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Recent Applications of Ultrasound Visualization in Musculoskeletal Disorders

With the continuous development of science and technology, minimally invasive interventional treatment of musculoskeletal diseases is becoming more and more popular. How to intervene more accurately is the medical industry more concern at present, which is the key to improving the efficacy of treatment. Musculoskeletal ultrasound technology has been a major trend in emerging ultrasound examination technology in recent years. Since this visual diagnosis and treatment method entered the field of rehabilitation and pain medicine, it has received extensive attention.

A new medical breakthrough: How can orthopedics reshape the diagnosis and treatment of diseases under the guidance of ultrasound?

In the traditional examination of skeletal system diseases, X-ray and CT are mostly relied on, while the examination of sports diseases depends more on MR. However, the above-mentioned inspection methods are all large-scale inspections, which cannot be applied to clinical treatment, and are all subject to site and radiation restrictions. Moreover, relying on body surface positioning requires too much experience of physicians, and some patients with obesity and anatomical variation are prone to accidental injury and poor treatment effects. Using high-frequency ultrasound to diagnose musculoskeletal system diseases can clearly display superficial soft tissue structures such as muscles, tendons, ligaments, and peripheral nerves and their lesions, such as abnormal tissue structures caused by inflammation, tumors, injuries, and injuries deformities. Physicians can use portable ultrasound to observe static and moving tissues in a real-time, non-invasive diagnostic environment, especially dynamic observation of bone and soft tissue movement, providing more efficient and reliable information for diagnosis. Physicians can also directly puncture the target tissue under the guidance of real-time ultrasound for precise targeting, which greatly promotes the development of safer and more effective treatment methods.

What is tenosynovitis?

Tenosynovitis is a common abnormality of wrist tendons in modern society. Before understanding tenosynovitis, let us look at the structure of the tendon sheath in order to better understand the cause of this disease. The tendon sheath is a double-layer casing-like closed synovial tube that covers the tendon, which is the synovial sheath that protects the tendon. The tendon sheath is composed of two layers, the inner layer is closely attached to the tendon, and the outer layer is lined in the tendon fiber sheath, and together with the bone surface, it has the functions of fixing, protecting and lubricating the tendon, preventing it from friction or compression. The cavity between the two layers is the synovial cavity, which is filled with synovial fluid of the tendon sheath.

Tendon is the transmission tissue of muscle force, which needs to complete the functions of flexion, extension and rotation through the joint. The flexor tendon is prone to friction when it passes through the protuberance of the metacarpophalangeal joint and the origin of the deep and superficial tendon sheaths. Under long-term stimulation, aseptic inflammatory reaction occurs in the tendon and tendon sheath, and local exudation and edema occur. Tenosynovitis is the clinical symptom (pain and dysfunction) caused by tendon sheath organization, sheath wall hypertrophy, narrow lumen, and limited movement of tendon in the tendon sheath.

Causes of tenosynovitis

The causes of tenosynovitis can be divided into primary and secondary. Primary tenosynovitis is mainly caused by overwork. Primary tenosynovitis can easily be caused by frequent stretching and flexing of fingers or by holding hard objects for a long time. The former is due to the repeated friction and extrusion of the flexor tendon in the bony fiber tube, while the latter is because the bony fiber tube is squeezed by a hard object and the palm bone, resulting in local congestion and edema of the bony fiber. Secondary tenosynovitis is mainly secondary to related diseases such as rheumatism, diabetes, and gout. Among them, it is especially obvious in rheumatic patients, and tenosynovitis is often their first symptom. The incidence of tenosynovitis in diabetic patients is 5-7 times that of normal people.

