强直性脊柱炎髋关节改变的X线、CT和MRI对比研究

目的 探讨强直性脊柱炎(AS)髋关节受累的影像表现,比较X线平片、CT和MRI显示AS髋关节受累的敏感度.方法 对55例AS患者行骨盆X线平片和MR检查,其中29例行髋关节CT检查.MR平扫均包括冠状面T1WI、T2WI、STIR、附加水激励的三维稳态快速梯度回波序列(3D-BTFE-WATS),其中24例同时行脂肪抑制T1WI增强检查.分析患者的影像资料,应用x2检验对X线平片、CT和MRI显示AS髋关节受累改变的敏感度进行分析.结果 55例AS患者110侧髋关节中,X线平片和MRI显示异常分别为13侧和85侧;X线平片改变包括关节面下骨侵蚀破坏13侧、关节间隙变窄4侧、韧带骨赘5侧;MRI显示关节面下骨侵蚀破坏31侧、关节间隙变窄4侧、关节少量积液80侧、骨髓水肿32侧、脂肪沉积28侧、韧带附着点炎21侧,24例行MR增强检查患者中19例见双侧滑膜异常强化.CT检查29例共58侧髋关节,CT在显示X线平片和MRI所显示的骨破坏同时,发现X线平片未能显示的10侧骨破坏和MRI未显示的1侧骨破坏.X线平片、CT、MRI显示异常分别为10.3％ (6/58)、27.6％ (16/58)和77.6％ (45/58),MRI显示髋关节受累的敏感度优于X线平片和CT(x2值分别为53.22和29.08,P值均＜0.05).MRI除显示X线平片和CT所能显示的慢性骨结构改变外,还发现X线平片和CT未能显示的急性炎症改变.结论 MRI能显示X线平片和CT不能显示的AS髋关节受累的急性炎症改变,滑膜炎所致的少量积液和滑膜异常强化是髋关节受累最常见的MRI表现.     

Bone SPECT is more sensitive than MRI in the detection of early osteonecrosis of the femoral head after renal transplantation.

We compared the diagnostic sensitivity of (99m)Tc-methylene diphosphonate bone SPECT and MRI in the early detection of femoral head osteonecrosis after renal transplantation. METHODS: The patients were 24 renal allograft recipients who underwent both bone SPECT and MRI within 1 mo of each other because of hip pain but normal findings on plain radiography. SPECT was considered positive for osteonecrosis when a cold defect was detected in the femoral head, and the defect was further classified according to the presence of adjacent increased uptake: type 1 = a cold defect with no adjacent increased uptake; type 2 = a cold defect with adjacent increased uptake. MRI was considered positive for osteonecrosis when a focal region with low signal intensity on T1 images was detected in the femoral head. Final diagnoses were made by surgical pathology or clinical and radiologic follow-up of >1 y. RESULTS: A total of 32 femoral heads, including 24 of 29 painful hips and 8 of 19 asymptomatic contralateral hips, were confirmed as having osteonecrosis. SPECT detected osteonecrosis in all 32 of the femoral heads, resulting in a sensitivity of 100% (32/32), whereas MRI detected osteonecrosis in 21 femoral heads, for a sensitivity of 66% (21/32, P < 0.005). SPECT showed the type 1 pattern in 13 and the type 2 in 19. Ten of the 13 femoral heads with the type 1 pattern were false-negative on MRI, whereas only 1 of 19 with the type 2 pattern was normal on MRI (P < 0.001). There were 6 femoral heads with normal MRI findings and abnormal SPECT findings (type 1 pattern) in 3 patients, for whom hip pain decreased and radiographic findings were normal during follow-up. Follow-up bone SPECT showed a decreasing area of cold defect in 4 femoral heads. CONCLUSION: (99m)Tc-methylene diphosphonate SPECT is more sensitive than MRI for the detection of femoral head osteonecrosis in renal transplant recipients. Bone scintigraphy with SPECT is needed to diagnose osteonecrosis in patients with hip pain despite normal radiography results after renal transplantation. The significance of a transient SPECT abnormality needs to be clarified by further natural history studies.     

