DIAGNOSTIC-CORRECTIONAL COMPLEX OF KINEMATICS OF THE RADIUS JOINT

Pronation-supination is a circular movement of the forearm in relation to the longitudinal axis. It involves two mechanically interconnected joints:
• superior radioulnar (SRU), which anatomically belongs to the elbow joint;
• Inferior radioulnar (IRU), which is not anatomically included in the wrist joint.

The function of supination is provided by the following muscles:
1) a short arch support, twisted around the neck of the beam and realizing the effect of “untwisting”;
2) the biceps of the shoulder, attached to the top of the “supination geniculate bend”, i.e. to the tuberosity of the radius, which carries out traction and achieves maximum efficiency with the elbow joint bent at an angle of 90 °.

The function of pronation is provided by the following muscles:
1) a square pronator, twisted around the distal end of the ulna, when it is “untwisted”, the radius moves around the ulna;
2) a round pronator attached to the top of the “pronation geniculate bend” of the radius and acting through traction.
Pronators are innervated by only one nerve – the median (n. medianus, CV – CVIII and TI), and the arch supports – by two nerves: radial ((n. radialis, CV – CVIII) and musculocutaneous (n. musculocutaneus, CV – CVII) ( the latter innervates the biceps brachii).

The articular complex of the wrist joint consists of two joints:
• radiocarpal, formed by the distal end of the radius and the proximal row of the carpal bones;
• midcarpal between the proximal and distal rows of carpal bones.
Movements in the wrist joint occur around two axes when the hand is in the anatomical position, i.e. in a position of complete supination.
The transverse axis lies in the frontal plane T and controls the movements of flexion and extension carried out in the sagittal plane:

flexion – the anterior (palmar) surface of the hand moves towards the anterior surface of the forearm;

extension – the posterior (dorsal) surface of the hand moves towards the posterior surface of the forearm.
The anteroposterior axis lies in the sagittal plane S and controls the movements of adduction and abduction that occur in the frontal plane:

adduction or ulnar deviation – movement of the hand towards the longitudinal axis of the body, its inner (ulnar) edge forms an obtuse angle with the inner edge of the forearm;

abduction or radial deviation – movement of the hand from the longitudinal axis of the body, its outer (radial) edge forms an obtuse angle with the outer edge of the forearm.

Flexion (FLEX) requires activation of muscles I (flexor carpi ulnaris, innervation – n. ulnaris (CVII-CVIII)) and III (radial flexor of the wrist, innervation – n. medianus (CVI-CVII) and long palmar muscle, innervation – n. medianus (CVII—CVIII)) groups.
Extension (EXT) requires the participation of muscles II (ulnar extensor of the wrist, innervation – n. radialis (CVI-CVIII)) and IV (long, innervation – n. radialis (CV-CVII) and short extensors of the wrist, innervation – n. radialis ( CV-CVII)) groups.
• Adduction (ADD) is carried out by muscles I (ulnar flexor of the wrist, innervation – n. ulnaris (CVII-CVIII)) and II (ulnar extensor of the wrist, innervation – n. radialis (CVI-CVIII)) groups.
Abduction (ABD) is carried out by muscles III (radial flexor of the wrist, innervation – n. medianus (CVI-CVII) and long palmar muscle, innervation – n. medianus (CVII-CVIII)) and IV (long, innervation – n. radialis (CV —CVII) and short radial extensors of the wrist, innervation – n. radialis (CV—CVII)) groups.
When measuring and analyzing these movements, as a rule, a virtual coordinate system is considered (Fig. 1).

In this coordinate system, the X-axis, which runs along the geometric axis of the forearm, defines the so-called neutral line, and the XOY plane defines the zero plane.

For the diagnosis and corrective implementation of the presented movements for therapeutic and rehabilitation purposes, a Diagnostic and Correction Complex of the Kinematics of the Wrist Joint (D3KLS) was developed, consisting of a lodgment LI, three specialized modules MII (MII-1, MII-2, MII-3), a module-propulsor MD and connecting elements III (Fig. 2).

The lodgement is a device designed to fix the patient’s hand and orient its neutral axis with the axis of the module involved, which, in fact, determines the amount of the required movement (for D3KWJ – deviation of the angular movement). The lodgement consists of a base 1, three posts 2 and three supporting half-rings 3 (in some cases with a latch 4) covered with a porous soft material 5 for comfort (Fig. 3).

The flexibility of setting the lodgement depending on the size of the patient’s limb is implemented by the possibility of independent movement of the racks 2 along the base and independent movement of the rings 3 relative to the base in height. This allows you to implement a reliable fixation of the forearm of the hand, realizing the support according to the scheme of the classical support of a cylindrical body at three points. The semi-ring with lock 4 is used when performing pronation-supination movements to prevent “parasitic” movements.

The pronation-supination module (MII-1) is designed to implement the required deviation in the range from -80⁰ (pronation) to 80⁰ (supination) from the zero position determined by the XOY plane (see Fig. 2, d). The module consists of a base 1, two posts 2, a shaft 3, on which a measuring disk 4 is fixed with a mount for the measuring instrument 5, and two handles: the patient’s handle 6 and the operator’s handle 7. Depending on the accepted rehabilitation technique, the module can be equipped with a clutch module 8 (Fig. 4).

By means of connecting elements III, the module is combined with the LI lodgement into a rigid structure that determines the coaxiality of the neutral line of the patient’s hand and the axis of the module.

The abduction-adduction module (MII-3) is designed to implement the required deviation in the range from -70⁰ (abduction) to 70⁰ (adduction) from the zero position determined by the XOY plane (see Fig. 2). The module consists of two bases 1, three posts 2, a shaft 3, on which a measuring disk 4 is fixed with a mount for the measuring instrument 5, and two handles: the patient’s handle 6 and the operator’s handle 7 (Fig. 5).

Depending on the adopted rehabilitation methodology, the module can be equipped with a clutch module 8
By means of connecting elements III, the module is combined with the LI lodgement into a rigid structure that determines the coaxiality of the neutral line of the patient’s hand and the axis of the module.

The flexion-extension module (MII-3) is designed to implement the required deviation in the range from -70⁰ (flexion to 80⁰ (extension) from the zero position determined by the XOY plane (see Fig. 1, c). The module consists of two bases 1, three racks 2, shaft 3, on which a measuring disk 4 is fixed with a mount for the meter 5 and two handles: the patient’s handle 6 and the operator’s handle 7.

Depending on the adopted rehabilitation methodology, the module can be equipped with a friction clutch module 8 (Fig. 6).
By means of connecting elements III, the module is combined with the LI lodgement into a rigid structure that determines the coaxiality of the neutral line of the patient’s hand and the axis of the module.

In order to automate the monotonous cyclic movements of the operator, with long cycles of rehabilitation procedures, any of the above modules provides for the use of the MD propulsion module (Fig. 7). The module is installed in place of the operator’s handle using a sleeve coupling 1, and its orientation with respect to the modules used is made by means of connecting elements III.

The software used in the MD propulsion module allows you to set the value of the minimum and maximum angle of deviation, determine the number of exercises in a single cycle and set the required number of exercise cycles. It is also possible to adjust the angular rate of rotation within the deviation angle.