Knee Retractor

Abstract

This disclosure relates to a surgical retractor for use by an orthopedic surgeon for a controlled distraction of a knee joint through an anterior incision. This retractor generally consists of a pair of screw actuated retractor arms, the tips of which are operatively embedded in the intercondylar region of the patient's knee.

Description

This invention relates to a device useful in orthopaedic surgery, and more particularly relates to a knee retractor which is employed by a surgeon in operating on a patient's knee through an anterior incision, as, for example, to perform a meniscectomy, or for the posterior view of a knee joint to permit the removal of foreign bodies, loose bodies, or the posterior horn of the meniscii.

Operating procedures for performing meniscectomy have not changed in any substantial way for the last 30 years. Current state of the art techniques for doing this kind of an operation call for an anterior incision of some 1-1/2 to 2 inches in length, either anteromedial or anterolateral depending on which side of the knee joint the surgeon intends to do the surgery on. The incision is made and the joint is approached in the usual way employing conventional right-angle retractors to hold the incision open. In performing a meniscectomy, special surgical scalpels are employed to detach the anterior horn of the meniscus and these are then passed around the outer limits of the meniscus detaching it from its margins to the most posterior attachment possible within the limitations of the incision. However, once the detaching reaches approximately ninety degrees around to the side of the joint, the surgeon is frustrated by the extremely tight fibular or tibial collateral ligaments which hold the knee joint closed and laterally intact. Thus, there is no view of the posterior horn of the meniscus, nor is there any way of viewing any loose bodies in the posterior aspect of the joint short of a second posterior incision. Obviously, in order to complete the surgical excision, the surgeon must see what he is doing, since manipulating the scalpel blindly, that is, without a direct visual view, could easily sever any one of several ligaments which hold the knee joint intact, and thus cause severe and permanent patient damage. Accordingly, this problem of non-visibility is currently solved by one of two major methods. First, with the help of one or two surgical assistants, the femur and tibia portions adjacent the knee are manually grasped and forcibly levered so as to cause the knee joint to open laterally, thus providing a direct view of the posterior aspect. This standard surgical procedure is more fully described in Campbell's Operative Orthopaedics, 4th edition, page 798. This is a less than desirable method of operating because of the substantial stress imposed on the convex apex of the levered knee joint. A second method used to approach the posterior aspect of the meniscus is to make a second posterolateral or posteromedial incision. This, of course, prolongs the operation and also complicates it in terms of wound healing. Further, in many cases, it produces a painful posterior incision.

The present invention overcomes these prior art disadvantages by providing a generally bow shaped knee retractor having a pair of screw activated articulating arms in which the terminal tip portions open and close. In the closed position these tips are inserted into the inter-condylar region between the femur and tibia, and then opened so as to forcibly effect a distraction of about one-eighth inch in the knee joint without imposing any harmful stresses thereon. This distraction thus provides an approach to the posterior aspect of the knee joint from an anterior incision.

It is, accordingly, among the various objects of this invention to provide a surgical instrument for distracting the knee joint during a knee operation without imposing harmful stresses on the joint.

It is further an object of this invention to provide a surgical instrument for distracting a knee joint to avoid iatrogenic damage to the joint as a result of blind posterior meniscotom manipulation.

Another object of this invention is to provide a surgical knee retractor instrument for use through an anterior incision thereby providing a direct view of the posterior aspect of the patient's knee joint.

An important feature of this knee retractor is that this single instrument may be employed interchangeably for either an antero-medial or anterolateral approach to either a right knee or a left knee, thus doing away with the necessity of so-called "mirror image" instruments.

A further feature of this invention is that the angular disposition of the retractor arms serves to hold the incision open, thus doing away with the necessity of using a skin, a subcutaneous tissue, and joint capsule right angle retractors, while at the same time performing its primary function of joint distraction.

These and other objects and features will become apparent from the following description when taken in conjunction with the accompanying drawings and photographs in which like numerals refer to like parts in the different views.

FIG. 1 illustrates a front elevation view of the surgical knee retractor;

FIG. 2 illustrates a side elevation view of the knee retractor in FIG. 1;

FIG. 3 illustrates a top plan view of FIG. 1;

FIG. 4 illustrates a bottom plan view of FIG. 1;

FIG. 5 illustrates the knee retractor positioned in the inter-condylar region of a distracted knee joint;

FIG. 6 illustrates a cross-sectioned view of the thrust bearing joint taken on line 6--6 of FIG. 1; and

FIG. 7 illustrates a top plan view taken on line 7--7 of FIG. 1.

Referring now with greater particularity to the drawings, there is shown in FIGS. 1 - 4 the knee retractor 10 fabricated of surgical stainless steel or other suitable material. This knee retractor is generally comprised of two non-planar generally bowered (within included angle A of FIG. 2) retractors arms 11, 12 which are adapted to pivotally open and close by the coaction of a thumbscrew 17 and lever arms 18, 19 and 20, 21, operatively connected therewith. The non-planar bowed shape of the retractor arms is characterized by the lower end portions of arms 11, 12 being outwardly, i.e., angularly, disposed with respect to the upper ends thereof as shown by angle A in FIG. 2. Each of these lower end portions of arms 11, 12 is also inwardly bent or off-set toward each other, as seen in FIG. 1, so as to be substantially justaposed when the retractor is in a normally closed position. As shown in FIGS. 1, 2 and 3 each of the retractor arms 11, 12 is pivotally connected at its upper end thereof by a pin 16 into its respective recess 13, 14 of cross-arm 15. Centrally located through cross-arm 15 between pins 16 is threaded aperture 22 adapted to receive threaded shaft 23 carrying a knurled handle 24 at its upper end, and being rotatably connected at its lower end to an actuating link 25 by a thrust bearing 26.

The thrust bearing connection between threaded shaft 23 and actuating link 25 is shown in enlarged cross-sectional detail in FIG. 6. As shown in this illustration, the end portion of threaded shaft 23 is turned to a stem portion 27 of reduced diameter so as to slip-fit through aperture 28 in link 25. The bottom end of stem portion 27 is internally threaded to receive a typical machine screw 29 which has a screw head 30 broad enough to extend beyond the diameter of steam portion 27 and thus come into bearing relation against the lower surface of stem 27 and preferably just barely spaced apart from the surface of actuating link 25. Interposed between the upper surface of actuating link 25 and the shoulder or end portion of threaded shaft 23 is a thrust bearing 26 comprised of two annular retaining members 31, 32 separated by an annular disc 45 of Delvin or other suitable plastic material having the qualities of lubricity and non-wearing. In view of the structural details of this connection, it can be seen that as threaded shaft 23 is rotated, screw 29 will rotate with it and any relative movement between parts will occur at the thrust bearing and between screw head 30 and actuating link 25.

Actuating link 25 has two recesses at each end thereof 33, 34 and 35, 36 for receiving respectively an end portion of each lever arm 37, 38 and 39, 40 which is pivotally fastened thereto by pins 41. The other end portions of each lever arm are pivotally connected to their respective retractor arm by pins 42.

The lower end portions of retractor arms 11, 12 each have generally beveled surface 43 which carries an outwardly disposed sharpened tip portion 44 of 3 mm in length.

It should now be apparent in light of the foregoing description that as thumb-screw 17 is rotated in a clockwise direction, threaded shaft 23 will advance downwardly through cross-arm 15 exerting a laterally extending force component through each lever arm 37, 38 and 39, 40 to the retractor arms 11, 12 thus causing them to open.

In surgical use, the patient's leg is preferably supported so that the knee is naturally bent at an angular disposition of approximately 45.degree. or more. A conventional incision and approach is made through the subcutaneous tissues and capsule of the knee joint through the synoyium to the joint itself. As shown in FIG. 5, the knee retractor is oriented so that the interior angle A of FIG. 2 faces downward. The tips 44 at the end of the retractor arms are placed deep in the intercondylar notch of the femur 50 well away from any weight bearing surface superiorly and inferiorly into the anterior aspect of the anterior cruciate ligament 49 also a non-weight bearing portion of the tibia 51. Once the retractor tips are in position, thumb-screw 17 may be rotated thus spreading retractor arms 11, 12 apart with a force sufficient to overcome the ligament forces tending to keep the knee joint in its naturally approximated position, i.e., the tibia against the femur. The tips 44 are designed with a generally sharpened conical shape for the obvious reason of preventing any slippage. Though, as can be seen from FIG. 6, these tips presumably indent the cartilage in their respective areas of contact, they do not disrupt in any way the weight bearing surface gliding features of the knee joint. Distraction is carried out as far as possible until there is sufficient resistance so that the retractor will open no further. This will usually open the side of the knee joint being operated on approximately one-eighth of an inch. This, of course, depends on the health of the knee's collateral ligaments and in the usual young knee, about one-eighth of an inch is the maximum opening. This small distraction, however, is the crucial contribution of this instrument. However, in a knee where collateral ligaments have been destroyed, as, for example, in the injury O'Donahue's Triad, where the medial collateral ligament, medial meniscus, and the anterior cruciate ligament have all been torn, distraction of the knee is possible up to one-half inch, and beyond that, distraction is not necessary.

Use of the herein disclosed knee retractor results in an average reduction in operating time of 25 percent since no extraordinary surgical maneuvers are necessary to achieve opening of the posterior aspect of the joint in order to assure removal of the entire meniscus. A further desirable feature of this knee retractor, particularly from a cosmetic point of view, is that its use allows a minimal skin incision anteriorly only, and with the reduced morbidity in wound healing, recovery time is substantially reduced with limited ambulation occurring in normal cases within 3 days.

Thus, it should now be apparent in light of the foregoing disclosure that as a result of the generally bowed shape, seen in FIG. 2, coupled with the retractor arm off-set portions, shown in FIG. 1, I have provided a useful surgical instrument which provides means for a controlled knee joint distraction heretofore unavailable.

The particular embodiment of the invention herein chosen for illustration and description is exemplary only and it will, accordingly, be understood that various changes in the details, materials and arrangement of parts herein described and illustrated may be made by those skilled in the art within the principles and scope of the invention as expressed in the appended claims.

Claims

Having thus described my invention, I claim:

1. A surgical retractor for use in knee joint distraction comprising:

a. a cross-arm member;

b. a pair of non-planar generally bow-shaped retractor arms each pivotally connected at its upper end thereof to a respective end of said cross-arm member;

c. the lower end of each retractor arm having an elongated off-set portion which is angularly outwardly disposed in a laterally extending plane with respect to the upper end thereof, and generally parallel to each other, each off-set portion being juxtaposed the other in the normally closed retractor position; and

d. actuating means operatively connected to said retractor arms for opening and closing them.

2. The retractor set forth in claim 1 wherein each said off-set portion carries adjacent its lower end a sharpened tip extending outwardly in opposed relation to one another in a direction substantially colinear with the travel of the retractor arms, as they are opened, and adapted for insertion into the intercondylar notch of the femur in the knee joint being distracted.

3. The retractor set forth in claim 2 wherein said actuating means comprises;

a. screw means operatively carried by said cross-arm;

b. an actuating link supported on the end of said screw means; and

c. laterally extendable lever arm members pivotally connecting said actuating link with said retractor arms.

4. The retractor set forth in claim 3 wherein said screw means comprises;

a. a threaded shaft; and

b. a thrust bearing interposed between the end of said threaded shaft and the actuating link.