PROSTHETIC DIGIT

A prosthetic digit can include a proximal segment connected to an intermediate segment about a first axis of rotation and a distal segment connected to the intermediate segment about a second axis of rotation. A linkage can be connected to the proximal segment about a third axis of rotation and can couple the proximal segment to the distal segment. The linkage can be configured such that a distal end of the distal segment to rotate toward the proximal segment about the second axis of rotation when the intermediate segment is rotated in a palmar direction about the first axis of rotation. A unidirectional lock can allow the intermediate segment to rotate about the first axis of rotation in a palmar direction but not in a dorsal direction. A release mechanism can release the unidirectional lock to allow the intermediate segment to rotate in the dorsal direction.

TECHNICAL FIELD

Aspects of the disclosure relates to prostheses to replace one or more digits of a human hand.

BACKGROUND

Partial hand loss is a common amputation often impacting a person's ability to perform many tasks, such as recreational or professional tasks or life functions, such as dressing, eating, or preparing food. Prosthetic intervention can be used to restore a forceful grasp capability of the hand, such as between the thumb and the fingers, such that objects can be grasped even in the case of a partial hand loss. However, because digits of the hand have such wide-ranging functions, some prosthetic interventions may not effectively restore the functionality lost.

Three broad categories of available prostheses include cosmetic, passive, and active prostheses. Cosmetic prostheses generally aim to resemble original anatomy, but often include minimal functionality apart from aesthetics. Passive prostheses include those that are not actively driven, but often include one or more movable joints, for example, mimicking joints of a digit. Such devices can be adjustable to several configurations to mimic postures of the replaced anatomy. Active prostheses are generally driven by the body or other power source (e.g., electrical power). However, active prostheses are often complex, expensive, and generally have low power output.

SUMMARY

In general, the present disclosure is directed to prosthetic digits for the human hand and associated systems and techniques involving a prosthetic digit. In some example, a prosthetic digit according to the disclosure incudes multiple segments joined together a respective rotational axis to replication different bone and joint segments of the native digit being replaced by the prosthetic component. For example, the prosthetic digit may include a proximal segment, a distal segment, and an intermediate segment positioned between the proximal and distal segments. The three segments can be rotationally coupled to each other around different axes of rotation. In some configurations, the proximal segment of the prosthetic digit may be configured to partially or fully replace a metacarpal bone of the hand while the intermediate and distal segments of the prosthetic digit may be configured to partially or fully replace phalange bones of the hand (e.g., a proximal phalanx, intermediate or middle phalanx, and/or distal phalanx).

A prosthetic digit according to the disclosure may include movable joints, mimicking joints of a native digit, along with spring extension and locking retraction functionality. In use, a wearer can articulate the distal segment of the prosthetic digit relative to the intermediate segment of the prosthetic digit and/or articulate the intermediate segment of the prosthetic digit relative to the proximal segment of the prosthetic digit. In some implementations, the prosthetic digit includes a linkage coupling the proximal segment to the distal segment such that, when the intermediate segment is articulated relative to the proximal segment, the distal segment articulates a corresponding amount relative to the intermediate segment via the linkage between the proximal and distal segments. In either case, the prosthetic digit may include a locking system to lock a relative amount of articulation between the different segments of the prosthetic digit, e.g., thereby setting the relative angles between the different segments of the digit to a positioned desired by the user based on the task being undertaken. The lock can be releasable by the user, with one or more springs in the prosthetic digit causing the different segments of the digit to articulate to their extended position upon release of the lock.

A prosthetic digit according to the disclosure may provide good functionality for a wearer without the cost and complexity of a more complex prosthetic digit. In some applications, a wearer may be fitted with a prosthetic digit according to the disclosure and the prosthetic digit may provide all the functionality required by the wearer to suitably restore their life functions. In some applications, a prosthetic digit according to the disclosure may provide an intermediate level of functionality less than that provided by a more complex active prosthetic digit. In practice, an amputee seeking a more complex active prosthetic digit may have to wait a significant amount of time before receiving a more complex active prosthetic digit. For example, the amputee may have to satisfy rigorous insurance requirement to demonstrate eligibility for the complex active prosthetic digit and, even then, wait for fabrication and fitting of their new digit. In these situations, a prosthetic digit according to the disclosure may be used to help restore life function during a period while the amputee is waiting for a more complex active prosthetic digit and then replaced with that digit once available.

