GB2068139A - Endoscope - Google Patents

Abstract

The cross-section of an endoscope (arthroscope) for inspection of or operation on bone joints is approximately rectangular and of a width along the inner axis 20 sufficient to accommodate the largest of the three components which comprise an objective lens 11, an irrigation conduit 12 and an instrument channel 13. These components are enclosed by a steel sheath 14 and the spaces are filled with optical fibres 15 for illumination. Opposite faces of the sheath are preferably curved in the same sense to a radius of between 2 and 3 cm to fit more readily into the gaps between bones in the principal joints, such as the knee, shoulder, and hip joints. <IMAGE>

Description

SPECIFICATION Endoscope This invention pertains to endoscopes in general and to arthroscopes in particular. Specifically, it provides an endoscope in a configuration ideal for use in arthroscopy.

Endoscopy is the art of examining the interior of a body cavity or hollow organ by the use of a slender tubular telescopic instrument called an "endoscope". Endoscopes have been in common use since the early twentieth century. These instruments include a lens system, which may be conventional glass lenses within a rigid tube, air spaces between glass rods shaped to configurate the entrapped air pockets as lenses, optical glass fibres combined with conventional lenses, or other means; and a lighting system, which may be a direct illumination system (e.g., a tungsten light bulb) but is more often fibre light (light transferred from an external source through optical glass fibres). Endoscopes also commonly contain an irrigation system for introducing fluids, typically normal saline solution, to the region being examined.These systems are all contained within a cylindrical tubular housing, usually called a "sheath", which may be flexible, but is more often rigid. The cross-sectional configuration of the sheath normal to its longitudinal axis (that is, as viewed from the distal end of the endoscope) is tranditionally circular.

Examples of modern endoscopes are disclosed in U.S. Patents Nos. 3,525,332; 3,599,630; 3,608,547; 3,730,632; 3,744,906; 3,818,902; 3,819,267; and 3,889,662.

Endoscopes have been used for arthroscopic examinations for several decades. The development of arthroscopy and instruments adopted for arthroscopic examinations (arthroscopes) is described in the monograph "Arthroscopy of the Knee", Robert W. Jackson and David J. Dandy, Modern Orthopedic Monographs, 1976 Grune 8 Stratton, Inc., New York. From the monograph, it is apparent that the principal objective sought in developing arthroscopes has been to reduce their diameter compared to earlier endoscopes. All of the components conventional to an endoscope, namely an optical system, a lighting system, an irrigation system, and often an instrument channel, are contained within a usually rigid cylindrical sheath of approximately circular cross-section.The Watanabe 22 shown in Figs. 2 to 5 of the monograph utilizes a sheath slightly oval in cross-section to accommodate two crescentic bundles of light fibres for illumination. The grouping of the light fibres in this fashion is to avoid the penumbra typically present in the centre of the visual field.

Examination of the knee joint, or other joints, imposes certain restrictions on procedures not normally encountered with other endoscopic examinations. For example, a persistent problem in arthroscopy has been maintaining adequate sterility. A circular crosssection is appropriate for introduction into the orifices of the genitourinary and gastointestinal tracts or for puncturing the abdominal wall, but the introduction of conventional round arthroscopes to the knee joint tends to be traumatic because of the limited spacing between bones. Conventional arthroscopes of small cross-section are susceptible of breakage if the knee is flexed or if too much force is applied in efforts to distract the joint using the arthroscope as a lever or fulcrum. In the past, less delicate arthroscopes have necessarily been constructed within sheaths of greater diameter.

