Knee Flashcards
Which meniscus is more mobile?
The lateral meniscus
What kind of cartilage makes of the menisci?
Fibrocartilage
Which section of the meniscus is the least likely to heal?
The white-white or innermost
What history or MOI makes you think meniscus?
-Twisting
-Worse with movement, better with rest
-“locking”
-Joint line tenderness
-Effusion within 2 hours
-Sudden onset in those <40 years old, no specific MOI in those >50
Will all meniscal tears have “locking?”
No, some can just “shake it out” and keep going
What are the types of meniscal tear?
-Longitudinal
-Bucket-Handle (progressed longitudinal)
-Radial (perpindicular to curve)
-Root
-Oblique/flap
-Horizontal
Who has a good meniscal healing prognosis?
-Age <35
-Peripheral damage
-Longitudinal tear
-Short tear
-Acute injury with bloody effusion
-Stable knee
What are hallmark meniscal objective findings?
-Joint line tenderness
-Effusion
-Postive entrapment test (McMurray’s, Apley’s, Squat)
-Quad Inhibition (atrophy over first 1-2 weeks post injury)
What is joint line tenderness good for regarding meniscal injury?
Good Sensitivity (ruling out if negative)
What is the timeline for return to activity with meniscal debridement/meniscectomy?
1-2 weeks for ADLs, longer for athletic endeavors
At what length of meniscal tear is a meniscal repair indicated?
Longer than 8 mm
What are the indications for a meniscal repair?
-Traumatic lesion in the vascular zone
-Intact peripheral circumferential fibers
-Minimal damage to the meniscal body
-Longer than 8 mm
Arthroscopic partial meniscectomy and physical therapy are both..what?
likely to result in considerable improvement in functional status and knee pain over a 6-12 month period
Why avoid early hamstring strengthening after meniscal repair?
The semimembranosus connects to the medial meniscus
What kind of cartilage does articular cartilage consist of?
Hyaline cartilage - to reduce friction between the ends of bones
What type of articular cartilage lesions are symptomatic?
Grade III, IV; Grade I and II are typically asymptomatic
What can be said about image findings and articular cartilcage pathophysiology?
There is a poor correlation
What are some signs of articular cartilage damage?
-Resting genu varus
-Painful crepitus
-Catching, locking, grinding
-Sensitivity to weather changes
-Too little and too much activity is painful
-Quad atrophy
-Deep, dull ache
What are the options for surgical management of knee issues from more palliative to restorative?
-Debridement and lavage
-Microfracture
-Autologous Chondrocyte Implantation
-Osteochondral Grafting (OATS)
What is being done with articular catilcage debridement and lavage?
Removal of cartilage particles and inflammatory cells for short term pain relief of symptoms
What does the research say regarding debridement and lavage for articular cartilage lesions?
-No improvement compared to sham
-Little or no difference in pain or ability to function
-Maybe better than washout
Describe microfracture as a treatment for articular cartilage lesions.
Making pick holes through tidemark to encourage blood flow; replaces cartilage with fibrocartilage
What does the research say regarding medium to long-term outcomes with microfracture for articular cartilage lesions?
Poor regaring getting back to sport, better with sedentary or low post operative demand individuals. Treatment failure after 5 years is expected
Describe the Autologous Chondrocyte Implantation (ACI) procedure
Small biopsy of autologous articular cartilage harvested, enzymatically digested in a lab to release chondrocytes, which are cultured and then implanted at a second surgery with a periosteal flap placed as a patch
When is an osteochondral autograft transplantation system indicated?
With full-thickness articular cartilage defects
Describe the osteochondral autograft transplantation system procedure
Remove plug from NWB surface then press-fit the plugs implanted into the lesion
What are the best surgical options for large articular cartilage lesions?
Autologous Chondrocyte Implantation or Osteochondral Autograft Transplantation System
What is considered a “large” articular cartilage defect?
> 4 cm
What is a key factor in determining how to intervene with articular cartilage defects?
Low or high demand postoperatively
When is microfracture not recommended?
Lesions >4 cm and for those with high postoperative demands
What are principles of articular cartilage rehab?
