Finger flexor tendon injury

　　1. Etiology

　　It is mostly caused by incision and piercing injuries.

　　2. Pathogenesis

　　After the external rupture of the tendon, due to the contraction of the muscle, the proximal end retracts and can even retract a long distance, such as when cut at the proximal phalanx, the distal end can retract to the palm. When the finger is injured, the finger often presents a flexed grasp, and after the joint is extended, the distal end moves forward again. It is difficult to find both ends during surgery, and the repair is also difficult. After suturing, due to tension, the sutures may separate and form a gap, affecting healing.

　　There has been a long-standing debate on whether the tendon can heal on its own after being cut, as it cannot be seen that there is a bleeding blood vessel inside the tendon. The theory of exogenous healing dominated for a long period of time, which believed that the tendon lacks its own healing ability and needs to be repaired by the surrounding tissue rich in blood supply, so that it can be repaired. Especially in the sheath area, the sheath affects the growth of granulation tissue, and part of it must be removed to allow the tendon to heal. Scar formation leads to tendon adhesion and affects the sliding function of the tendon, which is an unavoidable consequence after tenolysis. Therefore, in the sheath part, especially in the II area, the initial treatment is limited to repairing the surrounding skin and soft tissue, and late tendon transplantation is used to reconstruct the flexion function of the finger. If initial repair is to be done, it is limited to neat and non-contaminated incisions, where part of the tenoperiosteum is cut off, the proximal palmar flexor tendon is removed and sutured to reduce adhesion and preserve the functional movement. If both the deep and superficial palmar flexor tendons are repaired, they may become more adherent, causing more severe functional impairment, which is counterproductive.

　　The tendon is a common site of injury in the hand. Improper treatment often leads to complications such as edema, tendon adhesion, and tendon rupture, which can cause severe functional impairment of the fingers.

　　Edema usually appears within 48 hours after surgery and is a common and relatively mild complication after hand trauma.

　　It is difficult to avoid adhesion with surrounding tissues after tenolysis surgery. Once adhesion occurs, it may lightly affect the movement of the tendon or severely lead to the failure of the tenolysis surgery.

　　Tendon rupture: rupture of dense connective tissue.

　　Tendons are the transmission devices of joint movement and an important link for the normal function of the hand. Even if the function of each joint in the hand is normal, the function of the hand will be completely lost after the tendons are injured.

　　First, the division of flexor tendon regions:Due to the special anatomical structure of the flexor tendons at different locations, the principles and methods of treatment are not the same. According to the Verdan classification, they can be divided into 5 regions.

　　1, I region:From the insertion point of the superficial flexor muscle of the middle phalanx to the insertion point of the deep flexor muscle of the distal phalanx, the thumb is from the middle of the proximal phalanx to the insertion point of the long flexor tendon of the thumb.

　　2, II region:The middle of the middle phalanx to the neck of the metacarpal, often referred to as the 'no man's land'.

　　3, III region:“Palm region”, that is, from the neck of the metacarpal to the distal margin of the transverse carpal ligament.

　　4, IV region:Carpal tunnel region.

　　5, V region:Antecubital region.

　　Secondly, the flexor tendons of the thumb are also divided into 5 regions:

　　1, I region:The insertion point of the long flexor tendon of the thumb.

　　2, II region:From the neck of the proximal phalanx to the neck of the metacarpal, that is, the sheath area.

　　3, III region:The masseter muscle area.

　　4, IV region:Carpal tunnel region.

　　5, V region:Antecubital region.

　　Most tendons in the hand are open, mostly caused by cutting injuries, often accompanied by nerve and vascular injuries or bone and joint injuries, and may also occur in closed tears. After the tendons are ruptured, the corresponding joints lose their function of movement. For example, when the superficial flexor tendon is ruptured, the proximal interphalangeal joint of the corresponding finger cannot be flexed; therefore, this disease is mainly caused by traumatic factors. Therefore, paying attention to production safety, doing a good job of occupational protection, and preventing wrist injuries are the key to the prevention and treatment of the disease.

　　X-ray examination did not show any positive findings.

