OSTEOMYELITIS.pptx. .....

Osteomyelitis

1. OSTEOMYELITIS Dr.Akshay (Com-PT)

2. This can be primary ( haematogenous ) or secondary (following an open fracture or bone operation). Haematogeous osteomyelitis is the commonest, and is often seen in children. ACUTE OSTEOMYELITIS

3. Metaphysis of the long bones : It is a highly vascularised zone. From the diaphysis the medullary arteries reach up to the growth plate; the area of greatest activity, and branch into capillaries. The venous system begins in this area and drains toward the diaphysis. Thus, the vessels in this zone are arranged in the form of a loop (hair-pin arrangement). The blood stasis resulting from such an arrangement is probably responsible for the metaphysis being a favourite site for bacteria to settle, and thus a common site for osteomyelitis . Anatomy

4. In most joints, the capsule is attached at the junction of the epiphysis with the metaphysis i.e., the metaphysis is extra-articular. In some joints, part of the metaphysis is intra-articular, so that the infection from the metaphysis can spread to the joint, resulting in pyogenic arthritis. Anatomy

5. Vascular arrangement at metaphysis of a long bone

6. Types of metaphysis. a) Extra-articular b ) Intra-articular

7. Staphylococcus aureus is the commonest causative organism. Others are Streptococcus and Pneumococcus . These organisms reach the bone via the blood circulation. Primary focus of infection is generally not detectable. The bacteria, as they pass through the bone, get lodged in the metaphysis. Lower femoral metaphysis is the commonest site. The other common sites are the upper tibial, upper femoral and upper humeral metaphyses . AETIOPATHOGENESIS

8. The host bone initiates an inflammatory reaction in response to the bacteria. This leads to bone destruction and production of an inflammatory exudate and cells (pus). Once sufficient pus forms in the medullary cavity, it spreads in the following directions. a) Along the medullary cavity: Pus trickles along the medullary cavity and causes thrombosis of the venous and arterial medullary vessels. Blood supply to a segment of the bone is thus cut off. Pathology

9. b) Out of the cortex: Pus travels along Volkmann’s canals and comes to lie sub- periosteally . The periosteum is thus lifted off the underlying bone, resulting in damage to the periosteal blood supply to that part of the bone. A segment of bone is thus rendered avascular ( sequestrum ). Dimensions of this segment vary from a small invisible piece to the whole diaphysis of the bone. Pus under the periosteum generates sub-periosteal new bone (periosteal reaction). Eventually the periosteum is perforated, letting the pus out into the muscle or subcutaneous plane, where it can be felt as an abscess. The abscess, if unattended, bursts out of the skin, forming a discharging sinus. Pathology

10. c) In other directions: The epiphyseal plate is resistant to the spread of pus. At times it may be affected by the inflammatory process. The capsular attachment at the epiphysis metaphysis junction prevents the pus from entering the nearby joint. In joints with an intra-articular metaphysis, pus can spread to the joint, and cause acute pyogenic arthritis e.g., in the hip, in the shoulder etc. Pathology

11. Spread of pus from metaphysis. a) Along medullary cavity, b) Out of the cortex, c) To the joint

12. X-rays showing different sizes of sequestra in osteomyelitis

13. The diagnosis of acute osteomyelitis is basically clinical. It is a disease of childhood, more common in boys, probably because they are more prone to injury. Presenting complaints: The child presents with an acute onset of pain and swelling at the end of a bone, associated with systemic features of infection like fever etc. Often the parents attribute the symptoms to an episode of injury, but the injury is coincidental. One may find a primary focus of infection elsewhere in the body (tonsils, skin, etc.). DIAGNOSIS

14. The child is febrile and dehydrated with classic signs of inflammation – redness, heat, etc. localised to the metaphyseal area of the bone. In later stages, one may find an abscess in the muscle or subcutaneous plane. There may be swelling of the adjacent joint, because of either sympathetic effusion or concomitant arthritis. Examination

15. Investigations provide few clues in the early phase of the disease. • Blood: There may be polymorphonuclear leucocytosis and an elevated ESR. A blood culture at the peak of the fever may yield the causative organism. • X-rays: The earliest sign to appear on the X-ray is a periosteal new bone deposition (periosteal reaction) at the metaphysis. It takes about 7-10 days to appear. Investigations

16. ULTRASONOGRAPHY: Ultrasonography may detect a subperiosteal collection of fluid in the early stages of osteomyelitis , but it cannot distinguish between a haematoma and pus. RADIONUCLIDE BONE SCANNING : Radioscintigraphy with 99mTc-HDP (Technetium-99m hydroxymethylene diphosphonate ) reveals increased activity in both the perfusion phase and the bone phase. This is a highly sensitive investigation, even in the very early stages, but it has relatively low specificity and other inflammatory lesions can show similar changes. In doubtful cases, scanning with 67Gallium-citrate or 111Indium-labelled leucocytes may be more revealing. Investigations

17. MAGNETIC RESONANCE IMAGING: Magnetic resonance imaging can be helpful in cases of doubtful diagnosis, and particularly in suspected infection of the axial skeleton. It is also the best method of demonstrating bone marrow inflammation . It is extremely sensitive, even in the early phase of bone infection, and can therefore assist in differentiating between soft-tissue infection and osteomyelitis . However, specificity is too low to exclude other local inflammatory lesions Investigations

