Chronic non-specific infection of bone and joint

1. Chronic non-specific infection of bone and joint

2. Chronic osteomyelitis

3. Chronic osteomyelitis is a severe, persistent, and sometimes incapacitating infection of bone and bone marrow. It is often a recurring condition because it is difficult to treat definitively.

4. This disease may result from (1) inadequately treated acute OSM (2) a hematogenous type of osteomyelitis; (3) trauma, (4) iatrogenic causes such as joint replacements and the internal fixation of fractures; (5) compound fractures; (6) infection with organisms, such as Mycobacterium tuberculosisand Treponema species (syphilis); and (7) contiguous spread from soft tissues, as in diabetic ulcers or ulcers in peripheral vascular disease

5. Pathophysiology Infective process Osteomyelitis is an infective process involving all osseous components, including bone marrow. Chronic osteomyelitis results when the inflammatory process continues over time, leading to bone sclerosis and deformity. The ends of long bones are the most common locus of infection, and Staphylococcus aureus is the most common infective organism involved. Traumatic fractures or previous surgery may be responsible creating the access for infection, which may also originate from sepsis in the hematogenous form.

6. Pathophysiology Infection at the bone locus creates an increase of intramedullary pressure due to inflam matory exudate that strips the periosteum, leading to vascular thrombosis followed by bone necrosis and the formation of sequestra. Usually, necrosis of the large segments of bone leads to sequestrum formation. These sequestra with infected material are surrounded by sclerotic bone that is relatively avascular. The haversian canals are blocked with scar tissue, and the bone is surrounded by thickened periosteum and scarred muscle. Antibiotics cannot penetrate these relatively avascular tissues and are hence ineffective in clearing the infection. New bone formation occurs at the same time (involucrum). Multiple openings appear in this involucrum, through which exudates and debris from the sequestrum pass via the sinuses. A periosteal reaction acts to circumscribe the sequestrum, producing a thick sheet of new bone or involucrum.

7. Organisms Commonly Isolated in Osteomyelitis Infants (<1 year) Group B streptococci Staphylococcus aureusEscherichia coli Children (1 to 16 years)S. aureusStreptococcus pyogenesHaemophilusinfluenzaeAdults (>16 years) Staphylococcus epidermidisS. aureusPseudomonas aeruginosaSerratiamarcescensE. coli

8. OrganismComments Staphylococcusaureus  Organism most often isolated in all types of osteomyelitis Coagulase-negative staphylococci or Propionibacteriumspecies   Foreign-body­associated infection Enterobacteriaceae species or Pseudomonas aeruginosa Common in nosocomial infections Streptococci or anaerobic bacteria   Associated with bites, fist injuries caused by contact with another person's mouth, diabetic foot lesions, decubitus ulcers Salmonella species or Streptococcus pneumoniae Sickle cell disease Bartonellahenselae   Human immunodeficiency virus infection Pasteurellamultocida or Eikenellacorrodens   Human or animal bites Aspergillus species, Mycobacterium avium-intracellulare or Candida albicansImmunocompromised patients Mycobacterium tuberculosis   Populations in which tuberculosis is prevalent Brucella species, Coxiellaburnetii (cause of chronic Q fever) or other fungi found in specific geographic c

9. Anatomy Cierny and Mader proposed an anatomic classification of chronic osteomyelitis: Type 1 - Endosteal or medullary lesion Type 2 - Superficial osteomyelitis limited to the surface Type 3 - Localized, well-marked legion with sequestration and cavity formation Type 4 - Diffuse osteomyelitis lesions

10. Physiologic Factors affecting immune surveillance metabolism and local vascularity - Systemic factors (Bs): malnutrition, renal or hepatic failure, diabetes mellitus, chronic hypoxia, immune disease, extremes of age, immunosuppression or immune deficiency - Local factors (Bl): chronic lymphedema, venous stasis, major vessel compromise, arteritis, extensive scarring, radiation fibrosis, small-vessel disease, neuropathy, tobacco abuse

