# Foreword
The ICRC polypropylene technology Since its inception in 1979, the ICRC's Physical Rehabilitation Programme has promoted the use of technology that is appropriate to the specifi c contexts in which the organization operates, i.e., countries aff ected by war and low-income or developing countries.
Th e technology must also be tailored to meet the needs of the physically disabled in the countries concerned.
Th e technology adopted must therefore be:
- durable, comfortable, easy for patients to use and maintain; - easy for technicians to learn, use and repair;
- standardized but compatible with the climate in diff erent regions of the world; - low-cost but modern and consistent with internationally accepted standards; - easily available.
Th e choice of technology is of great importance for promoting sustainable physical rehabilitation services.
For all these reasons, the ICRC preferred to develop its own technique instead of buying ready-made orthopaedic components, which are generally too expensive and unsuited to the contexts in which the organization works. Th e cost of the materials used in ICRC prosthetic and orthotic devices is lower than that of the materials used in appliances assembled from commercial ready-made components.
When the ICRC launched its physical rehabilitation programmes back in 1979, locally available materials such as wood, leather and metal were used, and orthopaedic components were manufactured locally. In the early 1990s the ICRC started the process of standardizing the techniques used in its various projects around the world, for the sake of harmonization between the projects, but more importantly to improve the quality of services to patients. Polypropylene (PP) was introduced into ICRC projects in 1988 for the manufacture of prosthetic sockets. Th e fi rst polypropylene knee-joint was produced in Cambodia in 1991; other components such as various alignment systems were fi rst developed in Colombia and gradually improved. In parallel, a durable foot, made initially of polypropylene and EthylVinylAcetate (EVA), and now of polypropylene and polyurethane, replaced the traditional wooden/rubber foot.
In 1998, aft er careful consideration, it was decided to scale down local component production in order to focus on patient care and training of personnel at country level.

# Objective of the manuals
Th e ICRC's "Manufacturing Guidelines" are designed to provide the information necessary for production of high-quality assistive devices.
Th e main aims of these informative manuals are as follows:
- To promote and enhance standardization of ICRC polypropylene technology; - To provide support for training in the use of this technology; - To promote good practice.
Th is is another step forward in the eff ort to ensure that patients have access to high-quality services.

# ICRC Assistance Division/Health Unit Physical Rehabilitation Programme

# Choosing between diff erent designs
Without going into details, some features of diff erent types of AFO are set out below to assist in the choice of design. 

# Introduction
Th e aim of this document is to describe several methods for manufacturing ankle-foot orthoses (AFO), working with the polypropylene technology used at the ICRC's physical rehabilitation centres.

# Casting and rectifi cation
Patient assessment, casting and rectifi cation of positive cast impressions are performed in accordance with prosthetic and orthotic (P&O) standards.
For fl exible AFO, the cast can be taken with 5 degrees of dorsifl exion so as to provide a preload and ensure some spring action.

# Moulding of EVA
A fl exible AFO does not usually require any EVA. However, in cases where it is necessary the procedure described in section 2.1 (page 8) should be followed.

# Orthosis trim line
To achieve the goal of allowing dorsifl exion of the ankle while preventing passive plantar fl exion, there are a number of design options.

# FLEXIBLE AFO

# Mark the trim line as follows:
A Th e top is horizontal, 2 cm below the fi bula head.
B At the ankle, pass 2 cm behind the tip of the malleoli to allow fl exion of the polypropylene.
C At the forefoot, leave the sides of the toes and the head of the metatarsus completely clear and pass the trim line below them. Th is will allow the polypropylene to follow the movement of the metatarso-phalangeal joints.
Pull a stocking over the plaster model.

# Vacuum moulding of the polypropylene
Dust the stocking with talcum powder.
Measurement of the polypropylene sheet:
1 Calf circumference + 10 cm. 2 Instep circumference + 10 cm.
3 Leg and foot length + 10 cm. (See next picture.)
Th ickness 3 mm, 4 mm or 5 mm, depending on the patient's weight.
Manufacturing Guidelines Ankle-Foot Orthosis
Heat the polypropylene at 180 for 20 to 25 minutes, depending on the thickness of the polypropylene and the effi ciency of the oven.
Drape the polypropylene over the plaster model and stick it together along the anterior side.
Tighten the polypropylene around the suction cone by means of a rope or something similar.
Open the vacuum valve.
Cut off the excess PP with a pair of scissors while it is still hot.
Keep the vacuum on until the polypropylene cools down.

