股骨头坏死表面积测量及在股骨头塌陷预测中的应用

目的探讨采用磁共振扫描(magneticresonanceimaging,MRI)的图像,计算股骨头坏死(osteonecrosisofthefemoralhead,ONFH)表面积及坏死面积占整个股骨头表面积的百分比(简称坏死表面积比),检验其准确性,并应用于临床预测股骨头塌陷。方法2001年6月~2003年6月,对8例13髋拟行关节置换的ONFH患者术前作标准的MRI扫描,依T1连续图像计算,得出坏死表面积及坏死表面积比。将手术标本锯成与MRI扫描相同的层厚和层数,应用坐标纸粘贴,图像分析仪测出数据,并作统计学分析。另对16例25髋、期非手术治疗的ONFH患者,用MRI扫描图像法测定其股骨头坏死表面积及坏死表面积比,临床随访至股骨头出现塌陷,未塌陷者至少随访24个月,比较两者差异。结果MRI图像法与标本测量的数据差异无统计学意义(P>0.05)。随访的16例25髋中,17髋发生股骨头塌陷,坏死表面积为31.06±8.10cm2(95%CI26.58~35.55),坏死表面积比为58.91%±15.11%(95%CI51.14~66.68),未塌陷的8髋坏死表面积为14.16±9.32cm2(95%CI6.37~21.95),坏死表面积比为29.48%±19.76%(95%CI12.97~45.99)。未塌陷组中仅4髋坏死表面积比>33%,塌陷组均>33%。结论MRI图像法能较准确计算股骨头坏死表面积及坏死表面积比,可用于预测股骨头塌陷,坏死表面积比>33%为股骨头塌陷的临界值。此计算法仍较复杂,宜进一步简化,以利临床应用。     

激素性与酒精性股骨头坏死患者骨标本坏死区域病理与显微结构特点分析北大核心CSCD

目的观察激素性和酒精性股骨头坏死(osteonecrosis of the femoral head,ONFH)患者骨标本坏死区域的病理和显微结构特点。方法收集2015年8月—2016年4月因ONFH行人工全髋关节置换术的股骨头标本30个,其中男22例,女8例;酒精性15例,激素性15例;两组国际骨循环协会(ARCO)分期构成比较差异无统计学意义(Z=2.143,P=0.143)。取激素性与酒精性ONFH患者骨标本不同区域(坏死区、硬化区、正常区)骨组织,行大体观察、HE染色并计算空骨陷窝率。将完整股骨头标本行Micro-CT扫描,并进行骨微结构定量分析以下参数:骨小梁相对体积(bone volume to total volume,BV/TV)、骨表面积与骨骼体积比(bone surface area to bone volume ratio,BS/BV)、骨矿密度(bone mineral density,BMD)、骨矿容量(bone mineral content,BMC)、结构模型指数(structure model index,SMI)、骨小梁数目(trabecular plate number,Tb.N)、骨小梁厚度(trabecular plate thickness,Tb.Th)、骨小梁间隙(trabecular spacing,Tb.Sp)。结果大体观察示激素性和酒精性ONFH均有骨小梁连续性中断,骨小梁吸收区域有囊变被肉芽组织取代,激素性ONFH肉芽组织内有血管新生的痕迹,酒精性ONFH肉芽组织内血管新生痕迹不明显。HE染色示激素性和酒精性ONFH坏死区均有骨质结构紊乱、骨髓坏死、骨陷窝空虚,其中激素性ONFH骨小梁结构和连续性破坏更严重,酒精性ONFH骨小梁更粗,连续性较激素性ONFH好。激素性ONFH坏死区的空骨陷窝率明显高于酒精性ONFH(P<0.05),但两种ONFH硬化区和正常区空骨陷窝率比较差异无统计学意义(P>0.05)。激素性与酒精性ONFH坏死区与硬化区之间区域在Micro-CT图像中均是低密度区,但前者形态不规则,对应部位大体标本可见富含血运的肉芽组织形成,后者对应部位大体标本见无血运的纤维肉芽组织形成。骨微结构定量分析显示,激素性ONFH坏死区和硬化区BV/TV、BMD、BMC、Tb.N、Tb.Th明显低于酒精性ONFH,BS/BV、SMI、Tb.Sp显著高于酒精性ONFH,差异均有统计学意义(P<0.01);两种ONFH正常区上述各指标比较差异均无统计学意义(P>0.05)。结论激素性和酒精性ONFH标本坏死区的骨小梁连续性均破坏。但两种ONFH有不同的坏死表现形式,激素性ONFH以多发灶性溶骨性骨质破坏为特点,酒精性ONFH是以凝固性骨质坏死为特点。     

