Knäextension

Knäextension refers to the movement that straightens the knee joint, moving the leg from a flexed position toward full extension. The primary muscles responsible for knee extension are the quadriceps (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius), which act across the knee joint to straighten the leg. The movement is influenced by the patellofemoral mechanism and knee ligaments, and is stabilized by surrounding soft tissues during activity.

Biomechanics and range of motion: In a healthy adult, knee extension is considered full at 0 degrees, with flexion typically ranging up to about 135–140 degrees. During walking and running, the knee passes through extension phases that contribute to stance stability and propulsion. The alignment of the patella and the integrity of the extensor mechanism affect the efficiency and control of extension.

Clinical significance: Adequate knee extension is essential for standing, walking, and many daily activities. A limitation in extension, known as an extension deficit or lag, can impair gait and may result from swelling, pain, muscle inhibition, scar tissue, or mechanical issues such as meniscal tears. Hyperextension, or genu recurvatum, occurs in some individuals and can place different stresses on knee structures.

Rehabilitation and training: Restoring and maintaining full knee extension is a common rehabilitation priority after injury or surgery. Early focus often includes quadriceps activation and gentle range of motion to reduce swelling, followed by progressive strengthening and ROM exercises. Open- and closed-chain exercises, proprioceptive training, and gait rehabilitation are used as tolerated. In sport and strength training, proper technique and gradual progression help protect the extensor mechanism and patellofemoral joint.