Pyramid receptacle for coupling a prosthetic limb to a socket

A pyramid receptacle for coupling a prosthetic limb to a socket, comprising a unitary machined component formed with an externally-threaded neck section flanged by a larger-diameter disk. The disk is formed with a concave face, and a central cavity. A plurality of threaded set screws are journalled into the hollow threaded neck section through the threads thereof and into communication with the central cavity. Machining the threaded holes for the plurality of set screws directly through the hollow threaded neck section, and ensuring that the set screws stay flush or recessed when fully tightened effectively halves the length of the pyramid receptacle and facilitates angular adjustment of the prosthetic limb before affixing it in place, but does not significantly increase the profile length of the interconnection between socket and knee joint.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to prosthetics and, more particularly, to a prosthetic-limb coupling-socket adapter assembly that affords angular adjustment for the prosthetic limb, yet does not significantly increase the profile length of the interconnection between socket and knee or foot joint for amputation patients.

2. Description of the Background

There are a variety of different types of prosthetic devices for patients that have had either transfemoral (above-knee) or transtibial (below the knee) amputation. A typical transfemoral prosthetic device consists of a custom socket fitted over the residual limb, a structural component system affixed to the socket that may include a pylon and articulated replacement joints (such as a knee or ankle) depending on the patient and location of the amputation, and knee cuffs, belts or other systems to secure the device to the body. A prosthetic sock or liner is typically worn over the residual limb within the socket to cushion the area of contact, and, in some cases, realistic-looking skin is provided over the structural components for aesthetic reasons.

As shown inFIG. 1, the socket22receives the wearer's residual limb. The socket22is typically a fiberglass or other composite shell molded to conform to the user's residual limb. The socket22is seated on a choke adapter24. Choke adapter24includes an array of branches26that grip the socket22. Typically, the branches26are integrally and permanently molded inside the socket22. The permanently-attached choke adapter24positions a screw-tightenable C-ring clamping collar28directly beneath the socket22. In addition to being screw-tightenable in a clamping manner, collar28is internally threaded. A pyramid receptacle40includes an externally-threaded end that is screw-threaded into the collar28of choke adapter24. The other end of pyramid receptacle40screw-clamps to a pyramidal link-plate10mounted to the knee-joint assembly for transfemoral (above-knee) patients. Alternatively, the other end of pyramid receptacle40screw-clamps to a pyramidal coupling on a foot assembly for transtibial (below the knee) patients. A plurality of screws may be inserted through holes18in the pyramidal link-plate10to secure it to the respective prosthetic limb components fastened there beneath (an articulating knee joint and foot are shown). The conventional pyramidal link-plate10and the conventional pyramid receptacle40are primarily based upon the “Adjustable Link” described in U.S. Pat. No. 3,659,294 to Glabiszewski, the disclosure of which is incorporated herein by reference.

Specifically, and as shown inFIG. 1, the conventional pyramidal link-plate10wields a frustopyramidal, four-sided boss12projecting from a dome-shaped, or a spherically-convex-shaped base14, which in turn projects from a plate member16. The plate member16will typically include four screw- or bolt-receiving, through-holes18corresponding to a standard (within the industry) four-hole pattern. The pyramid receptacle40fits over the four-sided boss12, is angularly adjusted as desired, and then screw-clamps by set screws45onto the four-sided boss12to maintain the alignment. In fitting prosthetic limbs to patients, it is often necessary to modify and adjust the alignment and orientations of the various prosthetic limb components with respect to each other during the initial fitting or after the patient has worn the prosthetic limb for a period of time. The four-sided boss12engagement with the pyramid receptacle40allows the prosthetist to adjust the angular orientation before fixing it in place. However, the foregoing configuration requires several components and takes up considerable linear space. It is critically necessary to preserve the same pivoting axes on the prosthetic side, at the same height, as would have existed with the non-prosthetic limb. However, with certain transfemoral amputees, the allocable distance between the distal end of the patient's residual limb and the patient's natural knee center is very short, and it is difficult to size the foregoing plate member16, and pyramid receptacle40so that the combined length of the components between a prosthetic limb socket22and the prosthetic knee joint60is equal to the distance between the distal end of the patients residual limb and the patient's natural knee center. If the combined length of the coupling components is too long the knee center on the prosthetic side will be too low, thus causing gait deviation.

