Trapezoidal bone plugs and method of bone-tendon-bone ACL reconstruction

[0001] This application claims the benefit of U.S. Provisional Application No. 61/165,351 filed on Mar. 31, 2009, the entire disclosure of which is incorporated by reference herein.

[0002] The present invention relates to the field of surgery reconstruction, particularly, to a method and system of implants for filling bone voids during arthroscopic surgery.

[0003] Anterior cruciate ligament (ACL) reconstruction surgeries are well-known in the art. In general, the ACL reconstruction involves drilling a tunnel through the tibia, drilling a closed tunnel (socket) into the femur, inserting a substitute ACL graft (for example, a bone-tendon-bone (BTB) graft) into the tunnels, and securing the graft to the walls of the tibial and femoral tunnels using interference screws or the like.

[0004] In patients who undergo BTB ACL reconstruction, the BTB graft may be harvested directly from the patient (autograft). These patients typically experience some level of post-operative anterior knee pain in the region of the harvest sites (i.e., patella and the tibial tuberosity), as well as some level of pain while kneeling.

[0005] An implant system comprising two implants (one for the patella and one for the tibia) that includes bone void filler material that is preformed into the typical shape of the two bone voids to be filled (harvest sites) is needed. Also needed is a kit with bone void filler materials preformed into the typical shape of the two bone voids (patella void and tibial tuberosity void), the preformed materials being prepackaged into a single package or kit.

[0006] The present invention provides methods, systems and instruments for forming prepackaged, off-the-shelf osteoconductive or osteoinductive synthetic grafts for autograft BTB harvest sites. Preferably, the prepackaged, off-the-shelf synthetic osteoconductive or osteoinductive grafts have a trapezoidal shape that conveniently matches each of the bone block harvest sites (voids). The grafts may be trimmed to fit the voids. The grafts promote bone ingrowth as the bone is fully replaced. The grafts may be pretreated with autologous blood, autologous conditioned plasma and/or bone marrow products.

[0007] The system of the present invention includes two trapezoidal-shaped bone void filler synthetic implants with specified dimensions (i.e., cut to appropriate sizes and lengths) that are manufactured out of an osteoconductive or osteoinductive material that promotes new bone growth and replacement of the implants. The bone void fillers of the present invention may be designed with a predetermined density and porosity, to balance strength and solubility. The two trapezoidal-shaped bone void filler synthetic implants are packaged as a single, prepackaged system or kit. The implants may be provided with ribs and/or protuberances on the sides of the implants, to create some interference fit when inserted (pressed) into place.

[0008] The prepackaged trapezoidal-shaped bone void filler synthetic implants are prepared and inserted into the respective bone voids in the patella and tibia by a specific method. The preparation and insertion method is critical to preserve normal anatomy and prevent implant shifting and dislodging.

[0009] These and other features and advantages of the invention will be more apparent from the following detailed description that is provided in connection with the accompanying drawing and illustrated exemplary embodiments of the invention.

[0018] The present invention provides methods, systems and instruments for forming prepackaged, off-the-shelf synthetic osteoconductive or osteoinductive grafts for autograft BTB harvest sites. Preferably, the prepackaged, off-the-shelf osteoconductive or osteoinductive grafts have a trapezoidal shape that conveniently matches each of the bone block harvest sites (voids). The grafts may be trimmed to fit the voids. The grafts promote bone ingrowth as the bone is fully replaced. The grafts may be pretreated with autologous blood, or autologous conditioned plasma and/or bone marrow products.

[0019] In an exemplary embodiment, the system of the present invention includes two trapezoidal-shaped bone void filler synthetic implants with specified dimensions (i.e., appropriate sizes and lengths) that are manufactured out of an osteoconductive or osteoinductive material that promotes new bone growth and replacement of the implants. These bone void fillers have a predetermined density and porosity, to balance strength and solubility. The two trapezoidal-shaped bone void filler implants are packaged as a single system. The implants may be provided with ribs and/or protuberances on the sides of the implants, to create an interference fit when inserted (pressed) into place.

[0020] The synthetic implants of the present invention are preferably formed of OSferion, which is an osteoconductive bone graft substitute and bone void filler consisting of 100% high purity Beta-tricalcium phophate (β-TCP), sold by Olympus Biomaterial Corporation, 34-3 Hirai, Hinode-machi, Nishitama-gu, Tokyo 190-0182, Japan. OSferion allows for simultaneous controlled absorption and promotion of osteogenesis. OSferion has a micro and macro porous structure that allows for excellent cell communication to promote vascularization, an optimum pore diameter to facilitate cell infiltration, and a compressive force of 15-20 MPs (2900 pounds/inch²).

[0021] The single system, prepackaged two trapezoidal-shaped bone void filler synthetic implants are prepared and inserted into the respective bone voids in the patella and tibia by a specific method. The preparation and insertion method is critical to preserve normal anatomy and prevent implant shifting and dislodging.

