Does a titanium sleeve reduce the frequency of pseudotumors in metal-on-metal total hip arthroplasty at 5-7years follow-up?

INTRODUCTION

Little is known about pseudotumor frequency and risk factors for pseudotumor formation among different types of metal-on-metal (MoM) hip arthroplasties. A lower release of chromium and cobalt have been reported in MoM hip arthroplasties with a titanium sleeve compared to MoM designs without a titanium sleeve, but yet it is unknown whether a titanium sleeve reduces the pseudotumor frequency. We conducted a cross-sectional study to investigate: 1) pseudotumor frequency, 2) risk factors of pseudotumor formation 3) and correlations between pseudotumors, serum metal-ions, implant position, and clinical symptoms.

HYPOTHESIS

We expected a lower pseudotumor frequency in MoM hip articulation with a titanium sleeve than reported in MoM hip articulation designs using chromium-cobalt sleeve.

MATERIALS AND METHOD

A consecutive series of 41 patients/49 hips (31 males), mean age 52 (28-68) years, participated in a 5.5±0.5 (4-6.5) year follow-up study of their M2a_Magnum hip articulation (Biomet Inc., Warsaw, Indiana, USA). Patients were evaluated with magnetic resonance imaging (MRI), measurements of serum metal-ions, plain radiographs, and clinical outcome measures of Harris Hip Score (HHS) and Oxford Hip Score (OHS).

RESULTS

Eighteen of 47 hips (38%) had MRI-verified pseudotumors, all cystic, with a mean dimension of 10.6×25.6×41mm. Digital measurements on plain radiographs revealed a higher cup anteversion in patients with a pseudotumor of mean 28.4°±5.05° compared to mean 23.5°±6.5° in patients without a pseudotumor (P=0.009). Serum metal-ion concentrations, acetabular cup inclination and measures of HHS and OHS were similar between patients with and without a pseudotumor (P>0.46).

CONCLUSION

At 5.5±0.5years after surgery, MRI-verified cystic pseudotumors were frequently observed in M2a_Magnum hip articulations despite the use of titanium sleeves. The pseudotumors were related to high cup anteversion angles but not related to high serum metal-ions or clinical symptoms.

LEVEL OF EVIDENCE

IV: cross-sectional study.

Digital Radiography of the Spine, Large Bones and Joints Using Stimulable Phosphor

The value of digital radiography in musculoskeletal disorders was investigated by assessing its ability to depict anatomic structures and common radiologic features as compared with the conventional film-screen combination. The digital image that was frequency modified was superior to conventional films in delineating soft tissue structures and for areas with large attenuation differences. The conventional film-screen system was superior in depicting small anatomic structures and in identifying the zone close to prostheses. This was explained by the high spatial resolution of the conventional film system and the disturbing halo effect around the prosthesis seen with digital images. The halo effect is an overshoot caused by the unsharp masking operator, which was in this series not changed for individual examinations. The exposure (radiation dose) could be reduced to 50 per cent using the digital system, without any loss of information.

Conventional Radiography in Transient Synovitis of the Hip in Children

Conventional radiography was performed at diagnosis and at follow-up 5 to 9 months later in 70 children with transient synovitis of the hip. Twenty-four of the patients also had CT examination at diagnosis. The cartilaginous and osseous reaction in the conventional antero-posterior radiographs was studied as was the relation between the radiographic and CT findings concerning fat planes, joint effusion, and position of the hip joint. At diagnosis there was significant increase in the medial joint space and at follow-up examination there was significant increase in medial and cranial joint space, metaphyseal width and acetabular roof width. There was a correlation of a bulging lateral ‘capsular fat plane’ to the position of abduction in the affected hip which explains the asymmetry in the lateral fat plane observed in these patients.

Pitfalls in Ultrasonography of Hip Joint Synovitis in the Child

The normal and abnormal anatomy of the hip joint in childhood was evaluated by ultrasonography (US) with reference to examination technique and errors. When compared with computed tomography (CT), it was confirmed that the two sonographic echoes from the hip joint represent the femoral neck and the external surface of the capsule and that the thickness of the echo received from the capsule depends on the frequency of the transducer. Partial volume effects may simulate or increase the sonographic appearance of hip joint effusion. The normal relationship between joint capsule and femoral neck was established.

Computed Tomography of Humeral Head Cup Arthroplasties

Computed tomography (CT) was employed to evaluate resurfacing metal cup arthroplasties, in shoulders affected by rheumatoid arthritis. Reconstruction of the information obtained, with the high frequency filter, resulted in an image of the cement and skeletal structures inside the cup. This new application of CT may prove valuable in assessing the complications and results of cup arthroplasties.

