CN108524062B

CN108524062B - Femoral stem

Info

Publication number: CN108524062B
Application number: CN201810156443.8A
Authority: CN
Inventors: 吴承锦
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-02-24
Filing date: 2018-02-24
Publication date: 2020-09-04
Anticipated expiration: 2038-02-24
Also published as: CN108524062A

Abstract

A femoral stem, comprising: the handle body is internally provided with a channel, the femoral neck extends downwards to form a transmission rod which reciprocates in the channel, and a first spring is arranged between the outer circumference of the transmission rod and the channel. A second spring is arranged between the position, close to the inner side, of the upper third of the transmission rod and the channel, and the compression stroke of the second spring is shorter than that of the first spring. A gear and rack meshing section is arranged between the outer side wall of the transmission rod and the side wall of the channel, a pull wire is wound on a winding drum coaxial with the gear, and the other end of the pull wire is fixed at the upper one third position of the transmission rod. In the process of downward movement of the transmission rod, the second spring is compressed to the limit position earlier than the first spring, partial pressure stress applied to the inner side is transmitted to the proximal end of the femur, the rack driving gear rotates, the pull wire pulls the upper third of the transmission rod downwards, and the upward tensile stress borne by the transmission rod is relieved. The invention is more consistent with the way of bearing and conducting stress of the femur in physiological state.

Description

Femoral stem

Technical Field

The invention relates to the field of medical instruments, in particular to a femoral stem.

Background

The femoral stem prosthesis is a surgical implant used to replace the femoral part of the human hip joint. The femoral stem includes a generally cylindrical femoral neck and a generally rod-shaped stem body. The handle body extends from the femoral neck and is inserted into the femoral medullary cavity, the femoral neck is connected with the femoral head, and the femoral head is embedded in the acetabulum prosthesis. The femoral head may rotate within the acetabular prosthesis. After the handle body is inserted into the femoral cavity, the handle body and the inner wall of the proximal femur end can be connected and fixed in various forms, such as bone cement and press fit biological fixation, so that the femoral handle can conduct the borne action stress to the bone of the proximal femur end, and the purpose of conducting stress when a person walks is achieved.

When the human body stands on one foot, the femoral stem is pressed by 3 times of the body weight. In the prior art, the maximum strength of the force which can be borne by the joint of the lateral surface of the femoral stem and the marrow cavity is about 4 to 5 times of the body weight of a human body.

The existing femoral stem prosthesis, whether in an integrated structure or an assembled structure, can only be suitable for walking but not jumping and running, because when a person jumps and runs, the hip joint bears larger stress which exceeds the strength of the combination of the femoral stem and the femoral medullary cavity in the prior art, the prosthesis is loosened.