[0022] Referring now to the drawings, where like elements are designated by like reference numerals, FIGS. 1-3 illustrate system 100 of the present invention including two trapezoidal-shaped bone void filler implants 50, 60. The trapezoidal-shaped bone void filler implants 50, 60 are provided as a prepackaged, off-the-shelf system (i.e., as a single package or single kit) with each of the filler implants conveniently matching the shape and configuration of the bone block harvest sites (recipient sites or voids) to fill. In the exemplary embodiment shown in FIGS. 1-3, the trapezoidal-shaped bone void filler implant 50 has the shape and configuration of the patellar void to be filled (in the patella 55) and the trapezoidal-shaped bone void filler implant 60 has the shape and configuration of the tibial void to be filled (in the tibia 66).

[0023] The trapezoidal-shaped bone void filler implants 50, 60 are preferably trimmed to fit the recipient sites. One advantage is that the implants 50, 60 promote bone ingrowth as the bone is fully replaced. Preferably, the grafts 50, 60 are pretreated with autologous blood, or autologous conditioned plasma, and/or bone marrow products prior to insertion into the respective sites. Treatment of the implants 50, 60 with autologous blood, or autologous conditioned plasma, and/or bone marrow products is preferably conducted intra-operatively (i.e., subsequent to the removal of the implants from the package and prior to insertion).

[0024] In FIG. 10, the two trapezoidal-shaped bone void filler implants 50, 60 may be packaged in a single kit 90. The implants 50, 60 may also be provided with ribs and/or protuberances 52, 62 on the sides of the implants, to create some interference fit when inserted (pressed) into place.

[0025] An exemplary method of preparation and insertion of the system 100 of the present invention is detailed below with reference to specific steps and shown in FIGS. 4-9:

[0026] After the BTB autograft has been harvested from the patient, the base of each void in the patella and tibia are leveled off using morselized or slivered bone remnants from preparing the BTB graft or similar bone void filler.

[0027] Next, the appropriate sized trapezoidal shaped bone void filler 50, 60 is chosen to fill each bone void.

[0028] The implants 50, 60 are then pretreated or presoaked in autologous blood, or autologous conditioned plasma, or bone marrow aspirate products to enhance healing ability. FIG. 4 shows patellar implant 50 being presoaked in autologous blood 70.

[0029] Next, each trapezoidal shaped bone void filler is trimmed to match the surrounding bony anatomy. FIG. 5 shows patellar implant 50 being trimmed by trimmers 72. The distal portion of the patellar implant 50 is rounded to match the rounded geometry of the distal pole of the patella. This rounding is crucial in maintaining normal anatomy. FIG. 6 shows the rounded portion 52 of the patellar implant 50. In another embodiment the implants are pretreated or presoak after they are trimmed.

[0030] After being trimmed, the patellar implant 50 is inserted into the void in the patellar bone by hand until seated. In another embodiment, the patellar implant 50 is inserted into the void of the patellar bone 55 by an instrument as shown in FIG. 7. The patellar implant 50 is inserted into the patellar bone 55 by passing through opening/defect 80 in patellar tendon 82.

[0031] The tibial implant 60 is also inserted by hand until fully seated in a void in the tibial bone 66. In another embodiment, the tibial implant 60 is inserted into the void of the tibial bone 66 by an instrument. A fully seated tibial implant 60 is shown in FIG. 7. The tibial implant 60 is also inserted by passing through defect 80 in the patellar tendon 82.

[0032] After the implant 50 has been seated an absorbable or nonabsorbable suture 76 is used to close the defect on the proximal side 84 of the patellar tendon 82 at the distal portion of the patellar implant 50 to increase stability of the implant 50 as shown in FIG. 8.

[0033] Next the periosteum and soft tissue are oversewn over the remainder of the visible patellar implant 50 for increased stability as shown in FIG. 9.

[0034] Subsequently, distal portion 86 of the defect 80 of the patella tendon 82 at the proximal end of the tibial implant 60 is closed using an absorbable or nonabsorbable suture 78 to provide stability to the tibial implant 60 as shown in FIG. 9.

[0035] The periosteum and soft tissue are oversewn over the remainder of the visible tibial implant 60 for increased stability as shown in FIG. 9.

[0036] In another embodiment, the patellar implant 50 is set and oversewn before the insertion of the tibial implant 60. In another embodiment, the tibial implant 60 is set and oversewn before the insertion of the patellar implant 50. In another embodiment, both the patellar implant 50 and the tibial implant 60 are set and a single suture is sewn over both the patellar implant 50 and the tibial implant 60 before either the pateller implant 50 or tibial implant 60 is completely oversewn.

[0037] Although the system, kit and method of the present invention have been described above with reference to a specific ACL reconstruction, the system, kit and method of the present invention may also be employed for additional reconstructive procedures, such as tibial plateau fractures and calcaneous fractures, among others.

[0038] Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art.