Hip Anatomy Quiz

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Questions and Answers

What can happen if a patient with retroverted hips is instructed to bring their toes in for a squat?

Anterior impingement of the iliofemoral ligament (correct)

Reduced patellar tracking

Increased hip flexor strength

Greater range of motion in hip flexion

Which angle is indicative of anteversion in the hip?

Angle > 15°

Angle = 12°

Angle > 12° (correct)

Angle < 5°

What is the most common cause of snapping hip syndrome?

Labral tear

Tendon inflammation

Trochanteric bursitis

Muscle or tendon snapping over the bone (correct)

What palpation technique is used to reproduce symptoms in piriformis syndrome?

Deep palpation and piriformis stretch Signup and view all the answers

Which test is utilized to assess for acetabular labral tears during an exam?

FABER test Signup and view all the answers

What contributes to a high risk of a recurrent hamstring strain?

Inadequate warm-up activities Signup and view all the answers

What does Meralgia Paresthetica result from?

Entrapment near the ASIS Signup and view all the answers

What is the recommended initial treatment for strains?

Assessing the muscle before any stretching Signup and view all the answers

Which of the following is a potential presentation of an acetabular labral tear?

Groin pain with joint clicking Signup and view all the answers

Which condition is characterized by buttocks pain radiating down the leg due to sciatic nerve compression?

Piriformis syndrome Signup and view all the answers

Which structure is NOT part of the osseous components of the hip?

Fibula Signup and view all the answers

What is the most common direction of hip dislocation?

Posterior and superior Signup and view all the answers

What primarily prevents the posterior tilt of the pelvis when standing erect?

Iliofemoral ligament Signup and view all the answers

Which trabecular pattern runs from the femoral head to the trochanteric area?

Tension trabeculae Signup and view all the answers

What component covers the center of the acetabulum?

Fatty tissue coated by synovial membrane Signup and view all the answers

As individuals age, the likelihood of which type of fracture increases?

Trochanteric-femoral neck fractures Signup and view all the answers

Which ligament limits the extension of the hip joint?

Iliofemoral ligament Signup and view all the answers

Which statement is true about the femoral head?

It is covered by hyaline cartilage except for fovea capitis. Signup and view all the answers

Which ligament lies anterior and superior, forming an inverted Y shape?

Iliofemoral ligament Signup and view all the answers

What type of biomechanical evaluation is emphasized as most important?

Biomechanics and evaluations Signup and view all the answers

What is the primary function of the pubofemoral ligament?

Limits external rotation and extension Signup and view all the answers

In which position is the hip joint in the closed-packed position?

Full extension, internal rotation, and abduction Signup and view all the answers

What is the angle of inclination for a normal femoral neck-shaft?

~125 degrees Signup and view all the answers

Which muscle group provides posterior stability to the hip joint?

Hamstrings and gluteus maximus Signup and view all the answers

What is a primary role of the ligamentum teres?

Protects the nutrient artery supplying the femoral head Signup and view all the answers

What is one potential effect of coxa valga on a person?

Longer leg with toes in Signup and view all the answers

Which bursa is located between the iliopsoas and hip joint capsule?

Iliopectineal bursa Signup and view all the answers

How does the transverse ligament function in the hip joint?

Converts the acetabular notch into a foramen Signup and view all the answers

What can cause inflammation in the trochanteric bursa?

Direct trauma or overuse Signup and view all the answers

Which muscles contribute to medial stability of the hip joint?

Pectineus and gracilis Signup and view all the answers

Match the following hip ligament with its function:

Iliofemoral ligament = Prevents posterior tilt of pelvis when standing erect Ischiofemoral ligament = Limits extension of hip joint Pubofemoral ligament = Prevents excessive abduction Ligamentum teres = Provides blood supply to the femoral head Signup and view all the answers

Match the following osseous structures with their descriptions:

Ilium = Superior part of the innominate bone Ischium = Posteroinferior part of the innominate bone Pubic = Anteroinferior part of the innominate bone Acetabulum = Socket for the femoral head Signup and view all the answers

Match the following types of trabecular patterns with their characteristics:

Tension trabeculae = Run from femoral head to trochanteric area Compression trabeculae = Run from trochanteric area to femoral head Cortical bone = Provides strength and support Trabecular network = Aids in load distribution Signup and view all the answers

Match the following components with their locations:

Femoral head = Covered by hyaline cartilage except for fovea capitis Trochanteric area = Where tension trabeculae are more superior Acetabular labrum = Peripheral surface of the acetabulum Femoral neck = Most susceptible to fractures with age Signup and view all the answers

Match the following statements with the correct descriptions:

Hip dislocation = Most commonly occurs in posterior & superior direction Capsular ligaments = Wrap around the acetabular labrum Hyaline cartilage = Covers the femoral head except for the fovea capitis Fatty tissue in acetabulum = Covered by synovial membrane Signup and view all the answers

What occurs during the eccentric contraction of a muscle?

