Hematogenous osteomyelitis in children: Clinical features and complications

INTRODUCTION — The clinical features and complications of hematogenous osteomyelitis in children will be discussed here. The epidemiology, microbiology, evaluation, diagnosis, and management of osteomyelitis in children are discussed separately:

●(See "Hematogenous osteomyelitis in children: Epidemiology, pathogenesis, and microbiology".)

●(See "Hematogenous osteomyelitis in children: Evaluation and diagnosis".)

●(See "Hematogenous osteomyelitis in children: Management".)

TERMINOLOGY — Osteomyelitis is an infection localized to bone. In children, osteomyelitis is usually caused by microorganisms (predominantly bacteria) that enter the bone hematogenously.

Pathogenic mechanisms for nonhematogenous osteomyelitis include direct inoculation (usually traumatic, but also surgical) and local invasion from a contiguous infection (eg, cellulitis, decubitus ulcer, sinusitis, periodontal disease). Risk factors for nonhematogenous osteomyelitis include open fractures that require surgical reduction, implanted orthopedic hardware (such as pins or screws), bite wounds, and puncture wounds. (See "Infectious complications of puncture wounds".)

CLINICAL FEATURES

Clinical presentation — The initial symptoms of hematogenous osteomyelitis can be nonspecific in children of all ages (eg, malaise, afebrile or low-grade fever). Once the infection becomes established in bone, symptoms usually are more localized; less commonly children present with septic shock and multifocal infection [1].

Clinical features by age group — The clinical features of osteomyelitis are influenced by the characteristics of the developing skeleton. (See "Hematogenous osteomyelitis in children: Epidemiology, pathogenesis, and microbiology", section on 'Pathogenesis'.)

Birth to three months — Osteomyelitis is rare in newborns and young infants, but the clinical features differ from those in older children, as described in retrospective studies from various countries and spanning five decades [2-7].

●At the time of presentation, the majority of neonates and young infants diagnosed with osteomyelitis are afebrile and have only mild symptoms such as vomiting or fussiness [2-4]. However, 77 to 100 percent have localized swelling and erythema and tenderness to palpation of a limb [3-7]. From 50 to 89 percent of infants have reduced movement or pseudoparalysis of the extremity [2-4,7]. The focality of these findings may cause clinicians to suspect conditions other than osteomyelitis (eg, cellulitis near prior venipuncture sites, extravasation of infusate, fractures). As the infection progresses, the epiphysis and adjacent joint may become involved. Soft tissue surrounding the infected bone may become swollen and discolored as purulent material ruptures through the thin bony cortex into the contiguous muscle bed. (See "Hematogenous osteomyelitis in children: Epidemiology, pathogenesis, and microbiology", section on 'Birth to three months'.)

A minority of neonates and young infants present with signs of sepsis or have a diagnosis of meningitis or other serious infection. Here, too, osteomyelitis may initially be overlooked.

●Radiographs provide evidence of osteomyelitis in 80 to 90 percent of infants at the time of evaluation of the focal clinical features [2,3,7,8]; in older children, radiographs are usually normal or inconclusive early in the course. Soft tissue swelling near the metaphysis, periosteal elevation, and lytic lesions are the most common abnormalities. Polyostotic disease has been reported in 18 to 47 percent of cases in neonates [2,5,7,9].

Given the frequency of polyostotic disease in neonates, osteomyelitis at more than one site or involvement of an adjacent joint must be suspected, regardless of the apparent severity of illness at the time of presentation. A skeletal survey may be warranted for all neonates. (See "Hematogenous osteomyelitis in children: Evaluation and diagnosis", section on 'Radiographs'.)

Children older than three months — Children older than 3 months of age with hematogenous osteomyelitis usually present acutely with fever, constitutional symptoms (eg, irritability, decreased appetite or activity), focal findings of bone inflammation (warmth, swelling, pain or point tenderness), and limitation of function (eg, limp, limited use of extremity) [1,10].

In a systematic review that included more than 12,000 children with acute and subacute osteomyelitis, presenting features included [11]:

●Pain – 81 percent

●Localized signs/symptoms – 70 percent

●Fever – 62 percent

●Reduced range of movement – 50 percent

●Reduced weight-bearing – 50 percent

●Older infants and toddlers – The initial symptoms of hematogenous osteomyelitis in older infants and young children frequently are nonspecific and mild. Verbal children may complain of localized pain. A history of nonspecific trauma may precede the onset of symptoms; diagnosis may be delayed if musculoskeletal complaints are initially attributed to trauma.

