Knee problems Flashcards
History taking (what to ask about) in knee problems
Mechanism
• Swelling
- Immediate = haemarthrosis = # or torn cruciates
- Overnight = effusion = meniscus or other lgt
• Pain / tenderness
- Joint line = meniscal
- Med/lateral margins = collateral lgts.
- Locking: meniscal tear → mechanical obstruction
- Giving way: instability following lgt. injury
Causes of knee haemarthrosis
Knee Haemarthrosis
1°: spontaneous bleeding
- Coagulopathy: warfarin, haemophilia
• 2°: trauma
- ACL injury: 80%
- Patella dislocation: 10%
- Meniscal injury: 10%
- Outer third
Elements of the unhappy triad of O’Donoghue
Unhappy Triad of O’Donoghue → injury of:
- ACL (anterior cruciate ligament)
- MCL (medial collateral ligament)
- Medial Meniscus
What’s unhappy triad injury? Cause
The unhappy triad
- occurs due to a lateral blow to the knee → rupture in the anterior cruciate ligament, medial collateral ligament, and meniscus
- injury is most often sustained when a lateral (from the outside) force impacts the knee while the foot is fixed on the ground
- This type of injury occurs often in contact sports such as football, rugby, or motocross
- During the injury, the leg is laterally rotated and over-abducted
- In about 10% of cases, the force is applied to the opposite side of the knee, and the lateral and posterolateral ligaments are torn.
Treatment for unhappy triad injury
- usually requires surgery
- An ACL surgery is common and the meniscus can be treated during the surgery as well
- The MCL is rehabilitated through time and immobilization
- Physical therapy after the surgery and the use of a knee brace help speed up the healing process
Management of acutely injured knee
- Full examination of acutely swollen knee after injury is difficult
- Take x-ray to ensure no fractures
- Fluid level indicates a lipohaemarthrosis and
indicates either a # or torn cruciate
- If no # → RICE + later re-examination for pathology
- If meniscal or cruciate injury suspected → MRI
What’s arthroscopy?
- Direct vision of inside of knee joint by arthroscope
- Can examine knee under anaesthesia (↓ muscle tone)
- Meniscal tears can be trimmed or repaired
Ruptured Anterior Cruciate Ligament
- mechanism
- typical presentation
- management
- Sport injury
- Mechanism: high twisting force applied to a bent knee
- Typically presents with: loud crack, pain and RAPID joint swelling (haemoarthrosis)
- Poor healing
- Management: intense physiotherapy or surgery
Ruptured Posterior Cruciate Ligamanet
- mechanism
- examination findings
- management
- Mechanism: hyperextension injuries
- Tibia lies back on the femur
- Paradoxical anterior draw test → posterior draw test positive
- Management:
- conservative: aspiration of haemarthrosis, analgesia and physiotherapy
- arthroscopic repair
Rupture of medial collateral ligament
- mechanism of injury
- management
- Mechanism: leg forced into valgus via force outside the leg
- often as part of unhappy triad
- Knee unstable when put into valgus position
Management:
- immobilisation in cast for 6 weeks
OR
- surgical reconstruction
Meniscal tear
- cause
- presentaiton
- management
- the majority would involve medial meniscus
- traumatic or degenerative causes; rotational sport injuries
Presentation:
- Delayed knee swelling
- Joint locking (Patient may develop skills to ‘unlock’ the knee
- Recurrent episodes of pain and effusions are common, often following minor trauma
Management:
- arthroscopy and partial meniscectomy (total is too risky in terms of premature osteoarthritis) + meniscal repair
Dislocation of patella
- mechanism
- Most commonly occurs as a traumatic primary event, either through direct trauma or through severe contraction of quadriceps with knee stretched in valgus and external rotation
- Genu valgum, tibial torsion and high riding patella are risk factors
Ix for dislocated patella
- Skyline x-ray views of patella are required, although displaced patella may be clinically obvious
Management of patellar dislocation
- Conservative treatment (rehabilitation and physical therapy)
- surgery
What’s McMurray’s test?
Test for meniscal tear
- unreliable and difficult
- performed when joint line tenderness is present
Knee is fully flexed + foot externally rotated (with lower leg abducted)
If the knee is extended + click and pain over medial joint line → meniscal tear
