TECHNICAL FIELD The present invention relates to allograft packaging systems, and more particularly to bone allograft packaging systems.

BACKGROUND OF THE INVENTION Bone allografts are used in a variety of medical procedures, e. g., spinal fusion procedures. Such bone allografts need first to be processed at a sanctioned facility and then are provided to medical facilities that perform the procedures. These processing facilities may shape bone allografts and then package them for transportation to medical facilities.

Commonly, the bone allografts are either: (1) fresh frozen or (2) freeze dried prior to packaging and transportation to a medical facility. Disadvantages exist with both of these approaches. Specifically, fresh frozen bone allografts must be continuously stored at low temperatures (ie: frozen) both when stored and when transported to the medical facility to ensure their suitability for future medical procedures. Disadvantages of requiring such refrigerated storage include both the cost incurred in operating such equipment and the preparation time required in thawing the allografts for use at the start of the medical procedure. On the other hand, when using freeze dried bone allografts, the bone allografts must be re-hydrated prior to use in a medical procedure (which may require some time).

Moreover, during the re-hydration process, the bone allograft must be kept in a sterile environment. Due to the time required either to thaw fresh frozen bone allografts or to re- hydrate freeze dried bone allografts, the thawing/re-hydration of the allografts must be commenced a period of time prior to actually starting the medical procedure, thus increasing the overall time required to perform the surgical procedure.

A further disadvantage of using a freeze dried bone allograft is that the freeze- drying process reportedly reduces the mechanical properties of the bone (for example, its compressive strength and rigidity). Rehydrating the bone is reported to restore only about

90% of the original properties, and this restoration is dependent on physician compliance with the rehydration process.

Moreover, in certain medical procedures the size or shape of the bone allograft required may not be known a priori. Consequently, several different size/shape bone allografts may need to be thawed/re-hydrated prior to the medical procedure. Those allografts not used during the procedure then need to be discarded. This is an inefficient use of a limited resource (bone allograft) and is time consuming. Accordingly, a need exists for an improved system for packaging bone allografts for future medical procedures, and in particular a system in which the allografts can be readied for surgical use much more quickly than with existing methods.

The present invention includes systems for packaging and storing bone allograft material for future use in a medical procedure. In accordance with the present invention, the bone allograft may be placed in a container. In various aspects of the invention, this container may comprise glass, plastic, or a metal foil. A saline solution may be added to the container. In one aspect of the invention, the amount of saline solution added is preferably just sufficient to keep the bone allograft hydrated. In one preferred aspect of the invention, the saline solution is saturated with minerals to minimize the leaching of minerals from the bone over time. The saturation of the saline solution may be accomplished with any combination of minerals, including, but not limited to, calcium, phosphate and magnesium.

After placing the bone allograft in a saline solution in the container, the container may then optionally be closed with an airtight seal. Prior to the medical procedure, the bone allograft is then simply removed from the container for use. In one optional aspect of the invention, the bone allograft may be sealed in a container with solution then added to the container via a self-sealing valve. In one approach, air may be vacuumed from the container prior to closing the container. When using this approach, a"shrink-wrap"type of container may be used in which the container conforms to the shape of the allograft as the air is vacuumed out.

Although not required by the present invention, the bone allograft may optionally be freeze-dried as well prior to insertion in the container where it is then re- hydrated and kept hydrated. An advantage of such optional freeze-drying is that it may reduce the antigenicity of the bone allograft.

Advantages of the present system of bone allograft storage packaging include the elimination of refrigeration requirements, thereby providing allografts which can be quickly prepared for use by a physician when performing a medical procedure. This reduces

the overall cost of system operation as refrigeration equipment is not required, either when storing or transporting the allograft material. A second advantage is that considerable time is not wasted in thawing or re-hydrating the allograft material before transplanting it into a patient.

Preferably as well, the packaging material and the saline solution are sterilized such that the bone allograft can be removed ready for use in a sterilized condition.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a flowchart of a method of packaging a bone allograft for storage to be used in a future medical procedure in accordance with the present invention.

Fig. 2 is a flowchart of a method of preparing a saturated saline solution for use in the method shown in Fig. 1.

Fig. 3 is an illustration of bone allograft material stored in a saline solution in a container in accordance with the present invention.

Figs. 4A and 4B are illustrations of bone allograft material stored in a saline solution in a shape conformable"shrink-wrap"type container in accordance with the present invention.

Figs. 5A and 5B are illustrations of bone allograft material stored in a saline solution in a shape conformable"shrink-wrap"type container in accordance with another method of the present invention.

Like reference numbers and designations in the various drawings indicate like elements.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS Throughout this description, the preferred embodiment and examples shown should be considered as exemplars, rather than as limitations on the present invention.

FIG. 1 is a flowchart of one method 10 of packaging and storing a bone allograft for use in a future medical procedure. In accordance with the present invention, the bone allograft is placed in an airtight container in a saturated saline solution, such that the bone allograft may be removed for use just prior to the medical procedure. In one optional aspect, method 10 includes freeze drying the bone allograft (step 12). Advantageously, freeze drying the bone allograft may reduce antigenicity of the bone allograft. In other preferred aspects of the present invention, however, this freeze drying step (12) is bypassed. A saturated solution is prepared (step 14) to be added into the container (step 18). The addition

of saline solution to the container may be carried out after, before or concurrently with the placement of the bone allograft in the container (step 16). A simple (ie: non-saturated) saline solution may also be used so that step 14 (the preparation of a saturated saline solution) may also be bypassed in some aspects of the invention.

