Percutaneous minimally invasive bone fracture plate for fixing inner side of humeral shaft

Abstract

The invention discloses a percutaneous minimally invasive bone fracture plate for fixing the inner side of a humeral shaft, and belongs to the technical field of orthopedic medical instruments. The bone fracture plate is located on the inner side of the humerus, a perspective positioning point during reduction or a positioning point of a surgical robot can be designed to the outer side of the humerus, and the precision and convenience of the bone reduction operation of the orthopedic surgical robot are improved; due to the non-hole design of the middle section, the structural strength of a stress concentration area of the bone fracture plate is obviously improved, the firmness after fracture reduction is improved, meanwhile, bones and soft tissues near the fracture end are prevented from growing into nail holes, and the risk of secondary injury during later taking-out is reduced; the lower side of the middle portion of the bone fracture plate is designed to be of the outwards-protruding arc-shaped structure, the compression area on periosteum is reduced, the lower sides of the two end portions are designed to be of the inwards-protruding arc-shaped structure, the contact face is increased, and then the anti-rotation capacity is improved. The defects that an existing bone fracture plate for humeral shaft fracture is large in number of holes, uneven in stress, large in trauma and prone to injuring nerves are overcome.

Description

Technical Field

[0001] The present invention belongs to the technical field of orthopedic medical devices, and particularly relates to a percutaneous minimally invasive bone plate for medial fixation of the humeral shaft. Background Art

[0002] Fractures of the humeral shaft are common orthopedic diseases. Fractures of the humeral shaft account for 1% - 3% of all adult fractures and 20% of all humeral fractures. Traditional conservative treatments have some unsatisfactory situations, such as unstable position after reduction, repeated displacement, long-term swelling, etc. Moreover, patients cannot carry out daily activities during conservative external fixation, which is becoming increasingly unacceptable. Problems such as joint stiffness in the late recovery stage are also difficult to solve. Therefore, surgical internal fixation techniques are continuously improved in order to improve the fixation effect and the quality of life of patients, shorten the disuse time of adjacent joints, and reduce joint adhesions. However, for humeral shaft fractures that require surgical treatment, the ideal internal fixation technique is still controversial. Even though the intramedullary fixation technique has developed rapidly at present, fixation with various forms of bone plates is still the gold standard for clinical internal fixation treatment of humeral shaft fractures. However, conventional surgical methods have some defects, such as large surgical incisions and periosteal stripping, which cause greater damage to the soft tissue blood supply at the fracture end, a relatively high probability of nonunion, and easy deformation and fracture of the internal fixation steel plate. And various minimally invasive fixation methods are still in the stage of controversy due to the uncertainty of iatrogenic injuries. When performing reduction and internal fixation surgery on the position of humeral fractures, the existing steel plates have the following problems:

[0003] First, in the open reduction and internal fixation surgery through the lateral or posterolateral approach, the radial nerve that circumvents the posterior lateral side of the middle and distal segments of the humerus can basically not be avoided. Therefore, during the open reduction and internal fixation treatment of humeral fractures with a bone plate, it is mostly necessary to free the radial nerve and pass the bone plate under the radial nerve for fixation, which is likely to cause iatrogenic radial nerve injury. Moreover, the problems of inflammatory stimulation and injury caused by friction between the steel plate and the radial nerve are not easy to solve. When using an arched steel plate that crosses the radial nerve of the humerus or an S-shaped steel plate that bypasses the radial nerve, there are situations of increased soft tissue irritation, obvious changes in mechanical properties due to imperfect matching of the fracture morphology, and neither can deal with the common problem of radial nerve position variation.

[0004] Second, in the minimally invasive reduction and internal fixation surgery through the anterior side of the humerus, although the proximal anterior side of the humerus is relatively straight, the anteroposterior sides of the middle and distal segments are significantly less regular and smooth than the medial and lateral sides. The distal segment is a triangular prism with a relatively large inclination angle, and the morphological positions of the coronal fossa in the front and the olecranon fossa in the back of the distal end are irregular. It is difficult to shape and match when inserting the bone plate, and it is not conducive to the placement of the bone plate. This is likely to cause loss of fracture reduction after fixation, and the offset placement position is also likely to increase the irritation of surrounding tissues and secondary injuries.

