Hand extensor tendon injury

　　This disease is mainly caused by traumatic factors, among which incising injuries are more common, often accompanied by finger nerve injury or fracture. Common causes include the stimulation of sharp objects, causing individual tendon injury, which is usually a complete or partial rupture of the tendon, resulting in the disappearance or decrease of tendinous tension, unable to pull the muscle to form contraction, so the affected limb is usually unable to move and clench a fist. Other causes such as blunt injury, mainly manifested as tendinous swelling, also accompanied by dysfunction.

　　Hand extensor tendon injuries are common hand injuries. Improper treatment often leads to complications such as edema, tenosynovitis, and tendon rupture, causing serious impairment of finger function. At the same time, due to the injury of tendons, the muscle contraction coupling can occur abnormally, and the muscle cannot contract normally, so complications such as limited arm movement and weakness may occur. If the injury is traumatic, it can become tenosynovitis, aggravating the condition.

　　The extensor tendons of the hand can also be divided into 5 areas.

　　1. Area I: From the terminal tendon insertion to the central tendon insertion.

　　2. Area II: Central tendon insertion to the middle of the proximal phalanx (distal end of the extensor tendon expansion).

　　3. Area III: Extensor tendon expansion to the distal edge of the wrist back ligament.

　　4. Area IV: Wrist back ligament area.

　　5. Area V: Forearm.

　　Hand tendon injuries caused by sending text messages are mainly due to the inflammation and thickening of the sheath surrounding the first group of extensor tendons on the back of the hand due to overuse and other reasons, resulting in pain when the thumb extends.

　　Long-term typing can lead to carpal tunnel syndrome, which refers to the symptoms caused by the compression of the median nerve as it enters the palm canal. It mainly leads to pain, numbness, and weakness in the thumb and index finger muscles.

　　Preventive measures:

　　1. When sending text messages, try to hold the phone with both hands to send it, to evenly distribute the pressure on both hands.

　　2. Create a good working environment, including adjusting the chair to a comfortable height, having enough space to stretch both feet while sitting, placing the computer keyboard directly in front of you when typing, and adjusting the height of the keyboard to a comfortable position for typing.

　　3. In necessary cases, appropriate painkillers and drugs to relax tense muscles should be administered. The patient must also follow the instructions of the occupational therapist, adjust the posture for typing and sending messages, and perform stretching exercises to minimize the opportunity for damage to the hand tendons.

      In addition to clinical manifestations, relevant auxiliary examinations are also essential for the diagnosis of hand extensor tendon injury. X-ray examination often shows no positive findings. You can continue to twist electromyography to rule out nerve injury.

　　What kind of food is good for the body for hand extensor tendon injury: should be light in taste, and rationally matched in diet.

　　First, treatment

      1. Repair of fresh extensor tendons: The extensor tendons except for the IV area have bone fibrous tubes and synovial sheaths, and other parts are wrapped by peritendinous tissue without sheaths. Therefore, only end-to-end suture is required. If the injury is in the part of the dorsal fascia of the finger, in addition to the central tendon and lateral tendon that need to be sutured, the fascia is repaired and fixed in the position of extension and extension of the wrist with palmar plaster splint after the fascia repair, and the postoperative adhesion problem is not as serious as that of the flexor tendons.

　　2. Treatment methods for extensor tendon injury: Due to the thin and elastic skin on the back of the hand, there is a layer of loose connective tissue between the extensor tendons and the skin, and the extensor tendons have no sheath and peritendinous tissue, except for the extensor retinaculum. Therefore, primary repair should be performed as long as the local conditions permit, which yields good results. There are many late repair methods for extensor tendon injury in the finger, and some of them are not satisfactory. Therefore, the importance of primary repair should be emphasized even more.

　　(1) Treatment of hammer toe: For hammer toe deformity caused by fresh closed tendon rupture, the injured finger should be immediately immobilized in a splint with the proximal interphalangeal joint flexed and the distal interphalangeal joint hyperextended for 5 to 6 weeks; for those with avulsion fractures of the distal phalanx on the dorsal side, use Bunnell wire pull-out suture technique to fix the avulsed bone fragments: namely, use a dorsal 'S' or 'Y' shaped incision at the distal interphalangeal joint, expose the extensor tendons with avulsed bone fragments, and use Kirschner wires to pass through the distal phalanx to its palmar side under the condition of bone fragment reduction, then pass a pull-out wire from the dorsal side to the palmar side, tie a knot with a pad on the button, leave the pull-out wire exposed, and close the wound. And use a splint to fix the proximal interphalangeal joint flexed and the distal interphalangeal joint hyperextended. For old tendinous rupture injury, tendinous repair surgery can be performed: use a dorsal 'S' or 'Y' shaped incision at the distal interphalangeal joint, expose the distal insertion of the extensor tendons that have been connected by scar tissue, cut it at the proximal insertion, and slightly free it towards the proximal side along with the scar tissue, do not remove the scar, otherwise it will be impossible to suture due to tendinous defect; overlap the two ends in the straight position of the finger distal phalanx; a Kirschner wire can be temporarily used to fix the distal interphalangeal joint in hyperextension and the proximal interphalangeal joint flexed 100°, or use a splint to fix at the above position. For long course of disease, physical laborers with obvious pain, distant interphalangeal joint fixation surgery can be performed. Regarding the position of distal interphalangeal joint fixation, if considering the functional position of finger flexion, it should be fixed at 15° to 20° flexion; if considering the aesthetic aspect of the hand, it should be fixed in a straight position.

