Subchondral insufficiency fracture of the femoral head in a patient with alkaptonuria

We report a patient with alkaptonuria accompanied by bilateral rapidly destructive arthrosis of the hip. The destruction of the left hip joint with its severe functional impairment necessitated total hip arthroplasty (THA). The outcome was satisfactory. Both magnetic resonance imaging (MRI) and pathologic findings were compatible with a subchondral insufficiency fracture. A year and half later, during a follow-up visit, the patient complained of right coxalgia. Radiography showed that the right femoral head had already disappeared, requiring THA of the right hip. Although there have been a few reports of rapid destructive hip osteoarthritis associated with ochronotic arthropathy, the pathogenesis of the destructive change is not clear. Subchondral insufficiency fracture was diagnosed on MR imaging and pathologically confirmed in our patient with alkaptonuria, suggesting that subchondral insufficiency fracture is one of the causes of ochronotic hip destruction.     

Legg-Calvé-Perthes disease: MR imaging evaluation during manual positioning of the hip--comparison with conventional arthrography.

PURPOSE: To evaluate the use of magnetic resonance (MR) imaging during manual positioning of the hip, or multipositional MR imaging, in an open-magnet configuration to study femoral head containment, articular congruency, and femoral head deformity in Legg-Calvé-Perthes disease. MATERIALS AND METHODS: In 12 children with advanced Legg-Calvé-Perthes disease, multipositional MR imaging and conventional arthrography were compared in the assessment of containment, femoroacetabular congruency, and femoral head deformity. Images of the hips in several positions were compared subjectively and objectively. RESULTS: MR imging correlated well with arthrography for overall subjective assessment of severity of disease (r = 0.71, P = .01), with good interobserver agreement (kappa = 0.65, P < .001). MR images demonstrated all cases of hinge abduction shown arthrographically. However, MR imaging failed to depict one case of femoral head flattening. MR imaging correlated well with arthrography in the objective evaluation of joint fluid and lateral subluxation (r = 0.80, P < .01). MR imaging correlated poorly with arthrography in the measurement of sphericity of the femoral head. CONCLUSION: Multipositional MR imaging with an open-magnet configuration was comparable to arthrography for demonstration of femoral head containment and congruency of the articular surfaces of the hip. In the evaluation of deformity, it performed less well.     

Ischemic necrosis of the entire femoral head and rapidly destructive hip disease: potential causative relationship

 Objective. Rapidly destructive hip disease (RDHD) is an uncommon disorder of the hip that has been considered a disease of unknown cause and distinct from ischemic necrosis of the femoral head. The objective of this study was to investigate ischemic necrosis of the femoral head as one potential cause of RDHD. Design and patients. In 600 patients who underwent MR imaging of the hip, 20 cases of ischemic necrosis involving the entire femoral head in 18 patients (3%) were retrospectively studied with routine radiography and MR imaging. All patients had surgically confirmed ischemic necrosis of the femoral head. Results and conclusions. All patients showed rapid destruction of the femoral head on routine radiography and MR imaging as compared with the gradual onset of clinical symptoms. Plain radiographs showed several bone fragments at the inferomedial aspect of the femoral head (75%), acetabular erosions (55%), eccentric depression at the lateral articular surface of the femoral head conforming to the adjacent acetabulum (35%), and mild osteoarthritis (15%). Bone sclerosis was often present at sites of impaction between the femoral head and the acetabulum. MR imaging showed marked distention of the joint capsule in all cases. In 14 of 20 cases, the contents of the joint space showed predominantly low or intermediate signal intensity on T1- and T2-weighted images. Ischemic necrosis involving the entire femoral head may represent one of the causes of RDHD.     

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.     

MR imaging of iliopsoas bursitis and concurrent avascular necrosis of the femoral head

The magnetic resonance (MR) features of iliopsoas bursitis secondary to an inflammatory arthropathy of the hip are described in a patient with concurrent avascular necrosis of the femoral heads. The MR findings of avascular necrosis were demonstrated on one side where radiography, bone scan, and CT were negative.     

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.     

Magnetic resonance in the study of aseptic necrosis of the femur head

Avascular necrosis (AVN) of the femoral head is a common clinical problem due to the frequent use of corticosteroids and to the high incidence of hip fractures from osteoporosis and traumas. In order to demonstrate MR diagnostic capabilities, 31 patients (62 hips) were studied with MR imaging, CT, and conventional radiology. The patients had already been diagnosed as having AVN of the femoral head, or the condition was clinically suspected. MR staging of the disease was compared with CT staging and with plain radiographs. The authors suggest new MR staging method and adapt the radiographic classification developed by Ficat, Arlet, and Lecestre. The results of this comparative study demonstrate MR imaging to be most appropriate in the patients with equivocal/negative radiological/CT findings. On the contrary, MR imaging is unnecessary when AVN has already been diagnosed by means of other imaging modalities, because in these advanced cases MR diagnostic contribution either equals or is inferior to that of CT and conventional radiology.     