Muscle lengthens while maintaining tension Signup and view all the answers

What is the approximate Q angle range in females due to pelvic shape?

10-15 degrees Signup and view all the answers

Which injury mechanism is most likely to result in an MCL injury?

Valgus blow with a flexed knee Signup and view all the answers

What happens to the fibula during ankle plantarflexion?

Fibula lowers and rotates externally Signup and view all the answers

What is a consequence of an ACL injury stemming from forced internal rotation of the femur on a fixed tibia?

Increased risk of meniscus tears Signup and view all the answers

Which position of the patella indicates patella alta?

Patella is higher than the tibial tuberosity Signup and view all the answers

What action does the medial femoral condyle primarily check during knee movement?

Posterior displacement and internal rotation of the tibia Signup and view all the answers

Which ligament becomes taut specifically during knee extension, abduction, and external rotation?

Medial collateral ligament (MCL) Signup and view all the answers

What is the main shape characteristic of the medial meniscus?

Semilunar shape Signup and view all the answers

Which muscle group is primarily involved in knee flexion and internal rotation during open-chain exercises?

Hamstring muscles Signup and view all the answers

What is the primary function of the pes anserinus tendons?

Prevent external rotation, abduction, and anterior displacement of the tibia Signup and view all the answers

Which knee structure serves as a shock absorber and is made of fibrocartilage?

Menisci Signup and view all the answers

What common injury mechanism is associated with the medial collateral ligament (MCL)?

ACL injury Signup and view all the answers

Which bursa is located above the patella?

Suprapatellar bursa Signup and view all the answers

What physiological angle does the femoral shaft produce in alignment with the lower leg?

170-175 degrees Signup and view all the answers

Where is the ACL primarily attached on the tibia?

Anterior part Signup and view all the answers

Which ligament is most commonly injured in the triad injury involving the knee?

Anterior cruciate ligament (ACL) Signup and view all the answers

What does the PCL primarily prevent regarding tibial movement?

Posterior displacement Signup and view all the answers

In what state are knee ligaments most susceptible to injury?

When taut Signup and view all the answers

What unique characteristic does the patella have in the human body?

It is the largest sesamoid bone Signup and view all the answers

Which bursa is most likely to become inflamed during prolonged kneeling?

Infrapatellar bursa Signup and view all the answers

What mechanism occurs when the tibia externally rotates under the femur during knee extension?

Screw-home mechanism Signup and view all the answers

Which muscle group is primarily responsible for knee flexion?

Hamstrings Signup and view all the answers

What is the primary role of the menisci in the knee joint?

Shock absorption Signup and view all the answers

During which phase does the tibia internally rotate?

Swing phase Signup and view all the answers

Which statement best describes the shape of the lateral meniscus?

Almost a full circle and larger than medial meniscus Signup and view all the answers

What occurs during knee extension in a closed-chain position?

The femur internally rotates Signup and view all the answers

What is an effect on stress in a joint if the area is increased?

Decreased stress Signup and view all the answers

Which part of the knee contains the most proprioceptors?

Lateral meniscus Signup and view all the answers

What action do the quadriceps primarily perform at the knee joint?

Extension Signup and view all the answers

Match the following structures with their characteristics:

Femur = Produces a physiological valgus angle of approximately 170-175° Patella = Largest sesamoid bone in the body ACL = Checks anterior displacement and extension of the tibia PCL = Strongest ligament of the knee Signup and view all the answers

Match the following ligaments with their specific functions:

ACL = Becomes taut in knee flexion MCL = Connected to the medial meniscus PCL = Attached from the posterior part of the tibia Lateral Collateral Ligament = Stabilizes against varus stress Signup and view all the answers

Match the following knee-related terms with their definitions:

Injury triad = ACL + MCL + medial meniscus injuries Innervation = Knee joint innervated by L3-S1 nerve roots Physiological valgus angle = Angle created by the alignment of the femur and lower leg Medial femoral condyle = More inferior to the lateral femoral condyle in lateral view Signup and view all the answers

Match the following descriptions with the correct knee ligament locations:

ACL = Attached from the anterior part of the tibia, moving to the lateral femoral condyle PCL = Attached from the posterior part of the tibia, moving to the medial femoral condyle MCL = Runs along the inner knee from femur to tibia Lateral Collateral Ligament = Runs along the outer knee from femur to fibula Signup and view all the answers

Match the following anatomical features with their functions:

Meniscus = Acts as a shock absorber and is made of fibrocartilage Patella = Aids in lever mechanics of the knee joint Ligaments = Provide stability by connecting bone to bone Articular Cartilage = Cushions joints and reduces friction Signup and view all the answers

Study Notes

Hip Anatomy

Osseous Structures:
- Innominate: Made up of three bones: ilium (superior), ischium (posteroinferior), and pubic (anteroinferior).
- Acetabulum: Faces anterior, lateral, and inferior. Center of the acetabulum contains fatty tissue covered by the synovial membrane.
- Hip Dislocation: Most common direction is posterior & superior, unlike the shoulder joint. Differences occur due to muscle, ligaments, and open/closed-packed positions.
- Femoral Head: Covered by hyaline cartilage except for the fovea capitis. It faces posterior, medial, and superior.
- Trabecular Patterns: Tension trabeculae run superiorly from the femoral head to the trochanteric area, while compression trabeculae run inferiorly from the trochanteric area to the femoral head. As we age, the likelihood of trochanteric-femoral neck fractures increases.
Capsular Ligaments:
- Wrap around and extend from the peripheral surface of the acetabular labrum to the intertrochanteric line.
- Thicker on the anterosuperior portion of the capsule.
- Iliofemoral Ligament: Lies anterior & superior, extending from the AIIS to the trochanteric line of the femur. Forms an inverted Y, preventing posterior tilt of the pelvis when standing erect, and limits hip extension.
- Ischiofemoral Ligament: Lies posterior & inferior, extending from the ischium to the inner surface of the greater trochanter. Reinforces the posterior capsule, limiting internal rotation, abduction, and extension.
- Pubofemoral Ligament: Extends from the obturator crest & superior ramus of the pubis to the deep vertical bands of the iliofemoral ligament. Reinforces the medioinferior joint capsule, limiting external rotation, abduction, and extension.
- Ligamentum Teres: Extends from the fovea capitis femoris to each side of the acetabular notch. Provides some protection for the nutrient artery supplying the femoral head and becomes taut when the thigh is semiflexed and adducted or externally rotated. It can assist with lubrication of the femoral head.
- Transverse Ligament: Crosses the acetabular notch. Converts the notch into a foramen, which the nutrient artery that supplies the femoral head crosses.
Musculature:
- Stabilities:
  - Posterior: Gluteus maximus, posterior fibers of Gluteus medius, Hamstrings, Piriformis.
  - Anterior: Iliopsoas, Sartorius, Quadriceps/rectus femoris muscles.
  - Lateral: TFL, Gluteus medius, Gluteus minimus.
  - Medial: Pectineus, Adductor muscles, Gracilis.
- Bursae:
  - Iliopectineal Bursa: Located between the iliopsoas and the hip joint capsule. Excess fluid can spill into it due to trauma. Hip flexion and adduction or excessive extension can compress the inflamed bursa.
  - Trochanteric Bursa: Located between the gluteus maximus tendon and IT band and the greater trochanter. Direct trauma or overuse can inflame the bursa.
  - Ischiogluteal Bursa: Located superficially over the ischial tuberosity. Prolonged sitting can cause inflammation.

Hip Biomechanics

Closed-Packed Position: Full extension, internal rotation, and abduction.
Loose-Packed Position: ~30 degrees of flexion, ~30 degrees of abduction, and slight external rotation.
Degree of Movements:
- Flexion: 120-130 degrees
- Extension: 10-15 degrees
- Abduction: 40-45 degrees
- Adduction: 30-35 degrees
- Internal Rotation: 30 degrees
- External Rotation: 45 degrees
Femoral Neck:
- Angle of Inclination (Neck-Shaft): ~125 degrees (normal range 90-135 degrees).
 - Coxa Valga: Angle > 125 degrees. Greater pressure on the femoral head. Longer leg with toes in. Differential Diagnosis: immobilizing disorders and cerebral palsy .
 - Coxa Vara: Angle < 125 degrees. Greater pressure on the femoral neck. Shorter leg with toes out. Differential Diagnosis: skeletal dysplasia, fractures, AVN, SCFE, Rickets, Paget's disease.
- Angle of Anteversion (Neck-Femoral Condyles): ~12 degrees (normal range 10-30 degrees).
 - Anteversion: Angle > 12 degrees. Produces toe-in posture.
 - Retroversion: Angle < 12 degrees. Produces toe-out posture.
- Note: This is different from genu valgum and varum, which relate to the knee. Coxa valga is an increased angle of inclination of the femoral neck to the shaft, while genu valgum/valgus is a decreased angle of the femoral shaft to the tibial shaft, causing knees that are bowed inward.