Correlation of MRI findings with clinical findings of trochanteric pain syndrome

OBJECTIVE: Greater trochanter pain syndrome due to tendinopathy or bursitis is a common cause of hip pain. The previously reported magnetic resonance (MR) findings of trochanteric tendinopathy and bursitis are peritrochanteric fluid and abductor tendon abnormality. We have often noted peritrochanteric high T2 signal in patients without trochanteric symptoms. The purpose of this study was to determine whether the MR findings of peritrochanteric fluid or hip abductor tendon pathology correlate with trochanteric pain. MATERIALS AND METHODS: We retrospectively reviewed 131 consecutive MR examinations of the pelvis (256 hips) for T2 peritrochanteric signal and abductor tendon abnormalities without knowledge of the clinical symptoms. Any T2 peritrochanteric abnormality was characterized by size as tiny, small, medium, or large; by morphology as feathery, crescentic, or round; and by location as bursal or intratendinous. The clinical symptoms of hip pain and trochanteric pain were compared to the MR findings on coronal, sagittal, and axial T2 sequences using chi-square or Fisher's exact test with significance assigned as p < 0.05. RESULTS: Clinical symptoms of trochanteric pain syndrome were present in only 16 of the 256 hips. All 16 hips with trochanteric pain and 212 (88%) of 240 without trochanteric pain had peritrochanteric abnormalities (p = 0.15). Eighty-eight percent of hips with trochanteric symptoms had gluteus tendinopathy while 50% of those without symptoms had such findings (p = 0.004). Other than tendinopathy, there was no statistically significant difference between hips with or without trochanteric symptoms and the presence of peritrochanteric T2 abnormality, its size or shape, and the presence of gluteus medius or minimus partial thickness tears. CONCLUSIONS: Patients with trochanteric pain syndrome always have peritrochanteric T2 abnormalities and are significantly more likely to have abductor tendinopathy on magnetic resonance imaging (MRI). However, although the absence of peritrochanteric T2 MR abnormalities makes trochanteric pain syndrome unlikely, detection of these abnormalities on MRI is a poor predictor of trochanteric pain syndrome as these findings are present in a high percentage of patients without trochanteric pain.     

Reliability of slice-encoding for metal artefact correction (SEMAC) MRI to identify prosthesis loosening in patients with painful total hip arthroplasty – a single centre,prospective, surgical validation study

Objectives:To validate reliability of slice-encoding for metal artefact correction (SEMAC)-MRI findings in prosthesis loosening detection by comparing them to surgical outcomes (gold standard) in symptomatic patients following hip arthroplasties. To evaluate periprosthetic anatomical structures in symptomatic patients to identify an alternative cause of hip symptoms.Methods:We prospectively followed 47 symptomatic patients (55 hips, 39 painful hips – group P and 16 control hips – group C) at our institution from 2011 to 2016. We acquired 1.5 T MRI conventional and SEMAC-MRI images for all patients. Two consultants scored MRI for osteolysis and marrow oedema zone-wise using predefined signal characteristics and settled scoring variations by consensus. We used Spearman Rank-Order Correlation for correlation analysis and used OMERACT (Outcome Measures in Rheumatology) filter pillars to validate SEMAC-MRI findings.Results:Eleven patients needed revision surgery, all from group P. None from group C required revision surgery. Remaining 28 hips in the group P were managed conservatively pain completely resolved in 21 hips, eight hips had trochanteric bursitis, eight had extraarticular cause and the remaining five hips had spontaneous pain resolution. We found moderate-to-weak correlation between SEMAC-MRI findings for prosthesis loosening and revision surgery outcomes. Sensitivity, Specificity, PPV and NPV in Group P were (72.7, 64.3, 44.4, 85.7%) in T1W-SEMAC, (90.9, 46.4, 40.0, 92.9%) in STIR-SEMAC and (36.3, 78.5, 40.0, 75.8%) in PDW-SEMAC.Conclusion:Negative SEMAC-MRI results can effectively exclude prosthesis loosening confirmed on revision surgery and SEMAC-MRI can detect alternative cause of hip pain accurately.Advances in knowledge:Negative SEMAC-MRI in painful THA patients can effectively exclude prosthesis loosening as a cause.     

