The utility of MRI in predicting radiographic erosions in the metatarsophalangeal joints of the rheumatoid foot: a prospective longitudinal cohort study

INTRODUCTION: Magnetic resonance imaging (MRI) may reveal rheumatoid arthritis (RA) changes in the feet when hands are normal. The purpose of this study was to determine the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of a metatarsophalangeal (MTP) erosion on MRI to predict a subsequent radiographic erosion in the same joint. Similar analyses were performed for bone marrow edema, predicting a subsequent MRI erosion. Descriptive results of other lesions are reported. METHODS: Fifty patients with RA of less than 5 years' duration who were rheumatoid factor-positive and/or anti-cyclic citrullinated peptide-positive were recruited. Patients on anti-tumor necrosis factor (TNF) therapy were excluded. Anti-TNF therapy could begin after enrollment. MRI and radiographs of the 3rd, 4th, and 5th MTP joints bilaterally were taken at baseline and at 6, 12, and 24 months. Clinical data were collected. RESULTS: Fifty patients were recruited; 46 patients had suitable data. Results for MRI erosions predicting subsequent radiographic erosions for 6, 12, and 24 months, respectively, were as follows: sensitivity 0.75, 0.60, 0.75; specificity 0.93, 0.94, 0.94; PPV 0.086, 0.10, 0.17; NPV 0.998, 0.995, 0.995. Results for MRI bone marrow edema predicting MRI erosions at 6 and 12 months, respectively, revealed sensitivity 0.50, 0.67; specificity 0.97, 0.97; PPV 0.25, 0.50; NPV 0.99, 0.99. Synovitis was the most common finding and, when present in isolation, resolved on 67.3% of subsequent studies. MRI erosions persisted on subsequent studies with one exception. Forty-six percent of the cohort was on anti-TNF therapy after study inception. CONCLUSIONS: The PPV of MRI erosions to predict subsequent radiographic erosions was low. Similarly, the PPV of bone marrow edema to predict a later MRI erosion was low. Alternatively, the NPV of the absence of an MRI erosion or bone marrow edema predicts that a later radiographic erosion or MRI erosion will likely not develop. Anti-TNF therapies may have resulted in the lower-than-anticipated PPVs. MRI descriptions of bone edema may represent a more critical time to treat in order to avoid damage, whereas an MRI erosion represents more permanent damage. This study suggests that imaging modalities more sensitive than radiographs are necessary to monitor disease in the biologic era

Complications of the spine in ankylosing spondylitis with a focus on deformity correction

NKYLOSING spondylitis is a systemic inflammatory disease of unknown origin. Affected patients are predominantly but not exclusively male. Chronic inflammatory back pain is the most common presenting symptom and typically develops between the ages of 20 and 40 years. 65 Patients with AS can also have extra-articular manifestations such as ocular, cardiac, pulmonary, gastrointestinal, and renal involvement. A patient's susceptibility to the disease is largely genetically determined. 60 Because there is no single suitable laboratory test, clinicians must know as many of the characteristic signs and symptoms as possible to make a diagnosis. Even though AS is a systemic disease, the presenting symptoms, treatment, and morbidity are largely dependent on how the disease affects the spine. Thus, we believe that a review on spinal disease in AS will be of great value. In this review, we first describe the latest published algorithm to diagnose early disease and the classic inflammatory lesions. We then explore the diseased spine's susceptibility to noninflammatory lesions such as microfractures and deformity. We also describe other sequelae of AS, such as early osteoporosis and CES. Both the medical and surgical approaches to treatment are summarized. There is a special focus on osteotomy techniques. By the conclusion of the article, the clinician should have a better understanding of the diagnostic and treatment possibilities in AS spinal disease. Diagnosis of Inflammatory Back Pain and AS Because AS can markedly respond to the newer biological agents (discussed later), effective treatment of the disease requires early diagnosis. However, the high prevalence of back pain in the general population and the lack of radiographically demonstrated characteristic lesions in early AS often delay recognition of the disease. To make an early diagnosis, it is important to distinguish inflammatory from mechanical back pain on presentation. Factors consistent with inflammatory back pain include morning stiffness lasting longer than 30 minutes, onset of chronic back pain at an early age (before 35 years of age), improvement in pain with physical activity rather than with rest, awakening with back pain during the 2nd half of the night, alternating buttock pain, and a prolonged period of back pain. 48 One factor by itself does not have sufficient sensitivity or specificity to determine if the back pain is inflammatory. Note, however, that in a study of European patients with AS in which only 4 factors were considered, if 2 symptoms Abbreviations used in this paper: AS = ankylosing spondylitis; CES = cauda equina syndrome; DEXA = dual energy x-ray absorptiometry; HLA = human leukocyte antigen; MR = magnetic resonance; NSAID = nonsteroidal antiinflammatory drug; PSO = pedicle subtraction osteotomy; SPO = Smith-Peterson osteotomy; TNF = tumor necrosis factor