Hip Exam Considerations

Bursitis:
- Iliopectineal Bursa: Pain with hip flexion & adduction
- Trochanteric Bursa: Pain with hip abduction and external rotation
- Ischiogluteal Bursa: Pain with prolonged sitting.
- Tenderness Over Bursa: Differentiate from OA, lumbar radiculopathy, IT band syndrome, and muscle strain.
- Treatment: Primarily rest. Work surrounding tissues to reduce pressure on the bursa. Adjustments to the lower back and pelvis.
Snapping Hip:
- Background: A muscle or tendon snapping over bone.
  - External: Most common. IT band, glutes, TFL
  - Internal: Iliopsoas
  - Intra-articular: Labral tears, fracture fragments, loose bodies.
- Presentation: Repeatable audible/palpable click or snap.
- Provocative: Movements involving muscles.
  - Hip Abduction: Iliopsoas (pain more anterior)
  - Hip Adduction: IT band, TFL, glutes (pain more lateral)
- Exam:
  - Psoas: Going from hip flexion to extension and external rotation.
  - TFL/IT band: Side lying going from hip internal rotation to external rotation.
- DDx: Bursitis, OA, tendinopathy, labral tear.
- Treatment: Address muscle tightness/weakness through muscle work and adjustments.
Piriformis Syndrome:
- Background: Compressed/irritated sciatic nerve from the piriformis muscle.
- Presentation: Buttocks pain that can radiate down the leg. Potential antalgic gait with externally rotated hip on the affected side. Tenderness over glutes/piriformis.
- Provocative: Sitting, hard surfaces, anything that involves internally rotating the hip (due to a tight piriformis muscle).
- Exam: Deep palpation and piriformis stretch reproduces symptoms. Lumbar ROM is normal.
- DDx: Lumbar radiculopathy, SI joint syndrome, hamstring strain.
- Treatment: Heat/stretching, manual massage. Improve internal and external hip rotator strength and flexibility .
Acetabular Labral Tear:
- Presentation: Groin pain most common. Potential lower back/glute referral. Joint clicking and locking. Usually normal ROM.
- Provocative: Activities, deep hip flexion. "Hip giving way."
- Exam:
  - Impingement Test: Pt in supine, hip flexion, slight adduction, and gentle internal rotation (stresses the anterior labrum).
  - FABER: Pt in Figure 4 position, hip abduction and external rotation (stresses the posterior labrum).
  - MRI: Gold standard for diagnosis.
- DDx: DJD, groin strain, hernia
- Treatment:
  - Outer Labral Tears: (outer 1/3rd) Respond well to conservative treatment: heat/stretching, manual massage, strengthen surrounding muscles.
  - Inner Labral Tears: (inner 2/3rd) May require surgery.
Strains:
- Groin (Adductors): Most commonly adductor longus. Forceful abduction leads to pain in the adductors as they try to restrict the abduction. Pain worsens with abduction.
- Hamstrings: Stretched eccentrically at high speeds (quick stops, changing directions). Weak glutes, adductors, and core muscles lead to increased hamstring activation. Patients should not return to activity until 90% strength is restored (a 75% chance of recurrent strain if rehab is not completed). Pain worsens with hip flexion.
- Both: Caused by overstretching or inadequate warm-up. Sudden ripping, stabbing, or popping sensation in the muscle.
  - Acute: Do not stretch, needs to be assessed.
  - Grade 3 Tear: Full rupture, less pain, but more muscle weakness.
  - Recovery: Passive ROM, eventually isometric contractions.

Nerves of The Hip

Femoral Nerve: Trauma, dislocation, or hematoma can cause entrapment. Presents with anterior thigh numbness.
Sciatic Nerve: Can be compressed by the piriformis muscle or due to canal stenosis. Presents with motor and sensory changes.
Lateral Femoral Cutaneous Nerve: Entrapment near the ASIS where the nerve passes laterally through the inguinal ligament. Creates Meralgia Paresthetica (burning pain sensation in the anterolateral thigh). Standing up is palliative.

Hip Anatomy

Osseous Structures:
- Innominate: Consists of ilium (superior), ischium (posteroinferior), and pubis (anteroinferior).
- Acetabulum: Faces anterior, lateral, and inferior. The center of the acetabulum contains fatty tissue covered by synovial membrane.
- Hip Dislocation: Most common direction is posterior and superior, unlike the shoulder where it's anterior and inferior. This difference is due to musculature, ligaments, and open/closed-packed positions.
- Femoral Head: Covered by hyaline cartilage except for the fovea capitis, which faces posterior, medial, and superior.
- Trabecular Patterns:
  - Tension Trabeculae: Run superiorly from the femoral head to the trochanteric area.
  - Compression Trabeculae: Run inferiorly from the trochanteric area to the femoral head.
  - As we age, the likelihood of trochanteric - femoral neck fractures increases.
Capsular Ligaments:
- Wrap around and extend from the peripheral surface of the acetabular labrum to the intertrochanteric line.
- The capsule is thicker on the anterosuperior portion.
- Iliofemoral Ligament:
  - Lies anterior and superior.
  - Extends from AIIS to the trochanteric line of the femur, forming an inverted Y.
  - Prevents posterior tilt of the pelvis when standing erect.
  - Limits hip joint extension.
- Ischiofemoral Ligament:
  - Lies posterior and inferior.
  - Extends from the ischium posteriorly to the inner surface of the greater trochanter.
  - Reinforces the posterior capsule.
  - Limits internal rotation, abduction, and extension.
- Pubofemoral Ligament:
  - Extends from the obturator crest and superior ramus of the pubis to the deep vertical bands of the iliofemoral ligament.
  - Reinforces the medioinferior joint capsule.
  - Limits external rotation, abduction, and extension.
- Ligamentum Teres:
  - Extends from the fovea capitis femoris to each side of the acetabular notch.
  - Provides some protection to the nutrient artery supplying the femoral head.
  - Becomes taut when the thigh is semiflexed and adducted or externally rotated.
  - Lined with synovium and can assist with lubrication of the femoral head, acting like a meniscus.
- Transverse Ligament:
  - Crosses the acetabular notch.
  - Converts the notch into a foramen, allowing the nutrient artery to cross.
Musculature:
- Stabilities:
  - Posterior: Gluteus maximus, posterior fibers of Gluteus medius, Hamstrings, Piriformis.
  - Anterior: Iliopsoas, Sartorius, Quadriceps/rectus femoris muscles.
  - Lateral: TFL, Gluteus medius, Gluteus minimus.
  - Medial: Pectineus, Adductor muscles, Gracilis.
- Bursae:
  - Iliopectineal Bursa:
    - Located between the iliopsoas and hip joint capsule.
    - Trauma can cause excess fluid to spill into it.
    - Hip flexion & adduction, or excessive extension can compress the inflamed bursa.
  - Trochanteric Bursa:
    - Separates the gluteus maximus tendon & IT band from the greater trochanter.
    - Direct trauma or overuse can inflame the bursa.
  - Ischiogluteal Bursa:
    - Superficial over the ischial tuberosity.
    - Prolonged sitting can inflame the bursa.

