Transient osteoporosis of the hip. Magnetic resonance imaging

Magnetic resonance (MR) images of seven hips were reviewed in six patients with transient osteoporosis of the hip. The MR images of the affected joint showed increased joint fluid and diffuse signal abnormalities in the marrow of the femoral head, corresponding to a decreased signal intensity on T1-weighted images and an increased signal intensity on T2-weighted images. The MR images at the time of clinical improvement showed regression of the abnormalities. These MR abnormalities reflect the pathophysiology of this condition.     

8例髋关节暂时性骨质疏松症的临床诊断与治疗

目的探讨髋关节暂时性骨质疏松症（transient osteoporosis of the hip,TOH）的临床表现、诊断、鉴别诊断、治疗及预后。方法2003年8月至2009年8月治疗8例TOH患者,男2例,女6例;年龄22—43岁,平均34．9岁。患者均为单侧发病,左侧5例,右侧3例。患者的患髋均表现有不同程度的突发急性疼痛或渐进性疼痛,同时伴有显著的跛行。患髋内旋轻度受限是主要的体征。症状出现后3—6周,x线片可见股骨头均匀广泛的骨质疏松,MR表现为弥散且一致的等低T1、长T2异常信号,脂肪抑制序列呈高信号。嘱患者在疼痛可忍受的条件下半负重行走,避免出现骨折等并发症;口服二膦酸盐和钙剂;剧烈疼痛时,可口服非甾体类抗炎药物缓解疼痛。结果临床治疗3个月后疼痛明显减轻,10个月后疼痛完全缓解,复查MR示病变完全消失。结论TOH是一种少见的疾病,无原因出现的髋关节疼痛和跛行是主要症状,X线片和MR可分别看到暂时性的骨质疏松和骨髓水肿。此病具有自限性,保守治疗可获得良好的结果,明确诊断是治疗的关键。     

Fatty marrow conversion of the proximal femoral metaphysis in transient bone marrow edema syndrome

Introduction In the proximal femoral metaphysis, hematopoietic marrow is predominant during the adult stage of life. The conversion of hematopoietic marrow to fatty marrow in the proximal femoral metaphysis has been suggested as an etiologic factor of ischemia in the pathogenesis of femoral head osteonecrosis. To determine whether the chronology of fatty marrow conversion of the proximal femoral metaphysis is related to transient bone marrow edema syndrome of the hip, a case control study was conducted on 10 patients with the disease.Materials and methods There were 8 men and 2 women with a mean age of 33 years (range 19–45 years). The 10 patients were matched with 20 controls for gender and age (5-year range). T1-weighted MRI scans of their hips were reviewed. Marrow of the greater trochanter becomes fatty before puberty, and thus, the greater trochanter can be used as a built-in control. The signal intensity of the proximal femoral metaphysis was compared to that of the greater trochanter.Results In all patients, the signal intensity of the proximal femoral metaphysis was isointense (fatty marrow) relative to that of the greater trochanter. In control subjects, the signal intensity was isointense in 8 (40%) and hypointense (hematopoietic marrow) in 12 (60%) (p<0.05).Conclusion The current study shows that the proximal femoral metaphysis is predominantly fatty in transient bone marrow edema syndrome. The conversion of hematopoietic to fatty marrow is known to correlate with decreases in intramedullary blood flow. Thus, the current study suggests that an ischemia of the proximal femur secondary to fatty marrow conversion of the proximal femoral metaphysis might be a cause of transient bone marrow edema syndrome of the hip.     