18. Any acute inflammatory disease at the end of a bone, in a child, should be taken as acute osteomyelitis unless proved otherwise. Following are some of the differential diagnosis to be considered: a) Acute septic arthritis: This can be differentiated from acute osteomyelitis by the following features in arthritis: • Tenderness and swelling localised to the joint rather than the metaphysis. • Movement at the joint is painful and restricted. • In case of doubt, joint fluid may be aspirated under strict aseptic conditions, and the fluid examined for inflammatory cells. DIFFERENTIAL DIAGNOSIS

19. b) Acute rheumatic arthritis: The features are similar to acute septic arthritis. The fleeting character of joint pains, elevated ASLO titre ( Antistreptolysin O T itre ) and CRP values may help in diagnosis . Normal Range – titre less than 200units/ml for adults titre less than 400units/ml for children c) Scurvy: There is formation of sub-periosteal haematomas in scurvy. These may mimic acute osteomyelitis radiologically, but the relative absence of pain, tenderness and fever points to the diagnosis of scurvy. There may be other features of malnutrition. d) Acute poliomyelitis: In the acute phase of poliomyelitis, there is fever and the muslces are tender, but there is no tenderness on the bones. DIFFERENTIAL DIAGNOSIS

20. Treatment depends upon the duration of illness after which the child is brought. Cases can be arbitrarily divided into two groups: TREATMENT

21. a) If the child is brought within 48 hours of the onset of symptoms: If a child is brought early, it is supposed that pus has not yet formed and the inflammatory process can be halted by systemic antibiotics. Treatment consists of rest, antibiotics and general building-up of the patient. The limb is put to rest in a splint or by traction. Choice of antibiotics varies from centre to centre. It broadly depends upon the age of the child and choice of the doctor. In children less than 4 months of age, a combination of Ceftriaxone and Vancomycin in appropriate dose is preferred. In older children, a combination of Ceftriaxone and Cloxacillin is given. Antibiotics are started after taking blood for culture and sensitivity. Antibiotics are changed to specific ones depending upon the culture and sensitivity report. Treatment

22. The child is adequately rehydrated with intravenous fluids. Response to the above treatment is evaluated by frequent assessment of the patient. A four hourly temperature chart and pulse record is maintained. It is a good idea to outline the area of local tenderness precisely, with the help of the back of a match stick over regular intervals. If the patient responds favourably , fever will start declining and local inflammatory signs will diminish. As the child improves, the limb can be mobilised. Weight bearing is restricted for 6-8 weeks. After 2 weeks, antibiotics can be administered by oral route for 6 weeks. If the patient does not respond favourably within 48 hours of starting the treatment, surgical intervention is required. Treatment

23. b) If the child is brought after 48 hours of the onset of symptoms: If the child is brought late or if he does not respond to conservative treatment, it is taken for granted that there is already a collection of pus within or outside the bone. Detection of pus is often difficult by clinical examination because it may lie deep to the periosteum. An ultrasound examination of the affected part may help in early detection of deep collection of pus. Surgical exploration and drainage is the mainstay of treatment at this stage. A drill hole is made in the bone in the region of the metaphysis. If pus wells up from the drill hole, the hole is enlarged until free drainage is obtained. A swab is taken for culture and sensitivity. The wound is closed over a sterile suction drain. Rest, antibiotics and hydration are continued post-operatively. Gradually, the inflammation is controlled and the limb is put to use. Antibiotics are continued for 6 weeks. Treatment

24. This can be divided into two types, general and local: General complications: In the early stage, the child may develop septicaemia and pyaemia . Either complication, if left uncontrolled, may prove fatal. Local complications: It is unfortunate that a large number of cases of acute osteomyelitis in developing countries develop serious complications. Most of these are because of delay in diagnosis, and inadequate treatment. Some of the common complications are as follows: COMPLICATIONS

25. 1. Chronic osteomyelitis : It is the commonest complication of acute osteomyelitis . There are hardly any radiological features in the early stage. A delay in diagnosis leads to sequestrum formation and pent-up pus in the cavities inside the bone. Poor host resistance is another reason for the chronicity of the disease. 2. Acute pyogenic arthritis: This occurs in joints where the metaphysis is intra-articular e.g., the hip (upper femoral metaphysis), the shoulder (upper humeral metaphysis), etc. 3. Pathological fracture: This occurs through a bone which has been weakened by the disease or by the window made during surgery. It can be avoided by adequately splinting the limb. 4. Growth plate disturbances: It may be damaged leading to complete or partial cessation of growth. This may give rise to shortening, lengthening or deformity of the limb. Complications

26. X-rays of forearm of a child showing osteomyelitis of the radius. The X-ray on the right shows the sequestration of the whole shaft.

27. This condition arises from a wound infection in open fractures or after operations on the bone. The incidence of these cases are on the rise because of increase in operative intervention in the treatment of fractures. The constitutional symptoms are less severe than those in haematogenous osteomyelitis as the wound provides some drainage. The condition can be largely prevented by adequate initial treatment of open fractures, and adherence to sterile operating conditions for routine orthopaedic operations. SECONDARY OSTEOMYELITIS

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