Mid-term results of autologous matrix-induced chondrogenesis for large chondral defects in hips with femoroacetabular impingement syndrome.

Aims: The purpose of this study was to evaluate the mid-term outcomes of autologous matrix-induced chondrogenesis (AMIC) for the treatment of larger cartilage lesions and deformity correction in hips suffering from symptomatic femoroacetabular impingement (FAI). Methods: This single-centre study focused on a cohort of 24 patients with cam- or pincer-type FAI, full-thickness femoral or acetabular chondral lesions, or osteochondral lesions ≥ 2 cm2, who underwent surgical hip dislocation for FAI correction in combination with AMIC between March 2009 and February 2016. Baseline data were retrospectively obtained from patient files. Mid-term outcomes were prospectively collected at a follow-up in 2020: cartilage repair tissue quality was evaluated by MRI using the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score. Patient-reported outcome measures (PROMs) included the Oxford Hip Score (OHS) and Core Outcome Measure Index (COMI). Clinical examination included range of motion, impingement tests, and pain. Results: A total of 12 hips from 11 patients were included (ten males, one female, mean age 26.8 years (SD 5.0), mean follow-up 6.2 years (SD 5.2 months)). The mean postoperative MOCART score was 66.3 (SD 16.3). None of the patients required conversion to total hip arthroplasty. Two patients had anterior impingement. External hip rotation was moderately limited in four patients. There was a correlation between MOCART and follow-up time (rs = -0.61; p = 0.035), but not with initial cartilage damage, age, BMI, or imaging time delay before surgery. PROMs improved significantly: OHS from 37.4 to 42.7 (p = 0.014) and COMI from 4.1 to 1.6 (p = 0.025). There was no correlation between MOCART and PROMs. Conclusion: Based on the reported mid-term results, we consider AMIC as an encouraging treatment option for large cartilage lesions of the hip. Nonetheless, the clinical evidence of AMIC in FAI patients remains to be determined, ideally in the context of randomized controlled trials.

Morphological and Quantitative Parametric MRI Follow-up of Cartilage Changes Before and After Intra-articular Injection Therapy in Patients With Mild to Moderate Knee Osteoarthritis: A Randomized, Placebo-Controlled Trial.

BACKGROUND: Intra-articular injections are routinely used for conservative treatment of knee osteoarthritis (OA). The detailed comparative therapeutic effects of these injections on cartilage tissue are still unclear. OBJECTIVE: The aim of this study was to detect and compare knee cartilage changes after intra-articular injection of glucocorticoid, hyaluronic acid, or platelet-rich plasma (PRP) to placebo using quantitative (T2 and T2* mapping) and morphological magnetic resonance imaging parameters in patients with mild or moderate osteoarthritis. MATERIALS AND METHODS: In a double-blinded, placebo-controlled, single-center trial, knees with mild or moderate osteoarthritis (Kellgren-Lawrence grade 1-3) were randomly assigned to an intra-articular injection with 1 of these substances: glucocorticoid, hyaluronic acid, PRP, or placebo. Cartilage degeneration on baseline and follow-up magnetic resonance imaging scans (after 3 and 12 months) was assessed by 2 readers using quantitative T2 and T2* times (milliseconds) and morphological parameters (modified Outerbridge grading, subchondral bone marrow edema, subchondral cysts, osteophytes). RESULTS: One hundred twenty knees (30 knees per treatment group) were analyzed with a median patient age of 60 years (interquartile range, 54.0-68.0 years). Interreader reliability was good for T2 (ICC, 0.76; IQR, 0.68-0.83) and T2* (ICC, 0.83; IQR, 0.76-0.88) measurements. Morphological parameters showed no significant changes between all groups after 3 and 12 months. T2 mapping after 12 months showed the following significant ( P = 0.001-0.03) changes between groups in 6 of 14 compartments: values after PRP injection decreased compared with glucocorticoid in 4 compartments (complete medial femoral condyle and central part of lateral condyle) and compared with placebo in 2 compartments (anterior and central part of medial tibial plateau); values after glucocorticoid injection decreased compared with placebo in 1 compartment (central part of medial tibial plateau). No significant changes were seen for T2 and T2* times after 3 months and T2* times after 12 months. No correlation was found between T2/T2* times and Kellgren-Lawrence grade, age, body mass index, or pain (Spearman ρ, -0.23 to 0.18). CONCLUSIONS: Platelet-rich plasma injection has a positive long-term effect on cartilage quality in the medial femoral compartment compared to glucocorticoid, resulting in significantly improved T2 values after 12 months. For morphological cartilage parameters, injections with glucocorticoid, PRP, or hyaluronic acid showed no better effect in the short or long term compared with placebo.