Independent of the specific circumstances under which an amputee acquires a prosthetic digit according to the disclosure, the prosthetic digit can provide a variety of different functional features. In some examples, the digit includes a locking system that includes a unidirectional lock and a release mechanism. The locking system can be configured to allow an intermediate segment of the digit to rotate in a first direction (e.g., palmar direction) about a first axis of rotation but lock the intermediate segment from rotating in an opposed direction (e.g., a dorsal direction). In some examples, the locking system includes a pawl and ratchet surface. For example, the unidirectional lock may provide a ratchet surface positioned on the intermediate segment and a pawl configured to engage the ratchet surface and prevent rotation of the intermediate segment in the dorsal direction. A lever can be spring biased in favor of the pawl engaging the ratchet surface and can be maniuplable to overcome the spring bias and disengage the pawl from the ratchet surface. In user, the wearer can depress a first end of the lever, disengaging the pawl from the ratchet surface and allowing a biasing force (e.g., spring) to cause the intermediate segment to move from a locked articulated position to a fully extended position.

In some configurations, the prosthetic digit also includes an anchor. The anchor can be operatively connected to the proximal segment of the prosthetic digit. For example, the proximal segment may be configured to be removably coupled to the anchor in a plurality of rotational positions. For instance, a system including the digit may include a wearable support that can be configured to be fastened to one or both of a wearer's hand or writ. The wearable support can include the anchor affixed thereto to facilitate attachment of the prosthetic digit to the wearable support via the anchor.

DETAILED DESCRIPTION

The present disclosure is generally directed to a prosthetic finger (referred to as a prosthetic digit) configured to replace a finger or thumb in partial or full hand loss conditions. The prosthetic digit can be composed of multiple segments rotatably coupled together to define joints between the different segments. The prosthetic digit can include one more springs and/or locks to control and set the positioning of different segments of the prosthetic digit relative to each other. In use, the wearer may press a distal portion of the prosthetic digit one direction (e.g., a palmer direction) by pressing the distal portion of the digit against a stationary surface. This can cause the distal portion of the digit to rotate relative to a proximal portion of the digit, e.g., cause the distal portion to retract or curl. A locking system can hold the rotated position of the distal portion relative to the proximal portion. The wearer can release the lock, allowing one or more springs in the digit to push the retracted distal portion of the digit back to an extended (unretracted) position. The prosthetic digit can operate without electrical power and may be devoid of a battery, electrical wiring, and/or other electrical control features.

To further understand example prosthetic digits according to the disclosure, the anatomy of the hand will first be described with respect toFIG.1.FIG.1shows an illustration of the skeletal anatomy of a hand100. The hand100includes five digits110,120,130,140,150, with digit110corresponding to a thumb. Broken line160shows an approximate location of the palm of the hand, with digits110,120,130,140,150extending therefrom. Thumb110includes a metacarpophalangeal (MCP) joint112and an interphalangeal (IP) joint114. In the illustrated example, each of remaining digits120,130,140,150include an MCP joint102, a proximal interphalangeal (PIP) joint104, and a distal interphalangeal (DIP) joint106, as labeled inFIG.1on digit150.

During movement of one or more digits, a person can move a digit in a palmar direction, in which one or more joints bend and the digit moves closer to the palm, or can extend a digit in a dorsal direction, moving the digit away from the palm. Palmar motion of each of digits110,120,130,140,150can bring the digits inward to close a fist, bending MCP joints102, PIP joints104, and DIP joints106of digits120,130,140,150and MCP joint112and IP joint114of digit110. Opening the hand from a first includes moving each such joint in a dorsal direction.

Some prostheses described herein can be used to replace a digit lost at or proximal of the MCP joint102,112. Some such prostheses can provide palmar movement of the prosthesis and provide resistance against movement in the dorsal direction so as to enable grasping pressure using the prosthesis and remaining anatomy, such as between a thumb and the prosthesis. Similarly, in some examples, a prosthesis can take the place of the thumb and resist dorsal movement so as to enable grasping pressure between one or more of digits120,130,140,150and the prosthesis.

FIG.2Ashows an example prosthetic digit200. Prosthetic digit200includes a proximal segment202connected to an intermediate segment204about a first axis of rotation290. In some examples, the proximal segment202and intermediate segment204are coupled via a pin extending through each component along the first axis of rotation290to permit a rotational relationship between the components. The prosthetic digit200also includes a distal segment206connected to the intermediate segment204about a second axis of rotation292. In some examples, the intermediate segment204and distal segment206are coupled via a pin extending through each component along the second axis of rotation292to permit a rotational relationship between the components.

