Stephanie L. Gold

MRI Predicts ALVAL and Tissue Damage in Metal-on-Metal Hip Arthroplasty

BackgroundAdverse local tissue reactions (ALTR) around metal-on-metal (MOM) hip arthroplasties are increasingly being recognized as a cause of failure. These reactions may be associated with intraoperative tissue damage and complication rates as high as 50% after revision. Although MRI can identify ALTR in MOM hips, it is unclear whether the MRI findings predict those at revision surgery.Questions/purposesWe therefore (1) identified which MRI characteristics correlated with histologically confirmed ALTR (using the aseptic lymphocytic vasculitis-associated lesions [ALVAL] score) and intraoperative tissue damage and (2) developed a predictive model using modified MRI to detect ALVAL and quantify intraoperative tissue damage.MethodsWe retrospectively reviewed 68 patients with failed MOM hip arthroplasties who underwent preoperative MRI and subsequent revision surgery. Images were analyzed to determine synovial volume, osteolysis, and synovial thickness. The ALVAL score was used to grade tissue samples, thus identifying a subset of patients with ALTR. Intraoperative tissue damage was graded using a four-point scale. Random forest analysis determined the sensitivity and specificity of MRI characteristics in detecting ALVAL (score ≥ 5) and intraoperative tissue damage.ResultsMaximal synovial thicknesses and synovial volumes as determined on MRI correlated with the ALVAL score and were higher in cases of severe intraoperative tissue damage. Our MRI predictive model showed sensitivity and specificity of 94% and 87%, respectively, for detecting ALVAL and 90% and 86%, respectively, for quantifying intraoperative tissue damage.ConclusionsMRI is sensitive and specific in detecting ALVAL and tissue damage in patients with MOM hip implants. MRI can be used as a screening tool to guide surgeons toward timely revision surgery.Level of EvidenceLevel III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

MRI of Hip Cartilage: Joint Morphology, Structure, and Composition

BackgroundAccurate, reproducible, and noninvasive assessment of hip cartilage is clinically relevant and provides a means by which to assess the suitability of candidates for arthroscopic or open surgical procedures and the response to such interventions over time. Given the relatively thin cartilage of the hip and the complex spherical anatomy, however, accurately assessing the cartilage poses a challenge for traditional MRI techniques.Questions/PurposesWe assessed the current status of imaging articular cartilage of the hip through a comprehensive review of recent literature.MethodsWe performed a literature review using PubMed. Topics included quantitative MRI, imaging of the hip cartilage and labrum, femoroacetabular impingement syndrome, and osteoarthritis of the hip.Where Are We Now?With the use of high in-plane and through-plane resolution, reproducible assessment of hip cartilage and labrum is clinically feasible. More recent quantitative MR techniques also allow for noninvasive assessment of collagen orientation and proteoglycan content in articular cartilage, thus providing insight into early matrix degeneration. These techniques can be applied to cohorts at risk for osteoarthritis, helping to predict cartilage degeneration before symptoms progress and osteoarthritic changes are visible on radiographs.Where Do We Need to Go?Prospective longitudinal data registries are necessary for developing predictive models of osteoarthritis and subsequent joint failure to assess the results of surgical intervention and predict the timing of arthroplasty.How Do We Get There?By establishing more hip cartilage registries, a correlation can be made between subjective measures and morphologic MRI to assess the cartilage, labrum, bone, and synovial lining of the hip.

MRI Findings in Painful Metal-on- Metal Hip Arthroplasty

OBJECTIVE The objective of our study was to compare the frequency of osseous and soft-tissue abnormalities in patients presenting with hip pain after resurfacing arthroplasty and after total hip arthroplasty (THA), correlate the MRI findings with histologic results, and determine which MRI findings are predictive of aseptic lymphocytic vasculitis-associated lesions. MATERIALS AND METHODS The MRI examinations of patients with metal-on-metal hip prostheses placed at resurfacing arthroplasty (n=31) or THA (n=29) were reviewed for osteolysis, synovitis, extracapsular disease, synovial pattern, and mode of decompression into adjacent bursae. Regional muscles and tendons were assessed for tendinosis, tear, atrophy, and edema. Histologic and operative findings were reviewed in 19 patients (20 hips) who underwent revision surgery. Chi-square tests were performed to detect differences between the resurfacing arthroplasty and THA groups. The Wilcoxon rank sum test was performed to detect differences in MRI findings in patients with and those without aseptic lymphocytic vasculitis-associated lesions. RESULTS Synovitis was detected in 77.4% of resurfacing arthroplasty hips and 86.2% of THA hips. Extracapsular disease was present in 6.5% of resurfacing arthroplasty hips and 10.3% of THA hips. Osteolysis was detected in 9.7% of resurfacing arthroplasty hips and 24.1% of THA hips. There was no difference in the incidence of synovitis (p=0.51), osteolysis (p=0.17), or extracapsular disease (p=0.67) between the resurfacing arthroplasty and THA groups. Patients with aseptic lymphocytic vasculitis-associated lesions had higher volumes of synovitis (p=0.04) than patients without aseptic lymphocytic vasculitis-associated lesions. Extracapsular disease and muscle edema were seen only in patients with aseptic lymphocytic vasculitis-associated lesions. CONCLUSION Synovitis is common in patients with metal-on-metal hip prostheses and occurs with a similar incidence after resurfacing arthroplasty and after THA; osteolysis and extracapsular disease are uncommon. The MRI signs most suggestive of aseptic lymphocytic vasculitis-associated lesions are high volumes of synovitis, extracapsular disease, and intramuscular edema.

