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GB2639668A - Fixation pin - Google Patents

Fixation pin

Info

Publication number
GB2639668A
GB2639668A GB2404142.8A GB202404142A GB2639668A GB 2639668 A GB2639668 A GB 2639668A GB 202404142 A GB202404142 A GB 202404142A GB 2639668 A GB2639668 A GB 2639668A
Authority
GB
United Kingdom
Prior art keywords
cortex
drill
portion end
thread
fixation pin
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
GB2404142.8A
Other versions
GB202404142D0 (en
Inventor
Clark Damian
Gill Richie
Robinson James
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of Bath
Original Assignee
University of Bath
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University of Bath filed Critical University of Bath
Priority to GB2404142.8A priority Critical patent/GB2639668A/en
Publication of GB202404142D0 publication Critical patent/GB202404142D0/en
Priority to PCT/GB2025/050605 priority patent/WO2025196452A1/en
Publication of GB2639668A publication Critical patent/GB2639668A/en
Pending legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/84—Fasteners therefor or fasteners being internal fixation devices
    • A61B17/86—Pins or screws or threaded wires; nuts therefor
    • A61B17/8625—Shanks, i.e. parts contacting bone tissue
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/84—Fasteners therefor or fasteners being internal fixation devices
    • A61B17/86—Pins or screws or threaded wires; nuts therefor
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/84—Fasteners therefor or fasteners being internal fixation devices
    • A61B17/86—Pins or screws or threaded wires; nuts therefor
    • A61B17/8625—Shanks, i.e. parts contacting bone tissue
    • A61B17/863—Shanks, i.e. parts contacting bone tissue with thread interrupted or changing its form along shank, other than constant taper
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/84—Fasteners therefor or fasteners being internal fixation devices
    • A61B17/86—Pins or screws or threaded wires; nuts therefor
    • A61B17/8625—Shanks, i.e. parts contacting bone tissue
    • A61B17/8635—Tips of screws
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/60—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements for external osteosynthesis, e.g. distractors, contractors
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/84—Fasteners therefor or fasteners being internal fixation devices
    • A61B17/846—Nails or pins, i.e. anchors without movable parts, holding by friction only, with or without structured surface
    • A61B17/848—Kirschner wires, i.e. thin, long nails
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/84—Fasteners therefor or fasteners being internal fixation devices
    • A61B17/86—Pins or screws or threaded wires; nuts therefor
    • A61B17/8605—Heads, i.e. proximal ends projecting from bone
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/84—Fasteners therefor or fasteners being internal fixation devices
    • A61B17/86—Pins or screws or threaded wires; nuts therefor
    • A61B17/8645—Headless screws, e.g. ligament interference screws
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/39—Markers, e.g. radio-opaque or breast lesions markers
    • A61B2090/3983—Reference marker arrangements for use with image guided surgery
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B34/00—Computer-aided surgery; Manipulators or robots specially adapted for use in surgery
    • A61B34/20—Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis

Landscapes

  • Health & Medical Sciences (AREA)
  • Orthopedic Medicine & Surgery (AREA)
  • Surgery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Neurology (AREA)
  • Medical Informatics (AREA)
  • Molecular Biology (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Surgical Instruments (AREA)

Abstract

A bi-cortical fixation pin 10A comprising a drill portion end 20 having a drill tip portion 22 and a first tap body portion 24 having a first pitch thread 25 configured to cut a first thread through a first cortex. A securing portion 30 is adjacent the drill portion and is configured, when received in the first cortex, to modify the first thread to secure said securing portion. A fixation portion end 40 is adjacent the securing portion and is configured to receive a surgical device. The first pitch may be configured such that when rotated at drilling speed, it advances the drill portion along an axial direction at a first rate through the first cortex, and the securing portion is configured to prevent drill portion advancement when secured in the first cortex. The fixation portion may be threaded or unthreaded.