In some examples, proximal segment202, intermediate segment204, and distal segment206comprise a hard, lightweight material, such as a plastic or carbon fiber material. In some embodiments, each such segment is made from the same material. In some examples, each of the proximal segment202, intermediate segment204, and distal segment206include a carbon fiber material. In some embodiments, one or more of the proximal segment202, intermediate segment204, and the distal segment206can be manufactured by molding, 3D printing, and/or other manufacturing techniques.

In the illustrated example, intermediate segment204is shown as rotated downward relative to proximal segment202. Analogizing the direction of rotation to the hand and digit anatomy discussed with respect toFIG.1, the intermediate segment204can be said to be rotated about the first axis of rotation290in a palmar direction (shown by arrow230). Similarly, the distal segment206is shown as being rotated about the second axis of rotation292in a palmar direction. Extending the prosthetic digit200from the curled configuration shown inFIG.2Acan include rotating the intermediate segment204in a dorsal direction (shown by arrow232) about the first axis of rotation290and/or rotating the distal segment206in a dorsal direction about the second axis of rotation292as discussed elsewhere herein.

In some embodiments, prosthetic digit200can include a locking mechanism configured to limit rotation of one segment about an axis of rotation. In some examples, the locking mechanism comprises a unidirectional locking mechanism in which a segment is free to rotate in a first direction about an axis of rotation but rotation in the opposite direction about the same axis of rotation is inhibited by the locking mechanism. In some embodiments, the locking mechanism comprises a unidirectional locking mechanism freely permitting rotation of the intermediate segment204in a palmar direction about the first axis of rotation290while resisting rotation of the intermediate segment204in a dorsal direction about the first axis of rotation290.

In the example ofFIG.2A, prosthetic digit200includes a ratchet surface216on the intermediate segment204and a lever212attached to the proximal segment202. The lever includes a first end210and a second end214, wherein the second end is configured to act as a pawl relative to the ratchet surface216. The lever212and ratchet surface216can act in concert to form the locking mechanism wherein the pawl function of the second end214of the lever212engages one or more teeth on the ratchet surface216of the intermediate segment204and resists rotation of the intermediate segment204in the dorsal direction about the first axis of rotation290. However, the locking mechanism ofFIG.2Afreely permits rotation of the intermediate segment204in the palmar direction about the first axis of rotation290.

In some embodiments, lever212is configured to rotate about axis of rotation298in order to selectively engage or disengage pawl at the second end214of the lever212from the ratchet surface216. Lever212can be spring biased such that the pawl engages the ratchet surface216when no outside force is applied. However, depressing first end210of the lever212can overcome the spring bias and cause the lever to rotate about axis298and cause the pawl at the second end214of the lever212to disengage from the ratchet surface216. Thus, in some embodiments, depressing the first end210of the lever212disengages a unidirectional lock and permits free rotation of the intermediate segment204in both the palmar and dorsal directions about the first axis of rotation290.

In some examples, a prosthetic digit includes a linkage coupled to the proximal segment202and the distal segment206. An example linkage is discussed in greater detail with respect toFIGS.2C and2Das well asFIGS.3A-3C. The linkage can be configured to cause a distal end of the distal segment to rotate in a palmar direction about the second axis292when the intermediate segment204is rotated in a palmar direction about the first axis of rotation290. In some such examples, palmar rotation of the intermediate segment204about the first axis of rotation290forces the linkage to rotate in the palmar direction about third axis of rotation294. Combined palmar rotation of the intermediate segment204about first axis of rotation290and linkage about the third axis of rotation294can force relative movement between an attachment point between linkage and the distal segment206(along axis296) and an attachment point between the intermediate segment204and the distal segment206(along axis292). Such movement can cause the distal segment206to rotate in a palmar direction about the second axis of rotation292.

In some examples, the pawl and ratchet surface configuration of the lever212and intermediate segment204creates a plurality of discrete rotational positions for the intermediate segment204about the first axis of rotation290. In some examples, a linkage creates a1:1relationship between unique rotational positions of the intermediate segment204about the first axis of rotation290and corresponding unique rotational positions of the distal segment206about the second axis of rotation292. Thus, in some embodiments, the prosthetic digit200can be locked into a plurality of discrete configurations wherein each configuration corresponds to a unique rotational position of the intermediate segment204about the first axis of rotation290and of the distal segment206about the second axis of rotation292.