Disclosure of Invention

To solve the above problems, the present invention provides a femoral stem comprising: a handle body (2), wherein a channel (21) is arranged in the handle body (2); a femoral neck (1), the femoral neck (1) having a downwardly extending drive rod (11), the drive rod (11) being inserted in the channel (21) so as to be capable of reciprocating in the channel (21); a first spring, wherein a first annular groove (111) is arranged on the outer wall of the transmission rod (11), a first annular flange (211) is arranged in the channel (21), the first annular flange is embedded in the first annular groove, and the first spring is arranged in the first annular groove; the second spring is provided with a second groove (141) at the position, close to the inner side, of the upper one third of the transmission rod, the channel (21) extends into the second groove (141) to form a second boss (241), an installation column (142) penetrating through the second boss along the axial direction of the channel (21) is arranged in the second groove (141), the installation column (142) extends from the upper end face of the second groove (141) to the lower end face of the second groove, the second spring (143) is sleeved on the installation column (142) between the upper end face of the second boss and the upper end face of the second groove, and the compression stroke of the second spring (143) is shorter than that of the first spring (112); a gear rack meshing section, a gear rack meshing section is arranged between the outer side wall of the transmission rod and the side wall of the channel, a winding drum (215) is coaxially arranged with the gear, a pull wire (153) is wound on the winding drum (215), a pull wire channel (152) for the pull wire to penetrate and extend to the upper third of the transmission rod is arranged on the transmission rod (11), the other end of the pull wire (153) is embedded and fixed at the upper third of the transmission rod, wherein, after the handle body (2) is inserted into the femoral medullary cavity, the channel (21) is communicated with the femoral medullary cavity (100), and in the process of downward movement of the transmission rod (11), the second spring (143) is compressed to the limit position earlier than the first spring (112), so that the transmission rod (11) transmits partial pressure stress applied to the inner side to the proximal end of the femur through the second spring (143) to reduce the pressure stress born by the transmission rod (11) in advance, meanwhile, the rack (151) drives the gear (214) to rotate anticlockwise, the pull wire (153) wound on the winding drum (215) pulls the upper third of the transmission rod (11) downwards, upward tensile stress borne by the transmission rod (11) is relieved, the first spring (112) is compressed to the limit position along with the continuous downward movement of the transmission rod (11), the transmission rod (11) transmits the stressed compressive stress and tensile stress to the proximal femur end 200 and the distal femur end through the first spring (112) and the second spring (143), so that the whole femur bears pressure, when the transmission rod (11) moves upwards, and after the first spring (112) is completely extended, the second spring (143) can still transmit the stressed compressive stress borne by the transmission rod (11) to the proximal femur.

Preferably, one or more sliding grooves (118) are formed in the transmission rod (11) in the length direction of the transmission rod, corresponding to each sliding groove (118), a sliding piece (216) extends out of the channel (21) towards the inside of the sliding groove, two side faces of the sliding piece (216) are attached to two inner side faces of the sliding groove (118), and the length of the sliding groove (118) is longer than that of the sliding piece (216), so that the transmission rod can slide up and down and can transmit torque to the proximal end of the femur.

Preferably, high-wear-resistant rubber is arranged on two side faces of the sliding chute (118) which are in contact with the sliding sheet.

Preferably, a third annular groove (120) is arranged in the channel (21), an annular sliding sleeve (220) is arranged in the third annular groove, a sliding rail (221) along the length direction of the channel (21) is further arranged in the third annular groove (120), the annular sliding sleeve (220) is slidably mounted on the sliding rail (221), the annular sliding sleeve (220) extends out of the first annular flange (211) towards the radial inner side of the transmission rod, and a third spring (119) is further arranged between the lower end face of the annular sliding sleeve (220) and the lower end face of the third annular groove (120), so that the first spring (112) and the third spring (119) are sequentially compressed to bear pressure load.

Preferably, a fourth groove (132) is further provided at the lower end of the driving rod (11), a pressure regulating rod (130) is provided in the fourth groove (132), a fourth boss (133) is provided at the upper end of the pressure regulating rod (130), a fifth boss (134) blocking the fourth boss (133) is provided at the lower end of the fourth groove (132), and a fourth spring (131) is provided between the upper end surface of the pressure regulating rod (130) and the upper end surface of the fourth groove (132).

Preferably, one or more sealing rings or piston rings are also provided on the outer wall of the drive rod to seal the channel.

Preferably, the transmission rod is conical with a diameter decreasing from top to bottom, and correspondingly, the passage of the shank is also conical with a diameter decreasing from top to bottom.

Preferably, the taper of the drive link is between 1 ° and 3 °.

Preferably, a plurality of cutting grooves (231) vertically extending to the lower end surface of the handle body are arranged at the lower part of the handle body so as to enhance the elastic deformability of the lower part of the handle body.

Preferably, the lower end of the transmission rod is further provided with a detection unit for detecting the extension amount of the transmission rod exceeding the lower end of the handle body and the pressure in the femoral cavity, and the detection unit is provided with a Bluetooth module which is matched with external Bluetooth equipment and used for transmitting detected data.

