Evaluation of the efficacy of modal analysis in predicting the pullout strength of fixation bone screws

Abstract Background Pilot hole preparation has been shown to have an impact on the short and long‐term stability of the screw fixation constructs. Purpose Investigation and comparison of two nondestructive modal analysis methods with conventional insertion torque (IT) and pullout tests in optimum pilot hole diameter detection. Methods Twenty conical core titanium screws were embedded in high‐density polyethylene blocks with different pilot hole diameters. The maximum IT was recorded for each screw during implantation. Then, two modal analysis methods including accelerometer (classical modal analysis [CMA]) and acoustic modal analysis (AMA) were carried out to measure the natural frequency (NF) of the bone‐screw structure. Finally, stiffness (S), pullout force (Fult), displacement at Fult (dult) and energy dissipation (ED) were obtained from the destructive pullout test. Results The IT increased, as the pilot hole diameter decreased. The maximum value of IT was observed in the smallest pilot hole diameter. The same trend was found for the Fult and the first NF derived from both modal methods except for 5.5 mm pilot hole diameter. The natural NFs derived from CMA and AMA showed high correlations in different groups (R2 = 0.94) and did not deviate from y = x hypothesis in linear regression analysis. The Fult, dult, and ED were measured 4800 ± 172 N, 3.10 ± 0.08 mm and 14.23 ± 1.10 N.mm, respectively. Discussion No significant change was observed in “S” between the groups. The highest Fult and first NF were obtained for the 5.5 mm pilot hole diameter. Both CMA and AMA were found to be reliable methods and can promote the undesirable contradiction between Fult and IT

Do not Mask Randomly: Effective Domain-adaptive Pre-training by Masking In-domain Keywords

We propose a novel task-agnostic in-domain pre-training method that sits between generic pre-training and fine-tuning. Our approach selectively masks in-domain keywords, i.e., words that provide a compact representation of the target domain. We identify such keywords using KeyBERT (Grootendorst, 2020). We evaluate our approach using six different settings: three datasets combined with two distinct pre-trained language models (PLMs). Our results reveal that the fine-tuned PLMs adapted using our in-domain pre-training strategy outperform PLMs that used in-domain pre-training with random masking as well as those that followed the common pre-train-then-fine-tune paradigm. Further, the overhead of identifying in-domain keywords is reasonable, e.g., 7-15% of the pre-training time (for two epochs) for BERT Large (Devlin et al., 2019).Comment: final version: accepted at ACL'23 RepL4NLP. arXiv admin note: text overlap with arXiv:2208.1236

Coxa valga and antetorta increases differences among different femoral version measurements : potential implications for derotational femoral osteotomy planning.

AIMS To evaluate how abnormal proximal femoral anatomy affects different femoral version measurements in young patients with hip pain. METHODS First, femoral version was measured in 50 hips of symptomatic consecutively selected patients with hip pain (mean age 20 years (SD 6), 60% (n = 25) females) on preoperative CT scans using different measurement methods: Lee et al, Reikerås et al, Tomczak et al, and Murphy et al. Neck-shaft angle (NSA) and α angle were measured on coronal and radial CT images. Second, CT scans from three patients with femoral retroversion, normal femoral version, and anteversion were used to create 3D femur models, which were manipulated to generate models with different NSAs and different cam lesions, resulting in eight models per patient. Femoral version measurements were repeated on manipulated femora. RESULTS Comparing the different measurement methods for femoral version resulted in a maximum mean difference of 18° (95% CI 16 to 20) between the most proximal (Lee et al) and most distal (Murphy et al) methods. Higher differences in proximal and distal femoral version measurement techniques were seen in femora with greater femoral version (r > 0.46; p 0.37; p = 0.008) between all measurement methods. In the parametric 3D manipulation analysis, differences in femoral version increased 11° and 9° in patients with high and normal femoral version, respectively, with increasing NSA (110° to 150°). CONCLUSION Measurement of femoral version angles differ depending on the method used to almost 20°, which is in the range of the aimed surgical correction in derotational femoral osteotomy and thus can be considered clinically relevant. Differences between proximal and distal measurement methods further increase by increasing femoral version and NSA. Measurement methods that take the entire proximal femur into account by using distal landmarks may produce more sensitive measurements of these differences.Cite this article: Bone Jt Open 2022;3(10):759-766