儿童早期化脓性髋关节炎:3.0TMR影像特征分析

目的探讨儿童早期化脓性髋关节炎3．0TMR影像特征。方法收集我院2004年1月2008年4月间发病时间在两周之内确诊为早期化脓性髋关节炎21例，所有病例均经临床血细菌培养、关节液细菌培养和组织学病理检查证实，所有患者均行3．0TMR双侧髋关节轴位及冠状位平扫，分析3．0TMR早期化脓性髋关节骨髓、骨骺、软骨、周围软组织影像特征性改变。结果MR表现：①患髋骨髓、骨骺及软骨信号改变：化脓性髋关节炎中13例患者股骨头骨骺及干骺端内部信号不均，骨骺形态失常，呈斑片状长T1长T2信号，为骨质破坏的表现，累及骺板者表现为穿越骺板的T2WI条形高信号影，累及骨骺软骨者表现为骺软骨薄厚不均，信号异常，还可以累及相邻的髂骨、耻骨。②患髋关节周围软组织信号改变：19例化脓性髋关节炎患者髋周软组织T2W—SPAIR上高信号（水肿表现），多累及髂肌、臀肌、耻骨肌及股内外侧肌，其中1例化脓性关节炎患者仅表现为肌间隙条片状高信号。③髋关节积液：21例均出现患侧髋关节积液，其中2例同时出现健侧髋关节积液。结论3．0TMR检查有助于儿童早期化脓性髋关节炎诊断与鉴别诊断，儿童早期化脓性髋关节炎3．0TMRI影像特征为骨髓、骨骺及软骨信号的异常升高和患髋关节周围软组织水肿。     

Transient osteoporosis of the hip

We report four cases of transient hip osteoporosis studied between 1995 and 1997. All patients were men. The diagnosis was based on clinical symptoms, absence of abnormal laboratory tests, increased uptake in the femoral head and neck on Tc-99 bone scans and magnetic resonance imaging showing Oedema of the bone marrow. In three patients radiographs showed osteopenia of the head and neck of the involved femur, whereas no major radiographic changes were seen in the fourth patient. The clinical symptoms lasted 7 months and there was no recurrence after 8-24 months' follow-up.     

Transient Peripartum Osteoporosis of the Femoral Head in First and Third Pregnancy

The aim of this article was to present transient peripartum femoral head osteoporosis. This very rare condition occurred twice in our patient—a woman in her 30s. The cases described in the literature were mostly unilateral, with bilateral hip involvement noted much less frequently. In our patient, transient osteoporosis occurred in the third trimester of her first pregnancy in the right hip, her second pregnancy was uncomplicated, and in the third trimester of the patient's third pregnancy, osteoporotic changes were noted in the left hip joint. The patient breastfed her first and third babies only 3 wk each. She breastfed her second baby for 4 mo. The diagnostic workup was based on the clinical examination and radiographic/magnetic resonance imaging, which revealed bone marrow edema, and the dual-energy X-ray absorptiometry scans. The treatment consisted in core decompression of the femoral head (foragé), unloading of the hip using crutches as well as administration of calcitonin and calcium supplements. Complete recovery of the femoral heads was achieved. The follow-up time was 7 yr.     

Correlation of MRI images with histology in avascular necrosis in the hip. A preliminary study

The role of MRI in identifying the tissue level changes in the femoral head was investigated in five patients diagnosed as having avascular necrosis by radiology, scintigraphy, and MRI (0.35 Telsa). Radiographic scoring by the Ficat and Arlet system showed one hip with stage I, one stage II, two stage III, and one stage IV changes. The histologic features of core biopsy specimens obtained during decompression of the femoral heads were compared to the preoperative T1 and mixed T1/T2-weighted MR images. The cores varied with respect to their distance from the subchondral bone (7-23 mm) and length (19-45 mm). At the subchondral end of the core tract, low T1-weighted images corresponded to marrow fibrosis (5 cases) and in three of five cases to increased trabecular bone volume (TBV = 44-50%). Subjacent areas of diffusely decreased MR signal corresponded to marrow fibrosis and necrosis, with a relatively normal TBV (17-28%). The distal ends of the core tracts showed normal fatty marrow and a normal MR signal. The observations affirm that the MR signal intensity is largely reduced as a function of marrow degeneration and loss of fat content, but the signal is not predictive of particular histotypic morphologic patterns.     

Diagnosis of transitory osteoporosis of the hip and its imaging in magnetic resonance tomography

Magnetic resonance (MR) imaging may distinguish transient osteoporosis of the hip from more severe hip diseases. 12 patients with transient osteoporosis of the hip underwent MR imaging. The initial and follow-up studies included T1- and T2-weighted images in coronal, transverse or sagittal planes. There were revealed 3 stages: diffuse-, focal-, and residual stage. This syndrome is characterized by hip pain, limping, and osteoporosis of the femoral head with preservation of the joint space. The clinical symptoms and abnormalities on MR images disappeared completely within 6-10 months.     

