Shoulder joint tuberculosis

　　1. Etiology

　　The incidence of shoulder joint tuberculosis is the lowest among the three major joints of the upper limb, most occurring in young and middle-aged adults aged 20 to 30. This disease is caused by the invasion of the tuberculosis bacteria into the blood circulation, retaining in the synovium of the joint or the metaphysis and causing infection.

　　2. Pathogenesis

　　The shoulder joint is more common with dry lesions, characterized by不明显, while mainly atrophy.

　　At first, the tuberculosis bacteria can be retained in the synovium of the joint or the metaphysis of the epiphysis through hematogenous retention, and then the infection enters the joint cavity (Campos, 1955; Bosworth, 1959).

　　The primary focus of tuberculosis originates in the epiphysis metaphysis, with bacterial and mycelial infiltration and diffusion, causing bone dissolution and necrosis, forming caseous material, accompanied by tuberculous granulation tissue, caseous material dissolved and liquefied into tuberculous pus, appearing bone destructive cavity (containing pus and dead bone), then pus enters the joint cavity, appearing synovial changes, leading to total joint tuberculosis.

　　The primary focus of tuberculosis originates in the synovium of the joint, develops slowly, and can appear bone destruction after several months or years. At the beginning of the disease, there is synovial tuberculosis inflammation, congestion, hyperplasia, hypertrophy, tuberculous granuloma nodules, producing serous exudation, joint effusion, fibrin deposition forming fibrin blocks, formation of tuberculous pus, invasion of marginal bone of the joint (subchondral destructive spread, cartilage necrosis and shedding), bone destruction, leading to total joint tuberculosis.

　　Joint abscess can penetrate the joint, forming a tuberculous sinus or fistula, and then secondary infection (Boyd, 1953).

　　Primary synovitis is rare, and the anatomical neck of the humerus and the glenoid cavity of the scapula are often the sites of invasion. The joint is filled with tuberculous granulation tissue. In children, the lesion can involve the entire diaphyseal end of the humerus. Many small scattered foci on the humeral head fuse into a large fibrous caseous cavity, causing deformation of the humeral head. The joint capsule becomes contracted, and the joint becomes fibrously rigid, often resulting in limited joint movement (Turek, 1977).

　　After the onset of shoulder joint tuberculosis, the muscles around the joint capsule, such as the deltoid muscle and supraspinatus and infraspinatus muscles, can quickly develop disuse atrophy. In a few cases, due to long-term downward drooping of the affected limb, the humeral head may become subluxated. If the lesion destroys the epiphysis of the humerus in children, it may lead to short-limbed deformity in the future.

　　Sometimes, the spread of tuberculosis from adjacent areas (such as the acromion or subacromial bursa) can also invade the shoulder joint. Tuberculosis of the supraclavicular fossa, axilla, or preaxillary lymph nodes can occasionally be complicated with shoulder joint tuberculosis.

　　The incidence of shoulder joint tuberculosis is very low, but it is insidious, and early diagnosis is difficult. Untimely treatment often causes serious sequelae to the patient, even amputation or death. In the late stage, sinus tract formation may also occur. It often breaks through the weakest part of the joint capsule, that is, near the axilla or the anterior edge of the deltoid muscle.

　　This disease often also complicates active pulmonary tuberculosis. In the late stage, it may be complicated by fibrous rigidity.

　　Early symptoms include localized dull pain, which is relieved during rest and worsened during exertion. Generally, there is no radiation pain. When a simple bone tuberculosis transforms into articular tuberculosis, the pain intensifies. In the early stages of articular tuberculosis, due to increased inflammatory exudate, the pressure within the joint cavity increases, resulting in severe pain. Later, the pus breaks through the joint capsule and flows into the surrounding soft tissue spaces, causing the joint pressure to decrease and the pain to diminish. When mixed infection occurs, the local area swells again, and the pain increases accordingly. In the late stage, the joint becomes fibrously rigid, and the pain disappears.

　　Simple bone tuberculosis rarely causes bone and joint movement disorders or only mild restriction, while articular tuberculosis results in significant movement disorders, with the affected arm unable to be lifted and rotation being severely limited. Abduction, flexion, and extension are also restricted, making it difficult to dress and undress.

　　The deltoid muscle and supraspinatus and infraspinatus muscles on the affected side are明显萎缩, even showing a 'square shoulder' deformity, known as 'dry tuberculosis'.

