阅读说明：本技术 一种股骨大转子保护钢板 (Protective steel plate for greater trochanter of femur ) 是由 贾伟涛 姜达君 于 2020-12-28 设计创作，主要内容包括：本发明公开了一种股骨大转子保护钢板,包括：钢板本体,钢板本体呈板体结构；钢板本体的中部开设有一滑动孔,滑动孔呈圆角矩形设置,且滑动孔的长度方向沿钢板本体的长度方向设置；钢板本体开设有三钢缆孔组,三钢缆孔组分别开设于钢板本体的上部、钢板本体的中部和钢板本体的下部；每一钢缆孔组均包括两个钢缆孔,每一钢缆孔组的两钢缆孔内分别固定有一钢丝的两端,钢丝的中部围绕股骨远离钢板本体的一侧设置,钢板本体通过三钢丝绑紧于股骨的外侧。通过对本发明的应用,可以辅助修补股骨外侧壁,且为钢丝捆扎修复以及固定股骨提供安装位置；进一步促进了股骨的愈合,提高钢板本体的稳定性。(The invention discloses a femoral greater trochanter protection steel plate, which comprises: the steel plate body is of a plate body structure; the middle part of the steel plate body is provided with a sliding hole which is arranged in a round corner rectangle, and the length direction of the sliding hole is arranged along the length direction of the steel plate body; the steel plate body is provided with three steel cable hole groups which are respectively arranged at the upper part of the steel plate body, the middle part of the steel plate body and the lower part of the steel plate body; each steel cable punch combination all includes two steel cable holes, is fixed with the both ends of a steel wire in two steel cable holes of each steel cable punch combination respectively, and the middle part of steel wire sets up around one side that the steel sheet body was kept away from to the thighbone, and the steel sheet body ties up in the outside of thighbone through three steel wires. By applying the invention, the repair of the outer side wall of the femur can be assisted, and the installation position is provided for steel wire bundling repair and femur fixation; further promoting the healing of the thighbone and improving the stability of the steel plate body.)

1. A femoral greater trochanter protective steel plate, comprising:

the steel plate body is of a plate body structure and is approximately arranged in a rounded rectangle shape, the steel plate body is fixedly arranged on the outer side of the femur, and the length direction of the steel plate body is arranged along the vertical direction;

the middle part of the steel plate body is provided with a sliding hole which is arranged in a rounded rectangle, and the length direction of the sliding hole is arranged along the length direction of the steel plate body;

the steel plate body is provided with three steel cable hole groups which are respectively arranged at the upper part of the steel plate body, the middle part of the steel plate body and the lower part of the steel plate body;

wherein, each steel cable punch combination all includes two steel cable holes, each two of steel cable punch combination the steel cable hole all is in same level, each two of steel cable punch combination the steel cable hole set up respectively in the both sides of steel sheet body, each two of steel cable punch combination the steel cable is downthehole to be fixed with the both ends of a steel wire respectively, the middle part of steel wire centers on the thighbone is kept away from one side setting of steel sheet body, the steel sheet body passes through three the steel wire tighten in the outside of thighbone.

2. The femoral trochanter protective steel plate of claim 1, wherein the steel plate body is anatomically designed, the upper portion of the steel plate body is curved toward the femur relative to the middle portion of the steel plate body, and the steel plate body is disposed in close proximity to the outer surface of the femur.

3. The femoral trochanter protective steel plate of claim 1, wherein the sliding hole is operatively fitted with an intramedullary nail having one end inserted into the femur, and the width of the sliding hole is slightly larger than the diameter of the intramedullary nail.

4. The protective steel plate for femoral greater trochanter according to claim 1, wherein two first fixing holes are formed on one side of the steel plate body, one of the first fixing holes is disposed on the upper portion of the steel plate body, the other of the first fixing holes is disposed on the lower portion of the steel plate body, two second fixing holes are formed on the other side of the steel plate body, one of the second fixing holes is disposed on the upper portion of the steel plate body, the other of the second fixing holes is disposed on the lower portion of the steel plate body, a first screw is operatively disposed in each of the two first fixing holes and the two second fixing holes, and one end of each of the four first screws is inserted into the femoral bone.

