The present invention relates to surgical devices and procedures used in the field of knee surgery, particularly anterolateral reconstruction in combination with reconstruction of the anterior cruciate ligament (ACL) of the knee.
Three situations have been identified that frequently lead to severe anterolateral rotary (ALR) instability in the knee. In such cases, anterolateral reconstruction should be considered in combination with ACL reconstruction. The three situations are: 1) when patients present with a failed isolated ACL reconstruction in which the tunnels, the graft and the rehabilitation all appear to have been properly done; 2) when patients who have had a previous lateral reconstruction in conjunction with an ACL reconstruction are persistently unstable; and 3) when patients have suffered a knee dislocation. Other situations may exist, and should be determined on an individual basis.
Failure to recognize such severe anterolateral rotary instability and to perform the appropriate extra-articular reconstruction is an under-recognized cause of ACL reconstruction failure. Thus, a means for identifying prospective ACL reconstruction failure candidates is needed, for example, a mechanism for assessing lateral rotary instability/stability.
The Lachman's and flexion rotation drawer tests can be used to assist in the diagnoses of severe lateral rotary instability, helping to identify candidates that should be considered for anterolateral reconstruction in combination with the ACL reconstruction. Those patients with positive Lachman's and flexion rotation drawer tests with grades of at least 2+ have proved to be grossly unstable. Once identified, a procedure and/or device for determining and restoring lateral isometry within an acceptable range during ALR reconstruction is needed. Presently, surgeons rely on “free hand” techniques to determine and restore lateral isometry during ALR reconstructions. These “free hand” methods are time consuming and not always accurate. A faster, more reliable and more reproducible method and apparatus for determining and restoring lateral isometry would thus benefit both surgeons and patients.
The present invention as embodied is directed to a surgical device and method of using the surgical device, referred to as an isometer, for restoring rotary and anterior knee stability when used in combination with an intra-articular ACL reconstruction. The isometer eliminates the variables in “free hand” determination and restoration of lateral rotary stability, and also decreases the time needed to determine lateral rotary isometry.
The isometer includes an elongated body with a slider rod that slides horizontally within the body along a longitudinal slot running nearly the length of the rod. A cannulated fixed stylus is attached transversely to the first end of the elongated body and within that cannulated fixed stylus is a fixed-stylus guide pin that slides freely and but that can be fixed using a fixed-stylus set screw. A cannulated movable stylus is attached transversely to the first end of the slider rod, and within that cannulated movable stylus is a movable-stylus guide pin that slides freely within the cannulated movable stylus but that can be fixed using a movable-stylus set screw. There is a pointer encircling the slider rod that slides with the slider rod, but whose position along the slider rod can also be adjusted manually.
In use, the guide pins are directed into the fixed and movable styli, advanced until the tips protrude beyond the fixed and movable stylus ends, and then immobilized within the styli by tightening the set screws. Once immobilized within the fixed and movable styli, the immobilized guide pins are positioned over previously identified lateral reconstruction tunnel sites such that the fixed stylus and guide pin are positioned over a femoral tunnel site and the movable stylus and guide pin are positioned over a tibial tunnel site. Of course, it is understood that the placement site of pin positioning may be reversed, with the immobilized stylus and guide pins being positioned over a femoral tunnel site and the movable stylus and guide pins being positioned over a tibial tunnel site.
The guide pins are next driven into the bone tunnel sites. In another variation, the guide pins may be first driven into the bone tunnel sites, and then the isometer seated on the guide pins. After the pins are inserted into the bone tunnel sites, and the pins are locked into position using a locking mechanism, such as the previously described set screws, the knee is put through a full range of motion by flexing and extending the knee while the isometer position is maintained. During these full range movements, the movement of the pointer in relation to the isometer body is monitored. If movement of the pointer is unacceptably large (greater than 2 mm, 2.5 mm or 3 mm), the fixed, movable, or both guide pins are re-set, re-positioned and re-driven into different pre-identified lateral reconstruction tunnel sites and the movement of the pointer during full range motion is again monitored until the pointer movement is acceptably small. The determination of the maximum distance allowable is surgeon dependent and depends on the patient's anatomy. In ideal or near ideal circumstances the maximum movement would be no greater than 2 mm.
At this time, the set screws for the fixed and movable guide pins within their respective styli are loosened and the isometer is removed leaving the guide pins in place for completion of the reconstructive surgery. Once the isometer, is removed from the guide pins, a cannulated drill can be seated on a guide pin and a femoral tunnel can be drilled. Similarly, the cannulated drill can be seated on the other guide pin and a tibial tunnel can be drilled.