激素性与酒精性股骨头坏死患者骨标本坏死区域病理与显微结构特点分析

目的观察激素性和酒精性股骨头坏死(osteonecrosis of the femoral head,ONFH)患者骨标本坏死区域的病理和显微结构特点。方法收集2015年8月—2016年4月因ONFH行人工全髋关节置换术的股骨头标本30个,其中男22例,女8例;酒精性15例,激素性15例;两组国际骨循环协会(ARCO)分期构成比较差异无统计学意义(Z=2.143,P=0.143)。取激素性与酒精性ONFH患者骨标本不同区域(坏死区、硬化区、正常区)骨组织,行大体观察、HE染色并计算空骨陷窝率。将完整股骨头标本行Micro-CT扫描,并进行骨微结构定量分析以下参数:骨小梁相对体积(bone volume to total volume,BV/TV)、骨表面积与骨骼体积比(bone surface area to bone volume ratio,BS/BV)、骨矿密度(bone mineral density,BMD)、骨矿容量(bone mineral content,BMC)、结构模型指数(structure model index,SMI)、骨小梁数目(trabecular plate number,Tb.N)、骨小梁厚度(trabecular plate thickness,Tb.Th)、骨小梁间隙(trabecular spacing,Tb.Sp)。结果大体观察示激素性和酒精性ONFH均有骨小梁连续性中断,骨小梁吸收区域有囊变被肉芽组织取代,激素性ONFH肉芽组织内有血管新生的痕迹,酒精性ONFH肉芽组织内血管新生痕迹不明显。HE染色示激素性和酒精性ONFH坏死区均有骨质结构紊乱、骨髓坏死、骨陷窝空虚,其中激素性ONFH骨小梁结构和连续性破坏更严重,酒精性ONFH骨小梁更粗,连续性较激素性ONFH好。激素性ONFH坏死区的空骨陷窝率明显高于酒精性ONFH(P0.05),但两种ONFH硬化区和正常区空骨陷窝率比较差异无统计学意义(P0.05)。激素性与酒精性ONFH坏死区与硬化区之间区域在Micro-CT图像中均是低密度区,但前者形态不规则,对应部位大体标本可见富含血运的肉芽组织形成,后者对应部位大体标本见无血运的纤维肉芽组织形成。骨微结构定量分析显示,激素性ONFH坏死区和硬化区BV/TV、BMD、BMC、Tb.N、Tb.Th明显低于酒精性ONFH,BS/BV、SMI、Tb.Sp显著高于酒精性ONFH,差异均有统计学意义(P0.01);两种ONFH正常区上述各指标比较差异均无统计学意义(P0.05)。结论激素性和酒精性ONFH标本坏死区的骨小梁连续性均破坏。但两种ONFH有不同的坏死表现形式,激素性ONFH以多发灶性溶骨性骨质破坏为特点,酒精性ONFH是以凝固性骨质坏死为特点。     

激素性和酒精性股骨头坏死组织形态学的比较研究

目的对激素性和酒精性股骨头坏死(ONFH)进行组织形态学比较研究。方法将13个坏死的股骨头按程序制成普通病理切片,进行HE、改良Masson染色,在光学显微镜下对ONFH的组织形态学进行定量分析,实验数据采用单因素方差分析统计处理。结果激素性ONFH组骨小梁面积、空骨陷窝率、脂肪细胞长径、新生骨小梁面积均低于酒精性ONFH组(P<0.05),而软骨成骨指数高于酒精性ONFH组(P<0.05);两组骨陷窝面积和长径、同源软骨细胞数、有效血管和无效血管数无显著性差异(P>0.05),但激素性ONFH组有效血管和无效血管数在数值上均高于酒精性ONFH组。结论激素性和酒精性ONFH的坏死表现形式不同,修复的方式也不同。     

MRI和CT诊断早期股骨头坏死的价值

目的比较MRI和CT诊断早期股骨头坏死的价值。方法选择2015-01—2017-01间收治的110例早期股骨头坏死患者,均采用MRI和CT进行双侧股骨头扫描,并经手术及骨穿病理证实,比较分析2种不同影像学的诊断结果。结果 MRI的阳性检出率(95.98%)显著高于CT(89.08%),差异有统计学意义(P0.05)。结论与CT检查比较,MRI诊断股骨头坏死的敏感性和准确性更高,能较好呈现病灶的形态和病理,利于股骨头坏死的早期诊断,且安全性高。     

