The Journal of Bone and Joint Surgery (American). 2007;89:1269-1274.
doi:10.2106/JBJS.F.00376
© 2007 The Journal of Bone and Joint Surgery, Inc.
Total Elbow Prosthesis Loosening Caused by Ulnar Component Pistoning
Emilie V. Cheung, MD1 and
Shawn W. O'Driscoll, PhD, MD2
1 Department of Orthopedic Surgery, Stanford University, 300 Pasteur Drive,
Edwards R-155, Stanford, CA 94305-5335
2 Mayo Clinic, 200 First Street, MSB 3-69, Rochester, MN 55905. E-mail address:
odriscoll.shawn{at}mayo.edu
Investigation performed at the Mayo Clinic, Rochester,
Minnesota
Disclosure: The authors did not receive any outside funding or
grants in support of their research for or preparation of this work. One or
more of the authors, or a member of his or her immediate family, received, in
any one year, payments or other benefits of less than $10,000 or a commitment
or agreement to provide such benefits from a commercial entity (Tornier). No
commercial entity paid or directed, or agreed to pay or direct, any benefits
to any research fund, foundation, division, center, clinical practice, or
other charitable or nonprofit organization with which the authors, or a member
of their immediate families, are affiliated or associated.
Background: Linked semiconstrained total elbow prostheses have been
used successfully but may be at higher risk for implant loosening than
unlinked implants are. The purpose of the present report was to describe a
previously unreported and potentially preventable cause of mechanical
loosening of the ulnar component of a linked total elbow prosthesis.
Methods: A series of ten patients who had painful pistoning of the
polymethylmethacrylate-coated ulnar component of a Coonrad-Morrey linked total
elbow prosthesis were evaluated clinically and radiographically.
Results: All ten patients complained of elbow pain, and eight had a
distinct sensation of the ulnar component moving within the ulna. Six patients
either complained of squeaking within the elbow or could demonstrate squeaking
on examination. Four patients had a complete radiolucent line around the ulnar
component or the cement mantle, and six had an incomplete line around the
ulnar component. Six patients had a radiolucent gap between the cement and the
tip of the ulnar prosthesis. Two patients had proximal migration of the ulnar
component within the cement mantle on lateral flexion radiographs. Three
patients had anterior impingement, such as between the anterior flange of the
humeral implant and a prominent coronoid process, on lateral flexion
radiographs. At the time of revision arthroplasty, all ten patients were found
to have a loose ulnar component, which was successfully revised with or
without impaction grafting. At the time of the most recent follow-up, nine of
the ten ulnar components were intact and stable. Three patients required an
additional reoperation: one required triceps repair, one required revision of
a loose humeral component, and one required a revision total elbow
arthroplasty.
Conclusions: Pistoning of the ulnar component in the cement mantle
leading to failure by means of a pullout mechanism can occur in association
with the Coonrad-Morrey total elbow prosthesis with a
polymethylmethacrylate-precoated ulnar component. To prevent this problem
following any total elbow arthroplasty, the surgeon should check for anterior
impingement intraoperatively by ensuring that there is no contact between the
anterior flange and a prominent coronoid process or the cement and that no
distraction of the trial ulnar component from the ulna occurs with passive
elbow flexion. This condition also can be avoided by ensuring that the ulnar
component is not inserted too far distally. This mechanism of failure should
be considered when future total elbow arthroplasty implants are designed.
Level of Evidence: Therapeutic Level IV. See Instructions
to Authors for a complete description of levels of evidence.

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