Hip Impingement of severe SCFE patients after in situ pinning causes decreased flexion and forced external rotation in flexion on 3D-CT

Introduction: In situ pinning is an accepted treatment for stable slipped capital femoral epiphysis. However, residual deformity of severe slipped capital femoral epiphysis can cause femoroacetabular impingement and forced external rotation. Purpose/questions: The aim of this study was to evaluate the (1) hip external rotation and internal rotation in flexion, (2) hip impingement location, and (3) impingement frequency in early flexion in severe slipped capital femoral epiphysis patients after in situ pinning using three-dimensional computed tomography. Patients and methods: A retrospective Institutional Review Board-approved study evaluating 22 patients (26 hips) with severe slipped capital femoral epiphysis (slip angle > 60°) using postoperative three-dimensional computed tomography after in situ pinning was performed. Mean age at slipped capital femoral epiphysis diagnosis was 13 ± 2 years (58% male, four patients bilateral, 23% unstable, 85% chronic). Patients were compared to contralateral asymptomatic hips (15 hips) with unilateral slipped capital femoral epiphysis (control group). Pelvic three-dimensional computed tomography after in situ pinning was used to generate three-dimensional models. Specific software was used to determine range of motion and impingement location (equidistant method). And 22 hips (85%) underwent subsequent surgery. Results: (1) Severe slipped capital femoral epiphysis patients had significantly (p < 0.001) decreased hip flexion (43 ± 40°) and internal rotation in 90° of flexion (−16 ± 21°, IRF-90°) compared to control group (122 ± 9° and 36 ± 11°). (2) Femoral impingement in maximal flexion was located anterior to anterior–superior (27% on 3 o’clock and 27% on 1 o’clock) of severe slipped capital femoral epiphysis patients and located anterior to anterior–inferior (38% on 3 o’clock and 35% on 4 o’clock) in IRF-90°. (3) However, 21 hips (81%) had flexion < 90° and 22 hips (85%) had < 10° of IRF-90° due to hip impingement and 21 hips (81%) had forced external rotation in 90° of flexion (< 0° of IRF-90°). Conclusion: After in situ pinning, patient-specific three-dimensional models showed restricted flexion and IRF-90° and forced external rotation in 90° of flexion due to early hip impingement and residual deformity in most of the severe slipped capital femoral epiphysis patients. This could help to plan subsequent hip preservation surgery, such as hip arthroscopy or femoral (derotation) osteotomy

Limited Hip Flexion and Internal Rotation Resulting From Early Hip Impingement Conflict on Anterior Metaphysis of Patients With Untreated Severe SCFE Using 3D Modelling.

