Osteomyelitis in adults

Osteomyelitis in adults

 

Pathophysiology

Necrosis of the bone. (Contrast with inflammation in Acute Osteomyelitis)

History 

 

Osteomyelitis in adults usually presents in a patient with diabetes or/and  peripheral arterial disease. Usual presentation –  an ulcer or a soft tissue infection.  It should be suspected in patients with  with direct trauma or a history of orthopedic surgery. Most probably it can be seen in  the patient with diabetes and peripheral vascular disease. If untreated it can be complicated by open fracture . Almost 27% of incidence of Osteomyelitis develop into open fracture within 3 months if untreated.

Signs and symptoms

 

  • Presentation may be delayed up to 6 weeks or more after symptom onset
  • Localized bone pain
  • Erythema and swelling at affected area
  • Draining sinus tracts
  • Decreased range of motion of adjacent joints
  • Diminished blood supply
Types of osteomyelitis

 

I.Open Fracture
II. Contigiuous spread from soft tissue infection. Mostly if there is Diabetic Neuropathy and Peripheral Vascular Disease. This is the most common cause of the disease.
III. Hematogenous spread from bacteremia. Mostly common in children, less common in adults.
IV.Vertebral Osteomyelitis- Usually presents with back pain. It is mostly seen with IV Drug Abuse, Diabetes Mellitus, Chronic Kidney Disease, or cancer
V.Long bones, Pelvis and clavicle- rarely, but may be  affected as well.

Diagnostic Testing

 

I.Imaging tests

I.Best initial test: Plain x-ray
II. Best second test (if there is clinical suspicion and x-ray is negative): MRI. It  is the next best test to do to determine the diagnosis of osteomyelitis. A bone scan is not a specific test in diagnosis of osteomyelitis.
III. Most accurate diagnostic test in this case: bone biopsy and culture

Imaging  tests (XRay, bone scan, MRI) in osteomyelitis will demonstrate contiguous soft tissue infection or bony destruction. However,before X -ray becomes abnormal, more than  than 50 percent of the calcium content of the bone must be lost. That means, that abnormal X-ray will be seen only after two weeks of the onset of the disease. Nevertheless, X-ray exam should be always performed first.

II. Signs suggestive of contiguous Wound Infection spread to bone

Exposed bone
Persistent sinus tract
Tissue necrosis over the bone
Chronic wound overlying  bone Fracture
Chronic wound overlying surgical hardware (hip implant)

III. Lab tests

These are not specific tests however they are suggestive of inflammation or infection

  • Blood Cultures positive (Test Sensitivity is usually less than 50%).
  • C-Reactive Protein (C-RP)- will be increased
  • Erythrocyte Sedimentation Rate (ESR)- will be increased.This test is the best method of following a response to the therapy.If ESR is still markedly elevated after 4–6 weeks of therapy,- treatment is ineffective and treatment options should be reconsidered. Further treatment and possible surgical debridement maybe  necessary.

IV. Most Predictive Tests of Osteomyelitis

a)Probe-to-Bone Test
b)Skin Ulceration over a  the bony prominence

  • Ulcer present over 2 weeks
  • Ulcer is over 2 cm in size
  • Ulcer depth exceeds 3 mm
Differential diagnosis

 

  • The earliest sign of osteomyelitis on an x-ray is the elevation of the periosteum.
  • Involucrum and sequestrum of the bone are terms applied to the formation of abnormal new bone in the periosteum and chunks of bone chipped off from the infection.
  • Punched-out lesions are seen in myeloma.
  • Osteomyelitis usually does not have an association with bone fracture.
Treatment

 

Staphylococcus is  the most common cause of osteomyelitis. If the organism is sensitive, the first choice of treatment is  oxacillin or nafcillin intravenously for 4–6 weeks. Oral antibiotics are not considered in this case.
MRSA is treated with vancomycin, linezolid, ceftaroline, or daptomycin. You cannot use oral therapy for staphylococcal osteomyelitis.
Gram-negative bacilli ( most often it is caused by Salmonella and Pseudomonas )- this the one and only
form of osteomyelitis that can be  treated with oral antibiotics. However, the following criteria must be met:

  • It must be confirmed with the bone biopsy that the origin of infection it is gram-negative m/o.
  • The organism must be sensitive to antibiotics.