Abstract:
An ankle joint prosthesis comprised of a central core element capable of attachment to an artificial leg, coupled to two side elements capable for attachment to an artificial foot. The medial and lateral side elements envelop the central core lower region along a common central axis, and are coupled together by means of mechanical fastening and can be rotated relative to the central core and positively constrained to align in various orientations dependent of a specific grooved profile within each side element pair. The ankle joint orientation is affected by engaging an anterior and/or posterior located mechanical linkage enacting an upward linear movement on the guide pin plunger, thus allowing the side elements to rotate by means of a torque load until reaching an orientation held in place along a grooved profile. The load bearing elements shall be precision machined from Grade 5 Titanium.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX 
       [0003]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0004]    The invention generally relates to an ankle joint prosthesis that can be positioned for walking, and effectively transitioned to multiple orientations as for use while engaging adaptive sports activities, and in regards to this invention; aquatic and equestrian activity. 
         [0005]    The following patents may be relevant to the present invention: 
       U.S. PATENT DOCUMENTS 
       [0000]    
       
         U.S. Pat. No. 911,243 February 1909 Johannesen 
         U.S. Pat. No. 2,749,557 June 1956 Riddle 
         U.S. Pat. No. 3,419,227 December 1968 Werkmeister et al. 
         U.S. Pat. No. 3,480,972 December 1969 Prahl 
         U.S. Pat. No. 4,413,360 November 1983 Lamb et al. 
         U.S. Pat. No. 4,865,611 September 1989 Al-Turaiki 
         U.S. Pat. No. 5,156,630 October 1992 Rappoport et al. 
       
     
       FOREIGN PATENT DOCUMENTS 
       [0000]    
       
         0262319 January 1970 Russian Federation 
         2110806 October 1971 Federal Republic of Germany 
         0381347 May 1973 Russian Federation 
         1509641 May 1978 United Kingdom 
         0016268 October 1980 European Patent Office 
       
     
         [0018]    The most relevant patent to the present invention may be U.S. Pat. No. 5,156,630; Inventors: A. Rappoport, S. Shawe, and M. Ross; Issue Date 20 Oct. 1992. U.S. Pat. No. 5,156,630 to Rappoport, Shawe, &amp; Ross is directed to an ankle joint prosthesis comprised of an upper part for attachment to an artificial leg and a lower part for attachment to an artificial foot, with the upper and lower parts rotatively coupled and capable of being fixed in a first position for walking, a second fixed position for swimming, or a free-flexing mode for rowing, and skiing. 
         [0019]    Changing positions is effected by manually rotating a D-ring on the medial side of the ankle prosthesis by hand. 
         [0020]    Materials of construction of the ankle body is precision machined from lightweight/high strength plastic. 
         [0021]    Although the ankle joint prosthesis discussed above can be adjusted manually, it suffers some notable deficiencies, specifically; method of manipulation, limited fixed positions, and strength of materials utilized. 
         [0022]    Manually rotating the ankle by hand requires the prosthesis wearer to be stationary by means of standing on one leg or sitting to be able to fix the ankle into and out of the locked positions; this is not a desirable transition mode if you desire to be dynamic into and out of the water, either at a beach, pool or climbing a boat ladder. 
         [0023]    The fixed and locked positions are set for walking, and at approximately 75 degrees plantar flexion orientation for swim position only. The free-flex mode is used when the ankle joint is required to rotation freely, i.e. no resistance or ability to fix position. 
         [0024]    The ankle embodiment is made from lightweight/high strength plastic, but may not be durable during high energy activity. 
       BRIEF SUMMARY OF THE INVENTION 
       [0025]    A determined focus was concentrated on the deficiencies of the previously known ankle joint prosthesis. The applicant has invented an ankle joint prosthesis comprised of a central core element capable of attachment to an artificial leg, coupled with two side elements capable for attachment to an artificial foot. The medial and lateral side elements envelop the central core lower region along a common central axis, and are coupled together by means of mechanical fastening and can be rotated relative to the central core and positively constrained to align in various orientations dependent of a specific grooved profile within each side element pair. The ankle joint orientation is affected by engaging an anterior/posterior located mechanical linkage enacting an upward linear movement on a guide pin plunger, thus allowing the side elements to rotate by means of an imposed torque load reaching an intended orientation positively constrained within a grooved profile. The load bearing elements shall be precision machined from Grade 5 Titanium material. Mechanical linkages, fasteners, and springs shall be made from Series 300 Stainless Steel material. All materials shall be surface treated by a chemical passivation process enabling maximum corrosion resistance for use in salt water. 