Hip Biomechanics

Closed-Packed Position: Full extension, internal rotation, and abduction.
Loose-Packed Position: 30 degrees of flexion, 30 degrees of abduction, and slight external rotation.
Femoral Neck:
- Angle of Inclination (Neck-Shaft): ~125o; 90-135o.
 - Coxa Valga: Angle > 125o. Greater pressure on the femoral head. Longer leg with toes in.
 - Coxa Vara: Angle < 125o. Greater pressure on the femoral neck. Shorter leg with toes out.
 - Note: This is different from genu valgum and varum, which relate to the knee. Coxa valga represents an increased angle of inclination between the femoral neck and shaft.
- Angle of Anteversion (Neck-Femoral Condyles): ~12o; 10-30o (also known as angle of torsion).
 - Larger in children and decreases with age.
 - Note: The femoral head stays put in the acetabulum. The distal portion (tibia) will either compensate by externally rotating or staying in place and internally rotating.
 - Anteversion: Angle > 12o. Produces toe-in posture.
 - Retroversion: Angle < 12o. Produces toe-out posture.

Hip Conditions

Bursitis:
- Pain and tenderness over the affected bursa.
- Types: Trochanteric, iliopectineal, and ischiogluteal.
- Provocative Factors:
  - Trochanteric: Direct trauma, overuse.
  - Iliopectineal: Hip flexion & adduction, excessive extension.
  - Ischiogluteal: Prolonged sitting.
- Treatment: Rest, work surrounding tissues, avoid pressure on bursa, adjustments to the lower back and pelvis.
Snapping Hip:
- Description: A muscle or tendon snapping over a bony prominence.
- Types:
  - External: Most common. IT band, glutes, TFL.
  - Internal: Iliopsoas.
  - Intra-Articular: Labral tears, fracture fragments, loose bodies.
- Presentation: Repeatable audible/palpable click or snap.
- Provocative Factors: Movements involving the involved muscles.
  - Psoas: Hip flexion to extension & external rotation (anterior pain).
  - TFL/IT band: Side-lying, hip internal rotation to external rotation (lateral pain).
- Treatment: Muscle work (address muscle tightness/weakness), adjustments.
Piriformis Syndrome:
- Description: Compressed or irritated sciatic nerve by the piriformis muscle.
- Presentation: Buttocks pain radiating down the leg, potential antalgic gait with external hip rotation on the affected side, tenderness over glutes/piriformis.
- Provocative Factors: Sitting, hard surfaces, activities involving internal hip rotation.
- Treatment: Heat/stretching, manual massage, work on internal & external rotators.
Acetabular Labral Tear:
- Presentation: Groin pain, potential lower back/glute radiation, joint clicking & locking, usually normal ROM.
- Provocative Factors: Activities, deep hip flexion, "hip giving way."
- Diagnosis: MRI is the gold standard.
- Treatment:
  - Outer labral tears (outer 1/3) typically respond to conservative treatment (heat, stretching, manual massage, strengthening).
  - Inner labral tears (inner 2/3) may require surgery.
Strains:
- Groin (Adductors):
  - Most commonly adductor longus.
  - Forceful abduction leads to pain as adductors try to restrict movement.
  - Pain worsens with abduction.
- Hamstrings:
  - Stretched eccentrically at high speeds (quick stops, changing direction).
  - Weak glutes, adductors, and core lead to increased hamstring activation.
  - Pain worsens with hip flexion.
- General:
  - Causes: Overstretching or lack of warm-up.
  - Symptoms: Sudden ripping, stabbing, popping sensation.
  - Recovery: Passive ROM, gradual isometric contractions.
Nerve Entrapment:
- Femoral Nerve: Trauma, dislocation, hematoma can cause entrapment. Anterior thigh numbness.
- Sciatic Nerve: Can be compressed by the piriformis muscle or due to spinal stenosis. Presents with concurrent motor and sensory changes in the nerve distribution.
- Lateral Femoral Cutaneous Nerve: Entrapment near the ASIS where the nerve passes lateral to the inguinal ligament. Causes meralgia paresthetica (burning pain) in the anterolateral thigh. Standing up often provides relief.