Description

FIXATION PIN
FIELD OF THE INVENTION
The present invention relates to a fixation pin used to secure a fixator to tissue.
BACKGROUND
Fixation pins are known. Fixation pins are typically used during surgical procedures. The fixation pin is inserted, typically into bone tissue, with one end being retained by the bone and another end used to receive a surgical device such as marker arrays for tracking bone position during robotic surgery or an external fixator used to hold a limb or other body part. However, existing fixation pins have shortcomings. Accordingly, it is desired to provide an improved fixation pin.
SUMMARY
According to a first aspect, there is provided a bi-cortical fixation pin, comprising: a drill portion end having a drill tip portion and first tap body portion having a first pitch thread configured to be engageable to cut a first thread through a first cortex; a securing portion adjacent the drill portion end and configured, when received within the first cortex, to modify the first thread to secure the securing portion within the first cortex; and a fixation portion end adjacent the securing portion and configured to receive a surgical device.
The first aspect recognizes that a problem with existing fixation pins is that they can be insufficiently well-secured to reliably hold the surgical device securely enough during surgery. Accordingly, a fixation pin is provided. The fixation pin may be a bi-cortical or two cortex fixation pin. The fixation pin may comprise a drill portion end or region. The drill portion end may have a drill tip portion or part. The drill portion end may have a first tap body portion or part. The first tap body portion may have a first pitch thread. That is to say that the first tap body portion may define a thread having a first pitch.
3o The first pitch thread may be configured or arranged, when received within a first cortex, to be engageable or operable to cut a first thread through the first cortex. The fixation pin may comprise a securing portion or part. The securing portion may be axially adjacent the drill portion end. The securing portion may be configured, when received within the first cortex, to modify the first thread to secure, fix, fasten or attach the securing portion within the first cortex. The fixation pin may comprise a fixation portion end or region. The fixation portion end may be axially adjacent the securing portion. The fixation portion end may be configured to receive a surgical device such as an external fixator, navigation or robotic array. In this way, by modifying the first thread to secure the securing portion within the first cortex, the fixation pin is retained in place securely.
The first pitch may be configured, when rotated at a drilling speed, to advance the drill portion end along an axial direction through the first cortex at a first axial rate and the securing portion is configured, when received within the first cortex at the drilling speed, to prevent the drill portion end being advanced along the axial direction at the first axial rate.
The first aspect also recognises that a problem with existing fixation pins is that when a drill portion end is configured with a drill tip portion and a first tap body portion, this can lead to cortex damage occurring. In particular, the drill portion end may be configured with the drill tip portion and first tap body portion in order to drill through a first cortex and then into a second cortex where the drill tip portion drills another hole in that second cortex and the first tap body portion is then used to secure the drill end portion into that second cortex. However, having already drilled through the first cortex, the presence of the first tap body portion and the first thread in that first cortex can mean that the fixation pin, and particularly the drill tip portion, is advanced axially due to the rotation of the fixation pin into the second cortex too quickly which can cause a fracture of the second cortex in the vicinity of the region where the drill tip portion impacts against the second cortex. Accordingly, the first pitch may be configured, when rotated at a drilling or operating speed, to advance or propel the drill portion along an axial direction through the first cortex at a first axial rate. The securing portion may be configured, when received within the first cortex at that same drilling speed, to prevent the drill portion being advanced or propelled along the axial direction at the first axial rate. In this way, once the drill portion end has moved through the first cortex and the securing portion is now received within the first cortex, the fixation pin is no longer advanced or propelled by the rotation of the fixation pin along the axial direction at the 3o first axial rate. This allows the axial speed of the drill tip portion to be controlled to help prevent such impact fractures occurring.
The securing portion may be configured, when received within the first cortex at the drilling speed, to prevent the drill portion end being advanced along the axial direction into a second cortex at the first axial rate. Accordingly, the securing portion may be configured to prevent, inhibit or stop the drill portion end from being advanced or propelled into the second cortex at the first axial rate during rotation of the fixation pin.
The securing portion may be configured without a first pitch thread. Accordingly, the absence or omission of the first pitch thread on the securing portion stops any forward axial movement when the securing portion is received in the first cortex.
The securing portion may comprise a non-threaded shank portion. Accordingly, providing a shank portion without a thread on the securing portion stops any forward axial movement when the securing portion is received in the first cortex.
The securing portion may be configured, when received within the first cortex at the drilling speed, to facilitate the drill portion end being advanced along the axial direction into the second cortex at a second axial rate which is lower than the first axial rate. Hence, the securing portion may be configured such that when it is received within the first cortex at the drilling speed, the drill portion end moves in the axial direction towards the second cortex at an axial rate which is slower than the first axial rate. This helps to reduce impact fractures to the second cortex.
The securing portion may be configured with a second tap body portion having a second pitch thread.
The second pitch thread may have a smaller pitch than the first pitch thread. In this way, for the same drilling or operating speed, the axial speed of the drill portion end when the second pitch thread engages with the first cortex is reduced compared to the axial speed when the first pitch thread is received in the first cortex. This helps to reduce impact fractures to the second cortex.
A major diameter of the second pitch thread may be larger than a major diameter of the first pitch thread. This helps to modify the first thread by cutting a second thread into the first cortex.
The securing portion may taper between the drill portion end and the fixation portion end.
The securing portion may enlarge radially between the drill portion end and the fixation portion end. Such enlargement helps to modify the first thread and improve the fit between the securing portion and the first cortex to help improve the fixing of the pin into the first cortex.
The securing portion may have a cross-sectional area which increases away from the drill portion end and towards the fixation portion end.
The cross-sectional area may increase to at least a major diameter of the first pitch thread.
The securing portion may comprise a reamer.
The securing portion may comprise at least one recess shaped to collect and convey at least one of tissue and fluid. Accordingly, tissue and/fluid may be removed to improve the fit between the external surface of the securing portion and the aperture cut into the first cortex.
