Patent Description:
Often, when a patient is sedated for a surgery, the patient is supported by and secured to braces or supports coupled to a surgical table. Sometimes, unique supports are provided for a patient's extremities such as arm boards, leg supports, hand boards, stirrups, and boots.

Supports known in the art sometimes secure patients to resist patient movement. Such supports can sometimes allow excessive patient movement relative to the supports. The position and orientation of supports is often adjusted during surgery to improve access to a surgical site or to move portions of the patient's body such as bones, muscles, tendons, and ligaments to evaluate the surgical results.

<CIT>, in the name of Allen Medical Systems Inc. , describes a boot stirrup for use with a surgical table. The boot stirrup includes a support arm, a surgical boot, and a lockable joint coupled to the support arm and the surgical boot. The support arm is configured to couple to a surgical table for movement about a plurality of axes relative to the surgical table. The surgical boot is configured to support and/or immobilize the foot and leg of the patient. The lockable joint is configured to selectively permit movement of the surgical boot relative to the support arm. The support arm includes a longitudinal axis and a spar that is configured to support the lockable joint and the surgical boot to maintain the patient's foot and leg in a selected position. The lockable joint includes a release lever that is configured to be gripped by a user and is pivotable about a lever axis to move the lockable joint into a locked position and an unlocked position. In the unlocked position, the lockable joint permits movement of the surgical boot along the longitudinal axis relative to the support arm and rotation of the surgical boot about the longitudinal axis relative to the support arm. In the locked position, the lockable joint blocks movement of the surgical boot along the longitudinal axis relative to the support arm and rotation of the surgical boot about the longitudinal axis relative to the support arm. The lockable joint is further configured to allow limited movement of the surgical boot about a transverse axis and a medial-lateral adjustment axis when the lockable joint is in either one of the unlocked and the locked positions.

<CIT>, in the name of Allen Medical Systems, describes an adjustable limb support system for an operating room table to adjustably orient and position a stirrup or boot. The support system provides an adjustable support in combination with a vertically adjustable support. The adjustable support includes a retaining block, a compression block, and a compression head. The retaining block defines a passage for receiving a connecting rod secured to the stirrup or boot. The compression block defines a passage for receiving the support arm of the vertical adjustable support. The compression head when tightened prevents translation and rotation of the compression block on the support arm, and rotation of the compression block and the retaining block relative to each other. When the compression head is untightened the compression block can be translated or rotated on the support arm, and the blocks can be rotated relative to each other, in order to orient and position the stirrup or boot. The stirrup or boot freely rotates or swings about the axis of the connecting rod at all times.

The present application discloses one or more of the following features alone or in any combination. According to the present invention, a limb support comprises a support structure, a limb rest and a coupler. The support structure includes a spar configured to be supported from a patient support apparatus and adjustable relative to the patient support apparatus, the spar having a longitudinal axis. The limb rest is configured to support the limb of a patient supported on the patient support apparatus. The coupler is configured to support the limb rest relative to the support structure. The coupler includes a release that is biased to a locked position to prevent movement of the limb rest relative to the support structure, and that is selectively actuable to simultaneously (i) release the limb rest to rotate about a first axis, (ii) release the limb rest to rotate about a second axis orthogonal to the first axis to a plurality of orientations, and (iii) release the coupler for movement along the longitudinal axis of the spar.

In some embodiments, the release includes a biased locking assembly that urges a floating lock member to engage a wedge member into engagement with a fixed lock member to urge the release into a locked condition preventing movement of the limb rest about the first and second axes and preventing movement of the coupler relative to the support structure.

In some embodiments, the floating lock member engages two wedge members; the two wedge members each engaging the fixed lock member in the locked condition.

In some embodiments, the wedge members each engage a fixed plate such that the load of the bias member is transferred through the wedge members to the plates, the plates cooperating to induce a load in a shaft.

In some embodiments, the load on the shaft is transferred to a lock that engages the support structure to secure the coupler to the support structure.

In some embodiments, the release includes a cam that is rotated to cause the floating lock member to disengage the wedge member.

In some embodiments, a limb rest mounting plate is rotatable about a third axis, regardless of the position of the release.

In some embodiments, the release is manually actuable between a released position permitting movement about the first axis, about the second axis, and along the support structure, and a locked position preventing movement about the first axis, about the second axis, and along the support structure.

In some embodiments, the release is configured such that manual actuation achieves a mechanical advantage that overcomes the bias member.

In some embodiments, the coupler includes a guide channel configured to engage a guide member of the support structure to maintain an orientation of the coupler as it moves along the spar.

In some embodiments, the coupler includes a carriage that is configured to engage the support structure.

In some embodiments, the carriage configured to engage the guide member.

In some embodiments, the carriage includes a bias member that is configured to bias at least a portion of the carriage into engagement with the guide member.

In some embodiments, the carriage further includes at least one needle bearing configured to engage the guide member.

In some embodiments, the carriage includes at least one bearing member that is biased to engage the guide member.

In some embodiments, at least one wedge member includes a feature that limits the range of motion of the limb rest about the first axis.

In some embodiments, the floating lock member is a floating lock ring that includes a first annular surface that engages one or more wedge members, a fixed lock ring includes a second annular surface that engages one more wedge members, and wherein the one or more wedge members are free to move relative to the first and second annular surfaces when the release is in the released position.

In some embodiments, the coupler further comprises a floating lock member, a biased locking assembly, a fixed lock member, a wedge member, a fixed plate, and a shaft engaged with the fixed plate, wherein the floating lock member engages the wedge member to induce a load between the wedge member and the fixed plate such that the load of the biased locking assembly is transferred through the wedge member to the plate, the plate inducing a load in the shaft.

In some embodiments, the release is operable to disengage the floating lock member from the wedge member so as to reduce the load induced in the shaft.

In some embodiments, the load induced in the shaft is configured to lock the coupler to the support structure.

In some embodiments, a reduction in the load in the shaft is configured to release the coupler from the support structure such that the coupler is moveable relative to the support structure.

In some embodiments, the coupler further comprises a floating lock member, a biased locking assembly, a fixed lock member, a plurality of wedge members, a plurality of fixed plates, and a shaft engaged with at least one fixed plate, wherein the floating lock member engages the wedge members and the wedge members engage the fixed lock member such that the wedge members induce a load between the wedge members and the fixed plates such that the load of the biased locking assembly is transferred through the wedge members to the plates, the plates inducing a load in the shaft.

