JP3342999B2 - Lag screw insertion direction determination device for intramedullary nail - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for determining the insertion direction of a lag screw of an intramedullary nail into a femur for use in an intramedullary fixation method for the treatment of a proximal femoral fracture in a human body.

[0002]

2. Description of the Related Art An intramedullary nail is composed of a rod-shaped nail having a proximal portion and a distal portion longer than the proximal portion with a middle bent portion, and a bone provided on the distal portion of the nail. Means for fixing the nail, a through hole obliquely penetrating the proximal portion near the bent portion of the nail, and a lag screw having a screw screwed into the bone head at the tip and inserted into the through hole. And is used for intramedullary fixation. For treatment of a proximal femoral fracture, a nail is driven into the lumen of the femur (the medullary cavity) from the proximal side, and then a lag screw is inserted through the femur and the through hole. Then, the screw at the tip of the lag screw is screwed toward the head of the femoral fracture.

[0003]

When a nail is driven into the inner cavity of the femur (medullary cavity), the driving depth is not always appropriate. If the driving depth is not proper, the lag screw inserted later through the through-hole of the nail cannot reach the proper position in the proximal part of the femur.

Therefore, an object of the present invention is to always insert the lag screw into the proper position of the proximal part of the femur after driving the nail of the intramedullary nail into the lumen of the femur (medullary cavity). It is an object of the present invention to provide a method and an apparatus for determining a lag screw insertion direction so that the lag screw can be inserted.

[0005]

SUMMARY OF THE INVENTION To solve the above-mentioned problems of the prior art, a method of determining a lag screw insertion direction according to the present invention is to hold a nail on a target device for holding the nail when driving into a femoral cavity. Then, while holding the nail in the target device, the nail is driven into the femoral cavity through the greater trochanter of the femur, and a base that can be inserted into and removed from the target device, and a lug when the base is inserted into the target device. Prepare a lag screw indicator consisting of an indicator rod that is oriented in a predetermined direction of insertion of the screw into the femur. The target instrument so that the indicator rod is in the correct insertion position with respect to the femur. Adjust the location, then the lag screw, characterized in that inserted into the femur using a target instrument.

Further, the lag screw insertion direction determining device of the present invention comprises a main body for detachably holding a base end of the lag screw, a support portion extending substantially along the lag screw held on the main body, and It has an insertion hole formed in the support portion and a base that can be inserted into and removed from the insertion hole, and when the base is inserted into the insertion hole of the support portion, the lag screw held in the main body is inserted into the femur. And a lag screw indicator having an indicator rod that is oriented outside of the body and oriented in a predetermined insertion direction.

The insertion hole of the support portion is a hole having a non-circular cross section, the base of the lag screw indicator is a rod having a cross section corresponding to the non-circular cross section, and the indicator rod is formed integrally with the base. It can be a rod that intersects it.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method and an apparatus for determining a lag screw insertion direction according to the present invention will be described below with reference to the drawings.

First, an example of the basic configuration of the intramedullary nail will be described. In FIG. 1, an intramedullary nail 1 includes a rod-shaped nail 2, a locking screw 3 as a means for engaging with a bone, and a lag screw, as is known.
4 and is used for the intramedullary fixation in the treatment of the proximal fracture of the femur 5 shown in FIG.

As shown in FIG. 2, the nail 2 has a bent portion 6 having a small angle in the middle, and a portion following the bent portion 6 (upper side in the figure) is a proximal portion 7 and the other side is a proximal portion 7. The lower portion (in the figure) is a distal portion 8 which is longer and narrower than the proximal portion 7. One side of the bent portion 6 is, of course, the convex side 6a. In the vicinity of the bent portion 6 of the proximal portion 7 of the nail 2, a through hole 12 for the lag screw 4 is formed obliquely with respect to the axis of the proximal portion 7. The inclination of the through-hole 12 is higher (as viewed) in the convex side 6a than in the concave side 6b. Through hole 12 for lag screw 4 of nail 2
The recessed portion 1 is located on the more distal portion 8 side and on the convex side 6a of the peripheral surface.
3 are formed. The concave portion 13 has a hollow shape so as to concave with a smooth curve. In the vicinity of the end of the distal portion 8 of the nail 2, a predetermined interval is formed, and the through screw holes 14 of the two locking screws 3 are formed so as to be orthogonal to the axis of the distal portion 8. As shown in FIG. 3, the nail 2 is fixed to the portion 5 a of the femur 5 by the locking screw 3 penetrating the portion 5 a of the femur 5 and penetrating the distal portion 8 of the nail 2. I have.

The lag screw 4 has a screw 16 at its tip.
Is formed, and the screw 16 is inserted into the through hole 12 of the nail 2 so that the screw 16 is on the proximal portion 7 side of the nail 2. The direction of insertion of the lag screw 4 into the through hole 12 is indicated by an arrow A.