The arthroscope of this invention departs substantially from the structural concepts traditional to endoscopes. The instrument provides the necessary components for examination (lens system, light system and usually an irrigation system) within a sheath housing having a cross-sectional configuration (take normal the major axis of the arthroscope) which is neither circular nor oval, but is shaped as either a parallelogram or a modified parallelogram with a pair of approximately parallel longer sides and a pair of shorter sides which may also, but need not be parallel. The aforedescribed cross-sectional configuration is perceived by viewing the arthroscope from its distal end.Of substantial importance is that the spacing between the longer sides (referred to as the "thickness" of the instrument) be as small as possible, having due regard to the space requirements of the components within the sheath. In a diagnostic arthrosope, the component of largest diameter is usually the lens system. The cross-sectional spacing between the longest sides of the sheath need than be just sufficient to accommodate this component. Operating arthroscopes sometimes require larger sheaths to accommodate an instrument channel of greater diameter than the lens system.

The longer sides, while generally parallel or approximately parallel, are desirably arcuate with a radius of curvature selected to approximately match the bones of the joint undergoing examination. In most instances, when the longer sides are arcuate, one side wall is concave and the other is convex, although it is possible for those side walls to be either mutually concave or convex. The radius of curvature selected will necessarily vary accord- ing to the construction of the joint of interest, size of the individual patient, and other factors. In practice, however, a radius of curvature between about two and about three centimetres is generally appropriate for large joints such as the knee, hip and shoulder joints. A radius of about 2-1/2 centimetres is presently regarded as ideal for an instrument intended for general purpose applications.

Although the instruments of this invention are purposely constructed as thin as possible, the spacing between the short sides of the cross-section, (referred to as the "width" of the instrument) may be relatively large. That is, considerable freedom of width is permissi ble to accommodate a number of structural features not available with conventional arthroscopes. By way of illustration, the width of the instrument may be enlarged to accom modate additional optic fibres, if greater bril liance at the operational site is desired. This feature has application in instruments adapted for photography or to incorporate teaching attachments, for example. For most applications, adequate lighting is provided when the cross-sectional area of the optic fibres in the sheath approximately equals the cross-sectional area of the objective lens.Freedom of width also permits adaption of the distal end of the arthroscope as a retractor to move the synovium or the fat pad aside. Moreover, the instrument channel may be shaped to pass relatively wide instruments, thereby obviating one of the limitations heretofore imposed on the design of surgical instruments used with arthroscopes.

One of the inherent difficulties of mastering arthroscopic techniques has been the lack of depth perception provided by conventional arthroscopes. The increased width permitted by the present invention offers two means for improving on this situation. First, depth perception and persepctive at the operative site is enhanced by increasing the lateral spacing of the objective lens from the distal termination of the instrument channel. The surgeon thus observes the instrument approaching the operative site at an angle rather than directly in his line of sight. Second, it is within contemplation to mount a second lens system within the sheath, thereby providing true binocular vision. Either or both of these expedients will enable many more surgeons to become skillful at arthroscopic surgery, and should also permit the development of more intricate diagnostic and surgical procedures.

Of paramount importance, the "thinness" of the arthroscopes of this invention permits more thorough examination of joints with greater accuracy. The potential for false negative readings is greatly reduced. (A "nega- tive" reading means that nothing wrong is observed). When the arcuate shape hereinbefore described is incorporated, both diagnostic and surgical procedures are further facilitated.

The claimed arthroscopes often can probe to the interior of a joint without mechanically districating the joint as in current practice.

The aforedescribed advantages are achieved with an attendant reduction of trauma to the patient. First, the soft tissues which must be penetrated to gain access to the joint space suffer markedly reduced trauma through use of this invention. Of even greater significance, from the standpoint of present experience in the art, the present invention causes less ) trauma to the cartilage surface of the joint. In those instances when the tip of the arthros cope is used as a fulcrum, e.g., to pry open the back of a knee joint, the forces are spread over a larger surface area, thereby avoiding ; damage both to the cartilage and the instru ment. The sheath of the claimed arthroscopes may be thicker than is now conventional.

Moreover, it is practical to contour and polish the sheath exterior to avoid laceration of the ) cartilage surfaces.