         [0026]    It is an object of the present invention to provide an ankle joint prosthesis which is a prosthetic adaptive sports ankle that can function with one central core and multiple interchangeable medial and lateral side elements, each pair unique of grooved profiles for various sports applications. 
         [0027]    It is an object of the present invention to provide an ankle joint prosthesis that has a pair of unique mechanical linkages, which when engaged translates a linear motion directing a guide pin on a grooved profile allowing the medial and lateral side elements to rotate to an orientation held in place by spring and mechanical constraint. 
         [0028]    It is an object of the present invention to provide an ankle joint prosthesis that has a unique mechanical linkage centrally located in the anterior and posterior of the central core so that the ankle joint prosthesis is applicable for either the lateral or medial side foot use without modification. 
         [0029]    It is an object of the present invention to provide an ankle joint prosthesis that has unique grooved profile designs for specific sports that will allow the user to transition throughout the ankle&#39;s required range of motion when engaged in aquatic or equestrian activity. 
         [0030]    It is an object of the present invention to provide an ankle joint prosthesis which is made of water proof and corrosion resistant materials, and is capable of withstanding the impact and moment forces of dynamic occurrences, thus shall be precision machined and fabricated from Grade 5 Titanium and Series 300 Stainless Steel material. 
         [0031]    It is an object of the present invention to provide an ankle joint prosthesis which allows the user during aquatic activity to easily transition (from a terrestrial bipedal locomotion orientation to a plantar flexion orientation, and return to a terrestrial bipedal locomotion orientation) to and from the water without having to become stationary and manually rotate and lock the ankle into position by hand, which enables the water sports enthusiast improved confidence and safety during ingress and egress at the aquatic and terrestrial boundary. 
         [0032]    It is an object of the present invention to provide an ankle joint prosthesis which allows the user during equestrian activity to easily transition (from a terrestrial bipedal locomotion orientation to a dorsal flexion orientation, and return to a terrestrial bipedal locomotion orientation) when in the saddle seat and stirrup without having to manually rotate and fix the ankle into the desired orientation by hand, which enables the equestrian enthusiast proper weight distribution providing improved balance and stability. 
         [0033]    It is an object of the present invention to provide an ankle joint prosthesis which is compatible with prosthetic industry standard attachment components for attachment to an artificial leg and an artificial foot. 
         [0034]    It is an object of the present invention to provide an ankle joint prosthesis for which one size fits all users, and is applicable for lateral or medial side leg/foot use without modification to the affecting mechanical linkage&#39;s location. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0035]      FIG. 1  Perspective Exploded View, Ankle Joint Prosthesis 
           [0036]      FIG. 2  Detailed Parts Exploded View, Ankle Joint Prosthesis 
           [0037]      FIG. 3  Medial Side Elevation, Fully assembled Ankle Joint Prosthesis, in position suitable for walking or running. 
           [0038]      FIG. 4  Medial Side Elevation, Fully assembled Ankle Joint Prosthesis, in plantar flexion position suitable for aquatic activity. 
           [0039]      FIG. 5  Medial Side Elevation, Fully assembled Ankle Joint Prosthesis, in dorsal flexion position suitable for equestrian activity. 
           [0040]      FIG. 6  Lateral Side Elevation, Aquatic Grooved Profile 
           [0041]      FIG. 7  Lateral Side Elevation, Surf Grooved Profile 
           [0042]      FIG. 8  Lateral Side Elevation, Equestrian Grooved Profile 
           [0043]      FIG. 9  Fully assembled Ankle Joint Prosthesis attached to artificial leg and artificial foot. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0044]    Referring to  FIG. 1 , which illustrates an exploded perspective view of the embodiment of the present ankle joint prosthesis. The ankle joint embodiment generally is comprised of six key components; a central core element  100 , an anterior mechanical linkage  200 , a posterior mechanical linkage  300 , a central axis mechanical linkage  400 , a medial side element  500 , and a lateral side element  600 . 
         [0045]    Referring to  FIG. 2 , the central core element  100  of  FIG. 1  comprises an upper region  101  and lower region  102 , of which the upper region  101  is precision machined into a diametrical hollow pylon designed in length and outer diameter to be compatible with 30 mm prosthetic industry tube clamp adaptor components. The lower region  102  serves as the housing for the mechanical linkage&#39;s  200 ,  300 , and  400 , and transitions to a generally shaped rectangular geometry comprising the central core anterior face  103 , central core medial face  104 , and central core lateral face  105 . The central core medial face  104  and central core lateral face  105  are of mirror image. The central core posterior face  111  transitions over the circular counterbore  112  housing to a flat face. 
