Infections of Bone and Joint

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Infections of Bone and Joint
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Osteomyelitis
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Introduction

• Osteomyelitis is an inflammation of bone caused
  by an infecting organism.
• It may remain localized, or it may spread through
  the bone to involve the marrow, cortex,
  periosteum, and soft tissue surrounding the bone.
• The term is only applied to the infection caused
  by pyogenic bacteria not including inflammation
  of TB.

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Classification

• Attempts to classify osteomyelitis have been
  based on
• (1) the duration and type of symptoms
• (2) the mechanism of infection
• (3) the type of host response to the infection.
• Based on the duration and type of symptoms,
  osteomyelitis may be acute, subacute, or chronic

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Classified according to mechanism

• Osteomyelitis may be
• exogenous
• hematogenous.
• The exogenous form is an infection caused by
  trauma, surgery (iatrogenic), or a contiguous
  infection.
• The hematogenous form may result from known or
  unknown bacteremia.

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Periosteal medullits???

• The infection may involve the marrow spaces,
  Haversian canals and subperiosteal space. When
  all the bony components are involved, it means.
• Staphylococcus Aureus is the most common
  etiologic agent, causative bacteria or causal
  organisms.
• Today we also pay attention to the infection of
  Staphylococcus Epidermidis, the gram-negative
  anaerobic bacilli.

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Organisms may reach the bone by one of following
3 paths

• 1)directly through a skin wound which
  communicated with the bone, usually as a
  complication of the open fracture, and it is not
  often present as acute process.

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Organisms may reach the bone by one of following
3 paths

• 2)directly spread from a neighboring soft tissue
  infection or adjacent infective focus
• 3)indirectly via the blood stream, - Hematogenous
  spread.
• The blood stream is invaded from a minor
  abrasion or boil (furuncle), sore throat,
  gingivitis. It intends to be more acute.
  Hematogenous spread is the most common route of
  infection by far.

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Acute hematogenous osteomyelitis

• From any focus of infection, organisms often
  enter the blood stream to form the temporary
  bacteremia, but they can not survive in the major
  of cases.
• If they reach an area that the vitality of the
  tissue is lower than normal, they may multiply
  and reproduce.

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Acute hematogenous osteomyelitis

• Although the normal bone has an excellent blood
  supply, there is slowing of the circulation in
  the metaphyseal region.
• Acute hematogenous osteomyelitis occurs most
  frequently in meduallary cavity of long bones and
  in children usually begin in the metaphysic.

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The pathogenic organisms easily settle in the
metaphysis at the growing end of long bone
possibly because

• 1.knee is liable to be injuried, traumatic
  hematomas is a suitable medium for bacteria
  growth.
• 2.the more rapidly the bone grows, the more blood
  supply is. In long bone, the growing end has more
  blood flow, the hairpin arrangement of
  capillaries has slowed down the rate of blood
  flow.
• 3.the rapid growing cells are susceptible
  affected by traumatic infection. Metaphysis is
  the relative lack of phagocytes, so the upper end
  of the tibia and the lower end of the femora are
  the most commonly infected part.

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Pathological change

• organisms enters , blocks, settles, multiply
• Hyperemia (congestion) tension builds up
• Exudates, a suboeriosteal abscess.
• it spreads, re-enter the bone, deprived of its
  blood supply.
• forced down the medullary canals, destroying the
  marrow blood supply

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Pathological change

• The cortex may be surrounded externally and
  internally by pus and deprival of its blood
  supply.
• As a result, unless the early evacuation of the
  pus, a segment of bone dies and eventually
  separates to form a sequestrum.
• The bone dies when its blood supply is cut off by
  infective thrombosis. The nutrient artery to
  endanger large area of the diaphysis, - liable to
  pathological fracture.

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Pathological change

• The importance of early decompression.
• Eventually the abscess bursts through the
  periosteum into the soft tissue.
• Perforation, and along fascial planes.
• Finally, it may through the skin to the surface
  and form a chronic sinus becoming a persistent
  sinus tract or cloaca.
• By this time, sinus or sequestrum formed, the
  disease has reached the chronic stage.

