Lower Extremity Magnetic Resonance Imaging Research Articles

Primary Arthrodesis vs Open Reduction Internal Fixation for Lisfranc Fracture-Dislocations: A Cost Analysis

Category: Midfoot/Forefoot; Trauma Introduction/Purpose: Lisfranc fracture-dislocation is an uncommon but serious injury that currently lacks universal consensus on optimal operative treatment. Two common fixation methods are open reduction and internal fixation (ORIF) and primary arthrodesis (PA). The objective of this study is to analyze the cost difference between ORIF and PA of Lisfranc injuries, along with the contribution of medical services to overall costs. Methods: This was a retrospective cost analysis of the MarketScan database from 2010-2020. Patients undergoing primary ORIF (CPT code 28615) versus PA (28730 and 28740) for Lisfranc fracture-dislocation were identified. The primary independent variable was ORIF versus PA of Lisfranc injury. Costs accrued due to operative management was the primary objective, and was analyzed according to net payment, total payment, coinsurance, copayment, deductible, and coordination of benefits per savings (COB/savings) amounts. Outpatient surgery setting (hospital versus ambulatory surgical center (ASC)) and requirement for secondary arthrodesis within the primary ORIF group were secondary independent variables. The utilization of and costs contributed by medical services were secondary outcomes. These included outpatient clinic visits, foot radiographs, lower extremity magnetic resonance imaging (MRI), lower extremity computed tomography (CT), physical therapy (PT), and opioid prescriptions. Student’s t-test, chi-squared test, and Poisson multivariable regression were used for statistical analysis, with significance set as P < 0.05. Results: From 2010 to 2020, 7,268 patients underwent operative management of Lisfranc injuries, with 5,689 (78.3%) ORIF and 1,579 (21.7%) PA. Of those undergoing initial ORIF, 22 (0.39%) were converted to secondary arthrodesis at a mean ± standard deviation of 10.2 ± 12.1 months after the index surgery. PA was independently associated with increased net payment, total payment, and coinsurance. When compared to primary ORIF, patients undergoing PA utilized more clinic and PT visits and imaging sessions. However, primary ORIF with secondary arthrodesis was associated with more clinic visits, imaging, and generated higher costs from these medical services compared to PA alone. Within hospital and ASCs, PA was associated with increased net and total payments. However, out-of-pocket (OOP) costs were found to be higher in ASCs. Conclusion: Treatment of Lisfranc fracture-dislocation with PA is associated with higher initial costs compared to ORIF with subsequent secondary arthrodesis. Conversely, secondary arthrodesis demonstrated significantly higher costs and resource utilization compared to primary procedures. Specific cost drivers for PA and secondary arthrodesis were clinic visits and perioperative imaging.

Solitary bone plasmacytoma of the tibia presenting as chronic osteomyelitis: A rare case report and literature review.

Plasmacytoma is a rare plasma cell dyscrasia that grows within the axial skeleton or soft tissue structures as solitary or multiple masses. The primary types are solitary plasmacytoma, including solitary bone plasmacytoma (SBP) and solitary extramedullary plasmacytoma, and multiple solitary plasmacytomas. SBP is characterized by localized proliferation of monoclonal plasma cells and is rare. However, SBP with chronic osteomyelitis is even rarer. A 47-year-old man previously diagnosed with chronic osteomyelitis presented with repeated discharge and ulceration in the front of his right tibia. Lower extremity magnetic resonance imaging (MRI) and computed tomography (CT) examinations showed dead bone formation and surrounding inflammatory edema. Thus, the patient underwent dead bone excision and fenestration of the bone marrow cavity. The histopathologic examination results indicated plasmacytoma. Therefore, we administered radiotherapy with satisfactory results. Physicians should pay close attention to chronic osteomyelitis because it may be accompanied by plasmacytoma. Postoperative pathological and immunohistochemical examinations are crucial, and surgical resection of the lesion and local radiotherapy are effective treatment methods.

More Space, Less Noise-New-generation Low-Field Magnetic Resonance Imaging Systems Can Improve Patient Comfort: A Prospective 0.55T-1.5T-Scanner Comparison.

The objectives of this study were to assess patient comfort when imaged on a newly introduced 0.55T low-field magnetic resonance (MR) scanner system with a wider bore opening compared to a conventional 1.5T MR scanner system. In this prospective study, fifty patients (mean age: 66.2 ± 17.0 years, 22 females, 28 males) underwent subsequent magnetic resonance imaging (MRI) examinations with matched imaging protocols at 0.55T (MAGNETOM FreeMax, Siemens Healthineers; Erlangen, Germany) and 1.5T (MAGNETOM Avanto Fit, Siemens Healthineers; Erlangen, Germany) on the same day. MRI performed between 05/2021 and 07/2021 was included for analysis. The 0.55T MRI system had a bore opening of 80 cm, while the bore diameter of the 1.5T scanner system was 60 cm. Four patient groups were defined by imaged body regions: (1) cranial or cervical spine MRI using a head/neck coil (n = 27), (2) lumbar or thoracic spine MRI using only the in-table spine coils (n = 10), (3) hip MRI using a large flex coil (n = 8) and (4) upper- or lower-extremity MRI using small flex coils (n = 5). Following the MRI examinations, patients evaluated (1) sense of space, (2) noise level, (3) comfort, (4) coil comfort and (5) overall examination impression on a 5-point Likert-scale (range: 1= "much worse" to 5 = "much better") using a questionnaire. Maximum noise levels of all performed imaging studies were measured in decibels (dB) by a sound level meter placed in the bore center. Sense of space was perceived to be "better" or "much better" by 84% of patients for imaging examinations performed on the 0.55T MRI scanner system (mean score: 4.34 ± 0.75). Additionally, 84% of patients rated noise levels as "better" or "much better" when imaged on the low-field scanner system (mean score: 3.90 ± 0.61). Overall sensation during the imaging examination at 0.55T was rated as "better" or "much better" by 78% of patients (mean score: 3.96 ± 0.70). Quantitative assessment showed significantly reduced maximum noise levels for all 0.55T MRI studies, regardless of body region compared to 1.5T, i.e., brain MRI (83.8 ± 3.6 dB vs. 89.3 ± 5.4 dB; p = 0.04), spine MRI (83.7 ± 3.7 dB vs. 89.4 ± 2.6 dB; p = 0.004) and hip MRI (86.3 ± 5.0 dB vs. 89.1 ± 1.4 dB; p = 0.04). Patients perceived 0.55T new-generation low-field MRI to be more comfortable than conventional 1.5T MRI, given its larger bore opening and reduced noise levels during image acquisition. Therefore, new concepts regarding bore design and noise level reduction of MR scanner systems may help to reduce patient anxiety and improve well-being when undergoing MR imaging.

Minimizing the Risk of Vascular Injury: Anatomy of the Popliteal Artery in the Pediatric Knee.

Displaced pediatric tibial tubercle fractures are commonly stabilized with screws directed posteriorly toward neurovascular structures. Here, we (1) characterize the variation of the popliteal artery among pediatric patients; and (2) recommend a safe screw trajectory for fixation of tibial tubercle fractures. We retrospectively identified 42 patients (42 knees; 29 female) aged 12-17 years with lower-extremity magnetic resonance imaging (MRI) at a tertiary academic center. The mean patient age was 14.5 (range: 12-17) years, and the mean body mass index value was 19.1 (range: 14.9-25.1). We included patients with open physes or visible physeal scars and excluded those with prior instrumentation or lower-extremity injury. Using sagittal MRI, we measured the distances from 5 levels each on the anterior and posterior tibial cortex to the popliteal artery (level 1, midpoint of proximal tibial epiphysis; level 2, the proximal extent of the tubercle; level 3, tubercle prominence; level 4, 2cm distal to the proximal extent of the tubercle; level 5, 4cm distal to the proximal extent of the tubercle). Using coronal MRI, we measured the width of the tibia at each level and the distance from the lateral-most and medial-most cortex to the artery. The popliteal artery was laterally positioned in all knees. The mean distance between the artery and lateral-most aspect of the tibia at each level ranged from 1.9 to 2.4cm, and from 2.3 to 3.9cm from the medial-most aspect of the tibia. The mean distance that a screw can advance before vascular injury was 5.1cm at level 1. The shortest mean distance to the popliteal artery was 1.7cm, at level 5. There is minimal distance between the posterior tibial cortex and the artery at all levels. Understanding the position of the popliteal artery in pediatric patients can help when stabilizing tibial tubercle fractures. Because the artery is close to the posterior cortex, a drill exiting in line with the popliteal artery risks vascular injury. Therefore, we recommend that screws exit within the medial 60% of the tibia. IV.

