1. Field of the Invention
The present invention relates to a bone void filler, and more particularly, a bone void filler having a designed shape, porosity, pore distribution and material composition to provide enhanced bone healing and ingrowth, and a method of manufacturing the bone void filler.
2. Description of the Related Art
Bone fractures and defects can be difficult to heal in certain circumstances. If a defect or gap is larger than a certain critical size, natural bone is unable to bridge or fill the defect or gap. Accordingly, it is of interest to fill such voids with a substance, traditionally referred to as a bone void filler, which helps the void to eventually fill with naturally grown bone. The bone void filler may be a collection of pieces of either random or designed shape. Existing bone void filler products include a product called Vitoss made by OrthoVita (Malvern, Pa.), and a product called ProOsteon made by Interpore. A known shape of bone void filler piece is jacks or tetrapods under the product name OsteoSet or Jax made by Wright Medical. The shape of the Vitoss product pieces is random, formed by fracturing (comminuting) larger porous pieces. The Jax product is formed by powder compaction.
As far as material composition, bone void fillers have been both resorbable and nonresorbable. Among the calcium-phosphorus compounds that resemble the mineral content natural bone are hydroxyapatite, beta-tricalcium-phosphate, alpha-tricalcium-phosphate and the like.
Among the factors which are believed to contribute to making a good bone void filler material are the proper time scale for the bone void filler to resorb or decompose in the human body, the proper size and distribution of pores in the bone void filler, the proper void fraction, and a suitable surface geometry. Ultimately, the criterion for a good bone void filler may be the amount and quality of natural bone that eventually grows in and among and in place of the bone void filler owing in large part to the configuration of the bone void filler.
Accordingly, it would be desirable to create a bone void filler which does a better job of inducing the growth of natural bone to fill a defect of void. To this end, it would be desirable to create a bone void filler that is a collection of pieces each of which has a shape which lends itself to packing to a fairly large geometric packing density of the overall pieces. It is also desirable to create a bone void filler that has characteristics of easy handling and placement for the surgeon. It may also be desirable that the bone void filler pieces have certain surface geometry or roughness features on at least some of their surfaces. It may also be desirable to create a bone void filler which has a somewhat narrow pore size distribution. It may be desirable that the bone void filler be made largely of resorbable material. It may be desirable to provide both osteoconductive and osteoinductive properties of the bone void filler.