Screening for avascular necrosis of the hip with rapid MRI: preliminary experience

PURPOSE: The purpose of this work was to compare rapidly acquired MR images with routinely employed SE and turbo SE (TSE) images in screening for hip avascular necrosis (AVN). METHOD: Twelve patients with findings suspicious for radiographically occult AVN of one or both hips were studied with our routine screening protocol (imaging time >7 min) and similarly weighted, rapidly acquired MR sequences (imaging time <1 min). RESULTS: The rapidly acquired MR images were judged to be similar to the routine protocol in demonstrating marrow edema, irregular lines within the femoral head characteristic of AVN, and osteoarthritis. CONCLUSION: The rapidly acquired MR sequences that we studied reliably revealed the presence or absence of AVN, marrow edema, and osteoarthritis of the hip in our sample population when compared with SE and TSE sequences that we routinely perform. Further investigation of rapidly acquired MR sequences is warranted, as imaging time may be dramatically reduced and patient throughput increased.     

Hip pain in three children accompanied by transient abnormal findings on MR images

In a study of three children experiencing hip pain, low-signal-intensity patterns in the femoral head on T1-weighted magnetic resonance (MR) images eventually resolved, reverting to the normal signal patterns. These findings occurred in conjunction with documented clinical improvement of the patients' condition. T2-weighted images revealed isointense signals initially at the abnormal sites. Isointense signals prevailed on follow-up T2-weighted images. These MR imaging findings are likely due to transient bone marrow edema. These findings support the apparent sensitivity of MR imaging in the evaluation of marrow-based pathologic processes. Some pediatric patients with hip pain may have signs of transient bone marrow edema, rather than avascular necrosis, on MR images. Conservative management should be considered in such cases.     

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.     

Correlation between bone marrow edema and collapse of the femoral head in steroid-induced osteonecrosis

OBJECTIVE: The purpose of this study was to clarify whether bone marrow edema is detectable on initial MR imaging of steroid-induced osteonecrosis of the femoral head. SUBJECTS AND METHODS: Forty-eight hips with osteonecrosis were examined consecutively with MR imaging and radiography. In a previously reported screening program, osteonecrosis was diagnosed on MR imaging when subchondral bands of abnormal signals were present. In the screening program, the MR images of 200 hips of 100 patients receiving high-dose steroid therapy were examined prospectively. Subchondral bands were detected in 48 hips at a mean of 14 weeks after the initiation of steroid therapy. RESULTS: On follow-up MR imaging of 47 hips (one hip excluded) bone marrow edema was initially observed in 13 hips after the onset of hip pain. MR imaging of the remaining 34 hips did not reveal bone marrow edema and the patients were all asymptomatic. MR imaging of 31 of the 34 hips continued to show subchondral bands and MR imaging of the other three hips indicated that the subchondral bands had disappeared. When bone marrow edema was detectable, abnormal findings on radiography were slight but 11 (85%) of the 13 hips progressed to advanced osteonecrosis. Bone marrow edema was highly correlated with the subsequent collapse of the femoral head (p<0.0001). CONCLUSION: Bone marrow edema was not present on initial MR imaging of osteonecrosis. Bone marrow edema should be considered a marker for potential progression to advanced osteonecrosis, and careful examinations for osteonecrosis are necessary when bone marrow edema is seen.     

Bone marrow edema of the femoral head and transient osteoporosis of the hip

The current article of this issue aims at defining the generic term of bone marrow edema of the femoral head as seen at MR imaging. It must be kept in mind that this syndrome should be regarded, not as a specific diagnosis, but rather as a sign of an ongoing abnormal process that involves the femoral head and/or the hip joint. We aim at emphasizing the role of the radiologists in making a specific diagnosis, starting from a non-specific finding on T1-weighted images and by focusing on ancillary findings on T2-weighted SE or fat-saturated proton-density weighted MR images.     