MR Imaging of Adverse Local Tissue Reactions around Rejuvenate Modular Dual-Taper Stems

PURPOSE To describe the magnetic resonance (MR) imaging characteristics associated with adverse local tissue reactions and tissue damage around hip arthroplasties in which the recalled Rejuvenate modular dual-taper stem was used. MATERIALS AND METHODS The institutional review board of the Hospital for Special Surgery approved the study. All study patients provided informed consent. MR imaging studies were retrospectively reviewed in a cohort of 58 patients with 66 hip arthroplasties with Rejuvenate stems who had presented for imaging evaluation because of recall of the implant. Multiple regression analysis was used to examine MR imaging features, biomechanical factors, and metal ion levels as predictors of aseptic lymphocytic vasculitis-associated lesion (ALVAL) score at histologic assessment while adjusting for age and sex for 54 revised hips. RESULTS Revision surgery was performed in 54 hips on the basis of clinical or imaging findings (24% of hips were completely asymptomatic). The median ALVAL score among the revised hips was 9 (range, 1-10). Imaging characteristics observed with high frequency in patients with ALVAL included synovitis, mixed- or solid-type synovitis, synovial thickening, and capsular dehiscence. CONCLUSION MR imaging provides an effective noninvasive method for assessing the presence and severity of adverse local tissue reaction, as well as the degree of pre-existing tissue damage, thereby facilitating early and accurate identification of candidates for revision surgery.

High-Resolution Magnetic Resonance Imaging of the Lower Extremity Nerves

Magnetic resonance (MR) imaging of the nerves, commonly known as MR neurography is increasingly being used as noninvasive means of diagnosing peripheral nerve disease. High-resolution imaging protocols aimed at imaging the nerves of the hip, thigh, knee, leg, ankle, and foot can demonstrate traumatic or iatrogenic injury, tumorlike lesions, or entrapment of the nerves, causing a potential loss of motor and sensory function in the affected area. A thorough understanding of normal MR imaging and gross anatomy, as well as MR findings in the presence of peripheral neuropathies will aid in accurate diagnosis and ultimately help guide clinical management.

Magnetic resonance imaging of the wrist: Bone and cartilage injury

Magnetic resonance imaging (MRI) is particularly useful for imaging the wrist due to its superior soft tissue contrast and ability to detect subtle bone marrow changes and occult fractures. A high field (1.5T or greater) strength, dedicated wrist coil, and high in‐plane and through‐plane resolution must be utilized to successfully visualize the relatively thin cartilage of the wrist. MRI can be used to detect occult carpal bone fractures, identify complications following scaphoid fractures, and assess for avascular necrosis in the setting in Kienböcks and Preisers disease. MRI is useful to identify secondary soft tissue and chondral pathology in impaction/impingement syndromes. The use of an intermediate‐echo time fast spin echo sequence allows for accurate assessment of articular cartilage, allowing evaluation of chondral wear in the setting of primary osteoarthritis and posttraumatic degenerative arthrosis. MRI is the most sensitive imaging modality for the detection of early inflammatory arthropathies and can detect synovitis, bone marrow edema, and early erosions in the setting of negative radiographs. J. Magn. Reson. Imaging 2013;37:1005–1019.

Imaging of Sports-Related Midfoot and Forefoot Injuries

Sports-related injuries of the foot are common and may result in significant morbidity, particularly if inaccurate or delayed diagnosis leads to improper management. While less common than injuries of the ankle, sports-related foot injuries account for 2% to 18% of athletic injuries. Injury may occur as a result of acute trauma or chronic overuse, and high-impact sports that involve running, jumping, or contact place the athlete at higher risk for injury. Accurate and timely diagnosis of injury is the key to proper management, and diagnostic imaging studies often play a critical role in this regard. While radiographs, computerized tomography scans, and ultrasound are useful in the evaluation of the foot, magnetic resonance imaging provides superior tissue contrast as well as the ability to detect stress reaction in bone that precedes discernible fracture line on radiographs, allowing accurate detection of both osseous and soft tissue pathology. This review focuses on imaging of common sports-related injuries of the midfoot and forefoot, including osseous, ligamentous, and tendinous pathology, with emphasis on magnetic resonance imaging diagnosis.