股骨头缺血性坏死MRI表现及其与预后的关系

目的 分析股骨头缺血性坏死（ONFH）磁共振成像（MRI）表现及其与预后的关系。方法 回顾性分析2019年1月至2022年1月临床确诊的153例ONFH患者的病例资料。入院后在髋关节MRI检查前对患者均进行X线检查,记录ONFH患者X线及MRI表现。在术后对患者进行随访,时间为12个月,记录患者预后情况。比较不同预后患者MRI影像征象,分析其与预后的关系。结果 本研究中对153例ONFH患者使用X线检查,共检出股骨头坏死70例,共计110个股骨头坏死,其中64个（58.18%）股骨头囊性改变,39个（35.45%）骨小梁增粗模糊,19个（17.27%）骨密度增加。MRI检查共诊断217个股骨头坏死,国际骨循环研究（ARCO）Ⅰ期69个（97.18%）股骨头坏死,Ⅱ期85个（96.59%）股骨头坏死,Ⅲ期44个（100%）股骨头坏死,Ⅳ期19个（100%）股骨头坏死,检出率为97.95%(217/222),MRI检查检出率高于X线检查（P<0.05）。预后良好组MRI图像显示股骨头光滑,T1及T2加权图像呈高信号,股骨头呈低信号;预后不良组MRI检查显示斑片状硬化,“线性”股骨头合...     

酒精性股骨头缺血性坏死与CYP450关系研究进展

目的 长期过量饮酒引起的股骨头缺血性坏死(osteoarthrosis of femoral head,ONFH)是一种严重威胁人类健康的疾病,多发于20 ～ 50岁的青壮年.随着人们生活方式的改变,酒精性股骨头坏死的临床病例日渐增多,酒精性股骨头坏死(alcohol-induced osteoarthrosis of femoral head,AIONFH)的发病机制尚不完全清楚,很多学者认为主要与一些基因有关,各国学者报道情况不一,各持己见;本文就国内外酒精性股骨头坏死与CYP450的关系作一综述.     

坏死面积比例在预测股骨头塌陷中的价值

目的探讨股骨头的坏死面积比例在预测股骨头塌陷中的价值。方法测量9例(15髋)股骨头坏死标本的坏死面积比例,同时根据MRI计算该9例患者的坏死面积比例,两者进行比较。对8例(16髋)行2次及以上MR检查的患者进行研究,比较第一、二次MRI上股骨头坏死面积比例的相关性。两次MR检查间隔平均18.9个月。根据27例(38髋)早期股骨头坏死患者的MRI表现,计算坏死面积比例及坏死指数,并进行随访。对发生坏死塌陷的股骨头的坏死面积比例和坏死指数进行计算。结果标本和MRI上的坏死面积比例为63.23%±10.16%和63.60%±7.78%,两者比较差异无统计学意义,表明通过MRI计算出的坏死面积比例与标本测量所得的坏死面积比例一致。第一、二次MRI上的坏死面积比例分别为52.37%±19.91%和51.70%±21.29%,两者比较差异无统计学意义,表明股骨头的坏死面积比例不随病程的延长而变化。在38髋早期坏死的股骨头中,有28髋塌陷,10髋未塌陷,塌陷与未塌陷患者的ARCO分期比较差异无统计学意义,表明缺血性坏死的股骨头是否塌陷与其分期无关。坏死面积比例与坏死指数的相对危险度为1.043和1.020,表明坏死面积比例更能准确预测缺血性坏死的股骨头是否塌陷。结论股骨头的坏死面积比例可以较准确地预测缺血性坏死的股骨头是否塌陷。     

股骨头坏死相关标志物研究进展

目前诊断股骨头坏死(ONFH)最有效方法为MRI检查,早期诊断率达到90％以上,但即使如此,也很难使之逆转.随着基因组学、蛋白质组学和代谢组学研究深入,MRI早期诊断前发现更早期相关标志物对预测和预防ONFH具有重要意义.该文就近年ONFH标志物研究热点及进展作一综述.     

