Familial resemblance of bone mineral density (BMD) and calcaneal ultrasound attenuation: the BMD in mothers and daughters study.

The familial resemblance in bone mineral density (BMD) and calcaneal broadband ultrasound attenuation (BUA) was examined in 207 mother-daughter pairs. Mothers were participants in the Study of Osteoporotic Fractures. Three groups of daughters were recruited based on their maternal history of "fracture," "low BMD" without fracture (< 0.58 g/cm2, t-score < -2.5), and "normal BMD" without fracture (> 0.67 g/cm2, t-score > -1.6). Data on other potentially heritable factors known to influence BMD and BUA were also collected. BMD was measured at the hip, spine, whole body, and calcaneus. Calcaneal BUA was assessed using the Walker-Sonix UBA 575. Total hip and femoral neck BMD were significantly lower (5.0-8.0%, p < 0.017) among daughters, in particular premenopausal daughters, of mothers with established osteoporosis ("fracture" or "low BMD") compared with daughters of mothers at lower risk of osteoporosis ("normal BMD"). BUA did not differ across daughter groups. Lifestyle characteristics (dietary calcium, smoking, physical activity) were not highly correlated in mothers and daughters. Height, weight, and body composition were significantly correlated within mother-daughter pairs and could be a potential mechanism by which BMD is inherited. Among pre- and postmenopausal daughters, heritability estimates ranged from 50-63% and 34-48%, respectively. Heritability for calcaneal BUA (53%) was evident among postmenopausal daughters only. In conclusion, familial association in BMD was strongest among premenopausal daughters. Estimates of heritability suggest that maternal BMD and BUA are important independent predictors of BMD and BUA among daughters, reinforcing the importance of prevention and early intervention among women with a positive family history of osteoporosis.

Fractal analysis of trabecular patterns in projection radiographs. An assessment.

RATIONALE AND OBJECTIVES: Fractal analysis of digitized images has been investigated in recent years as a potential measure of structural bone strength. Several technical issues associated with such measurements are assessed. METHODS: In a series of experiments using a hand phantom, the effects of system noise and modulation transfer function on fractal dimension were explored. The authors evaluated a method for correcting the estimated power spectrum using a step-wedge image exposed and digitized under identical conditions as a reference. RESULTS: System noise and modulation transfer function significantly affect estimated fractal dimension in bony regions computed from conventional radiographs. CONCLUSIONS: Before conventional radiographs are used for fractal analysis in the clinical environment, many of the technical problems associated with this methodology must be addressed.

Multipoint rank-order study methodology: observer issues.

RATIONALE AND OBJECTIVES: We performed a multipoint rank-order experiment to evaluate variability in observers' sensitivity to small differences in image presentation and to assess observers' performance as a function of the type and number of tasks included. METHODS: Five experienced observers were presented with four sets of chest images that had been compressed at five different levels. Each set contained six images ranging from noncompressed to approximately 60:1-compressed images. Observers were asked to review all images of each case side by side and rank-order the "quality" of each to enable determination of the presence or absence of interstitial disease and/or pneumothoraces. RESULTS: Observers varied significantly in their ability to detect very small differences among the images (P < 0.001). Those who performed well did so regardless of whether they ranked a specific abnormality in a multidisease or a single-disease setting. CONCLUSIONS: Selected observers can reliably detect very small differences among similar images. These readers could be used to confirm or rule out the need for objective observer-performance-type studies.

Effect of probenecid on the urinary excretion of TXB2 and PGE2 in the anaesthetised rat.

In the anaesthetised rat, probenecid (33 mg/kg) produced a 50% fall in urinary TXB2 excretion indicating that a component of the TXB2 excreted in the urine is secreted by the proximal tubule. At a higher dose of probenecid (100 mg/kg) this effect was overcome, a relative increase in urinary TXB2 excretion being produced. This may provide evidence for the proximal reabsorption or bi-directional transport of TXB2 in the rat. At 100 mg/kg probenecid also produced an 8-fold increase in urinary PGE2 excretion. Although the bi-directional transport of PGE2 is well known, this is the first time urinary PGE2 excretion rate has been shown to be modified by probenecid. The increase in PGE2 excretion could obscure the assessment of any inhibition by probenecid of proximal PGE2 secretion. It could also provide evidence for the proximal reabsorption of PGE2. However the interpretation of probenecid-induced changes in eicosanoid excretion in terms of modified tubular reabsorption must be treated with caution since urinary eicosanoid excretion could be increased by other properties of probenecid including inhibition of either protein binding or the uptake of eicosanoids into the lung.

Change in trabecular architecture as measured by fractal dimension.

The objective of this work was to expose dried trabecular bone material to a decalcifying environment and to quantify the change in the spatial distribution of the bone with a fractal measure. Digitized radiographic images were produced from four separate slices of human vertebral bone as they dissolved within a solution of nitric acid. Pixel data from a region of interest (ROI) within the trabecular bone were used to estimate the time-dependent change in fractal dimension of the ROI as the bone dissolved. Results demonstrated that a change in the spatial distribution of trabecular material may be expressed in terms of a concurrently changing estimate of the fractal dimension.

Selection of processing algorithms for digital image compression: a rank-order study.

RATIONALE AND OBJECTIVES: We investigated non-receiver operating characteristic (non-ROC) methods for the selection of processing algorithms for digital image compression. METHODS: We performed a multipoint, rank-order study with 20 posteroanterior chest images, each processed using four different algorithms. Seven radiologists reviewed these alongside the digitized noncompressed image. Observers were forced to rank order the similarity and/or difference of the processed images to the nonprocessed image in each case. RESULTS: A two-way analysis of variance of the rankings was statistically significant (p = .025), indicating that one processing scheme yielded images that were clearly perceived as the most similar to the nonprocessed images. The selected processing scheme was not the one that yielded the lowest quantitative difference from the nonprocessed images as measured by root mean square error. CONCLUSION: Non-ROC study designs that are highly sensitive to small differences among similar images can be used to select processing algorithms.

A methodology to evaluate motion of the unstable spine during intubation techniques.

Airway management in patients with an unstable cervical spine remains a challenge. A video fluoroscopic technique that transfers the image to a floppy disk for direct measurement is described. This technique enabled standardized, direct measurement of the cervical spine during airway maneuvers before and after a C5-6 posterior instability was surgically created in five cadaveric specimens. Unsupported direct oral techniques often can cause more motion than do indirect nasal techniques, and chin lift/jaw thrust and cricoid pressure can cause as much motion as do some of the intubation techniques.

The use of intravenous contrast in MRI of extremity infection.

Infection of the musculoskeletal system encompasses a variety of conditions, affecting skin, fascia, muscle, joints, tendon sheaths, and bone. In addition to features unique to each tissue site, these processes vary with respect to organism virulence, overall host condition, and the condition of the extremity itself, particularly its circulation. Treatment of musculoskeletal infection varies according to these features, and with respect to the presence of devitalized tissue. Unfortunately, while clinical examination is accurate for the presence of infection as a process in most circumstances, it lacks specificity for the variety of disorders within the spectrum of extremity infection. MRI examination using intravenous contrast is becoming the preferred modality to study complicated extremity infections, since it provides an accurate portrayal of the extent of osseous and non osseous involvement, and identifies areas of necrosis. This information provides a basis from which clinicians may more accurately choose from among treatment options.

Shoulder imaging abnormalities in individuals with paraplegia.

Shoulder pain and rotator cuff tears are highly prevalent in individuals with paraplegia (PP). The purpose of this study was to use magnetic resonance imaging (MRI), plain radiographs, questionnaires, and physical examination to gain insight into the prevalence of shoulder disorders in individuals with PP. A total of 28 individuals with PP was recruited (mean age=35; mean year from injury=11.5). Each subject completed a questionnaire designed to identify arm pain, had a standard physical examination focusing on the shoulder, and underwent imaging studies (radiographic and MRI). Nine of the thirty-two subjects (36 percent) experienced shoulder pain in the month prior to testing. The MRI studies documented only one rotator cuff tear. Five subjects showed osteolysis of the distal clavicle by plain radiographic study. In two subjects this was seen bilaterally. Although no relationship was seen between pain and imaging abnormalities, stepwise linear regressions found a statistically significant positive relationship between imaging abnormalities and body mass index (BMI) (radiographic: beta= 0.56, p<0.01; MRI: beta=0.52, p<0.01). This study found a low prevalence of rotator cuff tears and a high prevalence of distal clavicle osteolysis in a sample of relatively young individuals with PP. Although there was only one tear identified by MRI, a number of subclinical abnormalities were seen and found to correlate with BMI.

The seronegative spondyloarthropathies.

The four seronegative spondyloarthropathies can be divided into two main groups by their pattern of sacroiliitis and spondylitis (Table 1). The axial skeletal changes of ankylosing spondylitis and enteropathic arthropathy are often indistinguishable, as are those of psoriatic arthritis and Reiter's syndrome. Early proximal appendicular joint involvement in ankylosing spondylitis is a poor prognostic sign except in women where peripheral arthritis is more common, but has a more benign course. Peripheral joint destruction in enteropathic arthropathy is rare because treatment of the bowel disease also treats the arthritis. Distal appendicular involvement is characteristic of psoriatic arthritis and Reiter's syndrome. Proliferative erosions and enthesitis, periostitis, and normal mineralization aid in differentiating psoriatic arthritis and Reiter's syndrome from rheumatoid arthritis. The distribution of arthritis also differs from that seen in classic rheumatoid arthritis, with asymmetry and involvement of the distal interphalangeal joints more common in psoriatic disease and Reiter's syndrome.

Carpal impaction with the ulnar styloid process: treatment with partial styloid resection.

Carpal impaction with the ulnar styloid process (stylocarpal impaction) occurs less frequently than with the ulnar head (ulnocarpal impaction), and more commonly develops in wrists with negative ulnar variance. Physical examination, radiographic evaluation, and wrist arthroscopy are all helpful in excluding alternative causes of ulnar wrist pain. When an ulnocarpal stress test elicits pain, and radiographs suggest that this is due to carpal impaction with the ulnar styloid, partial resection of the styloid process provides successful treatment, so long as the insertion of the triangular fibrocartilage at the base of the styloid is not disrupted.

Retrograde drilling of osteochondral lesions of the medial talar dome.

Sixteen patients (16 ankles) with symptomatic osteochondral lesions of the medial talar dome were treated arthroscopically with percutaneous retrograde drilling through the sinus tarsi. The surgical technique allows preservation of intact articular cartilage, in contrast to traditional methods. All patients treated with this technique during a 24-month period were included in the study. Patient age ranged from 16 to 44 years (mean, 33 years). Follow-up ranged from 19 to 38 months (mean, 24 months). A staging system based on magnetic resonance imaging examination was used to grade the lesions preoperatively. Outcome was evaluated using the American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scale. Preoperative scores ranged from 35 to 75 points, with a mean of 53.9 points. Postoperative American Orthopaedic Foot and Ankle Society scores ranged from 48 to 100 points, with a mean of 82.6 points. Mean improvement was 25 points. There were no surgical complications. Short-term results were comparable to results reported with other available techniques.

Meniscal root injury and spontaneous osteonecrosis of the knee: an observation.

We describe injuries to the posterior root of the medial meniscus in patients with spontaneous osteonecrosis of the medial compartment of the knee. We identified 30 consecutive patients with spontaneous osteonecrosis of the medial femoral condyle. The radiographs and MR imaging were reviewed. We found tears of the posterior root of the medial meniscus in 24 patients (80%). Of these, 15 were complete and nine were partial. Complete tears were associated with > 3 mm of meniscal extrusion. Neither the presence of a root tear nor the volume of the osteonecrotic lesion were associated with age, body mass index (BMI), gender, side affected, or knee alignment. The grade of osteoarthritis was associated with BMI. Although tears of the posterior root of the medial meniscus were frequently present in patients with spontaneous osteonecrosis of the knee, this does not prove cause and effect. Further study is warranted.