As shown in FIG. 2, a set screw 9 for fixing the lag screw 4 inserted through the through hole 12 to the nail 2 is provided at an end of the proximal portion 7 of the nail 2. A plug 10 is screwed into the head of the screw 9. The tip 9a of the set screw 9 reaches the inside of the through hole 12 by screwing, and engages with the groove 4a formed in the longitudinal direction of the peripheral surface of the lag screw 4 inserted through the inside of the through hole 12 to prevent the rotation of the lag screw 4. And fix it to the nail 2. Thus, the lag screw 4 is fixed to the nail 2 as shown in FIG.

Next, how to use the above-described intramedullary nail 1 will be described. As shown in FIG. 4, the femur 5 is
9, lumen (medullary cavity) 20, major trochanter 20b and minor trochanter 2
0c and the like. Such a fracture occurring in the proximal portion of the femur 5 is most typically such as indicated at 18.

In order to temporarily fix such a fractured portion 18, an intramedullary nail 2 is driven into the lumen 20 of the femur 5.
To this end, the femur 5 in the state shown in the figure is first perforated by reaming as shown by an arrow B through the greater trochanter 20b, and the nail 2 is then passed through the perforation. It is driven toward the femoral cavity 20 so that the recess 13 on the convex side 6a faces the head 19, and reaches the position shown in FIG. In this case, since the concave portion 13 is formed on the convex side 6a of the through hole 12 of the nail 2,
The recessed portion 13 is used to insert the nail 2 into the bone portion 20a of the lumen 20.
The nail 2 can be driven into the lumen 20 smoothly and without damaging the bone portion 20a by preventing strong interference of the convex side 6a of the bent portion of the nail 2. When the nail 2 reaches the predetermined position in this manner, the nail 2 is fixed to the lumen 20 through the locking screw 3 to the distal portion 8 of the nail 2 through the portion 5a of the femur 5 as well. Then the femur 5
The lag screw 4 is inserted into the through-hole 12 of the nail 2 through a hole formed in the side wall of the nail 2, and the lag screw 4 is rotated by a tool (not shown) to screw the screw 16 into the head 19 and fix it. Thereafter, the proximal end of the lag screw 4 is pulled toward the non-screw side, and the head 19 side is pulled toward the distal side of the femur 5 so as to be brought into close contact with the fracture 18. Then, a set screw 9 is screwed into the end of the proximal portion 7 of the nail 2 as shown in FIG.
Is fixed to the nail 2. Next, the plug 10 is screwed. Thereby, the final fixed state shown in FIG. 3 is obtained. This state is maintained until the fracture 18 is joined. After the fracture 18 is completely cured, the intramedullary nail 1 is removed in the reverse order.

In order to attach an intramedullary nail as described above,
The target instrument and lag screw indicator described below are used. The patient P is first laid down and restrained on an operating table as shown in FIGS. In this example, a fracture has occurred in the left femur. Patient P
The upper part of the greater trochanter 20b of the left femur is first cut using a retractor 31, as shown at 30 in FIG. Next, FIG.
As shown in FIG.
Is inserted into the lumen (bone marrow cavity) 20. Subsequently, as shown in FIG. 9, the distal reamer 35 uses the guide rod 33, and then, as shown in FIG.
3, the reaming of the inside of the bone is performed by the proximal reamer 36. Next, the nail of the intramedullary nail 2 is driven into the femoral cavity 20.
This is performed using the target device 40 shown in FIG.

The target device 40 has a main body 42 having a handle 41, and a driving head 43 can be applied to the main body 42. At the front end of the main body 42, a holding portion 44 for holding the proximal portion 7 of the nail 2 is provided. Further, from the middle of the main body 42, the holding portion 4
A support portion 46 is integrally provided substantially along the nail 2 held by the support member 4. The support portion 46 has an insertion hole 48 having a non-circular (for example, quadrilateral) cross section. Further, an insertion portion 49 is formed in the support portion 46 near the insertion hole 48. In the illustrated state, the lag screw support sleeve 50 is held by the insertion portion 49, and the guide rod 51 is supported by the support sleeve 50.

For driving the intramedullary nail 2 into the femoral cavity 20, as shown in FIG. 11, while holding the proximal portion 7 of the nail 2 in the holding portion 44, the target instrument 4
12, the nail 2 is moved closer to the affected area as shown in FIG.
0, and then the nail 2 is driven deeply by the living head 43 as shown in FIG.

When the nail 2 is driven into the femoral cavity 20 at a predetermined depth, a lag screw indicator 60 as shown in FIG. 14 is attached to the target device 40 as shown in FIG. The lag screw indicator 60 basically has a T shape, and has a rod-shaped base portion 60a,
And an indicator rod 60b. The cross-sectional shape of the rod-shaped base 60 a is formed so as to correspond to the insertion hole 48 having a non-circular cross-section of the support part 46.
0a is non-rotatably insertable into the insertion hole 48.
The lag screw indicator 60 is designed such that the indicator rod 60b faces a predetermined direction when the base 60a is inserted into the insertion hole 48 as shown in FIG. That is, the indicator rod 60
The direction and the position of the target device 4 will be described later.
The position and the position of the lag screw 4 inserted through the inside of the support portion 49 toward the femoral head are completely matched.

