The diabetic foot

Foot complications in diabetics often lead to amputation. Ulceration is the most common complication in the diabetic forefoot and underlies more than 90% of cases of pedal osteomyelitis. The diagnosis of osteomyelitis is, nevertheless, difficult, and imaging is an important part of the work-up. Plain radiographs, although useful for anatomical information, are neither sensitive nor specific. Three-phase bone scintigraphy is sensitive but not specific. Labelled leucocyte scintigraphy and MRI are both useful and are complementary to one another. Labelled leucocyte scintigraphy is valuable for diagnosis as well as follow-up of pedal osteomyelitis. MRI offers exquisite anatomical detail, which is invaluable for guiding surgical management. The principal complication in the mid and hind foot is the neuropathic or Charcot joint. Although infection of the neuropathic joint is infrequent, its diagnosis is difficult. The extensive bony changes that accompany this disorder severely diminish the value of radiography and bone scintigraphy. It is not always possible to distinguish the marrow oedema of neuropathy from that of osteomyelitis and the role of MRI in the evaluation of this entity is still uncertain. Uptake of labelled leucocytes in the absence of infection may occur and is owing, at least in part, to haematopoietically active marrow. Combined leucocyte/marrow scintigraphy holds considerable promise for identifying the infected Charcot joint.     

Subchondral bone and cartilage disease: a rediscovered functional unit

The role of subchondral bone in the pathogenesis of cartilage damage has likely been underestimated. Subchondral bone is not only an important shock absorber, but it may also be important for cartilage metabolism. Contrary to many drawings and published reports, the subchondral region is highly vascularized and vulnerable. Its terminal vessels have, in part, direct contact with the deepest hyaline cartilage layer. The perfusion of these vessels accounts for more than 50% of the glucose, oxygen, and water requirements of cartilage. Bony structure, local metabolism, hemodynamics, and vascularization of the subchondral region differ within a single joint and from one joint to another. Owing to these differences, repetitive, chronic overloading or perfusion abnormalities may result in no pathological reaction at all in one joint, while in another joint, these same conditions may lead to osteonecrosis, osteochondritis dissecans, or degenerative changes. According to this common etiological root, similar pathological reactions beginning with marrow edema and necrosis and followed by bone and cartilage fractures, joint deformity, and insufficient healing processes are found in osteonecrosis, osteochondritis dissecans, and degenerative disease as well.     

Manubriosternal joint: imaging features of normal anatomy and arthritis

Normal findings of the manubriosternal joint vary and include narrowing, irregularity, and ankylosis. Proliferative changes are common during the degenerative process, and they include osteophyte formation and sclerosis. Ankylosis may be an end result. Imaging features of inflammatory arthritides are also generally nonspecific. Bone marrow and adjacent soft tissue change on magnetic resonance imaging with no radiographic findings is a relatively early change. Only erosion and fluffy adjacent bone resorption on plain radiography and computed tomography are specific features of active arthritis.     

Osteitis deformans of the hip joint.

It is estimated that 66% of patients with Paget's disease have involvement of the pelvis and 46% of the proximal femur. Therefore, it is not unexpected that hip pain is one of the major presenting complaints. Analysis of the radiographs of 25 hips with one or more articular sufaces involved by Paget's disease demonstrated narrowing in 24. Unlike the findings in primary degenerative joint disease, the majority of cases had a radiographic pattern characterized by uniform narrowing of the articular cartilage and minimal hypertrophic changes. Pathologic correlation was obtained from specimens of four patients who underwent total hip replacements. The pathogenesis of arthritic changes associated with osteitis deformans is not established. The evidence presented suggest that cartilagenous narrowing results from a disturbance in endochondral bone formation related to the hyperemia of Paget's disease. Secondary deformities of bone produce further derangement of joint mechanics. The secondary degenerative changes which ensue differ mechanically, and therefore radiographically, from primary degenerative joint disease.     

Bone and soft tissue abnormalities of the upper extremity in diabetes mellitus.