Knee Anatomy

Innervation: L3-S1 nerve roots innervate the knee joint
Femur: Femoral shaft is angled, creating a valgus angle of 170-175 degrees
Patella: Largest sesamoid bone in the body
Ligaments: Injuries most common when ligaments are taut
- ACL:
  - Attaches from the anterior tibia to the lateral intercondylar wall of the femur
  - Prevents anterior tibial displacement and extension
  - Most commonly injured ligament
  - Taut in knee flexion
- PCL:
  - Attaches from the posterior tibia to the medial intercondylar wall of the femur
  - Prevents posterior tibial displacement and internal rotation
  - Strongest knee ligament
  - Provides medial to lateral stability in knee extension
  - Taut in knee extension
- MCL:
  - Attaches from the medial tibia to the medial femoral epicondyle
  - Prevents knee extension, abduction, and external rotation
  - Also checks some anterior tibial displacement
  - Taut in knee extension, abduction, and external rotation
  - Common injury during ACL injuries due to shared actions
- LCL:
  - Attaches from the fibular head to the lateral femoral epicondyle
  - Popliteus tendon runs between the LCL and bony surfaces
  - Prevents knee extension, adduction, and external rotation
  - Taut in knee extension, adduction, and external rotation
Menisci: Shock absorbers made of fibrocartilage, crucial for knee stability and function
- Medial Meniscus: Semilunar shape, larger on the outside, wrapping around the medial femoral condyle; posterior portion larger than anterior, tolerating more weight in knee flexion
- Lateral Meniscus: Almost full circle shape
Muscles:
- Hamstrings: From medial to lateral: Semimembranosus, Semitendinosus, Biceps Femoris long and short head
- Plantaris: Flexes and internally rotates in open-chain movements
- Pes Anserineus: Tendon insertion site on the medial tibia
  - Composed of the semitendinosus, gracilis, and sartorius tendons
  - Prevents external rotation, abduction, and anterior tibial displacement
Bursa: Reduce friction between tendons, muscles, and ligaments
- Suprapatellar Bursa: Above the patella
- Prepatellar Bursa: In front of the patella, superficial to the patellar ligament; can become inflamed from prolonged kneeling
- Infrapatellar Bursa: Below the patella, superficial to the patellar ligament
- Baker's Cyst: Posterior aspect of the knee at the medial head of gastrocnemius

Knee Biomechanics

Knee Joint Functions:
- Reacts to rotational forces
- Absorbs shock
- Propulsion
Extension: Primarily performed by the quadriceps
Flexion: Performed by the hamstrings, gracilis, and sartorius
Tibiofemoral Joint:
- Primarily a hinge joint with slight rotation allowed when not in the closed-packed position
- Screw-Home Mechanism:
  - Open-chain: As knee extends, the tibia externally rotates under the femur
  - Closed-chain: As knee extends, the femur internally rotates over the tibia
- Absorption:
  - Menisci: Shock absorbers, increase surface area and joint stability
  - Shock: Stress = force/area; increasing area reduces stress
- Pain: Menisci have mechanoreceptors and proprioceptors; lateral meniscus has most proprioceptors, making injuries there very painful
- Propulsion: Important for gait, particularly in hemiplegic patients
  - Muscular Component:
    - Eccentric: Muscle lengthens under tension
    - Concentric: Muscle shortens under tension
Patellofemoral Joint:
- Patella sinks during knee flexion, increasing force output
- Q Angle:
  - Line from the center of the patella to the ASIS
  - Approximately 10-15 degrees
  - Slightly higher in females due to pelvic shape
- Patellar Position:
  - Alta: high
  - Baja: low
Superior Tibiofibular Joint:
- Influenced by ankle joint movements:
  - Dorsiflexion: Fibula internally rotates and rises
  - Plantarflexion: Fibula externally rotates and lowers
  - Inversion: Fibular head moves anteriorly
  - Eversion: Fibular head moves posteriorly