When the nail 2 has been driven into the femoral cavity 20 and the lag screw indicator 60 has been mounted on the target device 40 as shown in FIG. 13, a transmission image crossing the femur and the indicator rod 60b is observed. That is, as shown in FIG. 5, for example, an X-ray irradiator 70 is installed above the affected part, an X-ray image generator 71 is installed below the affected part, and a transmission image of the affected part is generated in the image generator 71. Let it. Thereby, the positional relationship between the proximal part of the femur and the indicator rod 60b can be observed. In this case, as shown in FIG. 15, the target device 40 is moved from the X-ray irradiator 70 to the X-ray image generator 7.
It is necessary that the radiation path to 1 be safely 90 degrees.

As a result of observing the transmission image, if the positional relationship between the proximal part of the femur and the indicator rod 60b is proper as shown in FIG. 13, the next operation of driving the lag screw 4 is performed. On the other hand, when the positional relationship between the proximal part of the femur and the indicator rod 60b is not proper as shown in FIG. 16 (in FIG. 16, the indicator rod 60b is slightly displaced below the proximal part of the femur), the state shown in FIG. The nail 2 is moved in the longitudinal direction of the femur by slightly hitting the target device 40 with the striker bar 74 shown in FIG. Thus, the indicator rod 60b can be moved to an appropriate position as shown in FIG. All the confirmations are performed while observing the transmitted image of the image generating device 71.

When the proper position is confirmed, the next operation of driving the lag screw 4 is performed. This is performed by extruding the lag screw 4 using the wrench 75 as shown in FIG.

[0022]

As described above, by using the method for determining the insertion direction of the intramedullary nail lag screw according to the present invention, at the stage where the nail is driven into the femoral cavity, the femoral head of the lag screw that is driven thereafter. Since it is possible to reliably predict whether the position will be appropriate in the department,
It is possible to completely eliminate such a problem that the position of the lag screw is found to be incorrect after the lag screw is driven.

The intramedullary nail lag screw insertion direction determining apparatus of the present invention has the advantage of having an extremely simple structure in addition to the above-described effects. In particular, a lag screw indicator having an indicator rod has a simple structure, is inexpensive, and has a reliable operation.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of an intramedullary nail.

FIG. 2 is an exploded sectional view of a nail and a lag screw of an intramedullary nail.

FIG. 3 is an overall cross-sectional view showing a state where the intramedullary nail of FIG. 1 is applied to a fracture of a femur.

FIG. 4 is an explanatory view showing a fracture state of a femur.

FIG. 5 is an explanatory view showing a state of an intramedullary fixation operation using an intramedullary nail.

FIG. 6 is a plan view of FIG. 5;

FIG. 7 is a view showing a skin incision state before an operation.

FIG. 8 is an explanatory view showing insertion of a guide rod into a femoral lumen.

FIG. 9 is a diagram showing a first stage of reaming of a femur.

FIG. 10 is a diagram showing a second stage of reaming of the femur.

FIG. 11 is a perspective view of a target device.

FIG. 12 is a diagram showing a nail insertion operation using a target device.

FIG. 13 is an explanatory diagram showing one stage of a lag screw insertion direction determining method using a target device and a lag screw indicator.

FIG. 14 is a perspective view of a lag screw indicator.

FIG. 15 is an explanatory diagram showing a transmission observation state of an indicator rod and a femur of a lag screw indicator.

FIG. 16 is a diagram showing an adjustment operation when the result of transmission observation is inappropriate.

FIG. 17 is an explanatory view showing a lag screw driving operation after transmission observation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Intramedullary nail 2 Nail 4 Lag screw 5 Femur 9 Set screw 10 Plug 12 Through hole 16 Screw 18 Fracture part 19 Head part 20 Femoral lumen 33 Guide rod 40 Target device 41 Handle 42 Body 43 Driving head 44 Lag screw holding Part 46 support part 48 insertion hole 49 insertion part 60 lag screw indicator 60a base 60b indicator rod 70 X-ray irradiator 71 transmission image generator

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) A61B 17/58 315

Claims (2)

(57) [Claims] A main body for detachably holding a base end of the lag screw; a support portion extending substantially along the lag screw held by the main body; an insertion hole formed in the support portion; It has a base that can be inserted into and removed from the insertion hole, and when the base is inserted into the insertion hole of the support portion, the lag screw held in the main body is oriented in a predetermined direction of insertion into the femur and is inserted outside the body. A lag screw indicator having an indicator rod to be installed. 2. The insertion hole of the support portion is a hole having a non-circular cross section, the base of the lag screw indicator is a rod having a cross section corresponding to the non-circular cross section, and the indicator rod is integral with the base. None have intramedullary nail lag screw insertion direction determiner device according to claim 1, characterized in that the rod that intersects therewith.