Hello Hivers! In today's article, we'll talk about Osteomyelitis. Osteomyelitis is a heavy healthcare burden worldwide, especially in developing countries. Let's go.
Osteomyelitis is an infection of the bone. It is caused usually by a bacterial organism. Any bone in the body can be affected; however, it usually affects the long bone of the leg, especially tibia. It occurs in any age group but more common in the growing bones of children and adolescents.
In the USA, the prevalence is 1 per 5000 children. In neonates, 1 per 1000 children and sickle cell disease, the incidence is 0.36%. For the causes, foot puncture accounts for 16% and diabetics accounts for 30% to 40%. Internationally, there is a higher incidence in developing countries. It commonly affects males than females in a ration of 2:1. Depending on the nature of the organism, mechanism of infection and the host reaction, osteomyelitis can be classified into acute, subacute and chronic. Acute osteomyelitis is usually a haematogenous infection from distant focus meaning it is spread through blood from a point of infection such as an injury to the bone. Other ways of haematogenous spread are through intravenous drug abusers, haemodialysis and in debilitating disease. Another route of infection other than haematogenous is contiguous spread. This is caused by penetrating trauma, open fracture, surgical reduction of a closed fracture, bacterial contamination of orthopaedic prosthesis during surgery and spread from a cutaneous ulcer, sinus or dental infection. Haematogenous spread is commoner in children less than 2 years and 8 to 12 years. It is mostly direct trauma in adolescents and adults. Spinal osteomyelitis is a common cause in adults greater than 45 years. Risk factors include increased virulence of organisms, sickle cell disease, diabetes, immunodeficiency states like HIV, chemotherapy and malnutrition. Sources of infection include puncture wounds, boils & paronychia, dental caries, meningitis, etc. The organisms responsible for causing osteomyelitis to include Staphylococcus aureus (90%), Streptococcus pyogenes & Streptococcus Pneumonia (4%), Haemophilus influenza(5% to 50% and in children less than 4 years) and Gram-negative organisms like Escherichia coli, Pseudomonas eroginosa, Proteus mirabilis Enterobacter spp., Bacteroides Fragilis and Peptococcus magnus. Salmonella infections are also often seen in those with sickle-cell anaemia.
Drawing of Staphylococcus bacteria. By www.scientificanimations.com CC BY-SA 4.0, Link
In the USA, the prevalence is 1 per 5000 children. In neonates, 1 per 1000 children and sickle cell disease, the incidence is 0.36%. For the causes, foot puncture accounts for 16% and diabetics accounts for 30% to 40%. Internationally, there is a higher incidence in developing countries. It commonly affects males than females in a ration of 2:1. Depending on the nature of the organism, mechanism of infection and the host reaction, osteomyelitis can be classified into acute, subacute and chronic. Acute osteomyelitis is usually a haematogenous infection from distant focus meaning it is spread through blood from a point of infection such as an injury to the bone. Other ways of haematogenous spread are through intravenous drug abusers, haemodialysis and in debilitating disease. Another route of infection other than haematogenous is contiguous spread. This is caused by penetrating trauma, open fracture, surgical reduction of a closed fracture, bacterial contamination of orthopaedic prosthesis during surgery and spread from a cutaneous ulcer, sinus or dental infection. Haematogenous spread is commoner in children less than 2 years and 8 to 12 years. It is mostly direct trauma in adolescents and adults. Spinal osteomyelitis is a common cause in adults greater than 45 years. Risk factors include increased virulence of organisms, sickle cell disease, diabetes, immunodeficiency states like HIV, chemotherapy and malnutrition. Sources of infection include puncture wounds, boils & paronychia, dental caries, meningitis, etc. The organisms responsible for causing osteomyelitis to include Staphylococcus aureus (90%), Streptococcus pyogenes & Streptococcus Pneumonia (4%), Haemophilus influenza(5% to 50% and in children less than 4 years) and Gram-negative organisms like Escherichia coli, Pseudomonas eroginosa, Proteus mirabilis Enterobacter spp., Bacteroides Fragilis and Peptococcus magnus. Salmonella infections are also often seen in those with sickle-cell anaemia.
