LIGAMENT-TENSIONING DEVICE

• US 20090222089A1
• Filed: 10/18/2006
• Published: 09/03/2009
• Est. Priority Date: 10/18/2005
• Status: Active Grant

• Current Assignee: Smith & Nephew Orthopaedics Ag (Smith & Nephew PLC)
• Original Assignee: Smith & Nephew Orthopaedics Ag (Smith & Nephew PLC)
• Inventors: Stifter, Jan, Hauri, Thomas
• Granted Patent: US 9,216,097 B2
• Time in Patent Office: Days
• US Class Current: 623/13.130
• CPC Class Codes: A61B 17/025 Joint distractors
• CPC Class Codes: A61B 2017/0268 for the knee
• CPC Class Codes: A61F 2/0805 Implements for inserting tendons or ligaments
• CPC Class Codes: A61F 2/0811 Fixation devices for tendons or ligaments
• CPC Class Codes: A61F 2/38 for elbows or knees
• CPC Class Codes: A61F 2/4603 for insertion or extraction of endoprosthetic joints or of accessories thereof
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• CPC Class Codes: A61F 2/4684 Trial or dummy prostheses
• CPC Class Codes: A61F 2002/4661 for measuring thickness

Abstract

Ligament-tensioning device for activation of the ligament and/or capsule system in the implantation of a joint implant, having a distal bearing plate for bearing against a distal skeletal part and having first and second proximal bearing plates, each of which partially overlaps the distal bearing plate in a first in-use position, for bearing against a proximal skeletal part, and having means for relative displacement of the proximal bearing plates to increase their spacing from the distal bearing plate. The displacement means have a scissor-type guide means that supports the respective proximal bearing plate in the ventral-dorsal as well as the medial-lateral parallel position with respect to the distal bearing plate.

Claims

1-30. -30. (canceled)

31. A ligament-tensioning device for activation of the ligament and/or capsule system in the implantation of a joint implant, said device comprising:

a distal bearing plate adapted to bear against a distal skeletal part;

first and second proximal bearing plates, each of which at least partially overlaps said distal bearing plate when in a first in-use position, and adapted to bear against a proximal skeletal part;

a displacer for relative displacement of said proximal bearing plates away from the distal bearing plate so as to increase their spacing from the distal bearing plate; and

wherein the components of said ligament-tensioning device are dimensioned such that they can be accommodated between portions of the distal and proximal skeletal parts adjacent to the joint such that a joint capsule can be closed again after insertion of the ligament-tensioning device.

32. The device of claim 31, wherein the distal skeletal part is a tibia and the proximal skeletal part is a femur.

33. The device of claim 31, wherein the components include the distal bearing plate and the first and second proximal bearing plates.

34. The device of claim 31, wherein the displacer is an internal displacer.

35. The device of claim 31, wherein the displacer further comprises scissor-type guides that support the respective proximal bearing plates in a parallel position with respect to the distal bearing plate.

36. The device of claim 35, wherein the scissor-type guides are of torsionally stiff construction between the distal bearing plate and the respective proximal bearing plates to provide parallel guidance between the distal bearing plate and the proximal bearing plates that is precise in both the ventral-dorsal and the medial-lateral directions.

37. The device of claim .31, wherein said displacer comprises at least one spring element adapted to drive said proximal bearing plates, the spring element configured to store a drive energy while in a starting state in which said proximal bearing plates are spaced a minimum distance apart from said distal bearing plate, and to release said energy to increase the spacing when the device is actuated.

38. The device of claim 37, wherein said displacer has, assigned to each of said first and second bearing plates, a spring element for driving each of said proximal bearing plates.

39. The device of claim 37, wherein the at least one spring element is lockable.

40. The device of claim 37, wherein the at least one spring element comprises a compression spring element arranged in a region of overlap between said proximal and distal bearing plates.

41. The device of claim 40, wherein said at least one spring element comprises a spring selected from the group consisting of a steel helical spring and a titanium helical spring which has a form selected from the group consisting of a conical form and a double-cone form.

42. The device of claim 41, wherein said spring comprises a pitch indirectly proportional to a local winding diameter.

43. The device of claim 37, wherein said spring element comprises a flexural spring element.

44. The device of claim 43, wherein said spring element comprises a metal spring selected from the group consisting of a spiral spring and a leaf spring.

45. The device of claim 35, wherein said scissor-type guide comprises two scissor joints arranged close to opposite ends of said proximal bearing plate.

46. The device of claim 45, wherein the ends of the scissor joints are inserted in grooves in said distal and proximal bearing plates and one limb of each scissor joint or an end of one limb of each scissor joint is rotatably fixed within the plates by bearing pins or slide pegs extending perpendicular to a run of said groove.

47. The device of claim 46, wherein on another end of the limb or at a free end of another limb there is provided a slide peg for guiding the respective limb or end in a groove in said distal or proximal bearing plate, which groove is formed to match the slide peg.

48. The device of claim 45, wherein said scissor joints are joined to one another at least by a connecting rod mounted at the end of a limb of each scissor joint.

49. The device of claim 31, wherein said first and second proximal bearing plates each comprise an upper and a lower part, the lower part comprising a mounting adapted to mount at least one of said scissor-type guide and said spring element, the upper part being fixed releasably on the lower part to increase, as desired, the thickness of the bearing plate in question.

