Gout: radiographic findings mimicking infection.

OBJECTIVE: To describe radiographic features of gout that may mimic infection. DESIGN AND PATIENTS: We report five patients with acute bacterial gout who presented with clinical as well as radiological findings mimicking acute bacterial septic arthritis or osteomyelitis. Three patients had delay in the appropriate treatment with the final diagnosis being established after needle aspiration and identification of urate crystals under polarized light microscopy. Two patients underwent digit amputation for not responding to antibiotic treatment and had histological findings confirming the diagnosis of gout. CONCLUSION: It is important for the radiologist to be aware of the radiological manifestations of acute gout that can resemble infection in order to avoid inappropriate diagnosis and delay in adequate treatment. The definitive diagnosis should rely on needle aspiration and a specific search for urate crystals.

A comparison of lower extremity muscle strength, obesity, and depression scores in elderly subjects with knee pain with and without radiographic evidence of knee osteoarthritis.

OBJECTIVE: To determine, in subjects with knee pain but no radiographic changes of tibiofemoral or patellofemoral compartment osteoarthritis (OA), whether mean body weight, quadriceps and hamstring strength, lower extremity muscle mass, depression scores, and perceptions of their general health status differed from those of subjects with symptomatic knee OA. METHODS: Subjects were 25 women and 10 men with knee pain and radiographic evidence of OA at the baseline examination, and 21 women and 16 men who had knee pain at the baseline examination but no radiographic evidence of knee OA at either baseline examination or followup evaluation performed, on average, 31 months later. These individuals were a subset of a cohort of 462 independently living elderly individuals recruited by telephone interview after random selection through random digit dialing of households in central Indiana. Data from an additional 134 subjects who had neither knee pain nor radiographic changes of OA at either the baseline or followup examination were analyzed for comparison. Lower extremity muscle strength was measured by isokinetic dynamometry, lean tissue (i.e., muscle) mass in the lower extremities by dual x-ray absorptiometry, depression by Center for Epidemiology Depression (CES-D) scale. knee pain by Western Ontario McMaster University OA instrument, and perceived general health status by the Medical Outcome Survey Short Form-36. RESULTS: In contrast to those with symptomatic knee OA, those who had knee pain but no radiographic evidence of OA were less obese, had hamstring as well as quadriceps weakness, and had CES-D scores high enough to qualify for a diagnosis of clinical depression. CONCLUSION: Among subjects with knee pain but no OA--and among women in this subset, in particular--knee pain may be a manifestation of depression. rather than of joint disease.

Quadriceps strength in women with radiographically progressive osteoarthritis of the knee and those with stable radiographic changes.

OBJECTIVE: To explore the relationship between lower extremity weakness and the progression of established radiographic changes of knee osteoarthritis (OA). METHODS: The study cohort of 342 elderly subjects was recruited from central Indiana by random digit dialing. We analyzed 79 subjects who had definite radiographic changes of unilateral or bilateral knee OA at baseline and for whom baseline data for lower extremity muscle strength and lean tissue mass and baseline and followup assessments of knee pain were available. Radiographs were graded for severity of OA at baseline and again about 2.5 years later (mean 31.5 months). Knee pain was evaluated at the same examination. Strength of the knee flexors and extensors was assessed bilaterally at baseline by isokinetic dynamometry and lower extremity muscle mass by dual energy x-ray absorptiometry. RESULTS: Mean peak knee extensor strength of women with progressive OA, before and after adjustment for lower extremity muscle mass, was about 9% lower than that in those with stable radiographic changes, but this difference was not statistically significant. No difference was apparent between the 2 groups with respect to knee flexor (hamstring) strength. The decrease in quadriceps strength among women with progressive OA, relative to those with stable OA, did not appear to be attributable to knee pain, and knee extensor strength at baseline bore no apparent relationship to the development or progression of knee pain among those with OA. CONCLUSION: We have shown previously that quadriceps weakness may be of etiologic importance in development of knee OA. The absence of a significant difference in quadriceps strength between subjects with radiographically stable OA and those whose joint damage progressed suggests that factors other than quadriceps weakness are more important determinants of OA progression.

Magnetic resonance imaging of osteoarthritis.

Considering the plethora of imaging protocols, joint-specific orientations, and potential artifacts, the design and interpretation of MR imaging examination is difficult. Like a physical examination, these considerations must be tailored to the specific tissue, joint, and clinical question under consideration. Shortcomings of MR imaging include the lack of consensus among radiologists with respect to which protocols best image articular joints. To date, few prospective studies have been undertaken to assess osteoarthritis by MR imaging. Diagnostic imaging is central to staging the severity of osteoarthritis and assessing the efficacy of therapeutic osteoarthritis. Plain film radiography is insensitive for identifying early changes of osteoarthritis. Tailored MR imaging, producing high spatial and or contrast resolution images, is proving to be an important tool in the early detection and surveillance of osteoarthritis progression. Future therapeutic techniques, such as chondrocyte transplantation, use of growth factors, or cartilage protease inhibitors requires high resolution and volumetric MR imaging studies for accurate identification of focal articular cartilage defects and generalized cartilage loss. Creation of cartilage models by three-dimensional MR image rendering may be helpful for preoperative planning of orthopedic surgical procedures in advanced cases of osteoarthritis. More work needs to be done in high resolution and volumetric MR imaging of articular cartilage. Given the availability of new disease-modifying treatments designed to prevent, delay the progression of, or reverse osteoarthritis, additional prospective MR imaging studies need to be undertaken to improve the reproducibility of MR imaging as a primary outcome measure in the evaluation of osteoarthritis. Interinstitutional standardization of specific MR imaging magnet strengths, surface coils, joint orientations, sequences used, scoring systems and quality assurance methodologies are needed to establish the reproducibility of MR imaging and interpretation for assessment of patients with osteoarthritis.

Reduced quadriceps strength relative to body weight: a risk factor for knee osteoarthritis in women?

OBJECTIVE: To determine whether baseline lower extremity muscle weakness is a risk factor for incident radiographic osteoarthritis (OA) of the knee. METHODS: This prospective study involved 342 elderly community-dwelling subjects (178 women, 164 men) from central Indiana, for whom baseline and followup (mean interval 31.3 months) knee radiographs were available. Lower extremity muscle strength was measured by isokinetic dynamometry and lean tissue (i.e., muscle) mass in the lower extremities by dual x-ray absorptiometry. RESULTS: Knee OA was associated with an increase in body weight in women (P = 0.0014), but not in men. In both sexes, lower extremity muscle mass exhibited a strong positive correlation with body weight. In women, after adjustment for body weight, knee extensor strength was 18% lower at baseline among subjects who developed incident knee OA than among the controls (P = 0.053), whereas after adjustment for lower extremity muscle mass, knee extensor strength was 15% lower than in the controls (P not significant). In men, in contrast, adjusted knee extensor strength at baseline was comparable to that in the controls. Among the 13 women who developed incident OA, there was a strong, highly significant negative correlation between body weight and extensor strength (r = -0.740, P = 0.003), that is, the more obese the subject, the greater the reduction of quadriceps strength. In contrast, among the 14 men who developed incident OA, a modest positive correlation existed between weight and quadriceps strength (r = 0.455, P = 0.058). No correlation between knee flexor (hamstring) strength and knee OA was seen in either sex. CONCLUSION: Reduced quadriceps strength relative to body weight may be a risk factor for knee OA in women.

Quadriceps weakness and osteoarthritis of the knee.

BACKGROUND: The quadriceps weakness commonly associated with osteoarthritis of the knee is widely believed to result from disuse atrophy secondary to pain in the involved joint. However, quadriceps weakness may be an etiologic factor in the development of osteoarthritis. OBJECTIVE: To explore the relation between lower-extremity weakness and osteoarthritis of the knee. DESIGN: Cross-sectional prevalence study. SETTING: Population-based, with recruitment by random-digit dialing. PARTICIPANTS: 462 volunteers 65 years of age or older. MEASUREMENTS: Radiographs of the knee were graded for the presence of osteoarthritis. Knee pain and function were assessed with the Western Ontario and McMaster Universities Arthritis Index, the strength of leg flexors and extensors was assessed with isokinetic dynamometry, and lower-extremity lean tissue mass was assessed with dual-energy x-ray absorptiometry. RESULTS: Among participants with osteoarthritis, quadriceps weakness, but not hamstring weakness, was common. The ratio of extensor strength to body weight was approximately 20% lower in those with than in those without radiographic osteoarthritis. Notably, among women with tibiofemoral osteoarthritis, extensor weakness was present in the absence of knee pain and was seen in participants with normal lower-extremity lean mass (extensor strength, 30.1 lb-ft for those with osteoarthritis and 34.8 lb-ft for those without osteoarthritis; P < 0.001). After adjustment for body weight, age, and sex, lesser quadriceps strength remained predictive of both radiographic and symptomatic osteoarthritis of the knee (odds ratio for prevalence of osteoarthritis per 10 lb-ft loss of strength, 0.8 [95% CI, 0.71 to 0.90] for radiographic osteoarthritis and 0.71 [CI, 0.51 to 0.87] for symptomatic osteoarthritis). CONCLUSION: Quadriceps weakness may be present in patients who have osteoarthritis but do not have knee pain or muscle atrophy; this suggests that the weakness may be due to muscle dysfunction. The data are consistent with the possibility that quadriceps weakness is a primary risk factor for knee pain, disability, and progression of joint damage in persons with osteoarthritis of the knee.