Idiopathic transient osteoporosis of the hip

We have reviewed 11 patients with idiopathic transient osteoporosis of the hip; the six who were women all developed the condition during pregnancy. Both simultaneous and sequential bilateral involvement were seen, but biochemical studies were consistently normal and one synovial biopsy showed only non-specific inflammation. Radioisotope bone scans and CT scans were useful to aid diagnosis. Treatment by limiting weight-bearing relieved symptoms, and spontaneous resolution was paralleled by radiographic remineralisation, usually within a few months. One patient developed a stress fracture of the hip and other areas of transient osteoporosis. A hip involved by the condition should be protected from overloading until bone density has recovered.     

Magnetic resonance imaging of the ischemic femoral head in pigs. Dependency of signal intensities and relaxation times on elapsed time

The magnetic resonance (MR) signal behavior of freshly excised pig femoral heads undergoing ischemic necrosis in vitro was evaluated. Ten femoral heads removed from skeletally immature pigs were stored at 37 degrees in a sealed, sterile container during the observation period. Imaging was initially performed 40 minutes after excision (base-line) and repeated at six, 12, 24, 48, and 72 hours. Changes in MR signal intensity were measured, and the T1 and T2 relaxation times were calculated for selected epiphyseal and metaphyseal areas. Signal intensities decreased during the first 24 hours and returned to baseline by 72 hours. T1 relaxation time increased most significantly between baseline and 24 hours and then decreased to near baseline level between 48 and 72 hours. T2 changes over time were not statistically significant. The type of localized, distinctive decreases in MR signal intensity occurring in clinical cases of early nontraumatic femoral head osteonecrosis was not observed in pigs. Such changes appear to require the presence of an intact and vigorous repair response within adjacent viable bone. However, the transient decrease in signal intensity and prolongation of T1 relaxation time at 12, 24, and 48 hours after traumatic vascular insult may be indicators of early femoral head ischemia.     

Bone marrow edema syndrome associated with uterine myoma: a case report

A patient with bone marrow edema syndrome of the hip associated with a uterine myoma is presented. A 51-year-old woman could not walk because of severe pain in both hips and had been referred to the authors' institute. Magnetic resonance imaging scans showed abnormal intensity on T1- and T2-weighted images in both femoral heads and a large mass arising from the uterus which was diagnosed as a uterine myoma. A 99mTc-methylene diphosphonate scintigraph showed diffuse uptake in both femoral heads. The pain in both hips decreased shortly after a hysterectomy and the patient could walk without crutches within 2 weeks after the gynecologic surgery. Magnetic resonance imaging scans taken 8 months after surgery showed high signal intensity on T1- and T2-weighted images, indicating normal bone marrow in the femoral heads. To the authors' knowledge, this is the first case report showing a bone marrow edema syndrome of the hip associated with uterine myoma. The pathophysiologic mechanisms for bone marrow edema syndrome of the hip in the current patient and in pregnancy may be identical. More specifically, a large intrapelvic mass may cause an increase of intrapelvic pressure and subsequent blood stasis in both conditions. The current case suggests the possible factors of bone marrow edema syndrome of the hip which need to be investigated.     