50. The device of claim 31, wherein the distal bearing plate or the first and second proximal bearing plates comprise releasable locking devices for independent locking of said first and second proximal bearing plates to said distal bearing plate at a minimum spacing and with respect thereto.

51. The device of claim 50, wherein said locking device has a hook pivotally mounted on the respective bearing plate and engaging in an opposing bearing plate, on which hook there is provided a first tool-engagement portion for actuation.

52. The device of claim 51, wherein the first tool-engagement portion is formed for engagement of a hex key.

53. The device of claim 51, wherein in the material of said first and second proximal bearing plates, in spatial association with the hook articulated on said distal bearing plate, there is formed an engagement portion for the hook.

54. The device of claim 51, wherein a first bearing peg of a scissor joint of the first or second proximal bearing plate projects beyond an outer edge thereof and is so arranged relative to the hook pivotally mounted on said distal bearing plate that it forms a counter-bearing of the locking device.

55. The device of claim 51, wherein a second bearing peg of a scissor joint of said first or second proximal bearing plates projects beyond the outer edge thereof and is so arranged relative to the hook pivotally mounted on said distal bearing plate that it forms a hinge pin thereof.

56. The device of claim 31, further comprising a cylindrical recess or other second tool-engagement portion, provided on the side edges of the distal bearing plate or of the first and second proximal bearing plates for engagement of a positioning tool.

57. The device of claim 37, having a spring element matched in spring constant to a predetermined tensioning force.

58. The device of claim 57, wherein the spring element provides a tensioning force that is substantially constant over its travel.

59. The device of claim 58, wherein the tensioning force is in the range of between 50 and 90 N.

60. The device of claim 58, wherein the tensioning force is approximately 70 N.

61. The device of claim 31, wherein the length/width ratio of the device generally matches the proportions of a resected portion of the adjacent skeletal part close to the joint.

62. The device of claim 31, comprising a configuration generally matched to a knee joint, the adjacent skeletal parts being a femur and a tibia.

63. The device of claim 61, wherein the length/width ratio is approximately 3/2 in accordance with that of a proximal resected tibia.

64. The device of claim 31, wherein at least one of the bearing plates is releasably coupleable to a sizer, which couples the proximal and distal skeletal parts in flexion to allow axial transmission from the one skeletal part to the other, taking account of the ligament tension.

65. The device of claim 64, having a connecting device for attaching the sizer on the distal bearing plate.

66. The device of claim 65, wherein the connecting device comprises two clip-like extensions on the distal bearing plate which, each engaging around a side edge of the proximal bearing plates, run to a base plate of the sizer.

67. A ligament-tensioning system comprising a ligament-tensioning device for activation of the ligament and/or capsule system in the implantation of a joint implant and a sizer to be attached to said device, said device comprising:

a distal bearing plate adapted to bear against a distal skeletal part;

at least one proximal bearing plate, which at least partially overlaps said distal bearing plate in a first in-use position, and is adapted to bear against a proximal skeletal part; and

a displacer for relative displacement of said proximal bearing plate relative to the distal bearing plate to increase their spacing from the distal bearing plate;

wherein components of said ligament-tensioning device, including the distal bearing plate and proximal bearing plate, are dimensioned so as to be entirely accommodated between portions of the distal and proximal skeletal parts adjacent to the joint in such a way that a joint capsule can be closed again after insertion of the ligament-tensioning device and a sizer.

68. The system of claim 67, wherein said ligament-tensioning device and said sizer are releasably coupled together and generally sized to match a knee joint implant.

69. The system of claim 67, wherein said ligament-tensioning device comprises two proximal bearing plates, each independently displaceable relative to the distal bearing plate.

70. The system of claim 67, wherein the proximal skeletal part is a femur and the distal skeletal part is a tibia.

71. A method of putting a ligament in tension comprising:

resecting a joint surface of at least one of a tibia and a femur;

inserting a ligament-tensioning device having at least one distal bearing plate and at least one proximal bearing plate into a space between the tibia and femur, the device inserted in a first compact configuration, at least one of said plates disposed adjacent to the resected joint surface;

displacing the at least one proximal bearing plate away from the at least one distal bearing plate so as to move the device into a second expanded configuration to increase a space between the tibia and the femur; and

closing a joint capsule connecting the tibia and femur to enclose the bearing plates.

72. The method of claim 71, wherein the joint capsule is closed prior to displacing the at least one proximal bearing plate away from the at least one distal bearing plate.

73. The method of claim 71, wherein the ligament-tensioning device fuirther comprises at least one displacer between the proximal and distal bearing plates, for displacing said proximal and distal bearing plates away from each other.

74. The method of claim 73, wherein the at least one displacer comprises a spring element.

75. The method of claim 73, further comprising the step of actuating the at least one displacer.

76. The method of claim 71, wherein the step of displacing comprises mechanically displacing.

77. The method of claim 73, wherein the at least one displacer comprises a plurality of displacers that can be activated independently.

78. The method of claim 71, wherein resecting comprises resecting both the femur and tibia.

79. The method of claim 73, wherein the at least one displacer is activated by the interaction of a hex key and an engagement portion of at least one bearing plate.

80. The method of claim 71, wherein the plates are positioned by a positioning tool that engages a cylindrical recess on at least one of the side edges of the at least one distal bearing plate and the at least one proximal bearing plate.

81. The method of claim 72, wherein prior to the closing step a sizer is releasably attached to a distal bearing plate after being inserted between the femur and tibia and configured to define a preferable size for the at least one proximal bearing plate.