Dynamic intramedullary nail with hybrid drive, dynamic intramedullary nail kit with magnetic actuator

Abstract

The object of the present invention is a dynamic intramedullary nail with hybrid drive, characterised in that it comprises a housing consisting of a proximal section and a distal section, and in that said housing comprises a magnetic rotor driven by an external magnetic field and an internal spring element that accumulates potential energy upon assembly, forming drive means for extending the nail in a telescopic manner.

Description

Technical Field

[0001] The object of the present invention is an intramedullary nail with variable length driven by a hybrid drive system. The implant can correct the length of the bone to be repaired. The extension or shortening of the nail can control the growth and repair rate of the bone. The hybrid drive used in the implant can achieve the required force during the extension process and fully control the nail length through an external device. Background Art

[0002] One way to address limb asymmetry is through surgical lengthening. Lengthening a limb with an external stabilizer is cumbersome and dangerous for the patient due to the size of the limb and the high potential for infection and other complications. Using an internal mechanism, an intramedullary nail, allows for painless rehabilitation while the internal implant does not interfere with the patient's daily function. In addition, the risk of wound infection is much lower.

[0003] Existing dynamic intramedullary nailing solutions are characterized by a single energy source for driving the implant elements. Dynamic intramedullary nailing with hybrid drive uses the mechanical energy accumulated in the elastic elements located inside the implant and the magnetic energy generated from the outside in a synchronized manner. The magnetic drive allows the introduction of energy from an external actuator to the device through the patient's tissue. The magnetic energy is converted inside the implant into mechanical energy for moving the mechanism. At the same time, the mechanical energy accumulated in the elastic elements with specific properties supports the working movement of the implant during an extended period. The forces generated by the elastic elements compensate for the mechanical interactions generated in the soft tissues (muscles, tendons and skin), which mitigate the magnetic drive.

[0004] The combination of both types of actuation allows for controlled lengthening during rehabilitation and minimizes the energy generated externally and passed through the patient's body. It also minimizes the size of the magnetic actuation within the implant, increasing the compactness and mechanical strength of the structure. The strength of the magnetic field generated by the external elements of the actuating nail mechanism is limited to an absolute minimum.

[0005] From the specification of Polish patent No. PL162850B1, a bone repair device is known for correcting the bone being repaired in the longitudinal direction, with play within a specified range and correction in the transverse direction. The device has a fixed and a movable jaw connected by a bolt. The jaw has a guide channel and an oval opening for mounting a bone implant. The channel and the opening are perpendicular to a plane passing through the longitudinal axis of the cylindrical guide.

[0006] From the specification of Polish patent PL226930B1, an expandable intramedullary nail for bone lengthening with a piezoelectric mechanism for bone lengthening is known, with a lengthening mechanism based on a piezoelectric actuator. The nail consists of a middle body, an upper body with a transverse opening and a longitudinal opening, and a pin, on which a bellows and a piezoelectric mechanism mounted on a flat surface of a lower groove are located, while the middle body has an upper groove and a lower groove, the upper groove and the lower groove having ratchet elements that can extend to the outside and are introduced into a groove in the middle body, the ratchet elements are based on a spring element, which has an opening and 12 openings on the entire periphery.

[0007] From the description of the Polish patent PL237952B1, a dynamic intramedullary nail is known, which is capable of angular correction, the nail being driven by an external magnetic field, in its structure, it has a rotating ring with an inclined front surface, the rotation of which causes the nail to bend, which provides the possibility of changing the angular orientation of the end of the bone being repaired. The construction of the nail is based on a telescopic extension mechanism that is able to independently rotate one end of the nail and is able to bend the nail. The drive of the nail extension and bending mechanism constitutes a magnetic transducer placed in the middle part of the nail. Due to the influence of the external magnetic field, the magnetic transducer independently rotates and drives the two nail mechanisms.

[0008] The device for lengthening long bones known from the specification of patent US5961553B has a lengthening mechanism based on an electric motor which rotates a lead screw of a linear actuator. The electric motor is connected to the lead screw via a reduction gear. The part of the implant comprising the cable drive and the piston engages the bone. The lengthening value is determined from the measured value of the number of revolutions of the lead screw. The system measuring the number of revolutions of the lead screw also identifies the direction of rotation.

[0009] From the specification of patent US5415660, an implantable limb extension nail driven by shape memory alloy is known, whose extension mechanism is based on shape memory alloy and ratchet assembly. The implant is formed by two telescopic cylinders connected to the bone. The element made of alloy moves a rod whose edge is adjusted to engage with the pawl of the ratchet assembly. The edge has a ledge that gradually narrows in one direction. This allows the rod to move in only one direction.

[0010] From the specification of patent US5976138B, a long bone distraction system is known, which displaces the middle fragment of a bone divided into three fragments (proximal, middle and distal). The proximal and distal fragments are connected to the sleeve of the implant, and the middle fragment can be displaced. The implant is equipped with an internally driven linear actuator that rotates a guide screw. The implant is engaged to the bone fragment by a screw.

[0011] The implant known from the specification of patent US2014 / 0236311A1 has the form of a linear actuator, two elements of which have been joined to two bone segments. The implant replaces the removed bone segment. The drive constitutes a piezoelectric motor connected to a gear that drives a lead screw. The rotary motion of the lead screw is converted into a linear motion of the shaft by means of a longitudinal groove and a screw placed in the housing and entering the groove. The drive is powered inductively by an external power source. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The subject matter of the invention is presented in more detail in the accompanying drawings, in which Figure 1 A schematic diagram of the structure of a dynamic intramedullary nail with hybrid drive is shown.