The at least one recess may extend axially.
The securing portion may comprise a plurality of recesses distributed circumferentially around the securing portion.
The securing portion may be dimensioned to have an axial length which is longer than the drill portion end.
The securing portion may have an axial length dimensioned to be longer than a diameter of a medullary canal between the first cortex and the second cortex.
The securing portion may be dimensioned to have an axial length of greater than around 20mm.
The drill portion end may have an axial length dimensioned to prevent concurrent or 3o simultaneous engagement of drill portion end with both the first cortex and the second cortex. This helps to ensure that the drill portion end cannot be advanced or propelled into the second cortex at the first axial rate which helps to reduce impact fractures to the second cortex.
The drill portion end may have an axial length dimensioned to be shorter than a diameter of a medullary canal between the first cortex and the second cortex. This helps to ensure that the drill portion end cannot be advanced or propelled into the second cortex at the first axial rate which helps to reduce impact fractures to the second cortex.
The drill tip portion may have an axial length dimensioned to match a thickness of at least one of the first cortex and the second cortex. This helps to ensure that the drill portion end cannot be advanced or propelled into the second cortex at the first axial rate which helps to reduce impact fractures to the second cortex.
The drill tip portion has an axial length dimensioned to be shorter than a thickness of at to least one of the first cortex and the second cortex. This helps to ensure that the drill portion end cannot be advanced or propelled into the second cortex at the first axial rate which helps to reduce impact fractures to the second cortex.
The drill portion end may have an axial length of less than around 20mm.
The drill tip portion and the first tap body portion may be configured to overlap axially.
The drill tip portion may be configured to transition axially into the first tap body portion.
The first pitch thread may be configured to extend into flutes of the drill tip portion.
The drill tip portion may have a point angle of no more than around 90°.
The fixation portion end may be configured or dimensioned to extend from the first cortex when the drill portion end is received by the second cortex.
The fixation portion end may have an engagement structure shaped to receive a complementary engagement structure of the surgical device.
3o The surgical device may comprise an external fixator, navigation or robotic array.
The fixation portion end may be dimensioned to have an axial length which exceeds an axial length of the drill portion end and the securing portion.
The fixation portion end may have an axial length of greater than around 40mm.
According to a second aspect, there is provided a method, comprising: providing a drill portion end having a drill tip portion and first tap body portion having a first pitch thread configured to be engageable to cut a first thread through a first cortex; providing a securing portion adjacent the drill portion end and configured, when received within the first cortex, to modify the first thread to secure the securing portion within the first cortex; and providing a fixation portion end adjacent the securing portion and configured to receive a surgical device.
The method may comprise a method of configuring a bi-cortical fixation pin.
The method may comprise configuring the first pitch to advance the drill portion end along an axial direction through the first cortex at a first axial rate when rotated at a drilling speed and configuring the securing portion to prevent the drill portion end being advanced along the axial direction at the first axial rate when received within the first cortex at the drilling speed.
The method may comprise configuring the securing portion to prevent the drill portion end being advanced along the axial direction into a second cortex at the first axial rate when received within the first cortex at the drilling speed, The method may comprise configuring the securing portion without the first pitch thread.
The method may comprise configuring the securing portion with a non-threaded shank portion.
The method may comprise configuring the securing portion to facilitate the drill portion end being advanced along the axial direction into the second cortex at a second axial rate which is lower than the first axial rate when received within the first cortex at the 3o drilling speed.
The method may comprise configuring the securing portion with a second tap body portion having a second pitch thread.
The method may comprise configuring the second pitch thread to have a smaller pitch than the first pitch thread.
The method may comprise configuring a major diameter of the second pitch thread to be larger than a major diameter of the first pitch thread.
The method may comprise configuring the securing portion to taper between the drill portion end and the fixation portion end.
The method may comprise configuring the securing portion to enlarge radially between the drill portion end and the fixation portion end.
The method may comprise configuring the securing portion with a cross-sectional area which increases away from the drill portion end and towards the fixation portion end.
The method may comprise configuring the cross-sectional area to increase to at least a major diameter of the first pitch thread.
The method may comprise configuring the securing portion as a reamer.
The method may comprise configuring the securing portion with at least one recess shaped to collect and convey at least one of tissue and fluid.
The method may comprise configuring the at least one recess to extend axially.
The method may comprise configuring the securing portion with a plurality of recesses distributed circumferentially around the securing portion.
The method may comprise configuring the securing portion to be dimensioned to have an axial length which is longer than the drill portion end.
The method may comprise configuring the securing portion to have an axial length 3o dimensioned to be longer than a diameter of a medullary canal between the first cortex and the second cortex.
The method may comprise configuring the securing portion to be dimensioned to have an axial length of greater than around 20mm.
The method may comprise configuring the drill portion end to have an axial length dimensioned to prevent concurrent engagement of drill portion end with both the first cortex and the second cortex.
The method may comprise configuring the drill portion end to have an axial length dimensioned to be shorter than a diameter of a medullary canal between the first cortex and the second cortex.
The method may comprise configuring the drill tip portion to have an axial length io dimensioned to match a thickness of at least one of the first cortex and the second cortex.
The method may comprise configuring the drill tip portion to have an axial length dimensioned to be shorter than a thickness of at least one of the first cortex and the second cortex.
The method may comprise configuring the drill portion end to have an axial length of less than around 120mm.
The method may comprise configuring the drill tip portion and the first tap body portion to overlap axially.
The method may comprise configuring the drill tip portion to transition axially into the first tap body portion.
The method may comprise configuring the first pitch thread to extend into flutes of the drill tip portion.
The method may comprise configuring the drill tip portion to have a point angle of no 3o more than around 90°.
The method may comprise configuring the fixation portion end to extend from the first cortex when the drill portion end is received by the second cortex.
