Epiphyseal osteomyelitis was rarely seen, though reports were gradually increasing in recent years. Conventional view held that epiphyseal osteomyelitis was more common in infants for blood vessels supplying the epiphysis and metaphysis were interconnected in infants [6]. Along with the bone development, formation of the epiphysis plate prevents inflammation from invading the epiphysis in children. However, in this study, age at onset of epiphyseal osteomyelitis was between 1 and 12 years, suggested a prevalence of epiphyseal osteomyelitis in children rather than limited in infants, consistent with Ceroni’s finding [7]. It was reported that males were twice more susceptible to acute osteomyelitis than females [8]. Among the 32 osteomyelitis patients in Gilbertson-Dahdal’s study, 86% of males were suffered epiphysis plate damage, with a ratio of 73% in females [9]. Though without difference in statistical analysis, the differences showed a propensity that gender might also be a risk factor of epiphyseal osteomyelitis in children. Male-female ratio in this study was 20:11 in control group, consistent with previous study [8]. However, the ratio of 5:7 in observation group might resulted from bias due to the small number of cases included.
In Ceroni’s study, 88% of primary epiphyseal osteomyelitis occurred in the femur and tibia [7]. Of the 32 secondary epiphyseal osteomyelitis patients in Gilbertson-Dahdal’s study, 13 located in proximal tibia and 8 in distal femur [9]. The most common sites of epiphyseal osteomyelitis and metaphyseal osteomyelitis were distal femur and proximal tibia in this study, consistent with previous studies [7, 9]. To analyze the reason of frequency of epiphyseal osteomyelitis in femur and tibia. On one hand, metaphyseal was a common location of osteomyelitis involvement, secondary epiphysis plate damage might lead to epiphyseal osteomyelitis. On the other hand, the larger epiphysis of the distal femur and proximal tibia then other site was more likely to get infected. Meanwhile, symptoms of osteomyelitis in somewhere with smaller epiphysis was too mild to be recognized might lead to a bias of predisposing infection area [7].
Staphylococcus aureus was the most common pathogen of primary epiphyseal osteomyelitis and metaphyseal osteomyelitis [10], Salmonella and Mycobacterium infections were also reported [4, 11]. Secondary epiphyseal osteomyelitis shared the same pathogen with metaphyseal osteomyelitis for directly epiphysis plate damage. In Gilbertson-Dahdal’s study, percentage of infections that penetrate epiphyseal plates of all in each group was 63% in MSSA infection, and 100% in MRSA infection [9]. In observation group of the present study, the ratio of MRSA infection patients was significantly higher than that of MSSA group (p < 0.050). It was inferred that MRSA may be more aggressive, promoting the damage to the epiphyseal plate and the localized spread of infection.
Inflammatory indexes such as blood cell count and classification, C-reactive protein, and ESR were commonly used to detect bacterial infection, however the role of procalcitonin in bone and joint infection is unclear and was not recommended [12]. It was reported that about 1/3 of children with osteomyelitis have abnormal white blood cell count, However, the sensitivity and specificity of this parameter are limited, especially in young children [13–14]. ESR was with a higher sensitivity, especially in patients with abscesses or septic arthritis. ESR over 55mm/h indicated local abscess formation [15]. Pääkkönen reported a sensitivity of 95% of C-reactive protein, 94% of ESR, and 98% of combination of both as markers of distinguish osteomyelitis from suppurative arthritis [16]. Nearly all patients were with elevated C-reactive protein and ESR, and the average ESR was over 55mm/h of all, indicating abscess formation. Though without statistical difference, levels of C-reactive protein (116.45 ± 66.02 mg/L VS 93.05 ± 60.29 mg/L, p = 0.275)and ESR ༈76.17 ± 28.26 mm/h VS 61.48 ± 24.43 mm/h, p = 0.098༉in observation group were higher than that in control group.
Antibiotic combined with surgical operation was the first-line treatment for epiphyseal osteomyelitis [3, 5,]. First- or second- generation cephalosporin antibiotics was applied as a preferred empirical medication on admission, for Staphylococcus aureus was the most common pathogen. Treatment was adjusted according to drug sensitivity of pus culture. As to the timing of surgery, Sun KM recommended surgical treatment should be performed immediately after the diagnosis was confirmed for early extraction of pus samples, drainage and decompression [17]. He MZ compared treatment of infantile epiphysis osteomyelitis among antibiotics alone, joint irrigation and drainage alone, and joint incision and drainage combined with drilling of epiphysis and metaphysis, with the finding that the third method presented obvious advantages in shortening hospital stay, reducing disability rates, and improving quality of life of patients [18]. All patients underwent fenestration of metaphyseal cortex under intravenous inhalation combined with general anesthesia, with satisfactory short-term therapeutic effect. However, the long-term complications of epiphysis osteomyelitis included epiphysis avascular necrosis, limb length difference, and angular deformity. Long-term follow-up was required until mature of the epiphysis [19].