Magnetic resonance imaging signs of iliotibial band friction in patients with isolated medial compartment osteoarthritis of the knee

Background  The purpose of this retrospective study was to assess the frequency of magnetic resonance imaging (MRI) signs of iliotibial band friction (ITBF) in patients with advanced medial compartment knee osteoarthritis. Material and methods  Proton density-weighted (PDw) fat-saturated (fatsat) MR images (1.5 T, slice thickness (SL) 2.5–3 mm, eight-channel phased array coil) of 128 patients with isolated advanced osteoarthritis of the medial knee compartment and complete or subtotal (>80%) loss of cartilage were evaluated. There were 41 men and 87 women. Mean age was 63 years, range 34–89 years. The control group consisted of 94 patients with medial meniscus degeneration without cartilage loss (56 men and 38 women, mean age 50 years, range 16–89 years). MRI signs of ITBF were evaluated in both groups [poorly defined abnormalities of signal intensity and localized fluid collection lateral, distal or proximal to the lateral epicondyle; signal intensity abnormalities superficial to or deep by the iliotibial band (ITB)]. Transverse images were evaluated separately. Consensus evaluation using all imaging planes was performed. Results  Of 128 patients with osteoarthritis, 95 had moderate or advanced MRI signs of ITBF (74.2%). Eighty-nine patients (69.5%) had advanced degeneration of the meniscus. In the control group, 26 of 94 patients had only moderate MRI signs of ITBF. There was a statistically significant difference between both groups for the presence of MR signs of ITBF (P ≤ 0.01). Conclusion  MRI signs of ITBF were frequently present in patients with severe medial compartment osteoarthritis of the knee. Joint space narrowing with varus knee deformity may be a cause of ITBF. Level of evidence  Level 4 (Historic, non-randomized, retrospective, cohort study with a control group)     

Possible beneficial effect of bisphosphonates in osteonecrosis of the knee

Osteonecrosis (ON) in the knee occurs as a localized inflammatory disease in relation to spontaneous or non-traumatic ON. Conservative treatment possibilities are limited, and prognosis appears to be poor; in most cases, ON results in knee arthroplasty. Bisphosphonates are suggested to prevent bone resorption and collapse of necrotic bone. In this observational, prospective study we investigated the effect of bisphosphonate treatment in patients with spontaneous or arthroscopy-induced ON of the knee. Twenty-eight patients with osteonecrotic lesions and bone marrow oedema in the knee were included. In 22 patients (80%), ON was identified after arthroscopic surgery of the knee; six patients were diagnosed with spontaneous ON. Patients were initially given pamidronate 120 mg i.v. divided in 3–4 perfusions over 2 weeks, followed by oral bisphosphonate treatment with alendronate 70 mg weekly for 4–6 months. Bisphosphonate treatment resulted in a rapid pain relief, VAS decreasing from 8.2 ± 1.2 at baseline to 5.02 ± 0.6 after 4–6 weeks (p < 0.001). After 6 months, the VAS decreased by 80% (p < 0.001). At the 6-month follow-up, symptoms had resolved completely in 15 patients out of 28; in 6 patients, minimal symptoms (VAS 1–2) remained. In two patients, treatment effect was unsatisfactory, and surgical intervention was needed (arthroplasty). Bone marrow oedema on MRI resolved completely in 18 patients out of 28 with substantial reduction in the remaining. Furthermore, osteonecrotic area resolved completely or demarcation with sclerotic changes of the necrotic area could be observed. Bisphosphonate treatment in patients with osteonecrosis of the knee was associated with a rapid improvement in pain score and radiological consolidation of the area of osteonecrosis. Further randomized, controlled trials are warranted to confirm the potential beneficial role of bisphosphonates in the treatment of osteonecrosis of the knee. Level of evidence: observational study, level IV.     