5. The femoral greater trochanter protection steel plate as claimed in claim 4, wherein the upper portion of the steel plate body is further provided with a third fixing hole, a second screw is operatively installed in the third fixing hole, one end of the second screw is inserted into the femur, and one end of the second screw hole is obliquely and downwardly arranged.

6. The femoral greater trochanter protection steel plate according to claim 1, wherein the upper portion of the steel plate body is further provided with two anti-rotation nail holes, the two anti-rotation nail holes are respectively arranged on two sides of the steel plate body, the two anti-rotation nail holes are symmetrically arranged, at least one of the two anti-rotation nail holes is provided with a hollow nail, and one end of the hollow nail is inserted into the femoral bone.

7. The femoral greater trochanter protection steel plate as claimed in claim 1, wherein the two anti-rotation nail holes are both oval and the long axis of the two anti-rotation nail holes is both arranged along the length direction of the steel plate body.

8. The protective steel plate for femoral greater trochanter as claimed in claim 1, wherein the axis of each cable hole is inclined to the surface of the steel plate body on the side away from the femur.

9. The femoral greater trochanter protection steel plate of claim 1, wherein the thickness of the steel plate body is gradually reduced from bottom to top.

10. The femoral greater trochanter protective steel plate of claim 1, wherein one side of the steel plate body near the femur is provided with a plurality of grooves.

Technical Field

The invention relates to the technical field of medical instruments, in particular to a femoral greater trochanter protection steel plate.

Background

With the aging of the global population, the incidence rate of intertrochanteric fracture of femur is continuously increased, and the number of people in China is about 100 ten thousand times per year at present. Old patients mostly have various basic diseases, after fracture occurs, if the old patients lie in bed for a long time, the risk of complications such as lower limb venous thrombosis, pulmonary embolism, falling pneumonia, bedsore and the like can be obviously increased, and the fracture is also called as 'last fracture of life'. Therefore, the stronger internal fixation is selected to promote fracture healing, so that the patient can get out of bed for activity in the early days, and the method has important significance for reducing complications and mortality.

The involvement of the fracture between the trochanters of the femur to the type of the lateral wall accounts for 58.3%, which is a clinical and intractable problem, and no effective method is provided for solving the problem. Although the traditional intramedullary nail technology is the first choice for treatment, the fracture type with the fractured outer side wall cannot be effectively fixed by using the intramedullary nail, the failure rate is extremely high, the reduction, nail placement and other operations in the operation have great difficulty, and about 22 percent of patients need to carry out secondary repair operations. The lateral wall is usually anatomically referred to as the superior to the vastus lateralis, inferior to the lateral cortex in the lesser trochanter plane. The integrity of the lateral wall is of paramount importance for the stability of the internal fixation and the clinical prognosis. The repair outer side wall can support the proximal femoral head and neck bone block, and the head and neck bone block is allowed to slide outwards along the sliding shaft of the lag screw in a limited way, so that the bone blocks are in close contact; the rotation and the inversion of the femoral head and neck bone block and the inward shift of the femoral shaft can be resisted; meanwhile, the outer side action points of three-point stress of the broken nail head medullary nail can be provided, and the stability of internal fixation is improved. However, such fractures. Until now, no special internal fixing instrument is clinically used for repairing the outer side wall, and only steel plates used at other positions can be used instead.

Disclosure of Invention

In view of the above, in order to solve the above problems, an object of the present invention is to provide a femoral greater trochanter protection steel plate, comprising:

the steel plate body is of a plate body structure and is approximately arranged in a rounded rectangle shape, the steel plate body is fixedly arranged on the outer side of the femur, and the length direction of the steel plate body is arranged along the vertical direction;

the middle part of the steel plate body is provided with a sliding hole which is arranged in a rounded rectangle, and the length direction of the sliding hole is arranged along the long axis direction of the steel plate body;

the steel plate body is provided with three steel cable hole groups which are respectively arranged at the upper part of the steel plate body, the middle part of the steel plate body and the lower part of the steel plate body;

wherein, each steel cable punch combination all includes two steel cable holes, each two of steel cable punch combination the steel cable hole all is in same level, each two of steel cable punch combination the steel cable hole set up respectively in the both sides of steel sheet body, each two of steel cable punch combination the steel cable is downthehole to be fixed with the both ends of a steel wire respectively, the middle part of steel wire centers on the thighbone is kept away from one side setting of steel sheet body, the steel sheet body passes through three the steel wire tighten in the outside of thighbone.