Distinct focal lesions of the femoral head: imaging features suggesting an atypical and minimal form of bone necrosis

OBJECTIVE: To document the imaging findings observed in patients with an unusual pattern of abnormality of the femoral head, most likely representing osteonecrosis. DESIGN AND PATIENTS: The imaging findings in 11 patients (10 men, 1 woman; age range 32-55 years) with a distinct lesion of the femoral head were reviewed with particular attention to the morphologic appearance, location, and extent of the lesion(s) in the proximal femur. RESULTS: The 16 lesions identified in these patients extended to the subchondral area. Articular collapse was not evident in any hip. Radiography and CT showed areas of mixed bone sclerosis and osteolysis surrounded by sclerotic margins. On MR imaging, the signal intensity characteristics of the osseous lesion(s) were most commonly similar to those of fluid. Histopathologic findings, available in two hips, were typical of osteonecrosis. There was evidence of correlation of the site of the lesion with the known general distribution and anastomoses of arteries supplying the femoral head. CONCLUSION: A distinct, focal lesion of the femoral head is believed to represent an atypical form of bone necrosis. Its restriction to a small portion of the femoral head may relate to localized vascular anatomy. Recognition of the quite characteristic imaging findings can prevent misdiagnosis and may have implications for the prediction of the natural course of the disease.     

Bipositional MR imaging vs arthrography for the evaluation of femoral head sphericity and containment in Legg-Calvé-Perthes disease

Eleven hips of 10 patients with Legg-Calvé-Perthes disease (LCPD) were examined by arthrography and magnetic resonance (MR) imaging. Arthrogram and MR images were obtained with the hips in neutral position and in 20 degrees flexion-abduction and internal rotation. Modified arthrographic index (AI) was used for the evaluation of sphericity and acetabulum head index (AHI) was used for the assessment of containment. According to AI, there is no significant difference between the arthrograms and coronal MR imaging, but the difference between the coronal and sagittal MR imaging was significant. There was no statistical difference between the arthrograms and MR measurements in terms of AHI. Anterior flattening of the femoral head and the effect of hip flexion in the containment at the sagittal plane could be demonstrated clearly in sagittal MR imaging. Even if there was significant flattening in coronal plane, the sphericity of the head was preserved in the sagittal plane. Bipositional MR imaging is comparable to arthrography for the demonstration of sphericity and containment of the femoral head in both coronal and sagittal planes in LCPD.     

Septic arthritis versus transient synovitis at MR imaging: preliminary assessment with signal intensity alterations in bone marrow

PURPOSE: To find any differential magnetic resonance (MR) imaging findings between septic arthritis and transient synovitis in pediatric patients. MATERIALS AND METHODS: The MR imaging findings in nine pediatric patients with septic arthritis and 14 with transient synovitis were retrospectively studied. The diagnoses were made by means of joint aspiration with bacteriologic study, arthrotomy, and clinical evaluation. MR imaging findings were analyzed with emphasis on the grade of joint effusion and alterations in signal intensity in the soft tissue and bone marrow of the affected hip joint. RESULTS: Signal intensity alterations in bone marrow (i.e., low signal intensity on fat-suppressed gadolinium-enhanced T1-weighted spin-echo images and high signal intensity on fat-suppressed T2-weighted fast spin-echo images) were seen in eight of nine patients with septic arthritis. These signal intensity alterations consisted of mild juxtaarticular changes in six patients without osteomyelitis and extensive changes in the femoral head and neck in two patients with coexistent osteomyelitis. Signal intensity alterations in bone marrow were not seen in the 14 patients with transient synovitis. CONCLUSION: Signal intensity alterations in the bone marrow of the affected hip joint are useful in the differentiation of septic arthritis from transient synovitis.     

Low field magnetic resonance imaging of femoral neck fractures

Fourteen patients with cervical hip fractures were treated with internal fixation using titanium screws. The femoral head vitality was evaluated with 99Tcm-MDP scintigraphy and scintimetry within 2 weeks postoperatively and by serial low field magnetic resonance imaging (MR). Two patients with reduced radionuclide uptake (femoral head ratio less than 1.0) developed radiographic signs of femoral head necrosis. MR disclosed the definite area of the necrosis at 2 and 12 months after fracture, respectively. In three of the patients with a high scintimetric uptake (femoral head ratio greater than or equal to 1.0), MR revealed a focal decrease of the signal intensity in the femoral head or neck at 2, 3 and 7 months after fracture, respectively. The radiographs in one of these patients were normal at 7 months after fracture. The second one showed signs of necrosis at 16 months and the last one developed delayed/non-union. With a non-ferromagnetic osteosynthesis the healing course after femoral neck fracture can be studied with low field MR equipment without disturbing artifacts. The time period between ischaemia and definite abnormalities on MR may embrace several months.     

Width of the articular cartilage of the hip: quantification by using fat-suppression spin-echo MR imaging in cadavers.

