Block QT Research Articles

Paper 40: Early Clinical Outcomes Following Anterior Cruciate Ligament Reconstruction with Quadriceps Tendon Autograft in an Adolescent Population Suggest Higher Rates of Arthrofibrosis with Bone-Block than All Soft Tissue.

Objectives: There is an increased interest in quadriceps tendon autograft for anterior cruciate ligament (ACL) reconstruction in the adolescent population. It has emerged as a promising graft option that can be harvested with a bone-block (BB) or all soft tissue (AST). The preferred quadriceps graft remains controversial as there is evidence that bone to bone healing is stronger and faster, while AST grafts reportedly have a lower complication rate. The purpose of this study is to report early clinical outcomes following ACL reconstruction with BB versus AST quadriceps autograft in adolescent population. We hypothesized that both techniques would provide similar early clinical outcomes. Methods: A retrospective case-controlled study of patients under 20 years of age who underwent arthroscopic ACL reconstruction utilizing quadriceps tendon autograft from September 2017 to September 2021 was conducted. The cohort was divided in two groups: Group 1 included 35 patients who underwent ACL reconstruction with BB quadriceps tendon autograft. Group 2 included 58 patients who underwent ACL reconstruction with AST quadriceps tendon autograft. Data collected included demographics, range of motion, graft measurements, concomitant procedures, perioperative complications and arthrofibrosis rate, defined as reoperation for lysis of adhesions. Knee strength was objectively recorded at 3 months postoperatively using an isokinetic dynamometer (Humac, CSMI USA, Stoughton, MA, USA) and was used to calculate the Limb Symmetry Index (LSI), or the ratio between the involved limb and uninvolved limb and expressed as a percentage. Patient reported outcomes include International Knee Documentation Committee (IKDC) and Anterior Cruciate Ligament Return to Sport After Injury (ACL-RSI) scale. Statistical analyses were then performed to compare groups. Results: A total of 93 patients were included for analysis, with mean age of 15.9 (range 10-20) and mean follow-up 17 months (ranged from 3 to 25). There was no difference between the study and control groups regarding age (p=0.10), BMI (p=0.70), concomitant procedures (p=0.39), but there was a predominance in females in group 1 (bone block) (64.9% vs 43.3%, p=0.02). The group 1(bone block) was associated with higher rate of arthrofibrosis with odds ratio of 3.98 (7/35 20% vs 3/58 5%, p=0.02) and lower LSI (55.6% vs 68.4%, p=0.01) at 3 months postoperatively. Group 1 (bone block) grafts were overall greater in femur width (9.47 vs 9.19, p=0.02), and length (69.85 vs 65.12, p=0.01). Logistic regression found BB quadriceps tendon graft (p=0.03) and extension deficit at 3 months postoperatively (p=0.01) the only risk factors for arthrofibrosis. Patients in group 1 (bone block) reported lower outcomes scores than group 2 (all soft tissue), measured by IKDC 63.94 vs 75.27 (p=0.01) and (ACL-RSI) 49.55 vs 63.25 (p=0.01) at 3 months postoperatively. Conclusions: Comparative analysis between bone block and all soft tissue quadriceps tendon autograft for ACL reconstruction in an adolescent population demonstrates that bone block QT autograft is associated with 4 times higher rate of arthrofibrosis requiring operative intervention for lysis of adhesions. If surgeons opted for a bone block QT autograft for ACL reconstruction in the adolescent population, our findings suggest that an early rehabilitation program with a focus on early restoration of full knee extension should be implemented in order to avoid arthrofibrosis.

Low-complexity QTMT partition based on deep neural network for Versatile Video Coding

Versatile Video Coding (VVC), the newest standard for future video coding, is currently under development. This proposal aimed to improve the encoder performance over the latest standard namely High Efficiency Video Coding, carried with a high increase in coding complexity. The VVC partition structure is mainly based on the quadtree with nested multi-type tree (QTMT) block scheme. Such an improvement leads to a more flexible block partition and promotes a high encoding efficiency, but generates a huge coding complexity. In order to deal with this issue, a fast QTMT intra partition algorithm, based on a deep neural network named Early Terminated Hierarchical Convolution Neural Network, is applied to predict the $$64\times $$ 64 block QT partition structure. The proposed algorithm determines the QTMT partition structure based on the decision of whether to split or skip the corresponding CU, in order to get $$128\times $$ 128 Coding Tree Unit partition architecture. In this paper, the proposed intra partition work achieves a significant speedup in encoding gain that reaches 32.96% in best cases for Ultra High Definition video sequences compared to the reference VVC software VTM-3.0. For all video sequences, 24.49% time saving is reached on average. This improvement comes with an increase of 4.18% and a decrease of 0.18 dB in terms of BDBR and BDPSNR, respectively.

3D block QT inversion of surface nuclear magnetic resonance data

Surface nuclear magnetic resonance (surface NMR) has up to now rarely been applied to 3D subsurface modeling. Inversion approaches currently in use are smooth inversion techniques that are not useful for identifying sharp geologic boundaries. Although they are already computationally expensive, the resulting models are restricted to imaging the subsurface water content distribution and do not deliver relaxation times [Formula: see text] based on the QT inversion scheme established elsewhere. We have developed a method of 3D block QT inversion that uses horizontal smoothness constraints to resolve sharp boundaries in the vertical direction and the distributions of the water content and relaxation time [Formula: see text]. We have improved the computational efficiency, i.e., the ability to perform the inversion using a common desktop computer, by gating the surface NMR data, reducing the model space to monoexponential decays within the subsurface bodies, and inverting based on blocklike structures instead of smooth distributions. We have developed a synthetic study to assess the effectiveness of our block QT inversion technique in imaging 3D water content distributions, and we compared the results with those of a smooth inversion. Furthermore, we evaluated results from a field survey conducted on the frozen surface of an artificial lake. We found that our block QT inversion approach provides results that are superior to those of smooth inversion and consistent with the available construction plan of the lake. We expect that 3D block QT inversion will be a useful approach also in other geologic settings, such as buried valleys, because it overcomes the current limitations of applying 3D surface NMR inversion.