Magnetic resonance imaging of osteonecrosis in divers: comparison with plain radiographs

Objective. To assess the diagnostic value of magnetic resonance imaging (MRI) as compared with radiographic findings in osteonecrosis in divers. Design and patients. MRI scans and conventional radiographs of the shoulder, hip and knee joints of 23 professional male scuba divers were reviewed together with their clinical findings and personal histories. Correlations between the MRI findings and the radiographic evaluation, clinical symptoms, and personal history were then investigated. Results and conclusions. Lesions found on MRI in 23 divers included 27 in 39 proximal humeri, 17 in 36 proximal femora, 13 in 32 distal femora, and 12 in 32 proximal tibiae. Diffuse, marginated, or irregular patterns were observed. No lesions were seen in epiphyses of the distal femur or proximal tibia. We tried to classify these MRI findings by location and appearance. MRI showed no patients with only one affected bone. A close correlation between the MRI findings and maximum diving depth was observed in the proximal humerus. MRI depicted bone lesions that could not be detected on the radiographs. A routine MRI investigation of the hip joints should be performed in every diver in whom osteonecrosis is diagnosed at another site, for early detection of femoral head osteonecrosis. MRI of the shoulder joint is also the best surveillance in divers who dive deeper than 15?m.     

正常人和股骨头缺血性坏死的髋关节腔液体的MRI

目的 探讨正常人和股骨头缺血性坏死的髋关节腔液体的ＭＲＩ。材料与方法 ２５２个正常人及３１个股头缺血性坏死的髋关节。所有病例均作ＳＥ序列Ｔ１、Ｔ２加权,黄断位及冠状位扫描。所有股骨头缺血性坏死的髋关节加作冠状位脂肪抑制序列。结果 关节腔液体于Ｔ２加权和脂肪抑制序列冠状位扫描显示最清楚。于以上两个序列上,关节腔液一现比脂肪高的信号。关节腔液体分４级：０级,无液体;１级,少量液体;２级,液体达骨头周围     

MRI of early symptomatic metal-on-metal total hip arthroplasty: a retrospective review of radiological findings in 20 hips

AIM: To perform a retrospective review of all the conventional radiographic and magnetic resonance imaging (MRI) studies performed in patients with early postoperative pain following cobalt-chrome metal-on-metal total hip arthroplasty. METHODS: A retrospective review of the radiology, surgical findings and histology in nineteen patients who had undergone a total of 20 hip arthroplasties using a cobalt-chromium on cobalt-chromium alloy prosthesis was undertaken. RESULTS: Measures of implant placement on the immediate postoperative radiographs were all within the normal ranges (n=20). Where more than one postoperative radiograph was available statistical analysis revealed no evidence of progressive change before the MRI examination (14). The median postoperative time to MRI was 35 months (range 11-63 months). Abnormalities were demonstrated using MRI in all symptomatic hips (n=20). These comprised: periprosthetic fluid collections (20), which were isointense to muscle on T1-weighted images in 19 cases and hyperintense on T2-weighted images in 18 cases, periprosthetic bone marrow oedema (n=6), muscle oedema (n=4), avulsion of the gluteus minimus and medius tendons (n=5), atrophy of piriformis (n=15) and obturator internus (n=17), and fracture of the medial calcar (n=1). Operative findings in patients who had undergone revision surgery (n=15) included: fluid-filled cavities (n=11), soft tissue necrosis (n=8), gluteal tendon avulsion (n=5), proximal femoral diaphyseal necrosis (n=4), and pitting and corrosion of the femoral stems (n=8), which were, in all cases, firmly fixed to the cement mantle. Histology revealed viable tissue in six hips with necrosis (n=12) and fibrin deposition (n=15) being the predominate findings. Other findings included a perivascular lymphocytic infiltrate (n=5), features of active inflammation (n=4), and metallosis (n=1). CONCLUSION: A significant number of patients with metal-on-metal hip replacements presented with early postoperative pain because of an abnormal soft-tissue reaction. MRI can demonstrate characteristic soft-tissue disease in these patients where conventional radiographs are frequently normal.     