　　Examination of tendon injury

　　Tendon rupture shows a change in the resting position of the hand. For example, when the flexor tendon is ruptured, the straightening angle of the finger increases, and when the extensor tendon is ruptured, the flexing angle of the finger increases. It also results in the loss of the active flexion or extension function of the finger, and may also appear some typical deformities, such as the rupture of the deep and superficial flexor tendons, the finger being in a straightened state. When the extensor tendon at the proximal aspect of the metacarpophalangeal joint is ruptured, the joint is in a flexed position. When the extensor tendon at the proximal aspect of the middle phalanx is injured, the proximal interphalangeal joint is in a flexed position, and when the extensor tendon at the distal aspect of the middle phalanx is injured, the distal phalanx of the finger is in a hammer-shaped deformity. It should be noted that when multiple tendons participate in the function of the same joint, the injury of one tendon may not show obvious functional impairment. For example, flexion and extension of the wrist.

　　The examination method for flexor tendons is to fix the middle phalanx of the injured finger, allowing the patient to actively flex the distal interphalangeal joint. If it cannot be flexed, it indicates a deep flexor tendon injury. Fix the other three fingers except the one being examined, and allow the patient to actively flex the proximal interphalangeal joint. If it cannot be flexed, it indicates a superficial flexor tendon rupture. When both the deep and superficial flexor tendons are ruptured, the interphalangeal joint of the finger cannot be flexed. To check the function of the long flexor tendon of the thumb, fix the proximal phalanx of the thumb, and allow the patient to actively flex the interphalangeal joint. The flexor digitorum brevis and interosseous muscles have the function of flexing the metacarpophalangeal joints of the fingers. The rupture of the flexor tendons does not affect the flexion of the metacarpophalangeal joints and should be noted.

　　1、What food is good for hand flexor tendon injury:Diet should be light and balanced, with a reasonable diet. Vegetarian diets should be well-constructed, and the three major nutrients needed by the human body - sugar, fat, and protein - are all very rich, meeting the reasonable needs of the human body.

　　2、What food should not be eaten for hand flexor tendon injury:Food to avoid, do not eat any citrus fruits, and pay attention to the diet of osteophytes, especially oranges and tangerines. Also avoid smoking and drinking.

　　First, treatment

　　1、Tendon suture method

　　(1) Requirements for tendon suture:

　　① The suture method for tendon suture should be simple, practical, have good tensile strength, and have little impact on the blood circulation of the tendon ends.

　　② Adhere to non-traumatic operation techniques, and the suture site should be smooth to avoid long-term exposure.

　　③ Select non-traumatic tendon suture threads with good tensile properties and little tissue reaction. Tendon suture should be performed with a round needle to reduce damage to the tendon.

　　(2) Tendon suture method:

　　① The one-end suture method for tendon ends is suitable for fresh tendon rupture suture, or suture of tendons with equal diameters.

　　A、Bunnell suture method: Sutured with double straight needles and polyester monofilament thread (3-0) as shown in the figure. This method is complex to operate and has an impact on the blood circulation of the tendon ends, and is now basically not used.

　　B、'8' shaped suture method: Sutured with a single needle monofilament (3-0) thread as shown in the figure. This method is simple to operate, but the tensile strength at the sutured site of the tendon is weak.

　　C、Retractable wire method: Select 36#～38# wire or 5-0 non-traumatic wire tendon suture. The near end of the tendon is sutured with an '8' shaped suture, and the wire is pulled out through the far end of the tendon and fixed to the skin surface with a button to reduce the tension at the junction of the tendon ends. After 4 weeks, the wire under the button is cut with scissors, and the wire is pulled out from the near end.

　　D、Kessler suture method: Sutured with double straight needles and polyester thread (5-0) as shown in the figure. This method has strong tensile strength and can be used for tendon sheath tendon suture, with controlled early passive activity with assistive devices.

　　Improved Kessler method: Based on the original method, an additional circle of intermittent suture is added around the tendon suture site to strengthen the local tensile strength and make the sutured area smooth and flat.