Knee Evaluation

General Information: Knee trauma common, hip and ankle must be assessed as well, referred pain from LBP can affect the knee.
Collateral Ligament Injuries:
- MCL:
  - MOI: External rotation twisting with flexed knee, valgus blow (lateral to medial)
  - Increased likelihood of medial meniscus and ACL injuries
- LCL:
  - MOI: Internal rotation twisting with hyperextension, varus blow (medial to lateral)
  - Can cause fibular head avulsion
ACL Injuries:
- MOI:
  - Forced internal rotation of femur on fixed tibia with abduction/flexion
  - Knee hyperextension with valgus stress (hard landing)
  - Sudden eccentric quadriceps contraction
- Symptoms: Loud pop, rapid and aggressive swelling
- Management: Surgery dependent on severity, age, and activity level, MRI, stabilization program for hamstrings and proprioceptive training
PCL Injuries:
- MOI:
  - Forced external rotation of femur on fixed tibia with abduction/flexion
  - Impact on a flexed tibia (car accident)
- Symptoms: Loud pop, swelling develops quickly, may have increased bruising
- Management: Similar to ACL, but surgery less commonly required, stabilization program for quadriceps and proprioceptive training.
Meniscus Injuries:
- MOI: Rotation with violent extension, potential for compression
- Symptoms: Knee locking in flexion, knee "giving way," swelling
- Management:
  - Stable tears: Rest and proper intervention
  - Unstable tears: Require surgery to prevent further tearing
- Protected weight-bearing and protective ROM training
Patellofemoral Issues:
- Patellar Tracking: Relationship between vastus medialis and lateralis
- Can lead to accelerated osteoarthritis and chondromalacia patella
- Chondromalacia Patella: Erosion of the posterior cartilage of the patella
  - Causes: Improper patellar tracking, increased Q angle, infrapatellar bursa inflammation
  - Management: Bracing, taping, muscle strengthening
- Patellar Tendinitis: Anterior knee pain with explosive movements
  - Causes: Repetitive stress to the patellar tendon
  - Management: Rest, isometric holds of knee extension

Knee Anatomy

Innervation: Knee joint is innervated by L3-S1 nerve roots.
Femur: Femoral shaft is obliquely aligned with the lower leg, creating a physiological valgus angle (approximately 170-175 degrees).
Medial femoral condyle: Located more inferiorly than the lateral femoral condyle on a lateral view.
Patella: Largest sesamoid bone in the body.

Knee Ligaments

Ligament Injuries: Most common when ligaments are in their most taut state.
Injury Triad: ACL, MCL, and medial meniscus are commonly injured together due to their location and actions.
ACL:
- Location: Connects from the anterior tibia to the posterior and superior lateral intercondylar wall of the femur.
- Action: Checks anterior displacement and extension of the tibia.
- Injury: Most commonly injured ligament, becomes taut in knee flexion.
PCL:
- Location: Connects from the posterior tibia to the anterior and superior medial intercondylar wall of the femur.
- Action: Checks posterior displacement and internal rotation of the tibia.
- Injury: Strongest knee ligament, becomes taut in knee extension.
MCL:
- Location: Connects the proximal medial tibia to the medial side of the medial femoral epicondyle.
- Action: Checks knee extension, abduction, and external rotation.
- Injury: Becomes taut in knee extension, abduction, and external rotation. Commonly injured with ACL injuries.
LCL:
- Location: Connects the proximal fibular head to the lateral side of the lateral femoral epicondyle. The popliteus tendon runs between the LCL and the bony surfaces.
- Action: Checks knee extension, adduction, and external rotation.
- Injury: Becomes taut in knee extension, adduction, and external rotation.

Knee Menisci

Function: Shock absorbers, made of fibrocartilage, lubricated for nourishment.
Medial Meniscus: Semilunar shape. The outer part is larger, wrapping around the medial side of the medial femoral condyle. The posterior part is larger than the anterior and can withstand more weight with knee flexion.
Lateral Meniscus: Almost full circle shape.

Knee Muscles

Hamstring Muscles: Semimembranosus (deep), semitendinosus (superficial), biceps femoris long head, biceps femoris short head (medial to lateral).
Plantaris: Can only flex and internally rotate in open-chain exercises due to its size.
Pes Anserinus Tendons: Common insertion site for tendons on the medial tibia.
- Components: Semitendinosus, gracilis, and sartorius tendons.
- Function: Helps prevent external rotation, abduction, and anterior displacement of the tibia. The semimembranosus tendon also contributes to this function, but not part of the pes anserinus group.

Knee Bursae

Function: Help prevent friction by separating tendons from ligaments and muscles.
Suprapatellar Bursa: Located above the patella.
Prepatellar Bursa: Located in front of the patella, superficial to the patellar ligament. Can become inflamed from prolonged kneeling.
Infrapatellar Bursa: Located below the patella, superficial to the patellar ligament.
Baker's Cyst: Located on the posterior aspect of the knee, near the medial head of the gastrocnemius at its origin.