MR imaging findings in transient osteoporosis of the hip

Purpose: The authors sought to describe the magnetic resonance (MR) imaging findings including perfusion imaging, in association with the course of acute bone marrow oedema syndrome (aBMEs), in a group of patients with acute hip pain and a final diagnosis of transient osteoporosis of the hip (TOH). Materials and methods: From 217 patients referred with a probable diagnosis of avascular necrosis (AVN) of the femoral head, we identified 42 patients who had clinical and radiographic findings not relevant to AVN. MR imaging examinations were performed on a 1.0T scanner. Perfusion imaging was performed in 20 patients. The bone marrow oedema (BME) was classified in four stages. In addition, the presence or absence of oedema in the subchondral area and the presence of other subchondral lesions were recorded. Acetabular bone marrow was also assessed for the presence of oedema. The quantitative measurements included: maximum size of the effusion, percentage of enhancement (PE) and time of peak enhancement of abnormal marrow compared to the first pass, on the perfusion images. Results: Osteopenia was present on plain radiographs in 87% of cases. The most common pattern of BME was extending to the femoral head and neck. Acetabulum was involved in 16.6%. In 22.6% the BME spared the subchondral region of the femoral head. There were two cases (4.7%) with subchondral changes. A joint effusion was noted in 33 of the 42 patients. On perfusion imaging, a delayed peak enhancement was noted in 20 patients between 40 and 65 s after the first pass of contrast. No patient had any evidence of femoral head collapse or change in sphericity on follow-up MRI. None of the patients developed avascular necrosis in a time frame of 18 months from the onset of the acute hip pain. Conclusion: The aBMEs MR imaging pattern varies and is most commonly appearing on X-rays as osteopenia. Absence of subcondral lesions, delayed peak enhancement of the abnormal marrow on perfusion images, and sparing of subchondral zone from marrow oedema are MR imaging findings highly correlated to TOH.     

The application of MR imaging in the detection of hip involvement in patients with ankylosing spondylitis

Objective

To investigate the changes in hip MR imaging, evaluate the frequency of hip involvement and compare the value of clinical symptoms, radiographs, and MR imaging in the detection of hip involvement in patients with ankylosing spondylitis (AS).

Methods

Anteroposterior radiographs of the pelvis, MR imaging of the hip and clinical evaluation were undertaken in 58 patients with definite AS. All patients were followed up 3 years. Annual radiographs and clinical evaluation were carried out. The imaging data were independently assessed by two experienced radiologists who were blinded to patient identity and clinical characteristics. Based on the Bath Ankylosing Spondylitis Radiology Hip Index (BASRI-hip) scoring system, BASRI-hip scores ≥2 were defined as radiological hip involvement. On MR imaging, both acute and chronic inflammatory changes were considered positive signs for hip involvement. Symptomatic hip involvement was defined as current or past pain or limitation of the hip movement. The statistical analysis was performed using the χ² test for comparison of sensitivity among clinical symptoms, radiographs, and MR imaging in the detection of hip involvement and the Student's t-test for comparison of disease duration between with and without hip involvement. A P value <0.05 was considered to be statistically significant. For interpreting MRI and radiographs, the percentage of agreement between the two assessors and the kappa coefficients were calculated.

Results

On MR imaging, positive changes were detected in 86 (74.1%) hips among 116 hips in all 58 patients. Joint effusion was observed in 73 (62.9%) hips; 23 out of 27 patients who underwent fat-saturated contrast-enhanced T₁-weighted sequences had abnormal synovial enhancement in bilateral hips. The other abnormal MR findings included subchondral bone marrow edema in 35 (30.2%) hips, enthesitis in 22 (19.0%) hips, fatty accumulation of the bone marrow in 28 (24.1%) hips, bone erosive destruction in 32 (27.6%) hips, and joint-space narrowing in 4 (3.4%) hips. Based on the BASRI-hip scoring system, 68, 24, 18, 6 and 0 hips had no, suspicious, mild, moderate or severe damage on conventional radiographs of the pelvis, respectively. Thirty-five hips in 20 patients had current or past pain or limitation. The proportion of hip involvement according to MR imaging, radiographs, and clinical symptoms was 74.1% (86/116), 20.7% (24/116), and 30.2% (35/116), respectively. MR imaging yielded higher values than radiographs and clinical symptoms in the detection of hip involvement in patients with AS (χ² = 66.45 and 44.93, P <0.05). Interreader reliability for interpretation of findings was acceptable for both MRI and radiographs. During follow-up, radiological hip involvement were found in 10 hips with BASRI-hip scores ≤1 at baseline and clinical symptoms appeared in 15 sides of the original asymptomatic hip. On baseline MR imaging, inflammatory changes were seen in all hips which appeared symptoms and/or radiological involvement both at baseline and during follow-up.

