MRI evaluation of steroid- or alcohol-related osteonecrosis of the femoral condyle

Subchondral insufficiency fracture of the knee: review of current concepts and radiological differential diagnoses

Subchondral insufficiency fracture of the knee (SIFK) is a common cause of knee joint pain in older adults. SIFK is a type of stress fracture that occurs when repetitive and excessive stress is applied to the subchondral bone. If the fracture does not heal, the lesion develops into osteonecrosis and results in osteochondral collapse, requiring surgical management. Because of these clinical features, SIFK was initially termed "spontaneous osteonecrosis of the knee (SONK)" in the pre-MRI era. SONK is now categorized as an advanced SIFK lesion in the spectrum of this disease, and some authors believe the term "SONK" is a misnomer. MRI plays a significant role in the early diagnosis of SIFK. A subchondral T2 hypointense line of the affected condyle with extended bone marrow edema-like signal intensity are characteristic findings on MRI. The large lesion size and the presence of osteochondral collapse on imaging are associated with an increased risk of osteoarthritis. However, bone marrow edema-like signal intensity and osteochondral collapse alone are not specific to SIFK, and other osteochondral lesions, including avascular necrosis, osteochondral dissecans, and osteoarthritis should be considered. Chondral lesions and meniscal abnormalities, including posterior root tears, are also found in many patients with SIFK, and they are considered to be related to the development of SIFK. We review the clinical and imaging findings, including the anatomy and terminology history of SIFK, as well as its differential diagnoses. Radiologists should be familiar with these imaging features and clinical presentations for appropriate management.

Predictive value of magnetic resonance imaging for multifocal osteonecrosis screening associated with glucocorticoid therapy

Objectives: The goals of this study were to elucidate the distribution of multifocal osteonecrosis associated with glucocorticoid therapy using magnetic resonance imaging (MRI) and to establish a MRI screening method.Methods: Between 1986 and 2018, 107 patients underwent MRI screening of their hips, knees, shoulders and ankle joints (856 joints in total) after systemic glucocorticoid therapy.Results: Osteonecrosis was observed in hip (68%), knee (44%), ankle (17%) and shoulder (15%) joints. Patients with bilateral osteonecrosis in their hips were likely to have bilateral osteonecrosis in their knees, whereas patients without osteonecrosis in both hips were unlikely to have osteonecrosis in both knees (p = .0299). Osteonecrosis was never evident in the ankle or shoulder joints when a patient did not have osteonecrosis in both hip and knee joints.Conclusion: In this study, MRI - as a screening method for multifocal osteonecrosis associated with glucocorticoid therapy - showed the sites affected first are hips and knees followed by ankles and shoulders. If osteonecrosis is absent in hip and knee joints, further screening of the ankles and shoulders is unnecessary. Any osteonecrosis observed in the hip and/or the knee joints warrants a second MRI screening of the ankles and shoulders.

The relationship between apolipoprotein genes polymorphisms and susceptibility to osteonecrosis of the femoral head: a meta-analysis

Background

The objective of this study was to evaluate whether apolipoprotein gene polymorphisms confer susceptibility to osteonecrosis of the femoral head (ONFH).

Methods

The relevant literature was screened from databases of Pubmed, Embase, Wanfang, Weipu and China National Knowledge Internet (CNKI) until May, 2017. In addition, odds ratio (OR) and its corresponding 95% confidence interval (CI) were used as a measure of effect size for calculating effect size.

Results

Totally, six case-control studies were included in this meta-analysis. It revealed that ApoB-C7623T polymorphism frequency was increased in ONFH group than in control group under three genetic models, including allele model (T vs. C, OR = 4.5149, 95% CI: 1.6968–12.0134); additive model (TC vs. CC, OR = 6.2515, 95% CI: 2.0939–18.6640); and dominant model (TT + TC vs. CC, OR = 5.4998, 95% CI: 1.9246–15.7163). In addition, the increased risk of ONFH were related to ApoA1-rs1799837 polymorphism under additive model (AA vs. GG, OR = 1.4175, 95% CI: 1.0522–1.9096) and recessive model (AA vs. GG + AG, OR = 1.7727, 95% CI: 1.3399–2.3452). However, four ApoB rs1042031, rs693, 3’-VNTR and G12619A polymorphisms under the all genetic models were not associated with susceptibility to ONFH.

