The meniscus Arrow or metal screw for treatment of osteochondritis dissecans? In vitro comparison of their effectiveness.

Three draw bench tests in axial direction were conducted of the pull out forces in predrilled human condylar bone of one single meniscus Arrow, one single metal screw, and three Meniscus Arrows in one bone block, the Arrows being inserted using the standard hand instruments. Bone blocks with three meniscus Arrows were tested additionally in tangential direction, imitating shear forces. All observed values were within the range of 1 standard error (SE) or higher and exceeded the values in meniscal tissue as reported in the literature. These are much higher than the shear force during a single movement in the human knee. Most metallic devices used for fixation of the fragments in the treatment of osteochondritis dissecans must be removed in a second operation. Left in place, as with the Herbert screws, they can disturb future imaging and damage the opposite cartilage of the tibia plateau. Staples left in place can break. Finally, some metals evoke allergic reactions and, at least in animals, are potent carcinogens. Although fusion of osteochondritis dissecans fragments in their original locations fixed with noncompressive biodegradable pins has been reported, these tests show the hold of compressive meniscus Arrows in bone to contribute to a better result than noncompressive pins. Other biodegradable devices are also available for this application. However, one advantage is that using meniscus Arrows, already available in the hospital for mending ruptured menisci, saves the costs of investing in other sets of instruments and devices. Another advantage is the smaller diameter of the meniscus Arrows than that of other biodegradable devices, resulting in less damage to the fragments.