Assessment of Reactive Synovitis in Rotating-Platform Posterior-Stabilized Design: A 10-Year Prospective Matched-Pair MRI Study

This is the first long-term (mean 11.6 years), prospective, matched-pair study (based on age, gender, BMI and UCLA scores) using MAVRIC (multi-acquisition variable-resonance image combination) magnetic resonance imaging to analyze reactive synovitis and osteolysis between rotating-platform posterior-stabilized (RP-PS), fixed-bearing metal-back (FB-MB), and all-polyethylene tibial (APT) in active patients (24 total, 8 in each group, mean age of 64 years, mean UCLA of 8.5) with identical femoral component and polyethylene. Reactive synovitis was observed in 6 RP-PS (75%), all 8 FB-MB (100%), and 6 APT (75%). There was a significant difference between the RP-PS and FB-MB knees in volumetric synovitis (P=0.023). Osteolysis with bone loss more than 4mm was seen in 3 FB-MB, 2 APT and none for RP-PS. These were not statistically significant.

Magnetic Resonance Imaging and Clinical Evaluation of Chondral lesions treated with Allografts Juvenile Cells

Objectives: The De Novo NT graft (®)(natural tissue) (Zimmer, Warsaw, IN) is a new technique that consists of a scaffold free allogeneic juvenile cartilage. The purpose of this study is to describe the first cases performed in our institution with De Novo NT (®) assessing both clinical outcomes and magnetic resonance imaging. Methods: 17 patients with focal patella femoral cartilage lesions treated with De Novo NT (®) were prospectively followed. The mean age at the time of surgery was 30 years. Clinical assessment was performed with the International Knee Documentation Committee (IKDC), KOOS and MARX at baseline and most recent follow up. Magnetic resonance imaging, including T2 relaxation time maps and T1 rho in six patients, was used to evaluate the cartilage repair morphologic characteristics in 12 patients. Results: Fifteen patients met the study criteria with a mean follow up of 12 months (±3). The mean defect size was 217±100 mm. In 11 cases the lesion was in the patella, 3 in the trochlea and one in both patella and trochlea. Mean improvement in preoperative to postoperative score was significant for the IKDC objective score 45.8 (±28) to 73.3 (±24) (p=.009), IKDC pain score 49.1 (±20) to 69.8 (±23) (p=.003), KOOS 53.5 (±21) to 75.5 (±15) (p=.001), IKDC subjective 41.3 (±21.7) to 72.7 (±15) (p=.004). MRI demonstrated only two cases (16%) with graft hypertrophy. There was only one case with a detached graft. Mild and moderate subchondral edema was present in 90% (11 patients) of the cases. At the interface between the repaired tissue and the native cartilage, there were only two cases with a fissure of more than 2mm. Very good (66 to 100%) and good (between 33-66%) cartilage fill was present in 54% of the cases. Mild synovial reaction was present in 58% of the cases. From the 6 patients with T2 mapping, all repairs showed significantly different prolongation of quantitative T2 values in both the superficial and deep components of the repair tissue (47.18 for repair vs 28.3 for native (p=0.005) in the deep area and 58.6 for repair vs 37.4 for native in the superficial area (p=0.02). (Figure 1). Conclusion: De Novo NT® appears to be an effective treatment for patello-femoral chondral lesions, with significant improvement in the short-term clinical follow up. The MRI indicated implant stability with peripheral integration in most cases. As the implanted cells are allogeneic, synovial reaction is a parameter that should be considered. Only 5 patients had moderate synovial reaction, which did not affect the graft. Quantitative T2 mapping showed stratification of T2 values suggesting maturation to hyaline cartilage.

Magnetic Resonance Imaging of the Hip Labrum, Capsule, and Synovium

Magnetic resonance imaging (MRI) is the imaging modality of choice in the preoperative and postoperative assessment of patients undergoing hip arthroscopy. MRI offers high soft tissue contrast, sensitivity to fluid, and direct multi-planar acquisition and avoids exposure to ionizing radiation. With attention to scan parameters, accurate and reproducible imaging can be obtained allowing for precise assessment of the labrum, capsule, synovium, and cartilage. The MRI appearance of the labrum, capsule, and synovium is discussed with reference to the most common pathologies encountered at hip arthroscopy.