The same issues arise for transtibial (below the knee) patients because the very same length requirements apply beneath the distal end of the residual limb and the prosthetic foot.

Accordingly, there is a need for a prosthetic-limb coupling-socket adapter assembly suitable for both transfemoral (above the knee) patients as well as transtibial (below the knee) patients, that affords rotatable (angular) adjustment for the prosthetic limb or foot, yet does not significantly increase the profile or length of the attachment of the interconnection components.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a prosthetic-limb coupling-socket adapter assembly that substantially recesses the pyramid receptacle into the C-ring clamping collar of the choke adapter, so as not to significantly increase the profile length of the interconnection between socket and knee joint.

It is another object to provide a prosthetic-limb coupling-socket adapter assembly as above that facilitates angular adjustment of the prosthetic limb or foot before affixing it in place.

It is another object to provide a shock/torsion-control prosthetic-limb coupling-socket adapter with all the foregoing qualities.

The above and other objects, features and advantages of the present invention will become readily apparent from the following detailed description thereof which is to be read in connection with the accompanying drawings, in which an adapter is described for coupling a prosthetic limb or foot to a transtibial or transfemoral socket. The adapter is formed with a cylindrical neck capped by a disk-like flange. The neck is opened at both ends and defined by external screw-threads along its entire length for screw-insertion into an existing choke adapter, and a radial array of internally threaded screw-holes are journalled sidelong into the neck section through and interrupting the external screw-threads around said neck section. The disk section is integrally and coaxially joined on one side to the neck section, but has a larger diameter. The other (outward facing) side of the disk section is defined by a concave face formed with a central cavity therein, the cavity extending into and forming a chamber within the neck section for insertion of the pyramidal post of a conventional link-plate. A plurality of headless threaded set screws are inserted into the radial array of threaded screw-holes for locking engagement with the post of the conventional link-plate.

An alternate embodiment of the prosthetic-limb coupling-adapter assembly is provided which implements the concept with a shock/torsion adapter to enable limited transverse plane rotation and vertical shock absorption of the pyramidal post of the conventional link-plate, thereby reducing limb asymmetries and improving comfort leading to increased confidence and stability during gait.

The prosthetic-limb coupling-adapter assembly is suitable for both transfemoral (above the knee) patients as well as transtibial (below the knee) patients, and affords rotatable (angular) adjustment for the prosthetic limb or foot, yet minimizes the profile or length of the attachment of the interconnection components.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a pyramid receptacle for a prosthetic-limb (or foot) coupling assembly that still affords rotatable (angular) adjustment for the prosthetic limb, yet does not significantly increase the profile or length of the attachment of the interconnection components.

FIGS. 2-3are perspective views of the pyramid receptacle100according to an embodiment of the present invention. Pyramid receptacle100comprises a unitary precision-machined part formed with a hollow threaded neck section130flanged by a larger-diameter disk120. The hollow threaded neck section130is a open-ended cylindrical section having an external first diameter d1, length l1, and defined by external screw-threads along its entire length l1. Neck section130protrudes upward to a flat-topped circular face, and is peripherally sized to fit within the C-ring clamping collar28of choke adapter24(FIG. 1), and is screw-threaded and clamped therein.

In the preferred embodiment disk120is integrally formed with neck section130but extends outward there from, having a slightly larger diameter d2. However, one skilled in the art should understand that disk120is not an essential part of the invention and can be eliminated if desired. The bottom face of the disk120is formed with a concave surface109to forma bearing surface against the convex portion14of the conventional pyramidal link-plate10ofFIG. 1. At the center of the concave surface109a central aperture107is defined and opens outward, preferably in an eight-petal flower configuration as illustrated, to receive and seat the frustopyramidal four-sided boss12projecting from the pyramidal link-plate10(ofFIG. 1). A plurality of headless threaded set screws105are inserted into a radial array of threaded screw-holes106, the screw-holes being journalled into the sides of the hollow threaded neck section130and penetrating into the hollow cavity of central aperture107to bear against the frustopyramidal four-sided boss12, selectively affixing its position.