The prosthetic digit200ofFIG.2Ais shown with an anchor250. In some embodiments, the prosthetic digit200is removable from anchor250. In some examples, anchor250can be fixedly attached to a wearer or to a wearable support configured to be worn by the user. In some such embodiments, a prosthetic digit such as prosthetic digit200can be removably attached to the anchor250in order to attach the prosthetic digit to the wearer.

FIG.2Bshows an alternate view of the prosthetic digit200shown in and described with respect toFIG.2A. In some embodiments, the distal segment206includes a fingertip surface226on a palmar surface of the distal segment206. In some examples, the fingertip surface226can be made from a different material from the distal segment,206, such as a more compliant material, for example, a complaint rubber material. A compliant fingertip surface226can provide a firm and/or non-slip gripping surface for the prosthetic digit200to assist in grasping an object.

In some examples, the proximal segment202includes a base pad surface222positioned on the palmar side of the proximal segment202. In some embodiments, the base pad surface222comprises a more compliant material than the proximal segment. For example, in some embodiments, base pad surface222comprises a compliant rubber. A compliant base pad surface222can provide a firm and/or non-slip gripping surface for the prosthetic digit200to assist in grasping an object.

In some embodiments, prosthetic digit200is configured such that, as the prosthetic digit articulates in a palmar direction (e.g., intermediate segment204rotates in a palmar direction about the first axis of rotation290and the distal segment206rotates in a palmar direction about the second axis of rotation292) fingertip surface226generally moves toward base pad surface222, as shown inFIG.2B. In some examples, such movement creates a clamping action between the fingertip surface226and the base pad surface222. A locking mechanism resisting dorsal movement of the prosthetic digit can operate in conjunction with the fingertip surface226and the base pad surface222to create a clamp-like mechanism whereby the fingertip surface226and base pad surface222can clamp to and hold an object in the space therebetween. In some examples, one or both of the fingertip surface226and base pad surface222includes a curved surface. In other examples, one or both of the fingertip surface226and the base pad surface222are flat surfaces.

FIGS.2C and2Dshow side views of the prosthetic digit200wherein the intermediate segment204and the distal segment206are in different rotational positions. In the example ofFIG.2C, prosthetic digit is in a fully-extended state. Compared to the curled state shown inFIGS.2A and2B, the intermediate segment204has rotated in a dorsal direction about axis290and the distal segment206has rotated in a dorsal direction about axis292. In some embodiments, the fully-extended configuration of the prosthetic digit200shown inFIG.2Cis a default position assumed by the prosthetic digit200when a releasable unidirectional locking mechanism (e.g., lever212and ratchet surface216) is released. Such a default position may be achieved, for example, by spring biasing the intermediate segment204to rotate in a dorsal direction about axis290. In some examples, the spring bias is created by an extension spring internal to the prosthetic digit and providing a downward pull on a proximal portion of the intermediate segment204toward a portion of the proximal segment202.

As shown inFIG.2C, proximal segment202can be attached to an anchor250to facilitate attaching prosthetic digit200to a wearer. The proximal segment202can be attached to an intermediate segment204via a pin280defining an axis of rotation (e.g., first axis of rotation290inFIG.2A) such that the intermediate segment204can rotate about the pin280. Intermediate segment204can be attached to distal segment206via a pin282defining an axis of rotation (e.g., second axis of rotation292inFIG.2A) such that the distal segment206can rotate about the pin282.

As discussed above, in some examples, distal segment206includes a fingertip surface226positioned on a palmar surface of the distal segment206. Additionally or alternatively, in some examples, the distal segment206includes a fingernail portion236protruding from a dorsal surface of the distal segment206. The fingernail portion236can facilitate using the prosthetic digit200to pick up or grasp small or thin objects, for example, picking up coins or other relatively flat objects.

In some embodiments, prosthetic digit200includes a linkage240coupled to the proximal segment202and the distal segment206. In the illustrated example, linkage240is coupled to proximal segment202via pin284, which can define an axis of rotation (e.g., axis of rotation294shown inFIG.2A). Linkage240can be coupled to the distal segment206at a position not shown inFIG.2Csuch that, as the intermediate segment204is rotated in a palmar direction about a rotational axis (e.g., defined at pin280), linkage240rotates in a palmar direction about a different rotational axis (e.g., defined at pin284) and pushes on an attachment point of the distal segment206so as to cause the distal segment to rotate in a palmar direction about yet another rotation axis (e.g., defined at pin282).