-Understand the surgical procedure
-Control WB Status
-PROM is key
-Slow and progressive rehab
-Rarely return to sports: think ADLs
-Need communication with MDs
What are functional subunits (bundles) of ligaments?
Ligaments are packaged into bundles, which different bundles are more tense than others at different joint angles; work together to provide stability in specific directions.
Ligaments have elastic and viscous properties, what is the difference?
Elastic properties deform in proportion to the load and assume the original shame when removed; Viscous properties dampen forces and are time/duratin and rate/speed dependent
On what conditions do mechanical properties of ligaments vary?
Temperature, injury, disease, aging
What changes with ligaments during healing?
They initially heal with scar tissue that is predominantly Type III collagen with less tensile strength, more randomly oriented with more hydrogen cross-link bonds.
Scar tissue will contract possibly reducing joint motion
Why is mechanical stress needed during healing?
Moderate stress induces organization of collagen into more parallel arrangement, resulting in more covalent cross link formation, minimizing scar contraction.
What is sufficient stress for mechanical deformation during healing of a ligament?
Joint movement
What happens to a ligament with immobilization?
-Ligament atrophy
-Reduction in intracellular matrix and inferior ligament material production
-Resorption of bony insertion sites
-Reduced tensile strength
-Adaptive shortening of structures
-Changes in uninjured structures
-Starts in just a few weeks from immobilization
-50% of mechanical strength lost aftger 6-9 weeks of immobilization
How long does it take for ligament substance to recover after immobilization?
Months
What MCL injuries involve the meniscus?
Grade II and III
What is known about the MCL bundles?
There are multiple and restrain motion at different angles
Is the meniscus attached to the LCL?
No, it is separated by the popliteus
At what point of knee flexion is the LCL most effective as a restraint?
From 0-30 degrees
What movement does the ACL restrain?
Anterior translation of the tibia on femur or posterior translation of the femur on tibia
Which ACL bundle is most taut in flexion?
Anterior-medial bundle
Which ACL bundle is most taught in extension?
The posterior lateral bundle
What happens to the ACL bundles as the knee flexes?
The bundles twist
Which bundle of the PCL is most taught in flexion?
Anterior-lateral
Which bundle of the PCL is most taught with extension?
Posterior-medial bundle
What motion does the PCL restrain?
Posterior tibial translation or anterior femoral translation;
Secondary: femoral external rotation and tibial internal rotation
The ACL assists in sliding the femoral condyles anteriorly when?
During knee flexion
The PCL assists in sliding the femoral condyles posteriorly when?
During knee extension
What are signs of collateral ligament injury?
-Varus or valgus trauma
-Pos varus or valgus stretss testing
-Swelling, Ecchymosis
-Joint effusoin if meniscal involvement
-TTP at ligament
-Difficulty with pivoting, cutting, etc. (“can run in a straight line but feel like my knee will fall apart if I turn quickly)
What are signs and symptoms of ACL injury?
-Severe pain with joint effusion
-“popping” “giving way” “buckling”
-Continued effusion, giving way
-Quad inhibition
-Limited ROM
-Flexed knee gait
What are ACL mechnisms of injury?
-NC: fixed foot with knee in valgus/rotational load
-NC: Hyperextension load (stepping in pothole)
-C: Posteriorly directed blow to anterior femur
-C: Blow to lateral knee with planted foot
How common are non-contact vs contact injuries of the ACL?
Non-contact 80%
Contact 20%
Which ACL test hits more of teh posterior bundle?
Lachman’s
Which ACL tests more of the anteror bundle?
Anterior Drawer Test
What are signs and symptoms of PCL injury?
-Posterior knee pain
-Effusion, less than ACL
-Flexion beyond 90 increasing pain
-Difficutly descending stairs, squatting, running
-+sag sign
-+posterior drawer
-reduced palpation of tibial plateau step-off
What is the mechanism of PCL injury?
-Hyperflexion
-Fall on a flexed knee with foot in plantarflexion
-Hyperextension
-Step in a pot hole
-Blow in anterior tibia (dashboard)