Assessment of cartilage-dedicated sequences at ultra-high-field MRI: comparison of imaging performance and diagnostic confidence between 3.0 and 7.0 T with respect to osteoarthritis-induced changes at the knee joint

Objective  The objectives of the study were to optimize three cartilage-dedicated sequences for in vivo knee imaging at 7.0 T ultra-high-field (UHF) magnetic resonance imaging (MRI) and to compare imaging performance and diagnostic confidence concerning osteoarthritis (OA)-induced changes at 7.0 and 3.0 T MRI. Materials and methods  Optimized MRI sequences for cartilage imaging at 3.0 T were tailored for 7.0 T: an intermediate-weighted fast spin-echo (IM-w FSE), a fast imaging employing steady-state acquisition (FIESTA) and a T1-weighted 3D high-spatial-resolution volumetric fat-suppressed spoiled gradient-echo (SPGR) sequence. Three healthy subjects and seven patients with mild OA were examined. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), diagnostic confidence in assessing cartilage abnormalities, and image quality were determined. Abnormalities were assessed with the whole organ magnetic resonance imaging score (WORMS). Focal cartilage lesions and bone marrow edema pattern (BMEP) were also quantified. Results  At 7.0 T, SNR was increased (p < 0.05) for all sequences. For the IM-w FSE sequence, limitations with the specific absorption rate (SAR) required modifications of the scan parameters yielding an incomplete coverage of the knee joint, extensive artifacts, and a less effective fat saturation. CNR and image quality were increased (p < 0.05) for SPGR and FIESTA and decreased for IM-w FSE. Diagnostic confidence for cartilage lesions was highest (p < 0.05) for FIESTA at 7.0 T. Evaluation of BMEP was decreased (p < 0.05) at 7.0 T due to limited performance of IM-w FSE. Conclusion  Gradient echo-based pulse sequences like SPGR and FIESTA are well suited for imaging at UHF which may improve early detection of cartilage lesions. However, UHF IM-w FSE sequences are less feasible for clinical use.     

A 5-year prospective study of non-surgical treatment of retro-trochanteric pain

Diffuse retro-trochanteric pain occasionally radiating to the lower extremity could be caused by the piriformis or internal obturator muscle syndromes. Thirteen patients, with retro-trochanteric pain were included in the study. All patients suffered from a diffuse, but intense and often radiating hip pain. The median duration of the symptoms was 8 (1–20) years. The patients were treated by a specific supervised stretching programme with special emphasis on the internal obturator muscle. The duration of the stretching programme was 4 weeks. At inclusion, the median pain on the visual analogue scale (VAS) was 6.0 (3–7). The VAS for pain decreased to 4.0 (0–7) (p = 0.01) at 12 weeks. Five years after treatment, the VAS for pain was still significantly lower than at inclusion, 4.0 (0–7) (p = 0.018). A significant reduction in the number of positive Freiberg’s tests and in the number of patients limping was also observed, both at 3 months and at 5 years after treatment. It appears that a supervised stretching programme renders significant short and long term decrease in symptom for patients with retro-trochanteric pain.     

Direct magnetic resonance arthrography of the knee: utility of axial traction

The purpose of this study was to determine the impact of axial traction during acquisition of direct magnetic resonance (MR) arthrography examination of the knee in terms of joint space width and amount of contrast material between the cartilage surfaces. Direct knee MR arthrography was performed in 11 patients on a 3-T MR imaging unit using a T1-weighted isotropic gradient echo sequence in a coronal plane with and without axial traction of 15 kg. Joint space widths were measured at the level of the medial and the lateral femorotibial joint with and without traction. The amount of contrast material in the medial and lateral femorotibial joint was assessed independently by two musculoskeletal radiologists in a semiquantitative manner using three grades (‘absence of surface visualization, ‘partial surface visualization or ‘complete surface visualization’). With traction, joint space width increased significantly at the lateral femorotibial compartment (mean = 0.55 mm, p = 0.0105) and at the medial femorotibial compartment (mean = 0.4 mm, p = 0.0124). There was a trend towards an increased amount of contrast material in the femorotibial compartment with axial traction. Direct MR arthrography of the knee with axial traction showed a slight and significant increase of the width of the femorotibial compartment with a trend towards more contrast material between the articular cartilage surfaces.     

Soft tissue balancing in varus total knee arthroplasty: an algorithmic approach

We present an algorithmic release approach to the varus knee, including a novel pie crust release technique of the superficial MCL, in 359 total knee arthroplasty patients and report the clinical and radiological outcome. Medio-lateral stability was evaluated as normal in 97% of group 0 (deep MCL), 95% of group 1 (pie crust superficial MCL) and 83% of group 2 (distal superficial MCL). The mean preoperative hip–knee angle was 174.0, 172.1, and 169.5 and was corrected postoperatively to 179.1, 179.2, and 177.6 for groups 0, 1, and 2, respectively. A satisfactory correction in the coronal plane was achieved in 82.9% of all-comers falling within the 180° ± 3° interval. An algorithmic release approach can be beneficial for soft tissue balancing. In all patients, the deep medial collateral ligament should be released and otseophytes removed. The novel pie crust technique of the superficial MCL is safe, efficient and reliable, provided a medial release of 6–8 mm or less is required. The release of the superficial MCL on the distal tibia is advocated in severe varus knees. Preoperative coronal alignment is an important predictor for the release technique, but should be combined with other parameters such as reducibility of the deformity and the obtained gap asymmetry.     

