CORR Insights®: Weightbearing and Activity Restriction Treatments and Quality of Life in Patients with Perthes Disease

Where Are We Now? The wide range of treatment modalities for Perthes disease includes restricted weightbearing, which is based on the belief that even normal axial loading will worsen the collapse of the femoral epiphysis. Surgeons offer restricted weightbearing regimens of different magnitudes and durations. Although there is a dearth of evidence in support of modified axial loading for those with Perthes disease, the concept is routinely practiced, with the goal of minimizing asymmetric epiphyseal loading. In particular, many advise against such activities as jumping, contact sports, or tennis. But any restricted weightbearing benefits must be balanced against potential risks, such as adverse effects on mental health. Understanding these risks is important in evaluating the tradeoffs associated with the recommendations we make to children with Perthes disease and the associated burdens for them and their caregivers. In their series of 210 children with Perthes disease, Do et al. [2] examined the impact of restricted weightbearing and activity on physical and mental health and social well-being. All completed a valid and reliable patient-reported outcome measure while in Waldenstrom [6] stages I, II, or III of Perthes disease. The authors assessed mental health (feelings of depression and anxiety), social health (participation in their social roles and peer activities), and pain. Children treated with non- or reduced weightbearing and activity restrictions showed no differences when compared with those who were allowed unrestricted activity. This is an important finding because it justifies interventions that are based on restricted weightbearing to further scientific evaluation. Additionally, their results enable more-informed counseling of children and their caregivers who may be perplexed about the idea of prolonged use of crutches and abstinence from a wide range of sports. This study is timely considering the growing concern around youth mental health, where physical activity among adolescents has been linked with improved mental health [1]. In light of its findings, surgeons who have been practicing restricted weightbearing regimens for Perthes disease can reassuringly continue to do so. Where Do We Need To Go? Larger studies, done prospectively, that administer patient-reported outcome measures periodically throughout the disease would extend upon the current study’s results. The direction of the association will probably not change in a larger study compared with Do et al. [2] because their data show nearly identical scores for the subscales that matter most; however, such research would enhance the conclusions about the magnitude of the effect estimates and provide insight into within-person changes over time. Do et al. [2] offer reassurance that restricted weightbearing, in one form or another for a considerable time, had no measurable adverse effects. Confirmation of this in a different and larger sample would be beneficial; external validity is always important to ensure. Such studies would benefit also from some clever thinking on how to measure the children’s compliance and the risk of undesired cointerventions. The current study’s results provide the foundation for robustly designed research to both evaluate interventions that are based on reduced axial loading and to address a big question: Is prolonged activity restriction beneficial for those with Perthes disease? How Do We Get There? With the availability of the data from the study by Do et al. [2], preferences for treatment can be elicited as a next step in evaluating this intervention. For example, a discrete choice experiment would potentially yield answers on what affected patients are willing to give up in terms of mobility as well as daily and recreational activities to increase their chances of a good outcome. However, such work would rely largely on available data and would thus give rather uncertain estimates. The randomized trial is the only design that will deliver robust answers about the effects of non- or reduced weightbearing regimens in treating Perthes disease. Such a trial would not require very long follow-up time for the participants, because with the Stulberg classification [4] we have a proxy measure that enables inferences about premature osteoarthritis, the endpoint that truly matters. As with other successful trials on pediatric conditions, this would require multicenter collaboration. Peto’s concept of “large simple trials” [3] is characterized by trials with large sample sizes, broad entry criteria, streamlined data collection, objectively measured endpoints, and follow-up that mimics normal practice. It appears there is considerable interest in the topic among patients, parents, allied health professionals, and surgeons for such work [5].