In some embodiments, the reduction in the load in the shaft is configured to release the coupler from the support structure such that the coupler is moveable relative to the support structure.

In some embodiments, the wedge members are coupled together by a bias structure that urges the wedge members to engage the floating lock member and fixed lock member.

In some embodiments, the bias structure coupling the wedge members is insufficient to cause the wedge members to prevent movement of the limb rest support plate relative to the support structure.

In some embodiments, the coupler includes a carriage that is configured to be on the support structure, the carriage including a frame and a lock moveable relative to the frame, the lock being biased relative to the frame to the secure the carriage to the support structure when the load is induced in the shaft.

In some embodiments, the carriage further includes a bias member that is configured to resist the load of the shaft.

In some embodiments, the load of the shaft overcomes the bias of the bias member of the carriage when the load is induced in the shaft.

In some embodiments, the bias of the bias member is sufficient to release the lock of the carriage when the load in the shaft is removed.

In some embodiments, the limb rest support plate is rotatable about a third axis, regardless of the position of the release.

In some embodiments, the release is manually actuable between a released position permitting movement of the limb rest support plate about the first axis, about the second axis, and along the support structure, and a locked position preventing movement of the limb rest support plate about the first axis, about the second axis, and along the support structure.

It is also envisaged that the limb support comprises a spar, a limb rest, and a coupler. The spar is configured to be supported from a patient support apparatus and adjustable relative to the patient support apparatus, the spar having a longitudinal axis. The coupler is interposed between the limb rest and the spar, the coupler includes a release that is selectively actuable to (i) release the limb rest to rotate about a first axis that is offset from the longitudinal axis of the spar to a plurality of orientations relative to the spar, and (ii) release the coupler relative to the spar to allow the coupler to move along the longitudinal axis of the spar.

In some embodiments, the coupler includes a release mechanism that is acted upon by the release to permit rotation of the limb rest about the first axis. In some embodiments, the release mechanism includes an actuator that moves along the first axis when the release is actuated. In some embodiments, the release moves in a direction that is perpendicular to the first axis. In some embodiments, the release mechanism includes a locking plate that is disengaged by the actuator. In some embodiments, the release mechanism includes guides to maintain an orientation of the locking plate. In some embodiments, the guides are positioned on a base member that is secured to the spar. In some embodiments, the guides preclude rotation of the locking plate when the release is actuated and when the release is not actuated. In some embodiments, the locking plate includes anti-rotation features that engage to prevent rotation of the limb rest when the release is not actuated. In some embodiments, the anti-rotation features are disengaged to thereby allow rotation of the limb rest when the release is actuated.

In some embodiments, actuation of the release causes movement of a linkage that causes the coupler to be released from the spar to allow movement of the coupler along the spar. In some embodiments, the linkage transfers motion from a first plunger to cause longitudinal movement of a release member in a direction perpendicular to the movement of the first plunger. In some embodiments, the linkage further comprises an actuator that is pivotable about a second axis that is perpendicular to the first axis. In some embodiments, the linkage comprises a cam that is pivotable about the second axis. In some embodiments, the actuator is secured to the cam. In some embodiments, the cam comprises an axle that has an axis that is collinear with the second axis. In some embodiments, the cam comprises an eccentric that is secured to the axle and rotates therewith. In some embodiments, the eccentric includes a lobe that is offset from the second axis. In some embodiments, the linkage comprises a second plunger that moves between a first position when the release is not actuated and a second position when the release is actuated. In some embodiments, the lobe engages the second plunger. In some embodiments, rotation of the cam about the second axis causes the lobe to move the plunger to release the coupler from the spar.

In some embodiments, the coupler includes a clamp that is selectively actuated to engage the spar to prevent movement of the coupler along the spar. In some embodiments, the clamp is released when the release is actuated. In some embodiments, the second plunger moves to cause the clamp to release the spar.

In some embodiments, the coupler further comprises a rotation lock that prevents rotation of the limb rest about the longitudinal axis of the spar.

In some embodiments, the coupler further comprises a collar that supports the clamp.

In some embodiments, the rotation lock prevents movement of the clamp relative to the collar.

In some embodiments, the rotation lock is releasable to permit rotation of the clamp relative to the collar.

In some embodiments, the rotation lock is adjustable to allow the clamp to be adjusted to a plurality of positions relative to the collar.

In some embodiments, the spar and the collar include a plurality of interengageable anti-rotation elements that cooperate to prevent rotation of the collar about the axis of the spar.

In some embodiments, the coupler includes a selectively engageable brake to prevent movement of the coupler along the longitudinal length of the spar. In some embodiments, when the rotation lock is disengaged, the brake may be disengaged to permit movement of the coupler along the longitudinal length of the spar. In some embodiments, the brake comprises an elastomeric pad.

It is also envisaged that a limb support may comprise a support structure, a limb rest, and a coupler. The support structure is configured to be mounted to a patient support apparatus and includes a spar having a longitudinal axis and a guide tube having a longitudinal axis that is parallel to the longitudinal axis of the spar. The limb rest is configured to support the limb of a patient supported on the patient support apparatus. The coupler is supported from the spar and supports the limb rest. The coupler has a single release that is manually actuable to permit a user to move the release between a locked position and a released position, wherein when the release is in the released position the limb rest is simultaneously adjustable relative to the spar with at least two degrees of freedom.

In some embodiments, when the release is in the released position, the limb rest is simultaneously adjustable relative to the spar with at least four degrees of freedom.

In some embodiments, when the release is in the released position, the limb rest is simultaneously adjustable relative to the spar in at least three degrees of freedom.

In some embodiments, the release is only operable to lock three of the four degrees of freedom.

The coupler comprises a floating lock member, a biased locking assembly, a fixed lock member, a plurality of wedge members, a plurality of fixed plates, and a shaft engaged with at least one fixed plate. The floating lock member engages the wedge members and the wedge members engage the fixed lock member such that the wedge members induce a load between the wedge members and the fixed plates such that the load of the biased locking assembly is transferred through the wedge members to the plates, the plates thereby inducing a load in the shaft.

In some embodiments, the release is operable to disengage the floating lock member from the wedge members so as to reduce the load induced in the shaft.

In some embodiments, the load induced in the shaft is operable to lock the coupler to the spar.

In some embodiments, the reduction in the load in the shaft releases the coupler from the spar such that the coupler is moveable along the longitudinal axis of the spar.

In some embodiments, the bias structure coupling the wedge members is insufficient to prevent movement of the limb rest relative to the spar.