Tubular mechanisms determining the urinary excretion of tritiated prostaglandin E2 in the anaesthetized rat.

1. The renal excretion of arterially injected tritiated prostaglandin E2 ([3H]PGE2) and its metabolites has been examined in the anaesthetized rat before and after the administration of probenecid (an inhibitor of proximal organic acid secretion). [14C]Inulin was employed as a freely filtered, non-reabsorbable marker, while [3H]p-aminohippurate was used to assess the inhibitory effect of probenecid. The experiments allowed us to quantify the tubular delivery, proximal secretion, intratubular metabolism, and tubular reabsorption of [3H]PGE2 by the whole kidney in vivo. 2. Following a single pass through the left kidney 25% of an injected dose of [3H]PGE2 was excreted, although only 1.7% of the injected 3H co-chromatogrammed with cold PGE2. The chemical content of PGE2 in the isotope employed, produced a slight but significant (P less than 0.05) fall (12%) in the single-pass excretion of [14C]inulin. 3. Intravenous probenecid (100 mg kg-1 + 100 mg kg-1 h-1) completely inhibited the proximal tubular secretion of [3H]p-aminohippurate, while the single-pass excretion of [14C]inulin remained unchanged. Probenecid also reduced the blood pressure and urine flow, and decreased the binding of [3H]PGE2 to plasma protein from 59 to 41%. 4. Probenecid administration reduced the single-pass excretion of 3H following an injection of [3H]PGE2 by 65% down to 8.5% of the injected dose. Due to the change in protein binding however, probenecid also increased the filtered load of [3H]PGE2 from 12 to 16% of the injected dose. 5. The following calculations were made concerning the tubular handling of [3H]PGE2 by the whole kidney in vivo. (i) Thirty-five per cent of the injected dose of [3H]PGE2 was secreted by the proximal tubules on a single pass through the kidney, in addition 12% was filtered while 59% was protein bound. (ii) The tubular reabsorption of [3H]PGE2 was 47% of the filtered load. (iii) [3H]PGE2 was subject to a high degree of intratubular metabolism which at a minimum value represented about 50% of the filtered load. The metabolism of [3H]PGE2 also occurred during proximal tubular secretion.

Anterior approach for knee arthrography.

OBJECTIVE: To develop a new method of magnetic resonance arthrography (MRA) of the knee using an anterior approach analogous to the portals used for knee arthroscopy. DESIGN: An anterior approach to the knee joint was devised mimicking anterior portals used for knee arthroscopy. Seven patients scheduled for routine knee MRA were placed in a decubitus position and under fluoroscopic guidance a needle was advanced from a position adjacent to the patellar tendon into the knee joint. After confirmation of the needle tip location, a dilute gadolinium solution was injected. RESULTS AND CONCLUSION: All the arthrograms were technically successful. The anterior approach to knee MRA has greater technical ease than the traditional approach with little patient discomfort.

MR imaging of the foot: utility of complex oblique imaging planes.

Successful MR imaging of the foot presents special challenges to the radiologist. Accurate and confident diagnosis presupposes the ability to produce high-resolution images of obliquely oriented, relatively small structures. Orienting the foot within an appropriate local coil to bring such structures into an orthogonal imaging plane, or even into a conventional oblique plane, may be impossible or intolerably uncomfortable for the patient. The frequent result is motion artifacts, which are accentuated when using a small field of view. However, when patients are comfortably positioned, the anatomy of interest often lies in a plane that is not orthogonal to any of the conventional imaging planes. Fortunately, commercially available MR imaging equipment can produce images in complex oblique planes with relative ease. In this pictorial essay, we discuss the technical considerations for expedient diagnostic MR imaging of the complex anatomy of the foot and illustrate our experiences with this technique.

