We have three different designs for a partial foot prosthesis. Depending upon the level of amputation each design has different characteristics accordingly. We consider an amputation to be a Partial foot amputation when all the Metatarsal heads are removed. This is when the lever arm of the foot is compromised.
The Function of the partial foot prosthesis is to replace the section of the limb, so the patient can increase the time spent on the extremity. Inherently reducing the increased time being spent on the contralateral limb.
If the patient has a lesser amputation level, one or more metatarsal heads and/or toes remaining, they still have an effective lever for balance and propulsion. At this level we recommend one of our AFO designs and for the practitioner to add a toe filler as needed. We do not make a toe filler for these.
Chopart: This patient has lost the forefoot and mid-foot. Commonly at this level, the patient’s heel rises putting the Talocrural joint into extreme plantarflexion.
There is no longer any forward lever arm of the foot and propulsion is gone. The time on the extremity is severely shortened. It is common to see the hind-foot contractions the limit the range of motion; or the surgeon has fixed the Talocrural joint to avoid collapse.
It is our experience that this level of amputation, with at least a ten degree available range of motion, The patient excels with this design. Returning the function of propulsion and standing balance of amputated leg. This is evident when the patient is observed spending more time on this extremity and less on the contralateral. The prosthesis is functionally reducing the overuse of the contralateral limb.
This design offers a dorsal section that extends above the ankle, while allowing Talocrural motion to occur within the socket of the prosthesis. In some cases the patient can donn the prosthesis while the shoe wear is still on the foot section.
When casting for this design the practitioner should be cautious to set the Talo-Crual joint into a sub-talor neutral alignment. accommodation of the heel height of the shoe is not necessary but should be noted, considering that the prosthetic metatrarsal heads will be setting the remaining mid-foot down and supinated.
This distall aspect being supinated to reach Sub-Talor neutral positioning. This Needs to included the practitioner casting to put the internal/external rotation of the hind foot in 7 degrees of toe out in relation to the knee. The practitioner should also insure that the patient has available Dorsi/Plantar flexion from the position casted. Cast needs to include the patella and the residual limb needs to be set with seven degrees of toe out in relation to the knee.
Liz-Franc: This patient has lost the forefoot and most of the mid-foot. Commonly at this level, the patient is Not able to use the mid-foot for standing balance. At this level the leverarm of the foot for propulsion is gone. The time on the extremity is severely shortened. It is common to see the hind-foot in severe plantar-grade position and contractions the limit the range of motion.
It is our experience that this level of amputation, with at least a ten degree available range of motion, excels with this design. Returning the function of propulsion and standing balance of amputated leg. This is evident when the patient is observed spending more time on this extremity and less on the contralateral. leg can be compensated for by the contralateral limb.
This design offers a dorsal section over the remining midfoot and ankle. This anticipates the patient’s need to donn the prosthesis and then to donn the shoewear each time.
When casting for this design the practitioner should be cautious to set the Talo-Crual joint into a sub-talor neutral alignment. With accommodation of the heel height of the shoe to be worn, considering that the prosthetic metatrarsal heads will be setting the remaining mid-foot down and supinated.
This distall aspect being supinated to reach Sub-Talor neutral positioning. This also allows for the plantar midfoot of the prosthesis to be narrow to fit into shoewear better. The practitioner should also insure that the patient has available Dorsi/Plantar flexion from the position casted. Cast needs to include the patella and the residual limb needs to be set with seven degrees of toe out in relation to the knee.
Trans-metatarsal: This patient has lost the forefoot but still has the mid-foot. Commonly at this level, the patient is able to use the mid-foot to create a compensation for standing balance. With the metararsals ALL missing, the leverarm of the foot for propulsion is almost completely compromised. The time on the extremity is shortened because of this lack of propulsion. The same as a patient with a deficit Calf strength.
It is our experience that the function of propulsion of one leg can be compensated for by the contralateral limb. Many times the trans metatarsal level amputation patient, will reject the cumbersomeness of a tibial tubrical height prosthesis. This is because the resulting functional increase is not as high.
This design offers an open dorsal section over the midfoot and ankle. This anticipates the patients shoe to secure them into the prosthesis. This also accommodate for not having to remove/reapply the shoe when donning the prosthesis.
When casting for this design the practitioner should be cautious to set the Talo-Crual joint into a sub-talor neutral alignment. With accommodation of the heel height of the shoe to be worn, considering that the prosthetic metatrarsal heads will be slightly lower then the distal aspect of the remaining mid-foot. This distall aspect can also be supinated slightly to reach Sub-Talor neutral positioning. The practitioner should also insure that the patient has available Dorsi/Plantar flexion from the position casted. Cast needs to include the patella and the residual limb needs to be set with seven degrees of toe out in relation to the knee.