INTRODUCTION Slipped capital femoral epiphysis (SCFE) is the most common hip disorder in adolescent patients that can result in complex 3 dimensional (3D)-deformity and hip preservation surgery (eg, in situ pinning or proximal femoral osteotomy) is often performed. But there is little information about location of impingement.Purpose/Questions: The purpose of this study was to evaluate (1) impingement-free hip flexion and internal rotation (IR), (2) frequency of impingement in early flexion (30 to 60 degrees), and (3) location of acetabular and femoral impingement in IR in 90 degrees of flexion (IRF-90 degrees) and in maximal flexion for patients with untreated severe SCFE using preoperative 3D-computed tomography (CT) for impingement simulation. METHODS A retrospective study involving 3D-CT scans of 18 patients (21 hips) with untreated severe SCFE (slip angle>60 degrees) was performed. Preoperative CT scans were used for bone segmentation of preoperative patient-specific 3D models. Three patients (15%) had bilateral SCFE. Mean age was 13±2 (10 to 16) years and 67% were male patients (86% unstable slip, 81% chronic slip). The contralateral hips of 15 patients with unilateral SCFE were evaluated (control group). Validated software was used for 3D impingement simulation (equidistant method). RESULTS (1) Impingement-free flexion (46±32 degrees) and IRF-90 degrees (-17±18 degrees) were significantly (P<0.001) decreased in untreated severe SCFE patients compared with contralateral side (122±9 and 36±11 degrees).(2) Frequency of impingement was significantly (P<0.001) higher in 30 and 60 degrees flexion (48% and 71%) of patients with severe SCFE compared with control group (0%).(3) Acetabular impingement conflict was located anterior-superior (SCFE patients), mostly 12 o'clock (50%) in IRF-90 degrees (70% on 2 o'clock for maximal flexion). Femoral impingement was located on anterior-superior to anterior-inferior femoral metaphysis (between 2 and 6 o'clock, 40% on 3 o'clock and 40% on 5 o'clock) in IRF-90 degrees and on anterior metaphysis (40% on 3 o'clock) in maximal flexion and frequency was significantly (P<0.001) different compared with control group. CONCLUSION Severe SCFE patients have limited hip flexion and IR due to early hip impingement using patient-specific preoperative 3D models. Because of the large variety of hip motion, individual evaluation is recommended to plan the osseous correction for severe SCFE patients. LEVEL OF EVIDENCE Level III

Validation of Porcine Knee as a Sex-specific Model to Study Human Anterior Cruciate Ligament Disorders

Abstract Background Animal models have long been considered an important modality for studying ACL injuries. However, to our knowledge, the value of these preclinical models to study sex-related phenomena associated with ACL injury and recovery has not been evaluated. Questions/purposes We asked whether (1) prominent anatomic and (2) biomechanical factors differ between female and male porcine knees, particularly those known to increase the risk of ACL injury. Methods Eighteen intact minipig knees (nine males, nine females) underwent MRI to determine the femoral bicondylar width, intercondylar notch size (width, area and index), medial and lateral tibial slope, ACL size (length, cross-sectional area, and volume), and medial compartment tibiofemoral cartilage thickness. AP knee laxity at 30°, 60°, and 90°flexion and ACL tensile structural properties were measured using custom-designed loading fixtures in a universal tensile testing apparatus. Comparisons between males and females were performed for all anatomic and biomechanical measures. The findings then were compared with published data from human knees. Results Female pigs had smaller bicondylar widths (2.9 mm, ratio = 0.93, effect size = À1.5) and intercondylar notches (width: 2.0 mm, ratio = 0.79, effect size = À2.8; area: 30.8 mm 2 , ratio = 0.76, effect size = 2.1; index: 0.4, ratio = 0.84, effect size = À2.0), steeper lateral tibial slope (4.3°, ratio = 1.13, effect size = 1.1), smaller ACL (length: 2.7 mm, ratio = 0.91, effect size = 1.1; area: 6.8 mm 2 , ratio = 0.74, effect size = À1.5; volume: 266.2 mm 3 , ratio = 0.68, effect size = À1.5), thinner medial femoral cartilage (0.4 mm, ratio = 0.8, effect size = À1.1), lower ACL yield load (275 N, ratio = 0.81, effect size = À1.1), and greater AP knee laxity at 30°( 0.7 mm, ratio = 1.32, effect size = 1.1) and 90°(0.5 mm, ratio = 1.24, effect size =

Age and Sex Dependent Variations in Knee Anatomy During Skeletal Maturation in Children and Adolescents

