One of significant challenges faced by diabetologists, surgeons and orthopedists who care for patients with diabetic foot syndrome is early diagnosis and differentiation of bone structure abnormalities typical of these patients, i.e. osteitis and Charcot arthropathy. In addition to clinical examination, the patient's medical history and laboratory tests, imaging plays a significant role. The evaluation usually begins with conventional radiographs. In the case of osteomyelitis, radiography shows osteopenia, lytic lesions, cortical destruction, periosteal reactions as well as, in the chronic phase, osteosclerosis and sequestra. Neurogenic arthropathy, however, presents an image resembling rapidly progressing osteoarthritis combined with aseptic necrosis or inflammation. The image includes: bone destruction with subluxations and dislocations as well as pathological fractures that lead to the presence of bone debris, osteopenia and, in the later phase, osteosclerosis, joint space narrowing, periosteal reactions, grotesque osteophytes and bone ankylosis. In the case of an unfavorable course of the disease and improper or delayed treatment, progression of these changes may lead to significant foot deformity that might resemble a "bag of bones". Unfortunately, radiography is non-specific and frequently does not warrant an unambiguous diagnosis, particularly in the initial phase preceding bone destruction. For these reasons, alternative imaging methods, such as magnetic resonance tomography, scintigraphy, computed tomography and ultrasonography, are also indicated.

Surgical correction of complex foot and ankle deformities secondary to Charcot neuroarthropathy remains a significant surgical challenge. New technological advancements in hardware have allowed for the use of augmented fixation techniques in midfoot deformity correction, including the use of indication-specific locking plates and beaming techniques that offer enhanced stability. Severe hindfoot deformity management can employ the use of internal fixation, including intramedullary hindfoot nails and circular external fixation frames for limb salvage.

Charcot deformity is a challenge that foot and ankle surgeons struggle to manage successfully. Despite the advances in knowledge, technology, and treatment modalities, limb loss is still greater than 10%. This article discusses the efficacy of conservative measures and traditional surgical approaches. It proposes a multidisciplinary team approach, medical optimization, and lifestyle modification to put the patient in the best position to heal. Also discussed is the authors' staged surgical treatment protocol to enhance outcomes and decrease the rate of limb loss.

Osteomyelitis is inflammation of the bone caused by an infectious organism, and is a difficult clinical problem. The pathophysiology, imaging, and classification of osteomyelitis are challenging, varying with the age of the patient (child versus adult), the chronicity of the infection (acute versus chronic), and the route of spread (hematogenous versus contiguous focus), as well as the immune and vascular status of the patient and affected region. The two most common classification schemes are those of Lew and Waldvogel, and Cierny and Mader. Brodie's abscess is seen in subacute osteomyelitis, while sequestrum, involucrum, and cloaca are inter-related entities of chronic osteomyelitis. Imaging workup of suspected osteomyelitis should begin with radiographs, although MRI is the most accurate imaging test. Three patterns of T1 signal change have been described in the setting of suspected osteomyelitis including confluent intramedullary, hazy reticular, and subcortical. The confluent intramedullary pattern is most associated with osteomyelitis, while hazy reticular is rarely associated with hematogenous osteomyelitis, and subcortical is not associated with osteomyelitis. It can be challenging to differentiate neuropathic arthropathy from osteomyelitis. Osteomyelitis tends to involve a single bone subjacent to an ulcer or sinus tract. In contrast, neuropathic arthropathy tends to involve multiple bones of the midfoot. Subchondral cystic change, thin rim enhancement of a joint effusion, and the presence of intra-articular bodies are more indicative of a neuropathic joint without infection. Biopsy can play an important role in diagnosis and treatment of osteomyelitis.

Diabetic neuropathic osteoarthropathy (DNOAP) is an uncommon, but with considerable morbidity and mortality rates, complication of diabetes. The real pathogenesis is still unclear. The two popular theories are the neuro-vascular theory and neuro-traumatic theory. Most theories and pathways focused on the uncontrolled inflammations that resulted in the final common pathway, receptor activator of nuclear factor κβ ligand (RANKL)/osteoprotegerin (OPG) axis, for the decreased bone density in DNOAP with an osteoclast and osteoblast imbalance. However, the RANKL/OPG pathway does not explain all the changes, other pathways and factors also play roles. A lot of DNOAP potential relative risk factors were evaluated and reported in the literature, including age, gender, weight, duration and type of diabetes, bone mineral density, peripheral neuropathy and arterial disease, trauma history, and some others. However, most of them are still in debates. Future studies focus on the pathogenesis of DNOAP are still needed, especially for the genetic factors. And, the relationship between DNOAP and those potential relative risk factors are still need to further clarify.

Charcot neuroarthropathy of the foot, or Charcot foot, is a pathologic entity of the foot, associated with diabetes mellitus. Owing to the increase of diabetes mellitus in developed nations worldwide, the prevalence of Charcot foot has been increasing. The initial treatment of Charcot foot is often conservative, with methods including bracing, casting, and the use of customized orthopedic shoes. However, many cases of Charcot foot eventually require surgery, because the consequent destabilization of the foot associated with bone, joint, and nerve injury due to the pathology eventually leave patients unable to walk independently. The present systematic review analyzed the published data regarding surgical interventions for midfoot Charcot deformities and estimated the rates of common complications occurring with the surgical modalities studied. The main outcomes of interest analyzed in the present study were postoperative amputation and bony fusion. The included cohort of patients with Charcot foot was very heterogeneous in terms of the demographic and comorbid characteristics. However, even with this heterogeneity, the present study should provide useful information to surgeons in terms of the outcomes after some of the common surgical procedures for midfoot Charcot.