The invention drives the transmission rod to reciprocate through the first spring, thereby respectively transmitting the larger stress on the femoral neck to the bone at the proximal end and the distal end of the femur, and enlarging the stress area of the femoral stem prosthesis during stress transmission. Through gleitbretter and spout, can guarantee that the transfer line reciprocates, can transmit the moment of torsion that the transfer line received again to thighbone near-end. And before the first spring is not compressed to the limit position, the second spring arranged at one third of the upper part of the transmission rod is compressed in advance, so that the compressive stress on the inner side of the femur is transmitted to the proximal end of the femur in advance, and the compressive stress generated on the inner side of the transmission rod by quick impact force such as running jump can be relieved. Before the first spring is not compressed to the limit position, the pull wire arranged at the upper third position of the transmission rod is pulled downwards through the matching of the rack arranged at the outer side of the transmission rod and the gear arranged on the side wall of the channel, and the tension borne by the upper third position can be relieved. And, the pressure regulating pole through the fourth spring setting in the transfer line bottom can be according to the intracavitary pressure automatic adjustment femoral of thighbone, makes the intracavitary pressure of thighbone keep in reasonable within range. And moreover, the change of the body weight of the human body can be adapted by arranging a multi-stage compression spring. The way of bearing and conducting the stress of the femur in the physiological state is more consistent. Can meet the requirements of the personnel after hip replacement on violent activities such as jumping, running and the like.

Drawings

The above features and technical advantages of the present invention will become more apparent and readily appreciated from the following description of the embodiments thereof taken in conjunction with the accompanying drawings.

FIG. 1 is a first cross-sectional view of a femoral stem illustrating an embodiment of the present invention;

FIG. 2 is a partially enlarged view of the upper third of a femoral stem illustrating an embodiment of the present invention;

FIG. 3 is a sectional view taken along line A-A of FIG. 1;

FIG. 4 is a sectional view taken along line B-B of FIG. 1;

FIG. 5 is a second cross-sectional view of a femoral stem illustrating an embodiment of the present invention;

fig. 6 is a third sectional view showing a femoral stem according to an embodiment of the present invention;

fig. 7 is a bottom view showing a femoral stem according to an embodiment of the present invention.

Detailed Description

Embodiments of the femoral stem according to the present invention will be described below with reference to the accompanying drawings. Those of ordinary skill in the art will recognize that the described embodiments can be modified in various different ways, or combinations thereof, without departing from the spirit and scope of the present invention. Accordingly, the drawings and description are illustrative in nature and not intended to limit the scope of the claims. Furthermore, in the present description, the drawings are not to scale and like reference numerals refer to like parts.

As shown in fig. 1, the femoral stem of the present invention includes a femoral neck 1 and a stem body 2. The upper end of the femoral neck 1 is generally oval in shape, the upper end of the femoral neck 1 is connected to the femoral head 5 and is coupled to the acetabular cup (not shown) via the femoral head 5, and the stem 2 is adapted for insertion into the intramedullary canal 100 of the femur 6. The stem 2 is proximal to the bone in-growth portion of the femur 6 and distal to the bone in-growth portion of the medullary cavity 100. A channel 21 is provided in the stem body 2, the channel 21 being a through hole opened at the upper and lower ends thereof, the channel 21 communicating with the marrow cavity 100 through the opened lower end thereof.

And the femoral neck 1 has a transmission rod 11 extending downwardly from the upper end, the transmission rod 11 being inserted into the passage 21 of the stem body 2, and the transmission rod 11 being reciprocable in the passage 21 along the length of the passage 21.