　　(2) Central tendon bundle injury: Fresh injuries should be directly sutured in one stage as long as the local conditions permit, which is simple and has good effects. For chronic injuries, if the lateral tendon bundle is normal, repair can be performed using the lateral tendon bundle: Make an arched incision on the dorsal side of the finger, centered on the proximal interphalangeal joint, to expose the extensor structure of the finger back, and it can be found that the injured central tendon bundle has been connected by scar tissue; examine both sides of the tendon bundles, if the lateral tendon bundles are intact, they can be freed on both sides and brought closer to the dorsal side of the proximal interphalangeal joint; in the extended position of the proximal interphalangeal joint, suture the two lateral tendon bundles together on the dorsal side, fix with two sutures, or cut the distal ends of the lateral tendon bundles at the proximal end of the proximal interphalangeal joint and cross them on the dorsal side of the proximal interphalangeal joint. If the lateral tendon bundles are also injured, the tendon transfer repair can be used.

　　(3) Extensor tendon sheath injury: Fresh injuries can be directly sutured; if the injury is not long and the tissue of the sheath is still intact, direct suture can still be performed. For chronic injuries that cannot be directly sutured, extensor finger tendon flap repair, extensor tendon sheath self-repair, or combined tendon repair methods can be used for repair. After surgery, fix the metacarpophalangeal joint in an extended position for 3 weeks.

　　3. Fresh injuries of the extensor tendons of the hand, wrist, and forearm should be repaired as early as possible in one stage; for injuries with short duration and no tendon defects, direct suture can still be performed in the second stage; if the injury time is long after the injury or there are defects in the tendons and cannot be directly sutured, tendons can be transplanted or transferred to repair. The extensor tendons of the wrist are located within the tenosynovial sheath. When repairing the tendons in this area, to avoid adhesion of the repaired tendons, it is best not to place the sutured part within the sheath or to open the sheath.

　　(1) Extensor pollicis longus tendon injury: Fresh injuries have good primary repair effects. In late stages, if the tendons retract and cannot be directly sutured, the extensor digiti minimi tendon transfer repair can be performed. The method is: Make a small transverse incision on the dorsal side of the metacarpophalangeal joint of the index finger, find the extensor digiti minimi tendon on the ulnar side and deep surface of the extensor tendons of the index finger, and cut it at its insertion point, and suture the distal end to the extensor tendons of the index finger. Make a small transverse incision on the radial side of the wrist back, and pull out the cut extensor digiti minimi tendon from this incision. Make an arched incision near the site of the extensor pollicis longus tendon injury, isolate the distal end of the extensor pollicis longus tendon, and make a subcutaneous tunnel between this incision and the wrist incision, pull out the extensor digiti minimi tendon through the subcutaneous tunnel from this incision. In the position of wrist extension, thumb abduction, and straightening of the metacarpophalangeal and interphalangeal joints, suture the proximal end of the extensor digiti minimi tendon with the distal end of the extensor pollicis longus tendon in an interwoven manner. After surgery, use a plaster splint to fix the thumb abduction, metacarpophalangeal, and interphalangeal joint extension positions for 3 weeks.

　　Firstly, check the presence of the固有extensor muscle tendon of the index finger before the operation. That is, when the affected hand is clenched, the index finger is extended alone, and if it can be extended strongly, it indicates its presence. A transverse incision is made on the dorsal side of the metacarpophalangeal joint of the index finger, where two extensor tendons are visible, with the radial side being the total extensor tendon and the deeper one on the ulnar side being the固有extensor muscle tendon of the index finger. It is then freed and cut. Through the subcutaneous near the incision, it is turned at the 4th area exit and runs parallel to the extensor pollicis longus tendon, sutured to the distal end of the extensor pollicis longus tendon under appropriate tension.

　　(2) Repair of total extensor tendon defect: Early treatment of soft tissue extensor tendon defects on the dorsum of the hand caused by irregular contaminated injuries often involves initial wound coverage, with the tendon defect left for secondary treatment. The most ideal method is the free transfer of a dorsum pedis skin flap with the extensor digitorum longus tendon, which has the best effect, but requires solid fundamental skills in microsurgery. If a pedicle flap is used to cover the wound early on, free tendon transplantation can be performed. In certain injuries, such as those caused by combing machines with long defects and multiple extensor tendon defects, the plantar or palmaris longus tendons can be used as grafts, with the transfer of the ulnar flexor carpi ulnaris as the dynamo muscle, the proximal end sutured into the ulnar flexor carpi ulnaris tendon, and the distal ends sutured into the extensor tendons of the four fingers. The strength required to extend the fingers does not need to be too strong; in the III or V areas, sometimes the distal ends of the defect tendons are sutured into the healthy extensor tendons of adjacent fingers, with 1 to 2, or even 1 to 3.

　　II. Prognosis

　　The general prognosis is good.