Knee Trauma Flashcards
Examples of knee trauma
-ACL injury
-Meniscal injuries
-Quadriceps
-Patellar tendon rupture
-Tibial fractures (fibula)
-Soft tissue knee
General principles of knee injury
-The knee has complex bony and soft tissue anatomy that must be appreciated in order to understand the conditions that affect it.
-Injuries to the knee are exceptionally common.
-Two symptoms are more common in knee pathology that at other sites:
=Locking - an inability to extend the knee.
=Instability – subjective or objective
Describe ACL injuries
-50% injuries in women, lateral blow to knee (sudden twisting or awkward landing)
-Typically due to pivoting
-Associated with
=Meniscal injuries: usually posterior horn of lateral meniscus acutely
=Collateral ligament injuries
Presentation of ACL injuries
-Acute
=Pain
=Sudden popping sound/ loud crack
=Swelling (haemarthrosis over minutes- hours)
-Late
=Instability, feeling that knee will give way
-High twisting force applied to bent knee
-Swelling
-Mild calor, effusion
-Anterior Drawer (should prevent forward translation movement)/ Lachmann (more reliable), pivotal shift
ACL injury diagnosis
-XR – usually done acutely
=Second Fracture = pathognomic
-MRI – can also identify associated injuries (ie. lateral meniscus)
Management of ACL injury
-ACL reconstruction with hamstring autograft (<40y/o and / or high functional demand =most patients)
-Conservative for patients with a low functional demand, poor healing intense PT
Describe the meniscus
-Fibrocartilaginous C-shaped discs that:
=Deepen the tibiofemoral articulation -> stability
=Dissipate the forces across the tibial plateau
=Move synovial fluid
-Avascular, relying on diffusion from the para-meniscal plexus (PMCP) -> poor ability to heal
-Several different morphologies, which influence management
Types of meniscal injuries
-Longitudinal tear
-Bucket handle tear
-Horizontal tear
-Radial tear
-Flap tear
-Degenerative tear
Presentation of meniscal injuries
-Pain
+/- locking
+/- intermittent swelling (delayed)
Recurrent episodes of pain and effusions are common, often following minor trauma
-Rotational sporting injuries (twisting), delayed knee swelling, recurrent episodes of pain and effusions common following minor trauma
-Swelling (mild)
-Joint line tenderness
-?locked knee when displaced/ give way
-Thessaly’s test (weight bearing at 20 degrees of knee flexion, patient supported by doctor, positive if pain on twisting knee)
Investigation and management of meniscal injury
-MRI
-Degenerative tears= conservative
-Arthroscopic (keyhole) surgery
=Partial meniscectomy (tears that cannot be repaired)
=Meniscal repair (peripheral tears, longitudinal or root)
Describe quadriceps/ patellar tendon tear (including risk factors)
-Collectively referred to as the ‘extensor mechanism’
=Mid energy fall on flexed knee for quad rupture
-Classical age distribution:
< 40 y/o = patellar tendon
> 40 y/o = quadriceps tendon
-Risk factors:
=Steroids
=DM
=CKD
=RA
Presentation of quadriceps/ patellar tendon tear
-Boggy swelling at site of tear
-Palpable ‘step’ in the continuity of the extensor
-Unable to extend the knee
Investigation and Management of quadriceps/ patellar tendon tear
-X/R +/- USS:
=Patella alta (patellar tendon tear)Or
=Patella baja (quadriceps tendon tear)
-Rx = Surgical repair
Describe tibial fractures (plateau)
-The tibial plateau is intra-articular; therefore, if fractured, blood and lipid (bone marrow) will leak from the bone into the knee.
-This may be the only sign that there is a fracture
-Lateral plateau is far more commonly fractured that the medial side
-Knee forced into valgus or varus but knee fractures before ligaments rupture
=Varus: medial
=Valgus: lateral depressed (more common)
-Lipohaemarthrosis (fluid level visible on X ray)
=Look for lipohaemarthrosis
Describe tibial fractures (diaphysis)
-Common, significant trauma in young
-Most common open fracture
-High risk of compartment syndrome
-Rx: Tibial nail
Describe tibial fractures (pilon)
-High energy fractures of the distal tibial, which involve the articular surface of the tibiotalar joint
-Not the same as an ‘ankle’ fracture
-Malignant group of injuries
Investigation and management of tibial Pilon fracture
- X/R
-CT -> all complex, intra-articular fractures benefit from a CT to aide surgical planning
-Strict elevation -> swelling +++ -> high rate of wound complications
-Ex-Fix (temporary; if there will be delay to definitive surgery)
=ORIF is definitive
-Complications: Post-traumatic osteoarthritis is common
Other ligament injuries
-Posterior cruciate: caused by anterior force applied to proximal tibia (knee hitting dashboard, hyperextension), tibia lies back on femur, paradoxical anterior draw test
-Collateral: tenderness over the affected ligament, knee effusion may be seen (medial following valgus stress, causes abnormal passive abduction of knee)
=medial: leg forced into valgus via force outside the leg. Knee unstable when put into valgus position