A first annular flange 211 is provided in the channel 21, and a first annular groove 111 is provided on the outer wall of the transmission rod 11 corresponding to the first annular flange 211, and the first annular flange 211 is fitted into the first annular groove 111. Furthermore, a first spring 112 is disposed between an upper end surface of the first annular groove 111 and an upper end surface of the first annular flange 211, and the first spring 112 is sleeved on an outer wall of the first annular groove 111. When the femoral neck 1 is not under pressure, the lower end surface of the first annular groove 111 and the lower end surface of the first annular flange 211 substantially abut against each other under the action of the spring force, and the lower surface 12 of the femoral neck 1 and the upper surface 23 of the stem body have a predetermined distance therebetween, which is substantially equal to the limit compression distance of the first spring 112. And the transmission rod 11 is flush with the bottom surface of the handle body 2.

The compressive stress experienced by a conventional femoral stem is experienced by the proximal end of the femur, which is in contact with the femur 6, and is subjected to a large impact when subjected to a strong impact, such as running, jumping, etc. In the embodiment, when the femoral neck 1 is under compressive stress, the spring 112 transmits the pressure to the contact interface 400 between the handle 2 and the proximal femur end 200, and the distal end of the transmission rod 11 extends out of the lower end of the handle 2 and enters the medullary cavity 100, the medullary cavity 100 is filled with medullary fluid, the volume of the medullary cavity 100 is fixed, and the distal end of the transmission rod 11 enters the medullary cavity 100 to press the medullary fluid, so that the pressure of the fluid in the medullary cavity 100 is increased. The pressure of the fluid in the marrow cavity 100 acts on the bottom surface of the transmission rod 11, creating an upward force. It can be seen that, through the transmission rod 11, the stress area is enlarged, and under the condition of keeping the stress of the joint part of the femoral stem 2 and the proximal femur 200, the stress which can not be borne by the femoral stem 2 and the proximal femur 200 is transmitted to the femoral bone at the distal end of the femoral stem 2.

After the femoral stem is installed in the bone cavity 6, the femoral head 5 is located on the inner side of the thigh, the side of the femoral stem facing the inner side of the thigh is hereinafter referred to as the inner side, and the opposite side is referred to as the outer side. The femoral head stress is the pressure which passes through the center of the femoral head 5 and forms a certain angle with the femoral stem, as shown in fig. 1, when the femoral head 5 is under the action of compressive stress F, the femoral neck 1 generates bending moment, the inner side of the transmission rod 11 bears the compressive stress, and the outer side bears the tensile stress. Also, the maximum stress of the femoral stem is typically located in the upper third of the length of the femoral stem. The external dimension of the femoral stem is originally small, and the transmission rod 11 is processed on the femoral stem which is originally integrated, so that the transmission rod 11 is likely to be broken due to large stress generated by rapid movement such as running and jumping. Therefore, the present embodiment provides a force reducing mechanism on both the inner side and the outer side, a second groove 141 is provided on the upper third of the transmission rod 11 toward the inner side, and the channel 21 extends out of the second groove 141 by a second boss 241. Further, a mounting post 142 penetrating the second boss 241 in the axial direction of the passage 21 is provided in the second groove 141, and the mounting post 142 extends from the upper end surface of the second groove 141 up to the lower end surface thereof. The second spring 143 is fitted over the mounting post 142. Specifically, the mounting post 142 is sleeved between the upper end surface of the second boss 241 and the upper end surface of the second groove 141. Therefore, the second spring 143 can be compressed or extended as the driving lever 11 moves up and down. Also, the second spring 143 has a shorter compression stroke than the first spring 112.

During the downward movement of the transmission rod 11, the first spring 112 is still in a state of being compressed downward, and before being uncompressed to the limit, the transmission rod 11 has a limited pressure transmitted to the handle body 2 through the first spring 112. And the second spring 143 has been compressed to an extreme position. That is, the transmission rod 11 transmits a part of the compressive stress to the handle 2 and further to the proximal femur 200 through the second spring 143, so as to reduce the compressive stress applied to the transmission rod 11 inside. Particularly, in a rapid motion such as jumping, a large impact force is instantaneously generated due to a relatively rapid generation of the compressive stress, and a part of the compressive stress is transmitted to the proximal end of the femur by the second spring 143 before the first spring 112 is compressed to the limit position, so that the compressive stress received by the inner side of the transmission lever 11 can be appropriately reduced.

