osteomyelitis osteonecrosis.pptx

Osteomyelitis Tsitskari Maria MD,MSc, EBIR Apollonio Private Hospital Definition the word osteomyelitis originates from the ancient Greek words osteon and myelinos(marrow) inflammation process of the entire bone including the cortex and the periosteum, the pathological process is rarely confined to...

Osteomyelitis Tsitskari Maria MD,MSc, EBIR Apollonio Private Hospital Definition the word osteomyelitis originates from the ancient Greek words osteon and myelinos(marrow) inflammation process of the entire bone including the cortex and the periosteum, the pathological process is rarely confined to the endosteum Predisposing factors fractures due to trauma gun shot wounds radiation damage pages disease osteoporosis systemic disease : malnutrition, acute leukaemia,SCA, Classification ased on duration and type of symptoms: based on mechanism : exogenous ( trauma, surgery, contiguous infection hematogenous ( bacteremia) Acute osteomyelitis Age: infancy and childhood Sex: male predominate 4:1 Location: metaphysics of long bones poor nutrition, unhygienic surroundings Acute osteomyelitis etiological agents Acute osteomyelitis in infants joint involvement is common nutrient metaphysical capillaries perforate the epiphyseal growth plate, particularly in the hip, shoulder, and knee Acute osteomyelitis in infants Clinical features fever(high grade) child refuses to use limb local redness, swelling, warmth, oedema newborn: failure to thrive, drowsiness, irritable nutrient metaphysical capillaries perforate the epiphyseal growth plate, particularly in the hip, shoulder, and knee Acute osteomyelitis plain radiography The earliest changes are seen in adjacent soft tissues +/- muscle outlines with swelling and loss or blurring of normal fat planes An effusion may be seen in an adjacent joint osteomyelitis must extend at least 1 cm and compromise 30 to 50% of bone mineral content to produce noticeable changes in plain radiographs Early findings may be subtle, and changes may not be obvious until 5 to 7 days in children and 10 to 14 days in adults. Acute osteomyelitis plain radiography regional osteopaenia periosteal reaction/thickening (periostitis): variable, and may appear aggressive including formation of a Codman's triangle focal bony lysis or cortical loss endosteal scalloping loss of bony trabecular architecture new bone apposition eventual peripheral sclerosis Acute osteomyelitis plain radiography Osteomyelitis in the right foot of a 63-year-old male. (A) The dorso-plantar radiograph shows a periosteal reaction around the 1st metatarsal diaphysis (white arrowheads); (B) short axis coronal short-tau inversion recovery (STIR) image of the same patient demonstrating marked soft tissue oedema surrounding the 1st metatarsal. The periosteum (white arrowheads) is separated from the cortex (white arrow) by high signal material representing pus. There is a defect in the cortex (black arrow), known as a cloaca, that allows pus to drain from the medullary cavity into the subperiosteal space. Compared to the other metatarsals, the medulla (M) of the 1st metatarsal has high signal, consistent with bone marrow oedema. Acute osteomyelitis MRI MRI is most sensitive and specific and is able to identify soft-tissue/joint complications T1 ◦ the normal marrow has high T1 signal due to fat within the medulla In acute osteomyelitis, the bone marrow becomes congested with fluid and pus, producing low signal on T1W images and high signal on fluidsensitive and post-contrast sequences ◦ cortical bone destruction T2 ◦ bone marrow oedema ◦ central high signal (fluid) T1 C+ ◦ post contrast enhancement of bone marrow, abscess margins, periosteum and adjacent soft tissue collections Acute osteomyelitis MRI STIR T1 Acute osteomyelitis CT CT is superior to both MRI and plain film in depicting the bony margins and identifying a sequestrum or involucrum The CT features are otherwise similar to plain films The overall sensitivity and specificity of CT even in the setting of chronic osteomyelitis is low and according to one study was 67% and 50% sequestrum: is defined as a piece of devitalised bone that has been separated from its surrounding bone during the process of necrosis. - a complication of osteomyelitis - devascularisation