Quality health care has many definitions. Among those definitions is "care that consistently contributes to the improvement or maintenance of the quality and/or duration of life." The current evolution in health care has been fueled by three necessities frequently demanded by payers and employers: improvement in access, lowering of cost, and definition and quantification of the quality of care. This evolution has been facilitated by the so-called industrialization of medicine. This concept includes the adoption of industrial economic principles and techniques that facilitate the measurement of processes and outcomes. Quality health care is currently recognized as health care that is characterized by three elements: the use of practice guidelines or standards, the implementation of continuous quality improvement techniques, and the use of outcome determination and management. Practice guidelines demand the adoption of evidence-based principles in evaluation and care, as well as minimization of variations in evaluation and care. Continuous quality improvement seeks to determine why variations in processes of care occur and then to minimize those variations. Outcomes may be measured in terms of both very objective and very subjective variables and also on the basis of cost-efficiency. Most tools currently used to quantify outcomes, especially in orthopaedics, involve measurements of general health and of specific body part or organ system function. This evolution in health care is producing significant alterations in methods of traditional health-care delivery. The accumulating evidence indicates that these changes, although frequently unpopular, are improving the quality of health care.