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Mark Gebhardt, MD
 
Second Session
 Moderator: Mark Gebhardt, MD
James Huddleston, MD Thomas Thornhill, MD
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.
 

Robert Parisien, MD Charles Brown, MD
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.
 

Links of interest: