Osteomyelitis in Diabetic Foot Ulcers: the Malaysian Experience
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Clinical practice Osteomyelitis in diabetic foot ulcers: the Malaysian experience Osteomyelitis is defined as an inflammation of the bone marrow. Approximately 20% of patients with diabetes will develop osteomyelitis and it is linked to high rates of mortality, morbidity and amputation. Diagnosing osteomyelitis associated with a diabetic foot can be challenging as it is difficult to identify the infection in its initial phase and there is often Authors: symptom and clinical manifestation variability. As there are no standardised Harikrishna KR Nair, Sylvia SY Chong tests or criteria for diagnosing osteomyelitis, it may be helpful to obtain a patient’s complete history of symptoms, including physiological state (risk factors) with clinical manifestation, laboratory tests, imaging and blood or bone cultures to come to a final diagnosis. This article looks at some of the tests that can be used in the diagnosis process. he importance of wound irrigation and As seen below, Lew and Waldvogel (Figure 1) cleansing solutions is often ignored, with Cierny and Mader are two major clinical TWAs Malhotra et al (2014) have shown, classifications for osteomyelitis. According to osteomyelitis is defined as an inflammation Lew and Waldvogel in 1970, osteomyelitis is of the bone marrow. A bacterial infection can classified based (Table 1) on the length of cause inflammation of the bone tissue, which evolution and pathophysiology. can result in inflammatory destruction, necrosis, Cierny and Mader (1984) attempted to bone neoformation, and it can progress into a address some aspects that were not covered chronic or persistent stage (Smith et al, 2006). by Lew and Walvogel’s classification . They Staphylococcus aureus is the most common classified osteomyelitis by anatomical stages pathogenic organism isolated in osteomyelitis, according to bone infection and the type of although a variety of organisms can cause this host health status, depending on the patient’s disease, as outlined by Lew and Woldvogel (2015). clinical conditions (Table 2). Harikrishna KR Nair is Head of Wound Care Unit, Department of Internal Medicine, Hospital Kuala Lumpur; Sylvia SY Chong is a Research Assistant, Wound Care Unit, Department Figure 1. Lew and Waldvogel with Cierny and Mader are two major clinical classifications of Internal for osteomyelitis Wounds Asia 2021 | Vol 4 Issue 1 | ©Wounds Asia 2021 | www.woundsasia.com 19 Clinical practice Table 1. The Lew and Waldvogel osteomyelitis classification system Duration of infection Description Acute Initial episodes of osteomyelitis with the presence of oedema, pus formation, vascular congestion and thrombosis of the small vessels Chronic Recurrence of acute cases with large areas of ischemia, necrosis and bone sequestra Mechanism of bone infection Description Hematogenous Commonly seen in children and occurs through secondary infection when bacterial is transported through the blood Contiguous Bacterial inoculation from an adjacent focus, e.g. post-traumatic osteomyelitis, or infections related to prosthetic devices Associated with vascular insufficiency Infections affecting the feet in patients with diabetes, hanseniasis or peripheral vascular insufficiency Table 2. The Cierny and Mader osteomyelitis classification system Anatomical stage Description 1 Medullary Infection restricted to the bone marrow 2 Superficial Infection restricted to cortical bone 3 Localised Infection with clearly defined edges and bone stability preserved 4 Diffuse Infection spread to the entire bone circumference, with stability before or after debridement Host health status Description A Host healthy Patients without comorbidities Bl Local Smoking, chronic lymphedema, venous stasis, arthritis, large scars, fibrosis compromise by radiotherapy Bs Systemic Diabetes mellitus, malnutrition, renal or hepatic failure, chronic hypoxia, compromise neoplasms, extremes of age C Poor clinical Surgical treatment will have a higher risk than the osteomyelitis itself conditions Hematogenous osteomyelitis is most are Staphylococcus aureus (Asmar, 1992). As commonly seen in infants and children, and reported by Ramsey et al (1999) and Lavery et usually involves the metaphysis of long bones, al (2009), about 20% of osteomyelitis cases are particularly the femur and tibia. Metaphyseal acute hematogenous osteomyelitis. Of these, spongiosa contains abundant blood vessels children under the age of 5 account for 50%. with leaky endothelium and a sluggish flow This accumulates up to 85% for cases involving that ends in capillary loops and provides a children under the age of 17, as stated by suitable environment for bacteria growth, Cierny and Mader (1984). as reported by Whyte and Bielski (2016). In