Knee Flashcards
Ottawa Knee Rule
1) Age older than 55 years
2) inability to transfer weight from one foot to the next four times at the time of injury and in the ED
3) inability to flex the knee to 90 degrees
4) patella tenderness with no other bone tenderness
5) tenderness of the fibular head
any of the above positive should have an x-ray
DIscuss knee dislocations
Limb threatening emergency
Tibriofemoral dislocation
By definition are asscoiated with significant ligamentous injury. Usually both cruciates and a single collateral. The joint capsule is disrupted with accompanying trauma to the muscles and tendons. Injury to the popliteal artery is the msot severe complications and is the primary cause of morbidity and limb loss
The neurovascular bundle pop art, vein and common peroneal nerve run together and are all at risk of injury
Anatomically dislocations are described according to the deplacement of the tibia relative to the femure. They are classified into 5 types
- ant
- post
- medial
- lateral
- rotary
Discuss evaluation of knee dislocations
Half of all knee dislocations self reduce prior to arrival in the ED – evaluation for pop artery injury should be undertaken regardless
Anyone with known knee dislocations, multiligamentous injury or high impact trauma to the knee should be evaulated
Ankle brahcial index (ABI) the ratio between BP at the humeral location and measured at the ankle of more than 0.9 has a NPV appoching 100%
CTA and duplex ultrasound are other forms of investiations
Discuss management of knee dislocations
Reduction at the earliest opportunity
Neurovascular status evaluated before and after reduciton
Most will be unstable and should be immobilised with the knee in 15-20 degrees of flexion
Discuss complications of knee dislocations
Acute
-neurovascular compromise
Delayed
- DVT
- compartment syndrome
- pseudoaneurysm
- arterial thrombosis
Describe distal femur fractures
Uncommon High energy mechanism is required Acute haemarthrosis is common Painful; femoral nerve blocks are useful Traction bed
Complications
- thrombophlebitis
- fat embolus syndrome
- delayed unioun
- non union
- malunion
- angulation deformity
- arthritis
Describe tibial plateau fractures
Usually are intra-articular fractures
Forces that act on the tibial condyles include axial compression and rotation. The most common mechanism of injury is a strong valgus force with axial loading.
Describe Segond fractures
The segond fracture represent a bone avulsion of the lateral tibial plateau - occurs at the attachement site of the lateral capsular ligament. Usually accompanied by ACL disrutpion and anterolatearl rotatory instbaility
Discuss clinical finding and ix of tibial platuea fractures
Pain tenderness, ecchymosis soft tissue swelling and haemoarthorsis when intrarticular.
Plain film - underestimates injury
-lipohaemarthrosis seen as a fat fluid level on a plain film suggest an occult fracture and is caused by entry of marrow fat into the joint space
-widened joint space
-sclerotic band of bone indicating compression fracture
pleurae not smooth
Tibial margin displacement
CT more sensitive
Discuss management of tib platue fractures
Ortho
Otherwise non circumferential cast and non weight bearing for 6-8 weeks
Describe fractures of the intercondylar eminence (tibial spine)
The central portion of the proximal tibial survace. The ACL and anterior horns of the medial and lateral menisici attach in the anterior intercondylar fossa. The PCL and posterior horns of the menisci attach in the posterior intercondylar fossa.
Is usually associated with an ACL rupture
More common in children than in adults becuase the ligaments are stronger than the adjacent physeal plates in the immature skeleton
Most occur due to results of violent knee twisting, hyperflexion hyperextension or vlagus varus forces generated during MVCs
DIscuss factors that increase vulnerability to tendon rupture
- RA
- SLE
- Hyperparathyroidism
- iatrogenic immunosuppresion in organ transplant
- fluroquinoloenes
Discuss clinical features ix and management of extensor mechinism rupture (patella tendon ruputre)
1) acute pnset of pain swelling and ecchymoses over the anterior aspect of the knee and a palpable defect in the patella, quadricpes or patella tendon
2) loos or limitation of ability for active leg extension
- extension alg usually is seen when extension for the last 10 degrees is performed haltingly or with difficulty
3) high riding patella with patella rupture
4) low riding patella with quadriceps rupture and inferior retraction.
Plan films
MRI
US
Management
- early intervention is associated with better outcome
- for partial tears immobilisation in full exxtension for 4-6 weeks
- surgical intervention is required for attachement of complete tendon ruptures and repair should be performed as soon as possible after injury
Discuss management of patella dislocation
Reduce
Immobilise in full extension for 2 weeks
Describe ACL rupture
Extends obliquely upward medially and postriorly from the anterior intercondylar area of the tibai to the medial aspect of the lateral femoral condyle. It prevent excessive anterior displacement of the tibia on the femur and helps control rotation and hyperextension.