Conclusion

The proportion of hip involvement is much higher than that suggested by radiographic changes and clinical symptoms. MR imaging is superior to conventional radiographs and clinical symptoms in the detection of hip involvement. Joint effusion and synovial enhancement caused by synovitis are the commonest hip findings on MR imaging in patients with AS.     

髋关节暂时性骨质疏松的MRI诊断及临床综合治疗观察

目的探讨髋关节暂时性骨质疏松的MRI表现及临床综合治疗。方法搜集经MRI检查、临床治疗证实的6例髋关节暂时性骨质疏松患者进行回顾性分析,男4例,女2例,平均年龄22岁,女性患病时未在妊娠期。全部患者患病髋关节均表现为不同程度的突发急性疼痛或渐进性疼痛。临床采用静注复方丹参和/或口服复方丹参等活血化淤,改善微循环的治疗方法。结果患侧髋关节MRI表现为片状等低T1、长T2异常信号,脂肪抑制序列呈高信号,增强扫描病灶无强化;临床治疗3个月后疼痛明显减轻,6个月疼痛完全缓解,复查MRI病变完全消失。结论MRI对诊断髋关节暂时性骨质疏松有一定价值。     

MRI of joint fluid in the normal and ischemic hip

MR images in 36 hips with documented avascular necrosis and 80 hips without evidence of joint disease were studied to determine the amount and appearance of fluid in the joint. All MRI examinations were done on a 1.5-T machine and included coronal images made with relative T2 weighting (repetition times = 2000-2500 msec, echo delays = 60-100 msec). The amount of joint fluid, which had an intense signal higher than fat, was graded from 0 to 3 and analyzed with respect to the patient's age and radiographic stage of avascular necrosis. Joint fluid was seen in 84% of presumed normal hips. Only four (5%) of 80 had enough fluid to surround the femoral neck (grade 2), and none had sufficient fluid to distend the joint capsule (grade 3). In comparison, 21 (58%) of 36 hips with avascular necrosis had grade-2 or grade-3 effusions (p less than 0.005), and some fluid was seen in all. Grade-3 effusions were seen in seven (50%) of 14 hips with flattening of the femoral head, compared with only one (5%) of 20 in which the femoral contour was normal. It is concluded that small amounts of fluid are present in both normal hips and those with avascular necrosis. In avascular necrosis, increased joint fluid may be present before radiographic abnormalities occur, but it is greatest after there is flattening of the femoral head. MRI is a highly sensitive method for detecting fluid in the hip joint.     

Radiologic manifestations of proximal-type epithelioid sarcoma of the soft tissues

OBJECTIVE: This study describes the MR imaging findings of focal osteochondral lesions found in the hips of 11 athletes with persistent pain and normal findings on radiographs. CONCLUSION: Osteochondral lesions of the femoral head are seen on MR imaging as focal, medial areas of high T2-weighted and low T1-weighted signals and should be considered as a possible cause of persistent hip or groin pain in young, high-level athletes because the institution of appropriate treatment may help to prevent late degenerative sequelae.     

MRI of the cartilaginous epiphysis of the femoral head in the piglet hip after ischemic damage

MRI of the cartilaginous epiphysis (CE) of piglet femoral head was performed after ischemic damage to study the changes in the CE found on MRI and to correlate these changes with histologic findings. Avascular necrosis of the femoral head was induced with a suture ligature in nine piglets; one piglet was killed postoperatively on day 3 and on weeks 1, 2, 3, 4, 6, 7, and 8 (two piglets were killed on week 3). MRI of the ischemic and contralateral nonischemic hip joints were obtained with a 60-mm field of view (low resolution MRI). Biopsy cores of the femoral heads were imaged with a 15-mm field of view (high resolution MRI) and correlated with histologic sections. The CE for all operated hips, except for the 3-day postoperative specimen, showed evidence of ischemic changes on histologic assessment; the severity of damage increased with time. The MRI appearance of ischemic and nonischemic CE was clearly different by 2 weeks after the operation. No trilaminar signal pattern was evident in the high resolution T2-weighted (T2W) imaging of the ischemic CE from 2 weeks after the operation. In the 3- to 8-week postoperative specimens, focal areas of low signal intensity on high resolution T1-weighted (T1W) and T2W imaging corresponded to the areas of chondronecrosis found on histologic assessment. The regions of high signal intensity on T2W imaging corresponded to the areas of chondrocyte clusters with increased safranin-O staining. High resolution MRI can demonstrate changes in the CE associated with ischemic injury and may have a role in the assessment of the CE and its development after ischemic injury.     

