur due to synovitis (inflammation of the synovial membrane).

Question 14

treatment of meniscal injury

Answer 14

-surgically by either
meniscectomy or meniscal repair.

-conservative management is increasingly being recommended for these.

Question 15

why is conservative management becoming a more common treatment for meniscal injury

Answer 15

there is increasing evidence that
meniscal tears that result from a chronic degenerative process within the knee
have a similar prognosis with conservative management as with surgery. Hence,
conservative management is increasingly being recommended for these.

Question 16

what prevents excessive posterior motion of the tibia on the femur

Answer 16

Together, the collateral ligaments also work with the
posterior cruciate ligament (PCL) to prevent excessive
posterior motion of the tibia on the femur.

Question 17

varus

Answer 17

medial angulation of the distal segment

Question 18

valgus

Answer 18

lateral angulation of the distal segment

remember vaLgus Lateral

Question 19

acute valgus strain

Answer 19

The medial collateral ligament (MCL)
is at risk and in varus strain the lateral collateral ligament (LCL) is at risk. The MCL is
injured more commonly than the LCL, but a torn LCL has a higher change of causing
knee instability.

Question 20

which collateral ligament is at risk in valgus/varus strain and why

Answer 20

medial collateral ligament

lateral

Question 21

which collateral ligament is injured more commonly

Answer 21

The MCL is
injured more commonly than the LCL. This is because the medial tibial plateau forms a deeper and more
stable socket for the femoral condyle than the lateral tibial plateau

Question 22

symptoms of Collateral Ligament injury

Answer 22

Immediately after the injury, the patient will experience pain and swelling of the
knee. As the initial pain and stiffness subside, the knee joint may feel unstable and
the patient may complain of it giving way or not supporting their body weight.

Question 23

which cruciate is weaker and more commonly injured

Answer 23

the anterior

Question 24

what causes the anterior cruciate ligament to be injured

Answer 24

usually torn as a result of a quick
deceleration, hyperextension or rotational injury

It is usually a non-contact injury

The ACL can also be torn by application of a large force to the back of the knee with the joint partly flexed.

Question 25

symptoms of ACL injury

Answer 25

The patient typically reports feeling a popping sensation in their knee with
immediate swelling. When the swelling has subsided, the patient experiences
instability of the knee as the tibia slides anteriorly under the femur. Patients tend
to describe this as the knee ‘giving way’.

Question 26

anterolateral rotatory instability

Answer 26

ACL is torn, rotation of the tibia occurs with the PCL as the centrally-located axis;
the medial tibial condyle rotates internally and the lateral tibial condyle subluxes
anteriorly. Spontaneous reduction of the lateral tibial condyle then occurs with a
sudden ‘slip’ when the knee is flexed to 20-40˚. This is characterized by a sudden
sensation of the knee ‘giving way’

Question 27

treatment of ACL injury

Answer 27

surgical reconstruction if used often

Question 28

causes of PCL injury

Answer 28

‘dashboard injury’; the knee is flexed and a large force is applied to the upper tibia, displacing it posteriorly.

The PCL can also be torn during football when the player falls on a flexed knee with their ankle plantarflexed. The tibia hits the ground first and is displaced posteriorly, avulsing the PCL.

A tackle with the knee flexed can also cause this
injury.

Finally, a severe hyperextension injury can also avulse the PCL from its insertion on the posterior aspect of the intercondylar area.

Question 29

what has to be done for the knee to dislocate

Answer 29

To dislocate the knee joint, at least three of the four ligaments
(MCL, LCL, ACL and PCL) must be ruptured.

Question 30

what is often associated with a dislocation of the knee joint

Answer 30

popliteal artery is
tethered proximally when it enters the popliteal fossa at the adductor hiatus and
distally where it exits the popliteal fossa by passing under the tendinous arch of
the soleus muscle

Question 31

what can cause swellings around the knee

Answer 31

bony
soft tissue
fluid

Question 32

bony swellings of knee

Answer 32

Bony e.g. Osgood-Schlatter’s disease

Question 33

soft tissue swellings of the knee joint

Answer 33

o Localised e.g. an enlarged popliteal lymph node; a popliteal artery
aneurysm
o Generalised e.g. lymphoedema of the lower limb

Question 34

fluid swelling of the knee joint

Answer 34

o Inside the joint = effusion
o Outside the joint = soft tissue
haematoma

Question 35

what is an effusion

Answer 35

An effusion is an accumulation of fluid inside the knee joint; it is never normal.

