Orthopaedic Knee Conditions Flashcards
what is the bone anatomy of the knee?
- Femur - Distal end shaped into condyles
- Tibia - Tibial plateau, Shaped to fit condyles and movement
- Patella - Sesamoid bone
what are the key. muscles of the knee?
- Extensors - Quadriceps - Quadriceps made of 4 muscles – vastus lateralis, vastus medialis, rectus femoris and vastus intermedialis. Oblique fibres at the most distal parts are important in the control on the knee cap
- Flexors - Hamstrings
what are the ligaments of the knee?
- Cruciate ligaments - Acl and pcl
- Collateral ligaments - Mcl and Lcl
Medial collateral ligament is attached to the meniscus but on the lateral side it is not
whata re the meniscii of the knee?
- Specialised c-shaped cartilages
- Triangular in cross-section
- Medial - Attached to Deep mcl
- lateral
Thin on medial side and thicker more lateral
what is the function of the meniscii?
- Aid force transmission
- Increase stability
what are the different way meniscal tears can be caused?
- Acute - Twisting esp in deep flexion
- Degenerative - osteoarthritis
what meniscal tears are more common?
•Medial meniscal tears more common - More fixed structure
Different kinds of meniscal tears. Degenerative tears are most often seen posteriorly. Medial menisci tears are more common that lateral ones due to the medial menisci being more fixed
what is the presentation of a meniscal tear?
- Pain
- Clicking
- Locking
- Intermittent swelling
Menisci tears often in younger people, about 40s, over 60 it is often degenerative cause
what is done and found on examination of a meniscal tear?
- Look - effusion
- Feel - Tender joint line at point of tear (esp medial tear)
- Move:
- Mechanical block to movement
- McMurrays test positive
- Fail deep squat - In someone with an acute meniscal tear then cant squad down and walking that position (duck waddling)
- Thassaly’s test positive - Thassaly’s test is when they stand on one leg and rotate outwards and there is pain then it is a lateral meniscal tear but if they rotate inwards and there is pain then it is a media meniscal tear
what investigaitons may be sued for a meniscal tear? (Investigations not always necessary)
•X-ray:
- Arthritis
- Fracture
•MRI:
- Most sensitive test
- High False positive rate
a meniscal tear is unlikely to heal due to poor blood supply, what are some non-operative managements?
- Rest
- Nsaids
- Physiotherapy - Hamstring and Quadriceps strengthening
what si the operative treatment of a meniscal tear?
Arthroscopy:
- Repair
- resection
what is osteoarhtritis?
- Degenerative change of synovial joints
- Progressive loss of articular cartilage
- Secondary bony changes
how doe sosteoarhtritis present?
- Characterised by worsening pain and stiffness of the affected joint
- Limiting everyday life
what is the conservative management of osteoarthritis?
- Weight loss -Highly associated with increased weight and if this is decreased these decreases weight going through knee when going up stairs
- Analgesia
- Activity Modification
- Braces
- Walking aids
- Visco-supplementation
- Steroid Injections
what is the opeerative management of osteoarthritis?
Most arthritic knee get a TKR
2 types of TKR – in cruciate retaining the anterior cruciate is sacrificed and the posterior cruciate is kept
Medial uni-compartmental is the most common out of them, resurfacing medial part of the femur and tibia and plastic bearing in-between
Lateral uni-compartmental knee replacement are much less common
About 90% of arthritis knees need total knee replacement
what is the ACL and its features?
- 32mm length x 7-12mm width
- Runs from between tibial eminences to lateral wall of intercondylar notch of femur
- Blood Supply: middle geniculate artery
- Innervation: posterior articular nerve
- Branch of tibial nerve
what is the function of the ACL?
- Primary restraint to anterior translation of the tibia relative to femur
- Secondary restraint to tibial rotation and varus/valgus stress
how is the ACL injured and in who?
- Non-contact pivot injury
- Females : males = 4.5:1
- Landing biomechanics neuromuscular activation patterns
- quadriceps
what is the presentation of a ACL tear?
- Heard a ‘pop’ or ‘crack’
- Immediate swelling (70%) - haemarthrosis (haemorrhage into a joint space and can be regarded as a subtype of a joint effusion)
- Unable to continue playing - Can walk in straight line ()As soon as they twist or turn the knee becomes instable
- Deep pain
what would be looked for and foun don examination of a ACL tear?
- Look - Effusion (if recent injury), may involve blood
- Feel
- Move:
- Anterior draw
- Lachmann’s test
- Pivot shift - Best done under anaesthetic
what investigaitons would be done for a ACL tear?
X-ray:
•Segond fracture - Avulsion # of anterolateral ligament
MRI:
- ACL
- Meniscii
- Lateral – simultaneous with acl tear (48%)
- Medial – secondary to shear from chronic instability
•MCL
what is the treatment of a ACL tear?
Non-operative - Focussed quadricep programme
Operative - ACL reconstruction:
- +/- partial menisectomy +/- ligament repair or augmentation
- Hamstring graft
ACL repair doesn’t really work, need tissue from elsewhere so often hamstring
what is the anatomy of the MCL?
- Superficial and deep mcl
- Superficial = primary restraint to valgus stress
- Deep = contributes in full knee extension, attaches to medial meniscus, continuous with joint capsule
how do MCL tears occur?
- Severe valgus stress
- Usually contact-related
- Associated injuries:
- ACL tear
- Meniscal tear
what is the presentation of a MCL tear?
- Heard a ‘pop’ or ‘crack’
- Pain ++ - Medial side
- Unable to continue playing
- Bruising medial knee
- Localised swelling
what would be seen on examination of a MCL tear?
Look:
- Medial swelling
- bruising
Feel:
- Tender medial joint line
- Tender femoral insertion of mcl
Move:
- Painful in full extension
- Opening on valgus stress
what imaging is done for a MCL tear?
X-ray:
- May be normal
- Calcification at femoral insertion (Pellegrini-stieda) - Chronic injury
Get x-ray to exclude any other bony injury
MRI:
- Modality of choice
- Assess location and severity of injury
- Identify other pathologies
what is the non-operative treatment of a MCL tear?
- Majority
- Rest, NSAIDs
- Physiotherapy
- Brace for comfort
what is the operative treatment of a MCL tear?
- Severe tears
- Failed non-operative management
- Repair or reconstruction
- Repair: avulsions, midsubstance tear with good tissue
- Reconstruction: damaged tissue
what is Osteochondritis dissecans?
Osteochondritis dissecans (OCD) is a condition that develops in joints, most often in children and adolescents. It occurs when a small segment of bone begins to separate from its surrounding region due to a lack of blood supply
- Pathological lesion affecting articular cartilage and subchondral bone
- 2 forms:
- Juvenile - 10-15 years while growth plates still open
- Adult
Osteochondral fractures are a separate thing, osteochondritis is an area of detached bone due to limited blood supply and is not normally related to trauma
what is the most common place for osteochondritis dissecans to occur?
- Knee = most common
- Posterolateral aspect of medial femoral condyle (70%)
what investigaitons owuld be done for Osteochondritis dissecans?
X-ray - Add in tunnel view (flexed 30-50 deg) (Don’t always seen in normal view so get tunnel view)
MRI:
- Lesion size
- Status of cartilage and subchondral bone
- Signal intensity - Oedema suggests instability of fragment
what is the treamtent of Osteochondritis dissecans?
Non-operative:
- Restricted weight-bearing
- ROM brace
Operative:
- Arthroscopy - Subchondral drilling, Fixation of loose fragment
- Open fixation