Conclusion

The T allele and TC genotype of ApoB-C7623T and AA genotype of ApoA1-rs1799837 may contribute to increase the risk of ONFH.

Osteochondral Lesions of the Knee: Differentiating the Most Common Entities at MRI

Several pathologic conditions may manifest as an osteochondral lesion of the knee that consists of a localized abnormality involving subchondral marrow, subchondral bone, and articular cartilage. Although understanding of these conditions has evolved substantially with the use of high-spatial-resolution MRI and histologic correlation, it is impeded by inconsistent terminology and ambiguous abbreviations. Common entities include acute traumatic osteochondral injuries, subchondral insufficiency fracture, so-called spontaneous osteonecrosis of the knee, avascular necrosis, osteochondritis dissecans, and localized osteochondral abnormalities in osteoarthritis. Patient demographics, the clinical presentation, and the role of trauma are critical for differential diagnosis. A localized osteochondral defect can be created acutely or can develop as an end result of several chronic conditions. MRI features that aid in diagnosis include the location and extent of bone marrow edema, the presence of a fracture line, a hypointense area immediately subjacent to the subchondral bone plate, and deformity of the subchondral bone plate. These findings are essential in diagnosis of acute traumatic injuries, subchondral insufficiency fracture, and its potentially irreversible form, spontaneous osteonecrosis of the knee. If the lesion consists of a subchondral region demarcated from the surrounding bone, the demarcation should be examined for completeness and the presence of a "double-line sign" that is seen in avascular necrosis or findings of instability, which are important for proper evaluation of osteochondritis dissecans. Subchondral bone plate collapse, demonstrated by the presence of a depression or a fluid-filled cleft, can be seen in advanced stages of both avascular necrosis and subchondral insufficiency fracture, indicating irreversibility. Once the diagnosis is established, it is important to report pertinent MRI findings that may guide treatment of each condition. ^©RSNA, 2018 An earlier incorrect version of this article appeared online. This article was corrected on August 23, 2018.

Osteonecrosis of the Knee After Anterior Cruciate Ligament Reconstruction: A Report of 5 Cases

Background:

Anterior cruciate ligament (ACL) reconstruction is performed commonly, with a low risk of complication. Osteonecrosis of the knee is a potentially devastating condition and has been observed both spontaneously and after meniscectomy, although osteonecrosis has not been described as a complication after ACL reconstruction.

Purpose:

To describe the development of osteonecrosis of the knee in 5 patients after arthroscopic ACL reconstruction.

Study Design:

Case series; Level of evidence, 4.

Methods:

This study involved 5 patients (mean age, 33.2 years) who developed osteonecrosis of the knee after ACL reconstruction. A retrospective chart review was performed to identify clinical characteristics and surgical factors present in each of the 5 cases.

Results:

In 4 cases, the pathologic changes were present in both the medial and lateral femoral condyles, with isolated lateral condyle changes in the other case. The mean time to diagnosis was 11.6 months. These patients underwent an average of 1.8 additional surgical procedures after the diagnosis of osteonecrosis.

Conclusion:

Osteonecrosis of the knee is a rare outcome after ACL reconstruction. We are unable to identify clear risk factors for the development of this complication, although we hope the presentation of these cases will help promote the identification of other cases in future studies.

Glucocorticoid-induced avascular bone necrosis: diagnosis and management

Glucocorticoid use is one of the most important causes of avascular bone necrosis (AVN). The pathogenesis of glucocorticoid-induced AVN is not fully understood but postulated mechanisms include fat hypertrophy, fat emboli and intravascular coagulation that cause impedance of blood supply to the bones. Data regarding the relationship between AVN and dosage, route of administration and treatment duration of glucocorticoids are conflicting, with some studies demonstrating the cumulative dose of glucocorticoid being the most important determining factor. Early recognition of this complication is essential as the prognosis is affected by the stage of the disease. Currently, there is no consensus on whether universal screening of asymptomatic AVN should be performed for long-term glucocorticoid users. A high index of suspicion should be exhibited for bone and joint pain at typical sites. Magnetic resonance imaging (MRI) or bone scintigraphy is more sensitive than plain radiograph for diagnosing early-stage AVN. Conservative management of AVN includes rest and reduction of weight bearing. Minimization of glucocorticoid dose or a complete withdrawal of the drug should be considered if the underlying conditions allow. The efficacy of bisphosphonates in reducing the rate of collapse of femoral head in AVN is controversial. Surgical therapy of AVN includes core decompression, osteotomy, bone grafting and joint replacement. Recent advances in the treatment of AVN include the use of tantalum rod and the development of more wear resistant bearing surface in hip arthroplasty.

