Neutral Zero Method: Treatment, Effect & Risks

With the neutral-zero method, the orthopedist evaluates and documents the range of motion of a joint using a three-digit code that is indexically valid and can be traced to the insurance system. In the neutral-zero method, the patient first stands in the neutral position of all joints and, from this neutral position, finally moves the joints individually away from and toward the body when asked to do so, with the range of motion indicated in the form of an angle about the respective axis of motion. Above all, expert opinions within the framework of statutory accident insurance, private insurance or a social court expert opinion can be made using the neutral-zero method, but the method is also relevant in the purely clinical field and is used here in particular for the assessment of disease- or accident-related limitations in everyday life.

What is the neutral-zero method?

The orthopedist uses the neutral-zero method to evaluate and document the range of motion of a joint. The neutral-zero method is an index used by orthopedics to evaluate and document joint mobility. The index is recorded in the form of a three-digit code. This code indicates the maximum range of motion of the joint as an angular degree about a specific axis. The neutral zero position of the joint marks the initial position. It is equivalent to an angle of zero degrees as it exists in the joints when standing upright with legs parallel, arms hanging relaxed, and thumbs pointing forward. From this neutral position, mobility is determined in the neural zero method by deflections in various directions. The first number of the code usually corresponds to a movement away from the body, the second number is 0 for the neutral zero position and the third number describes a movement towards the body. In individual cases, however, the extent of movement can also be specified according to the opposite order. For joints with multiple axes of motion, the orthopedist records a separate code for each axis. Since the code is standardized, the range of motion of a joint can be unambiguously illustrated in reports and letters. In this way, the severity of a movement restriction can be made comprehensible regardless of the institution.

Function, effect, and goals

The neutral-zero method is particularly important in connection with an expert opinion. Such an opinion may be required, for example, in the context of statutory accident insurance. Private accident insurance companies and social court expert opinions also work with the measurement sheets of the statutory accident insurance. These measurement sheets record the results of the neutral-zero method on the upper and lower extremities. However, the documentation and assessment procedure also plays a role on a purely clinical level, as the index can be used to determine the extent of movement restriction in everyday life due to illness or accident. The success of ongoing movement therapy can also be tracked under certain circumstances using the neutral-zero method. To do this, an initial assessment of movement ability takes place prior to therapy, which is then compared with the new data following the completion of therapy. To apply the neutral-zero method, the physician first has the patient standing upright with arms hanging relaxed, legs parallel to each other and thumbs pointing forward assume the neutral-zero position of all joints. He then asks the patient to extend, flex, internally rotate, externally rotate, abduct or lead the respective extremity or the relevant joints. Under certain circumstances, he or she may also actively guide the patient through the desired movement with assistance. Finally, reference angle values exist for writing down the mobility of each joint. For the shoulder joint, for example, the reference index for abduction and adduction corresponds to the code 180-0-20 to 40. If, however, the shoulder joint is impaired in abduction, for example, and can thus only be moved from the vertical upright position to the horizontal position, the physician records a restricted range of motion of 90 degrees instead of an unrestricted range of motion of 180 degrees. The index would then correspond to 90-0-20 to 40. The angular signs are not usually recorded in the index of the neutral zero method, as they are self-explanatory.

Risks, side effects and dangers

The neutral-zero method does not involve any risks or side effects for the patient. Therefore, it can be performed on an outpatient basis without any problems. Special features arise in the procedure mainly when the neutral-zero position of the joint cannot be achieved due to damage. In this case, the zero is not in the middle of the index, but moves to the side where there is a deficit in the range of motion. The angle number then indicates the deficit, with the 0 illustrating the range of motion itself. The neutral zero method cannot be used for statistical evaluations. For this purpose, one rather extracts the angular data for the individual movements from the index, adds them up and calculates an average of the general extent of movement. In most countries, the neutral-zero method does not exist per se and the extent of movement is always given by an average of the individual angles. In Germany, the neutral-zero method takes a special position in the context of spasticity. During fast movements, a spastic muscle contracts significantly earlier and thus reduces the extent of movement in everyday life. Therefore, in this clinical picture, during the method, the physician distinguishes between the extent of movement during passive slow movement and passive fast movement to correspond to the extent of spastic restricted movement.