Revision total hip arthroplasty with a retroperitoneal approach to the iliac vessels.

Although vascular complications during revision total hip arthroplasty are rare, the results can be devastating. Reports in the literature describe staged operations, with the first procedure being abdominal to remove cement and/or the acetabular component followed by a second joint reconstruction procedure. A protocol was developed that combines a retroperitoneal approach with revision total hip arthroplasty in one operative procedure in patients at risk for vascular injury. The patient first undergoes a retroperitoneal incision and the iliac artery and vein are dissected free of surrounding tissue. A silicone loop is placed around the iliac artery and vein and brought out through the wound. The wound is temporarily closed using staples. Revision total hip arthroplasty then proceeds in the usual fashion. If hemorrhage is encountered, bleeding can be rapidly controlled by tensioning the abdominal vessel loops and opening the incision for exposure to the vessels. No complications have been encountered in 23 patients when using this approach.

Are MR imaging signs of meniscocapsular separation valid?

PURPOSE: To define the positive predictive value (PPV) for the magnetic resonance (MR) imaging diagnosis of meniscocapsular separation in the knee. MATERIALS AND METHODS: The MR reports of 52 patients aged 16-75 years who had a prospective MR diagnosis of meniscocapsular injury were correlated with arthroscopic results. MR images obtained in 50 of these patients were retrospectively reviewed for specific signs of meniscocapsular separation, which included meniscal displacement, peripheral meniscal corner tears, increased perimeniscal signal intensity, fluid deep to the medial collateral ligament, and abnormal lateral fascicles. MR findings were correlated with arthroscopic findings. RESULTS: For the prospective MR interpretations, the PPV for meniscocapsular separation was 9% medially and 13% laterally. Meniscal displacement (measured from the meniscal edge to the tibia) was as great as 10 mm medially or 13 mm laterally without meniscocapsular tears at arthroscopy. Meniscal displacement did not correlate with effusion. Meniscal corner tears had a PPV of 0% medially and 50% laterally. Fluid at the meniscocapsular border and fluid deep to the medial collateral ligament were poor predictors of meniscocapsular abnormalities. Abnormal-appearing meniscal fascicles had a PPV of 8% for lateral meniscocapsular separation. CONCLUSION: The PPV for the MR diagnosis of meniscocapsular separation is low; the reported MR signs correlate poorly with arthroscopic findings.

MR imaging of knees having isolated and combined ligament injuries.

OBJECTIVE: Although clinical evaluation and MR imaging both accurately reveal injuries in knees with isolated ligament tears, physical examination becomes progressively less reliable when multiple lesions exist. We investigated the accuracy of MR imaging of knees having varying degrees and numbers of ligament injuries. SUBJECTS AND METHODS: We prospectively interpreted the MR images of 340 consecutive injured knees and compared these interpretations with the results of subsequent arthroscopy or open surgery, which served as the gold standard. Our interpretations of MR images focused on five soft-tissue supporting structures (the two cruciate ligaments, the two collateral ligaments, and the patellar tendon) and the two menisci. Patients were divided into three groups: no ligament injuries, single ligament injuries, and multiple ligament injuries. RESULTS: Using MR imaging, we found overall sensitivity and specificity for diagnosing ligament tears to be 94% and 99%, respectively, when no or one ligament was torn and 88% and 84%, respectively, when two or more supporting structures were torn. The difference in specificity was statistically significant (p < .0001). Sensitivity for diagnosing meniscal tears decreased as the number of injured structures increased, but the relationship achieved statistical significance (p = .001) only for the medial meniscus. For all categories of injury, MR imaging was more accurate than clinical evaluation, statistics for which were taken from the orthopedic literature. CONCLUSION: In knees with multiple ligament injuries, the diagnostic specificity of MR imaging for ligament tears decreases, as does the sensitivity for medial meniscal tears.