The Vertical Position of the Patella

Patella height was defined by the distance between the midpoint of the articular surface of the patella and the condylar plane, which was constructed perpendicular to the mechanical axis of the tibia. In two series of normal individuals the measured distances were related to body height and the length of the lower leg and thus expressed as its ratio, which was the same in both sexes. The measurements were performed on lateral radiographs of the knee and lower leg obtained in weight-bearing and 30° to 40° of knee flexion using a simple device to obtain a standardized position of the lower leg during the examination. The standing position is proposed for these measurements since the patellar ligament is shorter in the recumbent position. The method can be used for biomechanical analysis of the femoropatellar joint.

Lesion of the Anterior Cruciate Ligament and Sagittal Disalignment of the Knee in Weight-Bearing

Twenty-nine patients with late reconstructive surgery for anterior cruciate ligament lesions had a clinical and radiologic follow-up ten years after injury. Anterior sagittal displacement of the tibia was recorded on the routine standing radiographs in 16 knees all having a normal femoro-tibial alignment in the non-weight-bearing position. Five of eleven patients with sagittal displacement of between 10 and 19 mm had early osteoarthrosis, which was confirmed by magnetic resonance imaging in four cases; their ages ranged from 23 to 38 years. No radiographic signs of osteoarthrosis were observed in those with displacements of less than 10 mm. In some patients there was a discrepancy between the clinical and radiographic measurements of instability. In addition to the clinical tests of instability standing rather than non-weight-bearing lateral radiographs are suggested for the routine assessment of cruciate ligament injuries.

Radiography and Scintigraphy in the Assessment of Early Gonarthrosis

The radiographic and scintigraphic appearances in early gonarthrosis were compared in 62 knees. Early femorotibial osteoarthrosis was found to be confined to one compartment (medial or lateral) of the joint. However, concomitant patellofemoral osteoarthrosis was common. 99Tcm-MDP scintigraphy was consistently positive when the joint space (femorotibial and patellofemoral) was reduced by 75 per cent or more. Joint space narrowing by as much as 50 per cent could be observed in a scintigraphically normal knee. The inconsistency between the radiologic and scintigraphic findings in the earliest stages of gonarthrosis points to the importance of appropriate radiographic technique.

Posttraumatic Osteolysis of the Pubic Bone Simulating Malignancy

Posttraumatic osteolysis (PO) of the os pubis is a diagnostic entity characterized at radiography by rapidly progressing destructive changes in fractures of the pubic body or rami. Fourteen patients with PO are here reported of whom in 8 the radiographic course of the condition was followed. They were all post-menopausal women and 7 were predisposed to osteopenia. The primary fractures were related to mild trauma in 7 patients and 7 had insufficiency fractures. Four patients had bilateral symmetrical PO. All 14 patients had concomitant insufficiency fractures of the sacrum observed at radiography, CT, scintigraphy or MR, probably due to pelvic instability caused by the PO of the os pubis. Symptoms of the sacral fractures usually dominated the clinical condition. Bony healing of the PO did not occur in any of the patients, but in all 8 patients followed radiographically, the fractures of the sacrum healed clinically and at CT. Knowledge about the condition is important to avoid unnecessary biopsy of the PO considered a metastatic lesion and/or extensive diagnostic search for a primary tumor.

Femoral Head Shape in Legg-Calvé-Perthes Disease

Twenty-three children with Legg-Calvé-Perthes disease were examined to determine the femoral head shape. We evaluated and correlated conventional radiography, arthrography and MR imaging. In the a.p. view, measurements were obtained from the center of the femoral head along the bony or cartilaginous outline at 30° intervals. Maximum flattening of the cartilaginous outline appeared laterally, 60° from the center of the baseline of the epiphyseal index and the caput index. Maximum flattening of the bony outline was found at 75°. Arthrography and MR imaging gave the same information about the shape of the femoral head cartilage. The bony femoral head shape on conventional radiographs in the a.p. view did not reflect the cartilage shape obtained by MR and arthrography.

Assessment AT CT of the Rheumatoid Shoulder with Surgical Correlation

Eleven shoulders in 10 patients with rheumatoid arthritis were examined by conventional radiography and CT prior to cup hemiarthroplasty of the humeral head and the results were compared with the surgical findings. There was good agreement between preoperative CT and surgical findings. Humeral head cavities and erosions, with cortical boundaries, could be seen more accurately at CT than at conventional radiography. The HU of their contents corresponded to those of soft tissue, being granulomatous in nature at surgery. In 8 humeral heads CT disclosed large areas of fatty degeneration of bone marrow with HU between − 10 HU and − 76 HU that were not visible on the conventional radiographs. These “fatty cysts” had no cortical boundaries, unlike inflammatory granulomas, but both lesions may influence the surgical approach to hemiarthroplasty.