In another preferred embodiment, the upper portion of the steel plate body is curved toward the femur relative to the middle portion of the steel plate body, and the steel plate body is disposed in close contact with the outer surface of the femur.

In another preferred embodiment, an intramedullary nail is operatively mounted in the sliding hole, one end of the intramedullary nail is inserted into the femur, and the width of the sliding hole is slightly larger than the diameter of the intramedullary nail.

In another preferred embodiment, two first fixing holes are formed in one side of the steel plate body, one of the first fixing holes is disposed on the upper portion of the steel plate body, the other of the first fixing holes is disposed on the lower portion of the steel plate body, two second fixing holes are formed in the other side of the steel plate body, one of the second fixing holes is disposed on the upper portion of the steel plate body, the other of the second fixing holes is disposed on the lower portion of the steel plate body, a first screw is operatively installed in each of the two first fixing holes and the two second fixing holes, and one end of each of the four first screws is inserted into the femur.

In another preferred embodiment, the upper portion of the steel plate body further defines a third fixing hole, a second screw is operatively installed in the third fixing hole, one end of the second screw is inserted into the femur, and one end of the second screw hole is disposed obliquely downward.

In another preferred embodiment, the upper portion of the steel plate body is further provided with two anti-rotation nail holes, the two anti-rotation nail holes are respectively arranged on two sides of the steel plate body, the two anti-rotation nail holes are symmetrically arranged, at least one of the two anti-rotation nail holes is internally provided with a hollow nail, and one end of the hollow nail is inserted into the femur.

In another preferred embodiment, the two anti-rotation nail holes are both in an oval shape, and the long axes of the two anti-rotation nail holes are both arranged along the length direction of the steel plate body.

In another preferred embodiment, the axis of each cable hole is inclined with respect to the surface of the steel plate body on the side away from the femur.

In another preferred embodiment, the thickness of the steel plate body is gradually reduced from bottom to top.

In another preferred embodiment, a plurality of grooves are formed on one side of the steel plate body close to the femur.

Due to the adoption of the technical scheme, compared with the prior art, the invention has the following positive effects: by applying the invention, the femoral outer side wall can be repaired in an auxiliary way, and an anchoring position is provided for steel wire bundling repair and fracture block fixation; further improve the stability of internal fixation, promoted the healing of thighbone, and adopted the limited contact design to reduce the contact between steel sheet body and the periosteum, guaranteed the blood supply.

Drawings

FIG. 1 is a first schematic view of a femoral greater trochanter protective steel plate of the present invention;

FIG. 2 is a second schematic view of a femoral greater trochanter protective steel plate of the present invention;

FIG. 3 is a schematic view of an elongated embodiment of a femoral greater trochanter protection steel plate of the present invention;

fig. 4 is a schematic view of the elongated installation of the femoral greater trochanter protection steel plate of the present invention.

In the drawings:

1. a steel plate body; 11. a slide hole; 12. a steel cable hole; 2. a steel wire; 3. intramedullary nail head intramedullary nail; 13. a first fixing hole; 14. a second fixing hole; 4. a first screw; 15. a third fixing hole; 5. a second screw; 16. anti-rotation nail holes; 6. hollow nails; 7. the femur; 8. a main intramedullary nail; 9. and (4) a groove.

Detailed Description

The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.