         [0046]    Referring to  FIG. 2 , central core medial face  104  comprises a medial radial groove face  122  down to the central core shoulder  106 , which extends perpendicular from the medial and lateral faces encircling the torsion spring housing counterbore  107  and the central axis circular bore  109 . The lower section of the central core shoulder  106  spans the width of the central core element  100 . The torsion spring housing counterbore  107  penetrates the central core medial face  104 . Torsion spring housing counterbore  107  is a flat-bottomed counterbore. The central axis circular bore  109  penetrates the entirety of the central core element  100  body along the x-axis. The central core medial face  104  is precision machined through to form a slot  110  oriented 70 degrees from the central axis circular bore  109  y-axis plane which allows the posterior mechanical linkage  300  guide pin  301  to move; the slot  110  opening length being equal to the maximum stroke of the posterior mechanical linkage  300 . 
         [0047]    Referring to  FIG. 2 , circular bore  117  on central core  100  lower region  102  medial face  104  originating on the posterior radial side of the lower outer central core shoulder  106 , directed through and penetrating the torsion spring housing counterbore  107  and  108  at the vortex of circular counterbore  112  centerline axis. 
         [0048]    Referring to  FIG. 2 , the central core  100  of  FIG. 1  comprises an upper region  101  and lower region  102 . The lower region  102  of the anterior face  103  transitions to a generally flat face comprising circular bores for the anterior mechanical linkage  200  down to the central shoulder body  106  comprising the central axis mechanical linkage  400 . 
         [0049]    Referring to  FIG. 2 , circular counterbores  114 ,  115 , &amp; circular bore  116  are along the same axis centerline originating on central core  100  lower region  102  anterior face  103 . The centerline of circular counterbores  114 ,  115 , &amp; circular bore  116  being perpendicular to the central axis midpoint. Circular bore  116  penetrates the central core posterior face, whereas circular counterbore  114  is larger than circular counterbore  115 , neither penetrating beyond the central axis circular bore  109  plane. 
         [0050]    Referring to  FIG. 2 , circular bore  112  on central core  100  lower region  102  anterior face  103  lower central core shoulder  106  central axis midpoint, at the 250 degree mark passing through the center of the central axis circular bore  109  of central core  100  a specific length very near, but not penetrating the top of the central core posterior face  111 . Circular counterbore  112  is a flat-bottomed counterbore. Circular bore  113  passes along the same centerline as circular bore  112 , however, penetrating the central core posterior face  111 . 
         [0051]    Referring to  FIG. 2 , the central core  100  of  FIG. 1  comprises an upper region  101  and lower region  102 . The lower region  102  of the posterior face  111  slopes across circular bore  113 , transitions over a chamfered edge which encapsulates the posterior mechanical linkage  300  to a flat face comprising circular bore  116 , the posterior stop  120 , and key slot  121 , down to the central core outer lower shoulder body  106 . 
         [0052]    Referring to  FIG. 2 , the anterior mechanical linkage  200  of  FIG. 1  comprises an assembly utilizing a custom designed self-locking implanted cotter detent pin of which precision-machined characteristics are crucial to the invention. The self locking implanted cotter detent pin of its own design is not a patentable design in this invention; however its customized application for the anterior mechanical linkage  200  is crucial. The precision machined characteristics of the anterior mechanical linkage  200  comprises a head  201  designed specifically to physically constrain the anterior mechanical linkage compression spring  204  within circular counterbore  115 , and limit the linear stroke of the self locking implanted cotter  206 , which is of a critical effective measurement. Another precision machined characteristic crucial to the invention is the plunger saddle  205 . The plunger saddle  205  is designed with a 45-degree slope so as to translate linear horizontal motion affecting an upward stroke of a precise measurement to the posterior mechanical linkage  300 . The self-locking implanted cotter detent pin  206  is physically restrained within key slot  120  of posterior face  111  to prevent the anterior mechanical linkage  200  from retracting or rotating within circular bore  116 . 
         [0053]    Referring to  FIG. 2 , the posterior mechanical linkage  300  of  FIG. 1  comprises an assembly of which precision machined characteristics are crucial to the invention. Precision dimensions regarding diameter, length, and bore location are crucial for the posterior mechanical linkage to fit within circular counterbore  112  and circular bore  113  and function properly in tandem with anterior mechanical linkage  200 . The posterior mechanical linkage  300  comprises plunger guide pin  301 , plunger body  302 , plunger compression spring  303 , plunger stem  304 , and plunger ring  305 . 