MRI abnormalities of sacroiliac joints in early spondylarthropathy: a 1-year follow-up study

OBJECTIVE

To describe changes in chronic and acute magnetic resonance imaging (MRI) abnormalities of the sacroiliac joints (SIJs) in early spondylarthropathy (SpA), and to associate these findings with computed tomography (CT), X-ray, and clinical findings during a 1-year follow-up.

METHODS

Thirty-four patients, 20 males and 14 females, median age 27 years, with inflammatory low back pain (median 23 months) were included. MRI, CT, and X-ray, as well as clinical and laboratory tests were performed. After a follow-up period of 1 year (median 377 days) the examinations were repeated, and the findings were correlated.

RESULTS

MRI and CT changes resulting from SIJ destruction increased significantly during follow-up, and the two modalities were significantly correlated. For the MRI findings of inflammatory activity, only bone marrow oedema decreased significantly. An increase in the Schober test was the only clinical examination that changed significantly.

CONCLUSION

In early SpA, MRI can detect significant inflammatory and destructive changes of the SIJs over a 1-year follow-up period, in spite of minimal changes in the clinical parameters. The MRI changes in inflammatory activity are not detectable by CT and X-ray examinations. Thus, MRI may be a sensitive method, without known risks, for early diagnosis and for following disease progression in SpA.

[Grading sacroiliitis with emphasis on MRT-imaging]

Cross-sectional imaging techniques play a decisive role in identification, localization, and characterization of alterations in the sacroiliac joint during the early stage of seronegative spondylarthropathy (SpA). Although several studies showed that the diagnostic capabilities of MRI and CT are superior to those of conventional radiography, they have not yet become established and accepted as methods for evaluating the grade of ankylosing spondylitis (AS) in contrast to conventional radiography. The lack of acceptance for MRI and/or CT methods for evaluating and grading changes in the sacroiliac joint makes it difficult to include the results of these procedures in classifying the grade of SpA. Moreover, grading the changes in the sacroilac joint in SpA with a method more sensitive than conventional radiography will be of prime importance in assessing treatment, e.g., the efficacy of new biological therapeutic agents directed against the tumor necrosis factor-alpha (TNF-alpha). An overview of the available grading methods is provided and MRI and CT techniques are presented.

Magnetic resonance imaging of sacroiliitis in early seronegative spondylarthropathy. Abnormalities correlated to clinical and laboratory findings

OBJECTIVE

To compare a new MRI scoring system of the sacroiliac joints (SIJs) in early spondylarthropathy (SpA) with clinical and laboratory parameters.

METHODS

Forty-one patients (24 males, 17 females) with a median age of 26 yr and a median duration of inflammatory low back pain of 19 months were included. They all fulfilled the ESSG-criteria for SpA. The patients were examined by MRI of the SIJs using a new scoring system. Clinical examinations, biochemical tests, functional score (BASFI), and pain score (BASDAI) were also performed.

RESULTS

95% of the patients had inflammation and/or destructive bone changes of the SIJs at MRI. No correlation was found between MRI pathology and clinical findings. MRI demonstrated significantly greater severity of both inflammation and destruction of the SIJs in HLA B27 positive patients than in the HLA B27 negative patients.

CONCLUSIONS

In patients with early SpA, MRI was able to detect inflammatory and destructive changes of the SIJs, but the changes were not associated to clinical findings. Our results suggest a role of MRI in the detection of early-stage sacroiliitis.

MR imaging of the normal sacroiliac joint with correlation to histology

OBJECTIVE

The microscopic study of the various components of joints provide a proper basis for understanding the nature of pathologic lesions to which they are subject and their imaging appearances. This study was designed to correlate MR imaging with a systematic histological study of the normal sacroiliac joint (SIJ), which to our knowledge is not available in the literature.

DESIGN AND PATIENTS

Five male cadavers, aged 20 to 45 years, and seven male and seven female volunteers, aged 23 to 44 years, were investigated with oblique transaxial and coronal MR imaging of the SIJs. A variety of sequences including pre- and post-contrast T1 fat-saturated studies in the volunteers were used. Cryosectioning was performed in six SIJs of the five cadavers and compared with the MR images for the microscopic joint anatomy and assessed for the presence of abnormalities resembling those associated with sacroiliitis.

RESULTS

Throughout the SIJ, the hyaline cartilage of the sacral bone and the proximal third of the hyaline iliac cartilage was strongly attached to the surrounding stabilizing ligaments, forming wide margins of fibrocartilage. In the distal one-third of the joint only, the margins of the iliac joint facet resemble that of a synovial joint, which include an inner capsule with synovial cells. The MR anatomy of the ventral and dorsal aspects of the SIJ was only adequately visualized at oblique transaxial MR imaging. No contrast enhancement occurred in the synovial tissue or in the cartilaginous joint space. The dorsal transition between the proximal 2/3 and distal 1/3 of the cartilaginous joint was at microscopy rich in anatomical and histological variants, including osseous clefts, cartilage and subchondral defects, and vascular connective tissue in the bone marrow. These were all recognized at oblique transaxial MR imaging and in coronal MR sectioning may resemble abnormalities. Otherwise, no erosions, bone marrow abnormalities, bone sclerosis or abnormal contrast enhancement occurred in the normal joints.

CONCLUSIONS

The SIJ should be classified anatomically as a symphysis with some characteristics of a synovial joint being confined to the distal cartilaginous portion at the iliac side. Coronal MR imaging does not allow assessment of normal anatomy, variants or abnormalities of the ventral and dorsal margins of the cartilaginous SIJ.

Imaging of sacroiliitis in early seronegative spondylarthropathy. Assessment of abnormalities by MR in comparison with radiography and CT

PURPOSE

To analyze the type and frequency of abnormalities of the sacroiliac joint (SIJ) in early seronegative spondylarthropathy (SpA) by MR in comparison with CT and radiography, assess the most appropriate MR sequences to be used, and introduce a new way of grading MR abnormalities of the SIJ.

MATERIAL AND METHODS

The SIJs of 41 patients with early SpA (median duration of inflammatory low back pain of 19 months) were evaluated by MR imaging using STIR, T1, T2, and T1 fat saturated (FS) sequences before and after i.v. Gd contrast medium followed by staging of abnormalities. The findings were compared with those obtained by CT and radiography.

RESULTS

MR and CT had equal efficacy superior to radiography in staging of erosions and osseous sclerosis. Only MR allowed visualization and grading of active inflammatory changes in the subchondral bone and surrounding ligaments in addition to bone marrow fatty accumulations. T2-weighted sequences did not contribute to assessment of sacroiliitis.

CONCLUSION

MR of the SIJs is reliable in its visualization of joint erosions in early SpA and allows differentiation between active and chronic sacroiliitis. We recommend the following sequences: semicoronal T1 and both semicoronal and semiaxial STIR. If these images are normal, the examination can be finished; otherwise additional semicoronal T1 FS before and after i.v. contrast has to be performed as well as semiaxial post-contrast T1 FS.

Imaging of sacroiliitis in early seronegative spondylarthropathy. Assessment of abnormalities by MR in comparison with radiography and CT

PURPOSE

To analyze the type and frequency of abnormalities of the sacroiliac joint (SIJ) in early seronegative spondylarthropathy (SpA) by MR in comparison with CT and radiography, assess the most appropriate MR sequences to be used, and introduce a new way of grading MR abnormalities of the SIJ.

MATERIAL AND METHODS

The SIJs of 41 patients with early SpA (median duration of inflammatory low back pain of 19 months) were evaluated by MR imaging using STIR, T1, T2, and T1 fat saturated (FS) sequences before and after i.v. Gd contrast medium followed by staging of abnormalities. The findings were compared with those obtained by CT and radiography.

RESULTS

MR and CT had equal efficacy superior to radiography in staging of erosions and osseous sclerosis. Only MR allowed visualization and grading of active inflammatory changes in the subchondral bone and surrounding ligaments in addition to bone marrow fatty accumulations. T2-weighted sequences did not contribute to assessment of sacroiliitis.

CONCLUSION

MR of the SIJs is reliable in its visualization of joint erosions in early SpA and allows differentiation between active and chronic sacroiliitis. We recommend the following sequences: semicoronal T1 and both semicoronal and semiaxial STIR. If these images are normal, the examination can be finished; otherwise additional semicoronal T1 FS before and after i.v. contrast has to be performed as well as semiaxial post-contrast T1 FS.