As the infection progresses, the child may refuse to use the affected extremity. Ambulatory young children with osteomyelitis of the lower extremity, pelvis, or spine may develop a progressive limp or refuse to sit, walk, or bear weight. Nonambulatory young children may refuse to sit or crawl, become irritable when picked up, or appear to be in pain or uncomfortable with diaper changing.

On examination, pain is typically well localized, with point tenderness over the infected bone; there may be contiguous edema. Pain is referred to the involved area when other parts of the long bone are percussed. In older infants and young children with vertebral osteomyelitis, there may be percussion tenderness over the contiguous spine, hip pain and stiffness, or loss of lumbar lordosis. However, it may be difficult to elicit these findings. Pelvic osteomyelitis may be localized to the buttock. In children with discitis, compression of the spine occasionally produces pain at the infected disc.

●Older children and adolescents – In late childhood and adolescence, patients are more likely than younger children to complain of localized pain. Injury, rather than infection, may be suspected initially, particularly if the child is without fever and systemic symptoms, and may delay the diagnosis of osteomyelitis.

On physical examination, the infectious process is more anatomically confined than in younger children. There is less swelling of the surrounding soft tissue and less functional restriction. The point tenderness is more circumscribed, though pain is still referred to the involved area when other parts of the long bone are percussed. In older children and adolescents with vertebral osteomyelitis, there may be percussion tenderness over the contiguous spine, hip pain and stiffness, or loss of lumbar lordosis.

Severe staphylococcal sepsis and venous thrombosis have been described in some adolescents with osteomyelitis [12,13] (see 'Complications' below). However, adolescents with subacute/chronic osteomyelitis may have developed a localized, sclerotic, intraosseous abscess (Brodie abscess (image 1)) and typically present with insidious onset of mild to moderate long bone pain, with or without fever [14].

Site of infection — Hematogenous osteomyelitis generally occurs at only one site [1,10]. However, multifocal infection may occur, particularly in critically ill neonates and children with disease caused by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) or Bartonella henselae, or in children with sickle cell disease [3,12,15-17].

Long (tubular) bones are affected more frequently than nontubular bones (ie, flat, irregular, and sesamoid bones) (figure 1). Infection in nontubular bones occurs most often in the calcaneus and pelvis [11]. (See 'Chronic hemodialysis' below and "Hematogenous osteomyelitis in children: Epidemiology, pathogenesis, and microbiology", section on 'Microbiology'.)

Long (tubular) bones — More than 80 percent of cases of hematogenous osteomyelitis occur in the long (tubular) bones, usually originating in the metaphyses [11,18]. The femur and tibia are most frequently involved (figure 1).

Because the long bones are affected in the majority of cases, the clinical features of long-bone osteomyelitis are the "classic" presentation: focal findings of bone inflammation (warmth, swelling, point tenderness) and limitation of function (eg, limp, limited use of extremity) [19]. (See 'Clinical presentation' above.)

Vertebral bodies and intervertebral discs — Infections of the spine can involve either the vertebral bodies or the intervertebral discs. Osteomyelitis of the spine should prompt consideration of Bartonella henselae and other unusual pathogens. (See 'Pathogen-specific features' below.)

●Vertebral bodies – The vertebrae are involved in approximately 4 percent of cases of osteomyelitis in children [11,20]. Patients usually are older than eight years. They seek medical attention because of dull, constant back pain. They may appear toxic and markedly febrile after an indolent course with low-grade fever for two weeks' to several months' duration. Examination findings of vertebral osteomyelitis may include exquisite tenderness with percussion of the spinal dorsal process, spasm of the paraspinous muscles around the involved vertebrae, and pain with flexion or extension of the spine.

In a retrospective case series of 14 children with vertebral osteomyelitis, the mean age was 7.5 years and the mean duration of symptoms was 33 days [20]. At the time of initial presentation, 8 of the 14 complained of back pain, and 11 were febrile.

Vertebral osteomyelitis is rare in newborns and is difficult to diagnose. Although some infants may be highly febrile and toxic-appearing, most have nonspecific symptoms and signs that are often overlooked, even in closely monitored settings such as neonatal intensive care units [21]. The infant may eventually develop irritability when moved or have signs of infection at another site. Given the indolent presentation, vertebral osteomyelitis in newborns may be complicated by paraspinal abscess or collapse of one or more vertebral bodies, with secondary kyphosis or paralysis [21-23]. (See 'Complications' below.)

