Knee Flashcards
Normal genu valgum
- Slight medial angulation of the femur, horizontal tibial articular surface
- Knee forms an angle on the lateral side of 170-175 (5-10 degrees of genu valgum)
Excessive genu valgum
15 degrees)
Genu varum
> 180 degrees in frontal plane
Three compartments of the knee
- Medial compartment (medial tibial plateau, meniscus, femoral condyle)
- Lateral compartment
- Patellofemoral compartment
^ Used to describe OA and TKA/ partial KA
Mismatch of surfaces of femur and tibia
Large convex femoral condyle
Smaller tibial plateaus
Meniscus function
“Gaskets” to improve joint congruity and stability
Shock absorption –> disperse load on articular cartilage to a wider surface area
Meniscus injury increases OA risk
Deform in weight bearing
Mobile: Move with the tibia. Lateral moves more than medial (more tears occur in medial)
Medial vs. lateral tibial plateau
Medial: Concave
Lateral: Mostly flat (Slightly concave)
Femoral condyles - medial vs. lateral
Lateral condyle is steeper
Femoral groove is aka trochlea
Thickest hyaline cartilage in the body?
Patella
Makeup of menisci
Fibrocartilage (like labrum, IVD)
- Large water content
Anchored in the intercondylar area
Coronary ligaments
Vascular and nerve supply to menisci
- Inner 2/3 poorly vascularized, not innervated
- Outer 1/3: Vascular, innervated
Medial meniscus
- C shaped
- Less mobile than lateral
- Attachments: Joint capsule, MCL, ACL at anterior horn, Semimembranosus at posterior horn
Attaches to MCL via menisco-tibial/ coronary ligaments
- Body’s center of mass usually runs through medial compartment –> more tears
- Varus malalignment is more common with degeneration (increases medial stress) –> more tears
Lateral meniscus
- O shaped
- More mobile (weaker capsular attachments)
- No attachment to LCL
- Attachments: PCL, Popliteus, medial mensicus (via transverse ligament in anterior knee)
Tears in lateral are less common than tears in medial
Meniscal Tear special tests
Thessaly
McMurray
Apley
Palpation for tenderness (more posterior than you think, along jt line)
None of these tests are great
Thessaly test
For meniscus tear
- Pt stands on one leg
- Pt flexes knee to 20 degrees, rotates body over knee
- Repeat rotation 3 time in each direction
Positive: Joint-line pain and possibly a sense of locking or catching
McMurray’s Test
For meniscus tear
- Pt in supine
- Grasp heel and flex knee to EROM, using other hand to palpate jt line
- Medial meniscus: ER tibia as knee is extended
- Lateral meniscus: IR tibia as knee is extended
Positive: Audible or palpable thud or click
Apley’s Test
For meniscus tear
- Pt in prone
- Knee flexed to 90 degrees
- Load menisci and twist (this is part 2 of test)
Part 1: distraction of tibia and twist
Swelling inside joint capsule
Effusion
Joint capsule and reinforcing ligaments
Anterior: Major contribution from medial and lateral patellar retinaculum
Posterior: Reinforced by oblique popliteal ligament and the arcuate popliteal ligament
Lateral: LCL, ITB, lateral patellar retinaculum, biceps, popliteal tendon
Medial: Patellar tendon to posterior capsule. MCL, medial patellar retinaculum
Posterior-medial capsule reinforces by pes
Synovial lining of capsule
- Provides nourishment and lubrication to joint
- Highly vascular and innervated
- Lines capsule, except it wraps around cruciate ligaments and excludes them
–> Cruciates are intracapsular but extrasynovial