TENDON INJURY
Injuries affecting the upper extremity and in particular the hands come to expect, as described in some studies, one third of workplace injuries.
The hands are critical to carrying out daily activities, from the rudimentary to the most technical and sophisticated. Most crafts require the use of potentially dangerous machinery. In connection with his hands, the highest risks of these activities are determined by avulsion-shears, and injured amputees subsection-bruised, crushed and cut with small objects. The injured were mainly young men (mean age 33 years), in relation to falls, cuts and shock. When considering treatment and possible consequences of a hand it is fundamental production mechanism and location of lesions. Among the occupational accident injuries increasingly become more important than those caused by traffic accidents.
The hand has three main functions:
The smart clip and grip, dependent on the median nerve and ulnar nerve gripping. Always maintain the function of 1st and 2nd fingers, with the 4 Th and 5 Th expendable.The tendon is poorly vascularized structure, composed 30% of collagen and elastin 2%, and infused in an extracellular matrix with 60% water. Collagen is synthesized by fibroblasts and constitutes 70% of dry weight of the tendon, and its breaking point closer to the steel and provides the tensile strength.The structural unit of collagen is the tropocollagen, consisting mainly of collagen type I, chains rich in glycine, proline and two amino acids, hydroxyproline and hydroxylysine, which increase its resistance. The orientation of the fibers takes place in direction of the tensile forces experienced by the tendon.With a tendon in tension forces applied quickly and obliquely promote rupture. The maximum dynamic capacity of the tendon decreases with age, being highest around the third decade of life.The tendon wound healing is similar to the healing of soft tissue injuries in three phases:
- Inflammatory phase
- Fibroblastic proliferative phase
- Phase production of collagen or scar remodeling
Diagnosis:
The diagnosis of tendon injuries is mainly clinical. Section of both flexor tendons in a finger, produces a complete extension of this. The deep flexor injury leads to a loss of flexion of the distal interphalangeal joint. The injury only to the superficial flexor does not cause posture changes in the finger. When diagnosing a partial injury of a tendon is a decrease of force, with pain on mobilization against resistance, maintaining range of motion. The injury of all the flexor tendons at the wrist will cause a completely hand extension, supination of the wrist.
The extensor tendons occupy a surface position on the dorsum of the hand, being less protected and more exposed to injury. Its diagnosis is simpler than that of the flexor tendons.
At the level of distal phalanx, the extensor tendon injury causes the hammer toe deformity, with inability to extend the distal interphalangeal. In proximal lesions impossibility of extension is easy to verify.
Treatment:
When it’s time to do the repair of the tendon, the anatomy of the various structures involved in the injuries of the hand, determines the procedure and results. The existence of a tendon tissue viable, adequate skin coverage, the conservation of circulation and sensitivity as well as reducing potential bone injury associated, are all necessary prerequisites for a successful repair of tendon function. Primary repair of all structures, regardless of the complexity of the injury, simplifies the procedure and improves outcomes. We understand that primary repair is carried out within 24 hours after injury; if performed subsequently, it is considered a delayed primary repair.
Complications:
The formation of adhesions (tenodesis) is the most common complication in the treatment of tendon injuries. Methods to prevent adhesions can be mechanical or biological.
- The mechanical types include postoperative mobilization protocols, conservation of the components of the pods and pulleys and a traumatic handling of the tendon and its sheath. Biological methods are an area under investigation.
- The release of these adhesions can be performed by surgery: tenolysis. Would be indicated when the range of motion does not improve within a period of time, despite correct treatment with splints and mobilization. There must be a minimum joint contracture with a nearly normal range of motion.
Other complications are rupture of the tendon or suture failure, usually in case of early withdrawal of immobilization or inadequate rehabilitation, but may also be related to the poor treatment compliance by patients (removal of the splint, heavy lifting …) According to several studies, in the case of the flexor tendons, the rupture rate between 4 and 5.7%.Joint contractures may be due to different causes: cutaneous fibrosis, tendon adhesions, fractures or vascular nervous injuries associated tears or scars of the volar plate or collateral ligament contractures. They may also be due to inadequate mobilization and use of dynamic flexion splint.The finger may occur after tendon repair of flexor tendons in relation to thickening in the area of repair.Hand in quadriga is the inability to achieve full flexion by the uninjured fingers of the hand. This complication is due to a shortening of the deep flexor tendon of the fingers on the injured finger, which affects the function of the same muscle in the rest of the fingers. The swan neck deformity, which is a hyperextension of the proximal interphalangeal joint associated with bending of the distal interphalangeal joint, is a rare complication. This in connection with isolated rupture of the common flexor and superficial lesions of the volar plate.In the case of flexor tendons, breakage of the pulley causes a tendon guitar string. A2 and A4 pulleys, located on the proximal phalanx and a half respectively, play a key role in mobility and strength of the fingers. The rupture of a pulley causes a large change in the efficiency of the route, strength and mobility of the tendons.The paradoxical extension of the interphalangeal joints of the injured finger while trying to forced flexion or lumbrical plus deformity, is related to a function ineffective or avulsion of the flexor digitorum profundus.Among the complications that can occur in the treatment of tendon injuries is the Reflex Sympathetic Dystrophy, which may appear in connection with any trauma or surgery of the hand.