Orthopaedic Knee Conditions Flashcards
What are the bony structures that form the knee?
Femur: medial and lateral condyles
Tibia: tibial plateau
Patella: sesamoid bone
What are the collateral ligaments of the knee? Where does each attach?
lateral collateral ligament: tip of fibula to the lateral condyle of the femur
Medial collateral ligament: originates from tibia and inserts on proximal portion of the medial condyle of the femur
Which of the collateral ligaments is attached to its corresponding meniscus?
The medial collateral ligament is attached to the medial meniscus
The LCL and lateral meniscus aren’t attached
What are the cruciate ligaments of the knee? Where does each attach?
ACL: originates at intercondylar eminence of the tibia and inserts on the medial aspect of the lateral femoral condyle
PCL: originates on the medial femoral condyle and inserts onto the posterior tibia
Describe the structure of the meniscii
C-shaped cartilage
- Triangular in cross-section: medial side thin, lateral edge wide. Results in more stability on flat tibial plateau
coronary ligaments on both meniscii (attach meniscii to joint capsule of the knee)
What are the common causes of meniscal tears? Which meniscii is more vulnerable to being torn?
Acute: twisting of knee esp. during flexion (< 40yrs)
Degenerative: osteoarthritis (60+)
Medial meniscus tears more common, probably due to more fixed shape / position
What are the symptoms of a meniscal tear?
- Pain
- Clicking
- Locking
- Intermittent swelling
What are some clinical signs on examination that are suggestive of a meniscal tear?
- Mechanical block to movement
- McMurrays test positive: bend knee and rotate foot, clicking / pain?
- Thassaly’s test positive: partially bent knee standing on that leg, rotate knee internally & externally. Pain should be on rotation to side of injured meniscus
- Patient fails to deep squat
Investigations for suspected meniscal tear?
- X-Ray: exclude arthritis / fracture
- MRI: white line within meniscus indicates tearing, high false positive rate but good sensitivity
How does the location of a meniscal tear influence its ability to heal?
The meniscus is separated into a lateral 1/3 (red zone) that is quite well perfused, and a medial 2/3 (white zone) that has limited blood supply
If the tear is more lateral, it is more likely to heal due to better perfusion
Non-operative options for meniscal tear treatment?
- Rest
- NSAIDs
- Physiotherapy (quad & hamstrings strengthening)
What type of surgery is done to repair meniscal tears?
Arthroscopy (repair / resection)
How does osteoarthritis of the knee tend to present?
Progressive pain and stiffness of the affected joint
What are some non-operative treatment options for osteoarthritis of the knee?
- Weight loss
- Analgesics
- Activity modification
- Braces / walking aids
- Visco-supplementation (hyaluronic acid)
- Steroid injections
Types of knee surgery that can be used to treat osteoarthritis?
Total Knee Replacement: (90%)
- cruciate retaining total knee replacement (retains the PCL)
- Cruciate sacrificing TKR
Uni-compartmental surgery:
- medial condyle (most common)
- Lateral
- Patello-femoral
Describe the anatomy (attachments / blood supply / innervation) of the ACL
- Originates between tibial eminences, inserts on lateral wall of intercondylar notch of femur
- Middle geniculate artery
- Posterior articular nerve (branch of tibial n.)
What movements does the ACL protect against? (function of ACL?)
- Restrains anterior movement of tibia relative to femur
- Restrains tibial rotation & varus/valgus stress
Which gender gets more ACL injuries? What type of action usually produces an ACL injury?
Females (4.5 : 1 )
- Non-contact pivot injury
How does an ACL injury tend to present?
- Patient heard a “pop” or “crack”
- Immediate swelling of joint (haemarthrosis)
- Unable to continue playing the sport. Rest for a few months then can walk normally. Movements involving twisting / turning of knee cause instability / pain
What signs should be looked for on clinical examination of a ACL tear?
- Looks for effusion
- Positive anterior draw test
- Positive Lachmann’s test
- Positive pivot shift test
Investigations for suspected ACL tear?
- X-Ray: secondary fractures
MRI:
- ACL
- Meniscii (lateral meniscal injury common)
- MCL
What are the treatment options for ACL tears?
Non-operative:
- Focused quadriceps programme
Operative:
- ACL reconstruction (usually via hamstring / patella tendon graft)
Describe the structure and function of the MCL
2 layers: superficial and deep MCL
- Superficial: primary restraint to valgus stress
- Deep: contributes to full knee extension. Attaches to medial meniscus & is continuous with the joint capsule
Presentation of MCL tear?
- Patient heard a pop / crack
- Pain (esp on medial side)
- Unable to continue playing
- Brusing of medial knee and localized sweeling
- No haemarthrosis (bleeding in joint capsule)
Signs of MCL tear on clinical examination?
- Medial swelling / bruising
- Tenderness at femoral insertion of MCL
- Painful movement in full extension
- Opening on valgus stress
Investigations for suspected MCL tear?
X-ray
- Exclude other bony injury
- Pellegrini-Stieda: calcification at femoral insertion after injury can indicate chronic damage to MCL
MRI
- gold standard, info about severity and location of injury
How are most MCL tears treated?
Conservatively:
- Rest / NSAIDs
- Physiotherapy
- Braces
In severe tears or tears that resist treatment there can be operative management
What is osteochondritis dissecans? Where does it most commonly occur?
Lesion affecting articular cartilage and the subchondral bone. Necrosis of the cartilage and bone, bone may break off
- Due to interruption of vascular supply to cartilage and bone
- Most commonly seen on posterolateral aspect of the medial femoral condyle
Presentation of osteochondritis dissecans?
- Activity related pain (poorly localized)
- Recurrent effusions
- May have localized tenderness
- Mechanical symptoms if affected bone breaks off into the joint space: locking / block to full movement
Investigations for osteochondritis dissecans?
X-Ray
- Loose bone fragment?
MRI
- lesion size, status of bone & cartilage
- Oedema? may suggest instability of bone fragment
Treatment options for osteochondritis dissecans?
Non-operative:
- Restricted weight bearing & ROM brace
Operative:
- Arthroscopy: subchondral drilling & loose fragment fixation
- Open fixation