As shown in fig. 2, a rack-and-pinion engagement section is further provided on the transmission lever 11 at a position toward the outside. Specifically, a rack 151 extending along the length of the transmission rod 11 is correspondingly provided with a gear 214 engaged with the rack 151 on the side wall of the passage 21 of the handle body 2. A winding drum 215 is coaxially arranged with the gear 214, a wire 153 is wound on the winding drum 215, a wire passage 152 through which the wire passes and extends to the upper third of the transmission rod 11 is arranged on the transmission rod 11, and the other end of the wire 153 is buried and fixed at the upper third of the transmission rod 11. When the transmission rod 11 moves due to downward impact of running and jumping, the transmission rod moves down rapidly, so that the rack 151 drives the gear 214 to rotate anticlockwise rapidly, the pull wire 153 wound on the winding drum 215 pulls the upper third part of the transmission rod 11 downwards, certain downward tensile stress is provided, certain offset effect is provided with the upward tensile stress applied to the transmission rod 11, and the tensile stress applied to the transmission rod 11 can be reduced. Of course, a plurality of pull wires may be provided and distributed in the upper third of the transmission rod 11 to make the pulling force of the pull wires 153 to the upper third of the transmission rod 11 uniform. As the rack 151 moves down, the wire 153 is gradually wound onto the drum 215.

As the transmission rod 11 moves downward, the first spring 112 is compressed to the limit position, and the transmission rod 11 transmits the compressive stress and the tensile stress applied thereto to the handle body 2 and further to the proximal femur 200 and the distal femur through the first spring 112. At this point, drive rod 11 still transmits a portion of the compressive stress to the proximal femur through second spring 143.

When the transmission rod moves upwards, after the first spring 112 is fully extended, the second spring 143 still has a certain amount of compression, and still transmits the compressive stress applied to the transmission rod 11 to the proximal femur 200. And the gear 214 rotates clockwise with the upward movement of the rack 151, and the pull wire 153 is gradually loosened until the transmission rod 11 is no longer stressed.

In the embodiment, the stress borne by the transmission rod is transmitted to the far end of the femur by the first spring, so that the stress borne by the near end of the femur can be relieved. And before the first spring is not compressed to the limit position, the second spring arranged at one third of the upper part of the transmission rod is compressed in advance, so that the compressive stress on the inner side of the femur is transmitted to the proximal end of the femur in advance, and the huge compressive stress generated on the inner side of the transmission rod by the quick impact force such as running jump can be relieved. Before the first spring is not compressed to the limit position, the pull wire arranged at the upper third position of the transmission rod is pulled downwards through the matching of the rack arranged at the outer side of the transmission rod and the gear arranged on the side wall of the channel, and the huge tension borne by the upper third position can be relieved.

In an alternative embodiment, the transmission rod 11 is subjected to torque while being subjected to pressure, a conventional femoral stem without a transmission rod is directly connected with the proximal end of the femur through bone ingrowth, and the torque applied to the femoral neck 1 is directly transmitted to the proximal end 200 of the femur. The femoral stem, which is pressed by the transmission rod 11, cannot transmit torque to the proximal femur 200 well because the transmission rod and the channel are connected in a sliding manner. Thus, as shown in fig. 3 and 4, one or more sliding grooves 118 are provided on the transmission rod 11 along the length of the transmission rod 11, and for each sliding groove 118, the channel 21 extends a sliding piece 216 into the transmission rod 11. The length of the slide slot 118 is longer than the length of the slide 216, such that the slide 216 can slide within the slide slot 118 along the length of the drive rod 11. Two side surfaces of the sliding piece 216 are attached to two inner side surfaces of the sliding groove 118. Through the sliding piece 216 and the sliding groove 118, the transmission rod 11 can be ensured to move up and down, and the torque applied to the transmission rod 11 can be transmitted to the proximal end of the femur.