11. Frequency United States The prevalence of chronic osteomyelitis is 5-25% after an episode of acute osteomyelitis. The prevalence of tuberculous osteomyelitis is 1-5% of the population affected by tuberculosis. The incidence in developed countries is low. International The incidence in developing countries is higher than in other countries, although the exact incidence is not known. Mortality/Morbidity Mortality from osteomyelitis was 5-25% in the preantibiotic era. Presently, the mortality rate is approaching 0%. Complications of osteomyelitis include (1) septic arthritis, (2) destruction of the adjacent soft tissues, (3) malignant transformation (eg, Marjolin ulcer [squamous cell carcinoma], epidermoid carcinoma of the sinus tract), (4) secondary amyloidoses, and (5) pathologic fractures

12. Clinical presentation chronic forms of osteomyelitis usually occur in adults. Generally, these bone infections are secondary to an open wound, most often an open injury to bone and surrounding soft tissue. Localized bone pain, erythema and drainage around the affected area are frequently present. The cardinal signs of subacute and chronic osteomyelitis include draining sinus tracts, deformity, instability and local signs of impaired vascularity, range of motion and neurologic status. The incidence of deep musculoskeletal infection from open fractures has been reported to be as high as 23 percent.6 Patient factors, such as altered neutrophil defense, humoral immunity and cell-mediated immunity, can increase the risk of osteomyelitis

13. Presentation Unlike acute osteomyelitis, chronic osteomyelitis causes no acute constitutional symptoms. The presenting features may be those of a long-standing, discharging sinus or chronic bone pain and persist despite treatment. Patients may also present with acute exacerbations and usually have a previoushistory of acute osteomyelitis, sometimes dating back to childhood. Other symptoms include deep boring pain, especially in cases of a Brodie abscess. In osteomyelitis that occurs after joint replacement, the main symptom is the recurrence of pain. Findings in tuberculosis include the following: History of tuberculosis elsewhere Attacks of fever and lassitude Night cries Intense episodes of pain in the affected bones Muscle wasting, synovial thickening, and restriction of joint movement in all directions Kyphosis, back pain, and symptoms and signs of spinal cord compression in spinal tuberculosis Findings in syphilis include the following: Pain, refusal to move the affected limb Restriction of movement in an adjacent joint Pain in the bone Local swelling, redness, and warmth

14. Fever Nausea General discomfort, uneasiness, or ill feeling (malaise) Drainage of pus through the skin (in chronic osteomyelitis) Additional symptoms that may be associated with this osteomyelitis include the following: Excessive sweating Chills Low back pain Swelling of the ankles, feet, and legs Physical examination shows bone tenderness and, possibly, swelling and redness. During laboratory testing, a full blood count may show leukocytosis. The erythrocyte sedimentation rate (ESR) is elevated. Blood cultures may help identify the causative organism. Results of bone lesion biopsy and cultures may be positive for the organism. A skin lesion with a sinus tract (ie, the lesion tunnels under the tissues) may yield pus for culturing.

15. Diagnosis The diagnosis of osteomyelitis is based primarily on the clinical findings, with data from the initial history, physical examination and laboratory tests serving primarily as benchmarks against which treatment response is measured. Leukocytosis and elevations in the erythrocyte sedimentation rate and C-reactive protein level may be noted. Blood cultures are positive in up to one half of children with acute osteomyelitis. The palpation of bone in the depths of infected pedal ulcers in patients with diabetes mellitus is strongly correlated with the presence of underlying osteomyelitis (sensitivity, 66 percent; specificity, 85 percent; positive predictive value, 89 percent; negative predictive value, 56 percent).7 If bone is palpated, the evaluation may proceed directly to microbiologic and histologic confirmation of osteomyelitis, and thereafter to treatment. Further diagnostic studies are unnecessary. chronic stage of hematogenous osteomyelitis is known as a Brodie's abscess.

