Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Ligament or tendon
Reexamination Certificate
2002-10-23
2004-05-04
McDermott, Corrine (Department: 3733)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Ligament or tendon
C623S017160
Reexamination Certificate
active
06730124
ABSTRACT:
FIELD OF INVENTION
The present invention is generally directed toward a surgical implant product and more specifically is a shaped allograft cancerous bone block implant assembly.
BACKGROUND OF THE INVENTION
Failed ligaments, such as the anterior or posterior cruciate ligaments in the knee joint, significantly limit physical activity and potentially cause chronic knee problems. The anterior cruciate ligament (hereinafter ACL) and the posterior cruciate ligament (PCL) to a lesser extent are often torn during sports related injuries or as result of traumatic stresses. Ligament reconstruction with allograft and autograft tissue has been shown to improve joint function and provide long term improvement in restoration of physical activity. A common surgical method of repair of an ACL is harvesting a patient's patellar tendon with bone blocks from the tibia and patella. The bone-patellar tendon-bone implant offers several advantages, including high initial tensile strength, stiffness, proper length, rigid fixation and direct bone-to-bone incorporation.
The ACL of the knee functions to resist anterior displacement of the tibia from the femur at all flexion positions. The ACL also resists hyper-extension and contributes to rotational stability of the fully extended knee during internal and external tibial rotation. The ACL may also play a role in proprioception. Structurally, the ACL attaches to a depression in the front of the intercondylar eminence of the tibia extending poster-superiorly to the medial wall of the lateral femoral condyle.
Partial or complete tears of the ACL are very common, comprising about 100,000 outpatient procedures in the U.S. each year. The preferred treatment of the torn ACL is ligament reconstruction, using a bone-ligament-bone autograft. Cruciate ligament reconstruction has the advantage of immediate stability and a potential for immediate vigorous rehabilitation. However, the disadvantages to ACL reconstruction are significant: for example, normal anatomy is disrupted when the patellar tendon or hamstring tendons of the patient are used for the reconstruction; placement of intraarticular hardware is required for ligament fixation; and anterior knee pain frequently occurs. Moreover, recent reviews of cruciate ligament reconstruction indicate an increased risk of degenerative arthritis with intraarticular ACL reconstruction in large groups of patients.
A second method of treating ACL injuries, referred to as “primary repair”, involves suturing the torn structure back into place. Primary ACL repair has the potential advantages of a limited arthroscopic approach, minimal disruption of normal anatomy, and an out-patient procedure under a local anesthetic. The potential disadvantage of primary cruciate ligament repair is the perception that over the long term, ACL repairs do not provide stability in a sufficient number of patients, and that subsequent reconstruction may be required at a later date. The success rate of such anterior cruciate ligament repair has generally hovered in the 60% to 70% range.
The autogenous patellar tendon is an excellent tendon replacement source, providing proper tendon length and bone blocks that are fully osteointegrated without immunological rejection. Unfortunately harvesting autogenous bone-tendon-bone (hereinafter B-T-B) also has a number of adverse effects, including donor morbidity (pain), patellar fracture, tendon rupture and degeneration of the patellofemoral articular surface. As an alternate to autogenous graft tissue, synthetic materials have previously received FDA approval. In this regard polyester braids, steel wire and PTFE (GORE-TEX) have been used surgically. All of these materials have failed to integrate into the bone resulting in the tendon's inability to sustain the tensile and torsional loads applied to the knee in normal usage. Nearly all of these synthetic repairs have been revised with autogenous and/or allograft tissue.
There is a limited supply of allograft bone-patellar tendon-bone (B-PT-B) tissue due in large part to the number of donors that qualify according to the selective donor acceptance criteria. As a result of the limited number of available grafts there is a demand for such grafts which exceeds supply.
The use of substitute bone tissue dates back around 1800. Since that time research efforts have been undertaken toward the use of materials which are close to bone in composition to facilitate integration of bone grafts. Development has taken place in the use of grafts of a mineral nature such as corals, hydroxyapatites, ceramics or synthetic materials such as biodegradable polymer materials. Surgical implants should be designed to be biocompatible in order to successfully perform their intended function. Biocompatibility may be defined as the characteristic of an implant acting in such a way as to allow its therapeutic function to be manifested without secondary adverse affects such as toxicity, foreign body reaction or cellular disruption.
Human allograft tissue is widely used in orthopaedic, neuro-, maxillofacial, podiatric and dental surgery. The tissue is valuable because it is strong, biointegrates in time with the recipient patient's tissue and can be shaped either by the surgeon to fit the specific surgical defect or shaped commercially in a manufacturing environment. Contrasted to most synthetic absorbable or nonabsorbable polymers or metals, allograft tissue is biocompatible and integrates with the surrounding tissues. Allograft bone occurs in two basic forms; cancerous and cortical. Cancellous bone is a less dense structure than that of cortical bone and is also comprised of triple helix strands of collagen fiber, reinforced with hydroxyapatite. The cancellous bone includes void areas with the collagen fiber component contributing in part to torsional and tensile strength.
Many devices of varying shapes and forms are fabricated from allograft cortical tissue by machining. Surgical implants such as pins, rods, screws, anchors, plates, intervertebral spacers and the like have been made and used successfully in human surgery. These pre-engineered shapes are used by the surgeon in surgery to restore defects in bone to the bone's original anatomical shape. At the present time cancellous bone has not been commercially used for shaped devices which are subject to pull out forces.
Allograft bone is a logical substitute for autologous bone. It is readily available and precludes the surgical complications and patient morbidity associated with obtaining autologous bone as noted above. Allograft bone is essentially a collagen fiber reinforced hydroxyapatite matrix containing active bone morphogenic proteins (BMP) and can be provided in a sterile form. The demineralized form of allograft bone is naturally both osteoinductive and osteoconductive. The demineralized allograft bone tissue is fully incorporated in the patient's tissue by a well established biological mechanism. It has been used for many years in bone surgery to fill the osseous defects previously discussed.
U.S. Pat. No. 5,972,368 issued on Oct. 26, 1999 discloses the use of cortical constructs (e.g. a cortical dowel for spinal fusion) which are cleaned to remove all of the cellular material, fat, free collagen and non-collagenous protein leaving structural or bound collagen which is associated with bone mineral to form the trabecular struts of bone. The shaped bone is processed to remove associated non-collagenous bone proteins while maintaining native bound collagen materials and naturally associated bone minerals. The surface of a machined cortical bone surface is characterized by a wide variety of openings resulting from exposure by the machining process of the Haversian canals present throughout cortical bone. These canals serve to transport fluids throughout the bone to facilitate the biochemical processes occurring within the bone. They occur at variable angles and depths within the bone.
In French Patent Applications Nos. 2,582,517 and 2,582,518 fragments of bones taken from animals, primarily cattle w
Gipple & Hale
Hale John S.
McDermott Corrine
Musculoskeletal Transplant Foundation
Phan Hieu
LandOfFree
Bone-tendon-bone assembly with cancellous allograft bone block does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Bone-tendon-bone assembly with cancellous allograft bone block, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bone-tendon-bone assembly with cancellous allograft bone block will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3203370