The isometer of the present invention substantially eliminates the guess-work and skill-intensive techniques inherent in “free-hand” isometry determinations during ALR/ACL combination reconstructive knee surgery, and greatly standardizes the process for such determinations.
Referring now to
The slider rod 3 has a first end 18 and second end 19 and a longitudinal slot 20 (see
The cannulated fixed stylus 2 is attached transversely through the first end 16 of the isometer body 4 and has a corresponding fixed-stylus guide pin 8 that slides vertically within the cannulated fixed stylus 2, through the first end 16 of the isometer body 4. A fixed-stylus set screw 7 is attached near the open-end top of the fixed stylus 2 for immobilizing and releasing the fixed-stylus guide pin 8 within the fixed stylus 2.
The cannulated movable stylus 1 is attached transversely through the first end 18 of the slider rod 3 and has a corresponding movable-stylus guide pin 10 that slides vertically within the cannulated movable stylus 1, through the first end 18 of the slider rod 3. A movable-stylus set screw 9 is attached near the open-end top of the movable stylus 1 for immobilizing and releasing the movable-stylus guide pin 10 within the movable stylus 2.
There may also be a cannulated handle 6 attached to the isometer body 4, aligned in such a way that the fixed-stylus guide pin 8 can be directed through the handle cannulation, though the isometer body 4, and through the slider rod 3, and through the fixed stylus 2.
The cannulated elongated body may also have a side window opening 12 for viewing movement of the pointer 5 along the slider rod 3.
During intra-articular ACL reconstruction, first a lateral incision is made through the subcutaneous tissue from the lateral femoral epicondyle to Gerdy's Tubercle. The fascia lata is divided longitudinally. Gerdy's tubercle is identified along with the site just posterior to the insertion of the lateral collateral ligament on the femur as the sites of the reconstruction tunnels as shown in
The placement sites of the stylus and guide pins may be reversed, such that the fixed stylus 2 and its guide pin 8 are positioned over previously identified tibial tunnel sites and the movable stylus 1 and its guide pin 10 are positioned over previously identified femoral tunnel sites.
The guide pins 8 and 10 are then driven into the bone tunnel sites, preferably using a light mallet. The pins are driven preferably to a depth of about ⅛ to ¼ inch. In another embodiment, the pins are first driven into the bone and then the isometer is placed on the pins.
Once pointer movement 5 is acceptably small indicating that isometry has been determined, the set screws 7 and 9 are loosened to release the guide pins 8 and 10 from their corresponding styli 1 and 2, and the isometer is then removed, leaving the guide pins 8 and 10 in place. The femoral pin is drilled through the femoral cortex exiting medially and sufficiently proximal to avoid the femoral tunnel of the previously reconstructed ACL. The tibial pin is advanced distally and medially in order to avoid the tibial tunnel (if present in an accompanying ACL reconstruction) until it exits the skin.
The guide pins are then used to direct placement of the drill, but once the tunnels are created the guide pins are removed and the reconstructive surgery is then completed.
In a different variation of the methodology of using the isometer, guide pins are first inserted into the femur and tibia at the proposed positions of the femoral and tibial tunnel sites. The styli of the isometer are then aligned with and placed over the guide pins and the guide pins are locked in position using a locking mechanism so that the guide pins are firmly held in position during movement of the knee. The knee is then moved through a normal flexion range of motion as described above and the subsequent steps of the methodology are the same.
Referring now to
It should be understood by one of ordinary skill in the art that each stylus, may include a sharp point for insertion into a bone and that the isometer could be used without guide pins. In such an embodiment, the markings made in the bone by the stylus would be used for either subsequent insertion of a guide pin and used in conjunction with a cannulated drill or the markings could be used with a manual or power drill. It should also be understood that the use of guide pins is preferred since guide pins provide additional precision in the positioning of the femoral and tibial tunnels, since the cannulated drill drills at precisely the position of the guide pin whereas a manual drill may walk away from the marking and therefore provide a less precise tunnel location.
The present invention provides both a surgical device and a reproducible and standardized method for determining lateral rotary isometry in combined ALR/ACL reconstruction. The isometer of the present invention also essentially eliminates the technique-intensive and time-consuming problems inherent in “free-hand” determinations of lateral rotary isometry.
Although various exemplary embodiments of the invention have been disclosed, it should be apparent to those skilled in the art that various changes and modifications can be made that will achieve some of the advantages of the invention without departing from the true scope of the invention. These and other obvious modifications are intended to be covered by the appended claims.
The present U.S. patent application claims priority from U.S. provisional patent application, Serial No. 60/569,987, filed on May 11, 2004 entitled “Surgical Device for Anterolateral Reconstruction” which is incorporated by reference herein in its entirety.
Number | Date | Country | |
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60569987 | May 2004 | US |