The incidence of alcohol-associated osteonecrosis of the knee is lower than the incidence of steroid-associated osteonecrosis of the knee: an MRI study

OBJECTIVE

The purpose of the study was to clarify the incidence of alcohol-associated osteonecrosis of the knee using MRI.

METHODS

A total of 131 patients (56 women and 75 men) with osteonecrosis of the femoral head were enrolled; 60 patients had a history of alcohol abuse and 71 had previously received steroids. All patients underwent MRI of the knee. The incidence of alcohol-associated osteonecrosis of the knee was compared with that of steroid-associated osteonecrosis of the knee. Predictive factors of alcohol- and steroid-associated osteonecrosis of the knee were also evaluated.

RESULTS

The incidence of alcohol-associated osteonecrosis of the knee was lower than that of steroid-associated osteonecrosis of the knee (18.3 vs 54.9%; P < 0.001, Fisher's exact probability test). No significant difference in weekly alcohol consumption was observed between patients with osteonecrosis of the knee and those without osteonecrosis of the knee. No significant difference in daily maximum steroid doses was observed between patients with osteonecrosis of the knee and those without osteonecrosis of the knee.

CONCLUSION

The present study revealed that the incidence of alcohol-associated osteonecrosis of the knee is lower than that of steroid-associated osteonecrosis of the knee.

Osteonecrosis in children after therapy for malignancy

OBJECTIVE

Osteonecrosis in the growing population of childhood cancer survivors results from disease and treatment. Imagers must be knowledgeable about patient groups at risk for its development, patterns of involvement and potential implications. This review will focus on implications of this potentially life-altering toxicity.

CONCLUSION

Childhood cancer survivors are at increased risk for developing osteonecrosis. Because osteonecrosis is often asymptomatic until late in the process, imaging is critical for its detection and characterization when interventions may be most effective to ameliorate its progression.

How does osteonecrosis about the knee progress in young patients with leukemia?: a 2- to 7-year study

BACKGROUND

Osteonecrosis is a major treatment complication of pediatric leukemias owing to its potential to cause joint deterioration. Because of potential long-term effects of osteonecrosis on joints, information regarding its progression and collapse in different patients can be used to identify high-risk groups, advise the patients and parents of this complication, and potentially consider the risk for development of osteonecrosis in planning primary treatment.

QUESTIONS/PURPOSES

We therefore determined: (1) the incidence of joint collapse and/or pain in young patients with hematologic malignancies diagnosed with ON of the knee; (2) risk factors associated with collapse; and (3) the relationship between size and location of osteonecrotic knee lesions and the likelihood of joint collapse.

PATIENTS AND METHODS

We retrospectively reviewed 109 patients with hematologic malignancies and MRI-confirmed knee osteonecrosis. The median age was 11.5 years (range, 2.3-18.8 years) at primary diagnosis of hematologic malignancy and a median age of 13.4 years (range, 2.7-23.3 years) at diagnosis of osteonecrosis of the knee. For analyses, we used the first and last MR images. Minimum clinical followup was 2.3 years after diagnosis of knee osteonecrosis (median, 6 years; range, 2.3-7.17 years).

RESULTS

Joint collapse occurred in 22% (24 of 109). Older age, pain at osteonecrosis presentation, and lesions extending to the articular surface of distal femoral epiphyses were associated with joint collapse.

CONCLUSIONS

Younger patients and those without extensive femoral epiphyseal involvement have a better prognosis for osteonecrosis of the knee.

LEVEL OF EVIDENCE

Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Complications following radiosynoviorthesis in osteoarthritis and arthroplasty: osteonecrosis and intra-articular infection

OBJECTIVES

In the literature, radiosynoviorthesis (RSO) has been associated only with a small number of complications. There is a trend towards increasing the use of RSO in diverse indications. After repeatedly observing several complications following RSO, a retrospective evaluation was undertaken to estimate the safety of this method.