Effusions can be acute (defined as < 6 hours after injury e.g. after cruciate
ligament rupture) or delayed (> 6 hours after injury)

Question 36

haemarthrosis

Answer 36

bleeding inside the joint

ACL rupture until proven otherwise

Question 37

what causes delayed swelling of the knee

Answer 37

usually due to reactive synovitis. Inflammation of the synovium in response to injury. Leads to production of an increased volume of synovial fluid

Question 38

lipo-hemarthrosis

Answer 38

(blood and fat in the joint). A lipo-haemarthrosis is a
fracture until proven otherwise as the fat has usually released from the
bone marrow.

Question 39

bursitis of the knee

Answer 39

Bursitis is inflammation of a bursa.
The bursae of the knee that are
most commonly inflamed are the
prepatellar bursa, infrapatellar
bursa, pes anserinus bursa and
the suprapatellar bursa

Question 40

pre-patellar bursa

Answer 40

The pre-patellar bursa is a superficial bursa with a thin synovial lining, located
between the skin and the patella.

Question 41

symptoms of of pre patellar bursa

Answer 41

The patient usually presents with knee pain and swelling. There may be some
erythema overlying the inflamed bursa. The patient finds it difficult to walk due to
the pain and will not be able to kneel on the affected side.

Question 42

infrapatellar bursitis

Answer 42

occurs due to repeated microtrauma caused by
activities involving kneeling. The popular name clergyman’s knee, reflects the
more upright position of kneeling that generally triggers this condition.

Question 43

infrapatellar bursa

Answer 43

occurs due to repeated microtrauma caused by
activities involving kneeling. The popular name clergyman’s knee, reflects the
more upright position of kneeling that generally triggers this condition.

Question 44

what does bursitis most commonly affect

Answer 44

superficial infrapatellar bursa

Question 45

causes of knee effusion

Answer 45

 Osteoarthritis
 Rheumatoid arthritis
 Infection (septic arthritis; see below)
 Gout and pseudogout
 Repetitive microtrauma to the joint (as a result of running on soft or
uneven surfaces).

Question 46

suprapatella bursa

Answer 46

extension of the synovial cavity of the knee joint

Question 47

semimembranosus bursitis

Answer 47

If the knee joint is inflamed
and there is an effusion, the fluid can force its way through this narrow
communication into the semimembranosus bursa. The resulting swelling in
the popliteal fossa is known as semimembranosus bursitis or more commonly
as a popliteal cyst or Baker’s cyst.

Question 48

Osgood-Schlatter’s disease

Answer 48

OSD is inflammation of the apophysis (site of insertion) of the patellar ligament
into the tibial tuberosity.
OSD most commonly occurs in teenagers who play sport (running and jumping)
and causes localised pain and swelling. It is bilateral in 20-30% of cases.

Question 49

crepitus

Answer 49

a grating sound and crackling sensation on movement of the joint

Question 50

septic arthritis of the knee

Answer 50

Septic arthritis is the invasion of the joint space by micro-organisms,
usually bacteria (but occasionally viruses, mycobacteria and fungi). It
differs from reactive arthritis, which is a sterile inflammatory process
that can result from an extra-articular infection e.g. gastroenteritis.

Question 51

what pathogens cause septic arthritis

Answer 51

The most common pathogen is Staphylococcus aureus. Other pathogens
include Staph. epidermidis, Neisseria gonorrhoeae (in sexually active
individuals), Strep. viridans, Strep. pneumoniae and the Group B Streptococci.

Question 52

symptom of septic arthritis

Answer 52

 Fever (40-60% of cases)
 Pain (75%)
 Reduced range of motion

Question 53

treatment of septic arthritis

Answer 53

Aspiration of the joint should be carried out
immediately and the aspirate should be sent for urgent microscopy, culture and
sensitivities.
Septic arthritis carries a high morbidity, even if treated optimally.

Question 54

which tibial plataeu fractures are most common

Answer 54

They can be unicondylar (affecting one condyle) or bicondylar (affecting
both tibial condyles). Fractures affecting the lateral tibial condyle are the most
common.