# Preparation of the polypropylene shell
Draw the trim line on the polypropylene as described in section 1.2 (page 6).
Following the outline, cut the orthosis with an oscillating saw.
Remove the plastic shell from the plaster model.
Remove the stocking from inside the AFO.
Grind the orthosis trim line and smooth it.
If an EVA has been moulded, transfer the trim line to the EVA and cut off the excess with a pair of scissors.

# Preparation of the straps
For the proximal strap, follow the procedure described in section 2.6 (page 14).
A distal strap might be needed, depending on the capacity of the patient's shoe to hold the foot inside the orthosis. If this is needed, follow the procedure described in section 2.7 (page 15).

# Initial fi tting and fi nishing
If EVA is used, glue it partially inside the orthosis.
Th e initial fi tting is performed according to P&O standards.
Carry out the required modifi cation on the polypropylene and smooth the trim line.
Glue the EVA completely inside the polypropylene, cut off the surplus and smooth the trim line.
RIGID AFO 2

# Moulding of EVA
EVA (6 mm) may be moulded prior to the draping of the polypropylene, for the following reasons: - to improve comfort;
- to prevent skin breakage in patients with sensation loss;
- for orthoses used at night.
Follow the procedure described below or, if the case does not require EVA, go on to the next section.
Position the plaster model with the forefoot pointing downwards.
Measurement of the EVA sheet:
- width, instep circumference;
- length, that of the plaster model (leg + foot); - thickness, 6 mm.
Heat the EVA at 120 for 3 to 5 minutes, depending on the effi ciency of the oven.
Drape the EVA manually over the plaster model and hold it in place until it has cooled completely.
Cut off the excess with a cutter or a pair of scissors.
Staple the EVA onto the front of the plaster model.

# Orthosis trim line

# "Standard" trim line
Mark the trim line as follows:
A Th e top must be horizontal, 2 cm below the fi bula head.
B At the ankle, pass the line 1 cm anterior to the tip of the malleoli.
C At the forefoot, leave the sides of the toes and the head of the metatarsus completely clear and pass the trim line below them. Th is will allow the polypropylene to follow the movement of the metatarso-phalangeal joints.

# Trim line to correct forefoot adduction
Forefoot adduction is common in cases of clubfoot.
Mark the trim line as follows:
A Th e top must be horizontal, 2 cm below the fi bula head.
B Increase coverage of the lateral midfoot, passing in front of the cuboid, to enlarge the area of pressure.
C At the forefoot, the line must be proximal to the 5th metatarsal head.
D Decrease coverage of the medial mid-foot at the navicular/malleoli, to facilitate donning.
E At the forefoot, cover the medial side of the metatarsal head and toe, to correct forefoot adduction.

# Trim line to correct forefoot abduction
Forefoot abduction is oft en seen in cases of cerebral palsy.
Mark the trim line as follows:
A Th e top must be horizontal, 2 cm below the fi bula head.
B Decrease coverage at the level of the lateral malleoli, to ease donning.
C At the forefoot, the line must be distal to the 5th metatarsal head, to avoid metatarsus abductus.
D Increase coverage of the medial mid-foot at the level of the navicular, to increase mid-foot support.
E At the forefoot, the line must be proximal to the 1st metatarsal head.

# Plastic reinforcement
Th e AFO may need reinforcement, especially at ankle level. If necessary, use one of the following methods; otherwise go on to the next section.

# Double layer of polypropylene
A second layer of polypropylene covering the ankle and the foot is moulded at the same time as the main layer.
Cut a piece of polypropylene:
- thickness, 3 mm; - width, instep circumference;
- length, foot length + 10 cm Grind the last 3 cm at the proximal end to gradually reduce the thickness of the polypropylene.
Th e two layers are heated at the same time.
Th e reinforcement is placed on the plaster model, then the second layer is vacuum-moulded immediately to obtain a perfect seal between the two.
A double layer of polypropylene has the disadvantage of reducing fl exibility of the forefoot in relation to the metatarso-phalangeal joint.