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Clinical features history

• The onset is rapid and attacks in short time.
• The patient, usually a child or adolescent,
• complains a severe pain in a limb, and the pain
  is not relieved by rest.
• A complete history and physical examination are
  required to search for possible primary foci of
  infection. There may be some minor injury or
  insignificant infective lesion such as boil sore
  throat a few days earlier.

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The general symptoms of toxemia

• ?severe acute illness appear
• ?irritable and restless
• ?high fever, chill
• ?rapid pulse, nausea, vomiting etc

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local signs

• caloric, rubor, dolor, tumor
• Heat, red, pain or tenderness, swelling
• Initially, the lesion is within the medually
  cavity, there is no swelling, soft tissue is also
  normal.
• The merely sign is deep tenderness.
• Localized finger-tip tenderness is felt over or
  around the metaphysic.
• it is necessary to palpate carefully all
  metaphysic areas to determine local tenderness,
  pseudoparalysis

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Subperiosteal abscess formation

• Edematous, red and fluctuation
• indicating subperiosteal abscess formation.
• As the subperiosteal abscess formed, signs of
  inflammation followed rapidly.
• The extremity is held in semiflexion,
• surrounding muscles are in spasm
• passive movement is resisted

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Clinic pictures

• An increase effusion in the adjacent joint proves
  in most cases to be a sympathetic synovitis with
  sterile clear fluid. Hydroarthrosis should not be
  confused with septic arthritis.
• It is important to remember that the metaphysis
  lie within the joint capsule of the hip,
  shoulder, ankle. Therefore these joints can
  develop septic arthritis by extension of
  osteomyelitis.
• If the infection and septicemia proceeded
  unabated, the patient may have toxic shock
  syndrome.

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Laboratory findings

• The white blood cell count will show a marked
  leulocytosis as high as 20,000 or more
• The blood culture demonstrates the presence of
  bacteremia, the blood must be taken when the
  patient has a chill, especially when there is a
  spiking temperature.
• Aspiration. The point of maximal tenderness
  should be aspirated with a large-bore needle.
• The thick pus may not pass through the needle.
• Any material aspirated should be gram stained and
  cultured to determine the sensitivity to
  antibiltics.

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X-ray findings

• x-ray films are negative within 1-2 weeks,
• Although carefully comparison with the opposite
  side may show abnormal soft tissue shadows.
• It must be stressed that x-ray appearances are
  normal in the acute phase. There are little value
  in making the early diagnosis.
• by the time there is x-ray evidence of bone
  destruction, the patient has entered the chronic
  phase of the disease.

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Bone scans

• Radioisotopic bone scaning was valuable in early
  localization(within 48 h) of bone infection.
  
• The specificity of radioactive isotopic imaging
  techniques have improved in the evaluation of
  musculoskeletal infection.
• Tc99m imaging is very sensitive , it is the
  choice for acute hematogenous osteomyelitis, the
  overall accuracy was 92.

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Prompt diagnosis

• The acute infection of bones can be cured by
  prompt appropriate antibiotic therapy.
• Bone and joint show special problems for the host
  defense mechanism because of its rigid structure.
  
• Once pus forms under pressure, the vascular
  supply is lost, resulting in areas of infected ,
  devitalized bone.
• Septic emboli in bone or vascular thrombosis can
  cause additional devascularization.
• Antibiotics can inhibit or cure an infection only
  when they can reach the infecting organisms.
• Infections producing pressure in a bone as well
  as relatively avascular tissues can impede or
  prevent antibiotics from reaching the primary
  site of infection.

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Prompt diagnosis

• Unfortunately the time between initial infection
  and circulatory embarrassment is often rather
  short (perhaps as early as 72 hours after the
  beginning of infection).
• Even under the best of circumstances, if
  treatment is undertook lately the end result
  might be the loss or abnormal function.
• The early diagnosis and rapid initial treatment
  is extremely important.