Osteonecrosis, transient osteoporosis, and transient bone marrow edema: current concepts.

Osteonecrosis, transient osteoporosis, and transient bone marrow edema are closely related diseases that may have an overlapping clinical and radiographic presentation, thus creating difficulty in establishing a diagnosis. Close scrutiny of MR images may aid in distinguishing the pattern of osteonecrosis from other conditions, but in other cases careful clinical and radiologic follow up may be required. The pathogenesis, radiologic diagnosis, and clinical relevance of these conditions are described and reviewed in this article.

Kinematic magnetic resonance imaging of the normal shoulder: assessment of the labrum and capsule.

OBJECTIVE: To examine the normal shoulder, specifically the labrum and the capsule, with kinematic magnetic resonance imaging (MRI) in asymptomatic volunteers. SUBJECTS AND METHODS: Fourteen asymptomatic volunteers 22 to 53 years of age were studied with a 1.5-T Signa Advantage imager (GE Medical Systems, Milwaukee). Successive static gradient-echo images were obtained in the transverse plane at the mid-glenoid level as the shoulder was successively positioned from full internal to full external rotation. These images were correlated with standard transverse T1-weighted spin-echo images and gradient-echo volume images obtained in the neutral position. RESULTS: The anterior labrum was slightly mobile during rotation in 11 subjects and changed shape from blunted or round to triangular in 8 subjects. A wide variation in morphologic features of the anterior labrum was observed. During rotation, a slight increase in signal intensity was noted in the anterior labrum of five of the subjects. The posterior labrum maintained a relatively stable triangular shape in most cases. Dynamic study allowed assessment of the anterior capsule insertion in all cases. Three subjects had type 1 and 11 had type 2 capsular insertion. No cases of type 3 insertion were identified. CONCLUSIONS: Variation in the shape and signal intensity of the anterior labrum observed in normal asymptomatic volunteers during transverse kinematic examination of the shoulder should be taken into account during evaluation of shoulder instability, since this variation may be clinically insignificant. Kinematic MRI allows easy evaluation of the anterior capsule.

Amyloidosis of the shoulder in patients on chronic hemodialysis: sonographic findings.

OBJECTIVE: The purpose of this study was to determine the sonographic findings of amyloidosis in shoulders of patients on chronic hemodialysis. SUBJECTS AND METHODS: Sonograms were obtained for 19 shoulders of 11 patients on chronic hemodialysis with clinical findings suggestive of amyloidosis. Five patients had biopsy-proven amyloidosis, and one patient had positive shoulder joint fluid aspirate. The thicknesses of the following structures were measured: the rotator cuff, the subacromial-subdeltoid bursa, and the long head of the biceps tendon and its synovial sheath. The presence of intra- or periarticular masses or nodules, hyperechoic areas, bony erosions, and calcifications was specifically assessed. Shoulder sonograms from dialysis patients were compared with normal sonograms obtained for 20 asymptomatic shoulders of patients without renal disease. RESULTS: The mean rotator cuff thickness in the patients with amyloidosis was significantly greater than that in the normal group (p < .0001). Ten shoulders of six patients with amyloidosis but none of the control subjects had a rotator cuff thickness greater than 7 mm. The synovial sheath of the long head of the biceps tendon was thickened in 10 shoulders of patients with amyloidosis and in one normal shoulder. The subacromial-subdeltoid bursa was thickened in seven shoulders of patients with amyloidosis but not in any shoulders in the control group. Eight shoulder sonograms from dialysis patients showed intra- or periarticular nodules. CONCLUSION: Sonographic findings associated with amyloidosis of the shoulder include thickening of the rotator cuff, the synovial sheath of the long head of the biceps tendon, and the subacromial-subdeltoid bursa and the presence of nodules within or around the joint. Shoulder sonography may be useful as a noninvasive technique for the diagnosis of dialysis-related amyloidosis in the proper clinical setting.

Bupivicaine arthrography of the post-arthroplasty hip.

Addition of bupivicaine, a medium-length-acting local anesthetic, to the contrast material in arthrography of total hip prostheses provides reliable information as to whether the source of pain is intracapsular or extracapsular. In 12 surgically proven cases, complete relief of pain after bupivicaine injection correctly identified an intracapsular source of pain in 10, with only 1 false-positive and 1 false-negative. These results compare favorably with the results of the contrast arthrograms in these patients in localizing the pain even if a specific diagnosis could not be reached. Bupivicaine as an adjunct to contrast material during arthrography provides additional information useful in management decisions regarding the necessity of revision arthroplasty.

