Quantitative Assessment of Acetabular Defects in Revision Hip Arthroplasty Based on 3D Modeling: The Area Increase Ratio (AIR) Method.

The most common classifications for acetabular bone defects are based on radiographic two-dimensional imaging, with low reliability and reproducibility. With the rise of modern processing techniques based on 3D modelling, methodologies for the volumetric quantification of acetabular bone loss are available. Our study aims to describe a new methodology for the quantitative assessment of acetabular defects based on 3D modelling, focused on surface analysis of the integrity of the main anatomical structures of the acetabulum represented by four corresponding sectors (posterior, superior, anterior, and medial). The defect entity is measured as the area increase ratio (AIR) detected in all the sectors analyzed on three planes of view (frontal, sagittal, and axial) compared to healthy hemipelvises. The analysis was performed on 3D models from the CT-scan of six exemplary specimens with a unilateral pathological hemipelvis. The AIR between the native and the pathological hemipelvis was calculated for each sector, for a total of 48 analyses (range, +0.93-+171.35%). An AIR of >50% were found in 22/48 (45.8%) sectors and affected mostly the posterior, medial, and superior sectors (20/22, 90.9%). Qualitative analysis showed consistency between the data and the morphological features of the defects. Further studies with larger samples are needed to validate the methodology and potentially develop a new classification scheme.

Dual-Energy CT Arthrography: Advanced Muscolo-Skelatal Applications in Clinical Practice.

This paper provides a comprehensive overview of the potential applications of dual-energy CT (DECT) in improving image quality and the diagnostic capabilities of CT arthrography (CTA) in clinical practice. The paper covers the use of virtual non-contrast (VNC) images, in which the injected contrast medium is subtracted from the articular cavity in order to better analyze 2D and 3D images of the bone. Moreover, virtual monoenergetic imaging (VMI) applications and their potential use for the reduction of metal artifacts and improving image contrast are reviewed. The role of virtual non-calcium (VNCa) in detecting bone marrow edema surrounding the imaged joint will be discussed. Furthermore, the role of iodine maps in enhancing the contrast between soft tissues, optimizing the visualization of contrast material, and distinguishing contrast material from calcifications is described. Finally, a case series including different joints is provided to underline the additional advantages of high-spatial-resolution dual-energy CT reconstructed images.

Current Practice of Italian Association of Revision Surgery Members in the Treatment of Unified Classification System Type B Periprosthetic Femoral Fracture Around Hip Arthroplasty: A Cross-Sectional Survey.

Introduction: Periprosthetic femoral fracture around hip arthroplasty are growing in the world, nevertheless management and treatment options for fractures "around the stem" are still debated due to lack of high-level studies. Materials and method: A 85-item survey were fill out by 40 Italian Orthopedic Surgeon member of SIOT (Società Italiana di Ortopedia e Traumatologia) and AIR (Associazione Italiana Riprotesizzazione) to assess their current opinion in the management of type B periprosthetic femoral fractures. Responses were summarized using proportions, and further stratified by practice type, case volume, surgeon age, and fellowship training. Results: Vancouver/UCS fracture classification showed a good interobserver agreement (k value = .76). ORIF were the treatment of choice for UCS type B1 fractures (100%), revision stem for B2 (85%) and B3 (100%). Locked plates were preferred to cable plate and cerclage without a plate for B1 fractures (50% vs 40% vs 10%); revision with modular stem was preferred to monoblock stem for B2 fractures (50% vs 35%) and B3 (75% vs 15%). Responders tended to postpone at 1-month weight-bearing in patients with B1 fractures. Regarding postoperative pharmacological treatment there was absolute lack of consensus. Discussion: The primary finding of our survey confirmed the preference of ORIF for B1 fractures and stem revision for B2 and B3 fractures. However, there is no definitive operative technique for all UCS B fractures. Surgeons tended to favor locked plating over cable plating, although only slightly. This general lack of consensus coincides with the inconclusive evidence that currently exists in the literature, which demonstrates both favorable and unfavorable outcomes for both techniques. Conclusions: The absence of complete homogeneity among participants showed the need for prospective randomized studies to set up stronger guidelines for classification, management, surgical treatment, rehabilitation, and pharmacological support of periprosthetic femoral fractures.

Diagnostic Performance of Dual-Energy CT for Detecting Painful Hip Prosthesis Loosening.

