Which muscle is primarily affected by hip flexor contracture?

The iliopsoas muscle is primarily affected by hip flexor contracture because it is one of the main muscles responsible for hip flexion. The iliopsoas consists of two muscles: the psoas major and the iliacus. When a hip flexor contracture occurs, the iliopsoas is often placed in a shortened position, which can lead to tightness and restriction in the range of motion at the hip joint. This condition commonly results from prolonged sitting or inadequate stretching of the hip flexor muscles, impacting activities such as standing up straight, walking, or running.

While other muscles like the rectus femoris also play a role in hip flexion, their primary function relates to the knee joint, as the rectus femoris crosses both the hip and knee. The gluteus maximus primarily functions to extend and externally rotate the hip, so it is not directly involved in flexion. The tensor fasciae latae assists with hip flexion but is not the primary muscle responsible for the hip flexor action. Thus, the iliopsoas is specifically identified as the muscle most affected by hip flexor contracture.