[0005] Third, in various surgical procedures for humeral fractures, it is mostly necessary to bend the commonly used bone plates at present to achieve better bone matching. However, during the bending and adjustment process, the locking screw holes of steel or titanium plates are prone to deformation, resulting in the inability of the screws to be locked in place. Around the screw holes, the strength of the steel plate drops more significantly, affecting the stability of fixation and increasing the probability of fracture displacement and nonunion. Subsequently, due to insufficient internal fixation strength, the time and strength of rehabilitation exercises will also be affected.

[0006] Fourth, various minimally invasive internal fixation surgeries for the humerus all use the insertion method to place the steel plate. There are certain requirements for the fillet diameter and sharpness of the insertion end of the steel plate. If it is too sharp, the steel plate will be more likely to pierce through the myofascial membrane and deviate from the predetermined track, and it is also easy to damage important tissues; if it is too blunt, it will be difficult to separate the tissue space, resulting in difficult placement.

[0007] Fifth, in the internal fixation of humeral shaft fractures, the middle section of the steel plate is the area where the axial stress is most concentrated, while the axial stress at both ends is relatively small. The consistent strength of the entire length of the steel plate means that during actual use, the load on the middle section of the steel plate is closer to its fatigue limit. And the area near the screw junction closest to the fracture end is the area where the rotational stress is most concentrated. The uniformly distributed screw holes on the conventional steel plate make the screw holes closest to the fracture end for fixing screws the weakest area of the entire steel plate. Especially after bending, due to greater deformation near the screw holes, the steel plate fracture often occurs in the middle part and the bending part of the steel plate, especially near each empty screw hole in the middle part.

[0008] Sixth, in order to facilitate the compression and promotion of fracture healing at the fracture end, conventional straight steel plates are provided with multiple compression screw holes or compression locking screw holes. However, in many designs, such as in the general steel plate patent with the authorization announcement number CN2049115U, its compression holes are designed in the middle section of the steel plate. Through finite element analysis, this design will cause obvious stress concentration near the two compression holes close to the middle part. Considering that this section of the steel plate often needs to be bent and shaped, the local strength itself will also decrease significantly, so the risk of steel plate fracture will increase.

[0009] Seventh, most of the internal fixation for humeral shaft fractures needs to be removed after fracture healing. Since the minimally invasive implanted steel plate has no incision in the middle section of the humerus, it is not suitable to be incised during removal. However, during removal, the empty screw holes in the middle section of the humeral steel plate are often tightly grown into by new bone and cannot be directly removed; or due to the growth of more bone and soft tissues, the surrounding tissues are torn and damaged during removal.

[0010] In summary, the existing bone plates for humeral shaft fractures have the defects of many openings, uneven stress, large trauma, and easy nerve injury. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide a percutaneous minimally invasive bone plate for medial fixation of the humeral shaft in view of the deficiencies in the above-mentioned prior art. The design is novel and reasonable, the structure is simple, the trauma is small, and the safety is high.

[0012] To solve the above technical problems, the technical solution adopted by the present invention is:

[0013] A percutaneous minimally invasive bone plate for medial fixation of the humeral shaft, comprising a plate body;

[0014] Pressing holes, first locking holes, and second locking holes are sequentially arranged at both ends of the plate body; the area from one end of the plate body to the upper edge of the second locking hole is the first end portion, the area from the other end of the plate body to the lower edge of the first locking hole is the second end portion, and the remaining area is the middle portion; both sides of the first end portion linearly narrow from the inside to the outside longitudinally, both sides of the second end portion exponentially narrow from the inside to the outside longitudinally, and both sides of the middle portion remain unchanged;

[0015] The length of the plate body is determined according to the length of the humerus, and the length of the middle portion accounts for 65% - 67% of the total length of the plate body;

[0016] The thicknesses of the first end portion and the second end portion gradually decrease from the inside to the outside longitudinally, and the thickness of the middle portion remains unchanged; the cross-section of the middle portion is an arc-shaped structure with both the upper and lower sides protruding outward, and the cross-sections of the first end portion and the second end portion are arc-shaped structures with both the upper and lower sides protruding upward. The unchanged thickness of the middle portion enables the strength of the plate body to remain at a relatively high level after bending;

[0017] The two upper corners of the cross-section of the plate body adopt rounded corners with a radius of 2 mm, and the two lower corners adopt rounded corners with a radius of 0.5 mm;

[0018] The radius of the rounded corner at the edge of the first end portion is 0.5 mm; the edge of the second end portion is a quadratic curve, with the outermost radius being 1.5 mm and the innermost radius being 1 mm.