[0013] Figure 2 An intramedullary nail with hybrid drive and the influence of an external actuator and a magnetic field are shown. DETAILED DESCRIPTION

[0014] The essence of the dynamic intramedullary nail with hybrid drive according to the invention is that it has a structure based on a telescopic mechanism, which makes it possible to extend or shorten the implant.

[0015] A dynamic intramedullary nail (implant) consists of a skeleton (shell) and a drive located in the shell. The skeleton of the nail consists of the following parts: a proximal segment (1) having a first end and a second end for installation in the bone; and a distal segment (2) having a first end and a second end installed in the bone. The second ends of the two components are telescopically connected. The hybrid drive of the extension mechanism of the nail is a magnetic rotor (3) and a spring element (4) that act simultaneously and are placed in the central part of the nail. Due to the action of the external magnetic field generated by an external actuator (7), the magnetic rotor (3) rotates and drives the mechanical gear (5). The mechanical gear (5) drives the drive screw (6), which extends the nail by driving the distal segment (2) outward. The actuator (7) can have different structures. For example, it can be based on an electromagnet with a variable field, or use a rotating permanent magnet. The actuator (7) is a separate structure. Importantly, it is able to generate a variable magnetic field, thereby rotating the magnetic rotor.

[0016] The construction of a dynamic intramedullary nail with hybrid actuation enables actuation using both forces generated from spring elements enclosed within the implant and forces generated from an external energy source (via a magnetic field).

[0017] The dynamic intramedullary nail has in its structure a magnetic rotor (3) as a permanent magnet, which is moved by magnetic engagement of an external actuator (7). The movement of the magnetic rotor (3) causes the telescopic adjustment of the implant element through the additional elements of the drive system (mechanical gear (5) and drive screw (6)), thereby changing its length. The direction of movement of the external actuator (7) determines the extension or shortening of the implant. The mechanical gear (5) includes three gear assemblies, each of which consists of three wheels that operate by a rotational movement (planet) relative to a central wheel. The rotation of the shackle on which the planetary wheels are mounted drives the central wheel of the next set of wheels. The last shackle drives the drive screw. In the intramedullary nail with hybrid drive, there is also a spring element (4), which is deformed during the assembly process (nail production process); wherein this accumulated potential energy supports the nail extension movement. For example, the spring element (4) can be selected from a coil spring, a helical spring, a leaf spring and a gas spring. The essence of the spring element is to accumulate potential energy. The force generated by the spring element (4) reduces the reaction of the soft tissue of the limb and improves the effectiveness of the implant. The magnetic system consisting of an external magnetic actuator (7) and an internal magnetic rotor (3) can control the extension direction and speed of the nail. The nail can be used to stabilize bones after injury and to distract bones after osteotomy.

Claims

1. A dynamic intramedullary nail with hybrid drive, characterized in that: The invention comprises a housing composed of a proximal section (1) and a distal section (2), wherein the housing comprises a magnetic rotor (3) driven by an external magnetic field and an internal spring element (4) that accumulates potential energy during assembly, constituting a drive device for extending the intramedullary nail in a telescopic manner.

2. The dynamic intramedullary nail with hybrid drive according to claim 1, characterized in that: The proximal section (1) comprises a first end for mounting in a bone, and a second end.

3. The dynamic intramedullary nail with hybrid drive according to claim 1, characterized in that: The distal segment (2) comprises a first end for mounting in a bone, and a second end.

4. The dynamic intramedullary nail with hybrid drive according to any one of claims 1 to 3, characterized in that: The second end of the proximal section (1) is telescopically connected to the second end of the distal section (2).

5. The dynamic intramedullary nail with hybrid drive according to claim 1 or 3, characterized in that: A drive screw (6) extends from the proximal section (1) to the distal section (2), the drive screw (6) having a first end including a mechanical gear (5), and a second end of the drive screw (6) is located in the second end of the distal section (2).

6. The dynamic intramedullary nail with hybrid drive according to claim 1, characterized in that: The magnetic rotor (3) is actuated by an external magnetic field generated by an external magnetic actuator (7).

7. The dynamic intramedullary nail with hybrid drive according to claim 1 or 5, characterized in that: The drive screw (6) extends longitudinally through the spring element (4).

8. The dynamic intramedullary nail with hybrid drive according to claim 1, characterized in that: The driving device extends or shortens the length of the intramedullary nail according to the changing direction of the external magnetic field and by utilizing the potential energy accumulated in the internal spring element (4).

9. The dynamic intramedullary nail with hybrid drive according to claim 1, characterized in that: There is a magnetic rotor (3) which is moved by an external magnetic field generated from a magnetic actuator (7) and converted into movement of the intramedullary nail, while using forces generated from elements placed inside the implant to support this extension.

10. The dynamic intramedullary nail with hybrid drive according to claim 1, characterized in that: The mechanical gears (5) constitute a planetary gear set.

11. A kit comprising a dynamic intramedullary nail with hybrid drive according to claim 1, and a magnetic actuator (7), for use in bone distraction surgery.

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