# Channels in the polypropylene
Th e presence of channels in the plastic signifi cantly improves its strength. Th ere are several ways of making these channels.
Cut two strips of EVA:
- thickness, 6 mm;
- width, 7 mm; - length, 15 cm.
Grind both distal and proximal ends to gradually reduce the thickness of the EVA.
Pull a stocking over the plaster model.
Glue the strip lightly onto the stocking.
Th e more anterior the position of the channel, the more the AFO will resist dorsifl exion of the ankle.
Reinforcements prolonged along the side of the mid-foot increase the volume of the orthosis so that it may no longer fi t into the patient's shoe.

# Vacuum moulding of the polypropylene
If this has not yet been done, pull a stocking over the plaster model. For maximum effi ciency, the EVA used to make channels in the polypropylene must not be covered with a stocking.
Follow the procedure described in section 1.3 (page 6), taking into account the presence or absence of a double layer of polypropylene (section 2.3.1, page 12).

# Proximal strap
Use a ready-made Velcro strap 40 mm wide, or make a strap with Perlon webbing or some other strong material.
With a large tubular rivet, fi x the belt holding the loop on the medial side, 1.5 cm below the proximal trim line.
Th e loop should be placed on the polypropylene and not be in contact with the patient's leg.

# Preparation of the polypropylene shell
Draw the trim line on the polypropylene as described in section 2.2 (page 9).
Cut the orthosis with an oscillating saw, following the outline.
Remove the plastic shell from the plaster model.
Remove the stocking from inside the AFO.
Grind the orthosis trim line and smooth it.
If EVA has been moulded beforehand, transfer the trim line to the EVA and cut off the excess with a pair of scissors.
Insert the belt through the loop to measure the required length.
Fix the strap with a large tubular rivet on the lateral side. Make sure the strap is perfectly horizontal before fi xing it.
Cover the surface of the strap in contact with the patient's leg with 3 mm EVA.
Fix the strap with a large tubular rivet on the lateral side. Make sure the strap is perfectly horizontal before fi xing it.
Cover the surface of the strap in contact with the patient's leg with 3 mm EVA.

# Distal strap
You must choose between a distal strap and an instep strap. Th e latter has the advantage of holding the calcaneum fi rmly inside the orthosis (equinus correction).
Use a Velcro strap 25 mm wide.
With a large tubular rivet, fi x the belt holding the loop on the medial side, 4 cm above the malleoli.
Th e loop should be placed over the polypropylene and not be in contact with the patient's leg.

# Instep strap
Use a Velcro strap 25 mm wide.
Two techniques are presented, depending on whether the back of the foot is in a neutral position or needs a valgus/varus correction.

# Neutral position
With a large tubular rivet, fi x the belt holding the loop on the medial side, at an angle of 45 passing through the posterior distal tip of the calcaneum.
Th e loop should be placed over the polypropylene and not be in contact with the patient's leg.
Insert the belt through the loop to measure the required length.
Fix the strap with a large tubular rivet on the lateral side, at the same angle of 45.
Cover the surface of the strap in contact with the patient's leg with 3 mm EVA.

# Varus/valgus correction
Th e strap will pass through a slot cut in the polypropylene.
Th e slot is cut on the lateral side for varus correction and on the medial side for valgus correction.
Mark the position of the slot 40 mm from the back of the foot and perpendicular to a line drawn at an angle of 45 passing through the posterior distal tip of the calcaneum.
Th e slot should be 30 mm long.
Make holes along the slot axis with a drill fi tted with a 4 mm bit.
With a cutter, connect the holes with each other.
Finally, smooth the trim line with a fi le.
Th e loop is placed on the medial side for varus correction and on the lateral side for valgus correction.
Fix the belt holding the loop with a large tubular rivet, at an angle of 45 passing through the posterior distal tip of the calcaneum.
Th e loop should be placed over the polypropylene and not be in contact with the patient's leg.
Insert the belt through the slot on one side and through the loop on the other side to measure the required length.
Fix the strap with a large tubular rivet just outside the slot.
Cover the surface of the strap in contact with the patient's leg with 3 mm EVA.

