The Altus Spine Monaco HA Pedicle Screw System has a low profile which accepts 5.5mm and 6.0mm CoCr and titanium rods. The Monaco HA screws have hydroxyapatite (HA) coating over the entire thread length. The HA coating largely consists of calcium and phosphorus, and is intended to enhance the fixation between the pedicle screw and the surrounding bone. In addition, the bone screw thread design optimizes thread purchase and pull out strength, and has a friction fit with the screw head so it remains in the appropriate position for rod implantation.