As shown in fig. 1 and 2, a femoral greater trochanter protection steel plate of a preferred embodiment is shown, which comprises: the steel plate comprises a steel plate body 1, wherein the steel plate body 1 is of a plate body structure, the steel plate body 1 is approximately arranged in a round corner rectangle shape, the steel plate body 1 is fixedly arranged on the outer side of a femur 7, and the long axis direction of the steel plate body 1 is arranged along the vertical direction; a sliding hole 11 is formed in the middle of the steel plate body 1, the sliding hole 11 is arranged in a rounded rectangle shape, and the length direction of the sliding hole 11 is arranged along the length direction of the steel plate body 1; the steel plate body 1 is provided with three steel cable holes 12, and the three steel cable holes 12 are respectively arranged at the upper part of the steel plate body 1, the middle part of the steel plate body 1 and the lower part of the steel plate body 1; wherein, each cable hole 12 group all includes two cable holes 12, two cable holes 12 of each cable hole 12 group all are in same level, two cable holes 12 of each cable hole 12 group set up respectively in the both sides of steel sheet body 1, be fixed with the both ends of a steel wire 2 respectively in two cable holes 12 of each cable hole 12 group, the middle part of steel wire 2 is around the one side setting that steel sheet body 1 was kept away from to thighbone 7, steel sheet body 1 ties up in the outside of thighbone 7 through three steel wires 2. Furthermore, two ends of each steel wire 2 are fixed in two steel cable holes 12 at the same horizontal height in a binding and knotting mode, each femoral greater trochanter protection steel plate is at least provided with three groups of the steel cable holes 12, each group of the steel cable holes 12 comprises two steel cable holes 12 at the same horizontal position, and the two steel cable holes 12 are arranged on the left side and the right side of the steel plate body 1 when the sight of medical staff is over against the steel plate body 1; specifically, each set of cable holes 12 is correspondingly installed with a steel wire 2, and each steel wire 2 is wound and fixed, so that the whole steel plate body 1 is fixed with the outer side of the femur 7 through the steel wire 2, the outer side of the femur 7 specifically refers to the side facing the protrusion of the greater trochanter of the femur 7, and provides an installation position for the intramedullary nail head intramedullary nail 3 through the sliding hole 11, and provides a proper driving angle and position for the intramedullary nail head intramedullary nail 3 through the sliding hole 11. Further, the width of the steel plate body 1 may be 22mm, the length thereof is 80mm, and the overall shape of the steel plate body 1 adopts the medical anatomical structure, so as to be closer to the surface of the femur 7, and reduce the protrusion of the metal object at the vastus lateralis. In another preferred embodiment, the opening axis of the cable hole 12 is inclined at 30 ° to the surface of the steel plate body 1, so that the cable can conveniently pass through, especially for comminuted fractures, the cable hole is beneficial to stabilizing fracture blocks through a steel wire 2 binding technology, the mechanical stability is improved, and more specifically, the upper, middle and lower three groups of cable holes 12 can respectively fix the greater trochanter, the lesser trochanter and the femoral shaft free bone blocks of the femur 7.

Further, as a preferred embodiment, the steel plate body 1 is designed in an anatomical manner, the upper portion of the steel plate body 1 is curved toward the femur 7 relative to the middle portion of the steel plate body 1, and the steel plate body 1 is disposed closely to the surface of the outer side of the femur 7. Further, the bending of the upper part of the steel plate body 1 is closely matched with the greater trochanter convex part of the upper end of the femur 7, and the edge design of low incisura is adopted at the upper end of the steel plate body 1, so that irritation of the steel plate body 1 to soft tissues of a patient is reduced.

Further, as a preferred embodiment, an intramedullary nail 3 is operatively mounted in the sliding hole 11, one end of the intramedullary nail 3 is inserted into the femur 7, and the width of the sliding hole 11 is slightly larger than the diameter of the intramedullary nail 3. Furthermore, the length direction of the sliding hole 11 is arranged along the length direction of the steel plate body 1, so that a larger insertion angle of the intramedullary nail head intramedullary nail 3 can be utilized, and the intramedullary nail head intramedullary nail 3 is matched with the sliding hole 11, so that the direction of the intramedullary nail head intramedullary nail 3 is not influenced according to the condition; preferably, an intramedullary nail head intramedullary nail 3 in a Gamma3 model intramedullary nail system is adopted, the diameter of which is 10.5mm, the length of the sliding hole 11 is 27mm, and the width of which is 27 mm; in actual operation, the intramedullary nail head intramedullary nail 3 is driven into a position which is lower than the center of the neck of the femur 7 at a proper angle, so that the intramedullary nail head intramedullary nail 3 can be suitable for the installation and fixation of the intramedullary nail head intramedullary nail of patients in various conditions; and the support is provided for the tail end of the intramedullary nail head intramedullary nail 3, the fixing strength of the intramedullary nail head intramedullary nail 3 is enhanced, the intramedullary nail stress is reduced, and the important intramedullary nail head intramedullary nail 3 is prevented from being broken.