As shown in the example ofFIG.2C, each of the proximal segment202, the intermediate segment204, and the distal segment206add a distal projection length away from the anchor250. In some embodiments, projecting an axis of rotation290away from the anchor250by proximal segment202offsets the axis of rotation of the intermediate segment204from the attachment point of the prosthetic digit200to the anchor. The prosthetic digit can be configured such that, as the prosthetic digit200rotates in a palmar direction, the intermediate segment204shifts forward relative to the proximal segment202while the proximal segment202remains attached to the anchor. In some examples, rotation of the intermediate segment204about the axis of rotation290causes the intermediate segment204to shift forward relative to the proximal segment202without the proximal segment202shifting.

FIG.2Dshows a prosthetic digit200in an intermediate state. In the example ofFIG.2D, the intermediate segment204of the prosthetic digit200is rotated about an axis defined by pin280in a palmar direction relative to the configuration shown inFIG.2C. Similarly, the distal segment206of the prosthetic digit200is rotated about an axis defined by pin282in a palmar direction relative to the configuration shown inFIG.2C.

In the illustration ofFIG.2D, linkage240has rotated in a palmar direction about an axis defined by pin284. In some examples, linkage240is coupled to the proximal segment202at pin284and is coupled to the distal segment206. The prosthetic digit200ofFIG.2Dcan be configured such that rotation of the linkage240about axis defined by pin284and rotation of the intermediate segment204about an axis defined by pin280can cause the distal segment206to rotate about an axis defined by pin282. This can be caused by the relationship between attachment and rotation points between (i) the linkage240and the proximal segment202(e.g., at pin284), (ii) the intermediate segment204and the proximal segment202(e.g., at pin280), (iii) the intermediate segment204and the distal segment206(e.g., at pin282), and the linkage240and the distal segment206(e.g., at a point intersecting axis296shown inFIG.2Aand not shown inFIG.2D).

In some examples, a prosthetic digit is positionable to a plurality of configurations between a fully-extended configuration (e.g., the configuration shown inFIG.2C) and a fully-closed configuration. In some cases, a fully-closed configuration corresponds to a configuration in which the intermediate segment204is maximally rotated in the palmar direction about rotational axis290. In some embodiments, the fully-closed configuration corresponds to a configuration in which the fingertip surface226engages the base pad surface222. In other embodiments, the fully-closed configuration does not include the fingertip surface226engaging the base pad surface222, but instead includes a gap between the fingertip surface226and the base pad surface222. For example, in some embodiments, the configuration shown inFIG.2A or2Bis a fully-closed configuration.

FIGS.3A-3Cshow cross-sectional views of the example prosthetic digit and anchor ofFIG.2.FIG.3Ashows an example attachment of a proximal segment302of a prosthetic digit to an anchor350. In the illustrated example, anchor350includes a plate352and a flange354protruding therefrom. Flange354includes a receptacle356.

In the example ofFIG.3A, the proximal segment of a proximal segment302of the prosthetic digit includes a receptacle360in proximal side of the proximal segment302sized to receive the flange354of the anchor350. The proximal segment302further includes a channel362extending through from a distal side of the proximal segment302to the receptacle360. As shown, a removable fastener364is positioned within the channel362. In the illustrated example, removable fastener364comprises a screw or bolt, however, in various embodiments other fasteners could be used, such as a bayonet mount fastener.

In some examples, fastener364comprises a threaded post configured to extend through channel362in the proximal segment302. In some such embodiments, receptacle356in the flange354of the anchor350comprises complementary threads such that the threaded post of fastener364can be securely fastened to receptacle356. In some embodiments, receptacle356is itself threaded. In other examples, receptacle356can house a nut or other threaded components therein that is configured to threadably engage a threaded post of the fastener. Thus, in some embodiments, a prosthetic digit can be attached to the anchor350by inserting the flange354of the anchor350into the receptacle360of the proximal segment302and securing the proximal segment302to the anchor350by threading a fastener364into receptacle356of the flange.

Additionally, as noted above, in some embodiments, the fastener364is removable from the receptacle356of the anchor350. In such cases, once a prosthetic digit is mounted to the anchor350, the prosthetic digit can be removed, for example, for repair or replacement or any other reason. Additionally or alternatively, if the prosthetic digit is misaligned, the prosthetic digit can be adjusted relative to the anchor350.

