Contracture(redirected from myostatic contracture)
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in physiology, prolonged, persistent, often irreversible contraction (rigidity) of the muscle fiber or of a section of it.
The cause of contracture is usually disruption of the processes of reconstitution (resynthesis) of adenosine triphosphoric acid (ATP). Contracture may be produced experimentally by many agents (electric current, change in the temperature or reaction of the medium, and certain biologically active or pharmacological substances, such as acetylcholine, veratrine, caffeine, and nicotine). In contrast to an ordinary muscle contraction, which extends in a wavelike manner along the muscle fiber, contracture is a prolonged, nonspreading contraction. During contracture the muscle develops tension and can perform mechanical work; heat production is increased in the area of contracture. The Russian physiologist N. E. Vvedenskii regarded contracture as a nonfluctuating stimulation of the muscle fiber.
In medical science, contracture is the limitation of mobility in a joint as a result of a pathological change in the joint surfaces or in the soft tissues that are functionally connected with the joint. One may distinguish flexor, extensor, abductor, adductor, and other contractures according to their predominant position; according to origin, a distinction is made between congenital and acquired contractures. At the root of congenital contracture is underdevelopment of the muscles and joints (torticollis, arthrogryposis, clubfoot, and so on) and of skin coverings (the cutaneous membranes between digits).
Acquired contractures may be dermatogenic (from Greek dermas, “skin”), which arise during healing, by means of the second intention of large defects in the skin after burns, wounds, inflammations, and so forth; desmogenic (from Greek desmos, “ligament”), which develop during corrugation of the fascies (connective-tissue membranes that surround the muscles), ligaments, and bursas after injury to them or inflammatory processes in them; myogenic (from Latin mys, myos, “muscle”), which are caused by traumas, acute and chronic inflammations of the muscles, and certain other pathological processes in the muscles; tendogenic (from Late Latin tendo, “tendon”), which arise as a result of injury or inflammation of the tendons and their sheaths; arthrogenic (from Greek arthron, “joint”), which are due to a pathological process in the joint—the disruption of the integrity of the joint surfaces or changes in the ligamentous apparatus; and neurogenic, which arise during illnesses of the central and peripheral nervous system.
Among these a distinction is made between reflex, spastic, and paralytic contractures. Reflex contractures develop during severe pain, prolonged protective tonic tension of the muscles (for example, flexor contracture of the hip joint with retroperitoneal abscesses). Reflex contracture gradually becomes myogenic as a result of changes that occur in the muscles. Spastic contractures arise as a result of irritation of the motor areas of the cerebral cortex and with affection of the central motor neuron, vascular diseases of the brain, inflammatory processes, traumas, and so forth. Paralytic contractures are often observed with poliomyelitis and are accompanied by loosening of the joints. Contractures caused by disruption of autonomic innervation develop after removal or irritation of a sympathetic trunk with a subsequent change in muscle tonus. The course of contracture is directly dependent on the degree of affection of the joint, the localization, and the cause of the contracture.
Prophylactic measures include timely splinting of the extremities and treatment of the primary cause. Treatment consists of the correction of the contracture by traction or on distraction apparatus, the use of plaster casts applied in stages, therapeutic exercise, massage, and physiotherapy. With persistent contractures that do not yield to conservative measures surgery is performed.
V. L. ANDRIANOV, L. O. BADALIAN, AND N. N. NEFED’EVA