Does running cause metatarsophalangeal joint effusions? A comparison of synovial fluid volumes on MRI in athletes before and after running

Objective  The metatarsophalangeal joints (MTPJ) are the only joints that bear weight directly through synovium. The purpose of this study was to determine whether there is an association between synovial stresses during running and increases in volume of joint fluid. Materials and methods  This was a prospective case controlled study (nine healthy athlete volunteers acting as own controls). High-resolution coronal 3D T2W magnetic resonance imaging of the MTPJs were obtained following 24 h rest and after a 30-min run. The volume of joint fluid in each MTPJ (n = 90) was measured by two independent observers using an automated propagating segmentation tool. Results  The median volume of synovial fluid in the MTPJs at rest was 0.018 ml (inter-quartile range (IQ) range 0.005–0.04) and after running 0.019 ml (IQ range 0.005–0.04, p = 0.34, 99% confidence interval (CI), 0.330.35). The volume of fluid in the MTPJs of the great toes was substantially larger than other toes (0.152 ml at rest, 0.154 ml after exercise, p = 0.903). Median volumes decrease from second to fifth MTPJs (0.032–0.007 ml at rest and 0.035–0.004 ml after exercise). Subset analysis for each toe revealed no significant difference in volumes before and after running (p = 0.39 to p = 0.9). The inter-rater reliability for observer measurements was good with an intra-class correlation of 0.70 (95% CI, 0.60 to 0.78). Conclusion  It appears to be normal to find synovial fluid, particularly in the MTPJs of the great toes, of athletes at rest and after running. There does not appear to be an association between moderate distance running and an increase in the volume of synovial fluid. This study was funded by a research grant from Action Arthritis.     

CT-based attenuation correction in 82Rb-myocardial perfusion PET–CT: incidence of misalignment and effect on regional tracer distribution

Purpose Misalignment of low-dose-CT used for attenuation correction (AC) may cause artifacts in cardiac-PET–CT. The aim was to evaluate incidence and severity of misalignment and its quantitative effects on regional myocardial ⁸²Rb-distribution. Methods Rest/dipyridamole ⁸²Rb-perfusion-PET–CT studies of 92 consecutive patients were analyzed for misalignment. Two different scanning protocols were employed: the first 57 patients had separate CTs for rest and stress PET. The following 35 patients had one CT at rest, used for AC of rest and stress PET. Misalignment was visually scored on a five-point scale (0 = no, 1 = minimal, 2 = mild, 3 = moderate, and 4 = severe). In five representative patients with normal perfusion and low probability of disease, 95 polarmaps were created by shifting CT vs PET prior to reconstruction of attenuation-corrected data sets using dedicated software (three dimensions of space; magnitude of shifts, 5, 10, 14 mm). Results PET/CT -misalignment was detected in 60% of rest and 67% of stress studies. Alignment for rest was better than that for stress (0.7 ± 0.7 vs 1.0 ± 0.9, P = 0.03). Comparison of the two protocols revealed no effect on the alignment of the stress study (1.0 ± 0.9 vs 1.0 ± 0.9, P = 0.9). Quantitatively, the largest individual effect of any artificial misalignment was a 25% reduction of relative ⁸²Rb uptake. With a shift of 1 cm, the largest effect in an individual was a 19% decrease. Anterior wall was most frequently influenced by misalignment, but changes of uptake also occurred in all other segments. Conclusions Misalignment between CT and PET in cardiac-PET–CT influences regional tracer distribution in multiple segments. Repeated CT imaging after dipyridamole does not improve alignment. These results emphasize the need for strategies to improve coregistration in clinical imaging protocols.     

