No adverse effects of bone compaction on implant fixation after resorption of compacted bone in dogs

Background A new bone preparation technique, compaction, has been shown to enhance initial implant fixation. However, short-term compaction has resulted in more non-vital bone being in contact with the implant. Also, compaction may result in inferior long-term implant fixation as the compacted non-vital bone at the bone-implant interface is resorbed.

Methods We tested the hypothesis that compaction would result in inferior implant fixation after 10 weeks of weight bearing. We compared compaction with the conventional bone removal technique (drilling) for (1) porous coated titanium (Ti) implants inserted exact-fit into medial femoral condyles, and for (2) hydroxy-apa-tite (HA) porous coated implants inserted press-fit into lateral femoral condyles. In each of 8 dogs, we prepared the implant cavities of one knee joint with drilling, and the other with compaction. Implants were tested mechanically to failure by push-out test, and histomor-phometry was done.

Results For all specimens, non-vital bone implant contact contributed very little to the total bone implant contact. Inferior mechanical or histological implant fixation with compaction was not found for either Ti implants or HA implants.

Interpretation Compaction does not appear to result in inferior implant fixation as the compacted bone at the bone implant interface is resorbed.