In the drawings, which illustrate what is presently regarded as the best mode for carry ing out the invention: Figure 1 is a typical operating arthroscope of this invention viewed from its distal end and showing the arrangement of its compo nents; Figure 2 is a similar view of a typical diagnostic arthroscope of this invention; Figure 3 is a similar view of the arthroscope of Fig. 1 together with a series of prior art instruments drawn to the same scale; Figures 4 to 6 illustrate various joints with an arthroscope of this invention in place; and Figure 7 is a binocular version of an operat ing arthroscope of this invention viewed from its distal end.

The operating arthroscope illustrated by Fig.

1 comprises a lens system, the objective lens 11 of which is visible from the distal end of the instrument; an irrigation system, including the conduit 12; and an instrument channel 13; arranged within a rigid sheath 14. The interstitial spaces between the components 11,12 and 13 and within the sheath 14 are packed with light-transmitting optic fibres 15.

The arthroscope of Fig. 1 is constructed in generally conventional fashion except for the cross-sectional shape of the sheath 14 and the arrangement of the components 11, 12, 13 and 15 housed within the sheath 14. As viewed from its distal end, the cross-section of the arthroscope may be considered as having a minor axis, represented by line 20, which intersects its geometric centre 21; and a ma jor axis, represented by the line 22, normal the minor axis 21 at the centre 21. The distal ends of instruments with regular cross-sec tions will be bisected into two congruent parts by the minor axis 20 as shown.

The sheath 14 is of rigid, e.g., stainless steel, construction, and includes two relatively long side walls 31, 32 and two relatively short side walls 33, 34. The side walls 31, i 32 which intersect the minor axis 20 are approximately parallel. Ideally, these side walls 31,32 are arcuate, as shown, to approx imately match the surface contours of the bones in a joint. In the illustrated instance, the radius of curvature R is approximately 2.5 centimetres, side wall 31 is concave and side wall 32 is convex.The short side walls 33, 34 may also be approximately parallel, as shown, and are ideally as short as possible; usually just long enough to provide the minimum spacing required between the side walls 31 and 32 to contain the largest system housed in the sheath 14(instrument channel 13, Fig. 1; or the lens system 41, Fig. 2).

The width (that is, the spacing of the side walls 33 and 34), of the instrument is selected to provide adequate cross-sectional area for the irrigation system (water channels 12, Fig. 1 and 42, Fig. 2) desired; the lighting system (optical fibres 15, Fig. 1 and 45, Fig.

2); and any other systems which may be included within the sheath.

For applications requiring greater strength, the corners 50 connecting side walls, e.g., 32 and 33, may be structurally reinforced e.g., by thickening the sheath as shown 51. The lenses 11, 41 are show contained within rigid tubes 50, e.g., of structural plastic or metal.

The various channels 12, 13, 42 are typically defined by similar rigid tubes or conduit 51.

Example I The operating arthroscope illustrated by Fig.

1 may be constructed within a sheath 14 measuring about 3-1/2 by about 7 millimetres in cross-section to house a lens system within a 2.5 mm objective lens 11, a 3 mm instrument channel 13, a generous water channel 12, and ample optical fibres 15.

Example I! The diagnostic instrument shown by Fig. 2 may be constructe,gwithin a sheath 44 measuring approximately 2-1 /2 by about 4 millimetres. The lens system in such an instrument could have an objective lens 41 as large as about 2.2 mm.

Example Ill Fig. 3 compares the relative cross-sections of an instrument 60 constructed as shown in Fig. 1 and described in Example 1 with a series 61, 62, 63 and 64 of conventional instruments in current use. By way of comparison, the currently used instrument 61 (a Wolf operating arthroscope) contains a 2.5 mm objective lens 71, a 3 mm instrument channel 72 and a pair of irrigation channels 73 within a circular cylindrical sheath 74 packed with sufficient optic fibre 75 to provide adequate illumination. The sheath 74 is 6.5 mm in diameter. The thickness of the instrument of Example I is only slightly over half (about 54%) the diameter of the comparable Wolf instrument, and provides for better irrigation at the operative site.The cross-sectional area of the instrument of Example 1 is also significantly (more than 20%) smaller, thereby requiring a smaller puncture wound for insertion.