In some embodiments, the coupler includes a carriage that is supported on the spar, the carriage including a frame and a lock moveable relative to the frame, the lock being pivoted relative to the frame to secure the carriage to the spar when the load is induced in the shaft.

In some embodiments, the carriage further includes a bias member that is configured to resist the load induced in the shaft. In some embodiments, the load induced in the shaft overcomes the bias of the bias member of the carriage when the load is induced in the shaft by the biased locking assembly. In some embodiments, the bias of the bias member is sufficient to release the lock of the carriage when the load in the shaft is removed.

In some embodiments, the release includes a cam that is rotated to cause the floating lock member to disengage the wedge members.

In some embodiments, the limb rest is rotatable about a third axis, regardless of the position of the release.

In some embodiments, the release is manually actuable between a released position permitting movement of the limb rest about the first axis, about the second axis, and along the spar, and a locked position preventing movement of the limb rest about the first axis, about the second axis, and along the spar.

In some embodiments, the release is configured such that manual actuation achieves a mechanical advantage that overcomes the bias of the biased locking assembly.

In some embodiments, rotation of the coupler about the longitudinal axis of the spar is precluded by a guide member. In some embodiments, the coupler includes a carriage that engages the spar. In some embodiments, the carriage also engages the guide member. In some embodiments, the carriage includes a bias member that biases at least a portion of the carriage into engagement with the guide member. In some embodiments, the carriage further includes at least one needle bearing that engages the guide member. In some embodiments, the carriage includes at least one bearing member that is biased to engage the guide member.

In some embodiments, the spar further includes a release trigger operable to release the spar for adjustment of the spar relative to a patient support apparatus.

It is also envisaged that the limb support comprises a spar configured to be supported from a patient support apparatus and adjustable relative to the patient support. The spar has a longitudinal axis. The limb support also comprises a limb rest and a coupler interposed between the limb rest and the spar. The coupler includes a release that is selectively actuable to (i) release the limb rest to rotate about a first axis that is offset from and parallel to the longitudinal axis of the spar to a plurality of orientations relative to the spar, (ii) release the limb rest to rotate about a second axis orthogonal to the first axis to a plurality of orientations, and (ii) release the coupler relative to the spar to allow the coupler to move along the longitudinal axis of the spar.

The release is biased to a locked position to prevent movement of the limb rest relative to the spar.

In some embodiments, the release includes a biased locking assembly that urges a floating lock member to engage a wedge member into engagement with a fixed lock member to urge the release into a locked condition preventing movement of the limb rest about the first and second axis and preventing movement of the coupler along the longitudinal axis of the spar.

In some embodiments, the load on the shaft is transferred to a lock that engages the spar to secure the coupler to the spar.

In some embodiments, the release is manually actuable between a released position permitting movement about the first axis, about the second axis, and along the spar, and a locked position preventing movement about the first axis, about the second axis, and along the spar.

In some embodiments, rotation of the coupler about the longitudinal axis of the spar is precluded by a guide member. In some embodiments, the coupler includes a carriage that engages the spar. In some embodiments, the limb support further comprises an elongate guide member that is parallel to the spar and the carriage further engages the guide member. In some embodiments, the carriage includes a bias member that biases at least a portion of the carriage into engagement with the guide member. In some embodiments, the carriage further includes at least one needle bearing that engages the guide member. In some embodiments, the carriage includes at least one bearing member that is biased to engage the guide member.

In some embodiments, the floating lock member is a floating lock ring that includes a first annular surface that engages one or more wedge members, the fixed lock ring includes a second annular surface that engages one more wedge members, and wherein the one or more wedge members are free to move relative to the first and second annular surfaces when the release is in the released position.

In some embodiments, the release is operable to disengage the floating lock member from the wedge member so as to reduce the load induced in the shaft. In some embodiments, the load induced in the shaft is operable to lock the coupler to the spar. In some embodiments, the reduction in the load in the shaft causes the coupler to release the coupler from the spar such that the coupler is moveable relative to the spar.

In some embodiments, the release is operable to disengage the floating lock members from the wedge member so as to reduce the load induced in the shaft. In some embodiments, the load induced in the shaft is operable to lock the coupler to the spar. In some embodiments, the reduction in the load in the shaft causes the coupler to release the coupler from the spar such that the coupler is moveable relative to the spar.

In some embodiments, the wedge members are coupled together by a bias structure that urges the wedge members to engage the floating lock member and fixed lock member. In some embodiments, the bias structure coupling the wedge members is insufficient to cause the wedge members to prevent movement of the limb rest relative to the spar.

In some embodiments, the coupler includes a carriage that is supported on the spar, the carriage including a frame and a lock moveable relative to the frame, the lock being biased relative to the frame to secure the carriage to the spar when the load is induced in the shaft.

In some embodiments, the carriage further includes a bias member that is configured to resist the load of the shaft. In some embodiments, the load of the shaft overcomes the bias of the bias member of the carriage when the load is induced in the shaft. In some embodiments, the bias of the bias member is sufficient to release the lock of the carriage when the load in the shaft is removed.

Embodiments of limb supports with couplers will now be further described by way of example with reference to the accompanying drawings, in which:.

A limb support configured as a leg support <NUM> mountable to a patient support apparatus (not shown) and for positioning the leg of a patient in a number of different positions is shown in <FIG>. The leg support <NUM> includes a mount <NUM> for mounting the leg support <NUM> to a patient support apparatus as is known in the art. The mount <NUM> supports a lockable multi-axis coupler <NUM> that supports a spar <NUM> illustratively embodied as a rod and permits movement of the spar <NUM> relative to the mount <NUM> in a plurality of directions. An illustrative coupler suitable for use as coupler <NUM> is disclosed in <CIT>, titled "LEG HOLDER SYSTEM FOR SIMULTANEOUS POSITIONING IN THE ABDUCTION AND LITHOTOMY DIMENSIONS".

The spar <NUM> is supported relative to the mount <NUM> by a counterbalancing gas spring <NUM> which assists in supporting the weight of a patient's leg when the leg support <NUM> is in use or the position is being adjusted. A handle <NUM> positioned on a distal end of the spar <NUM> relative to the mount <NUM> is configured to be used by a user to position the spar <NUM> and includes a release trigger <NUM> that, when gripped by a user, causes the a lockable multi-axis coupler <NUM> to be released to allow the spar <NUM> to move relative to the mount <NUM>. Movement of the spar <NUM> relative to the mount <NUM> is facilitated in the pitch axis <NUM>, roll axis <NUM>, and yaw axis <NUM> as suggested in <FIG>. In the illustrative embodiment, this permits abduction, adduction, and lithotomy adjustments of the patient's leg. In should be understood that the movement could be equally applicable to a patient's arm.