The most common infection site is the children under the age of one, there have vertebrae, but it can also occur in the pelvis, been cases of osteomyelitis affecting the clavicle and long bones, and, as reported by epiphysis due to the connection of blood Arciola et al (2005), only 2–7% of adults have vessels passing through the metaphysis to this condition. As Rao et al (2011) have shown, the epiphysis. As shown by McPherson (2002), hematogenous osteomyelitis is usually an acute Liao et al (2005), and Qadir et al (2010), in disorder and primarily treated conservatively. new-borns the most common pathogens are On the other hand, as stated by Lew and Streptococcus agalactiae, Escherichia coli and Waldvogel in 1970, chronic osteomyelitis is Klebsiella pneumonia, while in children the characterised by progressive reoccurrence or common pathogens across all age groups multiple episodes of acute osteomyelitis at the 20 Wounds Asia 2021 | Vol 4 Issue 1 | ©Wounds Asia 2021 | www.woundsasia.com Figure 2. X Rays with bony erosions, subluxations, soft tissue swellings etc and pictures of the wounds with bone exposed or probe test positive with osteomyelitis are shown in a–c a. Patients with osteomyelitis and chronic wounds currently undergoing treatment under the Wound Care Unit, Hospital Kuala Lumpur b. Patients with osteomyelitis and chronic wounds currently undergoing treatment under the Wound Care Unit, Hospital Kuala Lumpur c. Patients with osteomyelitis and chronic wounds currently undergoing treatment under the Wound Care Unit, Hospital Kuala Lumpur same site, which can lead to bone necrosis (Lew in patients with diabetes, as stated by Sia and and Waldvogel, 2004). Berbari (2006). In elective trauma surgery, Other entry routes of infection are secondary close fractures and first- to third-degree open to the direct inoculation of bacteria into fractures had 1–5% and 3–50% of contagious the bone tissue. The can occur in acute infection respectively, as reported by Gustilo trauma (an open fracture) and surgery (with et al (1990). As Parvazi et al (2008) have shown, or without implantation), as well as poor early infections are expected in 0.5% to 2% peripheral vascular supply with infection of of primary hip and knee replacement cases, the surrounding tissues. This is especially seen and more than 20% of septic revisions and Wounds Asia 2021 | Vol 4 Issue 1 | ©Wounds Asia 2021 | www.woundsasia.com 21 CaseClinical reports practice 5% of aseptic revisions have deep infections. clinical manifestation variability. As Arias et Generally, infectious complications occur in al (2019) have shown, because there are no 5% of traumatic and orthopaedic implants standardised tests or criteria for diagnosing during the lifetime of the implant (Trampuz and osteomyelitis, it may be helpful to see a patient’s Zimmerli, 2006). complete history of symptoms, including Contiguous spread of pathogens from physiological state (risk factors) with clinical infected diabetic foot ulcers (DFU) to the manifestation, laboratory tests, imaging, and bone is the pathogenesis of osteomyelitis blood or bone cultures to come to a final in a diabetic foot. Bacteria induce an acute diagnosis. Furthermore, patients with diabetes inflammatory reaction during infection of the and peripheral neuropathy are also prone to bone and the bacteria and inflammation affect developing Charcot neuro-osteoarthropathy, the periosteum and spread in the bone, causing which closely resembles and may co-exist with bone necrosis. Lifting of the periosteum further diabetic foot-associated osteomyelitis (Berendt impairs the blood supply to the affected bone, et al, 2008). causing segmental bone necrosis known as a Clinical suspicion is very important when sequestrum. In the chronic stage, numerous commencing a medical investigation for inflammatory cells and their release of cytokines osteomyelitis. A thorough assessment of the stimulate osteoclastic bone resorption, foot or lower extremity should be performed, ingrowth of fibrous tissue, and the deposition including examination of the ulcer, presence of of reactive new bone in the periphery. When peripheral neuropathy (present in 88% of DFUs), the newly deposited bone forms a sleeve of peripheral vascular disease (present in 45–65% living tissue around the segment of devitalised of DFUs), and the extent of any underlying infected bone, it is known as an involucrum. infection (Nair, 2017). Infected DFUs usually As Rosenberg (2010) has shown, a rupture of have purulent secretions or at least two signs of a subperiosteal abscess may lead to a soft- inflammation, as stated by Giurato et al (2017) tissue abscess and the eventual formation of a and Jeffcoate and Lipsky (2004), yet diabetic draining sinus. foot-associated osteomyelitis can occur without As reported in several publications