Knee Flashcards
Why is normal 10 deg Valgus at the knee present?
- Medial Femoral Condyle Extends longer distally than does the Lateral Femoral Condyle
Why does the Lateral Femoral Condyle Extend Longer Anteriorly than the Medial Femoral Condyle?
- Prevent Lateral Translation of the Patella
What structures are the Lateral and Medial Meniscus attached to in order to allow for Posterior Translation during knee flexion?
- Lateral- Popliteus
- Medial- Semimembranosus
In what knee position are the MCL and LCL Taut?
- Extension
In what knee position are the bundles of the ACL Taut?
- Post-Lat Bundle- Extension
- Ant-Med Bundle- Flexion
What are the important stabilizing structures of the Posterolateral Corner?
- Lateral Collateral Ligament
- Popliteus Tendon
- Popliteofibular Ligament
Describe Hughstons Tests for knee Ligamentous Laxity
- Similar to Post Drawer, but with Tibia in ER or IR approx 15 deg
- ER tests Posterolateral Corner
- IR tests Posteromedial instability
Describe Slocums Tests for Knee Ligamentous Laxity
Similar to Ant Drawer, but with Tibia in IR or ER approx 15 deg
- IR tests Anterolateral Instability
- ER tests Anteromedial Instability
What are common Tests used to diagnose Posterolateral Corner Injury?
- Dial Test
- Hughstons Test (Posterolateral Drawer)
- Varus Stress Test
- External Rotation Recurvatum Test
Disruption of the Infrapatellar Bursa may cause what type of patellofemoral abnormality?
- Patella Baja
What is a lateral blowout sign of the knee?
- Swelling over the Lateral Joint Line following an injury
- Occurs because the capsule is very thin on the lateral side of the knee
What is the role of the Posterior Oblique Ligament of the knee?
- Primary Ligamentous Structure on the Posterior Medial side of the knee
- Controls Anterior Medial Rotary Instability
- Provides static resistance against Valgus when the knee moves into full extension
What is the role of the arcuate complex?
- Comprised of the LCL, Arcuate Ligament, and popliteus
- Controls Internal Rotation of the Femur on the Tibia during closed chain activity
What bony factors can result in lateral tracking of the patella?
- Dysplastic Patella
- Patella Alta
- Shallow Intercondylar Groove
What Soft tissue factors can result in lateral tracking of the patella?
- Tight Lateral Retinaculum
- Tight IT Band
What is Patella Alta?
- Cephalad position of the Patella
What is Lateral Pressure Syndrome?
- Caused by tight lateral retinaculum tightness ,pulling the patella laterally
What is the difference between Osgood Schlatters and Sinding Larsen Johannson?
- Both are Apophysitis
- Osgood Schlatter is of the Tibial Tubercle
- Synding Larsen Johannson is of the distal pole of the patella
What is Hoffas Fat Pad Disease?
- Pain and swelling of the infrapatellar fat pad
- Usually from trauma to anterior knee
- TTP Medial and Lateral Joint Lines
What is Housemaids Knee?
- Prepatellar Bursitis
- Usually in pnts who work while kneeling
- Repetitive blunt trauma to Anterior Knees
What is the typical MOI of Patellar Dislocation?
- External Rotation of Tibia Combined with Valgus stress the knee
What are Contraindications for meniscal surgery?
- Tears that do not heal well with or without surgery as below
- Tears > 3 cm
- Transverse Tears
- Tears with secondary lesions that extend into the avascular portion
What is a Fibrin Clot?
- Placed at the meniscal injury to form a wound hematoma and encourage healing
What is a Meniscal Cyst?
- Ganglion Like Formations secondary to central degeneration of the meniscus
- Occur more often in lateral meniscus
What is a diskoid meniscus?
- Congenital deformity of the shape of the meniscus
- May abnormally affect the contact force through the meniscus
What is a Segund Fracture?
- Avulsion of the Anterolateral Margin of the lateral tibial plateau
- Associated with ACL tears
At what range of motion is the ACL Stressed the most in the open chain?
- During Knee Extension from 45-20 deg with most stress at 20
- Virtually no stress on ACL in full extension
What amount of Quadriceps Strength is required to return to activity after ACL repair?
- 50% for jogging
- 65% for sports agility
- 80% for full return to sports
With Medial Knee instability in a 10 year old after a valgus injury, what might be the cause?
- Suspect Epiphyseal Plate Injury
- MCL is stronger than the Physes in youth and instability can be other than ligamentous in this population
What are some commonly associated injuries of Distal Femoral Fracture?
- Peroneal Nerve Palsy
- Ipsilateral Hip Fracture or Dislocation
- Vascular Injury
- Damage to Quadriceps
What are primary restraints to Valgus Stress?
- MCL is primary
- PCL plays supportive role
What are the bundlles of the ACL and in what positions are they most taut?
- Posterlateral Bundle, Taut in Extension
- Anteromedial bundle, Taut Throughout Flexion
Describe the bundles of the PCL
- Anterolateral Bundle- Large, 95% of PCL, Taut in Flexion
- Posteromedial Bundle- Small, 5%, Taut in Extension
- Anterolateral the priority during reconstruction
What are common MOI’s for Isolated PCL Injury?
- Hyperflexion
- Direct Posterior Translation of Tibia such as a dashboard injury (often resullts in injuries to secondary restraints)
How does the KOOS Functional Outcome Measure differ from the WOMAC
- KOOS more responsive to those of higher activity level
- WOMAC designed to assess patients with OsteoArthritis of the Knee
How do you perform Fluid Wave Grading of Knee Effusion?
- Swelling pushed up the medial knee distally to proximally
- Then sweep the hand back down toward lateral knee and watches for swelling
- Graded Trace, 1+, 2+, 3+
What structures might be implicated with Valgus Stress testing at different degrees of knee flexion?
- At Full Extension- if opening > 5 mm, PCL and ACL may be involved
- At 30 Deg Flexion- if opening > 10 mm, ACL may be involved
What structures might be implicated with Varus Stress testing at different degrees of knee flexion?
- In Full Extension- LCL, ACL, and PCL may be involved
- 30 deg Flexion- Primarily LCL
What is the Posterolateral Corner Comprised of?
- Arcuate Ligament
- LCL
- Popliteal Tendon
- Lateral Head of Gastrocnemius
What are the 5 measures of the Meniscal Pathology Composite Score?
- History of Catching or Locking
- Joint Line Tenderness
- Pain with forced Hyperextension
- Pain with Maximal Passive Flexion
- Pain or Audble click with McMurray
What is a “Sage Sign”?
- Greater than 25-50% displacement of patellar width of the patella with lateral and medial passive movement
- Indicative of Laxity of supporting tethers
Describe a Patellar Apprehension Test
- in 20-30 deg of knee flexion, the patella in manually subluxed
- Excessive movement and patient expressions of concern are positive and indicative of excessive laxity or history of subluxations
Describe the Patellar Tilt Test
- Tests flexibility of Lateral Retinaculum
- Knee at 20 deg flexion, attempt to tilt the lateral edge up, normal just above horizontal but with tight retinaculum, no movement
What is the role of Patellar Movement during Knee Flexion and Extension?
- During Flexion, patella glides inferiorly
- During Extension, patella glides superiorly
What is the purpose of a NotchPlasty?
- Allows for increased space in the Joint
- Prevents roof and lateral wall impingement
What are the most common procedures for patella realignment?
- HIgh Tibial Osteotomies
- Fulkerson, Hauser, Elmslie Trillat