●Intervertebral discs – Vertebral infections in children younger than five usually involve the intervertebral disc (discitis) rather than the vertebral body [20]. Discitis occurs almost exclusively in the lumbar regions. In young children, discitis typically presents with the gradual onset of irritability and back pain, limp, or refusal to crawl or walk, without systemic toxicity; fever usually is absent or low grade [20,24-26]. Abdominal pain and/or vomiting (secondary to ileus) may be the only complaints in children with involvement of T8 to L1. Most patients have had symptoms for three weeks or longer by the time discitis is diagnosed [20,24,27]. Examination findings may include percussion tenderness over the involved spine, hip pain and stiffness, loss of lumbar lordosis, neurologic findings (decreased muscle strength or reflexes), and ileus (with lesions of T8 to L1).

In a retrospective case series of 36 children with discitis, the mean age was 2.8 years and the mean duration of symptoms was 22 days [20]. At the time of presentation, 10 of the 36 were febrile, 23 of the 27 children <3 years of age had a limp or problems walking (eg, unsteady gait, refusal to walk, refusal to bear weight), and 6 of the 9 children ≥3 years of age complained of back pain.

Pelvis — Children with pelvic osteomyelitis often have symptoms referable to the hip, such as a gait abnormality or hip pain [28-30]. However, they also may localize the pain to the thigh, abdomen, lumbar spine, or buttocks. Fever is frequently absent. Osteomyelitis of the pelvis is generally caused by S. aureus and other gram-positive pathogens, but unusual organisms (including Salmonella species and B. henselae) should be considered [30,31]. (See 'Pathogen-specific features' below.)

Unlike children with septic arthritis of the hip, children with pelvic osteomyelitis usually allow passive range of motion of the hip (which may be decreased). However, pain may be elicited by simultaneously putting the hip in flexion, abduction, and external rotation (figure 2). In addition, careful palpation and rectal examination may reveal areas of point tenderness [31].

The clinical features of pelvic osteomyelitis were described in a case series of 64 children from a single institution [30]:

●The average age was 11.5 years (range 1.2 to 17.5 years)

●Presenting symptoms included pain (95 percent), fever (47 percent), and altered weight-bearing (48 percent)

●The average duration of complaints was 13 days

●Examination findings included tenderness in 66 percent, fever in 39 percent, and decreased range of motion at the hip in 43 percent

●White blood cell (WBC) count was >12,000/microL in 30 percent (average 15,800/microL) and erythrocyte sedimentation rate was increased in 88 percent (average 44 mm/h)

●The ilium was involved most frequently

Similar findings were reported in a smaller case series and literature review [29].

Pathogen-specific features — Compared with osteomyelitis cases in which an organism is not identified, culture-positive osteomyelitis is more frequently associated with a history of antecedent trauma; erythema, swelling, or frank cellulitis overlying the infected bone; a shorter duration of symptoms; and a higher WBC count [32,33].

The clinical features may vary depending upon the causative organism (table 1):

●S. aureus

•In neonates, S. aureus osteomyelitis frequently is associated with systemic symptoms and multifocal infection. In contrast, group B Streptococcus usually affects a single bone without a clinically evident preceding infection.

•Osteomyelitis caused by CA-MRSA is more severe than osteomyelitis caused by other pathogens (eg, increased height and duration of fever, greater elevation of inflammatory markers, increased risk of complications, increased need for surgical intervention) [12,13,34-37].

•Panton-Valentine leukocidin (PVL)-positive isolates of S. aureus are associated with severe localized reaction and systemic inflammatory response (eg, greater elevation of inflammatory markers, increased frequency of bone destruction, increased need for surgical intervention) [34-37]. The specific role of PVL in the pathogenesis of osteomyelitis remains unclear; it may be a surrogate for other virulence factors [38].

●Group A Streptococcus – Osteomyelitis caused by group A Streptococcus is associated with higher fever (38.9°C [102°F]) than methicillin-susceptible S. aureus (38.1°C [100.6°F]) or pneumococcus (38.2°C [100.8°F]) [11].

●Kingella kingae – K. kingae osteomyelitis generally affects children between 6 and 36 months of age and is typically milder and more indolent than osteomyelitis due to other pathogens. In one series of 43 children with K. kingae osteoarticular infections, only 15 percent of children were febrile at presentation, and 39 percent had normal inflammatory markers [39]. K. kingae may disproportionately affect nontubular bones (eg, sternum, vertebrae, calcaneum) [40].

