Knee conditions Flashcards
Causes of meniscal tear
Acute
- Forcefully twisting/rotating the knee - especially in deep flexion (such as aggressive pivoting or sudden stops and turns in sport etc)
Degenerative
- Osteoarthritis
How do acute meniscal tears present?
- Pain
- Clicking
- Locking - unable to extend knee
- Intermittent swelling
- Tend to present in younger people but can be seen in 40-50 y/o’s especially if they continue with sport
Examination for meniscal tear
- Look
- Effusion
- Wasting
- Feel
- Tender joint at point of tear
- Move
- Mechanical block to movement - lack of full extension
- McMurray’s test positive - not very sensitive but is quite specific
- Fail deep squat - ask patient to squat/crouch down and ask them to walk in this position - if they have a meniscal tear they can’t do this
- Thassaly’s test positive
Investigations for meniscal tear
Not always necessary to investigate
- X-ray is quite useful to exclude arthritis or fractures
- MRI - may be helpful if nothing is found on clinical examination and still need answers. Most sensitive test but high False positive rate
Why is a meniscal tear unlikely to heal?
- 2/3 of the meniscus has no blood supply (white zone)
- Red-white zone is where the blood supply is borderline
- If there is a tear in these areas then it will not heal
- If there is a tear in the red zone it can be repaired quite successfully by operative techniques
Operative and Non-operative management of meniscal tears
Non-operative
- Rest
- NSAIDs
- Physio - Hamstring and Quadriceps strengthening
Operative
- Arthroscopy - repair
- Menisiectomy - removal
Anterior cruciate ligament
One of the key ligaments that helps to stabilise the knee joint
- It gets its blood supply from the middle genicular artery
- Innervated by the posterior articular nerve - branch of the tibial nerve
How does an ACL tear occur?
Often in a non-contact pivot injury
Presentation of ACL tear
- Patients tend to know exactly when it happened - they heard a ‘pop’ or ‘crack’
- Immediate swelling of the knee - ACL is very vascular so there is an haemarthrosis
- Deep pain
- Unable to keep playing sport, can weight bear although it is painful
- Some patients may not have instability and can recover quite well where as others become very unstable
Examination of knee with suspected ACL tear
There tends to be an effusion which involves blood
May be tenderness if there is an associated injury i.e meniscal tear
Tests:
- Anterior draw - tibia is translating on the femur
- Lachmann’s test
Treatment of ACL tear
Non-operative
- Focussed quadricep programme
Operative
- Acl reconstruction
- +/- partial menisectomy +/- ligament repair or augmentation
- Hamstring graft
What is the most common ligament injury of the knee?
A Medial collateral ligament tear
How is an MCL tear caused?
- Severe valgus stress (the bone segment distal to a joint is angled outward, that is, angled laterally, away from the body’s midline)
- Usually contact-related
- Tend to have associated injuries i.e meniscal tear or ACL tear
Presentation of MCL tear
- Hear a pop or crack
- Pain on medial side
- Unable to continue playing
- Bruising on medial side of knee
- Localised swelling
Non-operative and operative management of MCL tear
Non-operative - in the vast majority even in high level sporting people they are treated conservatively
- Rest, NSAIDs
- Physio - strengthen hamstrings + quads
- Brace for comfort and to avoid strength
Operative - a small number of patients (those who do sport to high level and have several ligament damaged at same time) require surgery - usually if there is a severe tear or those who have failed conservative treatment
- Repair (avulsions) or reconstruction (damaged tissue)
What is Osteochondritis dissecans?
A pathological lesion affecting the articular surface and underlying subchondral bone. It occurs when a small segment of bone begins to separate from its surrounding region due to a lack of blood supply.
2 forms: Juvenile (when growth plates are still open) or Adult
Causes of Osteochondritis Dissecans
Not fully understood but may be…
- Hereditary
- Traumatic
- Vascular supply interrupted - adult form
How does Osteochondritis Dissecans present?
Activity-related Pain - Poorly localised
Recurrent effusions
Mechanical symptoms - if the fragment becomes loose - Locking or block to full movement
Examination/investigations of Osteochondritis dissecans
- Examination may be normal
- There may be a small effusion
- Localised tenderness
- Might be a bit stiff or a block to movement
Investigations:
- X-ray - add in tunnel view to see loose body
- MRI - lesion size, how healthy tissues are underneath
Management of Osteochondritis dissecans in the adult
Occasionally it can heal up with just conservative management:
- Restricted weight-bearing/sporting activities
- Rom brace - to restrict forces on the knee
Operative - if the loose body has dropped into the knee it needs removed also need to fix if it is in an important weight bearing area
- Arthroscopy - Subchondral drilling or Fixation of loose fragment
- Open fixation
Remember
Osteochondral fractures are completely different to osteochondritis dissecans.
Osteochondritis is an area of detached bone which is due to limited blood supply and is not normally related to trauma
Middle genicular artery diagram