Value of MR arthrography for evaluation of children and adolescents with clinically suspected intraarticular cause of hip pain.

PURPOSE: To evaluate the distribution of intra- and extraarticular MRI findings in children and adolescents with clinically suspected intraarticular cause of hip pain in order to assess the need for additional intraarticular contrast administration. MATERIAL AND METHODS: Database was searched over a period of 34 months retrospectively for consecutive hip MR arthrography in young patients (8-17 years) with suspected intraarticular cause of hip or groin pain. Exclusion criteria were prior hip surgery, follow-up examination due to known intraarticular pathology, incomplete examination, qualitatively non-diagnostic examinations, and missing informed consent. Reports of fellowship-trained MSK radiologists were searched for intraarticular versus extraarticular findings explaining hip or groin pain. RESULTS: Seventy patients (68% female; median age: 14.5 years; range:10.8-16.9 years) were analyzed. No reason for pain was found in 30 (42.9%) hips, extraarticular reasons in 20 (28.6%) cases, intraarticular in 14 (20.0%), and both (intra- and extraarticular) in 6 (8.6%) hips. Most common extraarticular reasons were apophysitis (14.3%), other bony stress reactions (12.9%), intramuscular edema (7%), tendinitis (5.7%), and trochanteric bursitis (4.3%). Labral pathology was the most common intraarticular finding (overall:34.3%; partial tear:15.7%, complete tear:15.7%), most frequent at the anterosuperior position (81.8%). Cartilage defects (1.4%), intraarticular neoplasia (1.4%), and tear of the femoral head ligament (2.8%) were rarely found. Synovitis and loose bodies were not observed. Cam-(37.1%) and pincer-configurations (47.1%) were common while hip dysplasia was rare (5.7%). CONCLUSION: MRI in children and adolescents with hip pain should be done primarily without intraarticular contrast administration since most cases show an extraarticular pain reason or no diagnosis detectable with MRI.

Muscle atrophy in diabetic patients with Charcot foot: a case-control study.

PURPOSE: To evaluate the distribution and severity of muscle atrophy in diabetic patients with active Charcot foot (CF) compared to diabetic patients without CF. Furthermore, to correlate the muscle atrophy with severity of CF disease. MATERIAL/METHODS: In this retrospective study, MR images of 35 diabetic patients (21 male, median:62.1 years ± 9.9SD) with active CF were compared with an age- and gender-matched control group of diabetic patients without CF. Two readers evaluated fatty muscle infiltration (Goutallier-classification) in the mid- and hindfoot. Furthermore, muscle trophic (cross-sectional muscle area (CSA)), intramuscular edema (none/mild versus moderate/severe), and the severity of CF disease (Balgrist Score) were assessed. RESULTS: Interreader correlation for fatty infiltration was substantial to almost perfect (kappa-values:0.73-1.0). Frequency of fatty muscle infiltration was high in both groups (CF:97.1-100%; control:77.1-91.4%), but severe infiltration was significantly more frequent in CF patients (p-values: < 0.001-0.043). Muscle edema was also frequently seen in both groups, but significantly more often in the CF group (p-values: < 0.001-0.003). CSAs of hindfoot muscles were significantly smaller in the CF group. For the flexor digitorum brevis muscle, a cutoff value of 139 mm2 (sensitivity:62.9%; specificity:82.9%) in the hindfoot was found to differentiate between CF disease and the control group. No correlation was seen between fatty muscle infiltration and the Balgrist Score. CONCLUSION: Muscle atrophy and muscle edema are significantly more severe in diabetic patients with CF disease. Muscle atrophy does not correlate with the severity of active CF disease. A CSA < 139 mm2 of the flexor digitorum brevis muscle in the hindfoot may indicate CF disease.

A Randomized Trial of Intra-articular Injection Therapy for Knee Osteoarthritis.

BACKGROUND: Intra-articular injections are widely used for conservative treatment of knee osteoarthritis (OA). However, rigorous data are lacking regarding the comparative therapeutic effectiveness of these injections. PURPOSE: The aim of this study was to compare clinical outcomes after intra-articular injections of glucocorticoid, hyaluronic acid, platelet-rich plasma (PRP), or placebo in patients with mild or moderate OA of the knee. MATERIALS AND METHODS: In a double-blinded, placebo-controlled, single-center trial, we randomly assigned knees with early- to middle-stage knee OA (Kellgren-Lawrence grade 1-3) to an intra-articular injection with one of these substances: glucocorticoid, hyaluronic acid, PRP, or placebo. Primary outcome was pain reduction within 6 months after the injection, assessed with the numeric rating scale (NRS; range, 0-100). Secondary outcome parameters included WOMAC scores, Tegner Activity Scale, knee mobility, and adverse events. Finally, a linear mixed-effects model was calculated and corrected for possible patient and covariate effects. RESULTS: One hundred twenty knees (30 knees per treatment group) in 95 patients (41 female) were included in the final analysis. The median age of patients was 60 years (interquartile range, 54.0-68.0). There was no evidence that the drug effects of primary and secondary outcome parameters differed over time. The median pain at baseline was 32.5 (interquartile range, 15.00-50.00) on NRS. The changes in pain level during the first 6 months compared with baseline were small (within ±5 points on NRS), whereas the intrapatient variability was large between -20 and +20 points. Secondary outcome parameters did not differ significantly among the groups. Kellgren-Lawrence grade did not have a statistically significant effect on pain reduction ( P = 0.61). CONCLUSIONS: There is no evidence that knee injections with glucocorticoid, PRP, or hyaluronic acid have superior short- or long-term effects in patients with low pain level at baseline and early- to middle-stage knee OA when compared with placebo.

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.

The Vulcan salute sign: a non-sensitive but specific sign for Morton's neuroma on radiographs.

OBJECTIVES: To assess the value of the divergence of toes on conventional radiographs of the foot for diagnosing Morton's neuroma. METHODS: This retrospective case-control study was approved by the local ethics committee. In 100 patients with MRI-proven Morton's neuroma 2/3 or 3/4 (study group) and 100 patients without (control group), conventional weight-bearing dorso-plantar view radiographs were evaluated for the subjective presence of interphalangeal divergence, called the Vulcan salute sign or V-sign, by two blinded, independent musculoskeletal radiologists. Interphalangeal angles (2/3 and 3/4) and intermetatarsal angle I/V were measured. The t test and chi-squared test were used to compare the groups. Diagnostic performance was calculated. Interobserver reliability was assessed using κ statistics and intraclass correlation coefficient (ICC). RESULTS: The difference between the groups was significant (P < 0.05) regarding the presence of the V-sign, which was found in 30 of 100 patients with Morton neuroma and in 3 of 100 control patients, with a sensitivity of 30% and a specificity of 97%. The differences between interphalangeal angles were significant (P < 0.05) between the groups. The interphalangeal angle 2/3 mean values were 7.9° (± 4.8) for the study group vs 5.4° (± 2.6) for the controls; the 3/4 angle values were 6.5° (± 3.8) and 3.4° (± 2.5), respectively. There was no significant difference between the groups in the intermetatarsal angle I/V. Interobserver agreement was substantial for the V-sign, with a κ value of 0.78. The ICC was excellent concerning angle measurements, with all values ≥ 0.94. CONCLUSION: The Vulcan salute sign on conventional radiographs is specific for Morton's neuroma.

Ultra-high resolution 3D MRI for chondrocalcinosis detection in the knee-a prospective diagnostic accuracy study comparing 7-tesla and 3-tesla MRI with CT.

OBJECTIVES: To test the diagnostic accuracy of a 3D dual-echo steady-state (DESS) sequence at 7-T MRI regarding the detection of chondral calcific deposits of the knee in comparison to 3-T MRI, using CT as cross-sectional imaging reference standard. METHODS: CT and 7-T MRI (DESS) of knee joints in 42 patients with radiographically known chondrocalcinosis (13 of 42 bilateral) were prospectively acquired for all included patients (n = 55 knee joints). Additionally, 3-T MRI (DESS) was performed for 20 of these 55 knee joints. Two fellowship-trained musculoskeletal radiologists scored eight cartilage regions of each knee joint separately regarding presence of cartilage calcification, diagnostic confidence level, and sharpness of calcific deposits. In an explorative subanalysis, micro-CT of the menisci was evaluated after knee arthroplasty in one patient. Diagnostic performance metrics and nonparametric tests were used to compare between modalities. p values < 0.05 were considered to represent statistical significance. RESULTS: Sensitivity for chondrocalcinosis detection was significantly higher for 7-T MRI (100%) compared to 3-T MRI (reader 1: 95.9%, p = 0.03; reader 2: 93.2%, p = 0.002). The diagnostic confidence was significantly higher for both readers at 7 T compared to both 3-T MRI (p < 0.001) and to CT (p = 0.03). The delineation of chondral calcifications was significantly sharper for 7-T compared to both 3-T MRI and CT (p < 0.001, both readers). Micro-CT in one patient suggested that 7-T MRI may potentially outperform standard CT in diagnosing chondral calcifications. CONCLUSION: 3D-DESS imaging at 7-T MRI offers a significantly higher sensitivity in detection of chondral calcific deposits compared to 3-T MRI. KEY POINTS: • 3D dual-echo steady-state (DESS) MRI at 7 T has a higher sensitivity in detection of chondral calcific deposits compared to 3-T MRI (p ≤ 0.03). • 3D DESS MRI at 7 T yields no false-negative cases regarding presence of chondral calcific deposits. • 3D DESS MRI at 7 T offers better delineation and higher diagnostic confidence in detection of chondral calcific deposits compared to 3-T MRI (p < 0.001).

Pelvic bone CT: can tin-filtered ultra-low-dose CT and virtual radiographs be used as alternative for standard CT and digital radiographs?

OBJECTIVES: To compare ultra-low-dose CT (ULD-CT) of the osseous pelvis with tin filtration to standard clinical CT (CT), and to assess the quality of computed virtual pelvic radiographs (VRs). METHODS: CT protocols were optimized in a phantom and three pelvic cadavers. Thirty prospectively included patients received both standard CT (automated tube voltage selection and current modulation) and tin-filtered ULD-CT of the pelvis (Sn140kV/50mAs). VRs of ULD-CT data were computed using an adapted cone beam-based projection algorithm and were compared to digital radiographs (DRs) of the pelvis. CT and DR dose parameters and quantitative and qualitative measures (1 = worst, 4 = best) were compared. CT and ULD-CT were assessed for osseous pathologies. RESULTS: Dose reduction of ULD-CT was 84% compared to CT, with a median effective dose of 0.38 mSv (quartile 1-3: 0.37-0.4 mSv) versus 2.31 mSv (1.82-3.58 mSv; p < .001), respectively. Mean dose of DR was 0.37 mSv (± 0.14 mSv). The median signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of bone were significantly higher for CT (64.3 and 21.5, respectively) compared to ULD-CT (50.4 and 18.8; p ≤ .01), while ULD-CT was significantly more dose efficient (figure of merit (FOM) 927.6) than CT (FOM 167.6; p < .001). Both CT and ULD-CT were of good image quality with excellent depiction of anatomy, with a median score of 4 (4-4) for both methods (p = .1). Agreement was perfect between both methods regarding the prevalence of assessed osseous pathologies (p > .99). VRs were successfully calculated and were equivalent to DRs. CONCLUSION: Tin-filtered ULD-CT of the pelvis at a dose equivalent to standard radiographs is adequate for assessing bone anatomy and osseous pathologies and had a markedly superior dose efficiency than standard CT. KEY POINTS: • Ultra-low-dose pelvic CT with tin filtration (0.38 mSv) can be performed at a dose of digital radiographs (0.37 mSv), with a dose reduction of 84% compared to standard CT (2.31 mSv). • Tin-filtered ultra-low-dose CT had lower SNR and CNR and higher image noise than standard CT, but showed clear depiction of anatomy and accurate detection of osseous pathologies. • Virtual pelvic radiographs were successfully calculated from ultra-low-dose CT data and were equivalent to digital radiographs.

Osseous defect of the anteroinferior femoral head: is it associated with femoroacetabular impingement (FAI)?

OBJECTIVE: To evaluate the prevalence, morphology, and clinical significance of a repeatedly observed yet not examined circumscript osseous defect at the anteroinferior aspect of the femoral head, termed femoral head defect. MATERIALS AND METHODS: Retrospective study with approval of the institutional review board. There was informed consent by all individuals. Magnetic resonance imaging (MRI) hip examinations of 970 individuals (age 15 to 55) were analyzed for femoral head defect. Patients with femoral head defect were matched for age and gender with patients without defect. Two readers independently assessed MRI images regarding presence, location, and morphology of the defect. MR images and radiographs were analyzed for findings of femoroacetabular impingement (FAI). Femoral torsion was measured. Independent t test and chi-square test were used for statistics. RESULTS: Sixty-eight (7%) of 970 MRI examinations exhibited a femoral head defect in an anteroinferior location of the femoral head (29/400 men, 7.3%; 39/570 women, 6.8%; p = 0.8). The most frequent morphology of femoral head defect was type I, dent-like (34; 50%), followed by type II, crater-like (27; 40%), and III, cystic (7; 10%). Femoral head defect was slightly more common on the right hip (39 individuals; 57%) compared to left (29 individuals; 43%), non-significantly (p = 0.115). There was no association between FAI or its subtypes and the presence of femoral head defect (p = 0.890). Femoral antetorsion was reduced in patients with femoral head defect (12.9° ± 8.6) compared to patients without defect (15.2° ± 8.5), without statistical significance (p = 0.121). CONCLUSION: The femoral head defect is a common finding in MRI examinations of the hip and is situated in the anteroinferior location. There was no association with FAI yet a non-significant trend towards lower femoral antetorsion in patients with femoral head defects.

Influence of pregnancy/childbirth on long-term bone marrow edema and subchondral sclerosis of sacroiliac joints.

OBJECTIVE: To investigate long-term effects of pregnancy/childbirth on bone marrow edema (BME) and subchondral sclerosis of sacroiliac joints (SIJ) in comparison to MRI changes caused by spondyloarthritis (SpA) and assess the influence of birth method and number of children on SIJ-MRI changes. MATERIALS AND METHODS: This is a retrospective cohort study with 349 women (mean age 47 ± 14 years) suffering low back pain. Four subgroups were formed based on SpA diagnosis and childbirth (CB) history. Two musculoskeletal radiologists scored the presence of BME and sclerosis on SIJ-MRI using the Berlin method. Further, an 11-point "global assessment score" representing the overall confidence of SpA diagnosis based on MRI was evaluated in addition to the ASAS (Assessment of Spondyloarthritis International Society) criterion of "positive MRI" for sacroiliitis. RESULTS: CB did not correlate with BME score (p = 0.38), whereas SpA diagnosis was associated with a higher BME score (r = 0.31, p < 0.001). Both CB (r = 0.21, p < 0.001) and SpA diagnosis (r = 0.33, p < 0.001) were correlated with a higher sclerosis score. CB was not associated with a higher confidence level in diagnosing SpA based on MRI (p = 0.07), whereas SpA diagnosis was associated with a higher score (r = 0.61, p < 0.001). Both CB (phi = 0.13, p = 0.02) and SpA diagnosis (phi = 0.23, p < 0.001) were significantly associated with a positive ASAS criterion for sacroiliitis. In non-SpA patients with CB, number of children (p = 0.001) was an independent predictor of sclerosis score, while birth method yielded no significant effect (p = 0.75). CONCLUSION: Pregnancy/CB has no impact on long-term BME on SIJ, however, may cause long-term subchondral sclerosis-similar to SpA-associated sclerosis. Number of children is positively correlated with SIJ sclerosis. Birth method yields no effect on SIJ sclerosis.

The "Balgrist Score" for evaluation of Charcot foot: a predictive value for duration of off-loading treatment.

OBJECTIVE: To develop a new magnetic resonance imaging(MRI) scoring system for evaluation of active Charcot foot and to correlate the score with a duration of off-loading treatment ≥ 90 days. METHODS: An outpatient clinic database was searched retrospectively for MRIs of patients with active Charcot foot who completed off-loading treatment. Images were assessed by two radiologists (readers 1 and 2) and an orthopedic surgeon (reader 3). Sanders/Frykberg regions I-V were evaluated for soft tissue edema, bone marrow edema, erosions, subchondral cysts, joint destruction, fractures, and overall regional manifestation using a score according to degree of severity (0-3 points). Intraclass correlations (ICC) for interreader agreement and receiver operating characteristic analysis between MR findings and duration of off-loading-treatment were calculated. RESULTS: Sixty-five feet in 56 patients (34 men) with a mean age of 62.4 years (range: 44.5-85.5) were included. Region III (reader 1/reader 2: 93.6/90.8%) and region II (92.3/90.8%) were most affected. The most common findings in all regions were soft tissue edema and bone marrow edema. Mean time between MRI and cessation of off-loading-treatment was 150 days (range: 21-405). The Balgrist Score was defined in regions II and III using soft tissue edema, bone marrow edema, joint destruction, and fracture. Interreader agreement for Balgrist Score was excellent: readers 1/2: ICC 0.968 (95% CI: 0.948, 0.980); readers 1/2/3: ICC 0.856 (0.742, 0.917). A cutoff of ≥ 9.0 points in Balgrist Score (specificity 72%, sensitivity 66%) indicated a duration of off-loading treatment ≥ 90 days. CONCLUSION: The Balgrist Score is a new MR scoring system for assessment of active Charcot foot with excellent interreader agreement. The Balgrist Score can help to identify patients with off-loading treatment ≥ 90 days.

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.

Impact of stem design and cementation on postoperative femoral antetorsion in 227 patients with total hip arthroplasty (THA).

OBJECTIVE: In total hip arthroplasty (THA), surgeons attempt to achieve a physiological antetorsion. However, postoperative antetorsion of the femoral stem is known to show large variabilities. The purpose of this study was to assess whether postoperative antetorsion is influenced by stem design or cementation. MATERIALS AND METHODS: This retrospective study included 227 patients with a hip prosthesis with five different stem designs (S1: short curved, S2 and S3: standard straight, S4: standard straight collared, S5: cemented straight), who had metal suppressed 1.5T-MRI of the hip between February 2015 and October 2019. Measurement of femoral antetorsion was done independently by two fellowship-trained radiologists on axial images by measuring the angle between the long axis of the femoral neck and the posterior condylar tangent of the knee. Measured angles in the different groups were compared using the t test for independent samples. RESULTS: The cementless collared stem S4 showed the highest antetorsion with 18.1° (± 10.5°; range -10°-45°), which was significantly higher than the antetorsion of the collarless S3 with 13.3° (± 8.4°; - 4°-29°) and the cemented S5 with 12.7° (± 7.7°; - 3°-27°) with p = 0.012 and p = 0.007, respectively. S1 and S2 showed an antetorsion of 14.8° (± 10.0°; 1°-37°) and 14.1° (± 12.2°; - 20°-41°). The torsional variability of the cementless stems (S1-4) was significantly higher compared with that of the cemented S5 with a combined standard deviation of 10.5° and 7.7° (p = 0.019). CONCLUSION: Prosthesis design impacts the postoperative femoral antetorsion, with the cementless collared stem showing the highest antetorsion. Cemented stems demonstrated significantly lower variability, suggesting the lowest rate of inadvertent malrotation.