The method may comprise configuring the fixation portion end to have an engagement structure shaped to receive a complementary engagement structure of the surgical device.
The surgical device may comprise an external fixator, navigation or robotic array.
The method may comprise configuring the fixation portion end to be dimensioned to have an axial length which exceeds an axial length of the drill portion end and the securing portion.
The method may comprise configuring the fixation portion end to have an axial length of greater than around 40mm.
The method may comprise configuring the configuring a bi-cortical fixation pin to have the features of the bi-cortical fixation pin of the first aspect.
According to a third aspect, there is provided a method, comprising: drilling a first cortex with a bi-cortical fixation pin comprising a drill portion end having a drill tip portion and first tap body portion having a first pitch thread, a securing portion adjacent the drill portion end and a fixation portion end adjacent the securing portion; cutting a first thread through the first cortex with the first tap body portion; modifying the first thread with the securing portion to secure the securing portion within the first cortex; drilling a second cortex with the drill portion end to secure the drill portion end within the second cortex; and receiving a surgical device on the fixation portion end.
The second method may be a method of using a bi-cortical fixation pin.
The cutting the first thread may comprise, when rotated at a drilling speed, advancing the drill portion end along an axial direction through the first cortex at a first axial rate and the drilling the second cortex may comprise, when rotated at the drilling speed, preventing the drill portion end being advanced along the axial direction into the second cortex at the first axial rate.
The drilling the second cortex may comprise, when received within the first cortex at the drilling speed, facilitating the drill portion end being advanced along the axial direction into the second cortex at a second axial rate which is lower than the first axial rate.
The securing portion may be configured without the first pitch thread and the drilling the second cortex may comprise receiving the securing portion within the first cortex at the drilling speed to prevent the drill portion end being advanced along the axial direction into the second cortex at the first axial rate.
The securing portion may be configured with a non-threaded shank portion and the drilling the second cortex may comprise receiving the securing portion within the first cortex at the drilling speed to prevent the drill portion end being advanced along the axial direction into the second cortex at the first axial rate.
The securing portion may comprise a second tap body portion having a second pitch to thread smaller pitch than the first pitch thread and the drilling the second cortex may comprise receiving the securing portion within the first cortex at the drilling speed to facilitate the drill portion end being advanced along the axial direction into the second cortex at the second axial rate which is lower than the first axial rate.
The modifying may comprise deforming the first thread with the securing portion to secure the securing portion within the first cortex.
A major diameter of the second pitch thread may be larger than a major diameter of the first pitch thread and the modifying may comprise cutting a second thread with the second pitch thread as it advances along the axial direction within the first cortex to secure the securing portion within the first cortex.
The securing portion may taper between the drill portion end and the fixation portion end and the modifying may comprise deforming the first thread with the securing portion as it advances along the axial direction within the first cortex to secure the securing portion within the first cortex.
The securing portion may enlarge radially between the drill portion end and the fixation portion end and the modifying may comprise deforming the first thread with the 3o securing portion as it advances along the axial direction within the first cortex to secure the securing portion within the first cortex.
The securing portion may have a cross-sectional area which increases away from the drill portion end and towards the fixation portion end and the modifying may comprise deforming the first thread with the securing portion as it advances along the axial direction within the first cortex to secure the securing portion within the first cortex.
The cross-sectional area may increase to at least a major diameter of the first pitch thread and the modifying may comprise deforming the first thread with the securing portion as it advances along the axial direction within the first cortex to secure the securing portion within the first cortex.
The securing portion may comprise a reamer and the modifying may comprise deforming the first thread with the reamer as it advances along the axial direction within the first cortex to secure the securing portion within the first cortex.
io The securing portion may comprise at least one recess and the modifying may comprise collecting and conveying at least one of tissue and fluid with the reamer.
The securing portion may be dimensioned to have an axial length which is longer than the drill portion end.
The securing portion may have an axial length dimensioned to be longer than a diameter of a medullary canal between the first cortex and the second cortex.
The securing portion may be dimensioned to have an axial length of greater than 20 around 20mm.
The drill portion end may have an axial length dimensioned to prevent concurrent engagement of drill portion end with both the first cortex and the second cortex.
The drill portion end may have an axial length dimensioned to be shorter than a diameter of a medullary canal between the first cortex and the second cortex.
The drill tip portion may have an axial length dimensioned to match a thickness of at least one of the first cortex and the second cortex.
The drill tip portion may have an axial length dimensioned to be shorter than a thickness of at least one of the first cortex and the second cortex.
The drill portion end may have an axial length of less than around 120mm.
The drill tip portion and the first tap body portion may be configured to overlap axially.
The drill tip portion may be configured to transition axially into the first tap body portion.
The first pitch thread may be configured to extend into flutes of the drill tip portion.
The drill tip portion may have a point angle of no more than around 90°.
The fixation portion end may be configured to extend from the first cortex when the drill portion end is received by the second cortex.
The fixation portion end may have an engagement structure shaped to receive a complementary engagement structure of the surgical device.
The surgical device may comprise an external fixator, navigation or robotic array.
The fixation portion end may be dimensioned to have an axial length which exceeds an axial length of the drill portion end and the securing portion.
The method may comprise using a bi-cortical fixation pin having the features of the bicortical fixation pin of the first aspect.
Further particular and preferred aspects are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims.
Where an apparatus feature is described as being operable to provide a function, it will be appreciated that this includes an apparatus feature which provides that function or which is adapted or configured to provide that function.
3o BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will now be described further, with reference to the accompanying drawings, in which: Figure 1 illustrates a bi-cortical fixation pin according to one embodiment; and Figure 2 illustrates a bi-cortical fixation pin according to one embodiment.
DESCRIPTION OF THE EMBODIMENTS
