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Ritter, Merrill, A.

Clinical Orthopaedics and Related Research: November 2003 - Volume 416 - Issue - p 110
doi: 10.1097/01.blo.0000093877.12372.38
SECTION I SYMPOSIUM: Papers Presented at the Knee Society 2003

From the Center for Hip and Knee Surgery.

Reprint requests to Merrill A. Ritter, MD, 1199 Hadley Rd., Mooresville, IN 46158. Phone: 317-831-2273; Fax: 317-831-9347; E-mail:

Total knee replacement (TKR) has a very high success and survival rate with the right indicators. However, there are many individuals with unusual indications that still may need our attention. The survival rate for TKRs lasting approximately 15 years is greater than 95% for cruciate-retaining, cruciate-substituting, and mobile-bearing designs. What is successful, however? How do we describe it? Pain, ROM, stability, loosening, revision? Is one knee or design better than another?

All knee types and designs have high pain-free objectives and results. The kinematics in years past were poor. However, today despite the type of design, they have improved remarkably. Does the prosthesis make the difference?

Three basic designs (cruciate-retaining, cruciate-substituting, mobile-bearing) all have shown good long-term survival rates, but is one better than another?

Unfortunately, TKRs fail and require revision. What have we learned during the past 30 years? Is the revision rate less and what have we done to improve these results?

Cruciate-retaining knee replacements must depend on the PCL for posterior stability. However, the cruciate-substituting TKR requires a post for similar stability. Is the post a source of problem? Does it wear? Does too much force transmit to the fixation interface through it?

There have been patients with pain who have been denied the success of a TKR because of unusual diagnoses. As we improve our design and fixation, does this also allow us more freedom as to what patients receive such implants?

There are more than 267,000 TKRs done annually in America with success rates of approximately 90% to 95%. 1 Through research and data as reported here, hopefully these results will even improve.

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1. Ritter MA, Meding JB: Editorial comment. Clin Orthop 388:2, 2001.
© 2003 Lippincott Williams & Wilkins, Inc.