Post-COVID-19 vaccination inflammatory syndrome: A case report.

ABSTRACTA previously healthy 24-year-old male patient was referred to our clinic with bilateral lower extremity pain and dark urine, which developed two weeks after receiving the second dose of BNT162b2 vaccine against SARS-CoV-2. Laboratory tests indicated rhabdomyolysis. Lower extremity magnetic resonance imaging was compatible with myositis. Myositis-related antibodies were negative. Biopsy taken from gastrocnemius muscle revealed muscle necrosis and striking expression of major histocompatibility complex class I antigen. He was successfully treated, and his complaints resolved. One week later at follow-up, he reported new-onset exertional dyspnea with palpitations. ST-segment depressions were spotted on electrocardiography. Troponin T was found elevated as 0.595 ng/mL (normal <0.014 ng/mL). Echocardiography showed hypokinetic left ventricle with ejection fraction of 40%, and pericardial effusion of 2mm. An appropriate treatment plan was formulated for the diagnosis of myocarditis, eventually the patient recovered within ten days. BNT162b2 mRNA vaccine was felt to cause the aforementioned condition since no other etiology could be identified. Although it is known that BNT162b2 may induce myocarditis, myositis concomitant myocarditis appears to be a very rare adverse effect of this vaccine.

Clinical and Neuroimaging Features in Charcot-Marie-Tooth Patients with GNB4 Mutations.

Charcot–Marie–Tooth disease (CMT) is the most common inherited peripheral neuropathy. Mutations in the GNB4 gene cause dominant intermediate CMT type F (CMTDIF). The aim of this study is to investigate phenotypic heterogeneities and characteristics of CMT patients with GNB4 mutations. We enrolled 1143 Korean CMT families and excluded 344 families with a PMP22 duplication. We further analyzed the 799 remaining families to find their GNB4 mutations using whole-exome sequencing (WES). We identified two mutations (p.Gly77Arg and p.Lys89Glu) in three families, among which a heterozygous p.Gly77Arg mutation was novel. In addition, a significant uncertain variant (p.Thr177Asn) was observed in one family. The frequency of the GNB4 mutation in the Korean population is 0.38% in PMP22 duplication-negative families. All three families showed de novo mutation. Electrophysiological findings regarding the p.Lys89Glu mutation showed that the motor nerve conduction velocity (MNCV) of the median nerve was markedly reduced, indicating demyelinating neuropathy, and sural nerve biopsy revealed severe loss of myelinated axons with onion bulb formation. Lower extremity Magnetic Resonance Imaging (MRI) demonstrated relatively more severe intramuscular fat infiltrations in demyelinating type (p.Lys89Glu mutation) patients compared to intermediate type (p.Gly77Arg mutation) patients. The anterolateral and superficial posterior compartment muscles of the distal calf were preferentially affected in demyelinating type patients. Therefore, it seems that the investigated GNB4 mutations do cause not only the known intermediate type but also demyelinating-type neuropathy. We first presented three Korean families with GNB4 mutations and found phenotypic heterogeneities of both intermediate and demyelinating neuropathy. We suggest that those findings are useful for the differential diagnosis of CMT patients with unknown GNB4 variants.