METHODS

Between 1995-2007, we evaluated the outcome of RSO in 93 patients (143 knees, seven hips, seven shoulders, three elbows, one ankle) who presented to our orthopaedic department after joint treatment with yttrium-90((90)Y) or Rhenium-186((186)Re) colloid in an external nuclear medicine institution.

RESULTS

Seventy-nine of the 93 RSO treated patients had advanced primary or secondary osteoarthritis (OA), 12 had an arthroplasty. In seven cases, rheumatoid arthritis (RA) was responsible for secondary OA. The benefit in pain relief, as self-reported by the patients was low. Twenty-two of the 93 patients showed complications following RSO. We observed osteonecrosis (ON) in 19 and infection in five patients, including two with both complications. These findings were proven clinically, radiologically, intraoperatively, microbiologically and histologically. Statistical analysis revealed a strong correlation of arthroplasty to infection (rho=0.798, alpha=0.01), and a strong correlation of chronic obstructive pulmonary disease (COPD) and RA to ON following RSO (rho=0.674, alpha=0.01). Diabetes mellitus (DM) was also significantly correlated to ON after RSO treatment (rho=0.488,alpha=0.05).

CONCLUSIONS

Our data suggest that RSO may not be as safe as it has previously been reported, especially in advanced OA and arthroplasty.

Osteonecrosis in kidney recipients: has hypocalcaemia a role?

In a previous study, the musculoskeletal affections among kidney recipients (KR) were reported, with 63 KR suffering from joint affections. We sought to determine the prevalence of osteonecrosis (ON) among those KR with joint affections, its distribution among the affected joints, and possible risk predictors. KR were subjected to biochemical, haematological, and hepatitis serology estimations. Radiographic and magnetic resonance imaging were performed. Relevant data were retrieved from Patient Information System. Fourteen KR were suffering from ON, with an incidence of 22.2% in KR with joint affections and 12.0% in the target population of KR. The femoral head was affected in 57.1% and the femoral condyles in 28.6%. Hypocalcaemia was observed in KR with ON. Whether hypocalcaemia is a causative or associative of ON yet remains to be decided in forthcoming studies.

Extent of osteonecrosis on MRI predicts humeral head collapse

Although MRI is useful for predicting progression of osteonecrosis (ON) of the femoral head or femoral condyle, predicting outcome of atraumatic osteonecrosis of the humeral head using MRI has not been previously examined. We asked whether the prognosis was related to the extent and location of necrotic lesions on MRI. We investigated 46 radiographically noncollapsed humeral heads in 27 patients, 24 steroid-related and three alcohol-related, using MRI and serial radiographs. The minimum followup was 24 months (mean, 84.9 months; range, 24-166 months). The necrotic lesion was typically located at the medial and superior aspect of the humeral head. The necrotic angle, which expressed the extent of the necrotic lesion, was measured on midoblique-coronal plane (range; 0 degrees -134.7 degrees ) and on midoblique-sagittal plane (range; 0 degrees -150.6 degrees ). Of the 46 lesions, 34 were less than 90 degrees and did not collapse, whereas 11 of the other 12 lesions of more than 90 degrees (92%) collapsed within 4 years. Of these 11 collapsed lesions, four of less than 100 degrees did not progress, followed by reparative reaction on plain radiographs, whereas the other seven of more than 100 degrees progressed to osteoarthritis. The extent of a necrotic lesion on MRI is useful to predict collapse of the humeral head.

MR imaging of osteonecrosis of the knee in children with acute lymphocytic leukemia

This essay illustrates various patterns of progression of osteonecrosis of the knee and the relationship between early MR imaging findings and radiologic outcome in children with acute lymphocytic leukemia. It also includes a review of nonosteonecrosis signal abnormalities, which are common in the knee region and are often transient. Such abnormalities must be distinguished from osteonecrosis, which can lead to joint collapse and predispose to secondary arthritis.