Radiofrequency Ablation Therapy Combined with Cementoplasty for Painful Bone Metastases: Initial Experience

The purpose of this study was to assess the efficacy and safety of percutaneous radiofrequency (RF) ablation therapy combined with cementoplasty under computed tomography and fluoroscopic guidance for painful bone metastases. Seventeen adult patients with 23 painful bone metastases underwent RF ablation therapy combined with cementoplasty during a 2-year period. The mean tumor size was 52 × 40 × 59 mm. Initial pain relief, reduction of analgesics, duration of pain relief, recurrence rate of pain, survival rate, and complications were analyzed. The technical success rate was 100%. Initial pain relief was achieved in 100% of patients (n = 17). The mean VAS scores dropped from 63 to 24 (p < 0.001) (n = 8). Analgesic reduction was achieved in 41% (7 out of 17 patients). The mean duration of pain relief was 7.3 months (median: 6 months). Pain recurred in three patients (17.6%) from 2 weeks to 3 months. Eight patients died and 8 patients are still alive (a patient was lost to follow-up). The one-year survival rate was 40% (observation period: 1–30 months). No major complications occurred, but one patient treated with this combined therapy broke his right femur 2 days later. There was transient local pain in most cases, and a hematoma in the psoas muscle (n = 1) and a hematoma at the puncture site (n = 1) occurred as minor complications. Percutaneous RF ablation therapy combined with cementoplasty for painful bone metastases is effective and safe, in particular, for bulky tumors extending to extraosseous regions. A comparison with cementoplasty or RF ablation alone and their long-term efficacies is needed.     

Follow-up of pain processing recovery after ketamine in hyperalgesic fibromyalgia patients using brain perfusion ECD-SPECT

Purpose The aim of this study was to determine whether the follow-up of pain processing recovery in hyperalgesic fibromyalgia (FM) could be objectively evaluated with brain perfusion ethyl cysteinate dimer single photon computerized tomography (ECD-SPECT) after administration of ketamine. Materials and methods We enrolled 17 hyperalgesic FM women patients (48.5 ± 11 years, range 25–63). After treatment with subcutaneous ketamine, 11 patients were considered as “good responders”, with a decrease in pain intensity, evaluated by visual analog scale (VAS), greater than 50%. On the other hand, six patients were considered as “poor responders”. A voxel-based analysis of regional cerebral blood flow (rCBF) was conducted (p _voxel < 0.001uc), in the two subgroups of patients, before and after treatment, in comparison to a group of ten healthy subjects, matched for age and gender. Results In comparison to baseline brain SPECT, midbrain rCBF showed a greater increase after ketamine in the responder group than in the nonresponder group (p _cluster = 0.016c). In agreement with the clinical response, the change in midbrain rCBF after ketamine was highly correlated with the reduction of VAS pain score (r = 0.7182; p = 0.0041). Conclusion This prospective study suggests that blockade of facilitatory descending modulation of pain with ketamine can be evaluated in the periaqueductal grey with brain perfusion SPECT.     

MRI evaluation of anterior knee pain: predicting response to nonoperative treatment

Objective  Tibial tubercle lateral deviation and patellofemoral chondromalacia are associated with anterior knee pain (AKP). We hypothesized that increased tibial tubercle lateral deviation and patellofemoral chondromalacia on magnetic resonance imaging correlates with the presence of AKP and with failure of nonoperative management. Materials and methods  In this retrospective comparative study, a blinded musculoskeletal radiologist measured tibial tubercle lateral deviation relative to the trochlear groove in 15 controls, 15 physical therapy responders with AKP, and 15 physical therapy nonresponders with AKP. Patellar and trochlear cartilage was assessed for signal abnormality, irregularity, and defects. Results  The mean tibial tubercle lateral deviation in controls, physical therapy responders, and physical therapy nonresponders were 9.32 ± 0.68, 13.01 ± 0.82, and 16.07 ± 1.16 mm, respectively (data are mean ± standard deviation). The correlation coefficients for tubercle deviation, chondromalacia patellae, and trochlear chondromalacia were 0.51 (P < 0.01), 0.44 (P < 0.01), and 0.28 (P < 0.05), respectively. On analysis of variance, tubercle deviation and chondromalacia patellae contributed significantly to prediction of AKP and response to physical therapy. The presence of chondromalacia patellae and a tubercle deviation greater than 14.6 mm is 100% specific and 67% sensitive with a positive predictive value of 100% and negative predictive value of 75% for failure of nonoperative management. Conclusion  Subjects with AKP have more laterally positioned tibial tubercles and are more likely to have patellar chondromalacia. Patients with AKP, chondromalacia patellae, and a tubercle deviation greater than 14.6 mm are unlikely to respond to nonoperative treatment. Knowledge of tibial tubercle lateralization and presence of chondromalacia patellae may assist clinicians in determining patient prognosis and selecting treatment options.     