Roentgenographic evidence of bone and soft tissue abnormalities may be noted in the upper extremities of diabetics. Major shoulder changes, typically associated with peripheral neuropathy, include humeral head deformity due to bone resorption, joint space narrowing, subchondral cysts and sclerosis, subluxation, and juxtra-articular soft tissue bone fragments. Charcot-type joints, characterized by severe joint destruction, sclerosis, multiple bone fragments, and soft tissue swelling may occur. Diabetic neuropathy can produce flexion contractures of the hand. Abnormalities not necessarily associated with clinical neuropathy include cystic bone changes, cortical bone erosions, soft tissue calcification (calcific tendinitis), and vascular calcification.     

Spinal neuroarthropathy after traumatic paraplegia

Spinal neuroarthropathy is a little-known complication of traumatic paraplegia. Four cases of this syndrome are described, with emphasis on the characteristic radiographic findings of severe juxta-articular bone destruction, dense appositional new bone formation, large osteophytosis, and soft-tissue bony debris. The factors predisposing patients to develop a neuropathic joint are diminished pain and proprioceptive sensations with maintained mobility. When a paraplegic patient transfers in or out of a wheelchair or moves his upper torso, he exerts force on an insensate spine. Repeated trauma increases joint mobility beyond the normal limits, and this leads to further damage, with the process culminating in severe instability and bone destruction. The other causes of neuropathic joints in the spine--tertiary syphilis, syringomyelia, and diabetes--must be ruled out on clinical grounds. Neuropathic changes in the spine are often silent, delaying treatment, or may be mistaken for infection or degenerative disease. Their true prevalence is difficult to determine, but the possibility should be considered in paraplegic patients with the characteristic radiographic findings.     

Radionuclide bone imaging: an illustrative review.

Bone scintigraphy with technetium-99m-labeled diphosphonates is one of the most frequently performed of all radionuclide procedures. Radionuclide bone imaging is not specific, but its excellent sensitivity makes it useful in screening for many pathologic conditions. Moreover, some conditions that are not clearly depicted on anatomic images can be diagnosed with bone scintigraphy. Bone metastases usually appear as multiple foci of increased activity, although they occasionally manifest as areas of decreased uptake. Traumatic processes can often be detected, even when radiographic findings are negative. Most fractures are scintigraphically detectable within 24 hours, although in elderly patients with osteopenia, further imaging at a later time is sometimes indicated. Athletic individuals are prone to musculoskeletal trauma, and radionuclide bone imaging is useful for identifying pathologic conditions such as plantar fasciitis, stress fractures, "shin splints," and spondylolysis, for which radiographs may be nondiagnostic. A combination of focal hyperperfusion, focal hyperemia, and focally increased bone uptake is virtually diagnostic for osteomyelitis in patients with nonviolated bone. Bone scintigraphy is also useful for evaluating disease extent in Paget disease and for localizing avascular necrosis in patients with negative radiographs. Radionuclide bone imaging will likely remain a popular and important imaging modality for years to come.     

Imaging of neuropathic arthropathy

Neuropathic arthropathy is a chronic, progressive joint degeneration with bone fragmentation, ligamentous instability, and dislocation. Diabetes is the leading cause of neuropathic arthropathy. Conventional radiography is the most commonly used imaging modality for diagnosing neuropathic arthropathy. The disease is mostly the hypertrophic type and is manifested by sclerosis of the bone, fragmentation, joint destruction, swelling, large joint effusion, and large osteophyte formation. Computed tomography, magnetic resonance imaging and radionucleide scintigraphy are helpful for diagnosing the disease and may help in distinguishing neuropathic arthropathy from septic arthritis and osteomyelitis.     

Radiological appearances following limb replantation: a report of 5 cases

Plain radiographs of the limbs were reviewed after replantation procedures following traumatic amputation in 5 patients at the wrist (2), mid-forearm (2) and knee (1). Following upper limb replantation, rapid development of osteopaenia was initially noted in the juxta-articular regions and metaphyses of the tubular bones of the hand. These changes were followed by diaphyseal cortical bone loss with evidence of subperiosteal, intracortical and endosteal bone resorption. Juxta-articular erosions developed at the margins of the small joints in the hand in all cases. Gradual resolution of bone changes was noted in 3 of the 4 cases where follow-up exceeded 5 years. Following lower limb replantation, there was no evidence of bone loss; however, severe neuropathic joint disease developed within 18 months and progressed over the following 9 years. We suggest that the radiographic changes observed after upper limb replantation reflect regional hyperaemia secondary to neurovascular damage, whilst the changes in the lower limb reflect a similar process in a limb subjected to weight bearing. Address reprint requests to: Department of Diagnostic Radiology, The Medical School, Stopford Building, University of Manchester, Oxford Rd, Manchester, M13 9PT, UK     

The pathology of total joint arthroplasty

Although the clinical results of total joint arthroplasty are usually excellent, some implants develop loosening and require revision. Implants usually fail by a combination of mechanisms, but different basic designs tend to show different dominant mechanisms of failure. Infection causes failure of about 1–5% of cases of primary arthroplasty. Clues to the presence of infection include clinical signs, a periosteal reaction, a positive culture of aspirated joint fluid, and acute inflammation identified in tissue around the implant. There are several different mechanisms and modes of implant wear, and perhaps the most important cause of aseptic loosening is an inflammatory reaction to particles of wear debris. Abrasive, adhesive, and fatigue wear of polyethylene, metal and bone cement produces debris particles that induce bone resorption and implant loosening. Particles can cause linear, geographic, or erosive patterns of bone resorption (osteolysis), the distributions of which are influenced by the implant design. Micromotion of implants that did not achieve adequate initial fixation is another important mechanism of loosening. Fatigue failure at the bone/cement and bone/implant interface may cause aseptic loosening, and may be especially important for implants with relatively smooth surfaces. Stress shielding can influence local bone density, but is rarely an isolated cause of implant loosening. Elevated hydrodynamic pressure has been associated with bone resorption in the absence of implants, and may also play a role in implant loosening. Received: 29 March 1999 Revision requested: 5 May 1999 Revision received: 7 June 1999 Accepted: 9 June 1999     

神经性关节病：附115例临床X线分析

The clinical and radiological observations of 115 patients (163 joints) with neuroarthropathy (Charcot joint) were presented. The main clinical and typical X-ray findings as well as the radiologic features of different joints were described: (1) In Charcot joint of the shoulder, the entire scapula bone may be disintegrated; (2) After cleaning and arthrodesis, fragmentation of bone may reappear at both ends of the affected long bone and even the lateral surface of diaphysis; (3) Fragmentation of articular surface and subchondral bone may be seen in non-weight bearing surface; (4) 32 cases in our series had spontaneous fractures without history of trauma or undue strain; (5) Follow-up observation in short period (two to six weeks) showed rapid progressive destruction. The authors were of the opinion that neurotrophic theory seems to be the important pathogenesis of Charcot joint. While bone resorption should be the primary change. Bone hypertrophy and proliferation are secondary changes.     

Permanent Proplast temporomandibular joint implants: MR imaging of destructive complications

We studied the radiologic and pathologic changes in 30 patients (34 joints) in which there were locally destructive bone and soft-tissue complications associated with previously inserted permanent temporomandibular joint (TMJ) Proplast-Teflon implants. The cases were selected as representative examples of patients with failed Proplast interpositional arthroplasty, in whom images of the TMJ were obtained with conventional radiography, tomography, and MR, and in whom both surgical and histologic findings were available. Clinical indications for imaging included joint pain, restricted joint motion, crepitus, preauricular swelling, regional lymphadenopathy, malocclusion either acquired or changed since implant surgery, and facial deformity. Surgery was then performed for the purposes of implant retrieval and joint debridement because of destructive soft-tissue and osseous changes observed from the imaging analysis in conjunction with significant clinical signs and symptoms. The pathologic changes, observed 4-54 months after implant surgery, included a destructive foreign-body-type granuloma and avascular necrosis of the mandibular condyle and condylar neck. Our findings suggest that MR is useful in the detection and evaluation of destructive complications that may accompany failed Proplast-Teflon implants in the TMJ. MR is superior to conventional radiography and tomography in detecting soft-tissue lesions and avascular necrosis of bone. Tomography more accurately delineates soft-tissue calcifications and cortical margins of osseous structures.     

Functional adaptation of bone to exercise and injury

Bone adapts to altered physical stimuli, dietary changes, or injury. Dietary calcium and vitamins play important roles in maintaining skeletal health, but high-fat diets are pervasive in western cultures and may contribute to the increasing prevalence of osteoporosis and incidence of related hip fractures. Exercise helps maintain bone mass and counter osteoporosis, but exercise can also have detrimental effects-particularly for immature bone. Some negative exercise effects may also be linked to diet. For example, insufficient dietary protein during exercise can impair bone development and remodeling. Bone remodeling is a potent example of tissue repair. Chronically altered loading after a joint injury, however, can result in remodeling processes that can be detrimental to the joint. Anterior cruciate ligament injury, for example, commonly leads to osteoarthritis. Early changes in the periarticular cancellous bone may play a role in the development of knee osteoarthritis. Although these factors influence skeletal health, the mechanisms remain unclear by which bone interprets its environment and responds to mechanical stimuli or injury. To understand why different levels of exercise are beneficial or detrimental or why altered joint loading leads to changes in periarticular bone structure, underlying mechanisms must be understood by which bone interprets its mechanical environment.     

The "warm" sacroiliac joint. A finding in pelvic abscess

Two patients with pain referable to the low back and sacroiliac regions had bone scans with similar findings. In each, one sacroiliac joint was "warm" (uptake on that side was slightly greater than that in the contralateral area). Ga-67 imaging also demonstrated increased uptake in the same locale. Subsequent CT scanning revealed pelvic abscesses adjacent to the affected joints. Asymmetric uptake of bone imaging agent may have been related to hyperemia and "heating" of the sacroiliac joint. Rapid defervescence with antibiotics and drainage (and no CT evidence of bone involvement) suggested that osteomyelitis was not involved in these cases.     

SPECT in the study of pathology of the temporomandibular joint. The authors' personal experience]

Symptomatic temporomandibular joint dysfunctions may affect about 25% of the adult population, with a smaller though significant percentage of patients experiencing severe impairment. From 1986 through 1991, 107 patients with severe temporomandibular joint symptoms and with various temporomandibular joint disorders were evaluated with conventional radiology and with closed/open-mouth temporomandibular joint tomograms. Single-photon emission-computed tomography (SPECT) and planar imaging were performed on 32 patients using a rotating gamma camera equipped with a general purpose collimator. Transaxial, coronal and sagittal tomoscintigrams were reconstructed. Increased radiotracer uptake in the temporomandibular joint was regarded as a positive finding, and the intensity of temporomandibular joint activity was compared with that of adjacent calvarium using regions of interest. In the 32 patients submitted to scintigraphy, conventional radiology showed no pathologic patterns, while SPECT showed pathologic findings in 31 patients (97% of cases). The patient with normal temporomandibular joint findings on SPECT exhibited abnormal maxillary isotope uptake, ipsilateral to the symptoms. Our results indicate that SPECT is a simple, noninvasive, inexpensive and very sensitive screening test relative to the internal derangement of the temporomandibular joint. Moreover, it provides information which is not available by means of routine bone scans or X-ray studies. Thus, SPECT appears to be the modality of choice for patients whose clinical findings are equivocal or whose symptoms are unclear, and it can guide treatment strategies and be useful in the follow-up.     

The osteoclast—what’s new?