The illustrative leg support <NUM> is configured to support a patient's left leg. In many cases, a second leg support that is a mirror duplicate of the leg support <NUM> will be used to support the right leg of a patient. The present disclosure includes an adjustable coupler <NUM> that permits of adjustment of the relative position and orientation of a limb rest <NUM> relative to the spar <NUM>. As will be explained in further detail below, the adjustable coupler <NUM> permits discrete adjustment of the position of the limb rest <NUM> about the spar <NUM> that provides additional roll axis adjustment of the limb rest <NUM>. Still further, the limb rest <NUM> may be rotated about an axis <NUM> shown in <FIG> to change the orientation of the limb rest <NUM> relative to the spar <NUM>.

Referring to <FIG>, the adjustable coupler <NUM> includes a release <NUM> that includes a handle <NUM> that may be pulled in the direction of arrow <NUM> to move the release <NUM> in the direction of arrow <NUM> shown in <FIG>. As will be described in further detail below, the movement of release <NUM> in the direction of arrow <NUM> is transferred by a cam action to a plunger <NUM> to move the plunger <NUM> between a first position shown in <FIG> and a second position shown in <FIG>. The movement of plunger <NUM> causes a locking mechanism <NUM> of the adjustable coupler <NUM> to be released to permit movement of a portion of the coupler <NUM> relative to a limb rest support plate <NUM> about the axis <NUM> to change the orientation of the limb rest <NUM> relative to the spar <NUM>.

In addition, the downward movement of the plunger <NUM> is transferred to an actuator <NUM> which acts on a plunger <NUM> to move the plunger <NUM> between the first position shown in <FIG> and a second position shown in <FIG>. In the second position, the plunger <NUM> separates a first leg <NUM> and a second leg <NUM> of a clamp <NUM> to release the clamp <NUM> relative to the spar <NUM> and thereby allow the coupler <NUM> to move along the length of the spar <NUM> to change the distance between the coupler <NUM> and the mount <NUM>. A bias member <NUM> urges the locking mechanism <NUM> to re-engage and allows the actuator <NUM> to return to the first position shown in <FIG> and <FIG> so that the limb rest <NUM> is fixed relative to the spar <NUM>. In addition to the bias of bias member <NUM>, which is illustratively embodied as a coil spring, the plunger <NUM> is urged to the first position by a bias assembly <NUM>, illustratively embodied as a embodied as a group of Belleville washers, and by the bias the clamp <NUM>, which will be discussed in further detail below.

Referring again to <FIG>, the clamp <NUM> is supported in a collar <NUM> which includes a number of grooves <NUM> (best seen in <FIG>) which engage longitudinal ribs <NUM> formed about the outer surface of the spar <NUM>. The interaction of the grooves <NUM> and ribs <NUM> preclude rotation of the collar <NUM> about the spar <NUM>. The clamp <NUM> is fixed to the collar <NUM> by a spring-biased lock arm <NUM> which locks the clamp <NUM> relative to the collar <NUM> to prevent rotation of the clamp <NUM> about the spar <NUM>. However, as will be discussed in further detail below, the lock arm <NUM> permits the clamp <NUM> to be positioned in multiple different orientations relative to the collar <NUM> by releasing the lock arm <NUM>, moving the clamp <NUM> about the spar <NUM>, and re-engaging the lock arm <NUM> with the clamp <NUM> to secure the clamp <NUM> in the new orientation.

To explain in further detail, the coupler <NUM>, shown in an exploded view in <FIG>, includes the release <NUM> which engages the plunger <NUM> through a pin <NUM> that is fixed to the plunger <NUM> and received in an inclined guide <NUM> formed in a body <NUM> of the release <NUM>. The body <NUM> is positioned in a channel <NUM> formed in plunger <NUM> and is moveable relative to the plunger <NUM>. Movement of the release <NUM> in the direction of arrow <NUM> causes the pin <NUM> to be acted upon by the inclined guide <NUM>, which through a cam action urges the pin <NUM> downwardly in the direction of an arrow <NUM> which is parallel to axis <NUM>. The release body <NUM> is supported in a channel <NUM> of the limb rest support plate <NUM> and trapped between the limb rest support plate <NUM> and the limb rest <NUM> so that the force applied to the release <NUM> is applied to the plunger <NUM> as all other movement is restrained by the assembly of the release <NUM> to the limb rest support plate <NUM>.

A lock plate <NUM> is supported on a spring <NUM> which is trapped between lock plate <NUM> and a base <NUM> of the coupler <NUM>. The spring <NUM> biases the lock plate <NUM> upwardly and, through the lock plate <NUM> biases the plunger <NUM> in the direction opposite the arrow <NUM>. This bias urges the release <NUM> to the first position shown in <FIG>. The lock plate <NUM> includes a number of teeth <NUM> formed about an outer edge <NUM>. The teeth <NUM> are configured to mate with grooves <NUM> formed in the limb rest support plate <NUM> when the lock plate <NUM> is in the first position. When the bias of the spring <NUM> is overcome and the lock plate <NUM> dis-engages the limb rest support plate <NUM>, the limb rest support plate <NUM> is free to rotate about the axis <NUM>. This movement is permitted as the base <NUM> is fixed to the clamp <NUM> through an arm <NUM> and the lock plate <NUM> is fixed against rotation relative to the base <NUM> by a number of legs <NUM> which have channels <NUM> that receive protrusions <NUM> formed in the base <NUM>. The legs <NUM> of the lock plate <NUM> are free to move relative to the protrusions in the direction of arrow <NUM>. However, when the lock plate <NUM> is engaged with the teeth <NUM> of the limb rest support plate <NUM>, the limb rest support plate <NUM> is precluded from rotation about the axis <NUM> through the engagement of the lock plate <NUM> with the base <NUM> and the connection between the base <NUM> and the arm <NUM> that is fixed to the base <NUM> and the clamp <NUM>.

