Knee Flashcards
What could cause a haemarthrosis in the knee?
ACL
Fracture
What is likely to cause an effusion?
Meniscal or chondral injury
If there is pain in the joint line, what might this be?
meniscal/chondral
How can you check for effusion/haemarthosis?
Wipe test
Patellar ballottement
Gap in extensor mechanism?
Quad or PT rupture
Pain in the joint lines?
Meniscus
Pain on the bony prominences?
Fracture
What does straight leg raising assess?
The integrity of the extensor mechanism
Meniscal provocation test?
McMurrays
-Pain or palpable click suggests meniscal tear
Movements to check knee?
Straight leg raise (extensor mechanism)
Extension (springy block to full extension indicated locked knee-displaced bucket handle tear)
Flexion
Ligament Tests
May be difficult in acute setting
Look for abnormal laxity compared to contralateral knee and for end point
When checking for MCL and LCL injuries, why do you flex the knee to 30º?
To relax the posterior capsule
Which ligament tear does the Lachman test look for?
Anterior cruciate ligament
Tests for anterior cruciate ligament?
FIRST, check no posterior sag (PCL, would give false positive)
Lachman test at 30º
Anterior drawer test at 30º
Tests for posterior cruciate ligament?
Posterior sag at 90º
Posterior drawer test at 90º
If you have a suspected tibial plateau fracture, what investigation should you carry out?
CT
Investigation for fracture/bony avulsion?
X-ray
What are 50% of ACL tears associated with?
How would you investigate?
50% of ACL tears are associated with meniscal tears
Investigate with MRI
What could happen if a bucket handle tear isn’t repaired?
Could develop a fixed flexion deformity
The 3 grades of ligament tear?
Grade 1: some fibres tear but macroscopic structure still in tact
Grade 2: partial tear with some fascicles disrupted
Grade 3: complete tear
Surgery for MCL tear?
- usually heals well even if complete tear unless combined with ACL or PCL rupture
- brace, early motion, physio
- Pain can take several months to settle
- If combined ACL & MCL rupture may consider early ACL reconstruction + MCL repair
-Rarely requires surgery – advancement or reconstruction with tendon graft
Which ligament is the main stabiliser against internal rotation of the tibia?
ACL
ACL rupture
ACL is main stabiliser against IR of tibia
Usually sports injury – football, rugby, skiing
ACL repair doesn’t work reconstruction only
Autograft – Patellar tendon or hamstrings
Allograft – Achilles
(synthetic graft)
ACL can stick to PCL to give some stability
Physio can stabilise ACL deficient knees
Which nerve is commonly damaged following an LCL injury?
Common peroneal nerve palsy
How quickly should you aim to repair LCL tears?
You should aim to repair them quickly (i.e. within 2-3 weeks)
If you repair them later, you are probably going to have to do a reconstructio
An injury to which ligament to lead to a feeling of instability when going down the stairs?
PCL
Wn injury to which ligament could present with popliteal knee pain and bruising?
PCL
Is a PCL injury usually isolated?
No, usually occurs with other injury
Complications of high energy knee dislocation?
- Popliteal artery injury
- Common peroneal nerve injury
- Compartment syndrome
How might you dislocate your patellar?
Rapid turn or direct blow
Extensor mechanism rupture?
- Falling onto flexed knee with quads contraction
- Previous tendonitis
- Steroids
- Chronic renal failure (CIPROFLOXACIN)
Which test can people with extensor mechanism rupture not do?
The can’t do a straight leg raise and there is a palpable gap
-Needs surgical repair
If you fall onto your knee with quad contraction what might happen?
You might rupture your extensor mechanism
How might an osteochondral injury heal?
It may heal with fibrocartilage
- If not, you can do surgery (drilling, microfracture, culture, osteochondral plugs)
- Surgery only for smaller lesions and NOT OA
What does the PCL prevent?
PCL prevents hyperextension and anterior translation of femur
What is the principle role of the ACL?
To prevent internal rotation of the tibia
What is the function of the LCL?
The LCL prevents external rotation of the tibia, it also prevents against varus force
Effusion, joint line tenderness, pain on tibial rotation, localising to the affected compartment?
Meniscal tear
Meniscal tear
Effusion, joint line tenderness, pain on tibial rotation localising to the affected compartment (Steinman’s test)
Why are medial meniscal tears more common than lateral meniscal tears?
The medial meniscus is more fixed and less mobile than the lateral meniscus and the force from pivoting movements is centred on the medial compartment
Which part of the meniscus has a blood supply?
The outer 1/3rd of the meniscus has a blood supply
therefore, the meniscus has limited healing potential
Healing potential also decreases with age (over about 25-30, healing rates are poor) and with increased time from injury
Which type of meniscal tear should be considered for surgery?
Longitudinal in the outer 1/3rd of the meniscus in a younger patient
Repair involves suturing the meniscus to its bed
(25% of repairs still fail though and require arthroscopic menisectomy)
Principle complaint of ACL?
Rotatory instability with giving way on turning
What does the PCL do?
PCL prevents hyperextension and anterior translation of the femur
Approximately what percentage of patients suffer from unexplained pain following a TKR?
15%
Which is harder, a TKR or revision of knee replacement surgery?
Revision surgery is a bigger undertaking than the original TKR