OBJECTIVE. Use of MR imaging to measure the width of the articular cartilage has not been thoroughly investigated. The value of a selective fat-suppression spin-echo sequence in the quantitative assessment of articular cartilage of the hip was studied in cadavers. MATERIALS AND METHODS. Sagittal and coronal images were acquired in 10 cadaveric hips (age range at time of death, 62-81 years). On the coronal and sagittal MR images that were closest to the center of the femoral head, marks were placed every 30 degrees, with the midpoint of the femoral head used as a reference. Cartilage thickness was measured in 123 resulting locations. Sixty-three positions included both femoral and acetabular cartilages, and 60 positions included femoral cartilage without an acetabular counterpart. The findings were compared with corresponding anatomic sections. RESULTS. For the 60 locations containing only femoral cartilage, significant correlation between MR and anatomic sections was found (Pearson correlation coefficient = .34, p = .0089). Of the 63 locations containing both femoral and acetabular cartilages, the two cartilage layers could be differentiated on the MR images in 50 locations. In these 50, the MR and anatomic measurements of the femoral cartilage correlated significant (r = .58, p less than or equal to .0001). Measurements of the acetabular cartilage in these 50 locations yielded no significant correlation (r = .25, p = .08). When the entire cartilage (femoral plus acetabular) was measured in all 63 locations, the correlation between MR and anatomic measurements was .29 (p = .02). The correlation coefficients obtained in this investigation indicate considerable scattering of the data. CONCLUSION. Our results show that measurements of articular cartilage thickness of the hip on fat-suppression spin-echo MR images are not sufficiently accurate to be of clinical value.     

人工关节置换治疗晚期股骨头缺血性坏死合并严重股骨颈前倾角畸形

目的 探讨晚期股骨头缺血性坏死合并严重股骨颈前倾角畸形患者采用普通假体髋关节置换的手术方法及临床疗效.方法 本组男9例,女6例;年龄30～42岁,平均37岁.前倾角40°～50°,术前Harris评分(59±8)分,术中通过将股骨假体缩小前倾角20°～30°,同时将髋臼杯前倾角增大10°～15°,使其基本恢复正常对合关系,防止关节前脱位.术后定期影像学检查和临床疗效Harris髋评分.结果 术后15例患者均获得随访2.5～3.7年(平均2.9年),关节假体稳定性良好,关节活动度基本正常.术后2年Harris评分为(88±6)分,与术前相比,疗效显著(P<0.01).结论 晚期股骨头缺血性坏死合并严重股骨颈前倾角畸形患者手术中通过对普通的股骨假体及髋臼杯安放的角度的联合调整,使关节置换术后人工假体与髋臼的对合基本恢复正常,疗效显著,同时避免了使用小柄股骨假体、转子下截骨或使用特殊前倾角股骨假体等治疗方法.     

Early osteonecrosis of the femoral head: detection in high-risk patients with MR imaging

To determine whether magnetic resonance (MR) imaging can demonstrate the early stages of osteonecrosis that are not detectable radiographically, the authors compared radiologic findings with histologic results in seven patients at high risk for osteonecrosis of the femoral head. Radiography and MR imaging were performed, and proximal femoral intramedullary pressures were measured in all patients, even if results from imaging studies were normal. If the pressures were elevated, core decompression with biopsy was performed. Seven patients had elevated pressures in 11 hips. Of 11 hips from which biopsy specimens were taken, all had histologic evidence of osteonecrosis. However, in only five were the MR imaging findings consistent with osteonecrosis. In the remaining six hips with osteonecrosis, MR imaging findings were normal. Sensitivity of MR imaging in detection of osteonecrosis was 46%. The authors conclude that normal MR imaging results in high-risk patients do not rule out the presence of osteonecrosis.     

Legg-Calvé-Perthes disease: imaging with MR

Magnetic resonance (MR) imaging studies were obtained to evaluate the shape of the cartilaginous femoral head and the adequacy of femoral acetabular containment in 35 children with Legg-Calvé-Perthes disease (LCPD). MR results for 24 of the 35 children were compared with results at arthrography. The shape of the cartilaginous femoral head was well identified with MR imaging, but, with arthrography, less information could be obtained about the medial and lateral aspects of the cartilaginous capital epiphyses in nine and three cases, respectively. Thirteen children underwent surgery; remodeling and regained femoroacetabular congruity of the articular surfaces following derotation varus osteotomy was identified in seven of 10 who underwent repeat MR imaging. In addition, MR images and conventional radiographs of the hips were compared. The radiographically identifiable distribution of the bone necrosis of the capital epiphysis correlated well with that demonstrated on MR images. MR imaging is a valuable non-invasive procedure with which to obtain information about the status and treatment of the cartilaginous femoral head in children with LCPD.