Classification of tenosynovitis

1. Acute fibrous tenosynovitis

Lesions develop in the connective tissue around the synovium, and edema, hyperemia can be observed. It is characterized by fibrils of connective tissue rubbing around the edematous tendon with a soft rubbing sound, hence the name rubric synovitis. It often occurs in the upper part of the wrist, in the muscle belly of the extensor carpi radialis brevis tendon and the abductor pollicis longus and extensor pollicis brevis. It is also called crepitus tenosynovitis. 2. Acute serous tenosynovitis

Acute serous tenosynovitis, also called rheumatic tenosynovitis, is a part of systemic rheumatism and response to acute rheumatic fever. Patients generally suffer from high fever, arthralgia, swelling, and effusion, and the most important pathological change is rheumatic myocarditis. After the fever subsided, the serous fluid of the tendon sheath exuded and absorbed, and the tenosynovitis healed itself. 3. Acute suppurative tenosynovitis

It often occurs after trauma, especially puncture injuries, mostly in the flexor tendons of the wrist and fingers. In the early stage of infection, tenosynovitis will occur, and then the tendon will lose its luster, turn gray or green, and be infiltrated and necrotic by pus. The most common pathogens are staphylococci, followed by streptococci. 4. Tuberculous tenosynovitis

Caused by Mycobacterium tuberculosis infection. First, the synovial membrane of the tendon sheath is injured, and it spreads from the palm along the ulnar and radial bursa to the forearm through the carpal tunnel. The tendon sheath is hypertrophic due to the infiltration of tuberculosis granulation tissue, and the sheath contains yellow exudate and yellow rice grains. Gradually, the tendon is also infiltrated by granulation tissue to form nodules and hypertrophy, losing its original smooth and dynamic function. When granulation tissue invades other tendon sheaths and nerves, it can cause flexion and sensory disturbances. 5. Stenosing tenosynovitis A disease caused by thickening and narrowing of the sheath due to repeated friction. Fingers, toes, wrists, and ankles are the most common. The severity of stenosing tenosynovitis can be divided into Ⅰ-Ⅲ degrees: Grade I: The affected finger only manifests as morning stiffness, local pain and tenderness, without snapping and locking.

Grade II: In addition to local pain, the swelling and nodules of the tendon sheath can still be palpable, but the extension and flexion functions can be independently completed.

Grade III: Grade II symptoms are further aggravated, local nodules enlarge, frequent interlocking and snapping occurs, and the affected finger needs to be extended and flexed outside.

Common radial styloid stenosing tenosynovitis, flexor tendonitis, plantar flexor tenosynovitis.

1. Radial styloid stenosing tenosynovitis: Stenosing tenosynovitis of the radial styloid process occurs at the bony process (radial styloid process) on the thumb side of the wrist. It is manifested by obvious pain around the bony process, blocked thumb movement, and local tenderness. During self-examination, you can hold your thumb tightly in the other four fingers, and do wrist flexion to the inside of the wrist, and severe pain will appear during the radial styloid process.

2. Flexor tendon tenosynovitis: Stenosing tenosynovitis of the flexor tendon, also known as trigger finger, is a sterility-verified lesion caused by chronic injury of the tendon and tendon sheath. The etiology is that the size of the flexor tendon at the first annular (A1) trochlear is inconsistent with that of the retinaculum trochlear system surrounding it. The A1 trochlea overlies the metacarpophalangeal (MCP) joint. The flexor tendon locks up as it tries to slide through the relatively narrow tendon sheath, preventing smooth flexion and extension of the fingers. The affected finger manifests as flexion and extension dysfunction, the pain sometimes radiates to the wrist, there is tenderness at the flexion of the finger joint, and the thickened tendon sheath and pea-sized nodules can be touched, also known as "trigger finger" or "elastic finger". Snap your fingers". 3. Plantar flexor toe tenosynovitis: Prolonged standing and walking in high heels is the main cause of plantar flexor tenosynovitis in women. The center of gravity of the body moves forward, and the gravity of the whole body is concentrated on the front of the sole of the foot. Over time, friction between the tendon sheath and tendon, inflammation exudation, etc. induce tendon sheath narrowing or inflammation.