Before discussing embodiments in any more detail, first an overview will be provided. Some embodiments provide a fixation pin having a drill portion end, a securing portion and a fixation portion. The drill portion end operates or functions to drill into tissue, such as bone, as the fixation pin is rotated. The drill portion end typically has a drill tip portion which drills a hole into the bone and a tap body portion which taps a thread in the hole in the bone in order to fix the drill portion end securely into the bone.
However, given that most uses of such a fixation pin involve drilling initially into a first cortex of the bone before entering the medullary canal, the presence of the tap body portion can propel the drill tip portion through the medullary canal as the fixation pin is rotated and can cause the drill tip portion to impact against a second cortex of the bone, causing fracture damage. As these fixation pins are typically inserted through the soft tissue the user is unable to see or evaluate the amount of damage that has occurred. When the procedure is complete the fixation pins are typically removed and if the damage has occurred, then this will leave a weakened region in the bone, which then can be an initiation point for a fracture. This can be a devastating complication for the patient and can require further procedures to fix the fracture. Also, it can be difficult to provide a secure enough fit in the hole in the first cortex. Accordingly, some embodiments have a securing portion adjacent the drill portion end. The securing portion is configured to prevent the fixation pin being propelled through the medullary canal at the same rate as it was propelled through the first cortex once the tap body portion has passed through the first cortex. This helps to reduce the speed at which the drill tip portion then approaches and engages with the second cortex, thereby reducing the risk of impact fracture. The reduced speed can be achieved by configuring the securing portion to either have no tap body portion at all or have a tap body portion which has a smaller pitch thread. The drill portion end can then advance into the second cortex and be retained by the tap body portion. The securing portion modifies the thread in the first cortex to improve the retention and secure the fit in the first cortex. This helps to provide a fixation pin which is well-secured within the bone 3o and which reduces the risk of fractures occurring.
Fixation Pin -151 Arrangement Figure 1 illustrates a bi-cortical fixation pin 10A according to one embodiment. In particular, Figure 1 shows a side view, an end view, a sectional view along the line B-B and an enlarged view of the region C. The bi-cortical fixation pin 10A is generally cylindrical and elongate in shape, extending along a central axis. The bi-cortical fixation pin 10A is formed from titanium, steel or other suitable surgical-grade material.
At one end is provided a drill portion end 20 which extends axially along a length of the bi-cortical fixation pin 10A. The drill portion end 20 terminates at an axially-adjoining securing portion 30. The securing portion 30 also extends axially along a length of the bi-cortical fixation pin 10A. The securing portion 30 terminates at an axially-adjoining fixation portion end 40. The fixation portion end 40 also extends axially along a length of the bi-cortical fixation pin 10A and is located at the other end of the bi-cortical fixation pin 10A from the drill portion end 20.
The drill portion end 20 has a drill tip portion 22 located at one end of the bi-cortical io fixation pin 10A and an axially-adjacent first tap body portion 24. The drill tip portion 22 typically comprises a four-facet drill tip 26 having a point angle of around 90 degrees. The drill tip portion 22 has flutes 28 which are defined by a helix having an angle of around 27 degrees. The drill tip portion 22 has an external diameter of typically around 2.6 millimetres. The axial length of the drill tip portion 22 is typically around 7.5 millimetres. The flutes 28 extend axially into the first tap body portion 24. The first tap body portion 24 has an external diameter of around 2.6 millimetres A pitch P1 of the thread 25 of the first tap body portion 24 is around 1.2 millimetres, with a thread depth of around 0.3 millimetres and a pitch radius of around 0.7 millimetres. The axial length of the first tap body portion 24 is typically around 7 millimetres and, as can be seen in Figure 1, the flutes 28 and the thread 25 inter-engage. Typically, adjacent the first tap body portion 24 is an unthreaded portion 27 having an axial length of around 7 millimetres.
Axially adjacent the drill portion end 20 is the securing portion 30. The securing portion 30 typically has a tapering portion 32. The tapering portion typically extends for an axial length of around 8 millimetres with around a 0.72 degree angle and enlarges from an initial diameter of around 2.6 millimetres nearest the drill tip portion 22 to an enlarged diameter of around 3.2 millimetres nearest the fixation portion end 40. Located within the securing portion 30 are a plurality (in this case, three) of recesses 3o 34 distributed circumferentially around the external surface of the securing portion 30.
The recesses 34 typically extend axially for a length of around 31 millimetres.
Axially adjacent the securing portion 30 is the fixation portion end 40. The fixation portion end is typically shaped (not shown) to match an engaging structure of a surgical device such as an external fixator, navigation or robotic array (not shown). The securing portion 30 typically has an axial length of around 60 millimetres.
The configuration and axial length of the drill portion end 20 is typically pre-configured so that the bi-cortical fixation pin 10A is not being propelled forwards by the thread 25 as it approaches the second cortex. In particular, the axial length of the drill portion 20 end is set such that the thread 25 has passed through the first cortex and is no longer engaged with the first cortex as the drill portion end 22 advances through the medullary canal towards the second cortex. Instead, the dimensions of the bi-cortical fixation pin 10A are configured so that the unthreaded portion 27 or the securing portion 30 is received within the first cortex and the bi-cortical fixation pin 10A can only be advanced towards the second cortex by pressure applied by the user. Also, the configuration and io dimensions of the securing portion 30 are selected to improve the fit of the bi-cortical fixation pin 10A in the hole created by the drill portion end 20 in the first cortex to improve the attachment of the securing portion 30 within the first cortex. This pre-configuring can occur in response to measurements of the cortexes and medullary canal and creating an appropriately-dimensioned bi-cortical fixation pin 10A or by selecting a suitable one of a selection of differently dimensioned bi-cortical fixation pins 10A.
In operation, the drill portion end 20 is advanced against a first cortex of a bone and the bi-cortical fixation pin 10A is rotated at a drilling or operating speed typically using a drill. The drill tip portion 22 cuts a hole into and through the first cortex, with the first tap body portion 24 cutting a first thread into the hole drilled into the first cortex. As the first thread is cut into the hole drilled into the first cortex, bi-cortical fixation pin 10A advances through the first cortex and into the medullary canal at a first axial rate. The thread 25 of the first tap body portion 24 then disengages from the first cortex and the bi-cortical fixation pin 10A ceases to advance at the first rate. With the bi-cortical fixation pin 10A still being rotated by the drill, the user can control the advance of the drill tip portion 26 axially towards a second cortex of the bone. As the drill tip 26 approaches the second cortex, the securing portion 30 engages with the hole in the first cortex and the tapering portion 32, together with the recesses 34, deforming the 3o thread that has been cut in the first cortex, removing any tissue or fluid within the hole in the first cortex and improving the contact between the first cortex and the external surface of the securing portion 30. Meanwhile, the drill tip portion 22 cuts a hole in the second cortex and the first tap body portion 24 begins to cut a thread into the second cortex. As this occurs, the torque resistance on the bi-cortical fixation pin 10A increases and the rotation is stopped. The bi-cortical fixation pin 10A is now safely and securely fixed to the bone in two locations. First, the drill portion end 20 is securely fixed into the second cortex, while the securing portion 30 is also securely held in the first cortex. Any surgical device can now be placed on the fixation portion end 40.