MR imaging of bone marrow edema and joint effusion in patients with osteonecrosis of the femoral head: relationship to pain

OBJECTIVE: Our aim was to determine the occurrence of bone marrow edema and joint effusion and their relationship to pain in patients with osteonecrosis of the femoral head on the basis of MR imaging. MATERIALS AND METHODS: There were 71 patients with osteonecrosis of the femoral head based on characteristic radiographic and MR imaging findings. All patients had surgical confirmation of the disease. Both hips were affected with osteonecrosis in 39 patients, whereas only one hip was involved in 31 patients. The last patient underwent an arthroplasty of one hip during the study and had only one hip imaged. We evaluated a total of 110 hips in this study, of which 98 were painful. We staged osteonecrosis of the femoral head, using the classification of Steinberg et al. The 31 unaffected hips served as controls. Bone marrow edema and joint fluid were evaluated on MR images. Bone marrow edema was defined as an ill-defined area of low signal intensity on T1-weighted images with corresponding high signal intensity on T2-weighted or inversion recovery images localizing to the femoral head, neck, and intertrochanteric region. The amount of joint fluid was graded from 0 to 3. RESULTS: The peak of bone marrow edema occurred in stage III disease (72%); its odds ratio was seven times greater than that for stage I osteonecrotic hips. Effusions of a grade greater than or equal to 2 were seen most often in stage III disease (92%), compared with 10% in the control hips. With an effusion, bone marrow edema was 12.6 times greater when the hip was painful than when it was not. CONCLUSION: Both bone marrow edema and joint effusions existed with a peak occurrence in stage III disease. Bone marrow edema seems to have a stronger association with pain than does joint effusion in osteonecrosis of the femoral head.     

Preoperative management of hip osteochondritis: comparison of MRI and arthrography with abduction views]

PURPOSE: Comparison between conventional arthrography and MRI in the preoperative work up of Legg-Calvé-Perthes disease. MATERIAL: ans methods. We studied 17 children (18 hips) who had arthrography and MRI (open-magnet configuration) the same day. Coronal and sagittal T1 weighted were realised with the hip in neutral position. Additional coronal T1 weighted with abduction of the hip were obtained. Two readers analysed individually MRI and arthrographic findings: shape of femoral head, index of Heyman (antero-external covering), came effect, recentering of femoral head and quality of examimation. RESULTS: No statistical difference between MRI and arthrography could be noted-exception made for the index of Heyman. CONCLUSION: MRI can replace arthrography in Legg-Calvé-Perthes disease.     

Longitudinal evaluation of cartilage repair tissue after microfracture using T2-mapping: a case report with arthroscopic and MRI correlation

A man sustained a left knee injury which led to full-thickness chondral defects of the trochlear groove and lateral femoral condyle. Both areas were treated with microfractures and evaluated at 5 months and 2 years with standard MRI scans, T2 relaxation maps, and arthroscopy. At 5-months post-microfracture repair, the patient complained of recurrent anterior knee pain. While standard MRI imaging was inconclusive with regards to a potential recurrent defect at the trochlear groove microfracture area, T2 relaxation maps established the integrity of the surface layer which was confirmed by arthroscopic evaluation. At 2 years, imaging studies revealed repair tissue loss with low T2 values at the trochlear repair site. The failure of the trochlear site and the integrity of the lateral femoral condyle repair sites were confirmed by arthroscopy. This case report is the first one to provide a correlation of T2 mapping MRI findings with arthroscopic confirmation in the context of microfracture repairs. The study provides evidence for the clinical utility of T2 relaxation maps for the postoperative assessment of microfractures and raises the potential for T2 mapping MRI as a tool to evaluate these repair procedures.     

