Knee Joint Biomechanics Quiz

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Questions and Answers

What is the normal Q-angle for females when the knee is straight?

13°

10°

15°

18° (correct)

Which factors are known to increase the Q-angle?

Increased patellar tendon length and reduced retinaculum tension

Genu valgum and external tibial torsion (correct)

Tight quadriceps tendon and medially located tuberosity

Genu varum and decreased anteversion

What maintains the normal alignment of the patella inferiorly?

Vastus lateralis

Patellar tendon (correct)

Iliotibial band

Quadriceps tendon

At what degree of knee flexion does the patella occupy its greatest contact area with the trochlear groove?

Between 90 to 60 degrees Signup and view all the answers

Which condition may lead to an inaccurate Q-angle measurement in knee extension?

Laterally dislocated patella Signup and view all the answers

What is considered a key element to knee stability for standing upright?

Screw home rotation Signup and view all the answers

What is the role of the popliteus muscle during knee unlocking from full extension?

To internally rotate the femur Signup and view all the answers

What is the resting position of the patellofemoral joint?

Full extension Signup and view all the answers

In the context of knee joint biomechanics, what does the Q angle represent?

The alignment of the patella Signup and view all the answers

Which of the following positions is known as the closed packed position for the tibiofemoral joint?

Full extension with external rotation Signup and view all the answers

Which anatomical structure is NOT involved in the locking mechanism of the knee?

Patellar tendon Signup and view all the answers

What limits the amount of flexion more than extension in both the tibiofemoral and patellofemoral joints?

The orientation of the femoral condyles Signup and view all the answers

What is the angle formed by the center of the femoral shaft to the center of the knee joint known as?

Anatomical axis Signup and view all the answers

What indicates that the patient may be experiencing transient inhibition of the quadriceps?

Pain or deconditioning Signup and view all the answers

Which of the following aggravates anterior knee pain according to the symptoms listed?

Climbing stairs and jogging Signup and view all the answers

What condition could indicate hypermobility of the patella during examination?

Translation of more than three quadrants medially Signup and view all the answers

What symptom often occurs due to irritation of the infra patellar fat pad?

Localized tenderness at the patellar attachment Signup and view all the answers

Which test evaluates lateral instability when pain or discomfort occurs?

Lateral translation test Signup and view all the answers

What can contribute to irritation of the IT band as it passes over the lateral femoral condyle?

Tight tensor fasciae latae Signup and view all the answers

What indicates a positive outcome in the evaluation of the patella grasp test?

Pain during medial translation Signup and view all the answers

What is the primary factor contributing to 'housemaid’s knee'?

Recurrent minor trauma to the anterior knee Signup and view all the answers

At what degree range of knee flexion is the greatest patellar stress experienced?

60 - 75 degrees Signup and view all the answers

What anatomical position describes a patella that is higher than normal?

Patella Alta Signup and view all the answers

What occurs to the patella's position as the knee extends?

It rises from the inter-condylar groove. Signup and view all the answers

Which factor contributes significantly to increased quadriceps muscle torque when the knee is flexed?

Increase in the length of its moment arm. Signup and view all the answers

What type of patella is described as facing laterally and upward?

Frog Eye Patella Signup and view all the answers

Which statement correctly describes patellofemoral contact forces during knee extension?

They decrease as the knee extends. Signup and view all the answers

In which range of knee flexion do patellar fat pads or synovial tissue irritation generally cause pain?

0 - 15 degrees Signup and view all the answers

How much vertical movement of the patella occurs in the intercondylar groove during knee flexion and extension?

8 cm Signup and view all the answers

What is the primary definition of patellar maltracking?

Mal-alignment of forces around the patella during knee motion Signup and view all the answers

Which of the following factors is NOT associated with patellar tracking disorders?

Osteoarthritis of the knee joint Signup and view all the answers

What effect does a laterally displaced tibial tuberosity have on the knee?

It can lead to increased lateral tracking of the patella. Signup and view all the answers

Which of the following conditions may lead to an increased Q angle?

Weakness of the hip external rotators Signup and view all the answers

Which muscle weakness is primarily linked to the condition of patellar maltracking?

Vastus medialis obliqus Signup and view all the answers

What symptom might a patient with patellar maltracking commonly report?

Knee giving way Signup and view all the answers

Which of the following is least likely to be a direct consequence of an increased Q angle?

Improved patellar tracking Signup and view all the answers

Which biomechanical change is commonly associated with patellar maltracking?

Tight quadriceps Signup and view all the answers

What is a common consequence of inflammation in the patellar region?

Restricted motion due to swelling and pain Signup and view all the answers

What does patellar pain indicate?

It represents pathological changes in the articular cartilage Signup and view all the answers

Which condition is characterized as traction apophysitis of the tibial tuberosity?

Osgood-Schlatter's disease Signup and view all the answers

Which of the following activities should be avoided to manage patellar issues?

Squatting Signup and view all the answers

Which exercise is recommended for strengthening the vastus medialis muscle?

Quadriceps strengthening exercises Signup and view all the answers

What is the main goal of performing medial glide techniques?

To reduce tightness of the iliotibial band Signup and view all the answers

What contributes to the displacement of the patella in individuals with flat foot?

Foot pronation Signup and view all the answers

Which of the following strategies is NOT recommended for injury prevention?

Using worn-out shoes Signup and view all the answers

Study Notes

Runner's Knee (PFPS)

Objectives: Students will be able to review knee joint anatomy, recognize anterior knee pain syndrome, identify its causes, and plan appropriate rehabilitation.