　　E、Kleinert suture method: Sutured with 3-0 non-traumatic straight needle monofilament thread, the suture method is simple, has strong tensile strength, and causes little interference with the blood circulation of the tendon ends. To make the sutured ends smooth and have better tensile strength, intermittent sutures are made around the edges.

　　F、Becker suture method: The tendon ends are trimmed into a bevel, and sutured with 5-0 non-traumatic monofilament thread. This method has strong tensile strength due to the large number of sutures, and the tendon ends need to overlap, affecting the length of the tendon. It is suitable for heterotopic tendon suture.

　　G、Intramuscular suture method: The ends of the tendon are sutured longitudinally with a single needle circular non-invasive suture, and the loops at the entry and exit points are fixed with an '8' shaped suture. Most of the sutures are embedded within the tendon.

　　H. Tsuge suture method: Using a straight needle suture (3-0 or 5-0), pass a needle horizontally about 1.0 cm from the tendon break, pull the needle out and then insert it into the loop. Tighten the suture to hold a little of the peritenon and tenon bundle. Then, insert the needle longitudinally into the tendon and pull the needle and thread out from the palmar side of the tendon break. Then, insert into the opposite end, enter the needle at the palmar side, and pull the needle out 1.0 cm from the break. Pull the suture thread to align the tendon ends, cut one thread, and pass a horizontal needle at the exit point, tie a knot with the cut thread end.

　　② Tendon end suture method on one side:

　　A. When a dynamic muscle tendon is transferred to multiple tendons, the weaving method should be used for suture.

　　B. Tendons with unequal diameters can also be sutured using the weaving method.

　　C. Tendons with equal diameters can also be sutured using the weaving method.

　　③ Fish mouth suture method: Used for the transplantation of tendons with different diameters.

　　④ Tendon-bone suture method: Applicable to the suture where the tendons insert into the bone.

　　There are various methods of tendon suture, each with its own advantages and disadvantages. Regardless of which method is used, it should be simple to operate, strong in tensile strength, minimally interfere with the blood circulation of the tendon ends, and the suture site should be smooth and flat. The specific application should be selected according to the specific situation.

　　2. Fresh flexor tendon repair:Although there are still different practices, the basic operation is to perform regular surgery during emergencies.

　　Wound debridement: To facilitate operation, an extended incision is required, with Z-shaped or continuous serrated incisions made at the finger and palm, and longitudinal Z-shaped incisions at the wrist and forearm. Deep tissues should be fully exposed to investigate the condition of various tissue injuries. In addition to the tendons and sheaths themselves, nerves and blood vessels must also be clearly identified and treated simultaneously. After the flexor tendon rupture, due to the extension of the finger joints, the distal end retracts, so the finger joints are generally flexed to the angle of injury, allowing the distal end to be exposed at the wound. The proximal end retraction is often greater. If the long tendinous loop is intact and continuous, the long tendinous loop can limit its retraction. If it is ruptured near the attachment point of the long tendinous loop, the proximal end can retract very far; in type II rupture, it can retract to the palm, and in type III rupture, it can retract into the carpal tunnel. First, the wrist and metacarpophalangeal joints should be passively flexed, and the flexor muscles of the forearm should be massaged to allow the ruptured tendons to slide forward to the site of rupture. To facilitate observation or surgical manipulation, the synovial sheath should be incised in the shape of an 'L', and the transverse ligament in the carpal tunnel can also be incised at one end. It is forbidden to use hemostats blindly in the sheath tube or palm passage, which may cause injury, resulting in extensive adhesions after surgery and seriously affecting function. After finding the distal ends, repairs should be made according to different regions.

　　Area Ⅰ: Refers to the rupture of the deep flexor or hallux longus flexor tendons near the short tendinous loop, which can be directly sutured using the Kessler method. If the retraction is far, the tendinous end can be sutured first with an '8' shape using a wire. The wire tail is pulled out from the distal palmar aspect of the nail, twisted and tied on a rubber pad to prevent retraction of the proximal tendons, and then the tendons are sutured end-to-end. It is also possible to split the distal flexor tendinous flap into two, inserting the proximal tenon head in between for a mattress suture; or to make a split in the phalanx at the insertion site of the deep flexor tendons, lift the bone flap, embed the tenon head into the bone fissure, and then suture the tendons.

