Soft tissue knee injuries Flashcards
What are the two collateral ligaments of the knee?
Lateral collateral ligament
Medial collateral ligament
What are the two cruciate ligaments of the knee?
Anterior cruciate ligament
Posterior cruciate ligament
What are the two meniscus of the knee?
Medial meniscus
Lateral meniscus
Which bones are involved in the knee joint?
Femur
Tibia
Fibula
Patella
What are the two fibres which compose the meniscus?
Longitudinal fibres
Radial fibres
Describe the blood supply to the meniscus
Only the most peripheral 1/3 of the meniscus has a direct blood supply
Are medial or lateral meniscal tears more common? Why?
Medial. The medial meniscus is under a greater amount of sheer stress
What is the function of the menisci?
Distribute load from the convex femoral condyles to the relatively flat tibial plateaus
Why does the medial meniscus undergo a greater amount of sheer stress?
Knee pivots on medial compartment of the knee during flexion and extension
Which is more mobile the lateral or medial meniscus?
Lateral meniscus (medial is fixed)
How does the tibia move during flexion and extension?
Flexion - internal rotation
Extension - external rotation
Which forces do the collateral ligaments resist?
Medial - valgus stress
Lateral - varus stress
Which forces do the cruciate ligaments resist?
Anterior - anterior subluxation of tibia & internal rotation of the tibial in extension
Posterior - posterior subluxation of the tibia (i.e anterior subluxation of the femur and hyperextension of the knee)
Which structures resist external rotation of the tibia in flexion?
Posterolateral corner - posterior cruciate, lateral collateral and popliteus
Describe the anatomy of the medial collateral ligament
Broad and thin
Excellent blood supply
Describe the anatomy of the lateral collateral ligament
Thick and cord like
Poor blood supply
Which collateral ligament of the knee usually heals on its own?
Medial
What type of instability does medial collateral ligament rupture cause?
Valgus
What type of instability does anterior cruciate ligament rupture cause?
Rotatory instability
What type of instability does posterior cruciate ligament rupture cause?
Recurrent hyperextension
Difficulty descending stairs
What type of instability does posterolateral corner rupture cause?
Varus
Rotatory
What are the types of meniscal tears?
Longitudinal
Radial
Bucket handle
Parrot beak
Which type of meniscal tear can cause knee locking?
Bucket handle
Which type of meniscal tear may heal on its own?
Longitudinal (if very peripheral)
What is the typical history of meniscal tears in younger patients?
Traumatic - sporting injury / getting up from squatting
What is the typical history of meniscal tears in older patients (>40)?
Atraumatic degenerative
What are meniscal tears associated with?
ACL rupture
How are meniscal tears investigated?
MRI
How can peripheral tears be managed?
Arthroscopic repair in younger patients with extensive rehab
(often fails)
How does the pain progress with meniscal tears?
Initial pain may settle
When is an arthroscopic menisectomy considered for meniscal tears?
Mechanical symptoms (painful locking)
Irreparable tears
Failed repair
How do you know which menisci you’re looking at on an MRI?
Look for the bones - if tibia then probably medial meniscus
What is the cause of an acute locked knee?
Displaced bucket handle meniscal tear
How does a displaced bucket handle meniscal tear present?
Springy 15 degree block to extension
How should a displaced bucket handle meniscal tear be managed? Why?
Surgery (arthroscopic repair or partial menisectomy)
Prevent further damage to knee joint and resolve locking
What may develop of a displaced bucket handle meniscal tear is not treated?
Fixed flexion deformity
What can be seen on an MRI that indicates meniscal tear?
Double PCL sign
Gap in meniscus
How common are degenerative meniscal tears?
Common
How do degenerative meniscal tears present?
Often asymptomatic
How should degenerative meniscal tears be managed?
