Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
1999-06-30
2001-07-31
Reip, David O. (Department: 3731)
Surgery
Instruments
Orthopedic instrumentation
C606S080000, C606S084000, C606S099000, C606S102000, C606S207000, C604S060000, C604S218000
Reexamination Certificate
active
06267767
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an instrumentarium and a method for implanting a cruciate ligament replacement in a knee joint.
Operations by which a cruciate ligament replacement is implanted in a knee joint are generally known in the art. Such operations become necessary in cases where the cruciate ligament in the knee is broken or has been heavily damaged in some other way. Today, one preferably uses endogenous materials as cruciate ligament replacements. Especially the patellar tendon or the semitendinosus tendon have proved to be suitable for use as a required cruciate ligament replacement.
2. Related Prior Art
A method and an instrumentarium for restoring the anterior cruciate ligament using one of such tendons as a cruciate ligament replacement has been known from EP-A-0 440 991.
If in the case of this known method the semitendinosus tendon is to be used as a substitute for the cruciate ligament, the tendon is initially removed with the aid of a tendon cutter, and is then cut to different segments or sections. Some of these segments are folded over in the form of a loop so that double sections are obtained. The individual segments and/or the double segments are then once more placed one beside the other, and their ends are connected by suture threads. The tendon bundle so obtained then forms the replacement for the cruciate ligament.
The cruciate ligament replacement is then fixed between the distal end of the femur and the proximal end of the tibia. To this end, one initially drills a through-bore in the proximal end of the tibia, and a blind bore or closed tunnel in the distal end of the femur, whereafter the ends of the cruciate ligament replacement are inserted into, and fixed in, the two bores, respectively.
Fixing the cruciate ligament replacement in the through-bore of the tibia is effected with the aid of a screw, according to EP-A-0 440 991. In contrast, for fixing the cruciate ligament replacement in the blind bore of the femur, it is stretched by means of suture threads, that are guided through a thin drilled passing channel forming an extension of the blind bore, and a button-like plate applied against an outer face of the femur opposite the blind bore.
If the operation has been successful, this purely mechanical method of fixing the cruciate ligament replacement in the two bores is reinforced, in the course of time, by the cruciate ligament replacement taking adhesion to the surrounding bone material. This adhesion then finally guarantees a durable and reliable hold for the cruciate ligament replacement in the knee.
However, it has been found that when implanted by that method the cruciate ligament replacement does not in all cases grow to the surrounding bone material as desired. This may happen in particular when the cruciate ligament replacement is retained too loosely in the receiving bore. For, in this case the cruciate ligament replacement tends to move with every, even very slight, movement of the knee so that an initial adhesion, that may have formed, is easily broken up again. Another, likewise frequently encountered cause for such difficulties lies in the fact that the cruciate ligament replacement as such has too little contact with the surrounding bone material.
This latter situation may arise in particular when the cruciate ligament replacement, as has been mentioned before, consists of segments folded over in the form of a loop. This is so because the maximum bending radii make the end of the cruciate ligament replacement, i.e. the area of the loop, larger than the area immediately beneath the latter. When the loop is then to be introduced into the blind bore of the femur in the usual way, it is the width of the loop that determines the size and/or the diameter of the blind bore. And this in turn leads to the situation that clear spaces remain below the loop between the cruciate ligament replacement and the walls of the blind bore. Due to such clear spaces, there is no contact between the cruciate ligament replacement and the surrounding bone material at these points, whereby any adhesion is rendered difficult or may even be prevented.
It is, therefore, an object of the present invention that the before-mentioned difficulties should be avoided. It is a further object of the invention to provide an instrumentarium for implanting a cruciate ligament replacement in a knee joint.
SUMMARY OF THE INVENTION
This can be achieved simply and very successfully by placing pegs in the clear spaces between the cruciate ligament replacement and the walls of the receiving bore, which pegs on the one hand fix the cruciate ligament replacement in the bore and on the other hand improve, or even establish, the contact between the cruciate ligament replacement and the walls of the bore.
Placing such pegs in a bore, in which a cruciate ligament replacement has been implanted before, requires however a suitable or, optimally, an even customized instrumentarium, as will be easily appreciated in view of the very limited space and restricted accessibility available in a knee joint. However, such an instrumentarium has not been known heretofore in the art, either.
According to the invention, an instrumentarium has an applicator for inserting a peg in a clear space between the cruciate ligament replacement and the wall of the bore, where the applicator comprises a hollow shaft that is open at its distal end and a push-rod guided in the hollow shaft, and where the applicator comprises an operating element by means of which the push-rod can be displaced in the hollow shaft so that a peg, previously introduced into the hollow shaft, can be pushed out through the opening at the distal end of the hollow shaft.
Using such an applicator it is possible to perform the two steps necessary for placing a peg in the described clear space, namely advancing the peg to a position near the clear space and pushing the peg into the clear space, in a controlled and safe way. This applies especially to arthroscopic interventions of the kind usual today in knee operations.
When using the applicator, the peg is initially introduced into the hollow shaft, whereafter the distal end of the hollow shaft is advanced to a position near the clear space in which the peg is to be placed. Only after the opening at the distal end of the hollow shaft has reached a suitable position at or before the clear space will the push rod be advanced in the direction of the distal end through the operating element inside the hollow shaft. This then allows the peg in the hollow shaft to be inserted in a controlled and purposeful way into the clear space between the cruciate ligament replacement and the surrounding wall of the bore.
Moving the peg to a position near the clear space by means of the hollow shaft in which it is received provides the advantage that the peg can be guided safely and purposefully even under the limited space conditions prevailing in the knee joint. By comparison with a pair of forceps, for example, or a similar instrument it is thus ensured that the peg cannot get lost in the knee joint due to inadvertent movements or if the peg should hit a bone.
Further, pushing the peg out of the hollow shaft by means of a push-rod that can be advanced by an operating element, provides the advantage that it is thus possible to exert upon the rear end of the peg, even during its insertion, a desired pressure as necessary to fix the peg as firmly as possible between the cruciate ligament replacement and the walls of the bore.
It is thus possible to position the peg purposefully and in a controlled way, in spite of the restricted place available and the limited accessibility of the respective clear space.
According to one embodiment of the invention, the hollow shaft of the applicator is curved.
This feature provides the advantage that as a result of this arrangement the point of the hollow shaft can be advanced more easily to the bore receiving the cruciate ligament replacement and, thus, to the clear space to be filled. The bore ends at the articular
Sauer Michael
Strobel Michael
Karl Storz GmbH & Co. KG
Reip David O.
St. Onge Steward Johnston & Reens LLC
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