　　Ⅱ Zone: The principle has changed, the forbidden zone has been broken, and primary repair is the most satisfactory treatment. The 'Z' shaped incision is used to expose the flexor tenosynovium, protecting the固有血管、nerve bundle of the finger, and if there is a nerve rupture, it is repaired together with the completion of the tendon suture.

　　Make an L-shaped incision near the wound end of the synovial sheath, try to cut the part of the synovial sheath that crosses the ligament while avoiding the annular ligament part, suture the triangular flap to pull it open with a牵引线, so that the internal structure of the sheath can be seen. Bend all the joints and press the muscle belly to make the distal ends of the two tendons slide out of the sheath opening separately, observe the injury condition and debridement. First, bring out the proximal flexor tendon, to prevent retraction, a needle can be used to cross the synovial sheath at 1.5 to 2 cm from the proximal end to hold it in place. The deep and superficial tendons should be kept together to prevent hindrance to the blood supply connection, a half Kessler suture or other suture method can be taken on the deep tendon first, and the thread head is pulled out from the distal end as a牵引 tool. The superficial tendon should be repaired according to the location of the break in the Camper crossing. If the break is beyond the crossing, the two tendons are sutured separately in an '8' shape; if the break is near the crossing, Kessler suture can be used, and it must be smooth on the surface. If the superficial tendon cannot be repaired, the proximal segment can be cut off; the distal end is preserved as the posterior tendinous bed for the deep tendon sliding. If the distal end of the superficial tendon is too short, it often causes hyperextension deformity at the proximal interphalangeal joint after surgery. After the repair of the superficial tendon is completed, repair the deep tendon, regardless of the suture method used, keep the depth at half on the palmar side, and bury the knot inside the tendon. The surface is sutured with 9-0 monofilament nylon thread in an interrupted manner to make it smooth. The synovial sheath is also sutured carefully, after removing the injection needle, flex the wrist 30°, then gently flex and extend each joint of the fingers, to see if the sutured tendons can pass through the repaired part of the sheath freely. Maintain the position of the wrist and fingers, do not let the suture pull the tendon apart. Repair the nerve and suture the skin, stick a shirt collar hook on the nail, and fix it with a Kleinert activity splint.

　　If the synovial sheath is broken and cannot be repaired, some people use autologous or heterologous biological materials or synthetic materials for repair, with varying reports on the effectiveness; or the damaged part of the synovial sheath can be excised. Generally, the A2 and A4 annular ligaments should be partially retained as much as possible to preserve their pulley function. If the injury is in the proximal part of the II Zone, the A1 pulley is removed, which does not interfere with the movement, as if it has been shifted forward in the III Zone.

　　Ⅲ Zone: The repair of tendons and the digital common nerve is easy and effective. The suture site is wrapped with the蚓状肌 to prevent adhesion.

　　Ⅳ Zone: Tendons are within the carpal tunnel, where a total of 9 tendons and the median nerve pass through. A Z-shaped incision is made on the skin, the transverse carpal ligament is cut from one end, the flexor digitorum profundus and flexor pollicis longus tendons are repaired, and a segment of the flexor digitorum superficialis tendon is resected from both the distal and proximal ends to prevent adhesion. If only the superficial layer of the flexor tendons is ruptured, the entire repair is performed, the median nerve is sutured, and the transverse carpal ligament does not need to be sutured back, thus avoiding the formation of a bowstring.

　　V area: From the origin of the tendons to the segment entering the carpal tunnel, there is peritenon tissue surrounding, and all breaks should be repaired. If the median or ulnar nerves are injured, they should be repaired as well. Postoperative controlled activities should be performed.

　　3. Tendon repair in all areas

　　(1) I area tendon repair: The flexor profundus digitorum in the I area is injured, and the distance of retraction will not be much due to the tenoception and lumbrical muscles at the proximal end of the rupture.