[0019] Further, the linear narrowing is expressed by the formula:

[0020] Y 1 = tan M°×x 1

[0021] where y 1 is the lateral narrowing amount on one side of the first end portion, x 1 is the longitudinal length from the second locking hole to this end portion, and M° is an angular value, M° ∈ [5.60°, 6.00°].

[0022] Further, the exponential narrowing is expressed by the formula:

[0023]

[0024] Among them, y 2 is the lateral narrowing amount on one side of the second end, and x 2 is the longitudinal length from the lower edge of the first locking hole to this end.

[0025] Furthermore, the thickness at the central axis of the plate body cross-section is greater than the thickness of both side edges.

[0026] Furthermore, the thickness of the central axis is 4 mm.

[0027] Furthermore, the arc radii of the arc-shaped structures are all 30 mm.

[0028] Furthermore, both the first locking hole and the second locking hole adopt standard φ4.5 mm locking screw holes, and the pressurizing hole adopts a 10×5.0 mm sliding pressurizing screw hole; the center distance between the first locking hole and the second locking hole is 21 mm, and the center distance between the first locking hole and the pressurizing hole is 19 mm.

[0029] Furthermore, it further includes a drill bit guide. The guide has a central hole and an eccentric hole, and the edge of the eccentric hole of the guide is tangent to the edge of the pressurizing hole.

[0030] The present invention has the following advantages compared with the prior art:

[0031] 1. The bone plate of the present invention anatomically avoids the positions where important nerves and blood vessels pass, reducing the risk of iatrogenic injury to the radial nerve during the implantation of the bone plate;

[0032] 2. In the present invention, the bone plate is located on the medial side of the humerus, and the fluoroscopy positioning point during reduction or the positioning point of the surgical robot can be designed on the lateral side of the humerus, facilitating fluoroscopy positioning and reduction, and improving both the accuracy and convenience of the bone reduction surgery with the cooperation of the orthopedic surgical robot;

[0033] 3. The design without holes in the middle section significantly improves the structural strength of the stress concentration area of the bone plate, enhances the firmness after fracture reduction, and at the same time avoids the growth of bone and soft tissues near the fracture end into the nail holes, reducing the risk of secondary injury during later removal;

[0034] 4. The lower side of the middle part of the bone plate is designed as an outwardly convex arc-shaped structure, reducing the compression area on the periosteum, while the lower sides of both ends are designed as inwardly convex arc-shaped structures, increasing the contact surface, thereby improving the anti-rotation ability;

[0035] 5. The pressurizing holes at the first end and the second end can provide different pressurizing amplitudes, facilitating fine adjustment of the bone plate;

[0036] 6. The edges of both the first end and the second end are curved surfaces, which is beneficial for separating soft tissues when inserting the bone plate and can also reduce the damage caused by accidental insertion into muscle tissues due to excessive sharpness.

[0037] The technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0038] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the percutaneous minimally invasive bone plate for medial fixation of the humeral shaft according to the present invention;

[0039] Figure 2 It is a schematic front view structure diagram of an embodiment of the percutaneous minimally invasive bone plate for medial fixation of the humeral shaft according to the present invention;

[0040] Figure 3 It is a schematic right view structure diagram of an embodiment of the percutaneous minimally invasive bone plate for medial fixation of the humeral shaft according to the present invention;

[0041] Figure 4 It is a schematic cross-sectional structure diagram of the middle part of an embodiment of the percutaneous minimally invasive bone plate for medial fixation of the humeral shaft according to the present invention;

[0042] Figure 5 It is a schematic structure diagram of the guide of an embodiment of the percutaneous minimally invasive bone plate for medial fixation of the humeral shaft according to the present invention;