In some examples, the flange354of the anchor350and the receptacle360of the proximal segment302are complementary in shape. In some cases, each comprises a circular shape. In some embodiments, the receptacle360can receive the flange354in a plurality of rotational orientations. In some cases, the complementary shapes are non-circular, but rather have complementary edges, points, grooves, or some other shape to permit a discrete number of rotational orientations (e.g., complementary square flange354and receptacle360could allow for up to four discrete rotational orientations). In some embodiments, an inner surface of the receptacle360and an outer surface of flange354are serrated in order to permit a finite number of orientations. In other examples, a continuum of rotational orientations is possible (e.g., if the complementary shapes are circular and do not require one of a plurality of discrete orientations). In either case (discrete or continuous rotational positions), in some embodiments, rotational orientation may be limited by other design factors, for example, restricting rotation to a finite amount of rotation from a base orientation (e.g., ±5°, ±10°, ±15°, ±30°, ±45°).

In some examples, such attachment and detachment ability can be used to fit a prosthetic digit to a wearer. In an example process, a prosthetic digit can be attached to an anchor affixed to a wearer (e.g., via a wearable support to which the anchor is affixed). Attaching the prosthetic digit can include engaging a threaded fastener364to receptacle356of the flange354of the anchor350, but not securing the fastener364fully so as to permit movement of the prosthetic digit relative to the anchor350. The process can include rotating the prosthetic digit about an axis relative to the anchor, for example, until the prosthetic digit is arranged in a target rotational position. In some examples, a target rotational position includes an orientation permitting the prosthetic digit to properly engage with an existing digit, such as a thumb, or to cooperate with another prosthetic digit. In some examples, the target orientation is determined empirically by rotating the prosthetic digit until a suitable orientation is found. The process can further include, once the prosthetic digit is rotated to the target rotational position, securing the prosthetic digit to the anchor in the target rotational position. Securing the prosthetic digit to the anchor can include tightening the threaded fastener364to prevent movement of the prosthetic digit relative to the anchor.

FIG.3Bshows a cross section of a prosthetic digit attached to an anchor. In the example, prosthetic digit300comprises a proximal segment302removably attached to anchor350via fastener364. The proximal segment302is attached to intermediate segment304at a pin380defining an axis of rotation about which intermediate segment304can rotate relative to proximal segment302such as described elsewhere herein. Intermediate segment304is attached to distal segment306at a pin382defining an axis of rotation about which distal segment306can rotate relative to intermediate segment304such as described elsewhere herein.

The prosthetic digit300includes a unidirectional locking mechanism comprising a lever312acting as a pawl engaging a ratchet surface316of the intermediate segment304. The intermediate segment304is permitted to rotate freely in a palmar direction about an axis defined at pin380, but is prevented from rotating in the dorsal direction, opposite the palmar direction, when pawl engages ratchet surface316. In some embodiments, lever312is spring biased so that pawl engages the ratchet surface316unless the spring bias is overcome. In some embodiments, lever is manipulable to overcome the spring bias to disengage pawl from the rachet surface316. In some examples, lever can rotate about an axis defined at pin388such that if a side of the lever opposite the pawl is depressed, the pawl disengages from the ratchet surface316and the intermediate segment304can rotate freely in both the dorsal and palmar directions.

In the example ofFIG.3, a linkage340is coupled to the proximal segment302at pin384and to the distal segment306at pin386and is configured to rotate relative to such components about axes defined by such pins. The linkage340can be configured such that rotation of the intermediate segment304in the palmar direction about an axis defined by pin380causes rotation of the linkage340about an axis defined by pin384. Such rotation and the relative position of pins can cause the distal segment306to rotate about an axis defined by pin382in response to the rotation of intermediate segment304about the axis defined by pin380.

The example ofFIG.3Bshows a fingertip surface326positioned on a palmar surface of the distal segment306and a base pad surface322positioned on a palmar surface of proximal segment302. As described elsewhere herein, in some embodiments, fingertip surface326and base pad surface322can be made from a more compliant material compared to other portions of the proximal segment302and the distal segment306.

As described above, in some examples, each of proximal segment302, intermediate segment304, and distal segment306extend away from the anchor350when the prosthetic digit is in an extended configuration, such as shown inFIG.3B. In some embodiments, when the prosthetic digit is in an extended configuration, the proximal segment302extends an axis of rotation about pin380a first distance D1from the anchor350, and intermediate segment304extends an axis of rotation about pin382a distance D2from the axis about pin380. In the illustrated example, a distal end of the distal segment306is a distance D3from the axis of rotation about pin382. In some examples, D1, D2, and D3are approximately equal in length. In other examples, D2>D1>D3. In some embodiments, Each of D1, D2, and D3are between 0.25 inches and 1.5 inches.

