MAGNETIC RESONANCE IMAGING OF BONE MARROW DISORDERS OF THE KNEE

Comparison of cone-beam and fan-beam computed tomography and low-field magnetic resonance imaging for detection of palmar/plantar osteochondral disease in Thoroughbred horses

BACKGROUND

Palmar/plantar osteochondral disease (POD) of the metacarpal/tarsal condyles is a common pathological finding in racehorses.

OBJECTIVE

To compare diagnoses, imaging details, and measurements of POD lesions between cone-beam computed tomography CT (CBCT), fan-beam CT (FBCT), and low-field magnetic resonance imaging (MRI) using macroscopic pathology as a gold standard.

STUDY DESIGN

Cross-sectional study.

METHODS

Thirty-five cadaver limbs from 10 horses underwent CBCT, FBCT, MRI, and macroscopic examination. CT and MR images were examined for presence of POD, imaging details of POD, and measurements of POD dimensions and areas. Imaging diagnoses, details, and measurements were compared with macroscopic examination and between modalities.

RESULTS

Forty-eight POD lesions were seen over 70 condyles. Compared with macroscopic examination the sensitivity and specificity of diagnosis were 95.8% (CI95 = 88%-99%) and 63.6% (CI95 = 43%-81%) for FBCT, 85.4% (CI95 = 74%-94%) and 81.8% (CI95 = 63%-94%) for CBCT, and 69.0% (CI95 = 54%-82%) and 71.4% (CI95 = 46%-90%) for MRI. Inter-modality agreement on diagnosis was moderate between CBCT and FBCT (κ = 0.56, p < 0.001). POD was identified on CT as hypoattenuating lesions with surrounding hyperattenuation and on MRI as either T1W, T2*W, T2W, and STIR hyperintense lesions or T1W and T2*W heterogeneous hypointense lesions with surrounding hypointensity. Agreement on imaging details between CBCT and FBCT was substantial for subchondral irregularity (κ = 0.61, p < 0.001). Macroscopic POD width strongly correlated with MRI (r = 0.81, p < 0.001) and CBCT (r = 0.79, p < 0.001) and moderately correlated with FBCT (r = 0.69, p < 0.001). Macroscopic POD width was greater than all imaging modality (p < 0.001).

MAIN LIMITATIONS

Effect of motion artefact in live horse imaging could not be assessed.

CONCLUSIONS

All imaging modalities were able to detect POD lesions, but underestimated lesion size. The CT systems were more sensitive, but the differing patterns of signal intensity may suggest that MRI can detect changes associated with POD pathological status or severity. The image features observed by CBCT and FBCT were similar.

Relationship between the size of bone marrow edema of the talus and ankle pain

BACKGROUND

We sought to determine the changes in the size of the edema observed on MRI scans and its relation to the patient's pain during activity and pain during rest in bone marrow edema.

METHODS

A total of 26 patients were followed up at 3-month intervals for a period of 1 year. During the follow-ups, magnetic resonance imaging scans of the patients' ankles were obtained; the scores obtained on the American Orthopaedic Foot and Ankle Society functional rating scale and visual analog scale were determined. The changes in these parameters and the correlation between them were examined.

RESULTS

The size of the edema as observed on magnetic resonance imaging scans decreased, and the pain during activity and rest decreased. Although there is a correlation between the decrease in the edema size observed on magnetic resonance imaging scans and decrease in the pain during activity, there is no correlation between the decrease in the edema size observed on magnetic resonance imaging scans and the decrease in pain during rest.

CONCLUSIONS

Patients can be informed more precisely, that the pain during rest and activity may not decrease after the third and sixth month, respectively. Magnetic resonance imaging may not alter after the ninth month, so it may not be necessary to be performed again.

Painful lateral knee condyle bone marrow edema after treatment with lateral wedged insole

A 50-yr-old man arrived at our department for a rehabilitation prescription after a right knee medial collateral ligament sprain. Magnetic resonance imaging showed medial collateral ligament partial rupture and medial femoral condyle increased signal intensity indicating bone edema. After treatment, the patient still complained of weight-bearing knee medial compartment pain. A lateral wedged insole was prescribed to decrease medial compartment compression forces. Initial response to insole use was good, but soon after, the patient complained of severe worsening knee pain. On examination, the lateral joint line and condyle palpation were tender. Insole use discontinuation was recommended, and another magnetic resonance imaging scan was performed. It showed an high T2-weighted signal intensity, representing bone marrow edema comprising a volume of 5 x 5 x 4.5 cm of lateral femoral condyle. Discontinuation of orthosis use relieved the pain, and the edema disappeared. To our knowledge, lateral femoral condyle painful bone marrow edema after lateral wedged insole use has not been previously described. The findings of this case report indicate that lateral wedged insole prescription should be carefully evaluated.

