Discretely adjustable hip-replacement trial

Patent metadata

Field	Value
Publication number	US-9439785-B2
Application number	US-201414296677-A
Country	US
Kind code	B2
Filing date	Jun 5, 2014
Priority date	Jul 15, 2013
Publication date	Sep 13, 2016
Grant date	Sep 13, 2016

Abstract

Hip replacement surgery (hip arthroplasty) includes implantation of a distal stem into a femur of a patient, and implantation of a proximal body to connect to the distal stem. A practitioner uses a “trial” or “provisional” to determine a suitable size and configuration for the implantable proximal body, then selects a suitable proximal body from a set of differently sized and shaped proximal bodies. The trial adjusts discretely, as opposed to continuously, and has discrete settings that correspond to the sizes and configurations available in the set of implantable proximal bodies. In some examples, the trials are provided as a kit of parts, where each part in the kit is adjustable for height (i.e., the length of the femur). The parts in the kit can have different, fixed, values for offset (i.e., the lateral distance of the femur to the center of the femoral head in the acetabulum).

First claim

The claimed invention is:

1. An adjustable trial for determining a suitable height of an implantable proximal body for hip replacement surgery, comprising:
a fixed portion configured to removably attach to an upper end of a stem at an upper end of a femur of a patient,
the fixed portion having a longitudinal axis extending in a vertical direction,
the fixed portion having an exterior surface,
the exterior surface including a plurality of indentations thereon at specified locations along the longitudinal axis;

an adjustable portion configured to slide vertically along the fixed portion; and
a movable element on the adjustable portion,
the movable element biased to contact the exterior surface of the fixed portion and configured to snap in a pivotal motion into at least some of the indentations as it slides along the fixed portion,
the movable element releasably locking the adjustable portion to the fixed portion when the movable element snaps into one of the indentations.

2. The adjustable trial of claim 1 , wherein the adjustable portion includes a hand-deployed release mechanism configured to retract the movable element from one of the indentations so as to unlock the adjustable portion from the fixed portion.

3. The adjustable trial of claim 1 , wherein for at least one of the plurality of indentations, an upper edge of the movable element and an upper edge of the indentation are shaped so that when the adjustable portion is locked to the fixed portion, applying an upward translational force to the adjustable portion releases the movable element from the indentation so as to unlock the adjustable portion from the fixed portion.

4. The adjustable trial of claim 1 , wherein for at least one of the plurality of indentations, a lower edge of the indentation and a lower edge of the movable element are shaped so that when the adjustable portion is locked to the fixed portion, applying a downward translational force to the adjustable portion does not release the movable element from the indentation and does not unlock the adjustable portion from the fixed portion.

5. The adjustable trial of claim 1 , wherein the plurality of indentations are arranged along a line parallel to the longitudinal axis.

6. The adjustable trial of claim 1 , wherein the adjustable portion and the fixed portion include complementary keying features that prevent rotation about the longitudinal axis between the adjustable portion and the fixed portion.

7. The adjustable trial of claim 1 , wherein the adjustable portion includes a bore sized and shaped to accommodate the exterior surface of the fixed portion, the bore and the exterior surface forming a clearance sufficient to allow the adjustable portion to slide vertically along the fixed portion.

8. The adjustable trial of claim 1 , wherein the adjustable portion is removable from the fixed portion over an upper end of the fixed portion.

9. The adjustable trial of claim 1 , further comprising a plurality of adjustable portions, each adjustable portion in the plurality having a different value of offset.

10. The adjustable trial of claim 1 , wherein the fixed portion includes a lower body, and further includes a lower bolt that attaches the lower body to the upper end of the stem, the lower bolt capable of being tightened and loosened from an upper end of the fixed portion, wherein at least one of the plurality of indentations extends over an exterior surface of the lower body.

11. An adjustable trial for determining a suitable height of an implantable proximal body for hip replacement surgery, comprising:
a fixed portion configured to removably attach to an upper end of a stem at an upper end of a femur of a patient,
the fixed portion having a longitudinal axis extending in a vertical direction,
the fixed portion having an exterior surface,
the exterior surface including a plurality of indentations thereon at specified locations along the longitudinal axis,
wherein the fixed portion includes a lower body,
wherein the fixed portion further includes a lower bolt that attaches the lower body to the upper end of the stem,
the lower bolt capable of being tightened and loosened from an upper end of the fixed portion,
wherein at least one of the plurality of indentations extends over an exterior surface of the lower body,
wherein the fixed portion further includes an upper extension, and further includes an upper bolt that attaches the upper extension to the lower body,
the upper bolt having a hollow interior sized to allow tightening and loosening of the lower bolt therethrough,
wherein at least one of the plurality of indentations is located on an exterior surface of the upper extension;

an adjustable portion configured to slide vertically along the fixed portion; and
a movable element on the adjustable portion,
the movable element biased to contact the exterior surface of the fixed portion and configured to snap into at least some of the indentations as it slides along the fixed portion,
the movable element releasably locking the adjustable portion to the fixed portion when the movable element snaps into one of the indentations.

12. A system of adjustable trials for determining a suitable height and offset of an implantable proximal body for hip replacement surgery, comprising:
a fixed portion configured to removably attach to an upper end of a stem at an upper end of a femur of a patient,
the fixed portion having a longitudinal axis extending in a vertical direction,
the fixed portion having an exterior surface,
the exterior surface including a plurality of indentations thereon at specified locations along the longitudinal axis; and

a plurality of adjustable portions,
each adjustable portion in the plurality configured to slide vertically along the fixed portion,
each adjustable portion in the plurality including a movable element,
each movable element biased to contact the exterior surface of the fixed portion and configured to snap in a pivotal motion into at least some of the indentations as it slides along the fixed portion,
each movable element releasably locking the respective adjustable portion to the fixed portion when the movable element snaps into one of the indentations, each adjustable portion in the plurality having a different value of offset.

13. The system of adjustable trials of claim 12 , wherein each adjustable portion includes a respective hand-deployed release mechanism configured to retract the respective movable element from one of the indentations and unlock the adjustable portion from the fixed portion.

14. The system of adjustable trials of claim 12 , wherein for at least one adjustable portion in the plurality and at least one of the plurality of indentations, an upper edge of the movable element and an upper edge of the indentation are shaped so that when the adjustable portion is locked to the fixed portion, applying an upward translational force to the adjustable portion releases the movable element from the indentation and unlocks the adjustable portion from the fixed portion.

15. The system of adjustable trials of claim 12 , wherein for at least one adjustable portion in the plurality and at least one of the plurality of indentations, a lower edge of the indentation and a lower edge of the movable element are shaped so that when the adjustable portion is locked to the fixed portion, applying a downward translational force to the adjustable portion does not release the movable element from the indentation and does not unlock the adjustable portion from the fixed portion.

16. The system of adjustable trials of

Assignees

• Zimmer Inc

Inventors

• Huddle Adam Christopher
• Krebs Robert D

Classifications

• A61F2002/3055

  for adjusting length · CPC title

• A61F2002/30505

  spring biased · CPC title

• A61F2/4684 Primary

  Trial or dummy prostheses · CPC title

• A61F2/3609

  Femoral heads or necks; Connections of endoprosthetic heads or necks to endoprosthetic femoral shafts (A61F2/3601 takes precedence) · CPC title

• A61F2002/3652

  Connections of necks to shafts · CPC title