Referring to <FIG>, it should be noted that the illustrative limb rest support plate <NUM> comprises two identical half-rings <NUM> that are engaged together to form the limb rest support plate <NUM>. As illustrated in <FIG>, the half-rings <NUM> are formed such that when the half-rings <NUM> are assembled, the limb rest support plate <NUM> is formed to include a flange <NUM> which underlies a groove <NUM> on the lower annular edge of the limb rest support plate <NUM>. The base <NUM> is formed to include flange <NUM> which overlies a groove <NUM> which, when the half-rings <NUM> are assembled over the base <NUM>, engage the respective groove <NUM> and flange <NUM> of the limb rest support plate <NUM>. When coupler <NUM> is secured to the limb rest <NUM>, the base <NUM> and the limb rest support plate <NUM> are secured together so that there is no movement of the base <NUM> relative to the limb rest support plate <NUM>. The lock plate <NUM> is constrained to move between the first positon of <FIG> and the second position of <FIG> as the plunger <NUM> moves. A lower surface <NUM> of the plunger <NUM> engages an upper surface <NUM> of the lock plate <NUM> but is movable about the axis <NUM> when the release <NUM> is moved in the direction of arrow <NUM> to the second position of <FIG>.

While the movement of the lock plate <NUM> permits the adjustment of the limb rest support plate <NUM> about axis <NUM>, a separate linkage <NUM> transfers the movement of the plunger <NUM> in the direction of axis <NUM> to movement of the plunger <NUM> along an axis <NUM> which is perpendicular to axis <NUM>. The linkage <NUM> includes the actuator <NUM> and a cam <NUM> which is supported on trunnions <NUM> and <NUM> formed in the base <NUM>. The actuator <NUM> is a u-shaped member with two legs <NUM> and <NUM> that are secured to the cam <NUM> by pins <NUM>, <NUM>. The cam <NUM> includes an axle <NUM> and an eccentric <NUM> secured to the axle <NUM>. Rotation of the cam <NUM> about an axis <NUM> of the axle <NUM> causes the eccentric <NUM> to rotate as suggested in <FIG> so that the eccentric acts on a head <NUM> of the plunger <NUM> to urge the plunger <NUM> along axis <NUM> as suggested by the arrows <NUM> shown in <FIG>.

The plunger <NUM> includes a shaft <NUM> that has a cross-hole <NUM> through which a pin <NUM> (shown in <FIG>) inserted. The pin <NUM> is also received in the leg <NUM> of clamp <NUM> so that movement of the shaft <NUM> acts on leg <NUM> to urge leg <NUM> away from leg <NUM> of the clamp <NUM>. The clamp <NUM> is resiliently flexible and has a latent bias that is created by the web <NUM> of the clamp <NUM>. The arm <NUM> is secured to the leg <NUM> of the clamp <NUM>. The arm <NUM> is also secured to the base <NUM> by having a head <NUM> retain the bias assembly <NUM> inside a wall <NUM> of the base <NUM>. The arm <NUM> is further restrained by two pins <NUM>, <NUM> which are inserted into grooves <NUM>, <NUM> formed in the arm <NUM>. The pins <NUM>, <NUM> are positioned in the grooves <NUM>, <NUM> and received in two holes <NUM>, <NUM> formed in the base <NUM> to fix the arm <NUM> to the base <NUM>. A machine screw <NUM> is positioned in the leg <NUM> of the clamp <NUM> and received in a groove <NUM> of arm <NUM> to prevent the arm <NUM> from moving relative to the leg <NUM>. A second machine screw <NUM> is positioned in a first side <NUM> of leg <NUM> and threaded into a second side <NUM> of leg <NUM> to add additional clamping force to the arm <NUM>.

The plunger <NUM> being pinned to the leg <NUM> and free to move within an relative to the arm <NUM>, effects movement of leg <NUM> relative to leg <NUM> to overcome the bias of the web <NUM>. Thus, as the eccentric <NUM> rotates, a lobe <NUM> of the eccentric <NUM> engages the head <NUM> of plunger <NUM> to move the plunger <NUM> along axis <NUM> and cause the clamp <NUM> to release. The eccentric <NUM> is rotated by the action of a bottom surface <NUM> of the lock plate <NUM> on the actuator <NUM> to thereby cause the linkage <NUM> to pivot about the axis <NUM> as the plunger <NUM> is urged downwardly. Rotation of the eccentric <NUM> about the axis <NUM> in the direction of arrow <NUM> shown in <FIG> causes the lobe <NUM> to engage the head <NUM> and urge the plunger <NUM> along axis <NUM> to release the clamp <NUM>. The bias of the web <NUM> and the bias assembly <NUM> urge the plunger <NUM> in the direction opposite the arrow <NUM>. Thus, as the release <NUM> is released by a user, the lock plate <NUM> is urged to engage the limb rest support plate <NUM> and permits movement of the linkage <NUM> such that the cam <NUM> and actuator <NUM> pivot about axis <NUM> to return to the position shown in <FIG>.

It should be noted that the action of releasing both the locking mechanism <NUM> and the linkage <NUM> result from the cooperation of the actuator <NUM> and the lock plate <NUM>. However, in other embodiments, the clamp release could be omitted by omitting the linkage <NUM> and having only a rotation release as described relative to locking mechanism <NUM>. Similarly, locking mechanism <NUM> could be omitted and the plunger <NUM> could act directly on the actuator <NUM> such that an embodiment of the coupler <NUM> could include only the linkage <NUM> that releases the clamp <NUM>.

Heretofore, the clamp <NUM> has been described as having a constant relationship relative to the collar <NUM>. In the illustrative embodiment, the orientation of the clamp <NUM> about the axis <NUM> of the spar <NUM> is adjustable to a number of locations by releasing a clamp lock <NUM> and rotating the clamp <NUM> about the axis <NUM> of spar <NUM> as indicated by arrow <NUM> in <FIG>. The clamp lock <NUM> includes the lock arm <NUM> which is pivotable relative to the collar <NUM> and a series of grooves <NUM>, <NUM>, and <NUM> formed on the clamp <NUM>. When the clamp <NUM> is released by the release <NUM> and the clamp lock <NUM> is released, the clamp <NUM>, and the remainder of coupler <NUM>, is movable relative to the collar <NUM>. The lock arm <NUM> is formed to include a pair of receivers <NUM>, <NUM> on opposite ends. The receivers <NUM> each receive a leg <NUM> of a respective bias member <NUM>, illustratively embodied as a spring. The each spring <NUM> has another leg <NUM> that is received in one of two receivers <NUM>, <NUM> formed in the collar <NUM>. The lock arm <NUM> is positioned on a pin <NUM> which is received in a hole <NUM> formed in the collar <NUM> and which defines a pivot axis <NUM> about which the lock arm <NUM> pivots. The bias member <NUM> urges a flange <NUM> of the lock arm <NUM> into engagement with one of the grooves <NUM>, <NUM>, and <NUM> formed on the clamp <NUM> which thereby locks the clamp <NUM> relative to the collar <NUM>. To release the clamp <NUM> a user applies sufficient pressure to a handle <NUM> of the lock arm <NUM> to overcome the bias of the bias member <NUM> and thereby disengage the flange <NUM> from the respective groove <NUM>, <NUM>, and <NUM>.