Clinical outcome after reconstruction for isolated posterior cruciate ligament injury

Fifty-one patients were operated with reconstruction for an isolated PCL injury from 1997 to 2005. Forty-three of these patients were followed during a median period of 48 months (17–109). Median time from injury to surgery was 18 months (2–368). Five patients were operated within the first 6 months after the injury. Nineteen patients had a BPTB autograft, 24 had a hamstring tendon autograft, and seven patients in the hamstring group had a double-bundle femoral fixation. Clinical assessment included Lysholm knee score, International Knee Documentation Committee 2000 (IKDC) scores, Cincinnati score, Tegner score, KOOS score, VAS score, stress radiographs, and a functional test. The median Lysholm score at follow-up was 80 (32–95). Median Tegner score before injury was 7 (1–10) and at follow-up 6 (0–9). Median Cincinnati and IKDC 2000 scores were 74 (12–100) and 63 (24–100), respectively. The mean VAS for subjective assessment of knee function was 67.6 (SD = 22.9). The radiologically measured difference in posterior tibial translation between operated and non-injured knees was mean 8.4 mm (SD = 4.8). Four different functional tests showed function of the operated leg from 92% (25–128) to 95% (15–124) compared to the opposite leg. This study shows good functional outcome after reconstruction for isolated rupture of the posterior cruciate ligament. However, pain and instability are still a problem, as only three patients reported full Lysholm subscore indicating full stability, and only four patients reported full subscore indicating no knee pain.     

Assessment of coronary flow reserve by sestamibi imaging in patients with typical chest pain and normal coronary arteries

Purpose We assessed coronary flow reserve (CFR) by sestamibi imaging in patients with typical chest pain, positive exercise stress test and normal coronary vessels. Methods Thirty-five patients with typical chest pain and normal angiogram and 12 control subjects with atypical chest pain underwent dipyridamole/rest ^99mTc-sestamibi imaging. Myocardial blood flow (MBF) was estimated by measuring first transit counts in the pulmonary artery and myocardial counts from SPECT images. Estimated CFR was expressed as the ratio of stress to rest MBF. Rest MBF and CFR were corrected for rate–pressure product (RPP) and expressed as normalised MBF (MBF_n) and normalised CFR (CFR_n). Coronary vascular resistances (CVR) were calculated as the ratio between mean arterial pressure and estimated MBF. Results At rest, estimated MBF and MBF_n were lower in controls than in patients (0.98 ± 0.4 vs 1.30 ± 0.3 counts/pixel/s and 1.14 ± 0.5 vs 1.64 ± 0.6 counts/pixel/s, respectively, both p < 0.02). Stress MBF was not different between controls and patients (2.34 ± 0.8 vs 2.01 ± 0.7 counts/pixel/s, p=NS). Estimated CFR was 2.40 ± 0.3 in controls and 1.54 ± 0.3 in patients (p < 0.0001). After correction for the RPP, CFR_n was still higher in controls than in patients (2.1 ± 0.5 vs 1.29 ± 0.5, p < 0.0001). At baseline, CVR values were lower (p < 0.01) in patients than in controls. Dipyridamole-induced changes in CVR were greater (p < 0.0001) in controls (−63%) than in patients (−35%). In the overall study population, a significant correlation between dipyridamole-induced changes in CVR and CFR was observed (r = −0.88, p < 0.0001). Conclusion SPECT might represent a useful non-invasive method for assessing coronary vascular function in patients with angina and a normal coronary angiogram.     