　　Most cases have developed into severe destructive articular tuberculosis, with some patients showing abscesses or sinus tracts. Diagnosis is not difficult, but it is not easy to achieve early diagnosis for simple synovial tuberculosis, simple bone tuberculosis, and early articular tuberculosis. During diagnosis, the medical history should be carefully inquired, combined with physical examination and X-ray findings. Attention should be paid to the discovery of tuberculosis lesions in other parts such as the lungs, pleura, and lymph nodes. Joint puncture fluid, pus culture, or guinea pig inoculation can confirm joint tuberculosis. The tuberculin skin test is helpful for diagnosis but is not specific, as a positive test only indicates that the patient has been exposed to tuberculosis and has increased sensitivity to it, but it cannot be confirmed that the patient has been infected with tuberculosis. However, if the test is negative repeatedly, tuberculosis can be excluded. In cases where clinical laboratory methods still cannot confirm the diagnosis, tissue biopsy can be performed to assist in diagnosis (especially when X-ray examination shows that the joint space has widened due to effusion, decalcification of the joint ends, and erosion of the joint surface).

　　1、及早诊断和治疗

　　如患有结核病，应及早诊治，以避免病情恶化和预防散播病菌；结核病患者可到任何一间胸肺科诊所接受治疗。

　　4

　　How to prevent shoulder joint tuberculosis

　　1. Early diagnosis and treatment

　　If tuberculosis is present, it should be diagnosed and treated early to avoid deterioration of the condition and to prevent the spread of the bacteria; tuberculosis patients can receive treatment at any chest and lung clinic.

　　2. Examination for those who have had close contact with tuberculosis patients

　　This is mainly for the examination of the family members of the patient, including the tuberculin skin test and/or lung X-ray for children, and lung X-ray examination for older children and adults.

　　4. BCG vaccination

　　The Department of Chest and Lung of the Health Bureau provides BCG vaccination services for all newborns in Hong Kong; for children under 15 years of age living in Hong Kong who have never been vaccinated with BCG, it is also recommended that they receive this vaccine injection.

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　　Shoulder joint tuberculosis: What laboratory tests are needed?

　　1. White blood cell count, erythrocyte sedimentation rate: The decrease in blood leukocyte count, the increase in lymphocyte ratio, and the acceleration of erythrocyte sedimentation rate during the active phase of the disease can reach over 100mm/h (Wessex method). Usually, changes in erythrocyte sedimentation rate occur earlier than X-ray findings, but erythrocyte sedimentation rate also accelerates in other inflammatory diseases and malignant tumors, and it is not a specific examination.

　　2. Guinea pig inoculation test

　　3. Tuberculosis culture: The positive rate is high, but the procedure is complex, expensive, and time-consuming (6 to 7 weeks), and it can be adopted if conditions permit.

　　The duration is long, requiring 3 to 6 weeks, with the highest positive rate of pus reaching 74.1%, followed by granulation tissue and caseous material, and synovial fluid and necrotic bone having the lowest positive rate. The average positive rate is 68.80%, and the positive rate is not related to the site of the lesion or the course of the disease.

　　4. Surgical exploration and biopsy

　　5. X-ray manifestations: Cold abscess or caseous material found during surgery can often confirm the diagnosis, and if there is still doubt, it can be confirmed by pathology with a positive rate between 70% and 80%.

　　6. CT examination: Early cases only show osteoporosis and soft tissue swelling. When X-ray signs appear, most have evolved into total joint tuberculosis, with bone destruction as the main manifestation. Bone destruction can occur at the acromion, humeral head, glenoid cavity, and greater tuberosity, with the formation of necrotic bone; more commonly, there is narrowing of the joint space and bone destruction at the joint margins. In advanced cases, bone destruction is severe, with part of the humeral head disappearing, even partial dislocation. Due to the destruction of the epiphysis at the upper end of the humerus, the humeral head may shrink or even disappear. Secondary infection may lead to bone sclerosis.

　　There is joint effusion, and joint marginal bone destruction can be detected early; in later cases, obvious bone destruction and necrotic bone can be shown, and the size and flow direction of cold abscesses in the extra-articular soft tissue spaces can also be shown.

　　7. MRI examination

　　It can detect the abnormal signals of joint effusion and bone inflammatory infiltration earlier.

　　Patients must strengthen their nutrition in terms of diet to compensate for the energy consumption caused by the disease. Tuberculosis patients should pay attention to a diet that is 'high in protein, high in calories, and high in vitamins'. The staple food, meat, eggs, vegetables, and soup should be reasonably matched. Eat more fruits and do not have a biased diet. For patients with severe tuberculosis, more light, tasty, nutritious, and easy-to-digest foods should be eaten.