Spontaneous regression of steroid-related osteonecrosis of the knee

It is unknown whether lesions of steroid-related osteonecrosis of the knee increase or decrease in size during the course of the disease after diagnosis. We sought to determine whether steroid-related osteonecrosis of the knee would have spontaneous changes in size, and if so, the factors affecting the change. We performed baseline and followup (minimum of 1 year) magnetic resonance imaging scans on 30 knees of 17 patients. We then used image registration techniques to match two sets of images. Lesion size change was evaluated on all contiguous pairs of matched magnetic resonance images. Fourteen Stage 1 (preradiographic stage) knees in seven patients showed spontaneous incomplete regression without subsequent collapse. These patients had early steroid-related lesions detected within 3 years after starting steroid treatment and all showed bilateral and multifocal involvement; lesion regression occurred regardless of location. The initial size and location of the lesions and discontinuing steroid administration did not seem to affect regression. Regression can occur in some patients with early steroid-related osteonecrosis of the knee, and the time between initiation of steroid treatment and its diagnosis might be the most significant predictive factor.

Application of 3D-MR image registration to monitor diseases around the knee joint

PURPOSE

To estimate the accuracy and consistency of a method using a voxel-based MR image registration algorithm for precise monitoring of knee joint diseases.

MATERIALS AND METHODS

Rigid body transformation was calculated using a normalized cross-correlation (NCC) algorithm involving simple manual segmentation of the bone region based on its anatomical features. The accuracy of registration was evaluated using four phantoms, followed by a consistency test using MR data from the 11 patients with knee joint disease.

RESULTS

The registration accuracy in the phantom experiment was 0.49+/-0.19 mm (SD) for the femur and 0.56+/-0.21 mm (SD) for the tibia. The consistency value in the experiment using clinical data was 0.69+/-0.25 mm (SD) for the femur and 0.77+/-0.37 mm (SD) for the tibia. These values were all smaller than a voxel (1.25 x 1.25 x 1.5 mm).

CONCLUSION

The present method based on an NCC algorithm can be used to register serial MR images of the knee joint with error on the order of a sub-voxel. This method would be useful for precisely assessing therapeutic response and monitoring knee joint diseases; normalized cross-correlation; accuracy.

MR imaging of epiphyseal lesions of the knee: current concepts, challenges, and controversies

This article focuses on spontaneous painful conditions involving the subchondral bone and marrow of mature knee epiphyses. MR imaging is the technique of choice for the work-up of these lesions and enables distinction of two main categories of lesions on the basis of T1-weighted images: avascular necrosis, and lesions presenting the bone marrow edema pattern. This latter category encompasses spontaneous osteonecrosis of the knee, and a variety of self-resolving conditions that may be differentiated by the study of the subchondral bone marrow area on T2-weighted images. Behind definite appellation of lesions, the challenge for the radiologist is to provide a prognosis: the distinction between self-resolving lesions from those that may evolve to epiphyseal collapse and joint impairment should be possible in most cases.

Osteonecrosis of Hip and Knee in Patients with Severe Acute Respiratory Syndrome Treated with Steroids

PURPOSE

To evaluate whether there is a relationship between steroid treatment and risk for osteonecrosis of the hip and knee in patients with severe acute respiratory syndrome (SARS).

MATERIALS AND METHODS

The hospital ethics committee approved the study, and all patients provided written informed consent. A total of 254 patients with confirmed SARS treated with steroids underwent evaluation with magnetic resonance (MR) imaging for osteonecrosis. Clinical profiles, joint symptoms, relevant past medical and drug history, steroid dose, and radiographic and MR imaging evidence of osteonecrosis and other bone abnormalities were evaluated. Mann-Whitney, Kruskal-Wallis, and Pearson exact chi(2) tests were performed, and univariate and multivariate logistic regression analyses were applied.

RESULTS

One hundred thirty-four (53%) of 254 patients had recent onset of large joint pain, but 211 (80%) of 264 painful joints were not associated with abnormality on MR images. MR images in 12 (5%) of 254 patients showed evidence of subchondral osteonecrosis in the proximal femur (n = 9), distal femur (n = 2), and proximal and distal femora and proximal tibiae (n = 1). Additional nonspecific subchondral and intramedullary bone marrow abnormalities were present in 77 (30%) of 254 patients. Results of multiple logistic regression analysis confirmed cumulative prednisolone-equivalent dose to be the most important risk factor for osteonecrosis. The risk of osteonecrosis was 0.6% for patients receiving less than 3 g and 13% for patients receiving more than 3 g prednisolone-equivalent dose. No relationship was found between additional nonspecific bone marrow abnormalities and steroid dose.