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Early diagnosis depends on fllowings

• 1. severe acute illness, rapid onset and toxemia
• 2. local severe pain and unwillingness to move
  limbs
• 3.deep tenderness
• 4.WBC count is as high as 20,000 or more
• 5.every effort must be made to obtain a bacterial
  culture and determinate the sensitivity to
  antibiotics
• Tc99m scaning
• CT or MRI

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Differential diagnosis

• 1. soft tissue infection such as cellulitis, deep
  abscess
• 2.acute suppurative/septic arthritis
• 3.Rheumatic fever less acute, polyarticular
  involvement, increased ASO
• Ewings sarcoma x-ray shows onion-peel bone
  deposition

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Treatment

• ! 1.general treatment nutritional therapy or
  general supportive treatment by intaking enough
  caloric, protein, vitamin etc.
• 2. antibiotics therapy
• 3.surgical treatment
• 4.immobilization

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antibiotics therapy

• early, large dosage, sensitive and continued
• The prompt administration of antibiotics is so
  vital that the result need not be waited, usually
  using wide-spectrum antibiotics, even by
  intravenous administration during the first 1-3
  days.
• The choice of antibiotics may subsequently be
  modified according to culture, sensitivity
  results, and clinical response.
• The treatment should be continued for at least 2
  weeks after the body temperature is down to the
  normal in order to minimize the possibly of
  reoccurrence.

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surgical treatment

• Pressure exerted by pus enclosed within a rigid
  compartment is tremendous.
• Circulation of the bone is destroied, antibiotics
  can not reach the organism and there will has
  extensive necrosis of bone,
• As any infection in a closed space, immediate
  provision of drainage is of paramount importance.
  
• This must be done at earliest possible
  opportunity even before signs of subperiosteal
  abscess is evident.
• To wait is to invite disaster.

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surgical treatment

• Surgery is indicated if an abscess is present
  regardless of the clinical course. It is
  indicated when there has been no response to
  vigorous antibiotics treatment after 48-72 hours.
  
• Surgery is achieved by making a skin incision
  over the most tenderness site, dividing the
  peristeum and opening the medullary cavity using
  either a series of drill holes or gauging out a
  window in the bone cortex to decompress rather
  than debridement.

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immobilization

• when the infected area is immobilized,
• the patient is more comfortable
• relieving pain
• to treat the infection by resting the limbs and
  ensue the healing process.
• If the damage to the bone is significant, cast
  immobilization may be important to prevent a
  pathologic fracture, remains for many weeks.
• If the damage to articular cartilage is
  suspected, traction might prevent further
  destruction but still allow joint mobility. In
  acute osteomyelitis of the upper femur, traction
  is needed to prevent hip dislocation.

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Treatment

• It is very difficult to provide a permanent cure
  for chronic osteomyelitis, most antibiotics fail
  to penetrate the barrier of fibrous tissue plus
  bone sclerosis.
• Chronic osteomyelitis presents quite different
  problem from the acute form. Its primary problem
  is surgical removal of all dead and poor
  vascularized tissues.
• If this is properly done under appropriate
  antibiotic therapy, the operation must be
  carefully planed as it often means significant
  removal of bone and surrounding tissues.
• Since the introduction of local muscle flap
  procedures, the success rate is 93 with local or
  vascularized flap, debridement and antibiotics.

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Chronic osteomyelitis

• If any of sequestrum, abscess cavity, sinus tract
  or cloaca is present.
• Hematogenous infection with an organism of low
  virulence may be present by chronic onset.
• Infection introduced through an external wound
  usually causing a chronic osteomyelitis.
• It is due to the fact that the causative organism
  can lie dormant in avascular necrotic areas
  occasionally becoming reactive from a flare up.