●B. henselae – B. henselae is a well-documented cause of osteomyelitis of the axial skeleton (skull, vertebral bodies, ribs, and pelvis) after a cat scratch or bite (although contact with cats may not be specifically recalled in proven cases); it also may cause multifocal disease [17,41,42].

●Coccidioides – Coccidioidomycosis (an endemic mycosis due to Coccidioides immitis or Coccidioides posadasii) is a well-known cause of osteomyelitis in the southwestern United States; polyostotic disease is common, and the axial skeleton is frequently involved [43].

Special populations

Hemoglobinopathy — The clinical manifestations of hematogenous osteomyelitis in children with hemoglobinopathy (hemoglobin SS, S-beta thalassemia, hemoglobin SO-Arab, and certain children with hemoglobin SC) are similar to those in children without hemoglobinopathy. However, multiple sites may be involved, and it can be difficult to distinguish osteomyelitis from a vaso-occlusive pain [44,45]. (See 'Clinical features' above and "Overview of compound sickle cell syndromes" and "Acute and chronic bone complications of sickle cell disease", section on 'Osteomyelitis and septic arthritis'.)

Chronic granulomatous disease — The clinical manifestations of osteomyelitis in children with chronic granulomatous disease may be minimal, even with well-established destructive lesions. They also may have recurrent episodes of osteomyelitis caused by bacterial and fungal pathogens. (See "Chronic granulomatous disease: Pathogenesis, clinical manifestations, and diagnosis", section on 'Infections'.)

Chronic hemodialysis — Children undergoing chronic hemodialysis are at greater risk for hematogenous osteomyelitis because of repeated invasions of their vascular compartment [46]. Indwelling intravenous cannulas can be colonized with coagulase-negative staphylococci or S. aureus, and osteomyelitis may develop. The thoracic spine and ribs are the bones most commonly involved; other tubular and cuboidal bones that have been traumatized also can become infected.

Central venous catheters — Rare cases of osteomyelitis have been described in children with intestinal failure who are reliant upon indwelling central venous catheters and total parenteral nutrition. Osteomyelitis should be suspected when there are signs and symptoms of musculoskeletal infection [47].

LABORATORY FEATURES — The laboratory findings of children with osteomyelitis are described below. The laboratory evaluation for children with suspected osteomyelitis is discussed separately. (See "Hematogenous osteomyelitis in children: Evaluation and diagnosis", section on 'Initial evaluation'.)

●White blood cell count – Elevations in the peripheral white blood cell count (WBC) count in osteomyelitis are variable and nonspecific [48]. In a 2012 systematic review that included >12,000 patients, WBC count was elevated in only 36 percent of children at the time of presentation and normalized rapidly [11]. In a prospective study of 265 children with bone and joint infections (106 with osteomyelitis, 25 with osteomyelitis and septic arthritis), the mean WBC count was 12,600/microL at the time of presentation [49].

The WBC count tends to be higher and take longer to normalize in children with osteomyelitis caused by methicillin-resistant S. aureus (MRSA), group A Streptococcus, or Streptococcus pneumoniae and children with concomitant septic arthritis than in other clinical scenarios [50-54].

●Erythrocyte sedimentation rate – Elevation of the erythrocyte sedimentation rate (ESR) (≥20 mm/h) occurs in most children with osteomyelitis. In a 2012 systematic review, ESR was elevated in 91 percent of children at the time of presentation, peaked on day 3 to 5, and normalized over three to four weeks [11]. In a prospective study of 265 children with bone and joint infections (106 with osteomyelitis, 25 with osteomyelitis and septic arthritis), the mean ESR was 51 mm/h at the time of presentation [49].

The ESR tends to be higher and take longer to normalize in children with MRSA osteomyelitis and children with concomitant septic arthritis [50,51,55].

●C-reactive protein – Elevation of the C-reactive protein occurs in most children with osteomyelitis. In the 2012 systematic review, CRP was elevated in 81 percent of children at the time of presentation, peaked on day 2, and normalized over one week [11]. In a prospective study of 265 children with bone and joint infections (106 with osteomyelitis, 25 with osteomyelitis and septic arthritis), the mean CRP was 87 mg/L (8.7 mg/dL) at the time of presentation [49].

The CRP tends to be higher and take longer to normalize in children with MRSA osteomyelitis and children with concomitant septic arthritis [50,51,55-57].