基于超薄层切片与计算机辅助识别技术股骨头坏死病灶测量比对研究

目的 :将计算机半自动股骨头坏死识别及定量检测软件系统与基于超薄层切片的测量方法进行比对分析,确认软件测量法的精确性和实用性。方法:回顾性分析2012年6月至2013年12月收治的24例单侧晚期(ARCO分期为Ⅲ、Ⅳ期)股骨头缺血性坏死患者术前双髋X线片与MRI资料,男15例,女9例,平均年龄(65.1±8.8)岁(33~74岁)。在影像学系统界面和计算机辅助技术(CAD)区域识别种子点自适应寻找方法软件系统下,计算出患侧MRI上股骨头坏死组织区域的体积,与患侧全髋人工关节置换术后的基于超薄层切片的测量方法进行比对分析。结果:软件测量24髋坏死病灶的体积为(20.00±3.04)cm~3(18.72~21.29 cm~3),大体病理超薄层切片测得24髋股骨头坏死病灶的体积为(19.89±3.17)cm~3(18.55~21.23 cm3)。计算机软件与病理超薄层切片两种测量下,股骨头坏死病灶体积值的差异无统计学意义(t=-1.227,P=0.232)。结论:计算机半自动股骨头坏死识别软件系统可以较精确地测算MRI图像上股骨头坏死病灶的区域,与病理量化的测算范围符合,可以指导临床治疗。     

Measurement of lesion area and volume by three-dimensional spoiled gradient-echo MR imaging in osteonecrosis of the femoral head.

The purpose of this investigation is to evaluate the diagnostic ability of three-dimensional spoiled gradient-echo (3D SPGR) magnetic resonance (MR) imaging in cases of osteonecrosis of the femoral head (ONFH), and to determine the accuracy of 3D SPGR imaging in area and volume measurement of ONFH. T1-weighted spin-echo (SE) and 3D SPGR imaging were performed on 20 femoral heads obtained from patients with ONFH. After MR imaging, the femoral heads were cut parallel to the imaging plane and were evaluated histologically. Areas and volumes of necrotic lesions were measured with a computer program and the deviation between MR images and anatomical measurements was evaluated. A low signal intensity band on 3D SPGR MR images was observed in all femoral heads and corresponded histologically to repaired marrow with viable fibrous mesenchymal tissue. The area proximate to the low band area coincided with the necrotic region. Both area and volume measurements by T1-weighted SE and 3D SPGR images showed a strong correlation to histological measurements. The discrepancies between histological and imaging results were minimal in 3D SPGR imaging, especially at the anterior and posterior portions of the femoral head. Three-dimensional SPGR imaging provides more accurate measurements of the area and volume of a necrotic lesion than T1-weighted SE imaging.     

Multimodal imaging quantitation of the lesion size in osteonecrosis of the femoral head

Early diagnosis of osteonecrosis of the femoral head is important for initiating early treatment, which is associated with a more favorable outcome for patients. Confusion in evaluating the severity of the disease, and the clinical outcome after treatment partially is attributed to the use of various staging systems that are based on qualitative rather than quantitative criteria. At the authors' institution, 45 patients (77 hips) with osteonecrosis of the femoral head were evaluated using a multimodal imaging approach that included conventional radiography, bone scintigraphy, and magnetic resonance imaging. A computerized image analysis program that allowed quantification of the lesion size on radiographs and magnetic resonance images was used. Measurements of the extent of involvement on radiographs and selected serial magnetic resonance images were compared in 33 hips (42.9%) before collapse versus 44 hips (57.1%) after collapse. The size of the necrotic lesion varied significantly according to the specific stage of disease. Quantification of the lesion during the course of the disease provided a record of the progression of osteonecrosis, despite a spurious stability in staging. In general, conventional radiography closely approximated measurements of the lesion size obtained by magnetic resonance imaging. Bone scintigraphy and magnetic resonance imaging were well suited for detection of osteonecrosis at an early stage. Finally, precise quantification of the lesion size was an optimal preoperative means for evaluating the extent of involvement of the femoral head in the early and advanced stages of osteonecrosis.     

