soft tissue knee injuries lecture Flashcards
Which menisci is under greater stress and why?
Medial meniscus under greater amount of shear stress - Due to shape and soft tissues, knee pivots on medial compartment through flexion and extension.
What is the function of the MCL ?
Resists valgus stress
What is the function of LCL?
Resists varus stress
Whta is the function of the ACL?
Resists anterior subluxation of the tibia and internal rotation of the tibia in extension
What is the function of the PCL?
Resists posterior subluxation of the tibia ie anterior subluxation of the femur and hyperextension of the knee
What area resists external rotation of the tibia during flexion and what are the main structures which form this area?
The posterolateral corner – the PCL and LCL with popliteus and other smaller ligaments resist external rotation of the tibia in flexion
What may MCL rupture lead too?
vlagus instability
What may posterolateral corner rupture lead too?
Recurrent hyperextension or instability descending stairs
What vwould be seen if multiple ligaments are ruptured?
gross instability
Why can a longitudinal cartilage tear be repaired but a bucket handle tear cannot ?
Because the peripheral 1/3rd of cartilage has a blood supply hence longitudinal tears can be repaired and bucket handle ones cannot
Which menisci is more commonly torn?
the medial (10X’s more likely)
What do people who rupture their ACL commonly also injure?
approx 50% also have menisci tears
What is the common mechanism for meniscal injury?
Usually sporting injury in younger patients or getting up from squatting position in younger patients
In older patients (over 40) what type of meniscal injury are they also at risk of ?
Atraumatic spontaneous degenerate tears
What test is done to confirm the diagnosis of a meniscal injury?
MRI
Will radial catilage tears repair ?
No
In an acute peripheral cartilage tear in a younger patient what could be considered ?
Arthroscopic repair - up to 40% failure rate
For a meniscal tear which is irreparable or a failed meniscal repair - in which the patient is experiencing painful catching or locking, what could be considered to treat this ?
Arthroscopic menisectomy for mechanical symptoms
What does an acute locked knee signify ?
A displaced bucket handle meniscal tear -Patient will have 15 degree springy block to extension
Describe the classification of grading knee ligament injuries
- Grade 1 – sprain – tear some fibres but macroscopic structure intact
- Grade 2 – partial tear - some fascicles disrupted
- Grade 3 – complete tear
Which ligament in the knee has a good blood suplpy and hence even when ruputured rarley requires surgery?
MCL usually heals well even if complete tear unless combined with ACL or PCL rupture
What is the usual treatment for an injury to the MCL?
- Brace
- early motion
- physio
When is the ACL usually injured ?
Usually sports injury – football, rugby, skiing
What is the treatment for an ACL rupture?
Usually reconstruction using:
- Autograft – Patellar tendon or hamstrings
- Allograft – Achilles
- (synthetic graft)
Physio can also stabilise the knee
What is the rule of 1/3rds in ACL rupture?
n1/3 compensate and are able to function well
n 1/3 can avoid instability by avoiding certain activities
n 1/3 do not compensate and have frequent instability or can’t get back to high impact sport
What are the reasons for carrying out an ACL reconstruction ?
- Rotatory instability not responding to physio
- Protect meniscal repair
- Rapid return to professional sport or high demand job
- Adolescent or young adult - ?more reliable option
- Keen on high impact sport
- As part of multiligament reconstruction
What is the duration of rehab following an ACL reconstruction ?
3/12 to 1 year
After 10 years following an ACL reconstruction what do patients usually have on radiograph?
Arthritic changes
Injury to LCL causes what?
varus instability and hyperextension
In LCL injury what nerve is commonly damaged ?
High incidence common peroneal nerve palsy
What does injury to LCL commonly occur with?
PCL or ACL injury
What is the treatment for LCL rupture ?
- Complete rupture needs urgent repair if early (within 2-3 wks)
- Later à reconstruction (hamstring or other tendon)
What is the common mechanism for injury to the PCL ?
Direct blow to anterior tibia, (Dashboard / Motorbike) or hyperextension injury
Is it common to have an isolated rupture to the PCL ?
No - usually occurs with other injury
If the PCL rupture is isolated what is usually the treatment plan ?
If PCL is involved in mutliligamenty injury what is the treatmeant ?
if isolated - often doesn’t require reconstruction so physio
If mutliligament - requires reconstruction followed by physio
Knee dislocation is a serious high energy injury with high incidence complications, what are some of these complications ?
- Popliteal artery injury (tear, intimal tera & thrombosis)
- Nerve injury – common peroneal nerve
- Compartment syndrome
- Multiligament injury
What is the treatment for knee dislocation ?
emergency reduction, recheck neurovascular status.
if concerns with vascular status may need vascular surgery
What may need to be done to stablise the knee after dislocation ?
May need ex fix for temporary stabilisation
What ligament holds the patella in place ?
MPFL (Medial patellofemoral ligament)
What is the common mechanism for patellar dislocations?
Rapid turn or direct blow
What factors predispose patients to soft tissue knee injuries?
- Previous tendonitis
- Steroids
- Chronic renal failure, Ciprofloxacin
Give an overview of the cmoon soft tissue knee injuries and their mechanisms for injury
- Valgus à MCL
- twisting à ACL or meniscal injury
- varus à LCL
- dashboard / hyperextension à PCL
- getting up from squatting à meniscal tear
Football injury, twist, pop, haemarthrosis, generalised pain, pain settles after a few days, rotatory instability.
What inury is this a classic histroy of ?
ACL rupture
Getting up from squatting, sudden sharp pain medial joint line, effusion, recurrent medial pain & catching +/- locking.
What injury is this a classic history of?
Meniscal tear