In another embodiment shown in <FIG>, a leg support <NUM> includes a limb rest <NUM> supported by a coupler <NUM> relative to a spar <NUM>. As will the locking of the limb rest relative to a rotation axis <NUM> is accomplished with an action that is separate from the locking of the coupler <NUM> relative to the spar <NUM>. The coupler <NUM> includes a collar <NUM> that engages the spar <NUM>. The spar <NUM> is formed with two channels <NUM> and <NUM> formed along the longitudinal length of the spar <NUM>. The upper channel <NUM> acts to prevent rotation of the collar <NUM> relative to the spar <NUM> as will be discussed in further detail below.

As shown in <FIG>, the coupler <NUM> includes a clamp <NUM> that is supported from the collar <NUM> by an arm <NUM>. The arm <NUM> is fixed to both the collar and the clamp <NUM>. The clamp <NUM> includes a housing <NUM>, a limb rest support plate <NUM>, and a handle <NUM>. Referring now to <FIG>, the limb rest support plate <NUM> is supported on the housing <NUM> by a bearing <NUM>. The clamp <NUM> also includes a threaded member <NUM> that passes through the limb rest support plate <NUM>, bearing <NUM>, and housing <NUM> and has threads <NUM> that engage threaded hole <NUM> in the handle <NUM>. In addition, a bias member embodied as a group of Belleville washers <NUM> is positioned under a head <NUM> of the threaded member <NUM>. When the handle <NUM> is turned in a left hand direction as indicated by arrow <NUM>, the threaded member <NUM> moves in the direction of arrow <NUM>, which reduces the load applied to the bias member <NUM> is reduced. By reducing the load and, thereby, the bias, a clamping action that is effected by the clamp <NUM> is reduced such that the limb rest support plate <NUM> is movable relative to the housing <NUM> to rotate the limb rest <NUM> about the axis <NUM> to change the orientation of the limb rest <NUM> relative to the spar <NUM>. When the clamp <NUM> is tightened by reversing the direction of rotation of the handle <NUM>, the action of the bias member <NUM> and the threaded member <NUM> increase the clamping force of the clamp <NUM> so that rotation of the limb rest support plate <NUM> relative to the housing <NUM> is precluded.

Referring now to <FIG>, the collar <NUM> includes a housing <NUM> which is supported on two bearings <NUM>, <NUM> which engage the spar <NUM>. The bearings <NUM>, <NUM> are retained within the housing by abutting respective flanges (not shown) formed in the housing and respective snap-rings <NUM>, <NUM>. Referring to <FIG>, the housing <NUM> supports a spring-loaded handle <NUM> that pivots relative to the housing <NUM> on a pin (not shown) about an axis <NUM> and is urged in the direction of arrow <NUM> by a bias member <NUM> illustratively embodied as a helical spring. A block <NUM> is supported on an arm <NUM> of the spring-loaded handle <NUM> and is positioned to engage the channel <NUM> on the spar <NUM> when the handle <NUM> is in the position shown in <FIG>. When a grip <NUM> of the handle <NUM> is grasped by a user, the bias of bias member <NUM> may be overcome to move the block <NUM> out of channel <NUM>. In this way, movement of the collar <NUM> about the spar <NUM> in the direction of arrow <NUM> is permitted.

The collar <NUM> further includes an elastomeric pad <NUM> supported in the housing <NUM>. The pad <NUM> is deformable under a load to cause frictional interference between the collar <NUM> and the spar <NUM> to prevent movement of the collar <NUM> and, thereby, the coupler <NUM> along the spar <NUM>. The weight of the limb rest <NUM> and, when a patient is present, the weight of a patient's limb, are supported in cantilever from the collar <NUM> creating a moment that is supported by the pad <NUM>. The pad <NUM> deforms under the load causing friction between the pad <NUM> and a surface of the channel <NUM> which causes resistance against movement of the coupler <NUM> along the spar <NUM>.

To move the collar <NUM> and, thereby, coupler <NUM> along the spar <NUM>, a user squeezes the grip <NUM> of the handle <NUM> to disengage the block <NUM> from the channel <NUM>. The user then manually lifts the limb rest <NUM> to unload the pad <NUM>. Once the pad <NUM> is unloaded, the frictional resistance of movement along the spar <NUM> is removed and the coupler <NUM> is moveable to a new position on the spar <NUM>. Once the coupler <NUM> is positioned appropriately, the user lowers the limb rest <NUM> to re-load the pad <NUM> and releases the grip <NUM> to cause the anti-rotation block <NUM> to re-engage channel <NUM>.

Another embodiment of a limb support configured as a leg support <NUM> mountable to a patient support apparatus (not shown) and for positioning the leg of a patient in a number of different positions is shown in <FIG>. The leg support <NUM> includes the mount <NUM> and coupler <NUM> for mounting the leg support <NUM> to a patient support apparatus similar to the operation of leg support <NUM> discussed above. The leg support <NUM> includes a spar <NUM> that is supported by the coupler <NUM>. An adjustable coupler <NUM> supports a limb rest <NUM> from the spar <NUM> and is releasable to allow the position of the limb rest <NUM> to be adjusted along the length of the spar <NUM>. The adjustable coupler <NUM> includes a handle <NUM> which may be actuated to cause the coupler <NUM> to be released to allow adjustment of the limb rest <NUM> about an axis <NUM> and an axis <NUM>. When the handle <NUM> is actuated to a released position, the coupler <NUM> and limb rest <NUM> are free to move along the spar <NUM>, and the limb rest <NUM> is adjustable about the axes <NUM> and <NUM>. The handle <NUM> is biased to a locked position (shown in <FIG> and <FIG>) wherein the movement along the spar <NUM> and about axes <NUM> and <NUM> is precluded. As will be discussed in further detail below, the limb rest <NUM> is always free to rotate about an axis <NUM> through a limited range of motion. This allows the limb rest <NUM> to self-adjust to an appropriate position when the spar <NUM> is moved about the axes <NUM>, <NUM>, and <NUM> to adjust the positon of the patient's limb relative to the patient support apparatus that the mount <NUM> engages.