Preferably, as shown in fig. 4, highly wear-resistant rubber 217 is provided on both side surfaces of the slide groove 118 contacting the slide pieces, so that the slide groove 118 can have an impact-damping effect and transmit torque to the handle body 2 when the slide pieces 216 press the side surfaces of the slide groove 118.

In an alternative embodiment, as shown in fig. 5, it is also possible to adapt to the body weight of the human body in different periods by providing a plurality of springs, and the following description will take two springs as an example. A third annular groove 120 is arranged in the channel 21, an annular sliding sleeve 220 is arranged in the third annular groove, a sliding rail 221 along the length direction of the channel 21 is further arranged in the third annular groove 120, and the annular sliding sleeve 220 is mounted on the sliding rail 221 and can move along the sliding rail 221 along the length direction of the transmission rod 11. The annular sliding sleeve 220 extends the above-mentioned first annular flange 211 towards the radial inner side of the transmission rod, and the first spring 112 is installed on the transmission rod between the upper end face of the first annular flange 211 and the upper end face of the first annular groove 111. And, a third spring 119 is further disposed below the annular sliding sleeve 220, specifically, the third spring 119 is disposed between a lower end surface of the annular sliding sleeve 220 and a lower end surface of the third annular groove 120. Wherein the first spring 112 and the third spring 113 are sequentially compressed to receive the pressure load. First, the first spring 112 is compressed, and as the first spring 112 is compressed, when the pressure reaches the minimum working load of the third spring, the annular sliding sleeve 220 presses the third spring 119 downwards, and the transmission rod 11 can move further downwards. By providing a spring with two stages of compression, it is possible to adapt to changes in the body weight of the person, which here also includes temporarily increasing the weight on the body in the form of a load. For example, the human body has only 90 jin of weight when the femoral stem is installed, and after a period of time when the femoral stem is installed, the body weight increases to 200 jin, and obviously, the body weight increases greatly. If there is only one level of spring in the femoral stem, i.e., first spring 112, then there is a significant weight gain, which causes both the proximal and distal femur to bear a significant amount of pressure, which is detrimental to femoral stem stabilization. Through setting up third spring 113, after weight gain is great, then third spring 113 can further cushion the load that the transfer line 11 received, is favorable to the long-term use of femoral stem.

In an alternative embodiment, as shown in fig. 6, a fourth groove 132 is further provided at the lower portion of the driving rod 11, a pressure regulating rod 130 is provided in the fourth groove, the upper end of the pressure regulating rod 130 has a fourth boss 133, and the lower end of the fourth groove 132 is provided with a fifth boss 134 blocking the fourth boss 133. A fourth spring 131 is provided between the upper end surface of the pressure regulating rod 130 and the upper end surface of the fourth groove 132. Although the above form of the drive rod extending into the medullary cavity helps the femoral stem to bear the load, increased pressure in the femoral hip cavity can present other potential problems. For example, excessive pressure may prevent venous reflux from causing femoral head necrosis. Therefore, to prevent excessive pressure in the medullary cavity, the pressure adjustment rod 130 is provided. When the pressure in the marrow cavity rises to a set pressure value and exceeds the minimum working load of the fourth spring 131 as the transmission rod 11 extends into the marrow cavity, the pressure regulating rod 130 is pressed upwards by the pressure in the marrow cavity to compress the fourth spring 131, and the retraction part of the transmission rod 11 can slightly reduce the pressure in the marrow cavity and reduce the safety risk. In addition, the femoral cavities of different human bodies have different pressure bearing capacities, and the pressure regulating rod 130 can enable the femoral stem to be generally suitable for the femoral cavities of most human bodies.

In an alternative embodiment, one or more sealing rings or piston rings 135, see fig. 2, are also provided on the outer wall of the transmission rod 11 for sealing the passage.

