LE Part 2 Flashcards
(179 cards)
How do we decide when to get a knee x-ray?
Ottawa knee rules
What are the ottawa knee rules?
- Radiograph if 1 criterion is met
- Age >55
- Tenderness at head of fibula
- Isolated tenderness of the patella
- Inability to flex knee to 90 degrees
- Inability to bear weight for 4 steps both immediately after the injury and in ED
Knee anatomy: Ligaments and menisci
What are the borders of the knee joint capsule?
- Superiorly: femur at margin of condyle
- Posteriorly: encloses condyles and intercondylar fossa
- Inferiorly: margin of tibial plateau except where tendon of popliteus crosses the bone
- Anteriorly: quadriceps tendon, patella, and patellar ligament continuous with medial and lateral margins
Knee disorders/injuries
- Ligamentous injuries
- Meniscal injuries
- Knee dislocations
What is the function of the ACL
- Primary stabilizer of the knee
- Prevents anterior translation of tibia in relation to femur
MOI of ACL tear
- Sudden deceleration with rotational trauma or hyperextension force applied to knee
Pathology of ACL tear
- Complete rupture of ligament most often occurs
- Commonly associated with a meniscal tear: MCL, LCL, or PCL rarely damaged
Presentation of ACL tear
- Twisting or hyperextension injury followed by sudden pain and giving way of the knee
- Audible pop
- Joint effusion within first few hours –> increased pain
Physical exam of ACL tear
- Joint effusion
- Limited ROM –> inability to bear full weight
- +Lachman test (most reliable)
- Anterior drawer test
- pivot shift test (only done when sedated)
Diagnostics of ACL tear
- X-ray knee series
- AP, lateral, and tunnel views
- Most often only shows effusion
- May show avulsion fracture of the lateral capsular margin of the tibia –> Segond fracture
- Tibial eminence fracture common in patients with open growth plates (avulsion)
- MRI often ordered to confirm diagnosis
How does a joint effusion appear on knee imaging?
Well-defined rounded homogenous soft tissue density within the suprapatellar recess on a lateral radiograph
Management of ACL tear
Initial
* RICE with knee immobilizer brace +/- crutches
* Pain relief –> acetaminophen before NSAIDs
* Consider aspiration if effusion large
* Start early ROM exercises as pain allows
Refer to ortho
* Young patients –> reconstruction with graft from patients patellar, hamstring, or quad tendon or cadaver
* Older patients –> PT to strengthen surrounding muscles to improve stability
What is the function of the PCL?
Prevents posterior translation of the tibia in relation to the femur
MOI of PCL tear
- Direct blow to the tibia ie knee strikes dashboard in MVA or fall onto knee
- Extreme hyperextension (associated ACL rupture)
Pathology of PCL tear
- Ranges from stretch injury to complete rupture
- Often associated with other injuries: collateral ligaments, ACL ruptures
Physical exam for PCL tear
- posterior drawer test
- Assess NV status if multiligamentous injury suspected –> assess with ABI if <.9 order arterial imaging to r/o intimal tear that could lead to thrombosis
Clinical presentation of PCL tear
- Sudden pain and giving way of knee
- Joint effusion within first few hours –> increased pain
Diagnostics for PCL tear
- Same as ACL
- X-ray knee series: AP, lateral, and tunnel views
- Often shows effusion
- May show avulsion fracture
- Tibial eminence fracture in patients with open growth plates
- MRI to confirm
Management of PCL tear
Initial
* RICE
* Knee immobilizer
* Begin ROM after 1-5 days
* Isolated PCL injuries: PT to strengthen quads and hamstrings and restore ROM and if PT fails to restore stability, reconstruction
* Multi-ligamentous injuries: reconstruction
Sequelae of PCL tear
Osteoarthritis
What is the function of collateral ligaments?
Provide stability from varus (LCL) and valgus (MCL) stress
MOI of collateral ligament tear
- Medial collateral ligament (MCL): lateral (valgus) blow to the knee
- Lateral collateral ligament (LCL): usually in association with other traumatic knee injuries
Presentation of collateral ligament tear
- Localized pain
- Tenderness
- Swelling and stiffness along ligament course
- Worsens over 6-8 hours
- Patient may be able to bear weight after injury
- 1-2 days after injury ecchymosis along ligament course and small effusion