MRI of the plantar structures of the foot after falanga torture

Falanga is an ancient form of punishment or torture but is still commonly reported by our refugees. The late result of caning the heel and ball of the foot is a chronic painful condition with few clinical signs. The aim of the present study was to assess, by MRI, possible morphologic characteristics of the heel and ball of the foot, related to falanga and pain in correlation to clinical findings. Magnetic resonance imaging of the foot was obtained in 12 victims exposed to falanga torture and 9 healthy volunteers. Sagittal T1-weighted spin-echo images (TR 616-840 ms, TE 20 ms), T2-weighted spin-echo images (TR 1900 ms, TE 90 ms), and short tau inversion recovery (STIR) images (TR 1200 ms, TE 15 ms, TI 100 ms) were performed. The central portion of the plantar aponeurosis was generally significantly thicker in victims exposed to falanga torture as compared with that of controls (P < 0.05). In all except one of the victims, MRI demonstrated two layers of the thickened plantar aponeurosis: a deeper portion with normal homogeneous low signal intensity (SI) appearance, and a superficial layer with characteristic areas of mixed SI on both T1- and T2-weighted images. There were no signs of chronic muscular compartment syndromes, and the thickness of the plantar pad did not differ between the two groups. Magnetic resonance imaging may demonstrate morphologic characteristics of the plantar aponeurosis which may confirm falanga torture. Further imaging with more specific sequences is warranted to demonstrate the supposed injuries in the compartmental fat tissue chambers and the vascularity of the ball pad of the foot.

Synovitis in Legg-Calvé-Perthes disease. Evaluation with MR imaging in 84 hips

PURPOSE

To evaluate, by means of MR imaging, the degree and persistence of synovitis in the hip joint in Legg-Calvé-Perthes disease and to correlate the degree of synovitis with the degree of epiphyseal necrosis.

MATERIAL AND METHODS

A total of 170 MR images in 72 patients (84 hips) were examined. The T2-weighted MR images were taken in the coronal plane in order to evaluate the degree of synovitis in the hip joint.

RESULTS

MR revealed synovitis in all cases in the early phase of the disease. In Catterall group II, synovitis was discreet to moderate for up to 6 months after diagnosis. Hips with more severe necrosis, Catterall groups III and IV, had moderate or intense degrees of synovitis. There was a correlation between the degree of synovitis and the lateral pillar classification according to HERRING et al. Also, there was a good correlation between the extent of signal changes in the epiphysis on MR imaging and the degree of synovitis. There was no difference when signal changes were evaluated on T1- or T2-weighted images. Signs of synovitis could be seen for up to 30 months after diagnosis in Catterall group I hips, and in Catterall groups II and III for up to 36 months, and in 2 cases even longer. Some Catterall group IV hips had discreet or mild synovitis for 60 months or more, after diagnosis.

CONCLUSION

The degree of synovitis on MR imaging correlates to the extent of epiphyseal necrosis seen on radiographs or MR imaging as well as to the lateral pillar classification, i.e. to a poor clinical outcome. In Catterall group IV hips, synovitis can even persist for up to 60 months after diagnosis.

Measuring anteversion in the femoral neck from routine radiographs

PURPOSE

To describe a new method for measuring femoral neck anteversion (FNA) that requires only one lateral radiograph of the knee in addition to routine radiographs of the hip for evaluation of total hip replacement; and to compare the proposed method with FNA measurement by means of 3D CT.

MATERIAL AND METHODS

In 18 femoral specimens, radiographic examinations of the hip and knee, in three different rotational positions, and one CT examination were made, and the measurements of FNA were compared. Similarly, in 38 patients with 40 total hip replacements, measurements from routine radiographic examinations of the hip and knee and from CT examinations were compared. The accuracy and reproducibility of the FNA measurements produced by this proposed method were calculated.

RESULTS

Accuracy and reproducibility were 2 degree and 2 degree for the proposed method in the femoral specimen study, and accuracy was 4 degree in the hip patient study. The proposed method had a minor flaw that was caused almost solely by differences in knee size at inward rotation of the femur.

CONCLUSION

FNA measurement can be made from a routine radiographic examination of the hip and a lateral view of the knee. This method achieves an acceptable level of accuracy and reproducibility.

Magnetic resonance imaging and early remodeling of the femoral head after femoral varus osteotomy in Legg-Calvé-Perthes disease

We studied 21 children with Legg-Calvé-Perthes Disease with a prognostically poor development, including lateralization, poor containment, anterolateral flattering, and deformation of the femoral head, as evaluated on serial magnetic resonance (MR) imaging. These children were treated with proximal femoral varus derotation osteotomy. The sphericity of the cartilaginous and bony femoral epiphysis was evaluated postoperatively on serial radiography and MR imaging. There was an early postoperative continuous spherical remodeling over a follow-up period of 3.0 years (1.0-5.1; SD, 1.3).

Epiphyseal bone-marrow abnormalities and restitution in Legg-Calvé-Perthes disease. Evaluation by MR imaging in 86 cases

PURPOSE

By means of MR imaging, to determine signal abnormalities in the femoral epiphysis; to determine their location, extent and restitution over time; and to correlate these findings to the Catterall radiological classification.

