MSK 9 - Disorders of the Knee

Question 1

How are femoral shaft fractures caused?
In what sites can femoral shaft fractures occur?
What is associated with femoral shaft injuries?
How are they treated?

Answer 1

• High energy injuries, e.g.: road traffic accidents or falls from heights.
• Proximal (higher up), mid-shaft or supracondylar (just above femoral condyles).
• Significant blood loss - upto 1.5L which can cause hypovolaemic shock.
• Traction splint or surgical fixation.

Question 2

How are tibial plateau (top of the tibia) fractures caused?
What kinds can you get?
What are the potential consequences?
How is it treated?

Answer 2

• High energy injuries, e.g.: fall from height.
• Uni or Bi-condylar (1 or both condyles fractured)
• Instability, articular cartilage damage, post traumatic OA
• Articular segment need to be fixed back to shaft.

Question 3

How are patella fractures caused?
What kinds can you get?
What is a potential consequence?

Answer 3

• Direct or indirect force to patella
• Displaced or undisplaced
• Post-traumatic OA

Question 4

In which direction do patella dislocations occur?
How do they occur?
How are they treated?

Answer 4

• In a lateral direction
• Twisting actions in slight flexion, falling on a flexed knee
• Reduce & immobilise +/- soft tissue reconstruction.

Question 5

How is meniscal injuries occur?

What are the symptoms?

Answer 5

• Twisting injury in high flexion

- Localised pain, swelling and mechanical symptoms (knee is jamming or locking).

Question 6

How do medial and lateral collateral ligament injuries occur?
How are they treated?

Answer 6

• Via contact/direct blows e.g..: in sport
• Medial collateral = valgus strain (force towards midline)
• Lateral collateral = varus strain (force away from midline)
• Brace + rehabilitation, can cause “unhappy triad” (medial meniscal, ACL + MCL injury). May need surgical repair/reconstruction.

Question 7

How do ACL + PCL injuries occur?

Which type is more common?

Answer 7

ACL = non-contact, landing or direct change, “giving way”/”twisting and turning”. Most common.

PCL = contact - fall onto knee or hyperextension. Least common (1-2%).

Question 8

How do knee joint dislocations occur?

Out of the 4 ligaments, how many are ruptured?

Answer 8

• Very rare, caused by high energy trauma.
• 3 out of 4 ligaments ruptured
• Reduce + stabilise.

Question 9

What are the names given to inflammation of the bursae within the knee joint?

Answer 9

Pre-patellar bursitis = housemaids knee (from kneeling)
Infra-patellar bursitis = clergymans knee (kneeling but more erect position)
supra-patellar bursitis = knee-joint effusion
semimembranosus bursitis = popliteal (Baker’s) cyst

Question 10

What are the predispositions for knee OA?
When do symptoms occur?
How is it treated?
What are the 4 signs of OA seen during imaging?

Answer 10

• Age/sex/weight/post-trauma/genetics
• Symptoms fluctuate, provokes by activity, relieved by rest
• Strengthening exercises/analgesia/weight loss/activity modification/OA surgery.
• Due to cartilage thinning - joint space narrows, growth of osteophytes, sclerosis of knee joint + subchondral cysts.

Question 11

What are the signs of septic arthritis?
When can it occur?
How is it treated?

Answer 11

• Extreme pain, swelling, redness/warmth in knee joint
• After recent surgery, during knee effusion secondary to a bacterial infection.
• Antibiotics + surgical washout.