Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2001-05-17
2002-05-21
Philogene, Pedro (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
C606S131000, C606S082000
Reexamination Certificate
active
06391031
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in the methods used to perform chevron osteotomy procedures that are commonly employed in bunion correction surgery. More specifically, to the design of a device that will aid orthopedic surgeons in making the precise bone cuts that are necessary for the successful completion of a biplane chevron osteotomy procedure and the treatment of a hallux valgus or bunion deformities.
A hallux valgus deformity is a very common foot disorder that results in the formation of a bunion on a patient's foot which can be a source of pain and embarrassment. The deformity is a result of a static subluxation of the first metatarsalphalangeal joint (herein after referred to as the MTP joint) with a lateral deviation of the big toe and a medial deviation of the first metatarsal. More specifically, the word hallux is the medical term for the big toe and valgus is an anatomical term which refers to a deformity that is oriented in a direction away from the midline of the body. That is to say, the term hallux valgus describes a big toe that, from its tip to its base, is deformed in an outward manner in relation to the body of the foot. The condition can also be medically described in terms of the first metatarsal bone as metatarsus primus varus which refers to the orientation of the first metatarsal from its tip to its base being pointed towards the midline of the foot.
The result of this skeletal deformity is very often a large protruding bump on the outside base of the big toe that can be very sensitive to any pressure created by contact. Additionally, the condition is self-perpetuating in that the pressure it creates against the patient's footwear causes the metatarsal bone at the point of contact to thicken. This thickening at the head of the metatarsal increases the size of the resulting bunion which adds to the pressure at the point of contact which in turn increases the severity of the condition and the associated discomfort to the patient.
The most common cause of a hallux valgus condition is the prolonged deformity of a foot which is most commonly associated with the long term wearing of improperly fitting footwear coupled with some sort of preexisting susceptibility resulting from such things as genetic factors or prior trauma. The footwear connection to the disorder is supported by the fact that it is much more common in women who are prone to wearing high heel shoes having a constricted forefoot area. This tends to force the big toe into an abnormal position which can cause the associated muscles to migrate laterally. Once this migration of the muscles passes outside of the line of the MTP joint the resulting hallux valgus condition tends to reenforce itself and continually worsen.
The first step taken in the medical diagnosis and treatment of a hallux valgus condition is to accurately define a number of critical measurements through the use of a series of X-rays taken of the foot's bone structure. One of these is the intermetatarsal angle (herein after referred to as the IM angle) which is defined by the relationship of the first metatarsal shaft compared to the line of the second metatarsal shaft and generally in normal circumstances is between 6 and 9 degrees of deviation.
Another of the measurements taken is the determination of the hallux valgus angle (herein after referred to as the HV angle) which defines the angle of the line created at the MTP joint between the first metatarsal bone shaft and the first phalangeal bone shaft. This angle is generally considered to be within the normal range at 9 to 10 degrees and any HV angle that measures greater than 12 degrees is considered to be in the abnormal range requiring some sort of corrective action to be taken. Additionally, the distal metatarsal articular angle (herein after referred to as the DMAA) can also be measured which quantifies the angle created between the line if the first metatarsal shaft and the metatarsal head's contact surface at the MTP joint.
Finally, the preliminary examination will also include an evaluation of the condition of the MTP joint to determine whether there has been a lateral subluxation of the joint. The combined evaluation of these and other factors will determine the course of action to be taken and in general terms a patient with a congruent MTP joint (a joint with no lateral subluxation), an IM angle of less than 15 degrees, and a HV angle of less than 30 degrees is a candidate for chevron osteotomy corrective surgery. For those patients who's hallux valgus condition does not fall within these parameters there are other corrective procedures available.
The chevron osteotomy procedure for the correction of a hallux valgus condition has been around for a long time so it is quite natural that there exists numerous devices that are intended to aid a surgeon in the performance of a chevron osteotomy. An example of this type of device is illustrated in U.S. Pat. No. 5,843,085 issued to Graser 1998. The Graser patent describes a device which is intended to be used as a cutting guide in three different types of osteotomy procedures and consists of a two piece jig having multiple cutting slots and which may also require the use of more than one KIRSCHNER wire. While the device performs its desired functions, the fact that it is designed to perform multiple functions means that it is inherently complex and cumbersome to use which increases the risks of error when compared to a hypothetical design for a single use device.
Therefor, from the forgoing discussion it can be seen that it would be desirable to provide a device that would aid a surgeon in performing a biplane chevron osteotomy procedure for the correction of a hallux valgus condition. Additionally, that it would be advantageous to provide such a device that would be simple to use and that would allow the surgeon to make the complex bone cuts involved time after time with a high degree of accuracy.
SUMMARY OF THE INVENTION
It is the primary objective of the present invention to provide a means by which a surgeon can use a device that will aid him in making the V-shaped biplane cuts in the first metatarsal bone of a human foot that are necessary to perform a biplane chevron osteotomy procedure to correct a hallux valgus or bunion deformity.
It is an additional objective of the present invention to provide such a device that will allow a surgeon to precisely mark the forward end of the first metatarsal bone in such a manner that will provide a clear guide in making the subsequent primary superior and inferior osteotomy cuts through the stem of the first metatarsal.
It is an additional object of the present invention to provide such a device that will allow for the making of such cuts in the precise location on the metatarsal that is desired and also at the exact 67 degree angle, or formed so as to measure any other angle as desired in the procedure between the superior and inferior components of the primary osteotomy cut in the chevron procedure.
It is an additional objective of the present invention to provide such a device in which the initial marking portion (the primary guide body) is designed in such a way that the forward marking portion will slip into the primary superior and inferior cuts allowing the most forward surface of the secondary guide body to fit tightly against the distal surface of the capital fragment of the metatarsal.
It is a further objective of the present invention to provide such a device that has a secondary guide body formed in a such a manner so that its sides are precisely angled to provide the surgeon with guiding surfaces to aid in the making of the secondary superior and inferior cuts necessary to complete the bone cutting stages of the biplane chevron osteotomy.
It is a still further objective of the present invention to provide such a device to aid a surgeon in the performance of a biplane chevron osteotomy that can be easily manufactured in an inexpensive manner which will facilitate its wide distribution and thus impro
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