Conservatively (pain will settle)
Injection to help pain
Surgery for mechanical symptoms (NOT PAIN)
Describe the grading system of ligament tears
Grade 1 - Sprain (macroscopic structure intact)
Grade 2 - Fascicles disrupted
Grade 3 - Complete tear
What is the typical history of a medial collateral ligament tear?
Valgus stress (sport tackles, etc)
How are MCL tears managed?
Bracing
Early motion
Physiotherapy
Surgery if combined injury/unstable knee
What are the surgical options for MCL tears?
Advancement
Tendon graft
How does the pain progress with MCL tears? Why?
Can take several months to settle
MCL has good innervation
What is the typical history of an anterior cruciate ligament tear?
Sports (rugby, football, skiing)
Twisting injury
How are ACL tears managed?
Bracing and/or Physiotherapy (elderly) Surgical reconstruction (younger)
What are the different surgical approaches to ACL tears?
Autograft - hamsting or patellar
Allograft - achilles
How can the ACL self stabilise?
By sticking to the PCL
Describe the rule of 1/3rds as it relates to ACL tears
1/3 - compensate
1/3 - compensate if avoiding certain activities
1/3 - cannot compensate and cannot return to high impact sport
Which type of patient is more likely to compensate following and ACL rupture?
Older (+ more likely to avoid impact sport)
What are the indications for ACL surgery?
Younger High impact sport High demand Rotatory instability not responding to physiotherapy Protect meniscal repair Part of multi-ligament repair
What does ACL surgery not do?
Treat pain
Prevent arthritis
What are the possible consequences of ACL tear and surgery?
Stiffness
Infection
Donor site morbidity
Post traumatic arthritis
How common is lateral collateral ligament tear?
Uncommon
What is the typical history of LCL tear?
Varus forces
Hyperextension injury
Does the LCL heal?
No
What are the consequences of a non-healing LCL?
Varus and rotatory instability
What is associated with LCL tear?
Common peroneal nerve injury
ACL rupture
PCL rupture
How is LCL tear managed?
Surgical repair (caught early) Surgical reconstruction (caught late)
What is the typical history of a posterior cruciate ligament rupture?
Direct blow to anterior tibia (dashboard, motorcycle)
Hyperextension injury
How might a PCL tear present?
Popliteal pain and bruising
How common is a PCL tear?
Uncommon in isolation
How is PCL tear managed?
Conservative if isolated
Surgical reconstruction if marked instability or as part of multi-ligament reconstruction
How does PCL instability present?
Instability when going down stairs
Recurrent hyperextension
Is knee dislocation a high or low energy injury?
High
Knee dislocation has a high incidence of complications. What are these?
Popliteal artery injury (intimal tear, thombosis)
Common peroneal nerve injury
Compartment syndrome
How should a knee dislocation be managed?
Emergency reduction
Neurovascular status +/- vascular surgery
Ex-fix for temporary stabilisation
Multi-ligament reconstruction
What is the typical history of a patellar dislocation?
Sudden turn
Direct blow
Who is most at risk of patellar dislocation?
Females Ligament laxity Valgus deformity Adolescents Torsional abnormalities
What is the risk of recurrent dislocation of the patella?
Low (10%)
Patellar dislocation can cause chondral or osteochondral damage. T/F
True
How is patellar dislocation treated?
Conservatively
Rarely surgical stabilisation
What is the typical history of a extensor mechanism rupture?
Fall onto flexed knee with quadriceps contraction
Who is at highest risk of extensor mechanism rupture?
Steroids Chronic renal failure Ciprfloxacin Previous tendonitis Rheumatoid arthritis
What should be found on examination of a patient with extensor mechanism rupture?
Unable to straight leg raise
Palpable gap
High or low riding patella depending on injury site
How is extensor mechanism rupture treated?
Surgical repair
Which ligament rupture will commonly cause a pop or crack?
ACL
Which injuries will produce a haemarthrosis?
ACL
Fracture
Which injuries will produce an effusion?
Meniscal
Chondral
How will a haemarthrosis be described in the history?
Sensation of filling up
