Abduction / Adduction

Lying position (side):

The most stabilised position for testing abduction but it limits adduction to the neutral position. Best for abduction research poor for adduction.

To view a set up video press here 

Lying position (supine):

This position requires a dynomometer with allot of height adjustment (Kin-Com) it can be difficult to stabilise correctly.

Standing position:

In the standing position (see below) stabilization is difficult if not impossible (and probably undesirable). Testing in this position is more functional than that in the seated position and allows the investigation of adduction. It is claimed that this is more functional and involves the use of gravity. However, this position is difficult to stabilize. If the knee is allowed to flex the resulting gravitational moment of the leg is lower than if the knee was fully extended and rectus femoris contraction may result in variations of the strength curve. However, flexion of the knee is recommended, although only passively against gravity if for no other reason than to avoid sciatic nerve traction. Best for athletes.

To view a set up video press here 

Stabilisation:

Lying: In the lying position stabilisation normally only involves a pelvic strap to prevent the torso from influencing the results and a leg strap for the opposite (non tested) leg.

Standing: Stabilistion in the standing position is not normally required as this is the most functional position.

Attachments:

Lying (side) and Standing: The thigh stabiliser pad is normally used and should be positioned just proximal to the knee joint.

Supine: The pad should be placed just above the foot to hold the weight of the limb. A dual pad can be obtained as described by Donatelli et al. (1991) however this is not necessary. (The knee must be kept straight during the test.)

 Axis of rotation:

The instantaneous axis of rotation place the actuator axes opposite the hip joint 1 cm medially to the anterior superior iliac spine (red line seen above).

Anatomical zero:

With leg straight (as in standing).

Range of motion:

The accepted ROM for abduction is 45 degrees whereas for adduction it may be up to 25 degrees (Miller, 1985). Obviously movements into adduction are usually prevented by a mechanical block (the other leg).

Gravity correction:

As the lever arm can be very long and heavy in these movements setting of gravity correction is essential.

Speeds:

Donatelli et al. (1991) suggest velocities between 30-90 degrees/second, however, 30 degrees/second is probably the most functional and practical.

Generally it is accepted that speeds of 30 degrees/second and multiples of this should be used.

Protocols:

Interpretation:

In the hip it is normal to look at the ratio between the right and left sides there should be a 0-10% difference between the sides. Anything beyond this would indicate a muscle imbalance which would be best corrected.

Eccentric results are generally 30% higher than concentric within the same muscle.

Concentric/concentric ratio; abduction/adduction 0.40% this means the abductors are only 40% of the adductors or the other way around is the adductors are 60% stronger than the abductors.

Normative values: