Intraarticular Steroid Injection in Hip and Knee with Fluoroscopic Guidance: Reassessing Safety.

Background Intraarticular corticosteroid (IACS) injections are frequently performed for hip and knee osteoarthritis (OA); however, there are conflicting data about the benefits and complications of IACS injections and a lack of large studies with follow-up. Purpose To determine the number of patients with complications after hip and knee IACS injections in a large study sample with long-term follow-up. Materials and Methods This retrospective single-center case series included patients who received a corticosteroid injection in the hip (n = 500) or knee (n = 500) and who underwent clinical and radiologic follow-up (conventional radiography, fluoroscopy, CT, or MRI) between 1 and 12 months after injection (January 2016 to May 2020). General descriptive statistics and the χ2 test were applied. P < .05 was indicative of a significant difference. Results Of the 1000 patients (mean age, 57 years ± 16 [SD]; 545 women), 10 patients (1%) developed severe complications. Four patients developed osteonecrosis; three, insufficiency fractures; and three, rapid progressive OA. All 10 complications occurred between 2 and 9 months after injection: six (60%) in the hip and four (40%) in the knee. Of the included 1000 patients, 545 (54%) were women, but they had nine of the 10 (90%) complications (P = .02). Conclusion Intraarticular steroid injection had a substantially lower complication rate than that reported in previous smaller studies. The rate of severe complications was disproportionally higher in women than in men. © RSNA, 2022 See also the editorial by Jennings in this issue.

CT-guided transforaminal epidural steroid injection for discogenic lumbar radiculopathy: influence of contrast dispersion and radiologist's experience on clinical outcome.

OBJECTIVE: To investigate the impact of contrast dispersion pattern/location during lumbar CT-guided transforaminal epidural steroid injection (TFESI) and experience of the performing radiologist on therapeutic outcome. MATERIALS AND METHODS: In this single-center retrospective cohort study, two observers analyzed contrast dispersion during CT-guided TFESI of 204 patients (age 61.1 ± 14 years) with discogenic unilateral single-level L4 or L5 radiculopathy. The contrast dispersion pattern was classified as "focal," "linear," or "tram-track"; the location was divided into "extraforaminal," "foraminal," or "recessal." Pain was assessed before and 4 weeks after treatment using a numerical rating scale (0, no pain; 10, intolerable pain). Additionally, the patient global impression of change (PGIC) was assessed. The TFESI was performed by musculoskeletal radiologists (experience range: first year of musculoskeletal fellowship training to 19 years). Contrast pattern/location and radiologist's experience were compared between "good responder" (≥ 50% pain reduction) and "poor responder" (< 50%). A p-value < 0.05 was considered to be statistically significant. RESULTS: Overall, CT-guided TFESI resulted in a substantial pain reduction in 46.6% of patients with discogenic radiculopathy. The contrast dispersion pattern and location had no effect on pain relief (p = 0.75 and p = 0.09) and PGIC (p = 0.70 and p = 0.21) 4 weeks after TFESI. Additionally, the experience of the radiologist had no influence on pain reduction (p = 0.92) or PGIC (p = 0.75). Regarding pre-interventional imaging findings, both the location and grading of nerve compression had no effect on pain relief (p = 0.91 and p = 0.85) and PGIC (p = 0.18 and p = 0.31). CONCLUSION: Our results indicate that neither contrast agent dispersion/location nor the experience of the radiologist allows predicting the therapeutic outcome 4 weeks after the procedure.

Ligaments of the scapho-trapezial-trapezoidal joint: MR anatomy in asymptomatic and symptomatic individuals.

PURPOSE: To evaluate the MRI anatomy of the scapho-trapezial-trapezoidal (STT) ligament complex in asymptomatic and symptomatic individuals. MATERIAL AND METHODS: In this retrospective study, STT ligament complex of 42 (male 69%, median age 37.5 years) asymptomatic (n = 25) and symptomatic (n = 17) (defined as pain described over the STT joint) individuals was examined using a high-resolution 3D proton density-weighted isovoxel sequence (MR arthrogram) with multiplanar reconstructions. Two musculoskeletal radiologists independently assessed visibility, signal intensity (SI), morphology, and thickness of the radiopalmar scapho-trapezial ligament (rpSTL), palmar scapho-capitate capsular ligament (pSCL), palmar STT capsule (pSTTC), and dorsal STT capsule (dSTTC). RESULTS: Interreader agreement ranged from fair to good and intraclass correlations were good. The rpSTL was almost always visible (85.7%/80.1%; reader 1/reader 2). The pSCL and dSTTC were visible in all cases. The pSTTC was visible in only 52.4%/42.9%. Mean thickness of the rpSTL, pSCL, pSTTC, and dSTTC was 1.4 ± 0.5 mm/1.3 ± 0.5 mm, 2.8 ± 0.7 mm/2.7 ± 0.6 mm, 0.5 ± 0.5 mm/0.4 ± 0.4 mm, and 0.5 ± 0.3 mm/0.3 ± 0.3 mm. Both readers rated SI of the rpSTL significantly more often as increased in the symptomatic group (increased SI in asymptomatic group: 20%/15%; symptomatic group: 56%/50%) (p-values < 0.005). For all other ligaments, no significant difference was observed for SI between symptomatic and asymptomatic group (p-values ranging between 0.188 and 0.890). For all other ligaments, no significant differences were observed regarding ligament visibility, morphology, and thickness (p-values ranging between 0.274 and 1.000). CONCLUSION: The anatomy of the STT ligament complex can consistently be visualized on high-resolution 3D MRI. Increased signal intensity of rpSTL is significantly more frequent in patients with radial-sided wrist pain.

Virtual non-contrast images calculated from dual-energy CT shoulder arthrography improve the detection of intraarticular loose bodies.

OBJECTIVE: This study aims to evaluate the image quality of virtual non-contrast (VNC) images calculated from dual-energy CT shoulder arthrography (DECT-A) and their ability to detect periosteal calcifications and intraarticular loose bodies. MATERIALS AND METHODS: In 129 shoulders of 123 patients, DECT arthrography (80 kV/140 kV) was performed with diluted iodinated contrast material (80 mg/ml). VNC images were calculated with image postprocessing. VNC image quality (1 = worst, 5 = best), dose parameters, and CT numbers (intraarticular iodine, muscle, VNC joint fluid density) were assessed. Image contrast (iodine/muscle) and percentage of iodine removal were calculated. Two independent readers evaluated VNC and DECT-A images for periosteal calcifications and intraarticular loose bodies, and diagnostic confidence (1 = low, 4 = very high) was assessed. RESULTS: VNC images (129/129) were of good quality (median 4 (3-4)), and the mean effective dose of DECT-A scans was 2.21 mSv (± 1.0 mSv). CT numbers of iodine, muscle, and VNC joint fluid density were mean 1017.6 HU (± 251.6 HU), 64.6 HU (± 8.2 HU), and 85.3 HU (± 39.5 HU), respectively. Image contrast was mean 953.1 HU (± 251 HU) on DECT-A and 31.3 HU (± 32.3 HU) on VNC images. Iodine removal on VNC images was 91% on average. No difference was observed in the detection of periosteal calcifications between VNC (n = 25) and DECT-A images (n = 21) (p = 0.29), while the detection of intraarticular loose bodies was superior on VNC images (14 vs. 7; p = 0.02). Diagnostic confidence was higher on VNC images for both periosteal calcifications (median 3 (3-3) vs. 3 (3-3); p = 0.009) and intraarticular loose bodies (median 3 (3-4) vs. 3 (3-3); p < 0.001). CONCLUSION: VNC images from DECT shoulder arthrography are superior to DECT-A images for the detection of intraarticular loose bodies and increase the confidence in detecting periosteal calcifications.

The effect of native knee rotation on the tibial-tubercle-trochlear-groove distance in patients with patellar instability: an analysis of MRI and CT measurements.

BACKGROUND: This study aimed to quantify the effect of lower limb rotational parameters on the difference in the tibial-tubercle-trochlear-groove (TTTG) distance when assessed with magnetic resonance imaging (MRI) and computed tomography (CT) in patients with patellar instability. It was hypothesized that an increased native knee rotation angle significantly contributes to an underestimation of TTTG by MRI. METHODS: Forty patients with patellar instability who had undergone standard radiographs, MRI and CT scans were included in this retrospective study. A musculoskeletal radiologist assessed all imaging for TTTG, femoral and tibial rotation, knee rotation and flexion angle, and trochlear dysplasia. ΔTTTG was defined as the TTTG measured on MRI subtracted from the TTTG measured on CT. Statistical analysis determined the effect of these parameters on the calculated difference between TTTG when measured on CT and MRI. RESULTS: Equal knee flexion in MRI and CT resulted in a ΔTTTG of 0.1 ± 0.3 mm compared to 4.0 ± 3.3 mm in patients with different knee flexion angles in both imaging acquisitions (p = 0.036). The knee rotation angle measured on CT (native knee rotation angle) was negatively correlated with ΔTTTG (r = - 0.365; p = 0.002), while neither tibial nor femoral rotation showed any associations with TTTG (n.s.). Trochlear dysplasia did not show any significant correlation with ΔTTTG, regardless of classification by Dejour or Lippacher (n.s.). Both the native knee rotation angle and the MRI knee flexion angle were independent predictors of ΔTTTG, yet with an opposing effect (knee rotation: 95% Confidence Interval [CI] for ß - 0.468 to - 0.154, p < 0.001; knee flexion 95% CI for ß 0.292 to 0.587, p < 0.001). Patients with a native knee rotation angle > 20° showed a ΔTTTG of - 5.8 ± 4.0 mm (MRI rather overestimates TTTG) compared to 0.9 ± 4.1 mm Δ TTTG (MRI rather underestimates TTTG) in patients with < 20° native knee rotation angle. CONCLUSION: The native knee rotation angle is an independent, inversely correlated predictor of ΔTTTG, thus opposing the effect of knee flexion during MRI acquisition. Consequently, these results suggest that not only knee flexion but also knee rotation should be appreciated when assessing TTTG during patellar instability diagnostic evaluation as it can potentially lead to a false estimation of the TTTG distance on MRI. LEVEL OF EVIDENCE: Level III.

Elbow Instability.

The stability of the elbow is based on a combination of primary (static) and secondary stabilizers (dynamic). In varus stress, the bony structures and the lateral ulnar collateral ligament (LUCL) are the primary stabilizers, and in valgus stress, the ulnar collateral ligament (UCL) is the primary stabilizer. The flexor and extensor tendons crossing the elbow joint act as secondary stabilizers. Elbow instability is commonly divided into acute traumatic and chronic instability. Instability of the elbow is a continuum, with complete dislocation as its most severe form.Posterolateral rotatory instability is the most common elbow instability and can be detected at imaging both in the acute as well as the chronic phase. Imaging of suspected elbow instability starts with radiographs. Depending on the type of injury suspected, it is followed by magnetic resonance imaging (MRI) or computed tomography evaluation for depiction of a range of soft tissue and osseous injures. The most common soft tissue injuries are tears of the LUCL and the radial collateral ligament; the most common osseous injuries are an osseous LUCL avulsion, a fracture of the coronoid process, and a radial head fracture.Valgus instability is the second most common instability and mostly detected in the chronic phase, with valgus extension overload the dominant pattern of injury. The anterior part of the UCL is insufficient in valgus extension overload due to repetitive medial tension seen in many overhead throwing sports, with UCL damage readily seen at MRI.

Prospective and longitudinal evolution of postoperative periprosthetic findings on metal artifact-reduced MR imaging in asymptomatic patients after uncemented total hip arthroplasty.

OBJECTIVE: To prospectively assess the evolution of postoperative MRI findings in asymptomatic patients after total hip arthroplasty (THA) over 24 months (mo). METHODS: This prospective cohort study included 9 asymptomatic patients (56.7 ± 15.0 years) after THA. Metal artifact-reduced 1.5-T MRI was performed at 3, 6, 12, and 24 mo after surgery. The femoral stem and acetabular cup were assessed by two readers for bone marrow edema (BME), periprosthetic bone resorption, and periosteal edema in addition to periarticular soft tissue edema and joint effusion. RESULTS: BME was common around the femoral stem in all Gruen zones after 3 mo (range: 50-100%) and 6 mo (range: 33-100%) and in the acetabulum in DeLee and Charnley zone II after 3 mo (100%) and 6 mo (33%). BME decreased substantially after 12 mo (range: 0-78%) and 24 mo (range: 0-50%), may however persist in particular in Gruen zones 1 + 7. Periosteal edema along the stem was common 3 mo postoperatively (range: 63-75%) and rare after 24 mo: 13% only in Gruen zones 2 and 5. Twelve months and 24 mo postoperatively, periprosthetic bone resorption was occasionally present around the femoral stem (range: 11-33% and 13-38%, respectively). Soft tissue edema occurred exclusively along the surgical access route after 3 mo (100%) and 6 mo (89%) and never at 12 mo or 24 mo (0%). CONCLUSION: Around the femoral stem, BME (33-100%) and periosteal edema (0-75%) are common until 6 mo after THA, decreasing substantially in the following period, may however persist up to 24 mo (BME: 0-50%; periosteal edema: 0-13%) in few non-adjoining Gruen zones. Soft tissue edema along the surgical access route should have disappeared 12 mo after surgery.

Titanium-Coated Polyetheretherketone Cages Vs Full Titanium Cages for Stand-Alone 1- or 2-Level Anterior Cervical Discectomy and Fusion: A Comparative Study.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) for the surgical treatment of cervical degenerative disease often includes an intervertebral cage, which restores disc height and lordosis while promoting fusion . Cage materials include titanium (TTN) or polyetheretherketone (PEEK). Controversy in material selection stems from higher fusion rates with TNN, despite a higher subsidence rate, while PEEK cages demonstrate superior preservation of interspace height. Combining the advantages of both materials, TTN-coated PEEK (TCPEEK) cages were developed, featuring a PEEK core with similar stiffness to the bone, enveloped with a TTN coat, improving osteointegration. However, the potential superiority of TCPEEK over TTN cages has not been investigated. This study aimed to compare clinical and radiographic outcomes following single- or double-level ACDF using either TTN or TCPEEK cages. METHODS: This retrospective single-center study included patients undergoing single- or double-level ACDF between 2017 and 2019. Clinical outcomes included the Neck Disability Index and revision surgery incidence. Radiographic parameters included cervical and segmental lordosis, C2 to C7 sagittal vertical axis, fusion, subsidence, and adjacent segment degeneration at a minimum 12-month follow-up. RESULTS: A total of 45 patients (16 TTN; 29 TCPEEK) and 58 cervical levels (21 TTN; 37 TCPEEK) were included. Both cages significantly improved Neck Disability Index scores (TTN -10.0; TCPEEK -14.1) without significant differences. Two single-level TCPEEK patients required revision surgery due to non-union. In the radiological assessments, no significant difference was found for subsidence rates (TTN 52.4%; TCPEEK 56.8%), adjacent segment degeneration, cervical and segmental lordosis, and changes in C2 to C7 sagittal vertical axis. Though not statistically significant, fusion rates trended slightly higher with TTN (90.5%) vs TCPEEK cages (86.5%). CONCLUSION: TTN and TCPEEK cages achieve satisfactory clinical and radiological outcomes in single- or double-level ACDF. This finding suggests that the choice between them can be based on other factors, such as surgeon preference or availability, rather than specific material properties. CLINICAL RELEVANCE: This study found that the selection of ACDF cage material did not affect clinical outcomes.

Reversible switching and stability of the epigenetic memory system in bacteria.

In previous work, we have developed a DNA methylation-based epigenetic memory system that operates in Escherichia coli to detect environmental signals, trigger a phenotypic switch of the cells and store the information in DNA methylation. The system is based on the CcrM DNA methyltransferase and a synthetic zinc finger (ZnF4), which binds DNA in a CcrM methylation-dependent manner and functions as a repressor for a ccrM gene expressed together with an egfp reporter gene. Here, we developed a reversible reset for this memory system by adding an increased concentration of ZnSO4 to the bacterial cultivation medium and demonstrate that one bacterial culture could be reversibly switched ON and OFF in several cycles. We show that a previously developed differential equation model of the memory system can also describe the new data. Then, we studied the long-term stability of the ON-state of the system over approximately 100 cell divisions showing a gradual loss of ON-state signal starting after 4 days of cultivation that is caused by individual cells switching from an ON- into the OFF-state. Over time, the methylation of the ZnF4-binding sites is not fully maintained leading to an increased OFF switching probability of cells, because stronger binding of ZnF4 to partially demethylated operator sites leads to further reductions in the cellular concentrations of CcrM. These data will support future design to further stabilize the ON-state and enforce the binary switching behaviour of the system. Together with the development of a reversible OFF switch, our new findings strongly increase the capabilities of bacterial epigenetic biosensors.

Model-Based Design of a Synthetic Oscillator Based on an Epigenetic Methylation Memory System.

Oscillations are an important component in biological systems; grasping their mechanisms and regulation, however, is difficult. Here, we use the theory of dynamical systems to support the design of oscillatory systems based on epigenetic control elements. Specifically, we use results that extend the Poincaré-Bendixson theorem for monotone control systems that are coupled to a negative feedback circuit. The methodology is applied to a synthetic epigenetic memory system based on DNA methylation that serves as a monotone control system, which is coupled to a negative feedback. This system is generally able to show sustained oscillations according to its structure; however, a first experimental implementation showed that fine-tuning of several parameters is required. We provide design support by exploring the experimental design space using systems-theoretic analysis of a computational model.

The influence of different patient positions on the preoperative 3D planning for surgical resection of soft tissue sarcoma in the lower limb-a cadaver pilot study.

INTRODUCTION: Complete surgical resection remains the mainstay of the treatment of soft tissue sarcomas. Intraoperative positioning of the patient is dictated by tumor location, whereas preoperative imaging is always performed in the supine position. The effect of changing the patient position on the exact location of the tumor with regard to neurovascular structures and bone is unknown. MATERIAL AND METHODS: Two fresh frozen cadavers (pelvis and legs) were thawed and warmed. Three standardized tumor models were implanted in the thigh and calf. MR/CT images of the cadavers were obtained sequentially in four different patient positions. The minimal distance of each "tumor" to neurovascular structures was measured on axial MR images and the 3D shift of the center of the tumor to the bone was measured after segmentation of the CT images. RESULTS: A significant difference of the minimal distance of the "tumor" to the femoral artery (P = 0.019/0.023) and a significantly greater number of deviations of more than 5mm/10 mm in the thigh between the supine position and the other positions compared to two supine positions (p = 0.027/0.028) were seen. The center of the "tumor" compared to the bone shifted significantly in the thigh (P < 0.001/0.002) but not the lower leg. CONCLUSION: Obtaining images in the same patient position as the planned tumor resection may become particularly relevant if computer assisted surgery, which is based on preoperative imaging, is introduced into soft tissue sarcoma surgery as the patient position significantly influences the spatial position of the tumor.