         [0054]    Referring to  FIG. 2 , the central axis mechanical linkage  400  of  FIG. 1  comprises a medial torsion spring  401 , central axis shaft  403  lateral torsion spring  402 , medial mechanical fastener  404 , and lateral mechanical fastener  405 . The central axis shaft  403  is not designed to be load bearing, is a precision measured length and tapped both ends to allow for mechanical fastening of the medial side element  500  and the lateral side element  600  mechanical fasteners  404  and  405  respectively. 
         [0055]    Referring to  FIG. 2 , since the medial side element  500  and the lateral side element  600  of  FIG. 1  are designed as mirror images of each other. For the purposes of this description, only the lateral side element  600  will be detailed. 
         [0056]    Crucial to the medial/lateral side element designs are the radial dimensions/tolerances from the central axis plane that effect the central axis bore  610 , torsion spring counterbore  611 , groove profile  614 , and the top rim  604  such that interference with the central core  100  is not created. The central axis circular bore  610  is used to allow connection of mechanical fastener  405  through lateral side element  600  to central axis shaft  403 , thus providing the compressive force to anterior mating face  602  when applied to opposing anterior mating face  502 . The torsion spring housing counterbore  611  is a flat-bottomed counterbore; is crucial due to its depth of fit in relation to the length of the central axis shaft  403 , length of the central core shoulder bearing  613 , and body length of the lateral torsion spring  402 . 
         [0057]    Another crucial feature of the medial/lateral side element design is the groove profile  614 , which defines the groove working curve  615  and the groove inner profile  616  dimensions. The invention is applied for use during aquatic and/or equestrian activity. 
         [0058]    Referring to  FIG. 6 , Aquatic grooved profile  614  is designed such that when the posterior mechanical linkage  300  is effectively moved from its least compressed static orientation, the guide pin  301  will translate via slot  110 , then riding within and along the groove working curve  615  effectively allowing the lateral side element  600  to rotate until held in a dwell motion condition at a specific orientation 70 degrees plantar flexion by the combination of the plunger compression spring  303  force and the groove inner profile  616  positive mechanical constraints. 
         [0059]    Referring to  FIG. 7 , Surf grooved profile  614  is designed such that when the posterior mechanical linkage  300  is effectively moved from its least compressed static orientation, the guide pin  301  will travel a specific vertical stroke distance via slot  110 , then can move along the groove working curve  615  in either radial direction effectively allowing the lateral side element  600  to rotate until held in a dwell condition at a specific orientation 70 degrees plantar flexion, or held in a dwell condition at a specific orientation 20 degrees dorsi flexion. 
         [0060]    Referring to  FIG. 8 , Equestrian grooved profile  614  is designed such that when the posterior mechanical linkage  300  is effectively moved from its least compressed static orientation, the guide pin  301  will travel a specific stroke distance constrained in slot  110 , thus able to ride along the groove working curve  615  in either radial direction effectively allowing the lateral side element  600  to rotate until held in a dwell condition at a specific orientation 45 degrees plantar flexion, or held in a dwell condition at a specific orientation 20 degrees dorsi flexion. 
         [0061]    Yet another crucial feature of the medial/lateral side element is the posterior stop  608  and the anterior stop  609 , designed such that the lateral side element shall not rotate beyond specific dwell locations within the groove profile  614 . 
         [0062]    The lateral side element  600  base face  606  is designed to be compatible with prosthetic industry 4-hole adaptor components; anterior base component fastener tapped hole  619  and posterior base component tapped hole  620  are incorporated for this purpose accepting anterior base component mechanical fastener  622  and posterior base component mechanical fastener  623 . Base circular bore  621  is incorporated for the removal of excess material. 
       Assembly of the Invention 
       [0063]    Step 1, assembly of the posterior mechanical linkage  300  into central core element  100  is accomplished by fitting the plunger compression spring  303  over the plunger stem  304  until resting on the plunger body  302 , and then inserting the assembled parts into lower outer central core shoulder body  106  circular counterbore  112  and circular bore  113 . Plunger guide pin  301  is fitted through slot  110  into circular bore  306  and positioned so that plunger guide pin  301  is centered (each side length to be equal from the plunger body  302  centerline) within the plunger body  302 . Plunger stem circular bore  307  must be in the same axis plane as plunger body circular bore  306 . Push posterior mechanical linkage  300  assembly through circular bore  113  so that plunger stem circular bore  307  penetrates the central core posterior face  114 . Insert plunger ring  305  into plunger stem circular bore  307  to complete the installation of the posterior mechanical linkage  300 . 