The illustrative leg support <NUM> is configured to support a patient's left leg. In many cases, a second leg support that is a mirror duplicate of the leg support <NUM> will be used to support the right leg of a patient. The present disclosure includes an adjustable coupler <NUM> that permits of adjustment of the relative position and orientation of a limb rest <NUM> relative to the spar <NUM>.

Referring to <FIG>, the adjustable coupler <NUM> includes a release <NUM> that includes the handle <NUM> that may be pulled in the direction of arrow <NUM> to move the release <NUM> in the direction of arrow <NUM> shown in <FIG>. As will be described in further detail below, the movement of handle <NUM> in the direction of arrow <NUM> is transferred by a cam action to a plunger <NUM> to move the plunger <NUM> between a first position shown in <FIG> and a second position shown in <FIG>. The handle <NUM> is pivotable relative to a base member <NUM> with two lever arms <NUM>, <NUM> coupled to a grip <NUM> providing a mechanical advantage to overcome a spring bias to release three degrees of freedom for the coupler <NUM> relative to the spar <NUM>. A second grip <NUM> is mounted on the side of the base member <NUM> so that a user may positon their palm on the grip <NUM> and grasp the grip <NUM> with their fingers to provide leverage for moving the handle <NUM> to a released position. In some cases, the user may grip a foot portion <NUM> of the limb rest <NUM> with their other hand to position the limb rest <NUM> when the release <NUM> is moved to the released position.

A general understanding of the operation of the coupler <NUM> may be best understood by reference to <FIG> which is a cross-sectional view of the coupler <NUM>. The handle <NUM> is shown in a neutral position but is movable relative to a base <NUM> about an axis <NUM> in the direction of arrow <NUM>. A cam <NUM> is driven by the handle <NUM> such that a shaft <NUM> rotates and drives a cam lobe <NUM> into contact with a member <NUM>. The member <NUM> engages a dependent shaft <NUM> such that the shaft <NUM> secures a biased locking assembly <NUM> which is illustratively embodied as a stack of Belleville washers <NUM> between a flange <NUM> of the shaft <NUM> and a flange <NUM> of a floating lock member, which is a floating lock ring <NUM>. The shaft <NUM> is secured to a fixed lock member in the form of a fixed lock ring <NUM> by a press fit. In some embodiments, the shaft <NUM> may be threaded into the fixed lock ring <NUM> or secured relative to the fixed lock ring <NUM> by other means. The movement of the handle <NUM> effectively causes the floating lock ring <NUM> to be urged downwardly in the direction of an arrow <NUM>. When the floating lock ring <NUM> is in the position shown in <FIG>, an annular cam surface <NUM> acts on a pair of wedge members in the form of wedge plates <NUM>, <NUM> urging the wedge plates <NUM>, <NUM> to engage with an annular surface <NUM> of the fixed lock ring <NUM>. The fixed lock ring <NUM> includes an upper plate <NUM> that functions as a limb rest mounting plate with the limb rest <NUM> being mountable to the upper plate <NUM> to move therewith.

Referring now to <FIG>, the base <NUM> is secured to the floating lock ring <NUM> by a number of press fit pins <NUM> that are pressed into holes <NUM> of the floating lock ring <NUM> and into holes <NUM> of the base <NUM>. The wedge plates <NUM> and <NUM> are also coupled together by a biased locking assembly <NUM>, which is embodied as four helical springs <NUM> in the disclosed embodiment.

Referring to <FIG>, as the wedge plates for <NUM>, <NUM> engage the annular surfaces <NUM>, <NUM>, the wedge plates <NUM>, <NUM> are also urged outwardly away from the axis <NUM> and into engagement with a pair of fixed plates <NUM>, <NUM>, respectively. Once the wedge plates <NUM>, <NUM> are fully engaged with the fixed plates <NUM>, <NUM>, the load of the biased locking assembly <NUM> is sufficient to resist movement of the fixed lock ring about the axis <NUM> and the axis <NUM>. As suggested in <FIG>, a pair of covers <NUM>, <NUM> are each secured to the wedge plate <NUM> by a pair of fasteners <NUM>. Thus, the release <NUM>, when it is in the locked position of <FIG>, prevents movement of the limb rest <NUM> relative to two degrees of freedom, namely, axes <NUM>, <NUM>. When the release <NUM> is moved to the released position shown in <FIG>, the limb rest mounting plate <NUM> and the limb rest <NUM> are free to move in two degrees of freedom about the axes <NUM>, <NUM>.

The release <NUM> also affects a third degree of freedom in that the release controls the locking of the coupler <NUM> to the spar <NUM>. A carriage <NUM> of the coupler <NUM> is supported on the spar <NUM> then moves relative to the spar <NUM> and a guide rod <NUM> to vary the distance between the limb rest <NUM> and the mount <NUM> which results in the variation of the distance of the limb support relative to a patient support apparatus to which the leg support <NUM> is mounted in use. The guide rod <NUM> and spar <NUM> are each coupled to a fixed coupler <NUM> positioned at one end of the guide rod <NUM>. The fixed coupler <NUM> is also engaged by a rod end <NUM> of the gas spring <NUM>. The spar <NUM> and guide rod <NUM> are coupled at an end of the guide rod <NUM> opposite the fixed coupler <NUM> by a mount <NUM>. The mount <NUM> secures the handle <NUM>, the guide rod <NUM>, and the spar <NUM>. The release trigger <NUM> extends through the spar <NUM> as shown in <FIG>.

Referring to <FIG>, the carriage <NUM> includes a frame <NUM> and a lock <NUM> which is pivotably supported on the frame <NUM> and pivotable about an axis <NUM> which is defined by a pin <NUM>. A bias member <NUM> engages the lock <NUM> and a tube shaft <NUM> which is secured to the frame <NUM> by a pair of pins <NUM>, <NUM> (best seen in <FIG>) and engages with the fixed plate <NUM>. When the release <NUM> is in the position shown in <FIG>, the floating lock ring <NUM> urges the wedge plates <NUM>, <NUM> outwardly away from the axis <NUM> to engage with the fixed plates <NUM>, <NUM>. Force is transferred through wedge plates <NUM>, <NUM> to the fixed plates <NUM>, <NUM>, urging them outwardly away from the axes <NUM>, <NUM>.

