The Knee Flashcards
What are the 3 compartments of the knee?
- Patello-Femoral compartment
- Medial Tibio-Femoral compartment
- Lateral Tibio-Femoral compartment
List 3 things which stabilise the knee joint
ligaments, capsule and muscles
Using the mnemonic “SLIP”, how do we take a knee history?
- Swelling
- Locking ➞ meniscal tears, loose bodies
- Instability (giving way) ➞ ligament problems (eg ACL tear), patellofemoral problems
- Pain
- Site - medial/lateral/anterior/posterior
- exacerbating factors
- mechanical, rest or night pain
Exacerbating factors such as stairs or hills are associated with what knee problems?
Patellofemoral disorders
If a patient presents with knee pain, but examination and investigation are unremarkable… what MUST we consider?
Hip and/or spine problems!
Pain is commonly referred to the knee from the hip and/or spine
What questions must we ask in a history of a sports injury?
- Mechanism of injury
- Pivoting/non-pivoting
- Contact/Non-contact
- Direction of impact (varus/valgus/anterior etc)
- Deformation
- Swelling immediate or delayed
- Haemarthrosis (occurs within 90 minutes)
- Effusion (occurs after 6-12 hours)
- Able to finish the activity ?
What are we looking for in a knee examination?
What are we feeling for in a knee exam?
- Temperature
- Swelling
- Tenderness
- Crepitus
Which tests would be used to assess small/moderate/large amounts of joint effusion in the knee?
Small - “bulge test”
Moderate - patellar tap
Large (tense) - ballotment
What are we testing when we move the knee in an examination?
List 3 special tests which can be used to assess the ACL
Lachman’s test (Most sensitive for ACL rupture)
Pivot Shift
Anterior drawer
List 2 special tests which can be used to assess the PCL and explain each
- Posterior sag ➞ In supine position, hip and knee are flexed to 90°. Examiner supports leg in the air.
* Positive sign is a posterior sag of the tibia caused by gravitational pull - Posterior drawer ➞ same as Anterior drawer BUT tibia is pushed back
How do we test the medial and lateral collateral ligaments?
Valgus stress test (MCL) and Varus stress test (LCL)
Performed at 20° flexion AND at full extension
Move the knee from side to side and assess the amount of opening (always slightly more movement laterally).
Check for an end point, there should not be over opening or pain. If there is either, it indicates CL problem
What does this X-ray show?
Medial Collateral Ligament Rupture
X-ray shows huge opening of medial side of joint
What “One Special Test” is used to test each ligament of the knee?
ACL – Lachman @ 20o
PCL – (Sag) + Posterior Draw @ 90o
MCL – Valgus @ 20o
LCL – Varus @ 20o
What 2 tests are used to assess for a medial or lateral meniscal tear?
- McMurray’s test
- Appley’s ➞ Grinding and distraction tests
If pain is ellicited in either test it indiactes tear
What 2 tests can be used to assess the Patellofemoral Joint?
- Patellar glide test (Sage sign)
- Knee at 30o flexion
- Translate patella medially and laterally
- Patellar apprehension test
- Push patella laterally with the knee at 30o flexion
- If positive patient will react with apprehension or try to push examiner away
List 4 investigations we can do for knee pathologies and when each is indicated
- X-ray ➞ fracture, arthritis
- MRI Scan ➞ meniscal tear, ACL and CL ruptures
- Aspiration (culture and cytology) ➞ gout, pseudogout
- Blood tests ➞ rhumatological fators
What does the X-ray below show?
Explain this pathology
Pseudogout (Chondrocalcinosis)
Calcium pyrophosphate deposition on soft tissue, here it is on both the medial and lateral meniscus
What is Osteochondritis Dessicans (OCD)
Occurs when a small segment of bone begins to separate from its surrounding region due to a lack of blood supply
As a result the small piece of bone, and the cartilage covering it begin to crack and loosen
What structure and age group is most commonly affected by Osteochondritis dissecans?
Usually afftects the medial femoral condyle of the distil femur and occurs in children
What is the treatment for Osteochondritis Dessicans?
Conservative ➞ rest, NSAIDs, Intra-articular steroid, splint/orthotics, physiotherapy, modification of activity, weight loss
Operative ➞ arthroscopic/open, excision/repair of meniscus, removal of loose body, ligament reconstruction, patella realignment, osteotomy, joint replacement (partial/total)
Give 5 features of patient history/presentation which may indicate ACL rupture
- Severe pain
- Immediate swelling (within 1 hour)
- Says they did not finish the game
- Sudden ‘popping’ sound on injury
- Tenderness is uncommon
In a suspected ACL rupture, what does a history of immediate swelling tell us and why?
Haemarthrosis (80% assoc ACL rupture) as the ligament is highly vascular, hence rupture results in a haemarthrosis
What are the 2 ways in which ACL ruptures usually occur and which is the most common?
- Pivot, non contact ➞ abrupt stopping or changing of direction (most common)
- contact-related ➞ knee forced into hyperextension
In an ACL rupture, usual presentation may be delayed. What else may the patient experience meanwhile?
Instability may be evident, in which the patient describes the leg ‘giving way’ recurrently
ACL ruptures are often associated with what?
Meniscal damage
Give 5 features of patient history/presentation which indicate a Meniscal Tear?
- ‘tearing’ sensation in their knee
- Intense sudden-onset pain, rarely finished game
- delayed swelling (4-6 hours)
- knee may be locked in flexion
- Joint line tenderness (good predictor of meniscal tear)
What is the recovery of a meniscal tear?
What may be an indication for surgery?
Most small tears will initially swell but the pain will subside over the next few days as the tear heals.
Larger tears or those who experience recurrent locking or persistant pain may require surgery (arthroscopy)
How do meniscal tears usually occur?
Activities that cause direct contact or pressure from a forced twist or rotation ➞ sudden pivot or turn, deep squatting, heavy lifting
Can also be caused by degerative diseases
Which meniscus is more prone to tearing and why?
The medial meniscus as it is tethered to the MCL and joint capsule medially. The lateral meniscus is much more free
What knee conditions/pathologies are associated with the following:
- children
- sports injurys
- seniors
What is shown on the X-ray below?
Explain this pathology
Severe osteoarthritis affecting the medial compartment of the right knee (osteophytes, slerosis, cysts, loss of joint space)
Moderate osteoarthritis affecting the medial compartment of the left knee
How do we assess which treatment is needed for knee osteoarthritis
History and evaluation of the following:
- mechanical, rest and/or night pain?
- walking distance?
- analgesia requirements?
- response to conservative measures?
- associated medical conditions?
If all conservative measures for knee osteoarthritis fail, what is our surgical option?
Total Knee Replacement