CONCLUSION

An appreciable dose-related risk was found for osteonecrosis in patients receiving steroid therapy for SARS. Additional nonspecific bone marrow abnormalities were frequent. Joint pain was common after SARS infection and was not a useful clinical indicator of osteonecrosis.

Regional migratory osteoporosis: a review illustrated by five cases

Regional migratory osteoporosis is an uncommon self-limiting disease characterized by an arthralgia which migrates between the weight-bearing joints of the lower limb. The radiological features of the disease obtained by conventional radiography, CT, MRI and radionuclide scintigraphy are illustrated by means of five case reports. These range from the most common presentation of sequential, proximal to distal spread in the lower limb to the rare intra-articular form, and disease involving the axial skeleton is also recognized. Clinical and radiographical features often overlap with those of diseases such as transient osteoporosis of the hip and transient bone marrow oedema syndrome, which is reflected in confusing terminology. Histological sampling is usually unnecessary; the radiological features are characteristic and the histological findings are not specific. Regional migratory osteoporosis is associated with systemic osteoporosis. This association is probably under-recognized, and has implications for the pathophysiology of the disease and for treatment.

MRI of osteonecrosis

Osteonecrosis is a relatively common condition, which may be idiopathic or secondary to a variety of clinical situations. It may involve the subarticular region of a joint, when it is commonly referred to as ischaemic necrosis, or the metaphyseal regions of long bones, when it is referred to as bone infarction. In both situations, early lesions may be radiographically occult. However, magnetic resonance imaging (MRI) is very sensitive in identifying and characterizing osteonecrosis. This review illustrates the varied MRI features of osteonecrosis that enable a confident diagnosis to be made. Complications and differential diagnosis are also considered.

Tacrolimus may be associated with lower osteonecrosis rates after renal transplantation

To compare the effect of two immunosuppressive agents, cyclosporin A and tacrolimus, in terms of the development of osteonecrosis after renal transplantation, a cohort study was done. The cyclosporin A group and the tacrolimus group consisted of 32 patients each, and were matched for age, gender, and renal allograft (cadaveric or living). Four patients with osteonecrosis of the femoral head and one patient with osteonecrosis of the knee were observed in the cyclosporin A group, whereas none of the patients in the tacrolimus group had osteonecrosis. All five patients with osteonecrosis were diagnosed on magnetic resonance imaging within 2 years after renal transplantation, and were followed up for more than 3 years after diagnosis. Significant differences were observed in the number of patients with acute rejection (cyclosporin A, 16 patients versus tacrolimus, seven patients). Significant differences also were found in the dose of pulse corticosteroids at 2 weeks (cyclosporin A, 1161.1 +/- 939.6 mg versus tacrolimus, 674.3 +/- 587.5 mg) and 4 weeks after transplantation (1727.5 +/- 1399.9 mg versus 965.0 +/- 861.9 mg). The risk of osteonecrosis after renal transplantation was reduced in the patients who used tacrolimus for immunosuppression, which reduced the number of acute rejection episodes and the dose of pulse corticosteroid administration.

Juxta-articular bone marrow signal changes on magnetic resonance imaging following arthroscopic meniscectomy

PURPOSE

Postmeniscectomy osteonecrosis of the knee has been reported in the past decade but the etiology remains unclear. Some investigators have indicated that bone marrow signal changes evident on magnetic resonance imaging (MRI) could be early warning signs of osteonecrosis. The purpose of this study was to determine the incidence rate, location, and magnitude of such changes in bone marrow of the knee after arthroscopic meniscectomy, using MRI.

TYPE OF STUDY

Cohort analytic study.

METHODS

Ninety-three patients with no bone marrow signal abnormalities on preoperative MRI were examined after isolated arthroscopic meniscectomy. There were 51 men and 42 women with an age range of 11 to 62 years (mean, 36.6 years). Of the total, 57 patients underwent partial meniscectomy (34 medial and 23 lateral) and the others total meniscectomy (10 medial and 26 lateral). MRI examinations were performed independently of postoperative knee symptoms, 1 to 24 months after surgery. Bone marrow changes of the treated knees were evaluated by T1- and T2*-weighted MRI.