Evaluation of magnetic resonance imaging in the diagnosis of osteonecrosis of the femoral head. Accuracy compared with radiographs, core biopsy, and intraosseous pressure measurements

The accuracy of magnetic resonance imaging in the detection of osteonecrosis of the femoral head was compared with that of other diagnostic methods in current use: plain radiography, bone-marrow pressure determinations, intramedullary venography, and histological examination of core-biopsy bone specimens. In the first phase of the study, forty-eight patients (ninety-six hips) who were at high risk for avascular necrosis were studied. Abnormal patterns on magnetic resonance imaging, consistent with those seen in necrosis, were found in all hips that were suspected of having Ficat Stage-2 or 3 changes on the basis of radiographic evidence of the disease. Abnormal patterns on magnetic resonance imaging that were characteristic of avascular necrosis were also observed in 17 per cent of the hips that were suspected of having Ficat Stage-0 changes and in 64 per cent of those that showed Stage-1 changes, all with no radiographic changes. In the second phase of the study, twenty-three of the ninety-six hips that were suspected of having early-stage necrosis of the femoral head but showed slight or no radiographic changes were studied by repeat radiographs, Ficat functional evaluations of bone, core biopsies of the femoral head, and magnetic resonance imaging. Of the twenty-three hips, eighteen (78 per cent) had positive changes on magnetic resonance imaging; nineteen (83 per cent) had positive histological evidence of necrosis; and fourteen (61 per cent) had positive findings by bone-marrow pressure studies and intramedullary venography. Although false-negative and false-positive results were observed with magnetic resonance imaging, the over-all results of this study suggest that magnetic resonance imaging may be useful for the early diagnosis of avascular necrosis.     

Correlation of the findings of magnetic resonance imaging with those of bone biopsy in patients who have stage-I or II ischemic necrosis of the femoral head

A prospective study was undertaken to determine the diagnostic accuracy of magnetic resonance imaging in the evaluation of a symptomatic hip for which a diagnosis of early ischemic necrosis of the femoral head was suspected. Fifteen patients (sixteen symptomatic hips), for whom the findings of magnetic resonance imaging were consistent with a diagnosis of osteonecrosis of the femoral head, had a core decompression and a biopsy of the contents of the core. Preoperative magnetic-resonance imaging was useful for planning which segment of the femoral head should be biopsied. Plain radiographs and tomograms of the hips were also made. On the basis of the plain radiographs, ten hips were determined to have Stage-I findings and six hips, Stage-II ischemic necrosis, according to the system of Ficat and of Arlet and Ficat. Histological study revealed evidence of necrosis in all of the biopsy specimens of bone. We concluded that findings of magnetic resonance imaging that are characteristic of osteonecrosis correlate well with the results of biopsies of bone in patients who have an early stage of ischemic necrosis. Magnetic resonance imaging is a highly sensitive and specific method for both the diagnosis and the location of Stage-I and Stage-II osteonecrosis.     

Magnetic resonance imaging and histology of repair in femoral head osteonecrosis

Different repair processes affect the clinical course of nontraumatic avascular femoral head osteonecrosis, not just necrotic lesion size and location. Fourteen femoral heads were retrieved at total hip arthroplasty after core decompression treatment, or after conservative treatment was done on 13 male patients diagnosed with different stages of femoral head osteonecrosis. To determine repair types, features of coronal magnetic resonance images were correlated with light microscopy findings on corresponding coronal undecalcified sections and microradiographs of the retrieved femoral heads. In five femoral heads, repair of necrotic bone and marrow remained restricted to the reactive interface for as many as 63 months, producing the diagnostic osteosclerotic rim with adjacent hypervascularity (limited repair). Nine femoral heads showed extension of the repair process into the necrosis. In five femoral heads, predominant resorption of necrotic bone led to femoral head breakdown within 2 to 50 months (destructive repair). In four femoral heads, reparative bone formation had started from subchondral fractures and/or the reactive interface, definitely reducing the size of the necrotic area (reconstructive repair). In the latter, the disease progressed slowly or stopped for as many as 45 months, irrespective of treatments, but elimination of risk factors seemed beneficial. Although core decompression did not always reach the necrotic area and improve repair, it reduced accompanying bone marrow edema and could delay the disease progress. Osteonecrosis with limited repair can be identified on magnetic resonance images obtained at followup, but the similar signal changes of destructive and reconstructive repair cannot be distinguished on magnetic resonance images alone. The evidence of reconstructive repair in nontraumatic osteonecrosis, however, gives hope for treatments that can improve repair to a sufficient creeping substitution of the affected femoral head.     

Magnetic resonance imaging and histopathology in the femoral head

To correlate the magnetic resonance (MR) images with the histopathological findings in the femoral head, the histopathology of 24 femoral heads, 15 with osteonecrosis, five with osteoarthritis and four with other hip disorders were subjected to preoperative MR imaging which demonstrated low intensity areas due to long T1 relaxation time in the femoral head. The MR signal was low where fibrovascular tissue, disintegrated fibrovascular tissue, amorphous necrotic material, bone, or cartilagenous tissue occupied the medullary space. From this study, it seems possible to predict the histopathologic changes in the femoral head using MR images.     