　　① Direct suture of the tendon ends or surgery to move the proximal end forward: If the proximal end of the flexor profundus digitorum has sufficient length and the distal end is longer than 1 cm, the ends can be directly sutured. If the distal end is shorter than 1 cm, the residual distal end can be excised, and the proximal end can be moved forward to reconstruct the insertion point. If the proximal end retracts too much and the deep muscle cannot pass through the bifurcation of the superficial flexor tendon, the insertion point of the superficial flexor tendon can also be moved forward and sutured to the distal end of the flexor profundus digitorum. After the tendon ends are moved forward, due to the high tension, the extension of the injured finger may be restricted in the early stage, which can be corrected after appropriate functional exercises.

　　② Tendon fixation: If the distal end of the flexor profundus digitorum is longer than 1 cm after the rupture in the I area, but the proximal end retracts too much and cannot be directly sutured, and the superficial flexor tendon function is good, tendon fixation can be performed. That is, the distal end is fixed on the middle phalanx, so that the distal interphalangeal joint is in a functional position, which is convenient for gripping objects stably.

　　③ Distal interphalangeal joint fusion: If the proximal end of the flexor profundus digitorum has shortened or has a defect, the superficial flexor tendon function is normal, the distal interphalangeal joint has poor passive movement, or the finger joint is also injured, interphalangeal joint fusion at the functional position can be performed. This method is reliable for restoring the pinching function of the injured finger.

　　(2) II area tendon repair: There is no need to repair the superficial flexor tendon in the II area, and the flexor profundus digitorum can compensate for most of the function. If the flexor profundus digitorum is injured and the superficial flexor tendon function is normal, distal interphalangeal joint fusion or tenodesis can be performed. If both the superficial and deep flexor tendons are ruptured, free tendon grafting or tenodesis should be performed to reconstruct the function of the flexor profundus digitorum.

　　(3) III area tendon repair: Tendon injuries have a short duration, and the proximal tendons retract to the palm or wrist. Direct suturing can be performed for both superficial and deep flexor tendons. If the injury is longer and the direct suturing of the superficial flexor tendon is not possible, no repair is required. When the flexor profundus digitorum or both superficial and deep flexor tendons are injured, free tendon grafting can be performed to reconstruct the function of the flexor profundus digitorum. When the superficial and deep flexor tendons are injured at different levels, the proximal longer tendons can be sutured to the distal end of the flexor profundus digitorum to restore its function.

　　(4) IV area tendon repair: There are many tendons in the carpal tunnel, and the main focus should be on repairing the flexor profundus digitorum and flexor pollicis longus tendons. When free tendon grafting is required, the sutured part of the tendons should be located between the III and V areas.

　　(5) V area tendon repair: Tendons with no defects can be directly sutured, and the superficial flexor, deep flexor, flexor pollicis longus, and flexor carpi radialis tendons should be repaired separately. When the tendons are not at the same level and cannot be directly sutured due to shortening or defects, the proximal longer tendons can be transferred to the distal end of the flexor profundus digitorum.

　　(6) Repair of the flexor pollicis longus tendon: When the flexor pollicis longus tendon is injured in any area, direct suture should be performed when the distal ends are not significantly shortened. If there is slight shortening of the tendon or muscle, it can be overcome by the flexion of the wrist joint, and the hand can recover to the normal sliding range through functional exercise after the operation. The suture points of the tendons should avoid the metacarpophalangeal joint and the wrist joint, otherwise adhesion is easy to occur. When there is a defect in the tendon, methods such as tendon extension, grafting, and transfer can be used for repair. When all the above methods cannot be implemented, interphalangeal joint tenosynovitis can be performed, or joint fusion surgery.

　　① Lengthening of the flexor tendon: The flexor pollicis longus tendon is a unipennate muscle, and the tendon on the lateral side of the muscle is longer, which can be extended by 'Z' letter extension to extend the tendon, so as to directly suture the ends or reconstruct the insertion point of the tendon.

　　② Transfer of the superficial flexor tendon of the ring finger: The superficial flexor tendon and the flexor pollicis longus are synergistic muscles. The superficial flexor tendon is cut from the proximal edge of the short tendon group, and the tendon is pulled out from the proximal end of the carpal ligament and transferred through the carpal tunnel to the flexor pollicis longus tendon.