16. Histopathologic and microbiologic examination of bone is the gold standard for diagnosing osteomyelitis

17. microbiologic examination Cultures of sinus tract samples are not reliable for identifying causative organisms. Therefore, biopsy is advocated to determine the etiology of osteomyelitis.14 However, the accuracy of biopsy is often limited by lack of uniform specimen collection and previous antibiotic use

18. Laboratory Investigations • CBC with differential – Elevated WBC count – Left shift: Polymorphonucleocytosis • Blood cultures • ESR (Normal: < 20 mm/hr) – Usually elevated > 35mm • C-Reactive Protein (Normal: < 8 - 10mg/L) – Elevated > 10mg/L

19. Diagnostic Imaging • Plain Radiographs • Ultrasound • Radionuclide (Bone) Scans • C-T Scans • M R I

20. Radiography Findings Plain radiographic findings in acute or subacute osteomyelitis are deep soft-tissue swelling, a periosteal reaction, cortical irregularity, and demineralization. The chronic phase of the disease is characterized by thick, irregular, sclerotic bone interspersed with radiolucencies, an elevated periosteum, and chronic draining sinuses. Sclerosing osteomyelitis of Garré most commonly affects the mandible and appears with a focal sclerosingperiosteal reaction on radiologic studies. Chronic recurrent osteomyelitis is benign self-limiting condition that primarily affects long bones in children and adolescents. The metaphysis of long bones are usually affected, and changes may be symmetrical. The appearances are those of confluent areas of bone lysis. . False Positives/Negatives Stress fractures, osteoidosteomas, and other causes of periosteitis may mimic acute or chronic osteomyelitis.

21. Osteomyelitis, chronic. Sequestrum of the lower tibia

22. Osteomyelitis, chronic. Sclerosing osteomyelitis of the lower tibia. Note the bone expansion and marked sclerosis.

23. Sequelae of Osteomyelitis: Chronic • Sinus – Intermittent drainage • Sequestrum – Dead bone (sclerotic) – Failure to resorb • Involucrum – New bone envelope • Pathologic fracture

24. Computed Tomography CT is of definite value for studying the entire articular surface of bone and periarticular soft tissues; for delineating the extent of medullary and soft-tissue involvement; and for demonstrating cavities, serpiginous tracts, sequestra, or cloacae in osteomyelitis. CT scans sometimes show soft-tissue edema or bone destruction not seen on plain images, particularly in the setting of acute osteomyelitis. Sclerosis, demineralization, and periosteal reactions are usually well depicted in chronic osteomyelitis. CT scanning also helps in evaluating the need for surgery, and it provides vital information about the extent of disease. This data helps in planning appropriate surgery. CT is also an important modality in image-guided biopsy. False Positives/Negatives Stress fractures, osteoid osteomas, and other causes of periosteitis may mimic acute or chronic osteomyelitis

25. Osteomyelitis, chronic. Axial CT scans show destruction of L1. Note the air in the soft tissues

26. Osteomyelitis, chronic. CT scans show vertebral osteomyelitis associated with a psoas abscess

27. Osteomyelitis, chronic. Nonenhanced axial CT scans through the first and second toes in the same patient as in Images 5-7 shows cortical irregularity of the distal phalanx of the hallux; this finding is suggestive of chronic osteomyelitis. The final diagnosis was osteomyelitis of the first and second toes, plantar fasciitis, and psoriatic arthritis of the fifth metatarsal-phalangeal joint.

28. Magnetic Resonance Imaging Findings MRI findings in osteomyelitis are usually secondary to the replacement of marrow fat with water secondary to edema, exudate, hyperemia, and bone ischemia. Findings include the following: decreased signal intensity in the involved bone on T1-weighted images, increased signal intensity in the involved bone on T2-weighted image, and increased signal intensity in the involved bone on short-tau inversion recovery (STIR) images. Sequestrum of cortical bone appears hypointense on T1-weighted, T2-weighted, and STIR MRIs and shows no gadolinium enhancement. Sequestrum of cancellous bone is hyperintense relative to cortical sequestrum on T1-weighted, T2-weighted, and STIR MRIs and shows no gadolinium enhancement. The involucrumis hypointense on all 3 images and shows gadolinium enhancement. Granulation tissue is hypointense on T1-weighted images and hyperintense on T2-weighted and STIR images. It shows gadolinium enhancement. Similarly, draining sinuses and soft-tissue inflammation are hypointense on T1-weighted images and hyperintense on T2-weighted and STIR MRIs; however, it does show gadolinium enhancement. .