The transitory bone marrow edema syndrome of the hip

AIM OF THE STUDY: Since MRI-studies had begun to establish the diagnosis of transitory bone marrow edema syndrome of the hip orthopedic surgeons have tried to integrate this new syndrome into the internationally accepted system of musculoskeletal diseases. Particularly, the relation to non-traumatic osteonecrosis of the femoral head and the possibilities in therapy were investigated in our clinical trial. METHODS: Our clinical trial encompassed 106 patients suffering from the transitory bone marrow edema syndrome diagnosed in our department between the years 1985 and 2000. In order to confirm this diagnosis we used the patients' histories, their clinical courses, MRI studies, scintigraphic bone scans, intraosseal pressure measurements, phlebographies, laboratory data, and histologic specimens. One half of our collective positive for transient bone marrow edema of the hip underwent core-decompression surgery (50 patients), the other half (56 patients) was treated conservatively by analgesic medication combined with restriction of weight-bearing in the affected extremity. RESULTS: Patients positive for transitory bone marrow edema syndrome of the hip are middle-aged individuals with a male to female predominance of 60 : 40. This group has no or only few risk factors usually associated with osteonecrosis of the femoral head. Thus, the missing alcoholic abuse is striking. All patients suffering from transitory bone marrow edema syndrome of the hip recovered completely independent of the therapy we initiated and none of them showed any signs of osteonecrosis. The one half undergoing surgical decompression of the edema by using a 4.5 mm drill experienced an markedly accelerated relief of their clinical symptoms as well as their signal changes on MRI studies. Conventional X-ray pictures and scintigraphic bone scans are not useful for early differentiation between early stages of osteonecrosis and bone marrow edemas. This also accounts for the historical measurements of intraosseal pressure determinations and phlebographies. In contrast to that, MRI studies are effective in early differentiation between osteonecrosis and bone marrow edema syndrome of the hip, especially when contrast medium (gadolinium) is administrated intravenously and fat-suppressed MRI-sequences find use. Beginning osteonecrosis of the femoral head shows a segmental loss of contrast medium, a "double line sign" interface to the intact bone marrow, and only in a few cases they are associated with a huge symptomatic edema. The histologic examination of specimens obtained from 43 patients with transitory bone marrow edema syndrome of the hip revealed no signs of osteonecrosis. CONCLUSION: MRI studies are useful in differentiation between bone marrow edema syndrome of the hip and non-traumatic osteonecrosis of the femoral head in each stage of these two diseases. The thorough differentiation between these two diseases is of extraordinary importance for the clinical work-up of the patients as well as for scientific reasons. The course of primary bone marrow edema is benign as it results in entire recovery. The core decompression surgery offers the chance to shorten the course of the disease.     

Nonspecific findings on MR imaging. The importance of correlative studies and clinical information

Although magnetic resonance (MR) imaging is highly sensitive for the detection of abnormalities of the musculoskeletal system, changes in marrow and soft-tissue signal intensity are often nonspecific, and benign conditions may be mistaken for malignancy. In an effort to identify the cause of this type of misdiagnosis in MR examinations, the MR scans were reviewed of 30 patients whose images manifested bone and/or soft-tissue changes that were initially believed to be consistent with malignancy but were later found to represent benign conditions. Of the 30 patients, MR abnormalities were attributable to trauma in 11, benign tumors and tumorlike conditions in ten, infection in seven, and prior radiotherapy in two. In 24 cases, correlative imaging studies (14 patients), appropriate clinical history (six patients), and/or physical and laboratory examinations (four patients) would have avoided these misdiagnoses.     

Three cases of regional migratory osteoporosis

We examined three patients with regional migratory osteoporosis. Radionucleotide bone scanning and MRI was helpful in the diagnosis of this disease, and all patients recovered with conservative treatment. A biopsy of the femoral head, which was performed in one case, demonstrated bone marrow edema without osteonecrosis. A low intensity area of subchondral bone was observed on a T1-weighted image in two cases, as well as a fracture of the subchondral bone, which might be associated with transient osteoporosis. In one case, the affected region migrated from the medial femoral condyle to the lateral femoral condyle in the same knee joint.     

Histological findings of bone marrow edema pattern on MRI in osteonecrosis of the femoral head

Sequential magnetic resonance imaging (MRI) was performed on a 38-year-old woman with systemic lupus erythematosus who had received corticosteroid and had developed non-traumatic osteonecrosis of the femoral head. The initial MR finding was a band lesion on the T1-weighted image, which had been present before the onset of symptoms. At the onset of symptoms, a diffuse bone marrow edema pattern, with a low signal intensity on T1 and high signal intensity on T2-weighted images, was noted around the band lesion, extending to the femoral neck. Histopathologically, this region was found to consist of serous exudate, focal interstitial hemorrhage, and mild fibrosis, without any evidence of extension of osteonecrosis. It should be noted that extension of a low signal intensity area on MRI after the onset of hip pain may not be the result of the extension of osteonecrosis, but may represent concomitant edema due to collapse. Received: February 25, 2000 / Accepted: May 16, 2000     