The other instruments 62, 63, 64 illustrated by Fig. 3 have diameters of 5, 2.5 and 2.2 millimetres, respectively, but include neither instrument nor irrigation channels. These instruments include only lenses and optical fibre lighting systems, and are useful for diagnostic applications only.

Figs. 4, 5 and 6 illustrate the placement of an arthroscope 60, constructed as taught by Example I, within a knee joint, shoulder joint and hip joint, respectively. The joints are shown in connection with a reference circle 80. Typical mature joints from the same male individual are illustrated compared to a reference circle with a radius of approximately 2-1 /2 centimetres. Of course, the joints of various individuals differ somewhat in size and configuration. Nevertheless, as may be seen from the drawings, a single arthroscope of standardized dimension can be used in all of the major joints of the majority of the human population.

Within tolerable limits, the sockets defined by the femur 81 and tibia 82 of the knee; the scapula 83 and humerus 84 of the shoulder; and the femur 85, ilium 86 and pubis 87 of the hip are generally similar in configuration in a given individual. Accordingly, relatively few arthroscopic instruments constructed in accordance with this invention are sufficient for a complete diagnostic and treatment service of these joints.

Although this disclosure has been directed specifically to arthroscopes and arthroscopy, with specific reference to certain illustrated embodiments, it is not intended to thereby limit the scope of the appended claims. It is within contemplation that the improvements disclosed and claimed herein may be adapted to endoscopes of various types. It is also contemplated that the teachings of this disclosure will lead directly to the development of practical instruments for the improved examination of smaller joints, such as those of the hands or feet. In such instruments, certain design changes, such as the desired radii of curvature for the arcuate side walls of the sheath, are expected. It is also within contemplation that the lens systems be adapted to provide a line of sight divergent from the central longitudinal axis of the sheath. An arthroscope in a sheath shaped as in Figs. 1 and 2, for example, may be provided with a lens system presenting a line of sight canted about 20 toward the concave surface.

The binocular version illustrated by Fig. 7 includes a pair of lens systems 91 and 92.

Claims (10)

1. An endoscope having structural elements including an optical system and a lighting system fixed within a rigid sheath, the cross-sectional configuration of the sheath, as viewed from its distal end, having major and minor axes intersecting at the geometric centre of said cross-section, and the dimension of the cross-section of the interior of the sheath along the said minor axis being just sufficient to accommodate the largest of said elements.

2. An endoscope as claimed in claim 1, wherein one of the opposing sides of the cross-section is concave and the other opposing side is convex.

3. An endoscope as claimed in claim 2, wherein the radius of curvature of each of said opposing sides is selected from between about 2 and about 3 centimetres.

4. An endoscope as claimed in any one of claims 1 to 3, wherein the opposing sides of the cross-section are approximately parallel each other.

5. An endoscope as claimed in any one of claims 1 to 4, wherein said lighting system includes optic fibres arranged within the interstitial spaces between elements contained within a sheath and the side walls of the sheath.

6. An endoscope as claimed in any one of claims 1 to 5, including a lens system element and an irrigation system element in sideby-side relationship along approximately the said major axis.

7. An endoscope as claimed in any one of claims 1 to 6, wherein the opposing sides of said cross-section which intersect said minor axis are each arcuate on a radius selected to approximately match the contours of adjacent bone surfaces comprising a joint.

8. An endoscope as claimed in any one of claims 1 to 7, wherein said sheath has a cross-sectional configuration, as viewed from its distal end, defined by a pair of approximately parallel longer sides and a pair of shorter sides.

9. An endoscope as claimed in any one of claims 1 to 8, including a pair of lens systems spaced along said major axis and approximately parallel the longitudinal axis of said sheath, and optic fibres packed in the interstices between the other said elements and the interior surface of said sheath.

10. An endoscope as claimed in any one of claims 1 to 9, wherein said sheath is rigid and has a cross-sectional configuration, as viewed from its distal end, shaped approximately as a parallelogram.