Glossary of terms for musculoskeletal radiology.

Members of the International Skeletal Society compiled a glossary of terms for musculoskeletal radiology. The authors also represent national radiology or pathology societies in Asia, Australia, Europe, and the USA. We provide brief descriptions of musculoskeletal structures, disease processes, and syndromes and address their imaging features. Given the abundance of musculoskeletal disorders and derangements, we chose to omit most terms relating to neoplasm, spine, intervention, and pediatrics. Consensus agreement was obtained from 19 musculoskeletal radiology societies worldwide.

Correction to: Deep convolutional neural network-based detection of meniscus tears: comparison with radiologists and surgery as standard of reference.

The article "Deep convolutional neural network-based detection of meniscus tears: comparison with radiologists and surgery as standard of reference.

Diagnosis of Periprosthetic Hip Joint Infection Using MRI with Metal Artifact Reduction at 1.5 T.

Background MRI with metal artifact reduction has gained importance in assessment of pain with total hip arthroplasty (THA). However, its role in diagnosis of periprosthetic joint infection (PJI) has not been well defined. Purpose To evaluate findings of PJI after THA and to determine the diagnostic performance of 1.5-T MRI with metal artifact reduction. Materials and Methods Dedicated compressed sensing-based slice encoding for metal artifact correction 1.5-T MRI examinations (from January 2015 to April 2018) in patients with THA PJI (infection group) and noninfected THA (control group) were retrospectively evaluated by two musculoskeletal radiologists. Fisher exact test was used to compare the groups. Sensitivity, specificity, and accuracy were evaluated for each finding. Interobserver reliability was assessed with κ statistics. Results Forty patients (mean age, 69 years ± 11 [standard deviation]; 26 men) in the infection group and 100 patients (mean age, 67 years ± 11; 42 men) in the control group were evaluated. Periosteal reaction, capsule edema, and intramuscular edema differed between the two groups (P < .001 for each finding). Periosteal reaction was found in 31 of 40 patients with infection and 10 of 100 participants in the control group (sensitivity, 78%; specificity, 90%; accuracy, 86%); capsule edema was found in 33 of 40 (infection group) and five of 100 (control group) (sensitivity, 83%; specificity, 95%; accuracy, 91%); and intramuscular edema was found in 38 of 40 (infection group) and 14 of 100 (control group) (sensitivity, 95%; specificity, 86%; accuracy, 89%). Interobserver agreement was almost perfect, with κ values between 0.88 and 0.92. No difference between the two groups was found regarding the presence of osteolysis (infection group, 23 of 40; control group, 60 of 100), bone marrow edema (39 of 40 vs 87 of 100), effusion (20 of 40 vs 26 of 100), abductor tendon lesion (22 of 40 vs 62 of 100), or bursitis (14 of 40 vs 34 of 100) (P > .05 for each finding). Conclusion The presence of periosteal reaction, capsule edema, and intramuscular edema after total hip arthroplasty at 1.5-T MRI with metal artifact reduction had a high accuracy in evaluation of periprosthetic joint infection. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Zanetti in this issue.

3D-printed anatomic models of the knee for evaluation of patellofemoral dysplasia in comparison to standard radiographs and computed tomography.

