Which statement about the knee is incorrect?
Several bursae aid in the movement of the knee.
The deep cups created by the tibial articular surfaces help to stabilize the joint.
Several ligaments cross the knee to stabilize the knee in several directions.
The knee is vulnerable to lateral forces that can cause injury.
The correct answer and explanation is:
The incorrect statement is:
“The deep cups created by the tibial articular surfaces help to stabilize the joint.”
Explanation:
The knee is a hinge joint composed of the femur, tibia, and patella. Unlike the hip joint, which has a deep socket (acetabulum) that securely holds the femoral head, the tibial articular surfaces are relatively shallow. This lack of deep bony stability in the knee makes it heavily reliant on soft tissues—ligaments, tendons, and muscles—for stability and proper function. Here’s a detailed breakdown of why this statement is incorrect and the significance of the other options:
- Bursae aid in knee movement:
The knee contains several bursae—fluid-filled sacs—that reduce friction and facilitate smooth movement between structures such as bones, tendons, and skin. Examples include the suprapatellar bursa, prepatellar bursa, and infrapatellar bursa. - Ligaments stabilize the knee:
Several important ligaments cross the knee joint to provide stability. These include the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL). Each ligament prevents excessive movement in specific directions, protecting the joint from injury. - The knee’s vulnerability to lateral forces:
The knee is particularly susceptible to injuries from lateral or rotational forces. For example, a blow to the outside of the knee can cause damage to the MCL, ACL, or menisci. Sports involving sudden direction changes, jumping, or contact increase this risk. - Tibial articular surface is not deeply cupped:
The tibial plateau is relatively flat, which does not inherently stabilize the joint. Stability is instead provided by the menisci (fibrocartilaginous structures that deepen the joint surface slightly), ligaments, and muscles like the quadriceps and hamstrings. This makes the knee joint biomechanically complex but also prone to injury without proper support.