A femoral head arthroplasty system can comprise a femoral prosthesis comprising a mounting plate having a first side and an opposed second side. An adapter can extend from the second side of the mounting plate. An implant body can extend from the first side of the mounting plate. The implant body can extend from the mounting plate by a distance no greater than 90 mm. The femoral head arthroplasty system can further comprise a femoral head replacement having a generally spherical surface and comprising a recess that is shaped to complementarily receive the adapter of the femoral prosthesis.

A femoral head arthroplasty system can comprise a femoral prosthesis comprising a mounting plate having a first side and an opposed second side. An adapter can extend from the second side of the mounting plate. An implant body can extend from the first side of the mounting plate. The implant body can extend from the mounting plate by a distance no greater than 90 mm. The femoral head arthroplasty system can further comprise a femoral head replacement having a generally spherical surface and comprising a recess that is shaped to complementarily receive the adapter of the femoral prosthesis.

An intervertebral disc includes a superior endplate having an upper vertebral contacting surface and a lower bearing surface, wherein the upper vertebral contacting surface of the superior endplate has a central portion that is raised relative to a peripheral portion of the superior endplate, and wherein the lower bearing surface has a concavity disposed opposite the raised central portion. The disc includes an inferior endplate having a lower vertebral contacting surface and an upper surface, wherein the lower vertebral contacting surface of the inferior endplate has a central portion and wherein the upper bearing surface has a concavity disposed opposite the central portion. A core is positioned between the upper and inferior endplates, the core having upper and lower core bearing surfaces configured to mate with the bearing surfaces of the upper and inferior endplates. The upper vertebral contacting surface of the superior end plate has a different shape than the lower vertebral contacting surface of the inferior end plate.

An expandable interbody device used as a prosthesis during spinal surgery. The expandable interbody device is configured to be inserted into the space between spinal discs to provide stability. The expandable interbody device includes a drive block, a top endplate, a bottom endplate, a first drive arrangement, and a second drive arrangement; the first drive arrangement includes a first drive screw, a first left side slide, a second left side slide, a first upper left side linkage, a second upper left side linkage, a first lower left side linkage age and a second lower left side linkage; and the second drive arrangement includes a second drive screw, a first right side slide, a second right side slide, a first upper right side linkage, a second upper right side linkage, a first lower right side linkage and a second lower right side linkage.

An expandable interbody device used as a prosthesis during spinal surgery. The expandable interbody device is configured to be inserted into the space between spinal discs to provide stability. The expandable interbody device includes a drive block, a top endplate, a bottom endplate, a first drive arrangement, and a second drive arrangement; the first drive arrangement includes a first drive screw, a first left side slide, a second left side slide, a first upper left side linkage, a second upper left side linkage, a first lower left side linkage age and a second lower left side linkage; and the second drive arrangement includes a second drive screw, a first right side slide, a second right side slide, a first upper right side linkage, a second upper right side linkage, a first lower right side linkage and a second lower right side linkage.