Knee Biomechanics

Key Actions: Rotational forces, shock absorption, propulsion.
Extension: Quadriceps muscles.
Flexion: Hamstrings, gracilis, and sartorius muscles.
Tibiofemoral (Knee) Joint:
- Rotation Forces: Mostly a hinge joint. There is slight rotation when the knee is not in a closed-packed position.
- Screw-Home Mechanism:
  - Open-Chain (fixed femur): As the knee extends, the tibia externally rotates under the femur.
  - Closed-Chain (fixed tibia): As the knee extends, the femur internally rotates over the tibia.
- Absorption:
  - Congruency (Menisci):
    - Shape: Medial meniscus (semilunar, smaller than lateral), Lateral meniscus (almost full circle, larger than medial). Thicker on the periphery.
    - Function: Shock absorption, increased surface area, increased stability.
  - Shock: Stress = Force / Area
    - Increased Area = Less Stress
    - Decreased Force = Less Stress
- Pain: Menisci have mechanoreceptors and proprioceptors.
  - Mechanoreceptors: Help orient the knee in space.
  - Proprioceptors: Most concentrated in the lateral parts of the menisci, making tears in this area very painful.
- Propulsion: Important for gait, especially with hemiplegia.
  - Muscular Components:
    - Eccentric: Muscle lengthens under tension (contracting, but weight overpowering causing lengthening).
    - Concentric: Muscle shortens under tension (able to perform a bicep curl).

Patellofemoral Joint

Knee Flexion: Patella sinks down to the tibial tuberosity, lengthening the lever arm and increasing force output.
Q-Angle: Line drawn from the center of the patella to the shaft of the femur up to the ASIS (anterior superior iliac spine).
- Normal: ~10-15 degrees
- Females: Slightly larger due to pelvic shape.
Patellar Position:
- Alta: High
- Baja: Low

Superior Tibiofibular Joint

Ankle Joint Influence: Primarily influenced by the ankle joint.
Dorsiflexion: Fibula internally rotates and rises.
Plantarflexion: Fibula externally rotates and lowers.
Inversion: Fibular head moves anterior.
Eversion: Fibular head moves posterior.

Knee Evaluation

Common Injury: Trauma is frequent in the knee.
Assessment: When assessing the knee, also assess the hip and ankle.
Referred Pain: Lower back pain can cause some discomfort in the knee.

Collateral Ligament Injuries

Cause: Usually due to trauma.
MCL Injury:
- MOI: External rotation twisting with a flexed knee, Valgus blow (lateral to medial).
- High Likelihood: Associated with medial meniscus injury, as well as ACL injury.
LCL Injury:
- MOI: Internal rotation twisting with hyperextension, Varus blow (medial to lateral).
- Possible Outcome: Can cause fibular head avulsion due to LCL connection.

ACL Injury

MOI:
- Forced internal rotation of the femur on a fixed tibia with knee abduction and flexion (e.g., cutting in football or soccer).
- Knee hyperextension with valgus stress (e.g., hard landing with a firmly planted foot).
- Sudden eccentric quadriceps contraction (e.g., sudden stop from a sprint causing anterior tibia "pull" relative to the femur).
Symptoms: Loud pop, rapid and aggressive swelling.
Management: Surgery depends on severity, age, and activity level. MRI, stabilization program (hamstrings, proprioceptive training).

PCL Injury

MOI:
- Forced external rotation of the femur on a fixed tibia with knee abduction and flexion (similar to ACL).
- Impact mechanisms (e.g., impact on a flexed tibia driving the tibia posterior relative to the femur).
Symptoms: Loud pop, rapid swelling (less than ACL, but may include increased bruising).
Management: Similar to ACL, but surgery is less common. Stabilization program (quadriceps, proprioceptive training).

Meniscus Injuries

MOI: Rotation with violent extension, potentially some compression.
Symptoms: Difficulty locking the knee in a flexed position, knee "giving way", swelling.
Management:
- Stable Tears: Don't require surgery, can heal with rest and proper intervention.
- Unstable Tears: Without intervention will lead to further tearing and greater issues.
- Protected Weight-Bearing: Protective ROM training.

Patellofemoral Issues

Patellar Tracking: Related to the relationship between the vastus medialis and lateralis muscles.
Potential Outcomes: May contribute to premature osteoarthritis or chondromalacia patella.
Chondromalacia Patella: Erosion of the posterior cartilage of the patella.
- Causes: Constant grinding of posterior cartilage due to improper tracking, increased Q angle, inflammation of the infrapatellar bursa.
- Management: Bracing, taping, strengthening.

Patellar Tendinitis

Symptoms: Anterior knee pain with explosive movements.
Causes: Repetitive stress on the tendon.
Management: Rest, isometric holds of knee extension.

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Test your knowledge on the anatomy of the hip, including its osseous structures, ligaments, and common injuries. This quiz covers essential topics such as the innominate bones, acetabulum, and femoral head characteristics. Perfect for students and professionals in anatomy and physical therapy.