# AFO WITH TAMARACK FLEXURE JOINT TM

# Initial fi tting and fi nishing
If EVA foam is used, glue it temporarily inside the orthosis.
Th e initial fi tting is performed in accordance with P&O standards.
Carry out the required modifi cations on the polypropylene and smooth the trim line.
Glue the EVA completely inside the polypropylene, cut off the surplus and smooth the trim line.

# Moulding of EVA
Follow the procedure described in section 2.1 (page 8), or go on to the next section if EVA is not required.

# Orthosis trim line
Follow the procedure described in section 2.2.1 (page 9).

# Plastic reinforcement
Posterior reinforcement for greater plantar fl exion control is required when the orthosis is intended to prevent plantar fl exion (not fully described below).
Follow the procedure described below, or go on to the next section if plantar fl exion is left free.
A second layer of polypropylene for positioning at the level of the Achilles tendon is moulded at the same time as the main layer.
Cut a piece of polypropylene:
- thickness, 5 mm; - width, 2 cm; - length, 7 cm.
First the reinforcement (heated at the same time as the polypropylene) is placed on the plaster model, then the second layer is vacuum-moulded immediately to obtain a perfect seal between the two layers.
Use the moulding dummies to form a snugly fi tting cavity for the Tamarack Flexure Joint TM .
Nail them vertically onto the plaster model so that the midpoint is located on the ankle axis.

# Installation of Tamarack Flexure Joint TM
On the plaster model, mark the position of the joint axis:
- laterally, at the apex of the malleoli;
- medially, slightly posterior to the distal tip of the malleoli.
Make sure that the joints are at the same level on both sides.

# Vacuum moulding of the polypropylene
Follow the procedure described in section 1.3 (page 6), taking into account the presence or absence of a posterior reinforcement (section 3.3, page 18).
Pull a nylon stocking (cotton stockinet is too thick) over the plaster model.

# Preparation of the polypropylene shell
Draw the trim line on the polypropylene as explained in section 3.2 (page 18).
Cut only the contour of the orthosis with an oscillating saw. Do not cut along the separation between foot section and calf section.
Remove the plastic shell from the plaster model.
Extract the moulding dummies and the stocking from inside the AFO.
Draw the separation line between the foot section and the calf section:
- Mark the middle of the cavities created by the dummies. - Draw a "V" anterior to the midline of each cavity. Ensure that the "V" does not extend backwards past the centre of the cavity.
For AFO with plantar fl exion control, draw a horizontal line posterior to the marks joining the two sides.
For AFO with free plantar fl exion, draw a "V" posterior to the midline of each cavity. Ensure that the "V" does not extend forward past the centre of the cavity.

# Correct Incorrect
Drill holes at the dimples left by the holes in the moulding dummies:
- 5 mm for large size; - 4.5 mm for small size.
Use a thin-bladed saw (1/16'' blade kerf or less) to separate the foot section from the calf section.
Do not use an oscillating saw because too much material is lost along a ragged, wide cut line.
Smooth the trim line edge with a hand deburring tool or a piece of glass. Do not grind the trim line because this will reduce fl exure coverage and reduce the ability of the cavity to anchor and control the fl exure eff ectively.
Insert the Tamarack Flexure Joint TM and secure with metal fasteners and anchoring screws.
Depending on the thickness of the polypropylene, it may be necessary to adjust the length of the screws if the ends protrude inside the AFO.

# Preparation of the straps
For the proximal strap, follow the procedure described in section 2.6 (page 14).
In some cases the patient might need a distal strap. If so, follow the procedure described in section 2.7 (page 15).

# Initial fi tting and fi nishing
If EVA foam is used, glue it temporarily inside the orthosis.
Th e initial fi tting is performed in accordance with P&O standards.
Carry out the required modifi cations on the polypropylene and smooth the trim line.
Glue the EVA completely inside the polypropylene, cut off the excess and smooth the trim line.
Glue the fl exure anchoring screws with a removable thread-locking compound (Loctite). EVA (6 mm) may be moulded prior to draping of the polypropylene:

# AFO ANTITALUS ANTERIOR SHELL
- to improve comfort;
- to prevent skin breakage for patients with sensation loss.
Do not cover the foot, to avoid an increase of volume which may prevent the patient from wearing normal shoes.
Follow the procedure described below, or go on to the next section if the case does not require EVA.
Position the plaster model with the forefoot pointing upwards.
Cut a piece of EVA:
- width, calf circumference;
- length, leg length;
- thickness, 6 mm.
Heat the EVA at 120 for 3 to 5 minutes, depending on the effi ciency of the oven.
Drape the EVA over the plaster model manually and hold it in place until it has cooled completely.
Cut off the excess with a cutter or a pair of scissors.
Grind the distal trim line to gradually reduce its thickness.
Staple the EVA onto the back of the plaster model.
Mark the orthosis trim line as follows:
A Th e top must be horizontal, 2 cm below the tibial tubercle.
B On the leg, 1 cm posterior to the mid-line.
C On the ankle, at the top of the malleoli to facilitate donning. D On the forefoot, clear the sides and top of the toes and the head of the metatarsus completely, passing below them. Th is will allow the polypropylene to follow the movement of the metatarsophalangeal joints. 

# Plastic reinforcement
Th e presence of channels in the plastic signifi cantly improves its strength. Th ere are several ways of making these channels.
Cut two strips of EVA:
- thickness, 6 mm; - width, 10 mm; - length, 20 cm.
Grind both distal and proximal ends to gradually reduce their thickness.
Glue the strips onto the plaster model, 1 cm anterior to the lateral and medial longitudinal axes.
Reinforcements prolonged along the side of the mid-foot increase the volume of the orthosis so that it may no longer fi t into the patient's shoe.

# Vacuum moulding of the polypropylene
Th e procedure described below ensures uniform thickness of the polypropylene all over the orthosis. Do not try to make a single seam on the anterior side, because the creases gathering at the ankle will make it necessary to stretch the polypropylene too thinly.
If this has not yet been done, pull a stocking over the plaster model. For maximum effi ciency the EVA used to channel the polypropylene must not be covered with a stocking.
Dust the stocking with talcum powder.
Measurement of the polypropylene sheet:
1 Calf circumference + 10 cm. 2 Instep circumference + 10 cm.
3 Leg and foot length + 10 cm.
PP thickness: 4 mm or 5 mm, depending on the patient's weight.
Heat the polypropylene at 180 for 20 to 25 minutes, depending on the thickness of the polypropylene and the effi ciency of the oven.
Drape the polypropylene over the plaster model and stick it together along the posterior side and under the foot.
Tighten the polypropylene around the suction cone with a rope or something similar.
Open the vacuum valve.
Cut off the excess with a pair of scissors while the polypropylene is still hot.
Keep the vacuum on until the polypropylene cools down.

# Preparation of the polypropylene shell
Draw the trim line on the polypropylene as explained in section 4.2 (page 23).
Cut the orthosis with an oscillating saw, following the outline.
Remove the plastic shell from the plaster model.
Remove the stocking from inside the AFO.
Grind the orthosis trim line and smooth it.
If EVA has been moulded beforehand, transfer the trim line to the EVA and cut off the excess with a pair of scissors.

# Initial fi tting
If EVA foam is used, glue it temporarily inside the orthosis.
Th e initial fi tting is performed in accordance with P&O standards.
It is oft en necessary to fl are the polypropylene at the posterior part of the heel in order to facilitate donning and to avoid painful contact with the edge of the plastic.

# Preparation of the straps
For the proximal strap, follow the procedure described in section 2.6 (page 14).
In some cases the patient might need a distal strap. If so, follow the procedure described in section 2.7 (page 15).

# Finishing
Carry out the required modifi cations on the polypropylene and smooth the trim line.
Glue the EVA inside the polypropylene, cut off the surplus and smooth the trim line.

# Casting and rectifi cation
As patient assessment, casting and rectifi cation of the positive cast impressions are performed in accordance with P&O standards, below we describe only specifi c aspects related to an AFO with an FMAJ.
For a jointed AFO with an FMAJ, the cast should be taken with the foot in a neutral position. At an angle of 90, we recommend that a 5-8mm EVA be placed under the heel to provide pre-positioning of the foot shell so as to ensure that it fi ts better in a standard shoe.
Th ere are several methods of defi ning the compromise ankle axis (CAA) for the ankle joint. Here we describe one way of achieving the best result for this type of joint: it is commonly used when manufacturing stirrups.
Th e apex of the lateral malleolus (ALM) should be taken as the main reference point for fi nding the CAA, with the basis of the medial malleolus (AMM) serving as an auxiliary reference point.
It is presumed that these and the other usual points of reference are properly marked on the patient during casting.
Remove the cast from the patient's foot and check whether your marks have been properly transferred to the negative.
Punch a 3mm hole at the ALM.