MATERIAL AND METHODS

A total of 247 MR images in 86 patients (101 hips) with Legg-Calvé-Perthes disease were examined. The MR images were taken in the coronal plane, and the images through the center of the femoral head were used for this study.

RESULTS

T1-weighted images proved as good as T2-weighted images for the MR evaluation of the extent of the necrosis. In almost every case, the central-cranial part of the epiphysis showed a low initial signal. In Catterall group I, the medial part was never involved. In Catterall III and IV, almost the entire epiphysis showed signal changes. In the period 3-6 years after diagnosis, we still found signal changes in the epiphysis in some hips but there was no correlation with the Catterall classification. After 6 years, the epiphysis showed normal signal intensity in MR imaging. In T1-weighted images, Gd-enhancement occurred in the peripheral regions in the early stages of the disease. The central part of the epiphysis became more enhanced over time and peaked in the period 1-3 years after diagnosis.

CONCLUSION

MR is a valuable modality for monitoring changes in the femoral epiphysis. We propose a new classification of the extent and pattern of epiphyseal bone-marrow abnormalities based on the 4 zones most commonly observed in MR imaging.

Metaphyseal histology and magnetic resonance imaging in Legg-Calvé-Perthes disease

Cylindrical biopsy specimens from the proximal femoral metaphysis were obtained in conjunction with surgery in 22 patients with Legg-Calvé-Perthes disease. The histopathological examination revealed fat necrosis, vascular proliferation, and focal fibrosis indicating previous episodes of ischemia. There was no correlation between the histopathological findings and the corresponding magnetic resonance images.

CT measurement of anteversion in the femoral neck. The influence of femur positioning

PURPOSE

To evaluate CT methods of measuring anteversion in the femoral neck with respect to measurement accuracy and with respect to the influence exerted by different femoral shaft positions; and to describe a new CT measurement concept that introduces a mathematical adjustment for different femoral shaft positions. The new technique facilitates the taking of measurements in patients who cannot be correctly positioned in traditional methods.

MATERIAL AND METHODS

CT examinations of previously measured anteversions in the femoral neck were reviewed in retrospect in 30 patients with fractures of the femoral neck. The position of the femoral shaft was assessed. A reference angle was compared with direct traditional measurements and with measurements adjusted for the actual position of the femoral shaft by means of a 3D mathematical reconstruction. Reproducibility and inter- and intraobserver variability were assessed in 10 cases.

RESULTS

All femurs varied in position within the gantry. The mean difference between the direct CT measurement and the adjusted CT measurement compared to the reference angle were -8.8 degrees (range -35.0-16.3 degrees) and -0.1 degrees (range -1.4-1.4 degrees), respectively. For the adjusted CT method, reproducibility and inter- and intraobserver variability were 1.4 degrees, 1.6 degrees and 1.4 degrees (SD of difference), respectively.

CONCLUSION

CT measurement of femoral anteversion in clinical practice can only be accurate when corrected for variation in the position of the femoral shaft.

MRI in chronic recurrent multifocal osteomyelitis

OBJECTIVE

To review our experience of chronic recurrent multifocal osteomyelitis (CRMO) and to assess the value of MRI in this rare disease, which mainly affects children and adolescents.

DESIGN AND PATIENTS

Seventeen patients from our departments were reviewed. All underwent conventional radiography and MRI, and most had bone scintigraphy. All had undergone bone biopsy, with microbiological and histopathological examinations, to exclude infectious disease, tumours and tumour-like lesions.

RESULTS AND CONCLUSION

CRMO affects predominantly the tubular bones of the limbs, followed by the clavicle and the spine. Other locations are rare. Diagnosis is important in avoiding unnecessary diagnostic procedures and to initiate appropriate therapy, and is usually based on a characteristic course and the appearances on radiography. However, CRMO lesions of tubular bones and the spine exhibit quite characteristic MRI features which support the diagnosis, while the appearance of the early clavicular lesion is non-specific. At all sites of CRMO in the skeleton, MRI is valuable in assessing the extent and activity of the lesion. It may exclude pyogenic involvement of the bone and soft tissues and guide effective biopsy.

[Magnetic resonance imaging of the knee joint after trauma with intra-articular accentuation]

Two male adolescents with direct trauma to the knee and haemarthrosis were followed up with MR imaging (MAI). No fractures were detected on plain films and both patients had extensive bone marrow lesions in MRI. The lesions were located within the metaphysis and the lateral tibial and femoral condyle respectively. In one patient MRI demonstrated additional soft tissue lesions of the femoral muscles. One patient had almost no clinical symptoms, while the other patient suffered from severe pain, inability to walk, and delayed recovery. The present report emphasizes the potential of MRI for the detection of occult injuries of bone and soft tissue, and calls for prospective studies of their clinical significance.