RESULTS

Thirty-two of 93 patients (34%) had bone marrow signal changes in femoral or tibial condyles shown on postoperative MRI. No patients had these changes in the femoral or tibial condyles opposite from the meniscectomy side and, in the majority of cases, the size was less than half that of the condyle. Fifteen of the 44 patients who underwent medial meniscectomy and 17 of the 49 patients who underwent lateral meniscectomy had such changes. The meniscectomy side did not affect the incidence rate, and frequently both femoral and tibial condyles were involved. Age, gender and articular cartilage condition at the surgery were not risk factors. In contrast, the extent of meniscectomy affected the incidence rate.

CONCLUSIONS

This study suggests a positive correlation between arthroscopic meniscectomy and postoperative bone marrow signal changes of the knee.

Bone scintigraphy for osteonecrosis of the knee in patients with non-traumatic osteonecrosis of the femoral head: comparison with magnetic resonance imaging

OBJECTIVE

To determine whether technetium bone scintigraphy (BS) is useful for screening of non-traumatic osteonecrosis of the knee (ONK), which was a major affected site, secondary to the femoral head, among multiple osteonecrosis, in patients with non-traumatic osteonecrosis of the femoral head (ONFH).

METHODS

A total of 214 knee joints in 107 patients with ONFH were evaluated by BS and a comparison made with magnetic resonance imaging (MRI). ONK was classified into five sites, including the femoral condyles (ONFC), distal femoral metaphysis (ONFM), tibial plateau (ONTP), proximal tibial metaphysis (ONTM), and patella (ONP).

RESULTS

Based on the diagnosis by MRI, ONK was detected in 103 knees of 62 patients (48%). ONFC was most common (86 knees, 40%), ONFM (15%), followed by ONTM (10%), ONP (3%), and ONTP (0.9%). Sensitivity, specificity, and accuracy of BS for ONFC detection were 63%, 71%, and 68%, respectively. When the ONFC lesions on the coronal views of MRI were large or medium sized and occupied two thirds, or the entire anteroposterior joint surface on the sagittal views, the sensitivity of BS for ONFC detection increased to 89% (34/38 knees). The sensitivity of BS for ONFM, ONTM, and ONP detection was 3%, 0%, and 0%, respectively, but these lesions showed a low likelihood of collapse.

CONCLUSION

BS is useful for screening large ONK in patients with ONFH given that 89% of patients with ONFC who had a high risk of collapse of the knee were identified.

Osteonecrosis of the patella in patients with nontraumatic osteonecrosis of the femoral head: MRI findings in 60 patients

We examined both knees in 60 patients with nontraumatic osteonecrosis of the femoral head with three-dimensional MRI. We found osteonecrosis of the patella in 9 patients (10 knees) and osteonecrosis of the femoral or tibial condyles/metaphyses in 35 patients (61 knees). In the patella, the necrosis was located in the proximal half and tended to develop in patients with other necrotic lesions in the knee.

Osteonecrosis after lung transplantation: cystic fibrosis as a potential risk factor

BACKGROUND

Osteonecrosis is a known complication after transplantation of solid organs. The incidence of osteonecrosis after lung transplantation is not well documented.

METHODS

We investigated the incidence of symptomatic osteonecrosis in lung transplant recipients, transplanted between November 1992 and June 1998 at our institution. For the detection of osteonecrosis, all patients complaining of musculoskeletal pain underwent magnetic resonance imaging. Demographic characteristics, time after transplantation, etiology of underlying lung disease, and the number of steroid pulses for rejection episodes were compared for patients with and without osteonecrosis.

RESULTS

Of 63 transplant recipients, all 49 with a follow-up of >3 months were included for analysis. Of seven symptomatic transplant recipients, five cases of osteonecrosis (10%) were detected at a median duration of 216 days (range 44-600) after transplantation. Patients with osteonecrosis have been treated with the same immunosuppressive regimen and with an equal number of steroid pulses for acute rejection episodes (1.4+/-1.1 vs. 1.4+/-1.5, P=0.69), but were younger (26+/-8 vs. 40+/-11 years, P<0.01) than other transplant recipients. Symptomatic osteonecrosis was detected in four of 14 patients (29%) with cystic fibrosis (CF), compared with one osteonecrosis among 35 patients (3%) with other underlying diseases (P<0.02). Within the group of CF patients, specific clinical and demographic characteristics correlating with the risk for subsequent osteonecrosis could not be found.

CONCLUSION

In lung transplant recipients, CF may be a risk factor for the development of symptomatic osteonecrosis.