Bone and joint subcutaneous node (tuberculosis of bone and joint) is a local manifestation of systemic subcutaneous node infection. Its occurrence is mostly caused by subcutaneous node bacilli migrating from the primary lesion through the bloodstream and settling in the bone end or the bone membrane of the joint. It is the most common type of extrapulmonary subcutaneous node. It can occur at any age, with 75-80% of patients being under 14 years old, and the highest incidence is between 2-6 years old. Trauma is often a predisposing factor. Common sites of occurrence in children include the spine, as well as joints such as the hip, knee, and ankle.

bubble_chart Clinical Manifestations

The onset is insidious, with local symptoms initially being inconspicuous. The first manifestations are systemic symptoms of tuberculous intoxication, such as low-grade fever, listlessness, loss of appetite, fatigue, emaciation, and night sweating. Local symptoms gradually appear later. Almost all cases have a history of tuberculous contact, and the OT or PPD test is positive.

1. Spinal tuberculosis
   1. Pain: This is a nerve root irritation symptom, presenting as radiating pain. For example, thoracic spinal tuberculosis pain may radiate to the sternum or intercostal regions, while lower thoracic pain may radiate to the abdomen and lumbar region. The affected vertebrae exhibit tenderness and percussion pain.
   2. Spinal rigidity: Due to protective muscle spasms in the affected area, movement is restricted to avoid pain. In children, after falling asleep, the muscles relax, and pain occurs during involuntary movements, often leading to night crying. Examination may reveal hardened paravertebral muscles, sometimes appearing rope-like and raised. The "pick-up test" can be performed: the child is asked to bend forward to pick up an object from the ground. The child cannot bend the waist forward or downward but instead adopts a squatting posture with knees bent, or supports the bent knee with one hand while picking up the object with the other. This test is highly significant for diagnosing spinal tuberculosis.
   3. The spine develops a fixed kyphotic deformity, and the child assumes a characteristic protective posture to reduce pressure on the affected vertebrae. For example, in thoracic spinal tuberculosis, the child often maintains a posture with raised shoulders and an expanded chest, while in lumbar spinal tuberculosis, the abdomen protrudes forward, the feet are kept apart, and the gait is waddling, resembling a duck’s walk.
   4. A cold abscess may form at the site of spinal damage, and hip extension may be limited. Further vertebral destruction can lead to spinal cord compression symptoms, such as urinary incontinence, loss of skin sensation below the lesion, hyperreflexia, and ankle clonus.
   5. X-ray findings: Early stages show narrowed intervertebral spaces and osteoporosis. In advanced stages, vertebral destruction appears wedge-shaped, and sometimes the paravertebral soft tissue shadow deepens into a spindle shape, indicating the formation of a cold abscess.
2. Hip joint tuberculosis
   1. Leg pain: Rarely confined to the hip joint, it often radiates to the anterior and medial aspects of the knee joint, initially intermittent and relieved by rest, later becoming persistent. Children may experience night terrors, a characteristic feature of hip joint tuberculosis.
   2. Limping: While walking, the child primarily bears weight on the unaffected limb, resulting in a limping gait. This posture reduces pain. The affected hip joint has limited mobility, the quadriceps muscle atrophies, and the affected limb shortens.
   3. Thomas sign positive: The child lies supine and holds the healthy knee flexed while attempting to extend the affected leg. If the affected leg cannot be fully extended, it suggests hip joint pathology.
   4. X-ray findings: No abnormalities may be detected in the first few weeks. Early changes include osteoporosis, a shallow and flattened acetabulum, followed by bone destruction at the femoral head or acetabular rim, narrowed joint space, and in severe cases, extensive bone destruction, pathological dislocation of the femoral head, complete joint destruction, or fibrous ankylosis leading to loss of mobility.
3. Knee joint tuberculosis
   1. Early symptoms include mild limping and pain, initially intermittent and relieved by rest, worsening with activity, and possibly presenting as throbbing pain at night. Limping and pain may become persistent and worsen over time.
   2. The joint swells into a spindle shape, and effusion in the joint cavity may cause fluctuation and a floating patella on palpation.
   3. The thigh muscles on the affected side atrophy, and the knee develops flexion deformity. The suprapatellar bursa thickens, feeling dough-like on palpation. Movement disorders arise; if the joint capsule is filled with tuberculous granulation tissue, knee extension is limited, and the joint assumes a flexed position. The thigh is slightly externally rotated, a posture that alleviates pain. Further epiphyseal destruction leads to limb shortening, joint deformity, progressive worsening, and eventual flexion at a right angle.
   4. X-ray findings: Anteroposterior and lateral views of the knee joint may show localized osteoporosis early on, followed by blurred trabeculae and bone destruction at the epiphyseal ends. The joint space narrows, and the periarticular soft tissues swell. Sometimes, a cold abscess may be visible.
   5. Joint puncture to find subcutaneous node bacteria or biopsy.
4. Phalangeal and metacarpal subcutaneous node
   1. Most commonly seen in children under 5 years old.
   2. It is multiple, with spindle-shaped enlargement of the finger or metacarpal bones, without symptoms such as redness, swelling, heat, or pain.
   3. X-ray films may reveal small translucent areas in the center of the diaphysis, which gradually expand and almost fill the entire diaphysis, causing spindle-shaped swelling of the diaphysis. The bone cortex is extremely thin, and sometimes cortical hyperplasia may be seen, forming a layer of dense shadow. As the disease progresses, sequestrum may form, leading to pathological dislocation of the phalanges. The affected side is longer than the healthy side.

bubble_chart Treatment Measures

(1) General Treatment

Bed rest, enhanced nutrition, and administration of multivitamins.

(2) Anti-subcutaneous node drug therapy: Choose dual therapy or triple therapy for severe cases.

1. INH + SM + PAS (or EBM) INH: 1–1.5 years; SM: 3–6 months; PAS: 6–12 months; EMB: 6–9 months.
2. INH + RFP INH: 1–1.5 years; REP: 6–12 months

(3) Local Treatment

1. Skin traction: For children with deformities, skin traction is used to correct flexion deformities and maintain functional positioning, which can alleviate muscular rigidity and pain.
2. Gypsum fixation: For those without deformities, gypsum fixation is used to restrict movement, replaced every $ months, with joint function monitored.
3. Surgical treatment: Lesion debridement can be performed with good results. For simple synovial membrane subcutaneous nodes, simple synovectomy may be performed. Joint fixation may be considered for joint subcutaneous node patients over 12 years old.

(4) Treatment of Spinal Subcutaneous Nodes and Associated Paraplegia Based on systemic treatment and adequate use of anti-subcutaneous node drugs, the following measures are applied:

1. Rest on a hard board bed or use gypsum fixation.
2. Cold abscess puncture for pus drainage to alleviate systemic toxic symptoms.
3. For complete paraplegia, surgical exploration and lesion debridement with anterolateral decompression are performed. For incomplete paraplegia, conservative treatment is first tried for 2–3 months; if ineffective, surgical treatment is adopted. Spinal fusion may be considered after full recovery.

(5) For children with paraplegia, intensive nursing care is required, including regular turning and padding to prevent bedsore formation. Additionally, measures should be taken to prevent hypostatic pneumonia and respiratory infections.