Soft Tissue Knee Injuries Flashcards
How may an extensor mechanism rupture occur?
Fall onto flexed knee with quadriceps contracted
What are risk factors for extensor mechanism ruptures?
Previous tendonitis, steroids, chronic renal failure, ciprofloxacin
What are the signs of an extensor mechanism rupture?
Unable to perform straight leg raise, palpable gap
What are the types of extensor mechanism ruptures?
Rectus femoris tear, quadriceps tendon rupture, patellar fracture, patellar tendon rupture = all need surgical repair
What are the function of the knee menisci?
Distribute load from convex femoral condyles to relatively flat tibial articular surfaces
What are some features of the lateral and medial menisci?
Medial = fixed, under greater amount of shear stress, medial plateau slightly more concave Lateral = more mobile
How does the knee move through flexion and extension?
Knee pivots on medial compartment = tibia internally rotates on flexion and externally rotates on extension
How do meniscal tears occur in younger patients?
Usually sporting injury or from getting up from a squatting position
How do meniscal tears occur in patients >40?
Atraumatic spontaneous degenerative tears
What other knee pathology are meniscal tears commonly associated with?
ACL ruptures = 50% have meniscal tear
On what aspect are meniscal tears more common?
Medial = 10 times more common than lateral meniscal tear
Why do meniscal tears have limited healing potential?
Only peripheral 1/3 has blood supply = radial tears will never heal
How is surgery used to treat meniscal tears?
Arthroscopic menisectomy = acute peripheral tears in younger patients, mechanical pain due to irreparable tears or failed meniscal repairs
Can meniscal tears resolve on their own?
To some extent = pain from the initial injury may settle over time
What does an acute locked knee signify?
Displaced bucket handle meniscal tear
What are some features of displaced bucket handle meniscal tears?
15 degree springy block to extension
Urgent surgery needed = if knee remains locked patient may develop FFD
How are displaced bucket handle meniscal tears treated?
Arthroscopic repair
Partial menisectomy for irreparable tear = unlocks knee and prevents further damage
What are some features of degenerative meniscal tears?
Occur in >20% of patients over 50, may be asymptomatic, inflammation from initial onset may settle, may represent first stage osteoarthritis
How are degenerative meniscal tears treated?
Injection may help, arthroscopic menisectomy ineffective, results form surgery less successful (especially if evidence of osteoarthritis)
What is the function of the MCL and the LCL?
MCL resists valgus stress = rupture may lead to valgus instability
LCL resists varus stress
What is the function of the ACL?
Resists anterior subluxation of tibia and internal rotation of tibia in extension = rupture may lead to rotational instability
What is the function of the PCL?
Resists posterior subluxation of tibia (i.e anterior subluxation of femur and hyperextension of knee)
What may occur if the PCL is ruptured?
Recurrent hyperextension or instability to descend stairs
What ligaments make up the posterolateral corner of the knee?
PCL, LCL, popliteus and other small ligaments = resist external rotation of tibia in flexion
What may occur in a rupture of the posterolateral corner?
Varus and rotary instability = multi-ligament injuries result in gross instability
What are the different grades of knee ligament injuries?
Grade 1 = sprain, tear some fibres but macroscopic structure intact
Grade 2 = partial tear, some fascicles disrupted
Grade 3 = complete tear
Do all ligaments heal at the same rate?
No = some heal more than others and some stabilise over time
What are some features of a MCL injury?
Usually heals well even if complete tear unless combined with ACL/LCL tear, pain can take several months to settle
How are MCL injuries treated?
Brace, early motion, physio, rarely requires surgery
What is the main stabiliser against internal rotation of the tibia?
ACL
What are ACL ruptures usually caused by?
Sports injury = football, rugby, skiing
How are ACL ruptures treated?
Only treated with reconstruction = autograft (hamstring or patellar tendon), allograft (Achilles)
ACL can stick to PCL to give some stability and physio can stabilise ACL deficient knees
How do patients cope with an ACL rupture?
1/3 compensate and are able to function well
1/3 can avoid instability by avoiding certain activities
1/3 don’t compensate and have frequent instability or can’t get back to high impact sport
Which patient group are more likely to compensate with an ACL rupture?
Older patients = also more likely to avoid high impact sport
When should surgery be considered for ACL ruptures?
Rotatory instability not responding to physio
Rapid return to professional sport/high demand job
Adolescent or young adult
Keen on high impact sport
As part of multi-ligament reconstruction
What are some drawbacks to surgery in an ACL rupture?
Doesn’t treat pain or prevent arthritis
How successful are ACL ligament reconstructions?
3 month to 1 year of rehab, some never get back to full sport, 10% failure rate, graft donor site morbidity, stiffness common, most have evidence of arthritis < 10 years
What are some features of LCL injuries?
Relatively uncommon, don’t heal well, cause varus and rotatory instability, high incidence in common peroneal nerve palsy, often occurs with PCL/ACL injury
How are LCL injuries treated?
Complete rupture needs urgent repair if early (within 2-3 weeks)
If >3 weeks then treated with reconstruction (hamstring or other tendon)
How do PCL rupture occur?
Direct blow to anterior tibia or hyperextension injury = often present with popliteal knee pain and bruising
Are isolated PCL ruptures common?
No, they are rare = usually occur with other injury
What can result from a PCL rupture?
Instability = recurrent hyperextension or feeling unstable when going downstairs
How are PCL ruptures treated?
Most isolated cases don’t require reconstruction = only gets reconstruction if part of multi-ligament injury
What are knee dislocations?
Serious high energy injury with high incidence of complications (popliteal artery injury, common peroneal nerve injury, compartment syndrome)
How are knee dislocations treated?
Emergency reduction
Vascular surgery may be needed
May need ex fix for temporary stabilisation
Multi-ligament
How can patellar dislocations arise?
Rapid turn or direct blow
What are some features of patellar dislocations?
Increased incidence in females, occurs in teens, ligamentous laxity, valgus knee, torsional abnormalities, 10% get recurrent dislocations
What can patellar dislocations cause?
Chondral or osteochondral injury = may benefit from surgical stabilisation
What are some mechanisms of injury?
Valgus = MCL Twisting = ACL, meniscal injury Varus = LCL Dashboard/hyperextension = PCL Getting up from squatting = meniscal tear
What does a pop or a crack of a joint indicate?
Knee cap dislocation
What are some causes of swelling?
Haemarthrosis = ACL, fracture Effusion = meniscal/chondral injury
What are some ways that pain can present?
Generalised haemarthrosis, joint line (meniscal/chondral injury)
What are some recurrent symptoms that can occur with knee injuries?
Giving way = rotary? Pain = joint line? Locking Clicking or catching Recurrent swelling or patellar dislocation
What are needed to diagnose osteoarthritis?
Biomarkers = not a uniform disease
What are some non-pharmacological treatments for osteoarthritis?
Strength training, weight management, walking cane, biomechanical interventions, Balneotherapy
What are some pharmacological treatments for osteoarthritis?
Capsaicin, paracetamol, topical NSAIDs, oral COX-2 inhibitors, duloxetine
When should surgery be given for osteoarthritis?
Only when conservative options have been exhausted, = may get knee replacement
What are some symptoms of osteoarthritis?
Pain, inflammatory flares, stiffness, loss of movement and function
