Knee Flashcards
What causes fractures of the femoral shaft?
High velocity trauma (young and healthy)
Low velocity injuries (elderly with osteoporotic bones)
What may a femoral shaft fracture look like?
Proximal fragment (abducted and flexed) Distal fragment (varus and extended)
Tense swollen thigh Hypovolaemic shock (due to blood loss)
How are distal femoral fractures caused?
Sporting injury with displacement (young)
Osteoporotic bones with fall from standing (elderly)
Why is reduction essential in a distal femoral fracture?
The popliteal artery may become involved
What causes tibial plateaued fractures?
High energy
Tibial loading with excess rotation of the knee
What are complications of tibial plateau fractures?
Post traumatic osteoarthritis
Associated meniscal tears and ACL injuries
What causes patella fractures?
Direct impact injury
Eccentric contraction of quadriceps
How does an patella fracture appear on examination?
Palpable defect
If extensor mechanism disrupted then unable to perform leg raise
What causes patella dislocations?
Twisting injury with slight flexion
Direct blow to knee
Most common direction is laterally
What are common predispositions to patella fractures?
Ligament laxity Weakness of quadriceps muscles (VMO) Shallow trochlea Long patella ligament Previous dislocations
What is the treatment for patella dislocations?
Extending the knee and reducing the patella
Immobilisation
Physio to strengthen the VMO
How do meniscus injuries occour?
Sudden twisting of weight bearing knee when in high flexion
How does a meniscus tear present?
Intermittent pain localised to joint line
Clicking and locking of knee
Delayed swelling
Restricted motion
Loose meniscus fragments can act as a block to motion
How are meniscus tears treated?
If from actuate injury surgery to replace/ repair
If chronic degeneration, conservative management
What is the unhappy triad?
Injury to ACL, medical collateral ligament and medical meniscus
Due to strong force applied to knee on lateral aspect
What causes ACL injuries?
Quick deceleration and hyperextension OR rotation
Or force to back of knee when flexed
Feel a popping sensation
How do ACL injuries present?
Immediate swelling
Instability of the knee
Rotational instability as tibia rotates with PLC
How are PCL injuries caused?
Flexed knee with large force to upper tibia (dashboard injury)
Falling on flexed knee with foot plantar flexed
What test would you do for an ACL injury?
Anterior draw test
Lachman’s test
What test would you for a PCL injury?
Posterior draw test
How are knee dislocations caused?
High energy trauma uncommon injuries)
What often accompanies a dislocated knee joint?
Damage to 3 out of 4 of the ligaments (MCL,LCL,ACL,PCL)
Damage to popliteal artery (as artery immobile)
What is Housemaid’s knee a swelling of?
The pre-patella Burris
What causes housemaids knee?
Repetitive trauma to the bursa
What is clergyman’s knee also known as?
Infrapatellar burtisis
What causes clergyman’s knee?
Micro trauma from the more upright position if kneeling
What is a popliteal cyst or bakers cyst a swelling of?
Semimembranosus bursa
What causes a popliteal cyst?
Fluid accumulating as an indirect consequence of swelling within knee joint
If effusion in knee joint can force its way to posterior capsule
What causes suprapatellar bursitis?
A knee effusion
As bursa extension of synovial cavity of knee
Indicates a more significant pathology
What causes effusion of the knee?
Osteoarthritis Rheumatoid arthritis Infection Gout Repetitive micro trauma
What is Osgood-Schlatter’s disease?
Inflammation of insertion of patella ligament into tibial tuberosity
Causes localised pain and swelling (especially on exercise)
What are the symptoms of knee osteoarthritis?
Stiffness
Swelling
Pain (fluctuating levels, worsening by activities, worsened after rest)
Deformity of the knee
Crepitus (as articular surface worn away)
Effusion may develop (limit movement)
Why does the knee feel like its giving way in OA?
Weakened quadriceps muscles (joint instability)
What is septic arthritis of the knee?
Invasion of joint space by microorganisms.
Differs from reactive which is sterile inflammation resulting from extra-articular infection
What is the most common cause of septic arthritis?
Staph aureus
What increased your risk of septic arthritis?
Having prosthetic joint
(Intra operative infection or spread from distant site)
Cement used inhibits wbc growth
What is the main consequence of bacterial invasion?
Damage to articular cartilage
By;
-pathogens properties
-hosts immune response
What are the signs of septic arthritis?
Fever
Pain/ redness
Produced range of motion