29. Osteomyelitis, chronic. T1- and T2-weighted sagittal MRIs show bone marrow edema in L1 and obliteration of the disk space between L1 and L2

30. Contrast: Gadolinium Enhancement T2 Weighted Image Gadolinium enhanced

31. MRI: Gold Standard • Soft tissue & bony changes • Changes appear early • Accurately localizes subperiosteal or soft tissue collections • Sensitivity of 100% for bone marrow edema • No ionizing radiation • Disadvantages: – Cost – Need for sedation in most infants and children

32. Degree of Confidence MRI has sensitivity and specificity higher than those of plain radiography and CT, and it is particularly good at depicting bone marrow abnormalities. On MRI, marrow signal abnormality is more sensitive than lytic changes on plain images, and findings become positive earlier with MRI than with radiography. Intramedullary bone pathology can be directly visualized with MRI, and in osteomyelitis marrow, these findings may precede bone changes. reaction and associated soft-tissue involvement

33. The multiplanar capability of MRI is an advantage and provides better anatomic detail and better soft-tissue contrast. MRI is especially good in assessing vertebral osteomyelitis, which has a characteristic pattern of confluent vertebral body and disk involvement. Titanium and other orthopedic devises usually pose no problem apart from artifacts. However, MRI findings of osteomyelitis are nonspecific, and similar changes can occur as a result of tumors, fractures, and a variety of other intramedullary or juxtamedullary processes that may cause bone marrow edema. The sensitivity and specificity has been reported as 92-100% and 89-100%, respectively. Prior fracture changes due to surgery or the fracture itself are difficult to differentiate from infection. False Positives/Negatives Fractures, bone bruises, and benign or malignant bone tumors may all mimic osteomyelitis.

34. Ultrasonography Findings Cleveland and Peck reported a case in which high-resolution ultrasonography was instrumental in establishing a diagnosis of chronic osteomyelitis. Sonograms depicted a periosteal

35. Nuclear Imaging Gallium-67 scanning. Technetium-99m diphosphonate bone scanning A99m Tc methylene diphosphonate (MDP) bone scans are usually positive 24 hours after an acute infection, and the scans demonstrate a well-defined focus of tracer activity 1-2 hours after the injection. This finding is correlated with radiotracer in same area on dynamic scans. Bone scintigraphy may show focal uptake at the affected site and is particularly valuable in looking for other sites of infection, as multifocal osteomyelitis may occur. MDP scans also remain positive in most patients with subacute and chronic osteomyelitis. Increased focal activity may persist in sterile disease for up to 2 years following successful therapy. The sensitivity of MDP scans can be improved by using a 3-phase bone scan. On such scans, focal activity is usually depicted associated with mild, diffusely increased, regional activity distal to the sight of osteomyelitis. Occasionally, a photon deficient (cold) defects are seen.

36. Osteomyelitis, chronic. Radiograph (left) and isotopic bone scans (right) show sclerosing osteomyelitis of the tibia

37. Radionuclide Imaging: Bone Scan • Technetium diphosphonate • New bone formation (osteoid) • Reflects osteoblastic activity • Higher sensitivity with longer duration of illness • Bone Scan can be -ve • Very early osteomyelitis • Absent blood supply • Neonates have less mineralization (30% sensitivity) • Useful for occult multifocal lesions

38. Osteomyelitis, chronic. Three-phase technetium-99m diphosphonate bone scans (perfusion component) show increased activity in the whole of the heel, the tarsus, the proximal and distal phalanges of the hallux, and the proximal phalanx of the second toe