Figure 2 shows a bi-cortical fixation pin 10B according to one embodiment. This arrangement is identical to the arrangement shown in Figure 1, with the exception of the configuration of the securing portion 30B.
In this arrangement, the securing portion 30B is threaded to provide a second tap body portion having a second thread 35. The second thread 35 typically has a major io diameter larger than the major diameter of the thread 25. Also, the pitch P2 of the second thread 35 is smaller than the pitch P1 of the thread 25. The securing portion 30B may also be provided with a tapering portion and/or with recesses in a similar manner to that described above. The unthreaded portion 27 may be omitted, with the first tap body portion 24 and the second tap body portion being adjacent axially.
The configuration and axial length of the drill portion end 20 is typically pre-configured so that the bi-cortical fixation pin 10B is not being propelled forwards by the thread 25 as it approaches the second cortex. In particular, the axial length of the drill portion 20 end is set such that the thread 25 has passed through the first cortex and is no longer engaged with the first cortex as the drill portion end 26 advances through the medullary canal towards the second cortex. Instead, the dimensions of the bi-cortical fixation pin 10B are configured so that the securing portion 30B is received within the first cortex and the bi-cortical fixation pin 10B is propelled towards the second cortex by the second thread 35 at an axial speed which is slower than the axial speed caused by the thread 25 when rotated by the drill at the same drilling speed. Also, the configuration and dimensions of the securing portion 30B are selected to improve the fit of the bicortical fixation pin 10B in the hole created by the drill portion end 20 in the first cortex by expanding that hole and cutting a new fixing thread to improve the attachment of the securing portion 30B within the first cortex. This pre-configuring can occur in response 3o to measurements of the cortexes and medullary canal and creating an appropriately-dimensioned bi-cortical fixation pin 10B or by selecting a suitable one of a selection of differently dimensioned bi-cortical fixation pins 10B.
In operation, the drill portion end 20 is advanced against a first cortex of a bone and the bi-cortical fixation pin 10B is rotated at a drilling or operating speed typically using a drill. The drill tip portion 22 cuts a hole into and through the first cortex, with the first tap body portion 24 cutting a first thread into the hole drilled into the first cortex. As the first thread is cut into the hole drilled into the first cortex, the bi-cortical fixation pin 10B advances through the first cortex and into the medullary canal at a first axial rate determined by the rotation speed of the drill and the pitch P1 of the thread 25. The thread 25 of the first tap body portion 24 then disengages from the first cortex and the bi-cortical fixation pin 10B ceases to move forward at the first rate. With the bi-cortical fixation pin 10B still being rotated by the drill at the same rotation speed, the second thread 35 engages with the hole cut through the first cortex. As the drill tip 26 approaches the second cortex, the securing portion 30B deforms the thread that has been cut in the first cortex by cutting a second thread, removing any tissue or fluid within the hole in the first cortex and improving the contact between the first cortex and the external surface of the securing portion 30B. The drill tip 26 advances axially towards a second cortex of the bone at a slower speed than the first rate due to the smaller pitch P2 of the thread 35. The drill tip 26 cuts a hole in the second cortex and the first tap body portion 24 begins to cut a thread into the second cortex. As this occurs, the torque resistance on the bi-cortical fixation pin 10B increases and the rotation is stopped. The bi-cortical fixation pin 10B is now safely and securely fixed to the bone in two locations. First, the drill portion end 20 is securely fixed into the second cortex, while the securing portion 30B is also securely held in the first cortex. Any surgical indicators can now be placed on the fixation portion end 40.
Although a set of dimensions for the bi-cortical fixation pins are set out above, other dimensions are possible. In particular, some embodiments provide bi-cortical fixation pins with external diameters of generally around 4.0mm or 3.2mm. The total axial length of 3.2mm diameter bi-cortical fixation pins can range from around 70mm to 140mm, with preferred axial lengths of around 70mm, 110mm, 130mm or 140mm. The total axial length of 4.0mm diameter bi-cortical fixation pins can range from around 110mm to 170mm, with preferred axial lengths of around 110mm or 170mm. Some embodiments provide an axial length of the drill tip portion 22 ranging from around 1.8 to 4mm, with a preferred length of around 1.8mm. Some embodiments provide an 3o axial length of the first tap body portion 24 ranging from around 6mm to 14mm, with a preferred length of around 10.2mm. Some embodiments provide an axial length of the unthreaded portion 27 ranging from around 2mm to 8mm, with a preferred length of around 6mm. Some embodiments provide an axial length of the tapering portion 32 ranging from around 6mm to 12mm, with a preferred length of around 8mm. Some embodiments provide an axial length of the securing portion 30A, 30B ranging from around 20mm to 40mm around, with a preferred length of around 31mm.
Some embodiments provide bi-cortical fixation pins with specific cutting geometry of the tip to enhance purchase in the hard outer bone region, existing pins can often skid on the bone surface. Some embodiments provide bi-cortical fixation pins with a short threaded section just after the tip, this short section of self-cutting thread engages in the first cortex and then gives way to a smooth tapered section which prevents the pin from being accelerated into the bone as the rest of the pin passes through the first cortex. This threaded section is designed to engage into the second cortex. Some embodiments provide bi-cortical fixation pins with pressure relief scallops in the tapered section, these act to enhance the bone cutting at the edge of the scallops and provide io a channel for fluid/marrow to escape thus reducing the internal pressure in the bone Some embodiments provide bi-cortical fixation pins with a tapered section reaching the diameter equal to the outer diameter of the threaded section to enable secure fixing.
Testing of embodiments have shown that they perform as per the design intent: they are considerably easier to drill into hard bone, they do not accelerate the bone pin into the bone and do not cause damage to the bone on exiting the second cortex. In addition, using the new pins provided the user with direct haptic feedback on when the bone pin reached the second cortex.
Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiment and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.