Bone resorption is required for skeletal modelling during bone growth and for mineral homeostasis and bone remodelling throughout life. Osteoclasts are multinucleated cells that are uniquely specialised to carry out this physiological bone resorption. As osteolysis is a feature of most diseases of bone and joint, osteoclasts also play a role in pathological bone resorption, the extent of which is a function of the cellular and molecular mechanisms that govern their formation and function.     

Radiographic evaluation of arthritis: degenerative joint disease and variations

In the presence of joint space narrowing, it is important to differentiate inflammatory from degenerative conditions. The presence of osteophytes, bone sclerosis, and subchondral cysts and the absence of inflammatory features such as erosions suggest osteoarthritis. Typical osteoarthritis involves specific joints at a particular patient age. When osteoarthritis involves an atypical joint, occurs at an early age, or has an unusual radiographic appearance, then other causes for cartilage destruction should be considered, such as trauma, crystal deposition, neuropathic joint, and hemophilia. There are several types of arthritis, such as juvenile chronic arthritis and gouty arthritis, that may have a variable appearance compared with that of other common inflammatory arthritides.     

Clinical application of SPHARM-PDM to quantify temporomandibular joint osteoarthritis

The severe bone destruction and resorption that can occur in osteoarthritis of the temporomandibular joint (TMJ) is associated with significant pain and limited joint mobility. However, there is no validated method for the quantification of discrete changes in joint morphology in early diagnosis or assessment of disease progression or treatment effects. To achieve this, the objective of this cross-sectional study was to use simulated bone resorption on cone-beam CT (CBCT) to study condylar morphological variation in subjects with temporomandibular joint (TMJ) osteoarthritis (OA). The first part of this study assessed the hypothesis that the agreement between the simulated defects and the shape analysis measurements made of these defects would be within 0.5 mm (the image's spatial resolution). One hundred seventy-nine discrete bony defects measuring 3 mm and 6 mm were simulated on the surfaces of 3D models derived from CBCT images of asymptomatic patients using ITK-Snap software. SPHARM shape correspondence was used to localize and quantify morphological differences of each resorption model with the original asymptomatic control. The size of each simulated defect was analyzed and the values obtained compared to the true defect size. The statistical analysis revealed very high probabilities that mean shape correspondence measured defects within 0.5 mm of the true defect size. 95% confidence intervals (CI) were (2.67, 2.92) and (5.99, 6.36) and 95% prediction intervals (PI) were (2.22, 3.37) and (5.54, 6.82), respectively for 3 mm and 6 mm simulated defects. The second part of this study applied shape correspondence methods to a longitudinal sample of TMJ OA patients. The mapped longitudinal stages of TMJ OA progression identified morphological variants or subtypes, which may explain the heterogeneity of the clinical presentation. This study validated shape correspondence as a method to precisely and predictably quantify 3D condylar resorption.     

Sclerosing bone dysplasias: review and differentiation from other causes of osteosclerosis

Sclerosing bone dysplasias are skeletal abnormalities of varying severity with a wide range of radiologic, clinical, and genetic features. Hereditary sclerosing bone dysplasias result from some disturbance in the pathways involved in osteoblast or osteoclast regulation, leading to abnormal accumulation of bone. Several genes have been discovered that, when disrupted, result in specific types of hereditary sclerosing bone dysplasia (osteopetrosis, pyknodysostosis, osteopoikilosis, osteopathia striata, progressive diaphyseal dysplasia, hereditary multiple diaphyseal sclerosis, hyperostosis corticalis generalisata), many of which exhibit similar pathologic mechanisms involving endochondral or intramembranous ossification and some of which share similar underlying genetic defects. Nonhereditary dysplasias include intramedullary osteosclerosis, melorheostosis, and overlap syndromes, whereas acquired syndromes with increased bone density, which may simulate sclerosing bone dysplasias, include osteoblastic metastases, Paget disease of bone, Erdheim-Chester disease, myelofibrosis, and sickle cell disease. Knowledge of the radiologic appearances, distribution, and associated clinical findings of hereditary and nonhereditary sclerosing bone dysplasias and acquired syndromes with increased bone density is crucial for accurate diagnosis.