Occult dorsal carpal ganglion: comparison of US and MR imaging.

PURPOSE: To evaluate the usefulness of ultrasound (US) and magnetic resonance (MR) imaging in patients suspected of having an occult dorsal carpal ganglion. MATERIALS AND METHODS: The authors prospectively studied US and MR images of 14 wrists in 13 consecutive patients suspected of having an occult dorsal carpal ganglion. RESULTS: Eleven dorsal carpal ganglia were identified with US and nine with MR imaging. One patient refused the MR imaging study. Of two equivocal cases at MR imaging, one was a ganglion and another was a compressible capsular recess, as determined at US. One ganglion was missed with both techniques. The average diameter of the ganglion cysts was 4.9 mm. CONCLUSION: MR imaging and US are equally effective in the detection of occult dorsal carpal ganglia. Because of its dynamic capabilities and lower cost, US should be the initial imaging procedure for suspected occult dorsal carpal ganglia.

Case report 824: Tuberculosis presenting as a soft tissue forearm mass in a patient with a negative tuberculin skin test.

Tuberculosis presenting as a soft tissue mass is rare. The diagnosis should be considered in patients with radiographic findings of massive soft tissue swelling and cortical bone destruction. Such patients may present with few clinical findings and have no evidence of prior exposure to tuberculosis or history of immunosuppression. Computed tomography may be of use in distinguishing infection from malignancy.

Carpal instability in rheumatoid arthritis.

The authors examined prospectively the prevalence of and relations among patterns of carpal instability in 52 patients with proven rheumatoid arthritis. Posteroanterior, lateral and oblique radiographs of both wrists were obtained. Nineteen patients exhibited one or more patterns of instability. The most common isolated pattern was volar intercalated segmental instability, apparent in six patients. Five patients showed more than one pattern, most commonly a combination of ulnar translocation and volar carpal subluxation. Patients with active erosions or changes in the distal radioulnar joint were more likely to exhibit instability than those without such findings. Carpal instability is a frequent mechanical complication of rheumatoid arthritis. The radiologist should be aware of this possibility, so that a diagnosis can be made promptly and appropriate clinical management begun.

MR imaging of meniscal tears: narrow versus conventional window width photography.

Narrow window width photography of magnetic resonance (MR) images of knee menisci is promoted as a useful tool in the detection of meniscal tears. To assess the diagnostic efficacy of this method, conventional and narrow window width MR images of 48 patients (96 menisci, 37 tears) were interpreted by two experienced observers. Images were graded on a five-point scale to enable receiver operating characteristic (ROC) curve analysis. The ROC curves constructed from the conventional window width interpretations were similar to those of the narrow window width interpretations for both observers. It was not possible to prove that the areas under the two curves were significantly different. This suggests that there is no globally significant improvement in the detection of meniscal tears when narrow window width images are used for interpretation.

Prospective study of magnetic resonance imaging and SPECT bone scans in renal allograft recipients: evidence for a self-limited subclinical abnormality of the hip.

We recently reported that typical abnormalities of avascular necrosis (AVN) in magnetic resonance images (MRI) of the hips of asymptomatic renal transplant recipients whose plain radiographs are normal may improve spontaneously and even disappear completely. We present the results of serial bone scans, most of which were performed with single-photon emission computed tomography obtained over periods as long as 24 mo after transplantation in 72 of these patients. Three paired imaging studies (i.e., MR and bone scan performed within 30 days of each other) were available for each of these patients. In three patients, both the MR images and the bone scans showed changes consistent with bilateral AVN within 4 mo after transplantation. All three patients developed hip pain which was bilateral in two and unilateral in one. Two patients (three hips) required surgical intervention at which time AVN was found on pathologic examination of all three hips. None of the remaining 69 patients developed hip pain during the study. However, in nine patients whose MR studies were consistently normal, at least one bone scan was abnormal (13 hips). The presence of AVN was pathologically confirmed in each of the hips subjected to surgery. Where the imaging findings were identical to those in the asymptomatic patients as well as those in whom the imaging abnormality regressed, we suggest that the subclinical imaging abnormalities represent mild AVN, which is reversible in some cases. Since the process was identified in 10 hips by MRI and in 13 hips by bone scan, both studies are needed to detect subclinical AVN. This may be important if treatment of subclinical disease is clearly shown to prevent progression to symptomatic AVN.