# Warning:
Use an awl for punching -drilling a wet cast may damage your negative! 905 -8 mm 3 mm hole Prepare a steel bar 3mm, L=200mm (an electrode welding rod can be used), make sure that it is perfectly straight and sharpen it at one end.
Place the negative vertically on the bench (with same pad under the heel), use a plumb line to check that it is absolutely vertical and fi x in this position.
Insert the steel bar into the ALM hole and punch a hole at the AMM keeping the bar horizontal (parallel to the bench).
Check that the bar is absolutely horizontal -its distance to the bench surface should be exactly the same at the lateral and medial sides.

# L=M

# Warning:
To correct the position of the axis move the medial side only!
On the transversal plane the CAA generally follows the natural lateral rotation of 5-7.
Checking the rotation angle:
Draw the line of progression and, as before, the knee-axis (at 90) on the surface of the bench and place the negative cast on top of it for control purposes. Visually check the ankle-axis (steel rod) and knee-axis line.

# angle = 5-7W
arning: To correct the position of the axis move the medial side only! Aft er correcting the position of the axis, reinforce the negative around the metal bar with four or fi ve layers of POP bandage.
Remove the 3mm steel rod from the negative and carefully enlarge both holes with an awl to approx. 6mm.
Prepare an L-shaped arbour and place it in the negative. Grease the entire length of the bushing adjustment bar and fully insert it in the negative.

# L M
Th en close the anterior opening of the negative with POP bandage and fi ll up with POP in accordance with general practice.
Aft er solidifi cation of the POP, carefully remove the negative, cutting it, as shown below, at both the medial and lateral sides.
Rectify the positive in accordance with general P&O practice.
Draw the trim lines to make it easier to imagine the fi nal product.
Remove the POP from the threaded ends of the bushing adjustment bar, apply some grease and assemble both interior bushings.
Form the aluminium side pieces for both the medial and the lateral side in accordance with the positive's shape, bending them with contouring tools. Avoid bending them sharply -smooth curves only! It is unnecessary to replicate the shape precisely -a gap of 3-4mm is acceptable.
Bevel the edges as shown in the picture -don't make the edges too sharp! gap 3-4 mm bevel Attach the side pieces to the interior bushings, assemble the exterior bushings, and then fi x the side pieces onto the positive with small nails aft er ascertaining that they are correctly positioned.
Fill up the space between the joints and the positive evenly with POP and then smooth with wire mesh.
If necessary, cut the ends of the bar that stick out of the bushings and fi le the burrs off .
Fix the positive in the draping cone and carry out the usual procedures in preparation for draping the PP.
Prepare the Achilles tendon padding -a piece of EVA 80x20x6mm -bevel the edges and paste it over the nylon stocking, as shown, using contact glue. Aft er the PP has been draped this area will serve as the plantar fl exion stopper. At the same time, the soft padding will protect the Achilles tendon from rubbing against the trim lines.
Th e same technique, using PP instead of EVA, is oft en used in order to reinforce the plantar fl exion stopper.
Pull nylon stockings over the positive -be careful not to damage the nylon on the sharp edges of the bushings.