The effect of arthrocentesis in transient synovitis of the hip in the child: a longitudinal sonographic study

Twenty-one children with transient synovitis of the hip were treated in two consecutive groups. In 12 patients aspiration of the synovial effusion was performed within 24 h of admission. In a second group of nine patients no aspiration was performed. There was no other difference in treatment. Joint effusion was studied sonographically in comparison with the nonsymptomatic contralateral hip. Sonography was performed immediately after admission, within 12 h after aspiration, and repeatedly during a follow-up period of up to 15 days. Following aspiration the capsular distention decreased to 49% but recurred within 24 h to 72% of the preoperative value. However, during the first 4 days of follow-up the capsular distention in the aspirated cases was significantly and permanently lower than in the nonaspirated cases. We conclude that arthrocentesis in the acute stage of transient synovitis of the hip in the child permanently reduces the intracapsular effusion.

Fatigue fracture of the sacral bone associated with septic arthritis of the symphysis pubis

Fractures of the pubic rami are almost invariably associated with fractures of the posterior arch of the pelvic ring. Two women, aged 50 and 67 years, with septic arthritis of the symphysis pubis attended by severe low back pain, were followed with CT and MR imaging of the pelvis, as well as bond scintigraphy in one patient. In the first patient sacral fractures with severe displacement were revealed, prompting stabilizing symphysiodesis. In the second patient an undisplaced fatigue fracture was confirmed in the right half of the sacrum. In patients with pelvic laxity following arthritis of the symphysis and post-traumatic osteolysis associated with low back pain, displaced or occult fractures of the bones adjacent to the sacroiliac joints should be considered.

Subsidence of tibial components in knee arthroplasty. A comparison between conventional radiography and roentgen stereophotogrammetry

RATIONALE AND OBJECTIVES

To assess the ability of conventional radiography to identify subsidence of tibial components.

METHODS

Forty-three cases of knee arthroplasty were followed for 4 years using roentgen stereophotogrammetric analysis as the gold standard.

RESULTS

Roentgen stereophotogrammetric analysis showed subsidence in all uncemented prostheses, whereas two thirds of the cemented prostheses subsided. Medially, the sensitivity of conventional radiography was low, 25%, whereas the specificity was 83%. For the other regions, the sensitivity was almost 100%, although the specificity was as low as 66% frontally and dorsally.

CONCLUSIONS

Medially, where most prostheses were inserted with a slight overhang, conventional radiography identified subsidence correctly. Laterally, frontally, and dorsally, however, conventional radiography overestimated the subsidence by a factor of 2 to 3. This error was caused by bony protrusions arising in the cranial direction from the uncovered bone surfaces, thus changing the points of reference. This problem arose more commonly in uncemented cases, whereas cement seemed to seal the bone.

Sonography and intracapsular pressure in Perthes' disease. 39 children examined 2-36 months after onset

39 children with Legg-Calvé-Perthes Disease (LCPD) and with a radiographically unsatisfactory development were examined with sonography regarding synovitis and with intracapsular pressure recording and aspiration performed 15 (2-36) months after the onset of symptoms. The mean anterior sonographic capsular distension was 3.0 (1.0-7.0) mm greater than that of the contralateral, asymptomatic hip. The mean intracapsular pressure was 4.5 (0-11.5) kPa with the hips in extension and neutral rotation, 9.7 (1.3-27.3) kPa with the hips in extension and inward rotation and 0.9 (-0.8-4.7) kPa in 45 degrees of flexion. We conclude that these children have synovitis as diagnosed sonographically. This synovitis is probably symptomatically and prognostically important in LCPD due to increased intracapsular pressure, with pain, a decreased range of motion and, potential joint contracture.

Femoral head shape in Legg-Calvé-Perthes disease. Correlation between conventional radiography, arthrography and MR imaging

Twenty-three children with Legg-Calvé-Perthes disease were examined to determine the femoral head shape. We evaluated and correlated conventional radiography, arthrography and MR imaging. In the a.p. view, measurements were obtained from the center of the femoral head along the bony or cartilaginous outline at 30 degrees intervals. Maximum flattening of the cartilaginous outline appeared laterally, 60 degrees from the center of the baseline of the epiphyseal index and the caput index. Maximum flattening of the bony outline was found at 75 degrees. Arthrography and MR imaging gave the same information about the shape of the femoral head cartilage. The bony femoral head shape on conventional radiographs in the a.p. view did not reflect the cartilage shape obtained by MR and arthrography.

