INTRODUCTION

Osteomyelitis is an inflammatory condition affecting the bone and bone marrow, brought about by an infection ^1-3. Left untreated, this condition will result to the formation of dead, cortical bone associated with abscess formation, and surrounding bone formation; the sequestrum and involucrum ¹. Delay in presentation in children usually results in chronic osteomyelitis, requiring surgery and chemotherapy. Staphylococcus aureus is the most commonly isolated organism in these cases ⁴. However, the Methicillin-resistant strain (MRSA) now accounts for more than one-third of positive cultures ^4-6. Fibular osteomyelitis is relatively uncommon, with only a handful of cases reported in literature with only segmental involvement treated successfully with sequestrectomy and antibiotic therapy ^{2, 7-14}. Here we present a case of MRSA positive chronic osteomyelitis involving the entire diaphysis of the fibula and the subsequent treatment involving en bloc resection.

CASE REPORT

1. History and Physical Examination.

A 9-year old previously well, immunocompetent male presented at our institution with a seven month history of left leg pain and swelling after a fall from standing height. He was not brought for consult until persistence of pain and difficulty in ambulation. Consult was done at a local hospital, where he was diagnosed with cellulitis after normal radiographs, and was given Amoxicillin/Clavulanic acid for ten days with noted improvement of pain. Five months later, there was sudden recurrence of the swelling, progressively increasing in severity. Repeat laboratories revealed an elevated erythrocyte sedimentation rate (ESR), and he was again given Amoxicillin/Clavulanic acid for ten days, with complete resolution of swelling. Two weeks prior to consult, the symptoms returned, and on physical examination, the left leg (Fig. 1) was warm, non-erythematous, with generalized tenderness, but without pain on knee and ankle range of motion. Neurovascular status was normal, and infection and tumor workup returned with negative results, except for elevated alkaline phosphatase and ESR.

Fig. 1 (A, B and C)
Clinical picture of the patient, showing swelling of left lateral leg without any surrounding erythema or skin lesion. No sinus tracts.

2. Imaging

Radiographs of the left leg showed expansion and cortical thickening mixed with areas of lysis in the left fibular shaft, suggestive of chronic osteomyelitis (Fig. 2). Tubular, obliquely oriented lucencies in the mid and distal diaphyses were thought to represent sinus tracts and an oblique lucency noted in the proximal fibular shaft was suggestive of a pathologic fracture malunion, with irregular callus formation. MRI of the left leg showed non-union fracture at the proximal shaft of the left fibula, with marked periosteal thickening throughout the fibula, as well as intraosseous abscess, consistent with hematogenous osteomyelitis (Fig. 3).

Fig. 2a Anterior-posterior left leg radiograph of the patient
Fig. 2b Lateral left leg radiograph of the patient

 

Fig. 3 Left leg MRI showing hyperintensity representing bone marrow edema, as well as intraosseous abscess, characteristic of hematogeous osteomyelitis. There is a non-union fracture at the proximal shaft of the left fibula as well as marked periosteal thickening throughout the fibula