Why registries analysing cruciate ligament surgery are important

National quality registries have been used in several medical specialties to improve healthcare worldwide.1–8 Owing to the inferior clinical results associated with some hip prosthesis designs in the early 1980s,6 nationwide Hip Arthroplasty Register (Norwegian Arthroplasty Register, NAR) was established in Sweden, in 1979, and in Norway, in 1987, with implant revision as the main end point.1 The purpose is the early detection of inferior results caused by implants, cements or surgical techniques.1 ,3 ,6 In 1994, the Norwegian registry was expanded to include all joint replacements.3 In 1995, two studies1 ,3 described implant inferiority at an early stage, a finding only possible through registry studies. The Hip Arthroplasty Register is based on a simple reporting system (approximately 1 min to complete a single-page registration form) and hospitals are provided with continuous feedback from the registry.1 ,2 These two factors are believed to explain why the compliance rate of nearly 100% has not declined during 30 years of operation.1 ,2 Immediately after each operation, the surgeon completes the registration form, which is mailed to the NAR office. Patient identification and the different procedures, including the type of implant and cement used, are specified on the registration form. Feedback to the surgeons and recently to the public is given as annual national reports. In addition, each hospital receives a report on its own activities and results, which can be compared to the national average. A wide range of studies have been published based on the NAR database.1 ,3 ,6 To date, national registries have been established in Norway, Sweden (1979), Finland (1980), Denmark (1995), Australia (1999), New Zealand (1999), Canada (2000), Romania …