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.
