Lecture 3 Flashcards
Rearfoot angle
- Angle between a line that bisects the distal 1/3 of the leg and a line that bisects the calcaneus
Patellofemoral joint
- Part of knee joint (patellofemoral and tibiofemoral)
- Posterior surface of patella and trochlear surface (groove) of femur
Posterior surface of patellofemoral joint
- Thick layer of hyaline cartilage up to 7mm
Trochlear sulcus (intercondylar groove)
- Distal femur forms inverted U-shaped patellar surface
- Extends further on lateral condyle
Patellofemoral articulation stability depends on
- Sufficient depth of trochlear sulcus
Soft tissue structures in patellofemoral articulation
- Medial and lateral retinacula
- Medial and lateral patellofemoral ligaments
- Medial and lateral patellotibial ligaments
- Iliotibial band
- Crural fascia
- Quadriceps aponeurosis
Dynamic stability of patellofemoral joint
- Muscles that stabilize the knee also stabilize the PFJ
- Quadriceps are important stabilizers of patella
- Pes anserine muscles
- Hamstring muscles
Quadriceps as important stabilizers of patella
- Vastus medialis obliquus
- Oblique portion of VM that attaches to medial patella
Chondromalacia Patella
- Degeneration of the articular cartilage of patella
- Caused by trauma and/or microtrauma
- Softening, erosion, fraying and fissuring
Cartilage loss can reach down to
- Subchondral bone
Typical chondromalacia patella representation
- Anterior knee pain that is aggravated by activities the increase patellofemoral contact
- Tenderness around patella borders
- Can have mild swelling
- Grinding sensation or crunching/crackling sound with squatting/stairs
Biomechanical abnormalities believed to contribute to chondromalacia patella
- Abnormal patellar tracking
- Q-angle
- Pes planus
- VMO to VL imbalance in strength or timing
- Weak hip abductors
- Femoral anteversion, tibial torsion, Genu valgum
- Trochlear dysplasia
- Patella alta
VMO to VL imbalance in strength or timing
VMO
- Inferior fibers of VM
- Have more horizontal orientation
- Important in patella stabilization and proper tracking
Q-angle
- Assess overall line of pull of the quadriceps relative to the patella
2 lines involved with Q-angle
- Line from the ASIS to the patella center (corresponds to force of quadriceps)
- Line from the patella center to the tibial tuberosity
Normal ranges of Q-angle
- Vary by source (~10-20ᵒ)
- Females: 15-18 > males: 10-13
Q-angle reflects
- Lateral pull of the quadriceps in relation to the patella
Increased Q-angle causes
- Excessive lateral tracking and lateral subluxation forces on patella
- Increases patellofemoral contact pressure, can cause pain, cartilage wear
Mechanical positions increasing Q-angle
- Femoral anteversion
- External tibial torsion
- Genu valgus
Mechanical axis
- A straight line connecting the center points of the proximal and distal joints
Mechanical axis of lower limb
- Center of femoral head to center of ankle
- Crosses center of knee joint
Changes in hip or knee alignment can alter the forces crossing neighboring joints
- Associated with the development and progression of osteoarthritis
- Advanced osteoarthritis can cause angular deformity
Normal angle of inclanation
- 125-135⁰ in adults
Coxa valga
- Angle of inclination > 135⁰ (some say 140⁰)
- Can cause genu varum (bow-legged)
- Can increase risk of knee osteoarthritis
Coxa vara
- Angle of inclination < 120⁰
- Can cause genu valgum (knocked knee)
- Can increase risk of knee osteoarthritis
Genu recurvatum
- Knee deformity where the knee angulates backwards
- Knee extension of > 5⁰ (past 0)
- Sagittal plane abnormality
Injuries that can cause genu recurvatum
- Tibia growth plate trauma
- Knee ligaments injury (ACL + posterior/lateral capsule)
Musculoskeletal abnormalities that can cause genu recurvatum
- Connective tissue disorders causing knee ligaments laxity
- Quadriceps muscle weakness
- Quadriceps spasticity
- Conditions that cause quad weakness or spasticity (CP, Muscular dystrophy, polio)
- Malformation of tibia (increased slope)
Patella alta
- Abnormally high patella
- Associated with patellofemoral pain and instability
- Chondromalacia patella and Knee OA
Causes of patella alta
- Rupture of patellar ligament
- Congenitally long patellar tendons
Patellar tendon (ligament) length
- > 1.2 patella alta
Patellar tendinitis (tendinopathy/tendinosis)
- “Jumper’s knee”
- Overload/overuse injury that is more common in sports involving repetitive jumping
- Higher load on patellar tendon/ligament during landing
Patellat tendon heals poorly (inadequate reapair)
- Thicker but collagen more disorganized
- Can eventually result in tenoncyte cell death and tendon degeneration
Patellar tendinitis most commonly involves
- Patellar ligament (patella to tibial tuberosity) at its patellar inferior pole attachment
- Pain at the inferior pole of patella
Iliotibial band syndrome
- Overuse injury that is caused by repetitive knee flexion and extension
- Typically see in cyclist and runner
IT band syndrome measurements
- At 0⁰ the band is anterior to the femoral epicondyle
- ~ 30⁰ it moves posterior
Causes of IT band syndrome
- Repetitive knee flexion/extension can create friction between lateral femoral epicondyle
Symptoms of IT band syndrome
- Presents with pain over lateral femoral condyle that can extend into lateral thigh/calf
- Can have snapping of ITB