The relationship between bone marrow edema size and knee pain

The purpose of our study was to determine the changes in the size of the edema observed on MRI scans and its relation to the activity pain of the patient and the rest pain in bone marrow edema (BME). A total of 51 patients were followed up at 3-month intervals for a period of 1 year. During the follow-ups, MRI scans of the patients' knees were obtained; the scores obtained on the Stanmore functional rating scale and visual analog scale were determined. The changes in these parameters and the correlation between them were examined. The following are the observations recorded during the bone marrow edema follow-ups: the size of the edema as observed on MRI scans decreased, and the activity pain and the rest pain decreased. While there is a correlation between the decrease in the edema size observed on MRI scans and decrease in the activity pain, there is no correlation between the decrease in the edema size observed on MRI scans and the decrease in rest pain. No changes were observed after a particular period of time with regard to decrease in the edema size observed on MRI scans, decrease in activity pain, and decrease in rest pain in follow-ups of BME patients.

Bone marrow edema syndrome

Bone marrow edema syndrome (BMES) refers to transient clinical conditions with unknown pathogenic mechanism, such as transient osteoporosis of the hip (TOH), regional migratory osteoporosis (RMO), and reflex sympathetic dystrophy (RSD). BMES is primarily characterized by bone marrow edema (BME) pattern. The disease mainly affects the hip, the knee, and the ankle of middle-aged males. Many hypotheses have been proposed to explain the pathogenesis of the disease. Unfortunately, the etiology of BMES remains obscure. The hallmark that separates BMES from other conditions presented with BME pattern is its self-limited nature. Laboratory tests usually do not contribute to the diagnosis. Histological examination of the lesion is unnecessary. Plain radiographs may reveal regional osseous demineralization. Magnetic resonance imaging is mainly used for the early diagnosis and monitoring the progression of the disease. Early differentiation from other aggressive conditions with long-term sequelae is essential in order to avoid unnecessary treatment. Clinical entities, such as TOH, RMO, and RSD are spontaneously resolving, and surgical treatment is not needed. On the other hand, early differential diagnosis and surgical treatment in case of osteonecrosis is of crucial importance.

Acute nontraumatic adult knee pain: the role of MR imaging

Acute nontraumatic pain in the adult knee can be seen in many settings, such as transient bone marrow oedema syndrome (TBMOS), regional migratory osteoporosis (RMO), spontaneous osteonecrosis (SONK) and insufficiency fractures. Early differentiation among them is crucial to avoid unnecessary treatment. TBMOS and RMO are considered to be self-limiting conditions without longterm sequelae. On the other hand, the clinical course of SONK is thought to be dependent on the size of osteonecrosis. Recent data suggest the term SONK is misleading one and should be replaced. Insufficiency fractures may demonstrate a similar clinical syndrome without a history of a single traumatic injury. The imaging pathway for knee pain has evolved considerably with the advent of magnetic resonance (MR) imaging, which is very sensitive in the early depiction of bone marrow oedema. Therefore, in patients with acute nontraumatic knee pain whose radiographs are negative or inconclusive, MR imaging is the method of choice for further evaluation. This article discusses the potential aetiologies and reviews MR imaging findings of the most common disorders afflicting the subchondral knee-joint area.

Risk of osteonecrosis of the femoral condyle after arthroscopic chondroplasty using radiofrequency: a prospective clinical series

Radiofrequency (RF) energy can be used for treatment of intraarticular pathologies in knee joint. RF energy was found to be superior to mechanical techniques in smoothening the articular surface (chondroplasty), shortening the operation time and reducing the blood loss. As RF produces thermal energy it has been reported to be responsible for the postoperative osteonecrosis however, there is no clinical evidence in the literature supporting that RF causes osteonecrosis. The current study searches for an answer whether surgical arthroscopic modalities using RF energy causes osteonecrosis. We hypothesize in the presented study that chondroplasty with RF has no effect on increasing the incidence of osteonecrosis in knee joint. In a prospective clinical trial, arthroscopic chondroplasty was performed in 50 patients with degenerative changes of the articular cartilage, stage II and III according to Outerbridge. To be included in the study, the patients had to meet the following criteria: (1) Preoperative MRI and plain film radiographs showing no evidence of osteonecrosis. (2) Patients had to be symptomatic for at least 6 weeks before the preoperative MRI. (3) Arthroscopically confirmed stage II or III. Preoperative MRI was taken in all patients. For chondral lesions bipolar RF energy system (VAPR-DePuy Mitek, Norwood, USA) was used. The patients were examined at the end of the sixth month and we performed MRI. Fifty patients with an average of age 45.54 (between 18 and 64) (SD, 10.63). During arthroscopy, together with chondropathy 22 patients pure medial meniscus tears, 7 patients medial and lateral meniscus tears, 7 patients pure lateral meniscus tears, 2 patients medial plica, and 3 patients synovial hypertrophy were detected. Among all 50 patients, osteonecrosis were detected at only 2 (4%) in the postoperative period. Until now it was not clear that RF energy causes osteonecrosis; however, according to this study if proper method is used, bipolar RF energy used for arthroscopic chondroplasty does not causes subchondral osteonecrosis.