         [0064]    Step 2, the anterior mechanical linkage  200  is assembled by fitting the head compression spring  203  over the self locking implanted cotter detent  206  and moving the head compression spring  203  past the plunger saddle  205  until resting on the inner head shoulder  202 , and then inserting the assembled parts into circular counterbores  114 ,  115 , and into circular bore  116 . Lift posterior mechanical linkage  300  by pulling plunger ring  305  in the outward &amp; upward direction such that the anterior mechanical linkage  200  can be pushed through circular bore  116  far enough so that the self locking implanted cotter detent  206  is deployed into key slot  121 , thus positively restrained. 
         [0065]    Step 3, the central axis mechanical linkage  400  is assembled by fitting the medial torsion spring  401  upper leg and the lateral torsion spring  402  upper leg into medial torsion spring circular bores  117  and  118  respectively, located inside the torsion spring housing circular counterbores  107  and  108  respectively. The central axis shaft  403  is then fitted into either side of the central axis circular bore  109  equidistance of the central core element  100  midpoint. 
         [0066]    Step 4, the medial side element  500  and the lateral side element  600  are assembled by press fitting the central core shoulder bearings  513  and  613  into torsion spring housing counterbore  511  and  611  respectively. 
         [0067]    Step 5, insert the medial torsion spring  401  lower leg into medial torsion spring circular bore  518  located internal to torsion spring housing counterbore  511  on medial side element  500  inner face  503 . 
         [0068]    Step 6, fit central axis mechanical linkage mechanical fastener  404  into medial side element countersink  517  and through medial side element circular bore  510  into the threaded central axis shaft  403  and tighten such that the medial side element  500  is firmly connected with central axis shaft  403 , and fitted around and onto the central core shoulder  106  such that the posterior mechanical linkage  300  guide pin  301  is fitted into the groove inner profile  516  of medial side element  500 . 
         [0069]    Step 7, insert the lateral torsion spring  402  lower leg into torsion spring leg bore  618  located internal to torsion spring housing counterbore  611  on lateral side element  600  inner face  603 . Next, fit central axis mechanical linkage mechanical fastener  405  into lateral side element countersink  617  and through central axis circular bore  610  into the threaded central axis shaft  403  and tighten such that the lateral side element  600  is firmly connected with central axis shaft  403 , and fitted around and onto the central core shoulder  106  such that the posterior mechanical linkage  300  guide pin  301  is fitted into the groove inner profile  616  of lateral side element  600 , and medial side element  500  anterior mating face  502  is aligned and flat against lateral side element  600  anterior mating face  602 . 
         [0070]    Step 8, fit lateral side element mechanical fastener  622  and  623  through a prosthetic industry 4-hole adaptor component  725  base into anterior base component fastener tapped hole  619  and posterior base component tapped hole  620  respectively, and tighten per component manufacturer torque value instructions such that the 4-hole adaptor component is firmly connected with the lateral side element  600 . Repeat step 8 for the medial side element mechanical fasteners  522  and  523 . 
         [0071]    Step 9, affix a 30 mm prosthetic industry tube clamp adaptor component  750  onto the central core  100  upper region  101  and tighten per component manufacturer torque value instructions. 
         [0072]    Step 10, Referring to  FIG. 9 , Affix the completely assembled ankle joint prosthesis  700  to an artificial foot  800  and an artificial leg  900 . 
       Operation of the Invention 
       [0073]    Referring to  FIG. 9 , Position the ankle joint prosthesis  700  such that the artificial foot  800  is in the “foot flat” o degree orientation for terrestrial bipedal locomotion use. The key feature of the invention is that the ankle joint prosthesis  700  can have its orientation repositioned without the user having to stop activity and manually establish the desired orientation and lock into position. 
         [0074]    For use in an aquatic sports activity, such as; swimming, scuba diving, wade fishing, or triathlon, use the aquatic grooved profile. Walk, run, or jump into the water and depress the anterior mechanical linkage  200 , thus forcing the posterior mechanical linkage  300  to stroke and allowing the medial and lateral side elements  500  and  600  respectively to rotate via torsion force from central axis mechanical linkage  400 , thus positioning the artificial foot  800  into a 70 degree plantar flexion orientation relative to the artificial leg  900 . 