One exemplary method 30 of preparing the saturated solution (step 14) is shown in FIG. 2. (The present invention is not limited to this particular method of preparing a saline solution. Rather, any suitable method of preparing the saline solution is also within the scope of the present invention).

As shown in Fig. 2, calcium may optionally be added to the solution (step 32), phosphate may optionally be added to the solution (step 34), and magnesium may optionally be added to the solution (step 36) until the solution is saturated (step 38). In accordance with the present invention, none, some or all of steps 32,34,36 may be carried out when preparing the saline solution. In addition, the saline solution may optionally be buffered (to have a neutral pH). The solution so prepared (which may comprise a calcium, phosphate, magnesium salt saturated saline solution) is then added to the bone allograft in the container (step 18). In various optional aspects, other minerals or elements may also be added to the solution, advantageously decreasing mineral leaching from the bone allograft during storage in the container.

Optionally, the amount of solution added to the container is just sufficient to keep the bone allograft hydrated. The solution may optionally be a saline solution or a saturated saline solution. In various optional aspects of the invention in which the bone allograft is freeze dried (step 12) prior to being placed in the container, the amount of solution added is preferably just sufficient to re-hydrate the bone allograft and keep the bone allograft hydrated.

In various aspects of the present invention, the container 40 (Fig. 3) in which allograft 42 is stored may be made from glass, plastic, metal foil, or a combination of these or different materials. Container 40 may optionally be sealed with an airtight seal (step 24 in Fig. 1), for example by a lid 44 placed over container 40 (preferably after air is evacuated (step 22) from container 40). After the air has been evacuated from container 40, bone allograft 42 may then be packaged and stored in a saturated solution 46 (prepared as described above) in container 40, which is preferably airtight. Immediately before allograft 42 is required for use, lid 44 is removed from container 40 and allograft material 42 is removed, already being in a hydrated state.

For illustration purposes, allograft 42 is shown submersion in solution 46 in Figs. 3 and 5. It is to be understood that although allograft 42 is submersed in solution 46 in some cases, the present system requires only enough of solution 46 be used to keep allograft 42 hydrated.

Advantageously, due to the saturation of the solution, the amount of materials leaching from bone allograft 42 into solution 46 will be minimal. In addition, the presence of calcium, phosphate, and magnesium salts in solution 46 may encourage re-mineralization of the bone allograft during storage in container 40. Consequently, bone allograft 42 may conceivably be stored for an indefinite period of time prior to use in a medical procedure.

A further advantage of the present packaging/storage system is that the bone allograft need not be kept in a low temperature environment either during storage in the packaging or during transportation to a medical facility. As such, the bone allograft may advantageously be kept at room temperature during both storage and transportation. As explained above, prior to use in a medical procedure, the bone allograft is simply removed (step 26 in Fig. 1) from the sealed container for use in the medical procedure (step 28 in Fig.

1).

In another optional preferred aspect of the invention shown in Figs. 4A and 4B, bone allograft 42 is sealed and packaged in a"shrink-wrap"type of shape-conforming material 50. Conforming material 50 may include foil and plastic. In one approach, bone allograft 42 is placed into conforming material 50, air 51 is removed by tube 53, causing conforming material 50 to become"shrink wrapped"around bone allograft 42 as shown in Fig. 4B. Thereafter, solution 46 is added into the shrink wrapped package of conforming material 50, for example by needle 56 inserted through self-sealing valve 54, thereby keeping allograft material 42 hydrated and readied for immediate or near-immediate use. In this aspect of the invention, the amount of solution added to the packaging is preferably just sufficient to keep the bone allograft hydrated.

Alternatively, as shown in Figs. 5A and SB, bone allograft 42 and solution 46 can be first added together into conforming material 50, which is then shrink fitted over- hydrated allograft 42 by removing air 51 and a portion of solution 46. Specifically, as shown in Fig. 5A, bone allograft 42 is placed into conforming material 50. Thereafter, air 51 is vacuum removed from conforming material 50 such that it wraps tightly around bone allograft 42 as shown in Fig. 5B. In this aspect of the invention, a portion of solution 46 may also be removed from conforming material 50 as air 51 is removed. However, sufficient solution 46 remains within conforming material 50 (and specifically within bone allograft 42)

such that bone allograft 42 remains hydrated, and ready for immediate or near-immediate use.

As shown in Fig. 5A, a suction tube 53 may be used to remove air 51 (and a portion of solution 46). As shown in Fig. 5B, a clamp (or a self-sealing valve) 54 may be used to prevent air from entering the package provided by conforming material 50.

In another optional aspect of the invention, solution 46 may be inserted in container 40 (Fig. 3) by first inserting a hollow needle (not shown) through an optional self sealing valve 47 passing through lid 44 and then injecting the solution through the needle.

While this invention has been described in terms of a best mode for achieving this invention's objectives, it will be appreciated by those skilled in the art that variations may be accomplished in view of these teachings without deviating from the spirit or scope of the present invention.