Preferably, four (4) threaded set screws105are journalled into four internally screw-threaded holes106extending through the hollow threaded neck section130and into communication with the hollow interior chamber therein. As best shown inFIGS. 2 and 3, the internally-screw-threaded bore holes106are precision-machined in a radial array directly through the threads of the neck section130, and are spaced from each other in a horizontal plane ninety degrees apart. It is important that the internally-screw-threaded bore holes106be precision-tapped through the threads of the neck section130so as not to introduce any discontinuities into the helical screw threads of the neck section130. This is essential to eliminate incongruities when screw-inserting the neck section130into the clamping collar28of choke adapter24as shown inFIG. 1. The axis of each bore hole106is preferably angled upward slightly (with regard toFIG. 2) from the horizontal plane at acute angles of about 2-10 degrees, so as to converge inward and upward at a camber. The length of the headless threaded set screws105is calculated so that they fully reside within the neck section130when abutting the boss12projecting from the pyramidal link-plate10(ofFIG. 1).

The shape and flowered petal-configuration of the central aperture107cooperates with the frustopyramidal shape of boss12to allow the prosthetist to adjust the angular orientation of the of the pyramid receptacle100before locking it in position with set screws105. So long as the set screws105remain flush or recessed below the threads of the threaded neck section130even when locked against the four-sided boss12, the hollow threaded neck section130of pyramid receptacle100can still be screwed into the C-ring clamping collar28of choke adapter24as shown inFIG. 1.

This careful machining of threaded radial holes106for the plurality of set screws105directly through the hollow threaded neck section130, and ensuring that the set screws105stay flush or recessed when fully tightened effectively halves the length of the pyramid receptacle100when compared to the prior art. This takes on special significance because it facilitates angular adjustment of the prosthetic limb before affixing it in place, yet minimizes the profile length of the interconnection between socket and knee joint. Once the pyramid receptacle100is attached on one side to the four-sided boss12at the proper camber, the entire lower leg assembly can be secured (clamped and/or threaded) in the clamping collar28to affix the pyramid receptacle100to the socket.

The above-described invention may be used for transtibial (below the knee) patients, where a similar pyramidal link-plate10attaches a prosthetic foot. All the same advantages accrue because the very same length requirements apply between the distal end of the residual limb and the prosthetic foot.

FIG. 4illustrates the pyramid receptacle100used for a transtibial (below the knee) patient in coupling to a foot assembly.

The concept of the present invention may also be implemented as a shock/torsion adapter. Integrating a shock/torsion adapter into the pyramid receptacle100enables limited transverse plane rotation and vertical shock absorption of the pyramidal link-plate10and can help reduce limb asymmetries and improve comfort leading to increased confidence and stability during gait.

FIG. 5is a perspective top view of an embodiment of a pyramid adapter200according to the present invention which incorporates an integral shock/torsion adapter for providing limited angular rotation against a predetermined resistance, and also vertical load absorption. The combination of rotation/resistance and vertical load absorption affords more natural movement when used by transtibial as well as transfemoral amputees reducing stress forces against the residual limb. The pyramid adapter200is exteriorly similar in form and function to that ofFIGS. 1-4, and includes an internal rotation spindle250to allow limited rotation and shock absorption from a home position against a controlled resistance that biases the rotation spindle250back to the home position. The pyramid adapter200also provides a vertical shock absorption characteristic by damping compression/vertical loading.