FIG.3Cshows a cross-section of a prosthetic digit rotated in a palmar direction compared to the configuration inFIG.3B. In the illustrated examples, intermediate segment304is rotated in a palmar direction about an axis defined by pin380compared to the configuration inFIG.3B. Such rotation, along with rotation of linkage340, coupled to proximal segment302via pin384and to distal segment306via pin, about an axis defined by pin384, causes the distal segment306to rotate in a palmar direction about axis defined by pin382. In some examples, the axis of rotation defined by pin380is offset from a central longitudinal axis of the intermediate segment304. In some cases, rotation of the intermediate segment304about the axis defined by pin380causes a portion of the intermediate segment304to move distally. In some embodiments, such distal motion contributes to the causal relationship between rotation of the intermediate segment304about the axis defined by pin380and rotation of the distal segment306about the axis defined by pin382.

As described elsewhere herein, in some embodiments, the prosthetic digit is configured such that, as the prosthetic digit300rotates in a palmar direction, the intermediate segment304shifts forward relative to the proximal segment302while the proximal segment302remains attached to the anchor. In some examples, rotation of the intermediate segment304about the axis defined by pin380causes the intermediate segment304to shift forward relative to the proximal segment302without the proximal segment302shifting. In some embodiments, the offset of the axis of rotation defined by pin380relative to a central longitudinal axis of the intermediate segment304contributes to such a distal shift of the intermediate segment304without shifting the proximal segment302.

As shown, in the configuration ofFIG.3C, fingertip surface326is moved toward base pad surface322as the prosthetic digit articulates in a palmar direction. In some embodiments, fingertip surface326and base pad surface322form a clamping mechanism to assist in grasping an object with the prosthetic digit. As shown in the cross-sectional view ofFIG.3C, pawl of lever312engages ratchet surface316of intermediate segment304, preventing dorsal rotation of the intermediate segment304about the axis defined by pin380. In some embodiments, the linked relationship between intermediate segment304and distal segment306prevents dorsal rotation of the distal segment306about the axis defined by pin386if the intermediate segment304is prevented from dorsal rotation about the axis defined by pin380. Thus, in some embodiments, the locking mechanism, when engaged, prevents motion of the fingertip surface326away from the base pad surface322.

FIG.4shows an exploded view of a prosthetic digit according to some embodiments. The example ofFIG.4includes a prosthetic digit400having a proximal segment402couplable to anchor450. A threaded fastener464extends through a section of the proximal segment402and engages a threaded nut465, which is positioned in flange454of the anchor450. In some embodiments, securing the threaded fastener464to threaded nut465while flange454of the anchor engages a receptacle of the proximal segment402secures the proximal segment402to the anchor450.

The proximal segment402is configured to connect to intermediate segment404at a first axis of rotation, which can be located where hole470of the proximal segment402aligns with hole471of the intermediate segment404. As shown, hole471of the intermediate segment404is offset from a central longitudinal axis of the intermediate segment404, which can cause one or more components of the prosthetic digit400to move distally as the intermediate segment404rotates about the first axis of rotation.

The prosthetic digit400includes a distal segment406configured to connect to the intermediate segment404about a second axis of rotation, which can be located where hole472of distal segment406aligns with hole473of the intermediate segment404. A linkage440is configured to couple the proximal segment402to the distal segment406, and can be connected to the proximal segment at an axis of rotation, which can be located where hole474of the proximal segment402and hole439of linkage440align. Linkage can connect to distal segment406at a location where hole441of linkage and hole476of distal segment406align. In some embodiments, the linkage is configured to cause a distal end of the distal segment to rotate toward the proximal segment about the second axis of rotation when the intermediate segment is rotated in a palmar direction about the first axis of rotation.

The prosthetic digit400includes a lever412configured to act as a pawl and engage ratchet surface416of the intermediate segment404as described elsewhere herein to form a unidirectional lock. Lever can be connected to intermediate segment404at a location where hole479of the lever and hole478of the intermediate segment404align. Lever412can be spring biased into a locking position, in which pawl engages ratchet surface416, by a spring413, which can bias a proximal end of the lever412upward to hold the pawl against the ratchet surface416. The proximal end of the lever412can be depressed to rotate the lever412about the aligned holes478,479to disengage pawl from ratchet surface416and release the unidirectional lock.

As described herein, in some examples, the unidirectional lock formed by pawl and ratchet surface416resist dorsal rotation of intermediate segment404. In some embodiments, intermediate segment404is spring biased to rotate in the dorsal direction about an axis where holes470and471meet such that action of the unidirectional lock resists against the spring bias. Such spring bias can be created by spring405, which can include an extension spring that pulls a proximal end of the intermediate segment404toward a portion of the proximal segment402to cause dorsal rotation of the intermediate segment404.

