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Mark Gebhardt, MD
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Second Session
Moderator: Mark Gebhardt, MD
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| James Huddleston, MD |
Thomas Thornhill, MD |
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Zone 4 Radiolucency in Paired Cemented and Cementless Femoral Total Knee Components
James Huddleston, MD
Advisor: Richard Scott, MD
Discussor: Thomas Thornhill, MD
A series of patients who had had bilateral simultaneous total
knee replacements, cemented on one side and uncemented on the other, were
compared by plain radiograph for an average follow up of 7.6 years. They found
fewer zone 4 lucencies in uncemented femurs than in cemented ones.
Dr. Thornhill asked if there were selection bias, for instance
if those femurs selected for cementing may have had poor contact in Zone 1, or
if cemented knees were those where the femur had been cut poorly overall. He
also asked whether the radiolucencies had been shown to be progressive, and
whether it could be determined if they were medial or lateral. He asked whether
distal stress shielding was noted in the non-cemented group. Finally, he asked
what was the role of the non-cemented femur in this day and age. Dr. Nunley
pointed out it is hard to evaluate radiolucency in a non-cemented femur, and
also suggested that computer-aided cutting may render all cuts "perfect" and
thus obviate the need to evaluate cut quality intraoperatively. Dr. Rubash also
pointed out that the implant-cement interface reflects a mechanical process,
while the bone-cement interface reflects a biologic one, and so inferences about
these two must be considered in a separate fashion.
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| Robert Parisien, MD |
Charles Brown, MD |
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The Long Term Outcome of Allograft Anterior Cruciate Ligament Reconstruction
Robert Parisien, MD
Advisor: William Tomford, MD
Discussor: Charles Brown, MD
The results of 89 consecutive fresh-frozen tibialis anterior
and tibialis posterior allograft ACL reconstructions performed by a single
surgeon from 1985 to 1998 were reviewed and patients were evaluated by mail
follow up using the IKDC and SF-36, which are validated subjective outcome
instruments. Follow up was obtained in 83.5% of this cohort. 87.3 % of these
patients were satisfied with the results of the surgery.
Dr. Brown, praised this paper for addressing the "two most
controversial questions in ACL research" – what graft to use, and how to
evaluate results. He suggested the study's strengths were that a single
surgeon had performed all the surgeries, with an unvarying technique with
very long term follow up. Dr. Nunley agreed with this praise, adding that
he was amazed at the senior surgeon's prescience twenty years ago to have
picked the current state-of-the-art technique, and his persistence in sticking
with it. Dr. Brown acknowledged that although subjective patient satisfaction
was an important outcome to track, he criticized the authors for failing to
include objective measures of graft longevity and performance. Dr. Nunley
contested this point, saying that patient satisfaction was the most important
outcome measure. Dr. Brown also pointed out that the long-term infectious
risk of allograft human tissue is unknown, and must be considered to be
higher than that for autograft, a point that Dr. Nunley echoed. Dr. Tomford,
advisor for this project and director of the MGH bone bank, gave a brief
explanation of how the allografts are sterilized.
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