　　4. Pulley reconstruction surgery:If the A2 and A4 pulleys are still present after the tenosynovial injury, the basic function of flexing the fingers can be guaranteed. If these two annular ligaments are destroyed, the flexor tendons will become弓弦状, greatly affecting the function of flexing the fingers, and if necessary, they can be reconstructed during the second-stage tendon repair.

　　The material for the reconstruction of the pulley can be the longitudinal split of half of the palmaris longus tendon or other tendons, and the soft tissue with the phalanx and extensor tendon is separated laterally until it can be around both sides. In hand surgery instruments, the pulley forceps have a large semi-circular arc-shaped hook on the clamp head, which is convenient for blunt tissue separation, wraps around the opposite side, pulls back the tendon, and the tendinous sheath is on one side facing the center, tightens and sutures, and the suture is turned above the extensor tendon on the back side.

　　5. Free tendon grafting:Free tendon grafting surgery is suitable for repairing tendon defects in various regions of the hand. However, it is more commonly used for repairing tendon defects within the finger sheath.

　　6. Donor tendons for free tendon grafting:The palmaris longus tendon, extensor digitorum longus tendon, tibialis posterior tendon, extensor indicis proprius tendon, and superficial flexor tendon of the finger can all be used as graft tendons. The palmaris longus tendon is flat and long, the longest can be cut into 15cm, which is the first choice for graft tendons. The extensor digitorum longus tendon is longer, flat, and has more tendinous intersections, often cut from the extensor tendons of the second to third toes. The tibialis posterior tendon is the longest tendon in the body, twice the length of the palmaris longus tendon, and the incidence rate of this muscle is 93%. Due to the difficulty in preoperative examination of the absence of this muscle, and its deep position, it is not easy to cut, and currently it is used less. The extensor indicis proprius tendon is rarely used as a free tendon graft, its tendon is shorter, usually can be cut 8cm. The superficial flexor tendon is thicker and larger, and it is easy to adhere after transplantation, so it is used less.

　　7. Adjustment of the graft tension:Over-tension of the tendon graft leads to limited extension of the fingers; insufficient tension results in incomplete flexion of the fingers. Proper adjustment of tendon tension is an important factor for achieving good function in tendon grafting. Adjust the tension of the tendon with reference to the rest position of the adjacent finger. The position of the affected finger after the tendon graft should be slightly more flexed than the rest position of the adjacent finger.

　　If the proximal end of the tendon is adherent near the original wound or the injury time is short, and there is no significant change in the muscle tension of the broken tendon, the degree of finger flexion of the transplanted tendon can be adjusted to be consistent with the adjacent finger at rest. If the injury time is long and the muscle has contracted, a greater muscle tension is felt when pulling the broken end, the tension of the tendon transplant should be appropriately relaxed, that is, the position of the injured finger is slightly extended compared to the adjacent finger at rest after the suture of the tendon, in order to prevent the finger from not being completely extended after surgery. When the muscle has atrophy due to disuse, the muscle tension is relaxed when pulling the tendon, and the tension of the transplanted tendon should be slightly tighter to prevent incomplete finger flexion after surgery and weak strength.

　　8, Staged flexor tendon surgery:For fingers with poor blood circulation, more scars, or those not suitable for primary free tendon transplant, staged tendon transplant surgery can be performed.

　　(1) First-stage surgery: Implant a silicone rubber strip substitute for the flexor tendon into the site prepared for the transplant. The distal end is fixed to the base of the distal phalanx, and the proximal end is placed in the tissue of the palm or forearm. After the wound heals, passive finger flexion and extension movements are performed. A false sheath is gradually formed around the silicone strip.

　　(2) Second-stage surgery: After two months of inserting the silicone strip, the implant is removed and a tendon transplant is performed within the artificial sheath.

　　9, Rehabilitation after flexor tendon repair:Adhesions are prone to occur after flexor tendon repair, and adhesions are the most important complication affecting function, followed by joint stiffness. The best way to avoid adhesions and joint stiffness is to maintain activity. To date, no suture material or suture method can allow patients to flex their fingers independently as soon as possible without causing rupture. Currently, various drugs and membranes to prevent adhesions are being tested, but their potential to prevent adhesions and other complications is not yet sufficient to widely promote various methods. In China, the most useful methods are controlled active movement (Kleinert method) and continuous passive movement, or a combination of both.