Osteochondral lesions of the humeral trochlea in the young athlete

Objective  The purpose of this study was to characterize the variety of osteochondral abnormalities of the humeral trochlea in the pediatric athlete. Materials and methods  Patients with trochlear abnormalities were identified through keyword search of radiology dictations from 1999 to 2007. The patient’s medical record, imaging studies, and surgical reports were reviewed. The osteochondral lesions were categorized based on the imaging appearance. Surgical results were reviewed in conjunction with the imaging findings. Results  Eighteen patients were identified. Trochlear lesions were stratified into two imaging groups: Osteochondral injury/osteochondritis dissecans (OCD) vs. avascular necrosis (AVN). The osteochondral injury group was stratified into medial and lateral trochlear abnormalities. The medial lesions (n = 3) were small (<6 mm) and were located on the posterior articular surface of the medial trochlea. The lateral lesions (n = 10) were larger (10–14 mm), circumscribed, and were located on the posterior inferior aspect of the lateral trochlea. Trochlear AVN (n = 5) affected development of the lateral trochlea (type A) or both the medial and lateral aspects of the trochlea (type B). AVN occurred exclusively in athletes with history of remote distal humeral fracture. Seven of the 18 patients underwent elbow arthroscopy. Surgical findings and treatment regimens are summarized. Conclusion  Trochlear lesions should be considered in throwing athletes presenting with medial elbow pain and flexion contracture/extension block. Medial trochlear osteochondral injuries may result from posteromedial olecranon abutment. Lateral OCD lesions occur in a characteristic vascular watershed zone resulting from the unique blood supply of the trochlea. Trochlear AVN may be unmasked years following treated distal humeral fracture when the athletic demands upon the adolescent elbow increase, revealing the altered growth and biomechanics.     

Treatment of tear of the anterior cruciate ligament combined with localised deep cartilage defects in the knee with ligament reconstruction and autologous periosteum transplantation

An acute tear of the anterior cruciate ligament (ACL) is frequently associated with injuries to the joint cartilage and subchondral bone. These injuries may progress to deep cartilage defects, causing disabling pain, and represent a therapeutic challenge in patients with the combination instability and pain. At our clinic we treat patients with the combined injury with simultaneous ACL reconstruction and autologous periosteum transplantation of the cartilage defect. This report describes the technique for periosteum transplantation of full-thickness cartilage defects in the medial femoral condyle. Our clinical report includes the first 7 patients (6 men and 1 woman, mean age 29.1 years at operation) who have been followed for 2 years or longer of 14 consecutive patients (12 men and 2 women). All patients had suffered a total tear of the ACL and a full-thickness defect of the cartilage at the medial femoral condyle. The cartilage defects had a mean area of 7.3 cm² (range 1.0–13.5 cm²). All patients had disabling instability and medial knee pain when walking. The anterior cruciate ligament was reconstructed with a bone-tendon-bone graft of the central third of the patellar ligament. After preparation of the cartilage lesion, the periosteum transplant was anchored to the underlying bone with suture anchors and fibrin glue. Postoperatively, these patients (n = 7) were initially treated with continuous passive motion, followed by active flexibility training and slowly progressing strength training and weight-bearing activities. At follow-up a mean of 31.3 months (range 24–38 months) later, 6 patients evidenced subjectively stable knees, no pain during rest or when walking, and had returned to not too heavy knee-loading work. One patient had a subjectively stable knee, but felt medial knee pain. Meticulous surgical technique and rigorous postoperative rehabilitation are probably of the greatest importance in this procedure. With the use of suture anchors and fibrin glue, the periosteum transplant can be well adapted to the condylar subchondral bone bed. Received: 14 April 1998 Accepted: 4 September 1998     

MRI features of tuberculosis of the knee

Objective  The objective of this study was to describe the magnetic resonance imaging (MRI) features of tuberculosis (TB) of the knee joint. Materials and methods  The MRI features in 15 patients with TB of the knee, as confirmed by histology of the biopsied joint synovium, were reviewed retrospectively. The images were assessed for intra-articular and peri-articular abnormalities. Results  All patients had florid synovial proliferation. The proliferating synovium showed intermediate to low T2 signal intensity. In the patients who were administered intravenous contrast, the hypertrophic synovium was intensely enhancing. Marrow edema (n = 9), osteomyelitis (n = 4), cortical erosions (n = 5), myositis (n = 6), cellulitis (n = 2), abscesses (n = 3), and skin ulceration/sinus formation (n = 2) were seen in the adjacent bone and soft tissue. Conclusion  Synovial proliferation associated with tuberculous arthritis is typically hypointense on T2-weighted images. This appearance, in conjunction with other peri-articular MRI features described, can help in distinguishing TB arthritis from other proliferating synovial arthropathies.     