[0043] Figure 6 It is a schematic cross-sectional structure diagram of the end part of an embodiment of the percutaneous minimally invasive bone plate for medial fixation of the humeral shaft according to the present invention;

[0044] Description of the Reference Numerals:

[0045] 1. Middle part; 2. First end; 3. Second end; 4. Compression hole; 5. First locking hole; 6. Second locking hole; 7. Arc structure; 8. End edge of the first end; 9. End edge of the second end; 10. Plate body; 11. Guide; 12. Central hole; 13. Eccentric hole. Detailed Embodiment

[0046] An embodiment of the percutaneous minimally invasive bone plate for medial fixation of the humeral shaft:

[0047] As Figures 1-6 shown, the percutaneous minimally invasive bone plate for medial fixation of the humeral shaft includes an integrally formed plate body 10. Specifically, the length, width, and thickness of the plate body 10 are designed.

[0048] First, pressure holes 4, first locking holes 5, and second locking holes 6 are sequentially arranged at both ends of the plate body 10. Both the first locking hole 5 and the second locking hole 6 are standard φ4.5mm locking screw holes, and the pressure hole 4 is a 10×5.0mm sliding pressure screw hole. The above screws are all φ4.5mm cortical bone screws. When a small range of fracture gap adjustment is required, it can be achieved through one pressure hole 4. When a large range of fracture gap adjustment is required, it can be achieved by the cooperation of the two pressure holes 4 at both ends of the plate body 10.

[0049] After the first locking hole 5 and the second locking hole 6 are combined with the locking screws, an angular stable structure is formed between the screws and the bone plate, playing an important role in holding and fixing. This structure provides more stable fixation for the fracture site, effectively reducing the micro-movement of the fracture ends, thereby facilitating fracture healing.

[0050] After the pressure hole 4 is matched with the pressure screw, the fracture ends can be brought closer to each other to generate a pressure effect, thereby promoting fracture healing. Specifically, the pressure screw has an adjustable pressure effect within the range restricted by the sliding groove and provides temporary fixation during the operation. When the locking screws are inserted, the function of the pressure screw will change accordingly.

[0051] In some surgeries, preoperative pre-shaping or manual bending operations will be performed on the bone plate. When bending and shaping the bone plate in this application, it is recommended that the shaping area be locked in the non-perforated area.

[0052] The shaping area is preferably designed in the non-perforated area in the middle. In this way, the strength of the steel plate decreases less during bending and does not affect the locking function of the locking holes. The locking hole spacing is selected based on the results of finite element analysis. If the spacing is too small, it will lead to a decrease in the strength of the steel plate and stress concentration. If the spacing is too large, the length of the perforated areas at both ends will be too long, and a longer incision will be required during the operation to ensure that the fixing screws can be screwed in. The center distance between the first locking hole 5 and the second locking hole 6 is 21mm, and the center distance between the first locking hole 5 and the pressure hole 4 is 19mm.

[0053] For the convenience of description, the plate body 10 is divided into three parts. The area from one end of the plate body 10 to the upper edge of the second locking hole 6 is the first end part 2, the area from the other end of the plate body 10 to the lower edge of the first locking hole 5 is the second end part 3, and the remaining area is the middle part 1.

[0054] The two sides of the plate body 10 adopt an asymmetric narrowing method. Specifically, the two sides of the first end part 2 are linearly narrowed longitudinally from the inside to the outside, the two sides of the second end part 3 are exponentially narrowed longitudinally from the inside to the outside, and the two sides of the middle part 1 remain unchanged. First, the narrowing of both the first end part 2 and the second end part 3 can ensure the convenient insertion of the bone plate. Through the exponential narrowing of the second end part 3, the width near the first locking hole 5 and the second locking hole 6 where the stress is relatively concentrated decreases more gently, so as to maintain better mechanical strength.

[0055] Among them, the linear narrowing is expressed by the formula:

[0056] y 1 = tan M° × x 1

[0057] Among them, y 1 is the lateral narrowing amount on one side of the first end, x 1 is the longitudinal length from the second locking hole to this end, and M° is the angle value, M° ∈ [5.60°, 6.00°].

[0058] The above exponential narrowing is expressed by the formula:

[0059]

[0060] Among them, y 2 is the lateral narrowing amount on one side of the second end, x 2 is the longitudinal length from the lower edge of the first locking hole to this end.

