OPNon-STOP (Operative or Non-Surgical Treatment of Perthes’ disease)

http://www.OPNonSTOP.org

Perthes’ disease is a rare condition of the hip joint and one of the most disabling conditions affecting children. To understand Perthes’ disease, it is important to know that the hip is a ‘ball and socket’ joint - this can be thought of as a ball of ice-cream, (the ‘hip bone’) sitting in an ice-cream scoop (the ‘socket’). Perthes’ disease is caused by a problem with the blood supply to the hip bone, which means the ball doesn’t get enough oxygen and nutrients to grow. When this happens, the hip loses its strength and flattens - like the ice-cream melting and becoming squashed. In Perthes’ disease there is a temporary loss of blood supply, which means that after some months the nutrients return, and the ball again hardens. However, the bone remains whatever shape it was when it became squashed. This can lead to a ball that doesn’t fit well into the socket, which can cause pain, limitation to usual activities and severe hip arthritis in childhood.

About half of the surgeons in the UK believe that surgery can be helpful in ‘controlling’ the way that the ball flattens. Surgery involves breaking the bone to re-orientate the hip joint to ensure that the ball deforms in a controlled way into the scoop (called ‘containment’ surgery). The other half of surgeons do not undertake surgery, instead focusing on a package of care keeping the child active, which involves physiotherapy, activity restriction and pain relief (called active containment’). Active containment aims to maintain movement of the hip and keep the soft ball moving within the scoop, allowing it to continually smooth its shape.

We would like to understand if surgical containment is better than active containment, in terms of the how well a child is able to function 3 years after they enter the study.

Summary

216 children aged five years to twelve years inclusive with newly diagnosed Perthes’ disease will be invited to take part in the study. This study will compare children having ‘containment surgery’ to children having ‘active containment’ and specifically look at how well children are able to take part in activities three-years after joining the study.

Background to the trial

Perthes’ disease is an idiopathic avascular necrosis of the developing femoral head, predominantly affecting boys (4:1 male-to-female ratio) aged 4 to 12 years old. It causes collapse of the femoral head, leading to severe pain and disability for 2–3 years until the hip re-ossifies. The condition often results in long-term hip deformity, chronic pain, disability, and premature osteoarthritis, frequently necessitating hip replacement in early adulthood. Despite being one of the most common conditions treated by children’s orthopaedic surgeons, Perthes’ disease remains poorly understood.

The UK has the highest global incidence, with children in Northern England at the greatest risk. Around 1 in 1,200 children in the UK develop Perthes’ disease, with 500 new cases annually. The disease is strongly linked to socioeconomic deprivation, though its exact cause is unknown.

A key treatment principle is ‘containment,’ ensuring the femoral head remains within the acetabulum to allow re-ossification in a rounded shape. There are two primary methods of containment practiced by surgeons. ‘Surgical containment’ involves a procedure, such as a femoral or pelvic osteotomy, often paired with tendon releases to optimise the position of the hip within the socket – this aims to control the collapse of the femoral head. Alternatively, 'Active containment' uses physiotherapy, activity modification, and pain relief, to ensure the child keeps active, encouraging hip movement to help control collapse. There is international debate about the optimal treatment, with no randomised trials to compare these approaches, leaving treatment decisions dependent on surgeon beliefs.

The UK-wide BOSS study is the most robust investigation to date, but significant uncertainty remains. The James Lind Priority Setting Partnership and the British Society of Children’s Orthopaedic Surgery have identified research on the need for surgery in Perthes’ disease as a top priority.

Aims and objectives

At the end of the study, we aim to know if surgical containment is better than active containment children diagnosed with with Perthes’ disease.

Study design

This study will aim to recruit a minimum of 216 patients with Perthes’ Disease, between 5 and 12 years old. It is anticipated that 30 hospitals will become recruiting centres.

After providing consent and baseline data, patients will be fairly allocated (1:1) to either surgical containment or active containment. The randomisation process will be stratified for: age group (5-7 years, 8-12years), sex and degree of collapse of the lateral column (<50%, 50%, >50%).

All children and young people will be followed-up for three-years to monitor their hip. Function will be the primary outcome at 3-years. They will also be asked about pain, if they needed any more surgery, school attendance, any complications, the number of hospital visits, their quality of life and satisfaction with care. Participant follow-up will be organised by the University of Oxford – either electronically by email, text message or by telephone.

The recruitment period is approximately 3 years.