PURPOSE: To evaluate 3D-printed anatomic models of the distal femur and patella for diagnosis and classification of patellofemoral dysplasia in comparison to conventional radiographs (CR) and CT. METHOD: Following local ethics committee approval, CT-datasets of 50 patients were segmented and 3D-anatomic models of the distal femur and patella were printed. An expert panel reviewed CR, CT, 3D-models and patient history and classified the femoral trochleas into normal or Dejour type A-D and the patellas into Wiberg type A-C, which served as the standard of reference. The same classifications were performed by two readers independently, first based on 3D-models and after 3 weeks based on CR and CT. Descriptive statistics, ROC-analysis and inter-reader reliability were performed. RESULTS: Trochlear dysplasia was present in 28/50 patients. Evaluations of 3D-models vs. CR/CT for trochlear dysplasia showed a sensitivity/specificity of 89.3 %/100 % vs. 96.4 %/68.2 % for reader 1 and 96.4 %/100 % vs. 96.4 %/90.9 % for reader 2, and an area under the curve of 0.946 vs. 0.823 for reader 1 (p = 0.029) and 0.982 vs. 0.937 for reader 2 (p = 0.147). Evaluations of 3D-models vs. CR/CT for the Dejour classification showed a sensitivity/specificity of 32.1 %/100 % vs. 57.1 %/68.2 % for reader 1 and 46.4 %/100 % vs. 50 %/90.9 % for reader 2 without significant differences. No significant differences existed for Wiberg-classification (50-66 % exact matches) or inter-reader reliabilities between 3D-models and CR/CT for all assessments (Kappa 0.428-0.92). CONCLUSION: In comparison to radiographs and CT, 3D-models achieve similar diagnostic accuracy for detection of patellofemoral dysplasia and have the potential to improve diagnosis for less experienced physicians.

Deep Convolutional Neural Network-Based Diagnosis of Anterior Cruciate Ligament Tears: Performance Comparison of Homogenous Versus Heterogeneous Knee MRI Cohorts With Different Pulse Sequence Protocols and 1.5-T and 3-T Magnetic Field Strengths.

OBJECTIVES: The aim of this study was to clinically validate a Deep Convolutional Neural Network (DCNN) for the detection of surgically proven anterior cruciate ligament (ACL) tears in a large patient cohort and to analyze the effect of magnetic resonance examinations from different institutions, varying protocols, and field strengths. MATERIALS AND METHODS: After ethics committee approval, this retrospective analysis of prospectively collected data was performed on 512 consecutive subjects, who underwent knee magnetic resonance imaging (MRI) in a total of 59 different institutions followed by arthroscopic knee surgery at our institution. The DCNN and 3 fellowship-trained full-time academic musculoskeletal radiologists evaluated the MRI examinations for full-thickness ACL tears independently. Surgical reports served as the reference standard. Statistics included diagnostic performance metrics, including sensitivity, specificity, area under the receiver operating curve ("AUC ROC"), and kappa statistics. P values less than 0.05 were considered to represent statistical significance. RESULTS: Anterior cruciate ligament tears were present in 45.7% (234/512) and absent in 54.3% (278/512) of the subjects. The DCNN had a sensitivity of 96.1%, which was not significantly different from the readers (97.5%-97.9%; all P ≥ 0.118), but significantly lower specificity of 93.1% (readers, 99.6%-100%; all P < 0.001) and "AUC ROC" of 0.935 (readers, 0.989-0.991; all P < 0.001) for the entire cohort. Subgroup analysis showed a significantly lower sensitivity, specificity, and "AUC ROC" of the DCNN for outside MRI (92.5%, 87.1%, and 0.898, respectively) than in-house MRI (99.0%, 94.4%, and 0.967, respectively) examinations (P = 0.026, P = 0.043, and P < 0.05, respectively). There were no significant differences in DCNN performance for 1.5-T and 3-T MRI examinations (all P ≥ 0.753, respectively). CONCLUSIONS: Deep Convolutional Neural Network performance of ACL tear diagnosis can approach performance levels similar to fellowship-trained full-time academic musculoskeletal radiologists at 1.5 T and 3 T; however, the performance may decrease with increasing MRI examination heterogeneity.