# EVA 80x20x6 mm
Drape the PP in accordance with usual P&O practice.
Th e thickness of the PP is chosen according to the function of the AFO and the patient's weight.
Draw and cut the trim lines. Carefully knock out and remove the POP and arbour from the shell. Be careful not to damage the bushing adjustment bar and other components.
Carefully fi le the PP over the bushings down to the level of the bushings, as shown. Th ese surfaces have to be fl at and parallel.
Th e hole that appears as a result will serve to remove the bushing adjustment bar and to fi x the foot shell with bolts.
Clean the thread and keep rotating the bushing adjustment bar until it comes out through the hole on one side, so the joint on the opposite side is released.
Remove both joints and the bushing adjustment bar from the PP shell.
Dismantle the bushing adjustment bar, clean it and keep for further use.
Clean away the remaining POP from the shell, ankle joints and Achilles tendon padding.
Roughen the inner surface of the PP with sandpaper and , using contact glue, paste the padding back in place.
Put both joints back in place; fi x them with foot shell bolts and position properly to mark the rivet holes.
For this operation, you can heat the bent sharp end of the scriber and mark the PP through the prefabricated holes in the joints.
Prepare a special blade for the oscillating cutter, as shown below, for the accurate cutting of complicated curve lines.
 Draw the lines on a standard blade as shown.
Carefully fi le down these parts of the blade.

# Warning:
Do not apply extra force while cutting the PP with this blade -the narrow part breaks easily! Draw the separation line between the foot and the shin shells, cut along it carefully and fi le down the trim lines on both shells.
Assemble the joints temporarily, fi xing them with M3 screws, washers and nuts and then assemble the bushings with brass bolts and attach them to the foot shell.
Prepare the cuff belt and fi x it with a large tubular rivet on the proximal lateral fl ap. Instead of a medial buckle, you can cut a slot through the proximal medial fl ap of a width corresponding to the belt.
Perform fi rst fi tting and functional test with the patient in accordance with general P&O practice: observe the gait pattern, check trim lines, gait deviations, and range of motion of the ankle with the AFO.

# Plantar fl exion
Th e initial range of motion for plantar fl exion is limited by the posterior trim lines -the gap is about 1-2 mm aft er initial cutting. If necessary, you can increase plantar fl exion by fi ling down the trims of the plantar fl exion stopper as shown below.
Note that this is a delicate and irreversible process. Do it in small stages, checking the range of motion with the patient aft er each stage, in order to avoid mistakes.
Estimate the full amount, L, to be cut off -half of it, S, should be fi led away from the shin part and the other half, F, from the foot part.

# L=S+F and S=F
Draw the lines fi rst and then dismantle the foot shell and joints.
Carefully grind down the respective parts of the plantar fl exion stopper and smooth the sharp edges. Assemble the foot shell and again check the range of motion with the patient.

# The design
Based on ICRC fi eld experience and employing PP technology, the following has been designed, and is proposed, as a standard type of ankle joint (see references in the annex).
Free-motion ankle joint (FMAJ) -made of aluminium and usable for any type of AFO or KAFO where ankle-joint motion is required. It is also recommended for very active, or very large, patients, as well as for "heavy duty" purposes (e.g. to correct deformities with contractures, Pes Valgus, Pes Calcaneus, etc.) as an alternative to a fl exure ankle joint.
Th e FMAJ consists of aluminium side pieces, interior and exterior brass bushings and brass bolts for fi xing to the foot shell.
A bushing adjustment bar, which represents the compromise ankle axis, automatically ensures that the side pieces are parallel.
Th e basic set (fi ve pairs + bushing adjustment bar) in adult and children's sizes is produced by CR Equipements, Coppet, Switzerland and is included in the PRP standard list.

# AFO WITH A FREEMOTION ANKLE JOINT

# Dorsal fl exion
In many cases dorsal fl exion is free; therefore there is no need for any stopper and the anterior trim lines are shaped respectively. However, if needed, the anterior parts of the shells (as shown in the picture below) can serve as the dorsal fl exion stopper.
As for plantar fl exion, the initial range of motion for dorsal fl exion is limited by the anterior trim linesthe gap is 1-2 mm aft er initial cutting.
Apply the same process as for plantar fl exion in order to adjust the range of dorsal fl exion.
Carefully fi le down the trim lines, testing the AFO on the patient at each stage.

# dorsal flexion stopper
Aft er achieving the desired range of motion, assemble all the components again.
Replace the M3 screws one by one with copper rivets, 3mm or 4mm depending on the patient's weight and size.
If necessary, shape the foot sole with EVA for a better fi t in a standard shoe.
Finish the edges of the trim lines, openings, etc. as usual.
In order to avoid the bushing bolts working loose, apply some "Loctite" and/or punch them slightly from inside.
Th e AFO is ready for delivery. List of manufacturing materials