Further, as an embodiment of a preferred embodiment, two first fixing holes 13 are opened on one side of the steel plate body 1, wherein one first fixing hole 13 is disposed on the upper portion of the steel plate body 1, another first fixing hole 13 is disposed on the lower portion of the steel plate body 1, two second fixing holes 14 are opened on the other side of the steel plate body 1, one second fixing hole 14 is disposed on the upper portion of the steel plate body 1, another second fixing hole 14 is disposed on the lower portion of the steel plate body 1, a first screw 4 is operatively installed in each of the two first fixing holes 13 and the two second fixing holes 14, and one end of each of the four first screws 4 is inserted into the femur 7.

Further, as a preferred embodiment, the upper portion of the steel plate body 1 is further provided with a third fixing hole 15, a second screw 5 is operatively installed in the third fixing hole 15, one end of the second screw 5 is inserted into the femur 7, and one end of the hole of the second screw 5 is disposed obliquely downward. Further, the first screw 4 or the second screw 5 with the diameter of 3.5mm is installed through five fixing hole positions of the two first fixing holes 13, the two second fixing holes 14 and the third fixing hole 15, and the first screw 4 and the second screw 5 are preferably cortical screws, meanwhile, the two first fixing holes 13, the two second fixing holes 14 and the third fixing hole 15 are all arranged by universal holes, specifically, the universal holes are designed to be hole positions with the diameter close to one end of the femur 7 larger than that far from one end of the femur 7, so that the first screw 4 or the second screw 5 is provided with an inclination range capable of being shifted by 15 degrees relative to the central axis of the hole positions. Meanwhile, the first fixing hole 13, the second fixing hole 14 and the third fixing hole 15 are arranged in a staggered mode, so that the stress on the steel plate body 1 is prevented from being concentrated too much; the steel plate body 1 is fixed on the femur 7 through the first screw 4 and the second screw 5, so that the stabilizing effect of the surface of the steel plate body 1 close to the femur 7 on the outer side wall of the femur 7 is exerted; meanwhile, the cortical bone screw can be used for better fixing the crushed bone blocks, and the stability of the whole structure is improved in the first step.

Further, as a preferred embodiment, the upper portion of the steel plate body 1 is further provided with two anti-rotation nail holes 16, the two anti-rotation nail holes 16 are respectively disposed at two sides of the steel plate body 1, the two anti-rotation nail holes 16 are symmetrically disposed, at least one of the two anti-rotation nail holes 16 is provided with a 6.5mm hollow nail 6, and one end of the hollow nail 6 is inserted into the femur 7. Further, through the design of the anti-rotation nail hole 16, the hollow nail 6 (the proximal compression screw of the intramedullary nail) is prevented from effectively resisting rotation, so that the anti-rotation stability of the intramedullary nail at the position separated from the proximal end is improved; in order to allow an operator to select different holes to drive the hollow nail 6 according to the head intramedullary nail position and the femur neck anatomical structure, the two anti-rotation nail holes can be selected to be a hollow point 6 to be arranged in an anti-rotation nail hole 16 with a proper position according to actual requirements; specifically, the hollow nail 6 can be correspondingly adjusted in angle according to the anteversion angle of the femoral neck, and is thickly penetrated through the fracture line from the front to the back.

Further, as a preferred embodiment, the two anti-rotation nail holes 16 are both disposed in an elliptical shape, and the long axes of the two anti-rotation nail holes 16 are both disposed along the length direction of the steel plate body 1. Furthermore, the elliptical hole is convenient for the angle adjustment of the hollow nail 6 in the operation, so that the hollow nail can be placed in the best fixing position; the minor axis length of each anti-spin nail hole 16 is 6.8 mm. The long axis length is 8.8mm, the short axis of the anti-rotation nail hole 16 is larger than the diameter of the screw rod, and the inclined pose adjustment of the hollow nail 6 at the inner side within the range of deviating from the central axis of the anti-rotation nail hole 16 by 15 degrees can be allowed, wherein the diameter specification of the hollow nail 6 is 6.5mm, the integral interlocking fixation is realized, and the better rotation stability is provided for the whole femur 7; in the actual operation process, the intramedullary nail head intramedullary nail 3 may be placed in a forward or backward direction, so the anti-rotation nail holes 16 are designed in a symmetrical mode that every two anti-rotation nail holes 16 are distributed on the left side and the right side of the steel plate body 1.