Background Revisions of hip prostheses are increasing, and conventional radiography (CR) is a primary tool for managing -complications. However, dual-energy CT (DECT) with virtual monoenergetic imaging is capable of reducing periprosthetic metal artifacts compared with standard CT. Purpose To compare the diagnostic performance of DECT and CR in detecting hip prosthesis loosening, using surgery as a reference for diagnosis. Materials and Methods This retrospective single-center study conducted between January 2018 and October 2020 included -consecutive patients with unilateral painful hip prostheses. Two independent readers (with 15 years and 4 years of experience) who were blinded to clinical findings evaluated CR and DECT images. At imaging, diagnosis of loosening prosthesis was made for -periprosthetic radiolucency greater than or equal to 2 mm wide or the presence of two or more secondary findings, including -periprosthetic osteolysis, angulation of the implant, fracture, or abnormal periosteal reaction. For each reader and for each imaging parameter, -sensitivity and specificity were calculated. The diagnostic performance of each imaging tool was compared by using the McNemar test. Interobserver agreements were calculated with Cohen κ statistics. Statistical software was used. Results Overall, 178 patients (mean age ± standard deviation, 74 years ± 20; 96 men) were included (121 undergoing surgery, 57 follow-up). Overall, 87 of 178 patients (49%) were diagnosed with a loosened prosthesis. DECT had higher sensitivity and specificity than CR for both reader 1 (94% [82 of 87 examinations; 95% CI: 87, 98] and 93% [85 of 91 examinations; 95% CI: 86, 97] vs 84% [73 of 87 examinations; 95% CI: 74, 91] and 91% [83 of 91 examinations; 95% CI: 83, 96], respectively; P < .001) and reader 2 (92% [80 of 87 examinations; 95% CI: 84, 97] and 95% [86 of 91 examinations; 95% CI: 88, 98] vs 80% [70 of 87 -examinations; 95% CI: 71, 88] and 91% [83 of 91 examinations; 95% CI: 83, 96], respectively; P = .001), with better interobserver agreement (κ, 0.88 [95% CI: 0.81, 0.95] vs 0.78 [95% CI: 0.69, 0.88]). Conclusion Dual-energy CT showed better diagnostic performance than conventional radiography in diagnosing hip prosthesis loosening. See also the editorial by Lutz in this issue. © RSNA, 2021.

MR arthrography of the hip: evaluation of isotropic 3D intermediate-weighted FSE and hybrid GRE T1-weighted sequences.

PURPOSE: To compare the diagnostic performance of three-dimensional (3D) intermediate-weighted FSE (IW-3D) and 3D hybrid T1-weighted sequences (Hy-3D) and 2D fast-spin-echo sequences (FSE) in diagnosing chondral and labral lesions at 1.5 Tesla hip MR arthrography (MRA). MATERIALS AND METHODS: Institutional review board approval was obtained and informed consent was waived. Ninety-two consecutive patients were evaluated. Chondral and labral lesions were retrospectively and independently evaluated by two radiologists. Intra-operative findings were used as the reference standard (arthroscopy = 73, open surgery = 19). Sensitivity (Se), specificity (Sp), and accuracy (Acc) values that obtained were compared using McNemar test. A value of p < 0.05 was considered statistically significant. Inter-observer agreement was calculated using kappa statistics. RESULTS: Surgeons revealed 81 labrum and 44 chondral lesions, respectively. The highest Se, Sp, and Acc for Reader 1 were 96.3, 90.9, and 95.6%, respectively, in evaluating labral lesions (by reading 2D data set) and 90.9, 100, and 95.7% in evaluating chondral lesions (by reading IW-3D images). The highest Se, Sp, and Acc for Reader 2 were 93.8, 81.8, and 92.4% in evaluating labral lesions (using 2D images) and 88.6, 97.9, and 93.5%, respectively, in evaluating chondral lesions (using Hy-3D). The difference of diagnostic accuracy achieved was not significant (p > 0.05). A near-perfect inter-observer agreement was achieved by reading 2D data set (k = 0.88) and Hy-3D (k = 0.83) and IW-3D (k = 0.85). CONCLUSIONS: At 1.5 Tesla hip MRA, the accuracy of IW-3D and Hy-3D images was not significantly higher than the 2D sequences in evaluating acetabular labrum and chondral lesions.

Surgical hip dislocation for anatomic reorientation of slipped capital femoral epiphysis: preliminary results.

Controversies exist regarding the best treatment for slipped capital femoral epiphysis (SCFE). Subcapital anatomical reorientation of the epiphysis by surgical dislocation and a retinacular soft tissue flap has been described recently as an effective approach. We evaluated the clinical and radiographic efficacy of this technique and compared these to published results. A series of 20 SCFE (18 stable, 2 unstable) treated by subcapital re-orientation through surgical hip dislocation and an extended retinacular soft tissue flap was reviewed retrospectively. Preoperatively and at most recent follow-up, patients were clinically examined with regard to pain and function according to the Harris hip score and to the Western Ontario and McMaster universities (WOMAC) score. Radiological examination included measurement of preoperative and postoperative anteroposterior (AP) and lateral (L) Southwick angles; and at follow-up the alpha angle was measured. The average follow-up time was 24 months. The mean WOMAC score was 2.80 post-operatively. The mean pre-operative slip angle was 40.2 degrees on the AP view and 50.65 degrees on the lateral view. Post-operatively, the mean values were 7,20 degrees on the AP view and 9,45 degrees on the lateral view. The mean post-operative average alpha angle was 43,11 degrees. No cases of avascular necrosis were seen. Our short term clinical and radiographic results are similar to outcomes published in the recent literature. The small number of technical complications appears favourable considering the surgical complexity of the procedure, and our technique offers clear advantages in treating these complex deformities.