Knee Disorders Flashcards
What are the 3 standard views used for a knee X-Ray
Anterior-Posterior
Lateral
Skyline (Superiorly, with knee flexed)
What usually causes femoral shaft injuries in young adults and healthy children
In closed femoral shaft fractures, how much blood is lost and what may the patient develop
High velocity trauma
1000-1500ml, may develop hypovolaemic shock
In a femoral fracture, how does the proximal fragment appear and what muscles cause this
How does the distal fragment appear and what muscles cause this
Abducted- Gluteus medius and minimus
Flexed- Iliopsoas
Adducted- Adductor muscles
Extended- Gastrocnemius
What is the usual cause of a distal femoral fracture in young patients
Which artery may be involved
High energy- sporting injury, popliteal artery
- What is the usual cause of a Tibial Plateau Fracture
- What is affected in this kind of fracture
- Are they uni or bicondylar
- Which condyle is most commonly affected
- What 2 injuries are associated with these fractures
- Axial loading with varus/ valgus angulation of the knee
- Articulating surfaces of tibia within the knee joint
- Can be both
- Lateral tibial condyle
- Meniscal tears and ACL injuries
What 2 things can cause patellar fractures
What is the most common age range for these
What are 3 signs of a patellar fracture
Direct impact injury
Eccentric contraction of quadriceps
20-50 years
Palpable defect in patella
Haemarthrosis (Blood in joint)
Patient unable to perform a straight leg raise
Compare treatment of displaced and undisplaced patella fractures
Displaced: Reduction and surgical fixation
Undisplaced: Splints and crutches, surgery not usually needed
What can be mistaken for a patellar fracture
What causes this
A bipartite patella (8% of population)
Failed union of a secondary ossification centre within patella body
Compare patella dislocation and Subluxation
What’s the most common cause of patellar dislocation, and the mechanism
Dislocation: Patella completely displaced
Subluxation: Partially displaced
Trauma (Twisting injury/ direct impact)
Medial rotation of femur on a planted foot while knee is flexed
Identify 5 factors that can lead to patellar dislocation
Ligamentous laxity Weak quadriceps muscles Shallow trochlear groove Long patellar ligament Previous dislocations
Describe the treatment for patellar dislocation
Extend the knee, manually reduce the patella
Immobilise during healing, then physiotherapy to strengthen the VMO
How do meniscal injuries occur
Name 5 symptoms
Sudden twisting motion of a weight bearing knee in a high degree of Flexion
- intermittent pain
- knee clicking
- knee locking (can’t fully extend due to Intra-articular foreign body)
- delayed swelling may present
- knee ‘giving way’ (tibia slides anteriorly under femur)
Name 2 things that can be found on examination in a meniscal injury
- Joint line tenderness
- Reduced motion due to pain/ swelling
Why does an Injured Lateral Collateral Ligament have a higher chance of causing knee instability
What is the Unhappy Triad
Because medial tibial plateau forms a deeper, more stable socket than the lateral condyle
Injured ACL, MCL and Medial Meniscus caused by strong force to knee from lateral side.
Which Cruciate ligament is weaker and more commonly injured
List 4 causes of this being injured
ACL
- Quick deceleration
- Hyperextension
- Rotational injury
- Large impact to back of partially flexed knee
The ACL prevents medial rotation of an extended knee. Describe effects of a torn ACL on lateral and medial tibial condyles
What does this lead to and what is this called
- Medial tibial condyle rotates internally
- Lateral tibial condyle subluxes anteriorly
Reduction of lateral tibial condyle occurs with a sudden ‘slip’ when knee is flexed.
Anterolateral rotatory instability
What is the most common mechanism of PCL injury
Name 2 tests used to detect an ACL Injury
Name 1 test used to detect a PCL injury
A ‘dashboard injury’- Large force applied to proximal tibia when knee is flexed
ACL: Lachman’s Test, Anterior Drawer Test
PCL: Posterior Drawer Test
How many of the 4 main ligaments must be injured for a knee dislocation to occur
Which artery is most at risk and why
Name 3 ways it can be injured
At least 3
Popliteal as it is very immobile
- May tear
- Crushed
- Traction injury (endothelial damage-> Thrombosis)
What are 3 types of knee swelling
Bony
Soft tissue (Localised OR Generalised)
Fluid
What is a knee effusion
What are the 2 types
Accumulation of fluid inside knee joint
Acute/ delayed (> hours after injury)
What are 2 types of acute knee effusion
What is the initial suspected cause for each
Haemarthrosis: Blood in joint- ACL rupture
Lipo-haemarthrosis: Blood and fat in joint- Fracture
Which 5 knee Bursae are most commonly inflamed
Prepatellar bursa
Infrapatellar bursa (Deep and subcutaneous)
Subsartorial bursa (Pes Anserinus bursa)
Suprapatellar bursa
Identity 4 signs of Pre-patellar bursitis
Identify 3 causes, and suggest an alternate name for this type of bursitis
Knee pain + swelling
May be erythema
Difficulty walking
Unable to kneel
Repetitive trauma (E.g floor scrubbing)
Falling onto knee
Blunt trauma to knee
“Housemaid’s knee”
In Infrapatellar bursitis, which is bursa is most commonly affected
What is the usual cause of Infrapatellar bursitis and what is another name for Infrapatellar bursitis
Most common- Superficial Infrapatellar Bursa
Repeated micro trauma caused by activities involving kneeling
Clergyman’s Knee