Further, as a preferred embodiment, the axis of each cable hole 12 is inclined to the surface of the steel plate body 1 on the side away from the femur 7. Further, the steel wire 2 in the steel cable hole 12 is conveniently placed in, and the whole femoral greater trochanter is effectively pressurized, so that local clamping and pressing are avoided.

Further, as a preferred embodiment, the thickness of the steel plate body 1 is gradually reduced from bottom to top. Further, the thickness of the upper end (i.e. the end close to the large rotor) of the steel plate is 1mm, and gradually thickens to 1.2mm from the position 1/3 length away from the upper end of the steel plate, and continuously gradually thickens to 3.5mm towards the lower end of the steel plate body 1; and the steel plate body 1 adopts a low-notch design.

Further, as a preferred embodiment, a plurality of grooves 9 are formed on one side of the steel plate body 1 close to the femur 7. Further, each groove 9 is a cylindrical groove which is opened on one side of the steel plate body 1 close to the femur 7 along the horizontal direction, so that the contact area between the steel plate body and the periosteum of the femur 7 is reduced as much as possible, and the blood supply is protected.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope and the implementation manner of the present invention.

The present invention also has the following embodiments in addition to the above:

in a further embodiment of the present invention, as shown in fig. 3, the steel plate main body extension embodiment of the present invention is characterized in that, compared with the above-mentioned steel plate main body with standard specification, the length is extended downward to 10mm, so that the sliding hole 11 is located at the central part of the whole extension type steel plate main body 1, and six cable holes 12 and seven fixing holes are provided.

In a further embodiment of the present invention, as shown in fig. 4, the present invention is specifically mounted and fixed to the femur 7 in the actual use process, and is characterized in that the present invention further comprises a main nail 8 of the intramedullary nail for cooperating with the integral fixation, and the main body of the intramedullary nail penetrates through the greater trochanter and the diaphysis of the femur 7 from top to bottom in the actual use process.

Furthermore, in the actual process of performing the operation on the patient, the patient adopts general anesthesia and takes the supine position; selecting a Watson-Jones approach to expose the outer side wall of the proximal end of the femur 7, axially drawing, abducting and internal rotating, adducting the lower limb of the affected side for resetting, simultaneously resetting the fractured outer side wall bone block through an auxiliary tool under direct vision, and temporarily placing a Kirschner wire for fixing; c-arm machine perspective confirms that the fracture force line meets the standard; placing the steel plate body 1 at a corresponding anatomical position outside the femur 7, respectively placing the two cortical screws through the far-end fixing hole and the near-end fixing hole of the steel plate body 1 to fix the steel plate body 1 on the outer side wall, and confirming that the sliding hole 11 is projected in the contour line of the femoral neck through the front side perspective of the C-arm machine and is consistent with the axial direction of the sliding hole; making a 5cm incision along the vertex of the greater trochanter towards the proximal end, cutting the aponeurosis of gluteus maximus, exposing the inner side edge of the vertex of the greater trochanter, and placing a guide pin; after the C-arm machine confirms that the position of the guide pin is ideal, the marrow is expanded to a femoral medullary cavity, the long guide pin is replaced to the far end of the femur, and an intramedullary nail main nail 8 with a proper length is selected through the depth measurement of the guide pin; selecting medullary cavities with different sizes in sequence to expand the medullary to an ideal size, inserting the intramedullary nail main nail 8 by a guider, removing the guide pin, and confirming the position of the intramedullary nail main nail 8 to be correct by a C-arm machine; the intramedullary nail head intramedullary nail 3 is placed along the femoral neck axis through the sliding hole 11 until the femoral head cartilage is 5mm below; a first screw 4 and a second screw 5 which are placed in a far-end interlocking way under perspective; implanting a hollow nail 6 to the femoral head direction through a nail rotating prevention hole 16 at the near end of the steel plate body 1; the other screws are sequentially arranged, and whether the steel wire 2 is used for binding the bone block through the steel cable hole 12 is determined according to the fracture crushing condition in the operation; c-arm machine perspective confirms that the fracture force line is satisfactory, the intramedullary nail head intramedullary nail 3 and the steel plate body 1 are satisfactory in position, the wound is washed, and the suture is performed layer by layer.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.