What should you know about Perthes disease stages?

The stages are commonly described as loss of blood supply and bone weakening, fragmentation, healing or re-ossification, and residual remodelling. The timetable varies between children. Stage names alone do not determine the outlook; age, hip movement, joint containment and the final shape are also considered.

Early changes may bring a limp, hip or groin discomfort, or reduced movement. During fragmentation, the weakened ball of the hip can become vulnerable to flattening or loss of fit. In re-ossification, new bone forms and the hip gradually becomes stronger. Remodelling is the longer period when growth can refine the shape. Regular examination and imaging show whether the ball remains well covered by the socket.

Care aims to preserve comfortable movement and a good fit between the hip’s ball and socket. This may include limiting running or jumping, using prescribed pain relief, and keeping the hip moving with paediatric physiotherapy. Some children need closer containment treatment or an operation, particularly when movement is restricted or alignment is difficult to maintain. Follow the activity plan even when the child seems comfortable.

Arrange medical review for a new limp, persistent hip or knee pain, reduced ability to spread the legs, or a child who avoids normal play. Seek prompt advice if symptoms worsen suddenly, walking becomes very difficult, or fever follows an injury or procedure. These features can have causes other than Perthes disease and need direct assessment.

Ask which stage the hip appears to be in, what the X-rays show about containment, which movements should be protected, how often review is needed, and what would change the treatment plan.