Checking the Orthosis’ Alignment – Statically

Check if the length of the foot piece corresponds to the inner shoe length. If it doesn’t this is not the case, the foot piece can slip in the shoe and the maximum leverage ratios cannot be used. If the foot piece is too long, shorten it. If the foot piece is too short, i.e. the foot with orthosis does not fill the volume of the shoe, compensate for the missing volume.

Check if the pitch of the foot piece and the shoe is identical. If this is not the case, the tibia inclination (the angle between the lower leg and the ground) is not optimal and a readjustment of the system ankle joint is necessary. In the case of a KAFO, the knee joint angle must also be readjusted.

Check if the toe spring of the foot piece and the shoe is identical. If this is not the case, toe spring and/or volume problems can occur in the orthosis, which can lead to compensation mechanisms.

Digression Supportive Area
With a quadruped, all four feet limit the supportive area. The quadruped is in a stable balance when the body’s centre of gravity is above this surface. The plumb bob should therefore fall from the body’s centre of gravity into this area.

Digression Supportive Area
With a biped, the feet limit the supportive area as well. This area is significantly smaller than that of a quadruped, which makes it more difficult to achieve and maintain a stable balance. Even with a small shift, the plumb bob will fall outside of the supportive area.

Digression Supportive Area
If a person can only stand with the use of aids such as a railing, there is no stable balance.

Digression Supportive Area
If the toe spring in the orthosis is taken into account, it is not the toes but the highest point of the rolling-off area that limits the supportive area at the front. At the back, the area is limited by the shoe sole.

In stance, the plumb bob should fall in the rear third of the front half of the supportive area. We refer to it as plumb bob reference area.

With both an AFO and a KAFO, the plumb bob should fall through the middle of the ap measurement into the plumb bob reference area. With a KAFO, the plumb bob should also fall through the area on the thigh shell where the greater trochanter is located. If the patient has extension limitations in the knee, have the plumb bob fall only from this location on the thigh shell when checking a KAFO on the workbench.

If the KAFO was produced without a dorsiflexion stop, ask another person to hold the orthosis at maximum knee extension before checking the plumb bob.

Note: in the case of an AFO without dorsiflexion stop, the orthosis’ alignment cannot be checked in this manner.

AFO: if the plumb bob is in front of the plumb bob reference area, correct the angle between the lower leg and the ground.

Note: you will find information on the adjustment options of the system joints in the instructions for use.

KAFO: if the plumb bob is too far in front of the plumb bob reference area and the thigh shell is vertical (A), check the extension limitation of the knee. If the extension limitation and the mechanical joint angle match, correct the angle between the lower leg and the ground.

If the thigh shell is not vertical (B), correct the angle between the lower leg and the ground. Check the result.

AFO: if the plumb bob is behind the plumb bob reference area, correct the angle between the lower leg and the ground. Correct the angle between the lower leg and the ground in the case of a motion limitation in dorsiflexion without changing the angle between the lower leg and the foot.

KAFO: if the plumb bob falls through the middle of the ap measurement (A) into the plumb bob reference area as intended (A), but the plumb bob through the greater trochanter (B) falls behind it, check the extension limitation of the knee. If the extension limitation and the mechanical joint angle match, correct the angle between the lower leg and the ground.

If the extension limitation of the knee and the mechanical joint angle do not match, make adjustments and then check the result. If the greater trochanter is still too far in the back, correct the angle between the lower leg and the ground.

If the plumb bob falls neither from the ap measurement (A) nor the greater trochanter (B) into the plumb bob reference area, correct the angle between the lower leg and the ground. Correct the angle between the lower leg and the ground in the case of a motion limitation in dorsiflexion without changing the angle between the lower leg and the foot.

A stable balance exists when the plumb bob falls in the plumb bob reference area, meaning the rear third of the front half of the supportive area. If this can only be achieved through compensation mechanisms on the part of the patient, check and correct the orthosis’ alignment.

If the plumb bob falls outside the supportive area, the patient cannot use the forefoot lever. Check and correct the orthosis’ alignment. In the case of system joints with spring units, check the spring force as well.

The joint angles in stance should correspond approximately to the physiological joint angles in mid stance. This enables a gait that is as physiological as possible.

Check the position of the plumb bob in the frontal plane to avoid lateral compensation movements. If the foot piece is in supination, this results in a rolling gait.

The patient should be able to put weight on both legs. If this is not the case, identify the cause (e.g. pain).

The levers should be as long as possible. The longer the levers are, the less strength the patient needs to achieve a stable balance.

Produce the orthosis shells so that they optimally support the muscle function. Orthosis shells should generally be as large as necessary and as small as possible. They should fit closely to bony structures without squeezing. On soft structures such as fatty tissue, muscles or tendons, they should only frame the tissue and be constructed in a flexible manner (see yellow area). This prevents pressure points and the squeezing of tissue, which is not only unaesthetic, but can also cause congestion and pain.

In stance, the patient’s shin should lean against the anterior tibial shell. If this is not the case, determine the cause (lack of confidence in the orthosis, missing dorsiflexion stop, insufficient anterior spring unit).

Construct the orthosis in such a way that all functional areas are covered through the alignment of the orthosis and the orthosis shells. This provides an optimal pressure distribution. The hook and loop fasteners are only used to secure the orthosis shells to the leg and should not exert any additional pressure.

Once you have completed the static check, continue with the dynamic check.