Knee Conditions Flashcards
Describe femoral hernias
Develop when an out-pouching of gastric viscera protrudes through the femoral canal
Protrusion becomes noticeable when it exits through the saphenous opening within the fascia lata = swelling inferior to the inguinal ligament
Describe the test for Trendelenburg’s Sign
Patient is asked to stand on one leg
If Tredenlenburg’s sign is positive, pelvis drops on unsupported side
Problem on stance leg, gluteus medius and minimus fail to lock the pelvis and cannot support the weight
Where are the safe areas for injections into the buttock
Need to avoid damaging sciatic nerve Dorsogluteal region (upper outer quadrant of the buttock) and Ventrogluteal region - to locate the ventrogluteal region, place the palm of one hand over the greater trochanter of the femur, point your thumb towards the inguinal region and your index finger toward the anterior superior iliac crest. Spread the index and middle fingers to make a V and inject between the PIPJ of your fingers into the gluteus medius muscle.
How does pathological locking of the knee come about
Unable to bend or extend the knee
True locking caused by a mechanical block where something gets stuck inside the joint, meniscus tear or loose body
Requires intervention - surgery
Valgus vs varus
Valgus - deviation of the distal limb away from the midline
Varus - deviation of the distal limb towards the midline
List common conditions of the knee
- Femoral shaft fractures
- Distal femoral fractures
- Proximal tibial fractures / tibial plateau fractires
- Patella fractures
- Patella dislocation
- Meniscal injuries
- Collateral ligament injury
- Cruciate ligament injury
- Pre-patellar bursitis
- Infrapatellar bursitis
- Compartment syndrome
Describe the cause and presentation of femoral shaft fractures
- Usually due to high velocity trauma - eg. Falls, road accidents
- Following the fracture, the proximal fragment is abducted due to pull of gluteus medius and minimus on the greater trochanter
- Leg also is flexed due to iliopsoas on the lesser trochanter
- Distal segment is adducted into a varus deformity due to the action of the adductor muscles and extended due to the pull of gastrocnemius on the posterior femur
Describe distal femoral fractures
- Usually due to high energy sporting injury causing significant displacement of the fracture fragment
- Popliteal artery may become involved - neurovascular examination
Describe proximal tibial fractures / tibial plateau fractures
- Fractures affecting the articulating surface of the tibia with the knee joint
- Fall onto an extended knee
- Often associated with meniscal tears and ACL injuries
- Can fracture one or both tibial condyles
- Knee swelling, pain on weight bearing, knee deformity
Describe patella fractures and presentation
- Due to direct impact injury or by indirect eccentric contraction
- Examination - palpable defect in the patella with swollen knee joint due to blood (haemarthrosis)
- Patient unable to perform a straight leg raise - lift leg off of bed by flexing at hip and extending at knee
Describe the types of patella fractures
- Stable fracture results in non-displacement
- Unstable fracture causes the broken ends of the bone to become separated and do not line up correctly
- Comminuted fracture shatters the bone into 3 or more pieces, can be stable or unstable
Describe presentation and cause of patella dislocation
- Most common direction is laterally
- Patella kept in position by contraction of the inferior fibres of vastus medialis
- Most common cause is trauma, often twisting injury or direct blow to the knee
- Eg. Changing direction quickly in sport
Describe cause and presentation of meniscal injuries
- Most common type of knee injury
- Occur as a result of a sudden twisting motion of the weight-bearing knee
- Present with intermittent pain, localised to the joint line
- Knee clicking, locking or sensation of giving way
Describe examination of meniscal injuries
- Examination shows joint line tenderness and restricted motion due to pain or swelling
- Mechanical block to motion or locking may occur
- Meniscal cyst may develop after tear during the healing response - causes discomfort to patient
- Acute haemathrosis may signify associated injuries of unhappy triad
Describe collateral ligament injury including presentation
- Common in sporting injuries from a direct blow to one side of the knee
- Medial and lateral collateral ligaments normally control the lateral movement of the knee joint and brace it against the unusual varus or valgus deformation
- Presents with immediate pain, swelling and stiffness
- MCL more commonly injured than LCL, but LCL tear has higher chance of causing knee instability
- MCL injuries commonly occur when the knee is slightly flexed