Lower-extremity magnetic resonance imaging in patients with hyperkalemic periodic paralysis carrying the SCN4A mutation T704M: 30-month follow-up of seven patients

Hyperkalemic periodic paralysis (hyperKPP) is a muscle channelopathy characterized by recurrent paralytic attacks. Our previous study, in which we conducted whole-body muscle magnetic resonance imaging (MRI) in patients with hyperKPP, revealed muscle atrophy and fatty change in the lower extremity, especially in older persons. The aim of current study was to identify the progression of myopathy in hyperKPP patients had been assessed in the previous study. We performed lower-extremity muscle MRI in seven hyperKPP patients carrying the T704M mutation in the SCN4A gene at an interval of 30 months. Muscle atrophy, edematous change, fatty change, and fat fraction quantified using the Dixon technique were compared with the previous MRI findings. The lower-extremity MRI scan showed progressive muscle pathologic findings when compared with the previous study. Muscle atrophy, edematous change, and fatty change were prominent in the superficial posterior compartment of the lower leg. The follow-up lower-extremity muscle MRI findings provide evidence for chronic progressive myopathy and suggest the usefulness of MRI for assessing disease progression in patients with hyperKPP. This study is meaningful in terms of providing data showing the longitudinal changes of muscles in patients with periodic paralysis.

Anthropometric Measurements of Knee Joints in the Hispanic Population

BackgroundTotal knee arthroplasty (TKA) systems provide a set of incrementally sized tibial and femoral components intended to accommodate most knee parameters. However, the most commonly used systems in the United States were developed using data from Caucasian patients which might not lead to the best fit in non-Caucasians. Therefore, we wanted to evaluate whether these TKA systems proportionally match femoral and tibial measurements in Hispanics. MethodsAll lower extremity magnetic resonance imaging performed at our institution between January 2007 and October 2015 were screened. A total of 500 nonarthritic knees from the same number of Hispanic patients were included in this retrospective descriptive radiographic study. Intraoperative osseous TKA resections were simulated on magnetic resonance imaging. Linear regression analyses were used to contrast the mediolateral (ML) width/anteroposterior (AP) length of simulated resected femoral condyle and tibia with the ML/AP dimensions of components offered by 4 current TKA systems. ResultsSimulated resected male femurs tended to be wider than most TKA system components for a given AP size, probably leading to component ML underhang. Altogether, systems studied accommodated most AP and ML measurements of female condyles. However, we identified subsets of Hispanic female patients with certain AP lengths and/or ML widths that particular knee systems could not accommodate. Resected male and female tibias tended to be slightly narrower than all TKA systems for a given AP size. ConclusionThe results of our study provide valuable data concerning the unique morphology of the Hispanic knee. These data can assist surgeons in the selection of the most suitable TKA systems for these patients.

Administrative Algorithms to identify Avascular necrosis of bone among patients undergoing upper or lower extremity magnetic resonance imaging: a validation study

BackgroundStudies of the epidemiology and outcomes of avascular necrosis (AVN) require accurate case-finding methods. The aim of this study was to evaluate performance characteristics of a claims-based algorithm designed to identify AVN cases in administrative data.MethodsUsing a centralized patient registry from a US academic medical center, we identified all adults aged ≥18 years who underwent magnetic resonance imaging (MRI) of an upper/lower extremity joint during the 1.5 year study period. A radiologist report confirming AVN on MRI served as the gold standard. We examined the sensitivity, specificity, positive predictive value (PPV) and positive likelihood ratio (LR+) of four algorithms (A-D) using International Classification of Diseases, 9th edition (ICD-9) codes for AVN. The algorithms ranged from least stringent (Algorithm A, requiring ≥1 ICD-9 code for AVN [733.4X]) to most stringent (Algorithm D, requiring ≥3 ICD-9 codes, each at least 30 days apart).ResultsAmong 8200 patients who underwent MRI, 83 (1.0% [95% CI 0.78–1.22]) had AVN by gold standard. Algorithm A yielded the highest sensitivity (81.9%, 95% CI 72.0–89.5), with PPV of 66.0% (95% CI 56.0–75.1). The PPV of algorithm D increased to 82.2% (95% CI 67.9–92.0), although sensitivity decreased to 44.6% (95% CI 33.7–55.9). All four algorithms had specificities >99%.ConclusionAn algorithm that uses a single billing code to screen for AVN among those who had MRI has the highest sensitivity and is best suited for studies in which further medical record review confirming AVN is feasible. Algorithms using multiple billing codes are recommended for use in administrative databases when further AVN validation is not feasible.