A shaft <NUM> extends through the fixed lock ring <NUM>, the fixed plates <NUM>, <NUM>, the wedge plates <NUM>, <NUM>, the tubular shaft <NUM>, engaging a pair of bearings <NUM>, <NUM> positioned in the tubular shaft <NUM> and shaft <NUM> and is secured to the lock <NUM> by a pin <NUM>. The shaft <NUM> is secured on the opposite end by a thrust bearing <NUM> and a lock nut <NUM> which is adjusted to provide a preload on the lock <NUM> that is sufficient to secure the carriage <NUM> to the spar <NUM> when the release <NUM> is in the position shown in <FIG>. The lock nut <NUM> is secured by a pin <NUM>. In other words, the action of the wedges <NUM>, <NUM> on the fixed plates <NUM>, <NUM> induces a load in the shaft <NUM> which is applied to the lock <NUM>. The load in the shaft <NUM> is transferred to the thrust bearing <NUM> and a thrust bearing <NUM> that is positioned between the tubular shaft <NUM> and the fixed plate <NUM>. The thrust bearings <NUM>, <NUM> permit rotation of a portion of the coupler <NUM> relative to the tubular shaft <NUM>, shaft <NUM>, and carriage <NUM> about the axis <NUM> at all times. When the release <NUM> is in a locked position, such as that shown in <FIG> and <FIG>, the load of the shaft <NUM> tends to resist rotation of that portion of coupler <NUM> about axis <NUM>, but an operator may use manual force to cause the rotation to adjust the pitch of the limb rest <NUM> relative to the spar <NUM>. In this way, the limb rest <NUM> is adjustable relative to the spar <NUM> in at least one degree of freedom at all times.

The bias member <NUM>, illustratively embodied as a helical spring, resists the load induced in the shaft <NUM>. However, in normal operating conditions the load induced in the shaft <NUM> is a multiple of the load of the bias member <NUM> such that the bias member <NUM> is overcome by the load of the shaft <NUM> and compresses. When the handle <NUM> is moved to a released position, such as that shown in <FIG>, then the shaft <NUM> is unloaded and the bias member <NUM> urges the lock <NUM> out of engagement with the spar <NUM> so that the carriage <NUM> is free to move along the spar <NUM>. Movement of the carriage <NUM> along the spar <NUM> is eased by the engagement of two bearings <NUM>, <NUM>, that support the frame <NUM> on the spar <NUM>. The bearings <NUM> and <NUM> are retained relative to the frame <NUM> by respective snap rings <NUM>, <NUM> as shown in <FIG> and <FIG>.

The frame <NUM> of carriage <NUM> does not directly engage the guide tube <NUM>, but the carriage <NUM> engages with the guide tube <NUM> through a pair of needle bearings <NUM>, <NUM>. The needle bearing <NUM> is secured to the frame <NUM> by a fastener <NUM> such that the needle bearing <NUM> is fixed relative to the frame <NUM>. The needle bearing <NUM> to is secured to a floating arm <NUM> which is pivotably connected to the frame <NUM> and pivotable about an axis <NUM>. A bias member <NUM>, illustratively embodied as a helical spring, engages the floating arm <NUM> urging the floating arm <NUM> to pivot about the axis <NUM> to engage the needle bearing <NUM> with the guide shaft <NUM>. A load is induced in the bias member <NUM> by a set screw <NUM> which is threaded into the frame <NUM> to create a preload in the bias member <NUM> sufficient to keep the needle bearing <NUM> to engaged with the guide shaft <NUM>. This arrangement eliminates the need for close tolerance machining and establishes an appropriate load in the needle bearings <NUM>, <NUM>. The engagement of the needle bearings <NUM>, <NUM> with the guide tube <NUM> resists the rotation of the coupler <NUM> about the spar <NUM> when a load is placed on the limb rest <NUM>.

Unlike the embodiment of limb support <NUM>, leg support <NUM> is not adjustable about the spar <NUM>, but role about the axis <NUM> is facilitated by clearance in the wedge plates <NUM>, <NUM> which each have a respective slot <NUM>, <NUM> which permit a limited amount of role about the axis <NUM> when the release <NUM> is moved to the released position, such as that shown in <FIG>. The range of motion in the roll direction is defined by the clearance between an outer surface <NUM> of shaft <NUM> and an outboard edge <NUM>, <NUM> of the respective slots <NUM>, <NUM>. Thus, the fixed lock ring <NUM> is permitted to rotate through an angle about axis <NUM>. That is limited by the slots <NUM>, <NUM>. In the illustrative embodiment, the angle of permitted rotation is about <NUM> degrees.

The coupler <NUM> includes a bearing structure <NUM> that is positioned in the fixed lock ring <NUM>. The bearing structure <NUM> includes an outer bearing housing <NUM> that is positioned through an aperture <NUM> in the fixed lock ring <NUM> best seen in <FIG>. Referring to <FIG>, a spherical bearing <NUM> is positioned in the outer bearing housing <NUM> and fully engages the shaft <NUM>. The spherical bearing <NUM> is secured to the outer bearing housing by a snap ring <NUM> and the outer bearing housing <NUM> is secured into the fixed lock ring <NUM> by a snap ring <NUM>. As the fixed lock ring <NUM> is pivoted about the axis <NUM>, the spherical bearing <NUM> permits some freedom of movement relative to the shaft <NUM>.

Claim 1:
A limb support (<NUM>) comprising
a support structure including a spar (<NUM>) configured to be supported from a patient support apparatus and adjustable relative to the patient support apparatus, the spar (<NUM>) having a longitudinal axis,
a limb rest (<NUM>) configured to support the limb of a patient supported on the patient support apparatus, and
a coupler (<NUM>) interposed between the limb rest (<NUM>) and the spar (<NUM>), the coupler (<NUM>) being configured to support the limb rest (<NUM>) relative to the support structure, the coupler (<NUM>) including a release (<NUM>) that is biased to a locked position to prevent movement of the limb rest (<NUM>) relative to the support structure, and that is selectively actuable to simultaneously (i) release the limb rest (<NUM>) to rotate about a first axis, (ii) release the limb rest (<NUM>) to rotate about a second axis orthogonal to the first axis to a plurality of orientations, and (iii) release the coupler (<NUM>) for movement along the longitudinal axis of the spar, wherein the coupler (<NUM>) further comprises a floating lock member (<NUM>), a biased locking assembly (<NUM>), a fixed lock member (<NUM>), a wedge member (<NUM>, <NUM>), a fixed plate (<NUM>, <NUM>), and a shaft (<NUM>) engaged with the fixed plate, wherein the floating lock member engages the wedge member to induce a load between the wedge member and the fixed plate such that the load of the biased locking assembly is transferred through the wedge member to the fixed plate, the fixed plate inducing a load in the shaft.