Transient osteoporosis

Transient osteoporosis is characterized primarily by bone marrow edema. The disease most commonly affects the hip, knee, and ankle in middle-aged men. Its cause remains unknown. The hallmark that separates transient osteoporosis from other conditions presenting with a bone marrow edema pattern is its self-limited nature. Laboratory tests usually do not contribute to the diagnosis. Plain radiographs may reveal regional osseous demineralization. Magnetic resonance imaging is used primarily for early diagnosis and monitoring disease progression. Early differentiation from more aggressive conditions with long-term sequelae is essential to avoid unnecessary treatment. Clinical entities such as transient osteoporosis of the hip and regional migratory osteoporosis are spontaneously resolving conditions. However, early differential diagnosis and surgical treatment are crucial for the patient with osteonecrosis of the hip or knee.

Knochenmarködem im Kniegelenk

The Bone marrow edema (BME) is a common finding when evaluating patients with knee pain by magnetic resonance imaging (MRI). The typical signal patterns of BME are unspecific and can be found with different diseases of the knee. Since different therapeutic approaches are mandatory, differential diagnosis of the several forms of BME is important. In this review, painful BME will be separated into three different etiological groups. Group 1 ischemic BME: osteonecrosis, osteochondritis dissecans, bone marrow edema syndrome and complex regional pain syndrome. Group 2 mechanical BME: bone bruises, microfracture, stress-BME und stress fracture. Group 3 reactive BME: inflammatory gonarthritis, degenerative gonarthrosis, postoperative and tumours. The typical MRI morphologies and differential diagnosis of these BME manifestations will be described. The different therapeutic consequences will also be briefly mentioned.

The management of necrosis-associated and idiopathic bone-marrow oedema of the proximal femur by intravenous iloprost

Bone-marrow oedema can occur both in isolation and in association with necrosis of bone, but it has not been shown whether each respond to the same methods of treatment.

We treated 16 patients with isolated oedema and 17, in which it was associated with necrosis of the proximal femur, with the prostacyclin derivative iloprost, which has been shown to be effective in the idiopathic form. The Harris hip score, the range of movement, the extent of the oedema as measured by MRI, pain on a visual analogue scale and patient satisfaction were recorded before and subsequent to treatment.

In both groups, we were able to show a significant improvement (p < 0.001) in these observations during the period of follow-up indicating that iloprost will produce clinical improvement in both circumstances.

Painful bone marrow edema of the knee: differential diagnosis and therapeutic concepts

Bone marrow edema (BME) is a common finding when patients with knee pain are evaluated by MRI. The typical MRI signal patterns for BME are nonspecific, however. This article categorizes painful BME of the knee joint into three distinct etiologic groups and briefly describes therapeutic approaches for each of the 12 different types of BME.

Can bone marrow edema be seen on STIR images of the ankle and foot after 1 week of running?

PURPOSE

To evaluate whether initiation of running in sedentary individuals would lead to bone marrow edema on MR images, within the time span of 1 week.

MATERIALS AND METHODS

The feet of 10 healthy volunteers were imaged by MR imaging before and after running during 30 min a day for 1 week. The images were evaluated by consensus of 2 musculoskeletal radiologists who graded the presence of bone marrow edema on a 4-point scale. Edema scores and number of bones involved before and after running were compared statistically.

RESULTS

Edema was present on the baseline images in 3 subjects. After running edema showed an increase or was present in 5 subjects. The changes after running were statistically significant. Bones involved were the talus, calcaneus, navicular bone, cuboid bone, and 5th metatarsal.

CONCLUSION

Edema patterns can be seen in the feet of asymptomatic individuals. During initiation of running an increase of edema or development of new edema areas can be seen.