Pigmented villonodular synovitis of the hip: review of radiographic features in 58 patients

Clinical and radiographic findings were retrospectively reviewed in a multicentric survey of 58 patients with histologically proven pigmented villonodular synovitis (PVNS) of the hip. The most common clinical features were mechanical pain (47 cases) and limitation of joint motion (47 cases). On plain films, a classic form with large and multiple lucencies was found in 36 cases, followed by an osteoarthritis-like form (9 cases), an arthritis-like form (8 cases), normal radiographic appearance (3 cases), osteonecrosis of the femoral head (one case) and joint destruction with acetabular protrusion (one case). Bilateral involvement of the hips was probable in two patients. In contrast to the knee, the hip showed a high prevalence of bony lesions and joint space narrowing. Although an uncommon disease, PVNS of the hip has to be considered when arthritis is associated with uncharacteristic clinical or radiographic findings.     

Magnetic resonance imaging of para-acetabular insufficiency fractures in patients with malignancy

AIM: To describe the characteristic magnetic resonance imaging (MRI) findings of para-acetabular insufficiency fractures in patients with malignancy, and compare the MRI appearance of these fractures with that of metastatic bone disease. MATERIALS AND METHODS: MRI examinations were reviewed in 16 patients with a known malignant tumour and severe hip pain that raised the possibility of local recurrence or metastatic disease. Six patients had received pelvic irradiation, and three patients were receiving steroid medication. RESULTS: The total number of fractures detected was 21: a solitary fracture was present in 11 patients and five patients had bilateral para-acetabular fractures. Two patients had associated sacral insufficiency fractures, and one of them had stress fractures involving both acetabular columns. Conventional radiography allowed the diagnosis of 14 (67%) fractures; six (28%) radiographic examinations were negative; and one (5%) examination was equivocal for fracture. Available scintigraphic and computed tomography (CT) studies revealed typical findings of fracture. Using MRI, insufficiency fractures appeared as linear regions of low signal intensity on T1- and T2-weighted images. Marked marrow oedema was evident in all cases. Fractures characteristically were parallel to the superior acetabulum in a curvilinear fashion in 18 (86%) instances, and were oblique in three (14%) instances. The fractures demonstrated considerable enhancement after intravenous gadolinium administration. No associated soft tissue masses were documented. CONCLUSION: Para-acetabular insufficiency fractures are a cause of hip pain, which may mimic skeletal metastasis in the patient with malignancy and pelvic irradiation. Recognition of the characteristic MRI findings of these fractures can preclude misdiagnosis and unnecessary bone biopsy.     

The validity of radiographic assessment of childhood transient synovitis of the hip

The diagnostic significance of some radiographic signs (abnormal hip 'joint space' and periarticular fat layers) as indicators of hip joint effusion or hip complaints without effusion was studied with ultrasonography and radiography in 47 children (58 examinations), of whom 40 had acute unilateral transient synovitis. It was found that 'joint depth' was not influenced by presence of intra-articular fluid collections; blurring and/or displacement of the periarticular fat pads medial and lateral to the hip joint occurred more frequently when joint effusion was present than in symptom-free hips or in painful hips without effusion. The radiographic signs provided, however, too low diagnostic accuracy to be of practical value. It is suggested that ultrasonography of the hip joint is a valuable means in obtaining a better definition of the diagnosis transient synovitis.     

The skeleton in congenital,generalized lipodystrophy: evaluation using whole-body radiographic surveys,magnetic resonance imaging and technetium-99m bone scintigraphy

Congenital generalized lipodystrophy (CGL) is a rare genetic disease characterized by the absence of body fat from birth. Focal bone lesions have also been reported, but their pathophysiology is poorly understood. To characterize skeletal abnormalities further in 3 patients with CGL, we employed whole-body radiographic skeletal surveys, magnetic resonance imaging (MRI, including gadolinium enhancement), and triple phase technetium-99m methylene diphosphonate bone scintigraphy. Radiographs showed numerous focal lesions within the long bones, as described in other reports. MRI showed that the entire marrow space of the long bones was abnormal and was characterized, at least in part, by the absence of marrow fat. Prolonged T1 and T2 times and marked gadolinium enhancement were observed in radiographically normal-appearing long bone. Radiographically lytic lesions occasionally demonstrated fluid-fluid levels on MRI and enhanced peripherally after gadolinium infusion. Bone scintigraphy findings such as periarticular hyperemia were relative subtle. We conclude that the appendicular skeleton of patients with CGL is diffusely abnormal and is predisposed to focal osteolysis and cyst formation.Supported in part by grants from the National Institutes of Health (M01-RR-00633)