Arthroplasty has become a very successful operation with excellent long-term results. A dedicated diagnostic set-up to exclude osteoporosis prior to a joint replacement and the use of drugs to improve the outcome of a joint replacement are currently not recommended. Knee arthroplasty should always be cemented in patients with known osteoporosis. The same is recommended for hip joint replacement, even if the cement-free acetabular component yields good results. Rapid loading and mobilization appear beneficial also with respect to the osteoporosis and its systemic treatment.