This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow CME: Take the exam for this article:
 Adult Knee Reconstruction Test 1: Revision Total Knee Arthroplasty
Right arrow Letters to the Editor: Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when Letters to the Editor are posted
Right arrow Alert me if a correction is posted
Services
Right arrow E-mail this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My File Cabinet
Right arrow Download to citation manager
Right arrowReprints and Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ward, W. G.
Right arrow Articles by Eckardt, J. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ward, W. G.
Right arrow Articles by Eckardt, J. J.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us   Add to Technorati  
What's this?
The Journal of Bone and Joint Surgery (American) 85:448-453 (2003)
© 2003 The Journal of Bone and Joint Surgery, Inc.

Scientific Article

Dislocation of Rotating Hinge Total Knee Prostheses

A Biomechanical Analysis

William G. Ward, MD, David Haight, MD, Paul Ritchie, MD, Stan Gordon, BS and Jeffrey J. Eckardt, MD

Investigation performed at the Department of Orthopaedic Surgery, Wake Forest University Baptist Medical Center, Winston-Salem, North Carolina

William G. Ward, MD
David Haight, MD
Paul Ritchie, MD
Stan Gordon, BS
Department of Orthopaedic Surgery, Wake Forest University Baptist Medical Center, Medical Center Boulevard, Winston-Salem, North Carolina 27157-1070. E-mail address for W.G. Ward: wgward{at}wfubmc.edu

Jeffrey J. Eckardt, MD
Department of Orthopaedic Surgery, University of California at Los Angeles School of Medicine, 10833 Le Conte Avenue, Los Angeles, CA 90024

The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. None of the authors, nor any affiliated agencies, foundations, etc., have received any payment, grant, research support, or other financial support or payment related to this work. However, W.G. Ward received research support for other projects (during the time course of this project) from DePuy, Sulzer, and Howmedica, and he has performed paid consultant work for Howmedica. W.G. Ward was an oncology product design team consultant (designer) for Sulzer Medica. J.J. Eckardt is a consultant for Howmedica and has received grant funding from Howmedica. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated. All seven manufacturers supplied sample knee implants for the biomechanical testing.

Background: Symptomatic instability and implant dislocation are occasionally encountered in patients with a rotating hinge total knee prosthesis. A biomechanical study of rotating hinge total knee implants was performed to determine the association between the design (length and taper) of the central rotational stem and the stability of the implant.

Methods: The stem lengths and tapers of knee implants made by seven manufacturers were measured. The tilting laxity of each design was tested by measuring the degree of tilting of the central rotational stem within the tibial housing that occurred with increasing amounts of distraction. The maximum amount of distraction that was possible before the stem dislocated was determined for each design.

Results: Implant designs with a short and/or markedly tapered central rotational stem had the greatest tilting, laxity, and instability of that stem. The Howmedica, Techmedica, Intermedics/Sulzer Medica, and Wright Medical Technology/ Dow Corning Wright designs required 39 mm of distraction before they dislocated. The Biomet knee implant required 33 or 44 mm of distraction to dislocate, depending on the thickness of the polyethylene tray that was utilized. The S-ROM knee required only 26 mm of distraction before dislocation occurred.

Conclusions: The measurements confirmed that the shorter the stem and the greater its taper, the greater the instability and laxity at any given amount of joint distraction.

Clinical Relevance: Rotating hinge knee designs with a short, tapered central rotational stem (in the absence of a mechanical stop to distraction) should be used with caution in patients with bone and soft-tissue compromise that may allow excessive distraction and implant dislocation, especially when the patient has a flexion-extension gap mismatch or a flexion gap laxity.



Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Technorati Technorati    What's this?


This article has been cited by other articles:


Home page
 J Am Acad Orthop SurgHome page
D. A. Dennis, D. J. Berry, G. Engh, T. Fehring, S. J. MacDonald, A. G. Rosenberg, and G. Scuderi
Revision Total Knee Arthroplasty
J. Am. Acad. Ortho. Surg., August 1, 2008; 16(8): 442 - 454.
[Abstract] [Full Text] [PDF]

Home page
 JBJSHome page
W. G. Ward, D. Haight, P. Ritchie, S. Gordon, and J. J. Eckardt
Dislocation of Rotating Hinge Knee Prostheses. A Report of Four Cases
J. Bone Joint Surg. Am., May 1, 2005; 87(5): 1108 - 1112.
[Full Text] [PDF]