Knee joint is the most common site of injury in children and adolescents and accounts for up to 60% of all sports-related injuries in this population. Ruptures of the anterior cruciate ligament (ACL) are among the most frequent knee injuries in pediatric population with up to 10 times greater prevalence in females than males. These injuries are often immediately disabling and are associated with significant short- and long-term clinical compilations such as increased risk of posttraumatic osteoarthritis (OA), despite our best current treatment methods. Several unique anatomical features of the knee joint, including tibial slope and femoral notch size, have shown to affect joint and ACL loading and risk of injury. Despite the well-established role of these anatomical features on ACL injury risk, it remains unclear how these anatomical features change during skeletal growth and maturation. We are proposing to systematically investigate how age and sex affect multiple prominent anatomical features of the knee joint in children and adolescents. This will be done retrospectively by analyzing the Magnetic Resonance (MR) images of the knees of patients who underwent a knee MRI at Boston Children’s Hospital. The 3D MR image stacks will be used to measure a comprehensive set of anatomical indices of the knee joint based on previously established techniques. The associations between age and each of the quantified anatomical indices will be assessed. The age-dependent changes in knee anatomy will be compared between boys and girls as well as between those who had an ACL injury and those with healthy uninjured knees. Findings will help to better understand how prominent anatomical features of the knee joint, in particular those identified as risk factors for ACL injury, are being developed and/or changed during skeletal growth and maturation. Findings will also improve our knowledge of how sex may affect the age dependent changes in knee anatomy. The outcomes of this work will improve our knowledge on how and when anatomy becomes different between subjects at low risk of ACL injury and “at risk” population. Such improved knowledge can be used to develop novel risk screening models to more effectively identify children at high risk of ACL injury based on their anatomical profile. Individuals with high-risk bony anatomy can be subjected to neuromuscular and biomechanical interventions early on to minimize their risk of sustaining and ACL tear

Structural and Anatomic Restoration of the Anterior Cruciate Ligament Is Associated With Less Cartilage Damage 1 Year After Surgery: Healing Ligament Properties Affect Cartilage Damage

Background: Abnormal joint motion has been linked to joint arthrosis after anterior cruciate ligament (ACL) reconstruction. However, the relationships between the graft properties (ie, structural and anatomic) and extent of posttraumatic osteoarthritis are not well defined. Hypotheses: (1) The structural (tensile) and anatomic (area and alignment) properties of the reconstructed graft or repaired ACL correlate with the total cartilage lesion area 1 year after ACL surgery, and (2) side-to-side differences in anterior-posterior (AP) knee laxity correlate with the total cartilage lesion area 1 year postoperatively. Study Design: Controlled laboratory study. Methods: Sixteen minipigs underwent unilateral ACL transection and were randomly treated with ACL reconstruction or bridge-enhanced ACL repair. The tensile properties, cross-sectional area, and multiplanar alignment of the healing ACL or graft, AP knee laxity, and cartilage lesion areas were assessed 1 year after surgery. Results: In the reconstructed group, the normalized graft yield and maximum failure loads, cross-sectional area, sagittal and coronal elevation angles, and side-to-side differences in AP knee laxity at 60° of flexion were associated with the total cartilage lesion area 1 year after surgery (R 2 > 0.5, P 0.5, P < .05). Smaller cartilage lesion areas were observed in the surgically treated knees when the structural and anatomic properties of the ligament or graft and AP laxity values were closer to those of the contralateral ACL-intact knee. Reconstructed grafts had a significantly larger normalized cross-sectional area and sagittal elevation angle (more vertical) when compared with repaired ACLs (P < .02). Conclusion: The tensile properties, cross-sectional area, and multiplanar alignment of the healing ACLs or grafts and AP knee laxity in reconstructed knees were associated with the extent of tibiofemoral cartilage damage after ACL surgery. Clinical Relevance: These data highlight the need for novel ACL injury treatments that can restore the structural and anatomic properties of the torn ACL to those of the native ACL in an effort to minimize the risk of early-onset posttraumatic osteoarthritis