FIG. 6is a top view of the disassembled pyramid adapter200ofFIG. 5, andFIG. 7is a side view. The hollow threaded neck section130is formed as a hollow annular sleeve open at the lower end and partially capped by an annular flange133at the upper end, flange133being defined by a smaller diameter circular central aperture135. The hollow threaded neck section130is also formed with a pair of opposing inwardly-directed radial partitions137, e.g., solid walls running top to bottom and spanning the interior of the hollow threaded neck section130from the surface of its inner cylindrical wall to the central aperture135. As above the cylindrical exterior wall131is exteriorly threaded from top to bottom as perFIGS. 1-4. The threaded neck section130fits down overtop the rotation spindle250. The spindle250is formed as a hollow cylindrical stem253rising centrally from a larger-diameter flange252at the bottom. The spindle250is also formed with a pair of opposing outwardly-directed radial partitions257, e.g., solid walls running approximately two-thirds the height of spindle250from the bottom flange252toward the top. The hollow threaded neck section130fits overtop the stem253and rotates thereon, stem253protruding outward through circular top aperture135. The distal top end of stem253is formed with an annular slot257for accepting a C-ring259, C-ring259thereby retaining the hollow threaded neck section130on the stem253but free to rotate. With the hollow threaded neck section130mounted on the spindle250, the radial partitions257of spindle250span the interior to the inner walls of threaded neck section130, and the radial partitions137of the hollow threaded neck section130span to the stem253of spindle250. The two pairs of diametric partitions137,257effectively divide the interior space into quadrants and yet remain free to rotate relative to each other. The space between the partitions137,257define four radially-spaced pockets259for seating a corresponding plurality of semi-circular torsion and vertical shock limiters175. The torsion/shock limiters175are elastic (such as silicon rubber, urethane or other resilient material), and are sandwiched between the inner wall of neck section130and stem253, held captive between the partitions137,257for rotation and held captive between annular flange133, and bottom flange252allowing for vertical load absorption. In the preferred embodiment, four crescent-shaped torsion/shock limiters175are used, one in each pocket259in each quadrant. The elasticity of the torsion/shock limiters175is chosen to allow a predetermined limited degree of rotational freedom and load absorption of the hollow threaded neck section130relative to the stem253. Thus, when the threaded neck section130is rotated or compressed relative to the stem253, all four torsion/shock limiters175become compressed between partitions137and partitions257for rotation and flange133and252for load absorption. In addition, the thickness of the torsion/shock limiters175is chosen to impart predetermined bias between the hollow threaded neck section130relative to the bottom flange252. This way, the pyramid adapter200also provides a vertical shock absorption characteristic by damping compression/vertical loading.

This affords limited rotation and shock absorption of spindle250from a home position against a controlled elastic resistance, to a maximum angular rotation and load absorption, with a bias back to the home position.

The stem253is hollow and open downward to accept the pyramidal link-plate10ofFIG. 1inserted therein from beneath. The stem253is further defined by four radially-oriented threaded screw-bores106leading axially inward through the stem253into the hollow for securing the pyramidal link-plate10therein. Two of the threaded screw-bores106lead axially inward through the partitions257in spindle250, and two lead axially inward directly through the spindle250between the partitions257, the four threaded screw-bores106being angularly offset 90 degrees. All of the threaded screw-bores accept insertion of set screws105, two set screws being slightly longer than the other two to fully traverse the partitions257. As shown, when fully inserted the sets screws105remain recessed in the stem253.

The frustopyramidal four-sided boss12projecting from the pyramidal link-plate10ofFIG. 1is inserted from beneath into the hollow cavity261of the stem253and is secured thereto by the headless threaded set screws105. The hollow threaded neck section130is then inserted onto the stem253of the spindle250and is secured thereon by C-clip259. The entire pyramid adapter200may then be screwed into the C-ring clamping collar28of choke adapter24as shown inFIG. 1.

FIG. 8is a side view top cut-away view of the spindle250with cylindrical stem253and the frustopyramidal four-sided boss12projecting from the pyramidal link-plate10ofFIG. 1inserted therein and secured thereto by the headless threaded set screws105. Upon rotation, the torsion/shock limiters175are squeezed between partitions137and partitions257. Upon vertical load the torsion/shock limiter175are compressed between flanges133and flange252.

FIG. 9is a side cut-away view of the spindle250as inFIG. 8illustrating ingress of the headless screws105through tapped screw holes106. This configuration provides an integral shock/torsion adapter with limited angular rotation and shock absorption against a predetermined resistance, and still substantially recesses the pyramid receptacle200into the C-ring clamping collar of the choke adapter, so as not to significantly increase the profile length of the interconnection between socket and knee joint.

It should now be apparent that the above-described prosthetic-limb coupling-adapter is suitable for both transfemoral (above the knee) patients as well as transtibial (below the knee) patients, and in both cases affords rotatable (angular) adjustment for the prosthetic limb or foot, yet minimizes the profile or length of the attachment of the interconnection components.