Soft tissue knee injuries Flashcards
What can cause an extensor mechanism rupture?
Falling onto a flexed knee with the quads in contraction Previous tensonitis Steroid use Chronic renal failure Ciprofloxacin
What will an extensor mechanism rupture show upon examination?
Unable to straight leg raise
Palpable gap
How is an extensor mechanism rupture treated?
Requires surgical repair
What can rupture to cause a failure in the extensor mechanism of the knee?
Rectus femoris tear
Quadriceps tendon rupture
Patellar fracure
Patellar tendon rupture
What is the function of the menisci?
To distribute load from the convex femoral condyles to relatively flat tibial articular surfaces
How does the knee move over the menisci?
The knee will pivot n the medial compartment through flexion and extension
Tibia will internally rotate on flexion and externally rotate on extension
What are the different types of meniscal tears?
Longitudinal
Bucket handle
Radial
Parrot beak tear
How do the meniscus tend to tear?
Usually sporting injuries in younger patients or getting up from squatting position in younger patients
Can get atraumatic spontaneous degenerate tears in older patients (over 40)
What other ligamentous injury is commonly associated with a meniscal tear?
50% of ACL ruptures have a meniscal tear
What menisci tears more often?
Medially
How is a meniscal tear investigated?
MRI
How is a meniscal tear treated?
Only peripheral 1/3 has a blood supply
Radial tears wont heal
Consider arthroscopic reapir in acute peripheral tears in younger patients (needs extensive rehab)
When should an arthroscopic menisectomy be utilised?
Mechanical symptoms (painful catching or locking) for irreparable tears or a failed meniscal repair
How will a meniscal tear present in examination?
Acute locked knee signified a displaced bucket handle meniscal tear - 15 degree springy block to extension
What is a degenerate meniscal tear?
Common, represents 1st stage of OA
Imflammation from inital onset may settle but can be helped with steroid injections
What function does the MCL have?
Resists valgus stress (bowed)
What function does the LCL have?
Resists varus stress (knocked)
What function does the ACL have?
Resists anterior subluxation of the tibia and internal rotation of the tibia in extension
What function does the PCL have?
Resists posterior subluxation of the tibia i.e. anterior subluxation of the femur and hyperextension of the knee
What are the different grades of knee ligament injuries?
Grade 1: sprain
Grade 2: partial tear
Grade 3: complete tear
What will occur if the MCL ruptures?
Valgus instability
What will occur if the ACL ruptures?
Rotatory instability
What will occur if the PCL ruptures?
Recurrent hyperextension or instability descending stairs
What will occur if the posterolateral corner ruptures?
Varus and rotatory instability
How is an MCL injury treated?
Brace
Early motion
PT
Takes several months
How is an ACL repaired?
ACL reconstruction using autograft (hamstring or patellar tendion) or allograft (cadaveric achilles)
What sports are ACL ruptures common?
Football
Rugby
Skiing
What is the rule of thirds regarding ACL?
1/3 compensate
1/3 can avoid instability by avoiding certain activities
1/3 do not compensate and have frequent instability or can’t get back to high impact sport
When is surgery needed in ACL rupture?
Rotatory instability not responding to PT Protect meniscal repair Rapid return to professional sport Adolescent or YA Keen on high impact sport Part of multiligament reconstruction
What will ACL reconstruction not do?
Treat pain
Prevent arthritis
How will the LCL be injured?
When the leg is in varus and hyperextended
What other ligamentous injuries commonly occur with an LCL rupture?
PCL and ACL injury
How can the PCL rupture?
Direct blow to the anteiror tibia or hyperextension of the knee
Causes popliteal knee pain and brusing
What can occur with a knee dislocation?
Popliteal artery injury
Nerve - common fibular nerve
Compartment syndrome
How is a knee dislocation treated?
Emergency relocation
Check neurovascular status
Ex-fix for temporary stabilisation
Multi-ligament reconstruction
How can the patella dislocate?
Rapid turn or direct blow
Increased incidence in females - lihamentous laxity. valgus knee
Relate mechanism of injury to soft tissue damage
Valgus - MCL Twisting - ACL/ meniscal Varus - LCL Dashboard/hyperextension - PCL Getting up from squatting - meniscal
Classic history for ACL tear
Football injury, twist, pop, haemathorosis, generalised pain, pain settles after a few days
Rotatory instsability
Classic history for meniscal tear
Getting up from squatting, sudden sharp pain at the medial joint line
Effusion
Reccurent medial pain and catching +/- lockking
