Test whether an intervention, consisting of frequently feedback of performance outcomes and education will improve patient care, expressed in better functional outcomes, fewer complications and more quality improving interventions.

A randomized controlled trial will be conducted where hospitals will be randomized to an early versus late group, stratified by teaching status as this might influence the time available for quality improvement. Randomization will be done using a computer generated randomization table in a 1:1 ratio. During the study only orthopedic surgeons performing THA and TKA will receive monthly feedback by email.

The intervention will consist of the following components:

• Monthly feedback of performance outcomes;
• Education on how to use joint registry data for quality improvement;
• Create awareness by sending monthly feedback about performance; education and by asking what improvement activities have been introduced;
• Hospitals will be linked to hospital with opposite performance outcomes to exchange information and find areas for improvement.

During the trial, the investigators will conduct monthly measurement on intermediate outcomes showing whether the intervention reaches the target group (process evaluation). The following measurements will take place:

• Knowledge among orthopaedic surgeons on their recent performance and how that relates to others;
• Number of quality improvement activities undertaken with the aim to improve the quality of care;
• Planned improvement activities (e.g. record review to figure out why performance is not as good as in other centers) together with who is responsible and by which time;
• Number of people attending the meetings, number of times a specific account has accessed the LROI site to ensure that information has reached the target group;
• Survey among orthopaedic surgeons at the end of the intervention period on knowledge learned and the extent to which they think this is sustainable in daily practice.

In addition, the investigators will compare the outcomes between the early and the late group to test the effectiveness of the intervention, using the appropriate regression techniques. In the second period the investigators will test the sustainability of this approach in daily practice by comparing the outcomes within the early group with the first period, and compare with the late group to test whether outcomes in the sustainability phase are similar as when actively supported.

Inclusion Criteria:

• All Dutch orthopedic clinics where hip- and knee replacement surgery is performed who agree to participate will be randomized.

Exclusion Criteria:

• None

This is about the performance of hospitals. The individual performance of a hospital will not be announced.