Most commonnly due to non contact sport with the plant and pivot and stop and jump mechanisms
Half of ACL injuries are associated with meniscal tears with the lateral being torn more commonly than the medial in acute but in chornic the medial are more commonly involved.
Describe PCL rupture
Prevent excessive poeterior displcament of the tibia on the femur esepcially druing flexion. The PCL is extremely strong and injuries are relatively uncommon.
Mechanisms
-falling onto the ground with the floot plantar flexed, direct posterior blow to a flexed knee, hyperflexion, hyperextension, severe varus or valgus loads after failure of the collaterals and knee dislocations.
Nearly all PCL are associated with other ligamentous injury
Describe collateral ligament rupture
Medial stabilisers are the joint capsule and the MCL
MCL is usually injured by a direct blow or impact to the lateral aspect of the knee. The MCL is the most commonly isolated ligamentous injury of the knee
Does not usually require surgical management
Lateral stabilizers of hte knee are the LCL and lateral joint capsule.
Hyperextension with varus stress and less commonly a direct blow or rotation is mechanism
-common peroneal nerve and biceps femoris tendon injury are possible though rare with LCL injuries
Discuss ED management of acute ligamentous injury to the knee
Compressive dressing from the foot to thigh
RICE
No weight bearing
ortho review within a week
Discuss specific examination test for knee injury
Anterior draw test
-ACL
-positive test as greater anterior movement of the tibia
as compared to the other knee
Posterior draw test
- PCL
- posterior displacement of the tibia more than 5mm or a soft endpoint indicates injury to the PCL
Posterior sag sign test
- PCL
Collateral stress test
McMurrays test
- Supine position with the knee hyperflexed
- grasp the foot with one hand and the knee with the other.
- Examiner flexes and extends the knee while simulateneously internally and extenrally rotating the tibia on the femur
- positive test results is the occurance of clinking palpable along the joint line or locking of the knee
Apley
- knee is flexed to 90 degrees and the leg is internally and externally rotate with pressure applied to the heel
Pain eleccited by downward pressure suggest meniscal pathology
Describe tibial tubercle fractures
Avulsion fractures of the tibial tubercle are uncommon.
Occur mainly as an indirect injury during acitivity. The mechanisms of injury has been described as a violent flexion of the knee against a tightly contracted qauds
The watson jones classification describes three grade of injury
- type 1 the tubercle is hinged upward without displacement from the proximal base
- type 2 injury has a small portion of the tubercle avulsed buyt its retracted proximally the articular surface is not involved
- type 3 are more severe and extend across the articular surface displacement of the fragment and often comminution are feature.
Type 1 and 2 are treated with cast until healing is comlete
Type 3 requires ORIF
complications are rare
- genu recurvatum
- patella alta
- meniscal tear
Describe tibial shaft fractures
The tibia and fibula are tightly bound to each other by the syndesmotic ligament. This strong band of tissue can transmit energy so that the tibia and fibular may be fractured in nonadjacent sites
The fibula remains intact in only 15-25% of tibial shaft fractyres
Vascular injury is rare however neurological injury is quite common with the peroneal nerve being damaged frequently - this is check by testing active anle toe dorsiflexion (deep peroneal nerve) and active foot ecersion (superficail peroneal nerve)
Initial management is long leg cast with 10-20 degrees of flexion.
Discuss proximal fibular fractures
Isolated fibular fractures are relatively unimportant because the fibula is a nonweight bearing bone.
common peroneal nerve can be injured in this type of fracture
Be aware of maisonneuve fractures which involve the deltoid ligament and the syndomosis and cayuse the fibular to be “floating” - look for tib fractures in this case
Describe the Schatzker system
Used to describe tibial plateau fractures
Type 1 - latearl tib splitting without dpression
Type 2 - latearl tib splitting with depression
Type 3 - lateral tib isolated depression
- a – lateral depression
- B – central cepression
Type 4 medial tib with splitting or depression
Type 5 Both plateaus
Type 6 Transvers tibial metadiaphyseal fracture with any other tib plat facture
Fracture 1-3 are lateral involving varying degrees of depression
Fracture type 4 involves the medial plateua
Fracture type 5 and 5 involve both plateaus with increasing communution and joint instability