Ultrasonographic Diagnosis of Stenosing Tenosynovitis

High-frequency musculoskeletal ultrasonography is the modality of choice for stenosing tenosynovitis. The finger flexor tendon pulley system is a layer of dense connective tissue bundle, under normal circumstances, the thickness is less than 1mm, and the diseased tissue can be clearly displayed under high-frequency ultrasound. Specifically, it can be observed that:

1. Thickening of the tendon sheath, uneven or reduced echo

2. The synovial layer of the tendon sheath may have a thin liquid dark area

3. The tendon is swollen and thickened, and the tendon at the pulley is squeezed and thinned

4. The local blood flow signal of the tendon sheath increases in the acute stage

Treatment for Tenosynovitis

The traditional treatment method is that physicians inject analgesic drugs based on experience, but the affected area is prone to multiple recurrences and progressive aggravation after surgery, resulting in severe bone destruction. With the continuous innovation and iteration of medical equipment, the current ultrasound-guided visualization of local closure injection and release is a new type of precise treatment method. High-frequency musculoskeletal ultrasound clearly shows the lesion site of stenosing tenosynovitis, and distinguishes important blood vessels, nerves and other tissue structures around it. At the same time, the injection needle tip is visualized during the injection process, which is convenient for doctors to determine the recommended target and recommended dose. Easily to achieve accurate and safe treatment effects, and patients do not need to be hospitalized for treatment.

Ultrasound-guided needle-knife release visualization therapy

1. Preparation: After establishing the local anesthesia channel for the skin, perform the "two-step method" A1 pulley release under the guidance of ultrasound. At each step, place the transducer longitudinally on the volar metacarpophalangeal joint and scan laterally to distinguish between the ulnar and radial sides (the midpoint of the transducer is over the tendon). 2. Dilation: At the 3mm distal end of the base of the proximal phalanx, use 16G Abbocath to establish the puncture point entry (PEN) of the tendon sheath on the palmar side under the guidance of ultrasound, and then pass the 1.5mm long Kirschner wire needle through the PEN to enter the proximal cutting point (At the metacarpophalangeal joint), the thumb is located 3mm proximal to the metacarpal head-neck junction, and the rest of the fingers are located 5mm proximal to the metacarpal head-neck junction. 3. Loosening: introduce the hook-shaped needle knife into the tendon sheath, then push it to the metacarpophalangeal joints, turn the needle knife facing upward toward the palm, press the knife handle to cut, and finally pull out the needle knife along the puncture point. The release is successful when the trigger sensation disappears and the affected finger is active. 4. Postoperative tips: The postoperative skin wound is only 1mm wide, no need to suture, just stick the adhesive dressing, which can be torn off after 2 days, and the patient can return to normal life on the same day. Physicians can encourage patients to continue active and passive finger exercises in all directions during the day. 5. Precautions: The patient's body position and the surgical area should be disinfected, and the affected hand should be wrapped with a sterile surgical drape to maintain a sterile environment on the operating table during the operation. Due to the fixed display area and long cables of traditional desktop ultrasound, it can only ensure the sterility of the probe part. Wireless hand-held ultrasound should be used to guide the needle-knife to advance. Just put the ultrasound and mobile phone in a sterile bag to achieve a completely sterile environment and minimize the risk of surgical infection. During the operation, it is necessary to ensure that the instrument is accurately positioned at the metacarpophalangeal joint so as not to cut any proximal neurovascular crossing structures (especially the trigger finger of the thumb). Therefore, high-definition and delicate portable ultrasound imaging can improve the success rate of the operation and greatly reduce the difficulty of operation. It is recommended to select a high-frequency linear array probe (depth <3 cm) for ultrasonic long-axis and short-axis slice examinations. Conclusion Accurate treatment of stenosing tenosynovitis with ultrasound-visualized needle-knife can be accurate and safe, and can effectively avoid nerve and blood vessel damage. Even for local drug injection therapy, precise positioning can be achieved under the guidance of portable ultrasound, and a very small amount of drug is used to achieve reliable results and reduce side effects caused by drug diffusion to normal tissues. High-frequency portable ultrasound can clearly display lesions such as tendons, ligaments, bursae, and nerves, and has become an important inspection method for superficial soft tissue lesions, and has the characteristics of real-time dynamics, no radiation, and low price. It can guide the accurate positioning of the needle knife to treat soft tissue diseases, and the visualized needle knife under the guidance of portable ultrasound can accurately treat musculoskeletal diseases, which is an effective way to complete accurate diagnosis and precise treatment.

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