Biomecânica do Joelho: Ângulo q do Joelho

Summary

This educational video explores knee biomechanics, focusing on the quadriceps and patella tracking. It discusses the importance of the Q-angle, the role of muscle forces (lateralizing and medializing) on patellar movement, and factors contributing to abnormal tracking, such as genu valgum and femoral anteversion. The video explains how improper muscle function and structural imbalances, like tight internal rotators or a misaligned tibial tuberosity, can lead to patellar misalignment, increasing stress on the knee joint and causing pain. It emphasizes the need for targeted muscle strengthening and mechanical alignment to improve knee function and prevent injury.

Takeaways

• 😀 The quadriceps angle (Q-angle) is the angle formed between the patellar center, tibial tuberosity, and the anterior superior iliac spine.
• 😀 A larger Q-angle, often seen in women, increases lateral forces on the patella, potentially leading to patellar maltracking.
• 😀 Dynamic valgus (a condition where the knee moves inward) increases the Q-angle and thus the lateralizing forces on the patella.
• 😀 Both hip and foot control are critical in maintaining proper patellar alignment; weakness or misalignment in these areas can lead to knee problems.
• 😀 The Q-angle typically ranges from 11 to 16 degrees in men and 14 to 20 degrees in women due to differences in pelvic width.
• 😀 Increased Q-angle and dynamic valgus can be addressed through strengthening exercises targeting the gluteus medius and other hip muscles.
• 😀 Genovalgo (functional valgus deformity) results from tight medial rotators and weak lateral rotators, exacerbating patellar lateralization.
• 😀 Femoral anteversion (excessive forward rotation of the femur) can lead to internal rotation compensation and an increased Q-angle, contributing to patellar malalignment.
• 😀 Structural issues such as lateral tibial tuberosity position or excessive lateral retinacular tension can increase lateral forces on the patella, promoting maltracking.
• 😀 Strengthening external hip rotators (like the gluteus maximus, piriformis, and obturators) can help stabilize the hip joint and reduce patellar lateralization.
• 😀 In closed-chain activities, tibial external rotation with proper patellar tracking is crucial to avoid excessive lateralization and protect the patellofemoral joint.

Q & A

What is the Q-angle and why is it important in knee mechanics?

The Q-angle is the angle formed between the lines drawn from the center of the patella to the tibial tuberosity and from the center of the patella to the anterior superior iliac spine. It is important because it helps determine how the patella tracks during movement. A wider Q-angle can increase lateral forces on the patella, leading to potential misalignment or discomfort.

How does dynamic valgus affect the patella?

Dynamic valgus refers to the inward collapse of the knee during activities like running or jumping. This increases the Q-angle, leading to a greater lateral displacement of the patella. The lateral forces on the patella increase, which can cause patellar tracking issues and contribute to pain or injury.

What role do the quadriceps muscles play in patellar alignment?

The quadriceps muscles, particularly the vastus medialis and vastus lateralis, control the movement of the patella. The vastus medialis helps stabilize the patella medially, while the vastus lateralis can pull it laterally. Imbalances between these muscles can cause improper patellar alignment, leading to discomfort or injury.

What causes an increase in the Q-angle?

An increased Q-angle can be caused by factors such as wider pelvic structures, muscle imbalances (e.g., weak vastus medialis or tight vastus lateralis), knee valgus, or anatomical variations like femoral anteversion. These factors alter the alignment of the knee and increase lateral forces on the patella.

How does femoral anteversion affect the knee and patella?

Femoral anteversion refers to excessive internal rotation of the femur. This can increase the Q-angle, causing the patella to track laterally. The condition may also lead to knee valgus and pronation of the feet. Compensatory internal rotation of the femur helps improve joint congruence but also contributes to these mechanical issues.

Why is strengthening the hip external rotators important in managing patellar alignment?

Strengthening the hip external rotators is important because they help stabilize the femur and reduce internal rotation, which can exacerbate issues like femoral anteversion. This stabilization helps improve the Q-angle and decreases lateral forces on the patella, promoting better patellar tracking and reducing pain or risk of injury.

What is the significance of tibial alignment in knee mechanics?

Tibial alignment plays a crucial role in knee mechanics. If the tibia is misaligned (e.g., more lateral or internally rotated), it can affect patellar tracking. Proper tibial alignment ensures the patella moves smoothly within the femoral trochlea and helps avoid increased pressure on the patellofemoral joint.

What impact does tightness in the iliotibial band (ITB) have on the patella?

Tightness in the iliotibial band (ITB) can lead to lateral pulling on the patella, increasing the forces acting laterally. This can contribute to patellar maltracking and pain. ITB release or stretching can help reduce these lateral forces and improve patellar alignment.

How does muscle weakness in the vastus medialis affect patellar tracking?

Weakness in the vastus medialis, particularly in the last degrees of knee extension, can result in insufficient medial stabilization of the patella. This causes the patella to be pulled laterally by stronger lateral forces, increasing the risk of patellar misalignment and associated discomfort.

What are the common causes of patellar maltracking?

Patellar maltracking can be caused by several factors, including muscle imbalances (e.g., weak vastus medialis or tight vastus lateralis), anatomical variations (e.g., femoral anteversion, wide Q-angle), knee valgus, improper tibial alignment, and tightness in structures like the iliotibial band. These factors contribute to excessive lateral forces on the patella, leading to misalignment and potential pain.