Claims (23)

  1. CLAIMS1. A bi-cortical fixation pin, comprising: a drill portion end having a drill tip portion and first tap body portion having a first pitch thread configured to be engageable to cut a first thread through a first cortex; a securing portion adjacent said drill portion end and configured, when received within said first cortex, to modify said first thread to secure said securing portion within said first cortex; and a fixation portion end adjacent said securing portion and configured to receive a surgical device.
  2. 2. The bi-cortical fixation pin of claim 1, wherein said first pitch is configured, when rotated at a drilling speed, to advance said drill portion end along an axial direction through said first cortex at a first axial rate and said securing portion is configured, when received within said first cortex at said drilling speed, to prevent said drill portion end being advanced along said axial direction at said first axial rate.
  3. 3. The bi-cortical fixation pin of claim 1 or 2, wherein said securing portion is at least one of: configured, when received within said first cortex at said drilling speed, to prevent said drill portion end being advanced along said axial direction into a second cortex at said first axial rate; configured without said first pitch thread; configured, when received within said first cortex at said drilling speed, to facilitate said drill portion end being advanced along said axial direction into said second cortex at a second axial rate which is lower than said first axial rate; and configured with a second tap body portion having a second pitch thread.
  4. 4. The bi-cortical fixation pin of claim 3, wherein said second pitch thread has a 3o smaller pitch than said first pitch thread.
  5. 5. The bi-cortical fixation pin of claim 3 or 4, wherein a major diameter of said second pitch thread is larger than a major diameter of said first pitch thread.
  6. 6. The bi-cortical fixation pin of any preceding claim, wherein said securing portion comprises a non-threaded shank portion.
  7. 7. The bi-cortical fixation pin of any preceding claim, wherein said securing portion at least one of: tapers between said drill portion end and said fixation portion end; enlarges radially between said drill portion end and said fixation portion end; and has a cross-sectional area which increases away from said drill portion end and towards said fixation portion end.
  8. 8. The bi-cortical fixation pin of claim 7, wherein said cross-sectional area to increases to at least a major diameter of said first pitch thread.
  9. 9. The bi-cortical fixation pin of any preceding claim, wherein said securing portion comprises at least one of: a reamer; at least one recess shaped to collect and convey at least one of tissue and fluid; and plurality of recesses distributed circumferentially around said securing portion.
  10. 10. The bi-cortical fixation pin of claim 9, wherein said at least one recess extends axially.
  11. 11. The bi-cortical fixation pin of any preceding claim, wherein said securing portion is at least one of dimensioned to have an axial length which is longer than said drill portion end; dimensioned to have an axial length which is longer than a diameter of a medullary canal between said first cortex and said second cortex; and dimensioned to have an axial length of greater than around 20mm.
  12. 12. The bi-cortical fixation pin of any preceding claim, wherein said drill portion end 3o has at least one of: an axial length dimensioned to prevent concurrent engagement of drill portion end with both said first cortex and said second cortex; an axial length dimensioned to be shorter than a diameter of a medullary canal between said first cortex and said second cortex; and an axial length of less than around 20mm.
  13. 13. The bi-cortical fixation pin of any preceding claim, wherein said drill tip portion has at least one of: an axial length dimensioned to match a thickness of at least one of said first cortex and said second cortex; and an axial length dimensioned to be shorter than a thickness of at least one of said first cortex and said second cortex.
  14. 14. The bi-cortical fixation pin of any preceding claim, wherein said drill tip portion and said first tap body portion are configured to overlap axially.
  15. 15. The bi-cortical fixation pin of any preceding claim, wherein said drill tip portion is configured to transition axially into said first tap body portion.
  16. 16. The bi-cortical fixation pin of any preceding claim, wherein said first pitch thread is configured to extend into flutes of said drill tip portion.
  17. 17. The bi-cortical fixation pin of any preceding claim, wherein said drill tip portion has a point angle of no more than around 90°.
  18. 18. The bi-cortical fixation pin of any preceding claim, wherein said fixation portion end is configured to extend from said first cortex when said drill portion end is received by said second cortex.
  19. 19. The bi-cortical fixation pin of any preceding claim, wherein said fixation portion end has an engagement structure shaped to receive a complementary engagement structure of said surgical device.
  20. 20. The bi-cortical fixation pin of any preceding claim, wherein said fixation portion end is dimensioned to have an axial length which exceeds an axial length of said drill 3o portion end and said securing portion.
  21. 21. The bi-cortical fixation pin of any preceding claim, wherein said fixation portion end has an axial length of greater than around 40mm.
  22. 22. A method, comprising: providing a drill portion end having a drill tip portion and first tap body portion having a first pitch thread configured to be engageable to cut a first thread through a first cortex; providing a securing portion adjacent said drill portion end and configured, when received within said first cortex, to modify said first thread to secure said securing portion within said first cortex; and providing a fixation portion end adjacent said securing portion and configured to receive a surgical device.io
  23. 23. A method, comprising: drilling a first cortex with a bi-cortical fixation pin comprising a drill portion end having a drill tip portion and first tap body portion having a first pitch thread, a securing portion adjacent said drill portion end and a fixation portion end adjacent said securing portion; cutting a first thread through the first cortex with the first tap body portion; modifying said first thread with said securing portion to secure said securing portion within said first cortex; drilling a second cortex with said drill portion end to secure said drill portion end within said second cortex; and receiving a surgical device on said fixation portion end.
GB2404142.8A 2024-03-22 2024-03-22 Fixation pin Pending GB2639668A (en)

