Why does Perthes disease cause limping?

Perthes disease affects the developing ball of the hip joint. During the condition, the hip may become painful or stiff, particularly when the child moves the leg outward or rotates it. The body may shorten the time spent standing on that side, take smaller steps, or tilt the trunk to reduce hip loading.

The limp can be more noticeable after activity and may occur with groin, thigh, or knee discomfort rather than pain at the hip itself. Limping is a common presentation of Perthes Disease, but a limp in a child has many possible causes and needs assessment.

Keep follow-up appointments with the child's orthopaedic team and follow their advice about activity, weight-bearing, and movement. Do not force painful hip stretches or assume the child is simply tired. A physiotherapist may prescribe gentle mobility work and exercises that protect comfortable hip movement.

Note when the limp appears, whether pain follows activity, and whether the child avoids running or stairs. This information helps the care team adjust the plan.

Arrange prompt medical assessment for a new or persistent limp, even when pain is mild. Seek urgent care if the child cannot bear weight, has severe pain, fever, a hot or swollen joint, looks acutely unwell, or develops symptoms after an injury.

Ask which activities are safe, how much hip movement should be maintained, and what changes should trigger an earlier review. Ask how the team will monitor walking, hip motion, and the shape of the developing joint.