[0061] The length of the plate body 10 is determined according to the length of the humerus. The length of the middle part 1 accounts for 65% - 67% of the total length of the plate body; there are no designed holes on the middle part 1. Through the design without holes, stress concentration is avoided to disperse stress. Preferably, the length of the middle part 1 accounts for 66% of the total length of the plate body.

[0062] The thicknesses of the first end 2 and the second end 3 gradually decrease from inside to outside longitudinally, and the thickness of the middle part 1 remains unchanged; this facilitates the operation of inserting the bone plate, and at the same time can ensure the strength of the plate body 10.

[0063] The gradually narrowing and thinning design of the first end 2 and the second end 3 facilitates the implantation of the bone plate, reduces the probability of mis-penetration, and reduces the excessive irritation of the bone plate to soft tissues such as the medial muscles, blood vessels and nerves of the humerus.

[0064] The cross-section of the middle part 1 is an arc-shaped structure 7 with both upper and lower sides protruding outward, and the cross-sections of the first end 2 and the second end are arc-shaped structures 7 with both upper and lower sides protruding upward. By designing the lower side of the middle part 1 into a protruding arc-shaped structure 7, the contact area between the bone plate and the periosteum of the humeral shaft is reduced; thereby reducing the compression area on the periosteum. The fitting of the plate body 10 with the bone surface of the humerus is realized through the arc-shaped structure 7 with protruding phases, so that the angle between the planes where the first end 2 and the second end 3 are located matches the medial shape of the humerus.

[0065] The two corners on the upper side of the cross section of the plate body 10 are chamfered with a radius of 2 mm, and the two corners on the lower side are chamfered with a radius of 0.5 mm. The end edge 8 of the first end has a chamfer radius of 0.5 mm; the end edge 9 of the second end is a quadratic curve, with an outermost radius of 1.5 mm and an innermost radius of 1 mm. The chamfered design makes the edge of the bone plate more rounded, reducing the stimulation to the surrounding soft tissue.

[0066] The thickness of the cross section of the plate body 10 at the center axis is greater than the thickness of the two side edges. The thickness of the center axis is 4 mm. The arc radius of the arc structure 7 is 30 mm.

[0067] In order to facilitate the operation, the plate body 10 is also provided with a drill guide 11 , which has a central hole 12 and an eccentric hole 13 , and the edge of the eccentric hole 13 of the guide 11 is tangent to the edge of the pressurized hole 4 .

[0068] Taking the humeral shaft length of 25 cm to 30 cm as an example, the length of the plate body 10 is designed to be 200 mm, the width of the middle portion 1 is 13.2 mm, the width of the first end 2 and the second end 3 near the middle portion 1 is 13.2 mm, and the width away from the middle portion 1 is 9 mm. The thickness of the middle portion 1 is 4 mm.

[0069] The process of using the bone plate is as follows: the skin at the distal and proximal ends of the humerus is cut about 3 cm each, and after separating the tissues, the bone plate is inserted from the distal incision of the humerus. The first end 2 of the plate body 10 is inserted first. The first end 2 is linearly narrowed and is more suitable as an insertion end. After the bone plate is pushed proximally close to the periosteum, the fracture fragment is reset by robot or manual operation, and the second end 3 of the shaped bone plate is fitted to the proximal bone cortex of the humerus, and the first end 2 is fitted to the surface of the distal bone cortex of the humerus. After determining the length and force line, the guide 11 is used to select the central hole 12 or the eccentric hole 13 channel according to the specific situation of the fracture, and the cortical screw is driven into the pressure hole 4; the fracture ends are reset by fluoroscopy until they are reset in place, and the two cortical bone screws at both ends of the plate body 10 are properly tightened to ensure stable fixation of the fracture ends. If it is necessary to apply pressure to the fracture ends, the pressure can be adjusted at this time, and then a conventional locking guide 11 is used to drill four locking screws into the first locking hole 5 and the second locking hole 6, and tighten each locking screw.

[0070] If the humerus is found to have a large morphological variation during surgery, bending and shaping should be performed in the middle part 1 as much as possible to avoid iatrogenic fractures, internal fixation failure, and other problems, and to improve the stability of the plate and bone after fixation.