髋部暂时性骨质疏松症的诊断与保守治疗

目的 探讨暂时性骨质疏松症的诊断方法及保守治疗疗效.方法 回顾性分析2006年10月至2009年7月收治的10例暂时性骨质疏松症患者的临床资料,对其临床表现、体格检查及影像学特征进行归纳.男4例,女6例;年龄22～43岁,平均35岁.所有女性患者均不在妊娠期内.2例髋关节正侧位X线片表现正常,8例表现为股骨头不同程度的骨质疏松,骨小梁模糊.MRI均表现为广泛均匀的信号改变,累及股骨头和股骨颈,其中7例病变同时出现在股骨转子周围.T1加权像表现为低信号,T2加权像表现为高信号.治疗方法包括避免重体力劳动、过量运动、长距离行走及采用药物治疗,药物包括非甾体抗炎镇痛药和二膦酸盐类药物.采用四点口述分级疼痛评分和Harris髋关节评分对治疗结果进行评价.结果 10例均获得随访,随访时间1.0～3.5年,平均2.5年.治疗1天后临床症状开始改善,治疗前疼痛评分为3级8例、4级2例,治疗6个月后为1级6例、2级3例、3级1例.治疗前Harris髋关节评分65～85分,平均74.5分;治疗6个月后84～100分,平均96分.治疗6个月后,X线片及MRI影像均基本恢复正常.结论 暂时性骨质疏松症是一种一过性、自限性疾病,有独特的临床及影像学特征.保守和支持疗法对暂时性骨质疏松症有效.     

Magnetic resonance imaging and histopathology in femoral head necrosis

We correlated preoperative magnetic resonance (MR) images and histopathology of eight femoral heads from patients with osteonecrosis. The signal intensity of the MR image was low in the area where fibrovascular tissue, disintegrated fibrovascular tissue, or amorphous necrotic material occupied the medullary space. On the other hand, the necrotic marrow without revascularization showed high signal intensity. Osteonecrosis can be detected by MR imaging as soon as a certain amount of bone marrow is replaced by fibrovascular tissue.     

Stress osteopathy of the femoral head: 10 military recruits followed for 5-11 years

I present 10 cases of spongious bone injury of the femoral head induced by physical stress. All patients were young military recruits who complained of hip pain from weight bearing which had started during physical exertion. Increased uptake in a radionuclide bone scan was regarded as the criterion for stress osteopathy. 7 hips were radiographically normal. In 3 cases a subcortical lateral cystic lesion of the femoral head was observed. MRI was performed in 6 cases. A decreased signal intensity in T1-weighted images in 5 cases and high signals in T2-weighted and IR signals (2 patients) indicated bone marrow edema. A lateral osteophyte of the femoral head developed in 1 case during 8 years' follow-up. After a median of 6 years, 9 patients still had occasional slight hip pain.     

Magnetic resonance imaging and histopathology in femoral head necrosis

We correlated preoperative magnetic resonance (MR) images and histopathology of eight femoral heads from patients with osteonecrosis. The signal intensity of the MR image was low in the area where fibrovascular tissue, disintegrated fibrovascular tissue, or amorphous necrotic material occupied the medullary space. On the other hand, the necrotic marrow without revascularization showed high signal intensity. Osteonecrosis can be detected by MR imaging as soon as a certain amount of bone marrow is replaced by fibrovascular tissue.     

The pattern of bone marrow oedema on MRI in osteonecrosis of the femoral head

It has been suggested that transient osteoporosis or the bone marrow oedema syndrome (BMOS) may be the initial phase of osteonecrosis of the femoral head (ONFH) and that there may be a common pathophysiology. In this study, we have assessed the MR images of 200 consecutive patients with ONFH in respect of the BMO pattern in order to test this hypothesis. This pattern was not observed in the early stage of ONFH. The initial abnormal finding detected on the MR images was an abnormal band of intensity at the junction between the necrotic area and the normal bone. Structural damage of the head seems to result in the appearance of the BMO pattern and the development of pain in ONFH. There was no finding to support the existence of a continuum between BMOS and ONFH.