RADIOGRAPHIC FEATURES — The radiographic features of osteomyelitis depend upon the imaging modality (table 2) [58]. Indications for specific imaging modalities in children being evaluated for osteomyelitis are discussed separately (table 3). (See "Hematogenous osteomyelitis in children: Evaluation and diagnosis".)

●Radiographs – Radiographic findings associated with osteomyelitis include deep soft tissue swelling (image 2), periosteal reaction (suggestive of new bone formation or reactive edema), periosteal elevation (suggestive of subperiosteal abscess) (image 3), and lytic sclerosis (suggestive of subacute/chronic infection) (image 4).

●Magnetic resonance imaging – Magnetic resonance imaging abnormalities of osteomyelitis are apparent earlier than radiographic abnormalities [59]. Areas of active inflammation show a decreased signal in T1-weighted images and an increased signal in T2-weighted images [60]. Fat-suppression sequences, including short tau inversion recovery, decrease the signal from fat and are more sensitive for the detection of bone marrow edema. The penumbra sign (high-intensity-signal transition zone between abscess and sclerotic bone marrow in T1-weighted images (image 5)) is characteristic of Brodie abscess [61].

●Scintigraphy – Focal uptake of tracer in the third phase of a three-phase bone scan is associated with osteomyelitis.

●Computed tomography – Computed tomography findings of osteomyelitis include increased density of bone marrow, cortex destruction, periosteal reaction (new bone formation), periosteal purulence, and sequestra.

●Ultrasonography – Ultrasonography findings compatible with osteomyelitis include fluid collection adjacent to the bone without intervening soft tissue, elevation of the periosteum by more than 2 mm, and thickening of the periosteum.

DIAGNOSIS — The evaluation and diagnostic approach to hematogenous osteomyelitis in children are discussed in detail separately. Diagnostic criteria are summarized below. (See "Hematogenous osteomyelitis in children: Evaluation and diagnosis".)

The diagnosis is confirmed by histopathologic evidence of inflammation in a surgical specimen of bone (picture 1A-C) (if obtained) or identification of a pathogen by culture or Gram stain in an aspirate or biopsy of bone, or a periosteal fluid collection [18].

The diagnosis is probable in a child with compatible clinical, laboratory, and/or radiologic findings (table 2) in whom a pathogen is isolated from blood or joint fluid or, if cultures are negative, detection of S. aureus, S. pyogenes, S. pneumoniae, or K. kingae by polymerase chain reaction (PCR) in bone aspirates, subperiosteal collections, or synovial fluid. We also consider the diagnosis to be probable in a child with compatible clinical, laboratory, and radiologic findings and negative cultures and PCR if they respond as expected to empiric antimicrobial therapy.

The diagnosis is unlikely if advanced imaging studies (usually magnetic resonance imaging or scintigraphy) are normal throughout the course of evaluation.

COMPLICATIONS

Musculoskeletal — Musculoskeletal complications of osteomyelitis vary with age, site of involvement, pathogen, and duration of infection. In a review of 286 children with osteoarticular infections (160 with osteomyelitis and 96 with osteomyelitis and septic arthritis) from a single institution, musculoskeletal complications occurred in 9 percent and were independently associated with fever (>38°C [100.4°F]) >4 days after admission, delayed source control, and agr group III S. aureus [62].

Musculoskeletal complications include [17,21-23,62-67]:

●Acute complications include:

•Extension of infection into the soft tissue (eg, pyomyositis), common in young infants.

•Septic arthritis if infection spreads to the joint space (more common with infections of the proximal humerus and femur) or with hematogenous delivery of organisms to the joint space (image 6).

•Subperiosteal abscess (image 3).

•Brodie abscess (image 1).

•Multifocal infection (more common with community-acquired methicillin-resistant S. aureus [CA-MRSA] or B. henselae and in newborns).

●Chronic complications include:

•Pathologic fracture (more common with CA-MRSA) [68].

•Osteonecrosis (avascular necrosis) of the femoral head.

•Collapse or complete destruction of one or more vertebral bodies, which may be associated with kyphosis or spinal cord compression.

•Devitalized bone (sequestra) and cutaneous fistulae.

•Abnormal bone growth (angular deformity, shortening (image 7A), or overgrowth (image 7B)) with involvement of the physis and epiphysis (more common in newborns and CA-MRSA infections).