of a portion of bone with necrosis and resorption of surrounding bone leaving a 'floating' piece - acts as a reservoir for infection and as it is avascular is not penetrated by antibiotics In some instances the sequestrum becomes encased in a thick sheath of periosteal new bone, known as an involucrum Acute osteomyelitis CT A cloaca can be found in chronic/acute osteomyelitis The cloaca is an opening in an involucrum which allows drainage of purulent and necrotic material out of the dead bone If the tract extends to the skin surface, the portion extending beyond the involucrum to the skin surface is called a sinus tract osteomyelitis chronic osteomyelitis  Hallmark is infected dead bone within a compromised soft tissue envelope  The infected foci within the bone are surrounded by sclerotic, relatively avascular bone covered by a thickened periosteum and scarred muscle and subcutaneous tissue chronic osteomyelitis Chronic osteomyelitis in a 9-year-old boy with a non-united left distal humerus fracture. (A) The lateral radiograph shows marked periosteal thickening (black arrowheads) and a central sclerotic lesion with a lucent rim (black arrow); (B) coronal CT with bone windows shows a sclerotic fragment of bone which is separate from the rest of the humerus (black arrow), consistent with a sequestrum. Cortical thickening is also noted (black arrowheads); this represents an involucrum which is a result of periosteal new bone formation. chronic osteomyelitis Chronic osteomyelitis in a 9-year-old boy with a non-united left distal humerus fracture. (A) The lateral radiograph shows marked periosteal thickening (black arrowheads) and a central sclerotic lesion with a lucent rim (black arrow); (B) coronal CT with bone windows shows a sclerotic fragment of bone which is separate from the rest of the humerus (black arrow), consistent with a sequestrum. Cortical thickening is also noted (black arrowheads); this represents an involucrum which is a result of periosteal new bone formation. subacute osteomyelitis Brodie abscess is an intraosseous abscess related to a focus of subacute pyogenic osteomyelitis. X-ray lytic lesion often in an oval configuration that is oriented along the long axis of the bone surrounded by a thick dense rim of reactive sclerosis periosteal new-bone formation +/- adjacent soft-tissue swelling ral intramedullary hypodense cystic lesion with thick rim ossification nsive thick well-circumscribed periosteal reaction and bone sclerosis around the lesion could be subacute osteomyelitis sclerosing osteomyelitis of Garre Bone is thickened and distended, but abscesses and sequestra are absent. Cause unknown Thought to caused by a low grade, possibly anaerobic bacterium sclerosing osteomyelitis of Garre Avascular Necrosis AVN Osteonecrosis Aseptic necrosis Ischemic necrosis Bone infarction Introduction Definition – Loss of blood flow to the bone leading to death of the cellular components of bone. Bones Affected Femoral head – most common by far Shoulder – humeral head Odontoid (Neck) Scaphoid (Wrist) Lunate (Wrist) Talus (Ankle) Examples Etiologies Trauma Alcohol Steroids Diving (Caisson’s Disease) Sickle Cell Idiopathic (up to 30% of cases) Symptoms Pain Decreased range of motion Staging Initially radiographic staging Revised with advancement of MRI Stage 0 No clinical symptoms No radiographic abnormalities Microscopic diagnosis Stage I May or may not have symptoms Radiographs and CT are normal MRI is abnormal as is bone scan Microscopic exam confirms diagnosis Stage II Patient is symptomatic X-rays show osteopenia, sclerosis, cysts No subchondral lucency or collapse MRI confirms diagnosis Stage II sclerosis subchondra l cysts Stage III X-rays show subchondral lucency and collapse – Crescent sign Shape of femoral head is preserved Subclassified by extent of crescent – IIIa 15% of head – IIIb 15-30% of ahead – IIIc greater than 30% Stage IV Flattening or collapse of head on x-ray Loss of joint space Subclassified by extent of collapse like Stage III – IVa – IVb – IVc MRI Stage IV Stage V Arthritic changes evident on x-rays with loss of joint space and spurring May affect acetabular side of the joint Stage V Stage VI Extensive destruction of femoral head and joint May be indistinguishable from osteoarthritis