In an alternative embodiment, the transmission rod 11 is conical with a decreasing diameter from top to bottom, and correspondingly the channel 21 of the stem 2 is conical with a decreasing diameter from top to bottom, so that when the transmission rod 11 is moved downwards, it exerts a lateral compression force on the stem 2, which facilitates a tight fit with the proximal end of the femur during the early stages of femoral stem installation. And, preferably, the taper is between 1 ° and 3 °.

Further, as shown in fig. 7, at least 3 cutting grooves 231 extending vertically to the lower end surface of the shank 2 are provided in the lower portion of the shank 2, so that the lower portion of the shank 2 has a certain elastic deformability. When the transmission rod 11 with the taper moves downwards, the transverse extrusion force on the handle body 2 causes the handle body 2 to generate transverse elastic deformation, and further absorbs part of the impact force applied on the transmission rod 11. Theoretically, the closer the lower part of the femoral stem is in contact with the medullary cavity, the more obvious the proximal femur stress shielding phenomenon is. While the absence of contact between the lower femoral stem portion and cortical bone (i.e., cortical bone distributed over the peripheral surface of the bone) may reduce stress shielding, bone resorption, and thigh pain. Thus, reducing contact of the lower portion of the femoral stem with cortical bone helps to reduce proximal femoral stress shielding, but at the expense of reduced contact area for fixation and stress transmission. Therefore, usually the outer side of the lower part of the handle body 2 is not in close contact with cortical bone, and can be provided with a certain gap, and the lower part of the handle body 2 is provided with a plurality of cutting grooves, so that the handle body runs and jumps and the like under the action of the downward pressure of the transmission rod 11 to be in close contact with cortical bone, thereby not only effectively reducing the proximal femur stress shielding, but also not influencing the initial stability of prosthesis fixation.

In an alternative embodiment, a detection unit is also provided at the lower end of the transmission rod 11, which is able to detect the extension of the transmission rod 11 beyond the lower end of the handle 2 and the real-time pressure in the femoral cavity, and which has a bluetooth module that can be adapted to an extracorporeal bluetooth device, such as a computer, a mobile phone, etc., for transmittingAnd (4) data. By collecting and collating this data, the relationship between the amount of extension of the drive rod 11 and the pressure in the femoral cavity can be established. The weight range of the user can be calculated by combining the parameters of the spring, the data can be used for designing femoral stem prostheses in the future, the pressure in a femoral cavity of the user can be warned, femoral head necrosis caused by overhigh pressure in the femoral cavity can be prevented, and the user is advised to keep the weight in a certain range. For example, the elastic coefficient of the first spring used is 1.5X 10⁶N/m, the protrusion is between 2mm and 5mm, and in the case of a single leg bearing 4 times of body weight, the body weight range should be in the range of 75-187.5 KG.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A femoral stem, comprising:

a handle body (2), wherein a channel (21) is arranged in the handle body (2);

a femoral neck (1), said femoral neck (1) having a downwardly extending drive rod (11), said drive rod (11) being inserted in said channel (21) so as to reciprocate in the channel (21);

a first spring, wherein a first annular groove (111) is arranged on the outer wall of the transmission rod (11), a first annular flange (211) is arranged in the channel (21), the first annular flange is embedded in the first annular groove, and the first spring is arranged in the first annular groove;

the second spring is provided with a second groove (141) at the position, close to the inner side, of the upper one third of the transmission rod, the channel (21) extends into the second groove (141) to form a second boss (241), an installation column (142) penetrating through the second boss along the axial direction of the channel (21) is arranged in the second groove (141), the installation column (142) extends from the upper end face of the second groove (141) to the lower end face of the second groove, the second spring (143) is sleeved on the installation column (142) between the upper end face of the second boss and the upper end face of the second groove, and the compression stroke of the second spring (143) is shorter than that of the first spring (112);

a gear rack meshing section is arranged between the outer side wall of the transmission rod and the side wall of the channel, a winding drum (215) is coaxially arranged with the gear, a pull wire (153) is wound on the winding drum (215), a pull wire channel (152) which is used for the pull wire to penetrate and extends to the upper third of the transmission rod is arranged on the transmission rod (11), the other end of the pull wire (153) is embedded and fixed at the upper third of the transmission rod,