•Chronic osteomyelitis (radiographic evidence of devitalized bone and ≥2 weeks of signs and symptoms of bone inflammation) occasionally occurs in a child who has longstanding musculoskeletal complaints that are not recognized as osteomyelitis [69]. However, it is usually described in patients with inadequate duration of therapy. (See "Hematogenous osteomyelitis in children: Management", section on 'Chronic osteomyelitis'.)

Chronic complications are associated with C-reactive protein (CRP) >100 mg/dL two to four days after starting antibiotics, disseminated disease, and bone debridement [70,71].

Venous thrombosis — Venous thrombosis and septic emboli may occur in older children and adolescents with osteomyelitis (image 8) [13,72-75]. Although the pathogenesis is uncertain, small observational studies suggest that venous thrombosis and septic emboli in children with osteomyelitis are associated with [13,72,74-76]:

●Age ≥8 years

●Occurrence at sites adjacent to the osteomyelitis

●S. aureus osteomyelitis, particularly MRSA and Panton-Valentine leukocidin-positive strains

●Coagulation abnormalities (eg, heterozygous for factor V Leiden mutation, increased antiphospholipid antibodies or factor VIII concentrations, positive lupus anticoagulant), some of which were transient

●Disseminated infection

●CRP >60 mg/L (6 mg/dL) at presentation

●Increased severity of infection (eg, longer hospitalization, more surgical procedures)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Septic arthritis and osteomyelitis in children".)

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Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Osteomyelitis in children (The Basics)")

SUMMARY

●Clinical presentation – The initial symptoms of osteomyelitis can be nonspecific (eg, malaise, low-grade fever) in children of all ages. Once the infection becomes established in bone, symptoms are more localized. Children with osteomyelitis usually present with fever, constitutional symptoms (irritability, decreased appetite, decreased activity), focal findings of bone inflammation (warmth, swelling, point tenderness), and limitation of function (eg, limp, limited use of extremity). (See 'Clinical presentation' above.)

●Clinical features by age group – Clinical features may vary with age:

•In young infants (zero to three months of age), initial clinical features may be mild and nonspecific. Bone infection may spread to the adjacent soft tissues and joints. (See 'Birth to three months' above.)

•In older infants and young children, clinical features may include limp; refusal to crawl, walk, sit, or bear weight; irritability when picked up; point tenderness over the infected bone; and contiguous edema. (See 'Children older than three months' above.)

•In older children and adolescents, clinical features may include complaints of localized pain and focal examination findings (point tenderness). (See 'Children older than three months' above.)

●Clinical features by site of infection

•Children with osteomyelitis of the vertebral bodies usually are older than eight years and complain of dull, constant back pain. Examination findings may include tenderness with percussion of the spinal dorsal process, spasm of the paraspinous muscles around the involved vertebrae, and pain with flexion or extension of the spine. (See 'Vertebral bodies and intervertebral discs' above.)

•Discitis is more common in children younger than five years and usually occurs in the lumbar regions. Clinical features include gradual onset of irritability and back pain, limp, or refusal to crawl or walk, without systemic toxicity. Examination findings may include percussion tenderness over the involved spine, hip pain and stiffness, loss of lumbar lordosis, neurologic findings (decreased muscle strength or reflexes), and ileus (with lesions of T8 to L1). (See 'Vertebral bodies and intervertebral discs' above.)

•Children with pelvic osteomyelitis may complain of hip pain or gait abnormality, but also may localize pain to the thigh, abdomen, lumbar spine, or buttocks. Examination findings may include point tenderness and pain when the hip is simultaneously flexed, abducted, and externally rotated. (See 'Pelvis' above.)

●Laboratory features and radiographic features

•Laboratory features of osteomyelitis include elevations in erythrocyte sedimentation rate and C-reactive protein. Most patients do not have an elevated peripheral white blood cell count at the time of presentation. (See 'Laboratory features' above.)

•Radiographic features of osteomyelitis depend upon the imaging modality (table 2). (See 'Radiographic features' above.)

●Complications – Complications of osteomyelitis include extension of infection into the soft tissues, septic arthritis, abnormal bone growth (image 7A-B), subperiosteal or intraosseous abscess, pathologic fracture, devitalized bone, chronic osteomyelitis, and venous thrombosis. (See 'Complications' above.)

●Evaluation and diagnosis – The evaluation and diagnosis of hematogenous osteomyelitis in children are discussed separately. (See "Hematogenous osteomyelitis in children: Evaluation and diagnosis".)