The exploded view ofFIG.4further shows a fingertip surface426configured to attach to a palmar side of distal segment406and a base pad surface422configured to attach to a palmar side of the proximal segment402.

FIG.5shows a plurality of views of an anchor and a proximal segment of a prosthetic digit configured to attach to the anchor.FIG.5includes a top-down view, bottom-up view, a side view, a plurality of perspective views, and a cross-sectional view of an example embodiment.

FIG.6shows a plurality of views of an example prosthetic digit in an extended configuration and attached to an anchor.FIG.6shows a plurality of perspective views, a side view, a front-on view, and a cross-sectional view taken along line6-6of the front-on view.

FIG.7shows a plurality of views of an example prosthetic digit in a curled configuration and attached to an anchor.FIG.7shows a plurality of perspective views, a top-down view, a bottom-up view, a side view, a front-on view, and a cross-sectional view taken along line7-7of the front-on view.

FIG.8shows a wearable support configured to be attached to a wearer. In various examples, wearable support is configured to be securely fastened to one or both of a wearer's hand or wrist, such as via one or more straps or the like. In the illustrated example, wearable support800holds a plurality of anchors810,820,830,840, each configured to receive a prosthetic digit to affix to the wearable support via the anchor. In various embodiments, the wearable support can be sized to support any of one, two, three, four, or more anchors. For example, a custom wearable support can be created to provide an anchor at a location of a digit that has been amputated at or proximal to an MCP joint. In some examples, one or more such anchors are permanently affixed to the wearable support800, such as via lamination, an adhesive attachment, or other attachment processes. In some examples, an anchor is affixed to the wearable support via an anchor plate of the anchor, such as via anchor plate812of anchor810inFIG.8. In some embodiments, the anchor plate812can secure the anchor810to the wearable support800such that a prosthetic digit can be affixed to the anchor810via a flange814attached to the anchor plate812, such as described elsewhere herein.

FIG.9shows a wearable support attached to a wearer's anatomy and supporting a plurality of prosthetic digits. As shown, wearable support900is attached to a wearer's hand and wrist region. As shown, wearable support900supports prosthetic digits910,920,930, and940. As discussed elsewhere herein, in some examples, the wearable support900includes a plurality of anchors configured to support a corresponding plurality of prosthetic digits910,920,930, and940. In some embodiments, the rotational position of one or more prosthetic digits910,920,930, and940can be adjusted relative to the anchor to which it is mounted in order to adjust the alignment of the prosthetic digit to another object, such as a wearer's anatomy.

In the example ofFIG.9, prosthetic digits910,920,930, and940are supported by a wearable support900secured to a wearer's anatomy. As shown, prosthetic digits910,920,930, and940are in a curled position and assist the wearer in grasping object950. As described herein, in some embodiments, a prosthetic digit includes a unidirectional locking mechanism permitting rotation of one or more components in a palmar direction (in the illustrated example, to close/curl the prosthetic digit), and preventing rotation in the opposite, dorsal direction. In such case, a prosthetic digit such as shown inFIG.9can be used to securely grasp object950without opening due to the unidirectional lock resisting dorsal rotation of the prosthetic digit.

In some embodiments, to engage a prosthetic digit in the closed configuration, the prosthetic digit can be manually rotated in the palmar direction without obstruction by the unidirectional lock until the prosthetic digit reaches a desired position. Once at the desired position, the unidirectional lock prevents undesired dorsal rotation, permitting the prosthetic digit to assist in grasping and/or functions.

In some embodiments, prosthetic digits described herein can utilize one or more features described in U.S. Pat. No. 11,311,393 (“the '393 patent”), granted Apr. 26, 2022, and entitled UNIVERSAL DIGIT, the entire contents of which is incorporated herein by reference. For example, one or more segments can longitudinally rotatable relative to a segment attached thereto. In some examples, an intermediate segment can be attached to a proximal segment via configurations described in the '393 patent. Additionally or alternatively, a proximal segment can be attached to an anchor via configurations described in the '393 patent. Additionally or alternatively, a distal segment can be attached to an intermediate segment via configurations described in the '393 patent. For example, in some embodiments, one segment may be rotatably coupled to an adjacent segment wherein a button mechanism can enable repositioning of one segment relative to the adjacent segment when the button mechanism is depressed, and repositioning in such a manner is prevented after the button is released.

Various examples have been described. These and others are within the scope of the following claims.