Modular femoral prosthesis with on-axis junction

• US 7,776,098 B2
• Filed: 10/12/2006
• Issued: 08/17/2010
• Est. Priority Date: 10/12/2006
• Status: Active Grant

• Current Assignee: M.D. Stephen B. Murphy
• Original Assignee: M.D. Stephen B. Murphy
• Inventors: Murphy, Stephen B.
• Primary Examiner(s): Willse; David H
• Assistant Examiner(s): WOLF, MEGAN YARNALL
• Application Number:
  US11/546,664
• Publication Number:
  US 20080091274A1
• Time in Patent Office: 1,405 Days
• Field of Search: 623/22.11, 623 224- 2246, 623 2315- 2338, 623 2344- 2346, 623/19.14
• US Class Current: 623/22.42
• CPC Class Codes: A61F 2/32 for the hip
• CPC Class Codes: A61F 2/34 Acetabular cups
• CPC Class Codes: A61F 2/36 Femoral heads ; Femoral endoprostheses
• CPC Class Codes: A61F 2/3609 Femoral heads or necks; Connections of endoprosthetic heads or necks to endoprosthetic femoral shafts A61F2/3601 takes precedence
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2/367 Proximal or metaphyseal parts of shafts trochanteric devices connected to said proximal parts A61F2/30739
• CPC Class Codes: A61F 2002/30112 Rounded shapes, e.g. with rounded corners
• CPC Class Codes: A61F 2002/30158 trapezoidal
• CPC Class Codes: A61F 2002/30332 Conically- or frustoconically-shaped protrusion and recess
• CPC Class Codes: A61F 2002/30339 Double cones, i.e. connecting element having two conical connections, one at each of its opposite ends
• CPC Class Codes: A61F 2002/30355 Cylinder of elliptical or oval basis
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30538 for adjusting angular orientation
• CPC Class Codes: A61F 2002/3054 about a connection axis or implantation axis for selecting any one of a plurality of radial orientations between two modular parts, e.g. Morse taper connections, at discrete positions, angular positions or continuous positions
• CPC Class Codes: A61F 2002/3055 for adjusting length
• CPC Class Codes: A61F 2002/30604 modular
• CPC Class Codes: A61F 2002/30616 Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30706 specially designed for children, e.g. having means for adjusting to their growth
• CPC Class Codes: A61F 2002/3611 Heads or epiphyseal parts of femur
• CPC Class Codes: A61F 2002/3625 Necks
• CPC Class Codes: A61F 2002/365 : Connections of heads to necks
• CPC Class Codes: A61F 2002/3652 : Connections of necks to shafts
• CPC Class Codes: A61F 2002/4635 : using minimally invasive surgery
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 : made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2230/0004 : Rounded shapes, e.g. with rounded corners
• CPC Class Codes: A61F 2230/0026 : trapezoidal
• CPC Class Codes: A61F 2250/0006 : for adjusting angular orientation
• CPC Class Codes: A61F 2250/0082 : specially designed for children, e.g. having means for adjusting to their growth
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00179 : Ceramics or ceramic-like structures

Abstract

A modular hip prosthesis includes a femoral stem, a spherical head and a coupling member extending from the head defining a neck whose lower end forms a base which plugs into a socket at the top of the stem to form a tapered neck/stem junction. That junction is aligned with the stem axis and has a cross-section with opposite sides that extend generally parallel to the sides of the stem. With such an arrangement, that junction may be relatively long and have a relatively large cross-sectional area thus making a strong junction even in smaller femoral implants.

Claims

1. A hip prosthesis comprising

an elongated stem having a longitudinal stem axis and a metaphyseal flare leading up to a flat upper surface extending perpendicular to the stem axis and having opposite, relatively straight sides;

a tapered socket extending a selected distance into the stem from said upper surface, said socket having opposite sides extending substantially parallel to the opposite sides of said surface and being centered on the stem axis;

a substantially spherical head having a center of curvature, and

a coupling member releasably coupling the head to the stem, said coupling member including a neck having a lower end forming a base with a first axis that substantially coincides with the stem axis and an upper end with a second axis and connected to the head so that said second axis extends through said center of curvature and is angularly offset from the first axis, said base also having a length and taper such that it wedgingly engages in the socket to form a releasable, non-rotatable connection therewith which defines a tapered neck/stem junction centered on and aligned with said stem axis and which has a cross-section with opposite ends, one of which is wider than the other and that is elongated in the direction of the metaphyseal flare, said upper surface and cross-section each having the shape of a trapezoid with rounded corners so that the coupling member can only be coupled to the stem when the head is located above the metaphyseal flare.

2. The prosthesis defined in claim 1 wherein the connection between the upper end of the neck and the head is capable of being released.

3. The prosthesis defined in claim 2 wherein the connection between the upper end of the neck and the head comprises a Morse taper.

4. A hip prosthesis comprising an elongated stem having a stem axis and a planar upper surface, said upper surface having opposite, relatively straight sides and extending perpendicular to said axis, and

a tapered socket extending into the stem from said upper surface at said axis, said socket having an elongated mouth with opposite ends one of which is wider than the other and opposite relatively straight sides extending substantially parallel to the opposite sides of said upper surface, said upper surface and said socket mouth each having the shape of a trapezoid with rounded corners.

5. The prosthesis defined in claim 4 and further including a modular neck having a base with substantially the same size and taper as the socket wedgingly received in the socket.