Knee Joint Anatomy

Bones: Tibia, Femur, and Patella
Articulations: Tibiofemoral and Patellofemoral
Ligaments: MCL, LCL, ACL, and PCL
Menisci: Medial and Lateral menisci
Articular Cartilage: Covers joint surfaces

Knee Joint Alignment

Femoral Mechanical Axis: Center of the femoral head to the center of the knee.
Femoral Anatomical Axis: Center of the femoral shaft to the center of the knee joint. It deviates 6° outward from the mechanical axis.
Genu Valgum (Knock-Knee): Excessive valgus alignment of the knee, potentially resulting in a Q-angle larger than normal.
Genu Varum (Bowleg): Characterized by a bowed appearance of the legs, with the knees aligned in varus.

Screw-Home Mechanism

Rotation: Knee rotates approximately 5-10 degrees during the last phase of extension.
Mechanism Differences: Rotation during knee extension is different than general axial rotation at the knee. It is a coupled rotation, linked mechanically to flexion and extension.
Factors: Shape of femoral condyles, passive tension in the anterior cruciate ligament, and lateral pull from the quadriceps tendon.

Knee Joint Positions

Closed Packed Position: Full extension and external tibial rotation (tibiofemoral joint). Full knee flexion (patellofemoral joint).
Resting Position: 25° of flexion (tibiofemoral joint). Full extension (patellofemoral joint).
Capsular Position: Flexion more limited than extension (both joints).

Patellar Tracking

Path & Area: Patellar contact on the femur varies during knee flexion and extension. At 135° of flexion, the patella rests on the medial & lateral facets. At 90° of flexion, it rests on the superior pole. Between 90° to 60° flexion, the patella occupies the greatest contact area with the trochlear groove (30% of total surface area). In full extension, it rests above the intercondylar groove, against the supra-patellar fat pads.
Normal Alignment: Maintained by iliotibial band & lateral retinaculum laterally, vastus medialis medially, patellar tendon inferiorly, and quadriceps tendon superiorly.
**Natural Bowstringing Force:**The lateral traction forces on the patella are caused by the iliotibial band, lateral patellar retinacular fibers, and overall quadriceps force. Medial directed forces include the vastus medialis and medial patellar retinacular fibers.
Abnormal Positions: Frog-eye, squinting, rotated inward/outward, patella alta, patella baja.
Stress: Maximum stress on the patella occurs during 60-75° of flexion

Special Tests

Patellar Gliding: Assessing patellar translation in the resting position. Measure displacement in quadrants. Less than one quadrant indicates tightness of lateral structures. More than three quadrants indicates hypermobility
Patellar Apprehension: Evaluating for lateral instability. Positive test = lateral translation produces pain or discomfort.
Patellar Tilting: Measuring the patellar tilt relative to the axis.
Patellar Grinding: Investigating for pain or crepitus during patellar glide.

Patellofemoral Pain Syndrome (PFPS)

Definition: Anterior knee pain, diffuse, dull, and aching. It results from changes in the patellofemoral joint, outside of any other medical pathology.
Epidemiology: Common in runners, young athletes, basketball players, and bicyclists, especially women.

Causes of PFPS

Overuse: Repetitive movements, especially with increases in activity levels
Trauma: Knee injury or impacts
Abnormal Forces: Abnormal biomechanics may initiate a cascade of issues.
Muscle Imbalance (Weakness or Tightness): Imbalance between thigh muscles, tight hamstrings, tight quadriceps, weak vastus medialis oblique (VMO)
Patellar Tracking Disorders: Including patella alta, patella baja, iliotibial band issues and femoral anteversion issues
Foot Issues: Pronated feet, pes cavus/flat foot issues
Excess Weight: Increased stress on the knee joint

History of PFPS

Location: Specific area of knee pain
Aggravating Activities: Activities that provoke pain
Associated Symptoms: Giving way, swelling, catching/popping/grinding sensations, stiffness

Physical Examination

Standing Exam: Assess lower extremity alignment, focusing on femoral position when feet are together.
Dynamic Exam: Evaluating knee response during walking, stair climbing, and squatting.
Special Tests: Patellar gliding, apprehension, tilting, and grinding tests to identify tightness of lateral structures.

Treatment

Rest: Reduce activity levels associated with pain.
Strengthening: Quadriceps (especially VMO), hip adductors, hamstrings, gastrocnemius, and hip external rotators.
Stretching: Hamstrings, gastrocnemius, ITB, and quadriceps.
Taping: Patellar taping
Proprioception Training: Improved body awareness and balance
Myofascial Release: Addressing tightness of the Iliotibial band (ITB).
Foot Orthotics: If foot pronation contributing to knee pain

Prevention

Stay in Shape: Maintain appropriate fitness level.
Stretching: Before & after exercise
Gradual Training Increase: Avoid sudden increases in activity levels.
Proper Running Gear: Use supportive shoes and other gear (as appropriate).
Proper Running Form: Correct running mechanics.

Differential Diagnosis

Fat Pad Syndrome: Irritation of infra-patellar fat pad from overuse or trauma.
Quadriceps Tendonitis: Overuse or repeated jumping.
IT Band Friction Syndrome: Irritation of the IT band over the lateral femoral condyle, often associated with tightness of tensor fasciae latae (TFT).
Prepatellar Bursitis: Repeated kneeling, or minor trauma.
Chondromalacia Patellae: Cartilage damage due to abnormal stress to the patella.
Patellofemoral Osteoarthritis: Radiographic changes associated with degereration.
Osgood-Schlatter Disease: Inflammation of the tibial tubercle, especially in adolescents.

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Description

Test your knowledge on knee joint biomechanics with this quiz. Explore questions regarding the Q-angle, patellar alignment, and the anatomical intricacies that contribute to knee stability and flexion. From the roles of key muscles to the mechanics of locking, assess your understanding of the human knee.