Prediction of posttraumatic femoral head osteonecrosis by quantitative intraosseous aspirate and core biopsy analysis: a prospective study

Twenty-two patients with unreduced hip dislocation or fracture dislocation were prospectively evaluated. Intraosseous aspiration, marrow fluid analysis and core biopsy histological analysis was performed from the supero-lateral (test group) and central part (control group) of the femoral head. After appropriate surgical treatment and postoperative management, they were followed up for 2 years by clinical, radiological and magnetic resonance imaging evaluation. Eight patients eventually developed avascular necrosis (AVN) of the femoral head. The analysis of test samples revealed that 9 patients had an aspirate volume of < 1 cc ; marrow morphology of 11 hips showed necrotic cells; 12 patients had a core biopsy histology suggestive of dead osseous fragments and necrotic osteocytes. In contrast, all the control samples had an aspirate volume of > 1cc and showed viable cells on histology. Intra-operative assessment of marrow-aspirate volume (< 1cc), marrow morphology and core biopsy histology from the superolateral part of femur head can fairly predict the development of subsequent ONFH after trauma; the correlation is statistically significant (p < 0.05).     

Osteonecrosis of the femoral head after solid organ transplantation: a prospective study

BACKGROUND: The reported prevalence of osteonecrosis of the femoral head in patients who have undergone a solid organ transplant has ranged from 3% to 41%. The wide variation is due to the retrospective nature of most studies and the inability to capture data on asymptomatic patients. The primary goals of this study were to determine the true prevalence of osteonecrosis of the femoral head following solid organ transplantation, the time to the development of the osteonecrosis, and whether findings on magnetic resonance imaging precede the onset of symptoms. METHODS: Beginning in 1997, patients who had undergone a solid organ transplant were asked to participate in a prospective study in which they would be screened for osteonecrosis of the femoral head. Inclusion criteria included an age of greater than fourteen years, a first-time transplant, and magnetic resonance imaging performed within six months after the transplant. Exclusion criteria were pre-existing osteonecrosis of the femoral head in the hip included in the study, a history of inflammatory arthritis, previous hip surgery, any contraindication to magnetic resonance imaging, a prior organ transplant, prior systemic corticosteroid treatment, and mental health issues preventing adequate follow-up. Screening magnetic resonance imaging was performed every four months. Survivorship analysis was used to determine the prevalence of osteonecrosis of the femoral head. RESULTS: Fifty-two patients (103 hips) were enrolled in the study. Their ages ranged from twenty-four to sixty-five years (mean, forty-three years). Sixteen patients were dropped from the study, but the data collected on them before they were dropped were included in the analysis. Osteonecrosis of the femoral head was diagnosed in eight of the 103 hips. Survivorship analysis revealed that, at one year after the transplant, 89% +/- 7% of the hips and 80% +/- 13% of the patients were free of osteonecrosis of the femoral head; thus the prevalence of osteonecrosis one year after transplantation was 11% or 20%, respectively. The mean duration of follow-up of the remaining hips was 2.3 years. In two hips the osteonecrosis of the femoral head was seen on the initial screening magnetic resonance imaging, and in the other six it developed after the initial magnetic resonance imaging revealed negative findings. All cases of osteonecrosis of the femoral head developed within ten months after the transplant. Seven of the eight hips were asymptomatic at the time of diagnosis. There was a significant difference in the one-year osteonecrosis-free survival rate between the patients who were less than forty years old (78%) and those who were at least forty years old (97%) (p = 0.011). Diabetes, smoking, and rejection episodes were not risk factors for osteonecrosis of the femoral head. CONCLUSIONS: Our study of patients who had had a solid organ transplant revealed that the true prevalence of osteonecrosis of the femoral head in such patients is lower than that reported in most previous studies, osteonecrosis of the femoral head develops prior to the onset of symptoms, an age of less than forty years is a risk factor for osteonecrosis of the femoral head, and osteonecrosis of the femoral head develops within one year after transplantation. We recommend that magnetic resonance imaging be used to screen for osteonecrosis of the femoral head within one year after transplantation. The utility of additional magnetic resonance imaging after one year has not been established.