[0071] In addition, the surgical position of the bone plate is on the medial side, leaving the vacant lateral side more convenient for conventional surgical fluoroscopy positioning. Using the lateral surface of the humerus as the positioning point during the reduction by the surgical robot, it is more convenient when cooperating with the orthopedic surgical robot for bone reduction surgery, which is beneficial to shortening the operation time.

[0072] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent structural changes made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A percutaneous minimally invasive bone plate for fixation of the medial side of the humeral shaft, characterized in that: It comprises a plate body (10); Both ends of the plate body (10) are provided with a pressurizing hole (4), a first locking hole (5), and a second locking hole (6) in sequence; the area from one end of the plate body (10) to the upper edge of the second locking hole (6) is the first end (2), the area from the other end of the plate body (10) to the lower edge of the first locking hole (5) is the second end (3), and the remaining area is the middle part (1); the two sides of the first end (2) are linearly narrowed from the inside to the outside along the longitudinal direction, the two sides of the second end (3) are exponentially narrowed from the inside to the outside along the longitudinal direction, and the two sides of the middle part (1) remain unchanged; The length of the plate body (10) is determined according to the length of the humerus, and the length of the middle part (1) accounts for 65% to 67% of the total length of the plate body; The thickness of the first end portion (2) and the second end portion (3) gradually decreases from the inside to the outside in the longitudinal direction, and the thickness of the middle portion (1) remains unchanged; the cross section of the middle portion (1) is an arc-shaped structure (7) with both upper and lower sides bulging outwards, and the cross section of the first end portion (2) and the second end portion is an arc-shaped structure (7) with both upper and lower sides bulging upwards, and the thickness of the middle portion (1) remains unchanged, so that the strength of the plate body (10) is still maintained at a high level after being bent; The two corners on the upper side of the cross section of the plate body (10) are chamfered with a radius of 2 mm, and the two corners on the lower side are chamfered with a radius of 0.5 mm; The end edge (8) of the first end has a rounded corner radius of 0.5 mm; the end edge (9) of the second end is a quadratic curve, the outermost radius is 1.5 mm, and the innermost radius is 1 mm.

2. A percutaneous minimally invasive bone plate for medial fixation of the humeral shaft according to claim 1, characterized in that: The linear narrowing is expressed by the formula: y1=tan M°×x1 Wherein, y1 is the lateral narrowing amount of one side of the first end, x1 is the longitudinal length from the second locking hole to the end, and M° is the angle value, M°∈[5.60°, 6.00°].

3. A percutaneous minimally invasive bone plate for medial fixation of the humeral shaft according to claim 1, characterized in that: The index narrowing is expressed by the formula: Among them, y2 is the lateral narrowing amount of one side of the second end, and x2 is the longitudinal length from the lower edge of the first locking hole to the end.

4. A percutaneous minimally invasive bone plate for medial fixation of the humeral shaft according to claim 1, characterized in that: The thickness of the cross section of the plate body (10) at the center axis is greater than the thickness at the edges on both sides.

5. A percutaneous minimally invasive bone plate for medial fixation of the humeral shaft according to claim 4, characterized in that: The thickness of the central axis is 4 mm.

6. A percutaneous minimally invasive bone plate for medial fixation of the humeral shaft according to claim 1, characterized in that: The arc radius of the arc structure (7) is 30 mm.

7. A percutaneous minimally invasive bone plate for medial fixation of the humeral shaft according to claim 1, characterized in that: The first locking hole (5) and the second locking hole (6) both use standard φ4.5 mm locking screw holes, and the pressurizing hole (4) uses a 10×5.0 mm sliding pressurizing screw hole; the center distance between the first locking hole (5) and the second locking hole (6) is 21 mm, and the center distance between the first locking hole (5) and the pressurizing hole (4) is 19 mm.

8. A percutaneous minimally invasive bone plate for medial fixation of the humeral shaft according to claim 1, characterized in that: The drill bit guide (11) is also included. The guide (11) has a central hole (12) and an eccentric hole (13). The edge of the eccentric hole (13) of the guide (11) is tangent to the edge of the pressure hole (4).

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