　　1. Drug treatment

　　Isoniazid (isoniazid), ethambutol (ethambutol), and streptomycin (streptomycin) are usually used for treatment. If the patient is sensitive and effective to isoniazid and ethambutol, streptomycin may not be necessary. The duration of conservative treatment is 3 months per course, with at least 4 courses. Rifampin (Ri-fampin) is an effective drug for controlling bone and joint tuberculosis, especially when administered in combination with isoniazid. However, close observation should be made for side effects, with hepatotoxicity being common (Aguinas, 1972). Systemic and local anti-tuberculosis drug therapy can be adopted. In addition to systemic medication, 1g of streptomycin and 200mg of isoniazid can be injected locally into the joint, 1 to 2 times a week, with the same course as systemic medication. Pain can be alleviated by adding 1% procaine, and local medication can be used for 1 to 2 courses. There have been reports of patients infected with mycobacteria (mycobactin) who are not infected with tuberculosis and whose treatment with anti-tuberculosis drugs is ineffective, which deserves attention (Kelly, 1969).

　　2. Simple bone tuberculosis

　　Different surgical approaches are taken according to the location of the lesion.

　　(1) Tuberculosis of the acromion: The location is superficial and easy to expose. A longitudinal incision, transverse incision, or arc-shaped incision around the distal end of the acromion can be made according to the extent of the focus and abscess. If the acromioclavicular joint is also involved, it can be removed together. The affected limb is suspended with a triangular bandage for 3 weeks after surgery.

　　(2) Tuberculosis of the greater tubercle of the humerus: An incision is made around the greater tubercle of the humerus under the acromion. If there is an abscess, the incision can be appropriately anterior or posterior according to its location. The deltoid muscle is cut 1 cm away from the origin of the deltoid muscle along the direction of the incision, and it is pulled down along with the skin to expose the abscess. The abscess is incised, the pus is aspirated, and the focus is removed. After surgery, the affected limb is fixed with an abduction brace or suspended with a triangular bandage for 3 to 4 weeks.

　　(3) Tuberculosis of the humeral head or glenoid: According to the location of the abscess in the anterior or posterior shoulder, an anterior or posterior incision is used to enter the lesion. When removing the focus, attention should be paid not to cut the joint capsule. The postoperative fixation is the same as above.

　　3. Early total joint tuberculosis

　　Early total joint tuberculosis is the best indication for surgical treatment. Surgical treatment can not only quickly cure the lesion but also preserve most of the joint function. If the patient is old and weak and does not meet the conditions for surgery, only non-surgical therapy can be adopted, but the joint will eventually lose its function.

　　Surgical exposure has the anterior and posterior approaches to the shoulder joint. When clearing the focus, attention should be paid to:

　　(1) Cleanly remove the hypertrophic and edematous synovial tissue.

　　(2) The focus at the joint margin should be scraped clean, and there is often superficial bone destruction in the intertubercular groove.

　　(3) Check carefully whether the cartilage surface of the humeral head and scapular glenoid is intact, remove the damaged cartilage surface until healthy bone is exposed, and do not miss hidden bone foci.

　　After surgery, the affected limb is fixed with a Valpeau bandage, changed to a triangular bandage for suspension after 2 weeks of suture removal, and shoulder joint activities are started after 3 weeks of surgery.

　　4. Advanced Total Joint Tuberculosis

　　The purpose is to clear the focus and fuse the shoulder joint in the functional position, making the affected limb stable and strong. After the shoulder joint is fused in the functional position, due to the compensation of the acromioclavicular, sternoclavicular, and shoulder-thoracic joints, the patient can still abduct the upper limb by 90° and can still perform general work.

　　Surgery can be performed through the anterior approach, first clearing the focus, and then performing fusion. To promote joint bony fusion, bone grafting (autograft from the iliac bone) is often performed between the humeral head and scapular glenoid, between the greater tubercle of the humerus and the acromion, or between the coracoid process and the acromion and the greater tubercle. To maintain an ideal fusion angle and close contact between the joint bone ends, the shoulder joint can be fixed with 2 to 3 Steinman pins or with screws for acromial humeral head fixation. The position of fixation is 60° abduction, 30° flexion, and 25° external rotation, that is, the palm of the hand facing the patient's own mouth. After 3 weeks, the suture is removed, the Steinman pins are removed, and the shoulder figure-of-eight plaster is fixed until the joint bony fusion, usually requiring 3 to 4 months.

　　For elderly and weak patients, after the lesion is removed, the humeral head can be simply excised. The advantages are simple surgery and no need for long-term fixation after surgery; the disadvantages are weakened limb strength and reduced range of active movement. Functional exercise should be performed after surgery. Although the focus of chronic shoulder joint tuberculosis has been absorbed, for those with shoulder joint fixation in the adducted position, humeral neck osteotomy can be performed below the humeral head to improve the external rotation function of the shoulder joint.