Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
1998-04-03
2001-10-02
Recla, Henry J. (Department: 3731)
Surgery
Instruments
Orthopedic instrumentation
C606S213000
Reexamination Certificate
active
06296641
ABSTRACT:
BRIEF DESCRIPTION OF THE INVENTION
This invention relates in general to a bioabsorbable surgical tissue fixation implant (nail) and, more particularly to an implant for the fixation of soft tissue to bone.
In such procedures as rotator cuff surgery or labrum rupture fixation surgery and hand tendon surgery, tendons or other soft tissues are fixed to bone. The tendons or other tissue are often secured to bone by feeding the soft tissue through holes formed in the bone and suturing the tissue in place. Another method of securing soft tissue to bone employs a fixation device which essentially tacks the tendon to bone. Unless the tendon or other soft tissue is completely immobilized, the fixation device must be securely embedded in the bone to hold the tendon or other soft tissue stationary against the bone surface, resisting those forces tending to pull the tendon or soft tissue away from the bone surface, until the tendon or soft tissue has become attached to the bone. Another method of securing tendon and other soft tissue to bone uses a fixation device (suture anchor) with an attached suture. Once again, the fixation device must be securely embedded in bone to resist forces tending to pull the tissue away from the bone surface.
Bioabsorbable soft-tissue fixation devices are frequently used, because they biodegrade after the tissue has healed and therefore do not cause long-term problems in the tissue and do not require a removal operation.
However, the presently known bioabsorbable fixation implants for attaching soft tissue to bone have encountered several problems in clinical use, especially in rotator cuff or labrum rupture fixation. According to references E. E. Berg and W. Oglesby, J. Shoulder & Elbow Surg. 5, pp. 76-78 (1996) and P. Kavli et al. Acta Orthop. Scand. 272, p. 24 (1996), the entire disclosures of which are incorporated herein by reference, the use of bioabsorbable tacks and staples in the surgical fixation of shoulder instability led to recurrent instability or loosening, causing healing problems. Bioabsorbable nails or bolt-type tacks, which are stronger than staples, have symmetrical heads that are anatomically unsuitable to labrum or rotator cuff fixation as can be seen from schematic FIG.
1
. The symmetrical head of the tack does not mate effectively with the bone surface because the angle between the tack head and the shaft is 90 degrees, while the angle between the bone surface and the shaft is less than 90 degrees. Additionally, that part of the symmetric head (on the right side of the shaft in
FIG. 1
) which does not bind the soft tissue, is unnecessary for healing and can irritate the rim of the joint cavity.
U.S. Pat. No. 5,634,926, the entire disclosure of which is incorporated herein by reference, describes a bone or soft tissue fixation implant having a leg (shaft) portion and an enlarged end (head) portion arranged so that the longitudinal axis of leg portion being oriented at an angle of 15 to 55 degrees relative to the mating surface of the enlarged end. However, this implant is expressly restricted to those applications where no forces will be exerted on the implant that will tend to pull it out of the bone. This implant does not effectively grip the drill hole in the bone to resist tensile forces, because the leg portion is constructed so that it is easily pulled in a direction parallel to the longitudinal axis of said hole. Therefore, the high muscular forces which load the labrum or rotator cuff during healing would pull the leg portion at least partially from the drill hole during healing, causing severe complications.
Another problematic feature of the implant of U.S. Pat. No. 5,634,926 is that the enlarged end, even if non-symmetrical, still projects in all directions from the leg portion. Thus, the portion of the end that is directed to the rim of the joint cavity in labrum or rotator cuff fixation is ineffective and unnecessary for soft tissue fixation and can cause irritation to the rim of the joint cavity.
Accordingly, there is a need for a bioabsorbable fixation implant that is capable of securely and effectively affixing ruptured rotator cuff or labrum tissue to the bone and/or cartilage surface and is designed to optimize fixation capacity and to avoid unnecessary mass and mechanical irritations of shoulder joint tissues.
OBJECTS AND SUMMARY OF THE INVENTION
It is a primary object of this invention to provide a fixation implant for the effective surgical fixation of soft tissue or tendon tissue to bone.
It is another object of this invention to provide a fixation implant for the fixation of rotator cuff or labrum tissue to bone and/or cartilage surface in which the size of the fixation implant is minimized.
It is further an object of this invention to provide a fixation implant which may be fabricated of materials which are absorbed by the body over time.
It is further an object of this invention to provide a fixation implant which may be economically manufactured and which may be efficiently and reliably employed in the fixation of soft tissue to bone.
In summary, this invention provides a fixation implant that is particularly suitable for use in the fixation of soft tissue to bone. In one embodiment of the invention, the fixation implant generally includes at least one shaft configured to securely fit into a hole formed in bone. The shaft is of sufficient length relative to the interior diameter of the hole and, in some preferred embodiments, has locking protuberances, like threads, ridges, or barbs, that resist removal of the shaft from the hole in the bone when different types of forces, such as tensile or bending forces, are applied to the implant. The shaft is generally cylindrical in shape, however, in various embodiments of the invention, different cross-sections could be used. In a preferred embodiment of the present invention, the implant has a flattened and bent end portion emerging from only one side of the shaft. At the other side of the implant the outer surface of the shaft and the emerging end portion form a smooth surface, without any projections. This smooth surface at the end of the implant prevents irritation of the surrounding tissue. The end portion has a mating surface configured to grip a portion of the soft tissue surrounding the hole between the bone and the mating surface. The longitudinal axis of the shaft is oriented at an angle of less than 90 degrees relative to the mating surface. In this fashion, the implant anchors soft tissue, such as rotator cuff tissue, to bone.
Additional objects and features of the invention will be more readily apparent from the following detailed description and appended claims when taken in conjunction with the drawings.
REFERENCES:
patent: 4503847 (1985-03-01), Mouradian
patent: 5246441 (1993-09-01), Ross et al.
patent: 5259398 (1993-11-01), Vrespa
patent: 5454814 (1995-10-01), Comte
patent: 5601558 (1997-02-01), Torrie et al.
patent: 5634926 (1997-06-01), Jobe
patent: 5843084 (1998-12-01), Hart et al.
patent: 5941881 (1999-08-01), Barnes
patent: 6015410 (2000-01-01), Tormala et al.
Burkhead W.
Happonen Harri
Helevirta Pertti
Kaikkonen Auvo
Pohjonen Timo
Bionx Implants Oy
Kenyon & Kenyon
Ngo Lien
Recla Henry J.
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