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GB2404142.8A GB2639668A (en) 2024-03-22 2024-03-22 Fixation pin
PCT/GB2025/050605 WO2025196452A1 (en) 2024-03-22 2025-03-21 Fixation pin

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US20040044345A1 (en) * 2002-08-28 2004-03-04 Demoss Richard Marshal Shallow penetration bone screw
US20080161814A1 (en) * 2006-12-28 2008-07-03 Mcallister Craig M Device and method for mounting an object on a bone
US8414629B2 (en) * 2009-11-20 2013-04-09 T. Hall Griffin Limiting radial preloads in securing an orthopedic fastener
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CN109363756A (en) * 2018-12-14 2019-02-22 北京大学第三医院 A kind of proximal femoral cross-locking intramedullary nail

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US11147602B2 (en) * 2017-05-04 2021-10-19 Warsaw Orthopedic, Inc. Spinal implant system and method
US10610243B2 (en) * 2017-10-09 2020-04-07 Acumed Llc System and method for installing a bicortical implant in bone
US12137941B2 (en) * 2021-12-23 2024-11-12 Orthofix S.R.L. Orthopedic cable bone transport device and bone transport system comprising said device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030105465A1 (en) * 2001-11-13 2003-06-05 Reinhold Schmieding Implant screw and washer assembly and method of fixation
US20040044345A1 (en) * 2002-08-28 2004-03-04 Demoss Richard Marshal Shallow penetration bone screw
US20080161814A1 (en) * 2006-12-28 2008-07-03 Mcallister Craig M Device and method for mounting an object on a bone
US20170304011A1 (en) * 2009-03-18 2017-10-26 Integrated Spinal Concepts, Inc. Image-guided minimal-step placement of screw into bone
US8414629B2 (en) * 2009-11-20 2013-04-09 T. Hall Griffin Limiting radial preloads in securing an orthopedic fastener
CN109363756A (en) * 2018-12-14 2019-02-22 北京大学第三医院 A kind of proximal femoral cross-locking intramedullary nail

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GB202404142D0 (en) 2024-05-08

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