         [0075]    Depress the anterior mechanical linkage  200  by kicking head  201  with the posterior side of the users&#39; heel from the opposite leg to accomplish engagement for a “hands free” interface, otherwise one can pull the posterior mechanical linkage  300  plunger ring  305  to accomplish the same result. 
         [0076]    Transition from an aquatic environment to terra firma is accomplished by simply applying a force through artificial leg  900  to the bottom forefoot of the artificial foot  800 , thus causing a reverse rotation of the ankle joint prosthesis  700  back to the “foot flat” o degree orientation for terrestrial bipedal locomotion use; i.e. no manual manipulation by hand of the ankle joint prosthesis  700  is required. 
         [0077]    For use in an equestrian sports activity, such as; horseback riding, use the equestrian grooved profile. This specific groove profile is designed for use for walking and while riding in a saddle atop a horse. Use of the anterior mechanical linkage  200  is not utilized; however the posterior mechanical linkage  300  is manually pulled upward allowing the medial and lateral side elements  500  and  600  respectively to ride along the working curve of the grooved profile. 
         [0078]    By pulling the posterior mechanical linkage  300  plunger ring  305  upward/outward and applying a force through artificial leg  900  to the bottom forefoot of the artificial foot  800 , artificial foot  800  will rotate to a 20 degree dorsi-flexion “heel down” orientation. 
         [0079]    Transition while in the saddle seat of the ankle joint prosthesis  700  such that the artificial foot returns to the “foot flat” o degree orientation is accomplished by simply lifting the force from the artificial foot  800  forefoot, thus removing force through the artificial leg  900 , causing a rotation of the ankle joint prosthesis  700  via torsion force from central axis mechanical linkage  400  back to the “foot flat” o degree orientation without having to manually rotate and fix the ankle into the desired orientation by hand, which enables the equestrian enthusiast proper weight distribution providing improved balance and stability. 
         [0080]    Transition from the saddle seat to terra firma is accomplished by relieving any pressure to the artificial foot  800  and pulling the posterior mechanical linkage  300  plunger ring  305  upward/outward, thus allowing the medial and lateral side elements  500  and  600  respectively to rotate via torsion force from central axis mechanical linkage  400 , thus positioning the artificial foot  800  into a 45 degree plantar flexion orientation relative to the artificial leg  900  so that the artificial foot  800  can easily be extracted from the saddle stirrup. 
         [0081]    For use in an aquatic sports activity, such as surfing, use the surf grooved profile. Walk or jump into the water and depress the anterior mechanical linkage  200 , thus forcing the posterior mechanical linkage  300  to stroke and allowing the medial and lateral side elements  500  and  600  respectively to rotate via torsion force from central axis mechanical linkage  400 , thus positioning the artificial foot  800  into a 80 degree plantar flexion orientation relative to the artificial leg  900  for swimming or in the kneeling position on the surf board. 
         [0082]    Depress the anterior mechanical linkage  200  by kicking head  201  with the posterior side of the users heel of the opposite leg to accomplish engagement for a “hands free” operational interface, otherwise pull the posterior mechanical linkage  300  plunger ring  305  to accomplish the same result. 
         [0083]    Stand on the surfboard and apply a force through artificial leg  900  to the bottom forefoot of the artificial foot  800 , thus causing a reverse rotation of the ankle joint prosthesis  700  back to the “foot flat” o degree orientation. To stabilize your stance and obtain a squatting forward position, simply pull the posterior mechanical linkage  300  plunger ring  305  upward/outward and apply a force through artificial leg  900  to the bottom forefoot of the artificial foot  800 , artificial foot  800  will rotate to a 20 degree dorsi-flexion orientation. 
         [0084]    Transition of the ankle joint prosthesis  700  such that the artificial foot returns to the “foot flat” o degree orientation is accomplished by simply lifting the artificial foot  800  forefoot, thus removing force through the artificial leg  900 , causing a rotation of the ankle joint prosthesis  700  via torsion force from central axis mechanical linkage  400  back to the “foot flat” o degree orientation without having to manually rotate and fix the ankle into the desired orientation by hand. 
         [0085]    Transition from an aquatic environment to terra firma if in the 80 degree plantar flexion orientation is accomplished by simply applying a force through artificial leg  900  to the bottom forefoot of the artificial foot  800 , thus causing a reverse rotation of the ankle joint prosthesis  700  back to the “foot flat” o degree orientation for terrestrial bipedal locomotion use; i.e. no manual manipulation by hand of the ankle joint prosthesis  700  is required.