The Pearls and Pitfalls of Magnetic Resonance Imaging of the Lower Extremity

This article is intended for the clinician charged with either diagnosing or treating patients with lower extremity symptoms thought to be of musculoskeletal etiology. It gives a brief overview of the imaging techniques that can be utilized, common pathology, and certain pearls and pitfalls that may be encountered in both ordering and interpreting lower extremity magnetic resonance imaging. While we cannot present a comprehensive discussion of all of the known disorders in the lower extremity, we will choose common disorders to illustrate the diagnostic benefits and limitations of magnetic resonance imaging and provide reasons for choosing certain magnetic resonance imaging techniques.

Tibial Neuropathy Associated with Behcet's Disease

A 39-yr-old female patient was admitted to the neurology department reporting a burning pain and a tingling sensation on the left sole, which was followed by weakness of the left toes for >2 wks. Two years previously, she had experienced similar symptoms on the right sole, which improved with conservative management. On admission, recurrent oral ulcers, genital ulcers, and a uveitis history were identified, which met the diagnostic criteria of Behcet's disease (BD).1 A neurologic examination showed slight weakness in flexion, extension, and abduction of the left toes (Medical Research Council grade IV), and a sensory examination revealed hypoesthesia on the left sole and on the anterior one third of the right sole. Deep tendon reflexes were normoactive, no pathologic reflexes were observed, and Tinel's sign was positive at the left medial malleolus. Nerve conduction studies revealed decreased amplitude of the compound motor action potentials and no F-waves in either tibial nerves. Needle electrode examination revealed positive sharp waves in muscles innervated by the left tibial nerve and large amplitude polyphasic motor unit potentials in bilateral tibial nerve innervated muscles. Ankle magnetic resonance imaging (MRI) 2 wks after symptom onset revealed diffuse swelling with heterogeneous enhancement in the left tibial nerve at the calf level and high signal intensities in the left flexor hallucis longus, flexor digitorum longus, and tibialis posterior muscles. (Figs. 1A, B) There was no evidence of a structural lesion compressing the tibial nerve. Lower extremity MRI at thigh level revealed no signal change in the sciatic nerve or surrounding muscles, and lumbar spine MRI showed no evidence of root compression. Her sensory symptoms improved significantly after administering intravenous steroid (1000 mg methylprednisolone) for 5 days.FIGURE 1: Sagittal fat-suppressed fast T2-weighted (A) and fat-suppressed gadolinium-enhanced T1-weighted spin-echo magnetic resonance images (B) show diffuse swelling and heterogeneous enhancement of the left tibial nerve (arrows) at the calf level.Although the central nervous system is frequently involved in BD, peripheral nervous system involvement has rarely been described.2,3 However, recent studies have revealed that subclinical involvement of the peripheral nervous system is not uncommon in BD, and, thus, associations between BD and peripheral nervous system dysfunction are to be expected.4 In our case, recurrent tibial neuropathy was suspected, and no other specific cause except BD for tibial neuropathy was found. Our case suggests that recurrent mononeuropathy is a possible presenting symptom of BD, and that BD should be considered in patients with idiopathic recurrent mononeuropathy.