wherein, after the handle body (2) is inserted into a femoral medullary cavity, the channel (21) is communicated with the femoral medullary cavity (100), in the process that the transmission rod (11) moves downwards, the second spring (143) is compressed to a limit position earlier than the first spring (112), so that the transmission rod (11) transmits partial pressure stress applied to the inner side to the proximal end of the femur through the second spring (143) to reduce the pressure stress born by the transmission rod 11 in advance, meanwhile, the rack (151) drives the gear (214) to rotate anticlockwise, a pull wire (153) wound on the winding drum (215) pulls the upper third part of the transmission rod (11) downwards to relieve the upward tensile stress born by the transmission rod (11),

as the transmission rod (11) continues to move downwards, the first spring (112) is compressed to the limit position, the transmission rod (11) transmits the stressed pressure to the proximal femur (200) and the distal femur through the first spring (112) and the second spring (143), so that the whole femur bears the pressure,

when the transmission rod (11) moves upwards, after the first spring (112) is fully extended, the second spring (143) still transmits the pressure stress borne by the transmission rod (11) to the proximal end of the femur,

wherein, one or more sliding chutes (118) are arranged on the transmission rod (11) along the length direction of the transmission rod, corresponding to each sliding chute (118), a sliding vane (216) extends out of the channel (21) to the sliding chute, two side faces of the sliding vane (216) are attached to two inner side faces of the sliding chute (118), the length of the sliding chute (118) is longer than that of the sliding vane (216), so that the transmission rod can slide up and down and transmit torque to the proximal end of the femur,

the transmission rod is conical, the diameter of the transmission rod is gradually reduced from top to bottom, correspondingly, the channel of the handle body is also conical, the diameter of the channel is gradually reduced from top to bottom, and a plurality of cutting grooves (231) vertically extending to the lower end face of the handle body are formed in the lower portion of the handle body so as to enhance the elastic deformation capacity of the lower portion of the handle body.

2. Femoral stem according to claim 1, characterized in that a highly wear resistant rubber is provided on both sides of the runner (118) in contact with the sliding vane.

3. Femoral stem according to claim 1, wherein a third annular groove (120) is provided in said channel (21), wherein an annular sliding sleeve (220) is provided in said third annular groove, wherein a sliding track (221) is further provided in said third annular groove (120) along the length of said channel (21), wherein said sliding sleeve (220) is slidably mounted on said sliding track (221),

the annular sliding sleeve (220) extends out of the first annular flange (211) towards the radial inner side of the transmission rod, a third spring (119) is further arranged between the lower end face of the annular sliding sleeve (220) and the lower end face of the third annular groove (120), and the first spring (112) and the third spring (119) are sequentially compressed to bear pressure load.

4. The femoral stem according to claim 1, wherein a fourth groove (132) is further provided at the lower end of the transmission rod (11), a pressure-adjusting rod (130) is provided in the fourth groove (132), the upper end of the pressure-adjusting rod (130) has a fourth boss (133), the lower end of the fourth groove (132) is provided with a fifth boss (134) blocking the fourth boss (133),

a fourth spring (131) is provided between the upper end surface of the pressure regulating rod (130) and the upper end surface of the fourth groove (132).

5. The femoral stem according to claim 1, wherein one or more sealing rings or piston rings are further provided on the outer wall of the transmission rod to seal the channel.

6. The femoral stem of claim 1, wherein the taper of the drive link is between 1 ° and 3 °.

7. The femoral stem according to claim 1, wherein a detection unit is further provided at the lower end of the transmission rod for detecting the extension of the transmission rod beyond the lower end of the stem body and the pressure in the femoral cavity, the detection unit having a bluetooth module that is adapted to an external bluetooth device for transmitting detected data.