Abnormal bone scans in anterior cruciate ligament deficiency indicate structural and functional abnormalities

Many patients with anterior cruciate ligament (ACL) deficiency have an abnormal bone scan. This finding has not yet been explained. Suggested explanations include intra-articular (structural) or kinematic (functional) abnormalities. We examined the relationship between bone scintigraphy and cartilage degeneration or meniscal lesions in the ACL-deficient knee in 95 consecutive patients who had bone scintigraphy 1–3 days prior to arthroscopic ACL reconstruction. Intra-articular abnormalities of the knee did not explain all scintigraphic patterns of this study. We did not find clinically useful positive predictive values for scintigraphic patterns considered to indicate cartilage degeneration or a lateral meniscus lesion. A clinically useful positive predictive value was found only for medial meniscus lesions when time since ACL rupture was more than 18 months, and for local cartilage degeneration when markedly increased uptake was seen when time since ACL rupture was more than 4 months. Considering these findings, alternative explanations are discussed, based on specific aspects of abnormal kinematics and adaptive bone metabolism of the ACL-deficient knee. Received: 15 October 1999/Accepted: 25 February 2000     

Measurement and comparison of the difference in normal medial and lateral knee joint opening

This paper reports the amount of medial and lateral knee joint opening in the general population. Knee joint lateral and medial opening at 20° knee flexion was quantified on manual varus and valgus stress test, respectively, with custom made device. One hundred men and women between the ages of 20–60 years were evaluated for their joint openings. Patients with previous knee surgeries or chronic knee pains were excluded from the study. Measurements were done twice by two different orthopedic surgeons who were blinded from each other. The mean age of the study group was 39 years (range 20–60 years) and 43 years for women (range 20–60 years) and 34 years for men (range 20–60). The mean lateral and medial knee joint space opening was 7.0° (range 3–9°) and 4.1° (range 2–7°), respectively, in the overall population; in the male population, it was 6.7° (range 3–9°) and 3.9° (range 2–7°), respectively, and in the female population, it was 7.2° (range 3–9°) and 4.3° (range 3–7°), respectively. Conversion to displacement in millimetres, the overall mean lateral and medial joint displacement was 9.3 mm (range 5.1–13.6 mm) and 4.8 mm (range 3.5–10.7 mm), respectively; for males, it was 9.1 (range 5.1–11.9 mm) and 4.6 mm (range 3.5–7.9 mm), respectively, for females, it was 9.8 mm (range 7.2–13.6 mm) and 4.9 mm (range 3.7–10.7 mm), respectively. The prevalence of the overall population that exceeds 6 mm or more lateral joint space opening was 91% (male 90% and female 92%) and medial joint space was 8% (male 4% and female 12%). Statistically, significant differences were seen between medial and lateral opening in male, female and the overall population (p<0.001). The female population exhibited wider opening in both medial and lateral joint opening than the male population (p<0.05). The interexaminer reliability showed no significant difference (p>0.05). More than 91% of the Korean population showed wide lateral joint space opening in the bilateral knee. However, none complained of functional instability or symptoms except for non-pathologic laxity detected by the physician. We strongly recommend bilateral comparison of the knee that has wide lateral joint opening.     

Small hypervascular hepatocellular carcinomas: value of “washout” on gadolinium-enhanced dynamic MR imaging compared to superparamagnetic iron oxide-enhanced imaging

The aim of this study was to retrospectively compare the value of “washout” on dynamic MR imaging with superparamagnetic iron oxide (SPIO)-enhanced imaging features of small hepatocellular carcinoma (HCC). A total of 74 small (5–30 mm) hypervascular HCCs in 42 cirrhotic patients who underwent double contrast material-enhanced MR imaging were evaluated to determine the presence of washout in the portal or equilibrium phase of gadolinium-enhanced dynamic imaging and decreased uptake of SPIO on T2*-weighted imaging. HCCs were verified histologically (n = 13) or by serial follow-up imaging studies (n = 61). According to the size of the lesions, 27 vs. 73% (<10 mm, n = 15; P = 0.016 on McNemar test), 39 vs. 79% (10–14 mm, n = 28; P = 0.002), 50 vs. 93% (15–20 mm, n = 14; P = 0.031), and 82 vs. 100% (>20 mm, n = 17; P = 0.250) of the lesions showed washout vs. decreased SPIO accumulation respectively. The larger the lesion, the higher the prevalence of washout or decreased SPIO uptake (P = 0.004 or P = 0.036, respectively, on Mantel-Haenszel test). In many small hypervascular HCCs up to 2 cm, SPIO-enhanced MR imaging offers essential information for early diagnosis in the absence of washout on dynamic imaging.