　　Kleinert restrictive dynamic splinting method: After surgery, the wrist joint is fixed in a 45° dorsal position and the metacarpophalangeal joint in a 60° flexion position using a dorsal plaster splint, which extends beyond the fingertips. A clothing hook is glued to the nail with 502 glue, a rubber band is hung, a safety pin is tied on the wrist band, and the other end of the rubber band is hung. Under its elasticity, the affected finger maintains a passive flexion position. Starting from the second day, active finger extension exercises are performed 50 times per hour. Passive flexion of the interphalangeal joints, flexion of each joint separately, and combined flexion, 5 times per hour. Due to the restriction of the dorsal plaster, the repaired flexor tendons slide within the sheath without being pulled apart under tension. The range of motion and frequency of practice are adjusted according to the severity of the injury and the patient's tolerance to pain. If there is more than 20° of insufficient extension at the proximal interphalangeal joint in the fourth week, an aluminum splint with a sponge pad is bound to the palmar side of the finger at night, fixing it in a straight position. In the fifth week, the splint is removed for 2 hours a day, performing 10 times of wrist joint active extension and flexion, and 10 times of finger comprehensive extension and flexion (40°～60°). In the sixth week, full extension and flexion are performed. In the seventh week, the dorsal splint is removed, and the resistance joint activities are gradually performed until the 12th week, when the normal function is completely restored. Physical therapy is indispensable during this period.

　　Continuous passive motion, equipped with commercially available CPM devices, initially fitted with type I, slowly pulling the fingers to extend and flex while keeping the wrist in a flexed position. After 4 weeks, type II is fitted, with coordinated extension and flexion of the fingers and wrist. China is in the trial production and trial operation stage, lacking mature experience.

　　Rehabilitation medicine in China is in the initial stage, and most hospitals and centers lack formal guidance by specialized physical therapists, which greatly reduces the effectiveness of flexor tendon surgery.

　　10. Flexor Tendon Release Surgery:In the era when the theory of exogenous healing dominated, tendon healing necessarily leads to adhesion. With the current surgical methods and postoperative rehabilitation routine treatment, the adhesion after tendon repair has been greatly reduced and alleviated. However, different authors still report that 15% to 41% of patients need a second-stage release surgery. Whether tendon release surgery is needed and whether it can achieve a good result requires a detailed examination by experienced specialists to decide. Blind exploration sometimes leads to excessive stripping, causing ischemic necrosis of the tendons, spontaneous rupture during exercise, and sometimes increased trauma and heavier adhesions.

　　The timing of tendon release should be after the tendons have healed, the wounds have softened, adhesions and scars have been reshaped through physical therapy. For patients with joint rigidity, tendon release is ineffective; for patients with joint stiffness, it must be performed when the joint has recovered a larger range of motion. It is generally believed that tendon repair should be released 3 months after surgery, and tendon transplantation should be released 6 months after surgery.

　　Tendon release surgery requires patient cooperation in movement, and can be performed under local anesthesia plus intravenous anesthesia. The operation must be performed under anticoagulation. The fingers are made with a full-length serrated incision, and all restrictive adhesions are systematically excised. Blood supply is preserved, as well as the pulley, and the A2, A4 annular ligaments are preserved to the minimum extent. After the pulley is reconstructed, the function will decrease. If there is significant adhesion between the superficial and deep flexor tendons, it is difficult to release them so that both can move effectively or may re-adhere, then the superficial tendon is excised and the deep tendon is preserved. Sometimes the superficial tendon slides well, but the deep tendon adhesion is heavy, making it difficult to become sliding, then the distal interphalangeal joint is fixed or fused in the functional position, and postoperative rehabilitation is very important for restoring function.

　　Research on the application of drugs, placement of biological membranes or synthetic interposition membranes to prevent recurrence of adhesions is numerous, but has not been recognized by the public.

　　II. Prognosis

　　The general prognosis is good.