A case of ANCA-associated vasculitis presenting with calf claudication

Wegener's granulomatosis (WG), Churg-Strauss syndrome, and microscopic polyangiitis (MPA) are closely related small vessel vasculitides characterized by anti-neutrophil cytoplasmic antibodies (ANCA). Although there were some reports of MPA presenting with claudication, there are very few reports on WG presenting with claudication of calf muscles. We report an unusual case of ANCA-associated vasculitis in a 75-year-old man who presented with bilateral calf claudication. Comprehensive evaluations, including electromyography, nerve conduction study, lower extremity magnetic resonance imaging, and Doppler scan, did not reveal any other cause of bilateral calf claudication. P-ANCA and anti-myeloperoxidase antibody was positive, but the anti-proteinase 3 antibody was negative. Chest computed tomography scan showed subpleural honeycombing and reticulation, predominantly in both basal lung areas. Biopsy of the calf muscle showed granulomatous vasculitis. Kidney biopsy was also performed which revealed focal necrotizing glomerulonephritis. Our patient does not exhibit typical clinical features for WG, but histopathologic findings of necrotizing granulomatous vasculitis in calf muscle biopsy is highly suggestive of WG.

Juxta-articular Myxoma Within the Suprapatellar Pouch Masquerading as a Ganglion Cyst

This article presents the case of a 63-year-old man who noted painless swelling within the suprapatellar pouch, which he attributed to an effusion. Small-magnet, lower-extremity magnetic resonance imaging (MRI) and subsequent arthroscopy missed the lesion. On MRI with gadolinium contrast, the lesion was defined but misdiagnosed as a suprapatellar pouch ganglion cyst. Following resection of the 6 x 5 x 1.8-cm lesion, histology confirmed a lobular benign tumor with cystic elements recognized in the pathology and radiology literature as juxta-articular myxoma. Such lesions are characteristically multilobulated and contained within a capsular rim that enhances with gadolinium venous contrast. Otherwise, they appear hyperintense to fat on T2-weighted images and hypointense to muscle on T1-weighted images. This is an uncommonly encountered but known cystic lesion around the knee that is most often confused with ganglion cyst, synovial lipoma, lipoma arborescens, or pigmented or non-pigmented villonodular synovitis. Given its more cellular nature and thicker encapsulation, it should be able to be differentiated from ganglion cyst on MRI with a high index of suspicion, and should be recognized because of its high rate of recurrence. Unusual in this case was its location within the suprapatellar pouch, demonstrating the ease with which such lesions can be missed arthroscopically despite significant mass.

Trends in utilization: has extremity MR imaging replaced diagnostic arthroscopy?

To examine the relative change in utilization of magnetic resonance (MR) imaging of the extremities versus diagnostic and therapeutic arthroscopy. Using the 1993, 1996, and 1999 nationwide Medicare Part B databases, utilization rates (per 100000) were determined for upper and lower extremity MR imaging, diagnostic arthroscopy and therapeutic arthroscopy using CPT-4 codes. Utilization of extremity MR imaging was compared with that of diagnostic and therapeutic arthroscopy in 10 geographic regions of the United States and tracked over time. Combined lower and upper extremity MR imaging utilization per 100000 increased from 393 to 1056 in 1999 (+168.7%). Utilization of diagnostic arthroscopy of the extremities decreased from 18 in 1993 to 8 in 1999 (-55.6%); therapeutic arthroscopy rates increased from 461 in 1993 to 636 in 1999 (+40.0%). Specifically, from 1993 to 1999, utilization of lower extremity MR imaging increased from 270 to 661 (+144.8%). Utilization of diagnostic arthroscopy of the knee over the same time period decreased from 11 to 5 (-54.5%); therapeutic arthroscopy increased from 394 to 501 (+27.2%). Similarly, utilization rates for upper extremity MR imaging increased from 123 to 395 (+221.1%). Utilization of diagnostic arthroscopy of the shoulder over the same time period decreased from 7 to 2 (-71.4%); therapeutic arthroscopy increased from 44 to 104 (+136.4%). No specific geographic trends were ascertained. The utilization of MR imaging of the extremities has markedly increased from 1993 to 1999. During the same time period the utilization of diagnostic arthroscopy has decreased and that of therapeutic arthroscopy has increased. These findings support the hypothesis that there is increased reliance of clinical practitioners on the diagnostic information provided by MR imaging in preoperative clinical decision-making.