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Clinical features

• During the period of inactivity, no symptoms are
  present.
• Only Skin-thin, dark, scarred, poor nourished,
  past sinus, an ulceration that is not easily to
  heal
• Muscles-wasting contracture, atrophy
• Joint-stiffness
• Bone-thick, sclerotic,
• often contain abscess cavity

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Clinical features

• At intervals, a flare-up occurs,
• The relapse is often the result of poor body
  condition and lower resistance.
• A lighting up of infection is manifested by
  aching pain that is worse at night.
• Locally there will be some heat, swelling,
  redness,tenderness, edema, because pus may build
  up in cavity,then a sinus may open and start to
  exudates purulent materials and small sequestra.
• The sinus closed and the infection subsided.

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X-ray findings

• In the early stage, the bone appears at
  moth-eaten change and osteoporosis, then
  sclerosis develops.
• The periosteum is elevated by subperiosteal
  lamination of new bone which becomes thick and
  dense progressively.

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Treatment

• It is very difficult to provide a permanent cure
  for chronic osteomyelitis, most antibiotics fail
  to penetrate the barrier of fibrous tissue plus
  bone sclerosis.
• Chronic osteomyelitis presents quite different
  problem from the acute form. Its primary problem
  is surgical removal of all dead and poor
  vascularized tissues.
• If this is properly done under appropriate
  antibiotic therapy, the operation must be
  carefully planed as it often means significant
  removal of bone and surrounding tissues.
• Since the introduction of local muscle flap
  procedures, the success rate is 93 with local or
  vascularized flap, debridement and antibiotics.

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Septic arthritis

• The most common - Staphylococcus aureus.
• The hips and knees are the most frequently
  affected sites.
• Route of infection
• Hematogenous spread from an infective focus
• Spread from an adjacent focus
• Direct introduction by the wound

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Pathology

• 1.       serous arthritis
• Synovium is congested, edematous and
  infiltrated with WBC. Synovial fluid increased in
  the amount with clear or slight opaque appearance
  and slight amount WBC
• 2.      serofibrinous
• arthritis-fibrin is
  excessive
• 3.    purulent arthritis synovium-inflammation
  is more intense, areas of vascular thrombosis and
  local necrosis occurjoint fluid-WBC 2-5105/mm3,
  opaque, thick gray or yellowish in colourthe
  prolytic enzymes dissolve the articular
  cartilage, even erode the bone---fibrous
  ankylosis

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Diagnosis

• If a joint is suspected of being infected,
  aspiration with a large-bore needle should be
  performed promptly and before antibiotic therapy
  is begun.
• Careful skin preparation before aspiration is
  mandatory, and the fluid obtained should be sent
  for immediate Gram staining, culture, cell
  counts, and crystal analysis.

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3 essential principles in the management

• (1) the joint must be adequately drained,
• (2) antibiotics must be given to diminish the
  systemic effects of sepsis
• (3) the joint must be rested in a stable
  position.
• Prompt, adequate evaluation of purulent joint
  fluid appears to be crucial both for preservation
  of articular cartilage and for resolution of the
  infection.

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Treament

• If the diagnosis is made early and the involved
  joint is superficial, such as the elbow or ankle,
  aspiration should be performed and repeated if
  necessary, appropriate antibiotics should be
  administered, the joint should be splinted in a
  position of function, and the patient should be
  observed for a decrease in pain, swelling, and
  temperature and for improved joint mobility.

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Treament

• Initial antibiotic treatment is empirically based
  on the patients age and the risk factors.
• Empirical antibiotic therapy should be used until
  culture and sensitivity results are available.
• Although some infections clear up within 7 days,
  antibiotic regimens often should be continued for
  4 to 6 weeks, depending on the clinical course.

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Treament

• As the infection resolves, therapy to restore
  normal joint function is begun, including
  functional splinting initially to prevent
  deformity, isometric muscle strengthening, and
  active range-of-motion exercises.
• Patients being treated for infectious arthritis
  often have varying degrees of deformity, and
  treatment with traction, dynamic splints, serial
  casting, and passive exercises may be useful.