Drawing of Staphylococcus bacteria. By www.scientificanimations.com CC BY-SA 4.0, LinkPathology
The bone is supplied by three kinds of blood vessels. The nutrient artery is the major blood supply to the marrow, medulla and certain aspects of the cortex. Periosteal vessels supply the periosteum covering the bone and the outer cortex of the bone and Metaphyseal and epiphyseal vessels. Infection usually occurs in the metaphysis of long bones. Acute inflammation results in raised intraosseous pressure and intravascular thrombosis. This causes suppuration which in turn produces a subperiosteal abscess that may discharge into soft tissues. The spread of infection into epiphysis can result in joint infection and within days bone death can occur. Fragments of dead bone become separated in medullary canal (sequestrum - a piece of necrotic tissue, usually bone, that has become separated from the surrounding healthy tissue) and new bone forms below stripped periosteum (involucrum - the sheath of new bone that forms around a sequestrum). If infection rapidly controlled resolution can occur but if the infection is poorly controlled, chronic osteomyelitis can develop. The periosteum is infants is loosely attached to the underlying bone. Therefore, pus easily elevates the periosteum. Pieces of dead bone especially if cortical or surrounded by pus, are not resorbed and remain as sequestra. Sequestra is denser than surrounding vital bone, therefore, appearing more radio-opaque on X-ray. The vital bone becomes demineralised due to hyperaemia and immobilization. Involucrum forms beneath vital periosteum. In areas of dead periosteum, defects in involucrum occur called cloacae. These cloacae allow pus and sequestrate to escape to the skin via a sinus.Clinical features
The child usually presents with pain, malaise and fever. They are often unable to bear weight. Early signs of inflammation are often few. The bone is often exquisitely tender with reduced joint movement. Late infection presents with soft-tissue swellings or discharging sinus. Diagnosis can be confirmed by aspiration of pus from abscess or metaphysics. 50% of patients have positive blood cultures. Radiology can also help diagnose osteomyelitis. X-rays can appear normal during the first 3 to 5 days. In the second week, radiological signs may include periosteal new bone formation, patchy rarefaction of metaphysics and metaphyseal bone destruction. X-ray reveals osteoporosis within 10 -14 days and involucrum after 3 weeks of infection. It also shows swelling, with oedema and blurring of fat planes. In cases of diagnostic doubt, bone scanning can be helpful. CT scan can reveal sequestra (fragments of bone within an area of local bone destruction) as areas of dense or high attenuation spicules of bone lying in the area of osteolysis. CT also shows the cloacae, periostitis and local soft tissue mass. A CT guided biopsy of the bone can also be done to culture and identify the organism responsible for easier faster treatment. MRI is the modality of choice in the diagnosis of musculoskeletal infection. It reveals changes of bone and soft tissue oedema, ischemia and destruction of the cortex, soft tissue extension of pus through cloacae and para-osseous abscess. Skeletal scintigraphy in suspected bone infection should rightly precede plain film examination. This is because plain radiographic changes cannot be seen for up to 10 -14 days with simple infections. Using scintigraphy, the diagnosis of osteomyelitis can be confirmed as early as 48 hours after the onset of the disease. Standard techniques involve the use of technetium 99m labelled phosphonate and phosphate compounds. Two sets of images are seen. ‘Blood pool image of the painful area’ which shows increased radioactivity in areas of increased blood flow and 'delayed skeletal scintigraphic images' at 3 – 4 hours; by this time, the radionuclide has been absorbed into the bone crystal. It gives a skeletal image with local accentuation in areas of increased blood flow and bone turnover. Skeletal scintigraphy is although not specific since tumours and infection may give a similar appearance. Gallium 67 labelled citrate scans can be used; in vitro indium labelled leucocytes. Differential diagnosis of osteomyelitis includes cellulitis, acute suppurative arthritis, rheumatic fever and sickle-cell crisis.Management
General supportive measures should include intravenous fluids and analgesia. Painful limb often requires a splint of skin traction to relieve the pain. Aggressive antibiotic therapy should be instituted; flucloxacillin is often the antibiotic of choice. If it fails to respond to conservative treatment, surgery may be required. A subperiosteal abscess should be drained and drilling of metaphysis is occasionally required. Overall, about 50% of children require surgeryComplications
Metastatic infection can occur at distant sites (e.g. brain, lung). It may spread into the joint and can result in septic arthritis. This complication occurs in young children in whom the growth plate is permeable, bones in which the metaphysis is intracapsular and the epiphysis of bones involved in metastatic infection. Involvement of physis can result in altered bone growth and failure to eradicate infection can result in chronic osteomyelitis.Do you have any questions, concerns or anything to add? Tell me what you think below.
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Originally posted here: https://hive.blog/hive-196387/@gamsam/acute-osteomyelitis-1597567831
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