39. Osteomyelitis, chronic. Indium-111–labeled WBC scans show an infected right-knee prosthesis

40. Bone scans, both anterior (A) and lateral (B), showing the accumulation of radioactive tracer at the right ankle (arrow). This focal accumulation is characteristic of osteomyelitis

41. Treatment Chronic osteomyelitis in adults is more refractory to therapy and is generally treated with antibiotics and surgical debridement. Empiric antibiotic therapy is not usually recommended. Depending on the type of chronic osteomyelitis, patients may be treated with parenteral antibiotics for two to six weeks. However, without adequate debridement, chronic osteomyelitis does not respond to most antibiotic regimens, no matter what the duration of therapy is. Outpatient intravenous therapy using long-term intravenous access catheters (i.e., Hickman catheters) decreases the length of hospital stays.28-30.

42. Treatment Oral therapy using fluoroquinolone antibiotics for gram-negative organisms is presently being used in adults with osteomyelitis.23 None of the currently available fluoroquinolones provides optimal antistaphylococcal coverage, an important disadvantage in view of the rising incidence of nosocomially acquired staphylococcal resistance.31 Furthermore, the current quinolones provide essentially no coverage of anaerobic pathogens

44. Debridement Acute hematogenous osteomyelitis is best managed with a four- to six-week course of appropriate antimicrobial therapy. Chronic osteomyelitis is generally treated with antibiotics and surgical debridement. Surgical debridement in patients with chronic osteomyelitis can be technically demanding. The quality of the debridement is the most critical factor in successful management. After debridement with excision of bone, it is necessary to obliterate the dead space created by the removal of tissue. Dead-space management includes local myoplasty, free-tissue transfers and the use of antibiotic-impregnated beads. Soft tissue procedures have been developed to improve local blood flow and antibiotic delivery

45. Specific forms of chronic osteomyelitis Other forms of chronic osteomyelitis include A Brodie abscess is a form of chronic osteomyelitis without a preceding episode of acute osteomyelitis.. Tuberculous osteomyelitis of the bone is secondary spread from a primary source in the lung or GI tract. It most commonly occurs in the vertebrae (body) and long bones. Once established, the bacilli provoke a chronic inflammatory reaction. Small patches of caseous necrosis occur, and these coalesce to form larger abscesses. The infection spreads across the epiphysis into the joints. The infection may track along soft tissue to appear as a cold abscess

46. congenital syphilis. The transplacental spread of spirochetes from mother to the fetus results in Long bones, such as the tibia, are mainly affected. Congenital syphilis has 2 forms: periosteitis and metaphysitis. In periosteitis, the periosteum is lifted of the diaphysis of long bone with subperiosteal new-bone formation. This process gives the characteristic appearance called sabre tibia. In metaphysitis, the juxtaepiphyseal metaphysis is involved with increased bone resorption. Absent osteoblastic activity results in separation of the epiphyseal from the metaphysis. acquired syphilis, bone lesions are manifestations of tertiary syphilis. Gummatous lesions appear as discrete punched-out radiolucent lesions in medulla or destructive lesions within the cortex. The surrounding bone is sclerotic, and no discharge is present.

47. A Brodie abscess is a subacute osteomyelitis with a predilection for the ends of long bones and the carpus and tarsus. Plain radiographic findings include the following: (1) a central area of radiolucency with a surrounding thick rim of reactive bone sclerosis, which may persist for months; (2) pathognomonic tortuous parallel lucent channels extending toward the growth plate; (3) a variable degree of periosteal new-bone formation; and (4) associated soft-tissue swelling.

48. A Brodie abscessis characterized by a double line at the site of the lesion due to the high signal intensity of granulation tissue surrounded by low signal intensity of bone sclerosis on T2-weighted MRIs. The lesion has low-to-intermediate signal intensity that is outlined by a hypointense rim on T1-weighted MRIs.

49. Brodie’s abscess, a localised radiolucency usually seen in the metaphyses of long bones. It is sometimes difficult Treatment of Brodie’s abscess in the metaphysis includes surgical curettage

50. Tuberculosis of Spine Tuberculosis of Skeletal System