Assessment at CT of the rheumatoid shoulder with surgical correlation

Eleven shoulders in 10 patients with rheumatoid arthritis were examined by conventional radiography and CT prior to cup hemiarthroplasty of the humeral head and the results were compared with the surgical findings. There was good agreement between preoperative CT and surgical findings. Humeral head cavities and erosions, with cortical boundaries, could be seen more accurately at CT than at conventional radiography. The HU of their contents corresponded to those of soft tissue, being granulomatous in nature at surgery. In 8 humeral heads CT disclosed large areas of fatty degeneration of bone marrow with HU between -10 HU and -76 HU that were not visible on the conventional radiographs. These "fatty cysts" had no cortical boundaries, unlike inflammatory granulomas, but both lesions may influence the surgical approach to hemiarthroplasty.

Effect of radiographic contrast media on granulocyte phagocytosis of Escherichia coli in a whole blood flow cytometric assay

RATIONALE AND OBJECTIVES

Earlier studies have demonstrated an adverse effect of radiographic contrast media (CM) on granulocyte phagocytosis. Most studies in the past have depended on granulocyte separative procedures that may themselves affect granulocyte functions. This study was performed to evaluate the effect of CM on phagocytosis using a flow cytometric assay allowing more physiological assay conditions.

METHODS

Twenty consecutive patients were blindly randomized to receive the nonionic ratio 3.0 CM iohexol or the ionic ratio 3.0 CM ioxaglate for intravenous urography. Granulocyte phagocytic potential was measured before and at 1, 5, and 20 minutes after CM administration with a flow cytometric whole blood method evaluating the ingestion of complement- and immunoglobulin G (IgG)-opsonized fluorescent Escherichia Coli bacteria.

RESULTS

The ability of granulocytes to phagocytize opsonized E. Coli was adversely affected by both CM used. Compared with baseline values, significantly decreased phagocytic activity was observed for iohexol at 1, 5, and 20 minutes and for ioxaglate at 1 and 5 minutes. The largest decrease with ioxaglate was from 85.3 +/- 10.5 to 69.3 +/- 16.3 (5 minutes), and the largest change with iohexol was from 87.1 +/- 8.5 to 74.5 +/- 15.9 (5 minutes).

CONCLUSION

These results confirm earlier reports that ionic and nonionic CM adversely affect the phagocytic ability of granulocytes after intravenous administration.

Posttraumatic osteolysis of the pubic bone simulating malignancy

Posttraumatic osteolysis (PO) of the os pubis is a diagnostic entity characterized at radiography by rapidly progressing destructive changes in fractures of the pubic body or rami. Fourteen patients with PO are here reported of whom in 8 the radiographic course of the condition was followed. They were all post-menopausal women and 7 were predisposed to osteopenia. The primary fractures were related to mild trauma in 7 patients and 7 had insufficiency fractures. Four patients had bilateral symmetrical PO. All 14 patients had concomitant insufficiency fractures of the sacrum observed at radiography, CT, scintigraphy or MR, probably due to pelvic instability caused by the PO of the os pubis. Symptoms of the sacral fractures usually dominated the clinical condition. Bony healing of the PO did not occur in any of the patients, but in all 8 patients followed radiographically, the fractures of the sacrum healed clinically and at CT. Knowledge about the condition is important to avoid unnecessary biopsy of the PO considered a metastatic lesion and/or extensive diagnostic search for a primary tumor.

Comparison of symptomatic versus nonsymptomatic patients with chronic anterior cruciate ligament insufficiency. Radiographic sagittal displacement during weightbearing

The sagittal anterior displacement of the tibia, induced by weightbearing, in chronic anterior cruciate ligament-insufficient knees was measured radiographically in 2 groups of patients. All patients in both groups had an increased laxity when assessed with the Lachman and flexion-rotation-drawer test. Sixteen patients were functionally improved and were relatively asymptomatic after a neuromuscular rehabilitation program, while the second group consisted of another 16 patients with persistent functional instability, despite the same rehabilitation program, who eventually had ligament reconstruction. The mean radiographic anterior displacement during weightbearing in the nonsymptomatic group was 4.3 mm, and 8 patients had a displacement < or = 2 mm. In the symptomatic group, the corresponding value was 8.1 mm (P < 0.05), and 3 patients had a displacement < or = 2 mm. No correlations to meniscal injuries, age, or time from injury were found between the patients having a displacement >2 mm and those with < or = 2 mm. The findings should be explained by differences in neuromuscular control of the increased laxity in the injured knee.