Lachman, Nirusha

Abstract Objective. Four-dimensional CT (4DCT) enables visualization of dynamic wrist joint pathology but may be compromised by motion artifacts. Deep learning (DL)-assisted motion correction has the potential to enhance wrist 4DCT quality, but model development is hindered by scarce training data. To address this, we developed a model-based motion simulation framework that generated realistic 4DCT data with paired static ground truth images to demonstrate wrist motion correction using a physics-informed DL model trained with simulated data. Approach. Wrist motion was simulated by synchronizing rotational and translational movements of carpal bones and connective tissues. Elastic deformation guided by analytically-derived motion vector fields was applied to static wrist scans at neutral positions to create artifact-free images at multiple angular positions. Virtual motion-corrupted 4DCT images were produced via forward projection and reconstruction with synchronized gantry and wrist motion. Experimental data from 4DCT cadaver scans were collected to validate simulation quality. Low-intensity region score (LIRS), positivity, and entropy were used to assess simulated motion artifacts. A physics-informed motion correction network was adapted exclusively using simulated training data and subsequently deployed on simulated, real cadaveric, and in vivo 4DCT scans. LIRS and structural similarity index (SSIM) were used to evaluate motion correction quality. Wilcoxon signed-rank tests were conducted ( α = 0.05). Results. The simulation method created realistic motion artifacts compared to real scan reference ( p > 0.05). Motion artifacts were effectively mitigated across testing cases demonstrating generalizability. In simulated scans, LIRS improved from 0.55 ± 0.12–0.75 ± 0.04 and SSIM from 0.87 ± 0.08–0.95 ± 0.03 at bone regions (each p < 0.01). In experimental cadaveric scans, LIRS improved from 0.05 ± 0.01–0.31 ± 0.17 in marker regions and from 0.58 ± 0.19–0.77 ± 0.14 in bone regions (each p < 0.01). Significance. Our simulation method facilitates training DL-assisted motion correction algorithms by providing high-quality training data, effectively supporting 4DCT image quality enhancement.

ABSTRACT The hip capsule is a dense, fibrous structure that plays a crucial role in providing hip stability. Its biomechanical function is tied to its complex anatomy, which includes the iliofemoral, pubofemoral, and ischiofemoral ligaments, along with the circumferential fibers of the zona orbicularis. Anatomic and biomechanical studies with advanced imaging and arthroscopic techniques have provided better understanding of the capsular morphology and its contribution to hip stability. Additionally, these studies provide insight into how capsulotomy and subsequent capsular management at the time of hip arthroscopy can potentially influence postoperative outcomes. Growing clinical evidence supports capsular preservation and repair at the time of primary hip arthroscopy and demonstrates the potential negative outcomes of capsular deficiency, such as pain, dysfunction, and instability. This review provides a comprehensive overview of the gross, arthroscopic, radiologic, and biomechanical anatomy of the hip capsule.

Abstract Classically described repairs for helical rim defects include granulation, linear closure, wedge repair, full-thickness skin grafts, helical rim advancement flaps, and two-stage interpolation flaps. The bilateral bidirectional O to Z rotation flap (O to Z flap) is commonly used for large defects on the scalp. The purpose of this study is to examine the clinical and cosmetic outcomes of O to Z flap repairs to the helical rim. The flap was created by incising above and below the defect along the helical rim on opposite sides of the defect to the depth of the perichondrium. Back cuts were performed to facilitate movement along with extensive undermining. The bilateral flaps were rotated into the defect from either end meeting in the defect middle and sutured into place with a running 5–0 FAG. In total, 50 O to Z flap repairs for helical rim defects following Mohs micrographic surgery were performed. Defect depths ranged from subcutaneous fat to through cartilage. The defect size ranged from 0.9 × 0.7 cm to 2.5 × 1.4 cm. The flap repair size ranged from 1.5 × 1.2 cm to 5.1 × 2.1 cm (average size 5.1 cm2). The median follow-up was 6 weeks (range 2 weeks to 2 years). Complications were as follows: 4% (2 of 50) of cases had bleeding requiring intervention, 16% (8 of 50) of cases had partial superficial flap necrosis, and 22% (11 of 50) of cases had mild persistent tenderness at 6 weeks. Cosmetic outcomes were graded on a scale of poor, acceptable, good or excellent. Overall, 78% (39 of 50) were rated good to excellent, 20% (10 of 50) were rated acceptable, and 2% (1 of 50) were rated poor, but did not require revision. The O to Z flap is a reliable repair for helical rim defects. Flap downsides include persistent cartilage tenderness and risk of minor flap necrosis.

ABSTRACT Based on anecdotal observation of fatty infiltration (FI) of the opponens pollicis (OPP) muscle in patients with thumb carpometacarpal (CMC) Osteoarthritis (OA), we sought to examine the association of FI with CMC OA. We reviewed 747 consecutive 3 T wrist magnetic resonance imaging (MRI) studies for evidence of FI in the thenar muscles. This population was divided into two cohorts based on radiographic analysis: a cohort without thumb CMC OA ( n = 440) and a second cohort with thumb CMC OA ( n = 307), staged according to the Eaton–Littler classification. Statistical analysis using logistic regression was performed to investigate clinical factors associated with the presence of FI in the thenar muscles. FI was present in 133 patients with CMC OA (43.3%). FI, when present, was located only in the OPP. We found no OPP FI in the cohort without CMC OA (440 patients). Among patients with CMC OA, increasing age, male sex and advanced OA stage were significantly associated with the presence of OPP FI. OPP FI is a frequent finding in CMC OA. This FI could affect the biomechanical function of the OPP. In the future, we plan to analyze clinical outcomes in CMC OA patients with and without FI, and more focused in vivo studies of OPP function. OPP FI could potentially affect the function and the stability of the thumb CMC joint in patients with CMC OA. Orthopaedic Research Society. Journal of Orthopaedic Research® 00:00–00, 2026.

Background Dermatofibrosarcoma protuberans (DFSP) arising in the vulvar and perivulvar region poses unique challenges to the dermatologic surgeon. The potential for broad subclinical extension and involvement of deeper and high-risk functional structures requires a strong knowledge of relevant anatomy. Careful considerations are required for preoperative arrangements, surgical day preparations, and postoperative surveillance to improve treatment outcomes and patient experiences. Objective The authors aim to provide a practical guide for the dermatologic surgeon, which outlines surgical planning and management recommendations for vulvar DFSP. Emphasis on pelvic anatomy through cadaveric and patient images as well as anatomical illustrations will be included. Materials and Methods A literature review was performed to identify evidence-based management recommendations for vulvar DFSP. Authors share anecdotal perioperative recommendations for optimizing the patient experience. A detailed pelvic dissection of a female cadaver was performed for anatomical depiction of relevant high-risk structures. Illustrations of sensory nerve distributions were created for reference. Conclusion Vulvar DFSP is a challenging cutaneous tumor in a sensitive anatomical location. As Mohs surgery offers clear advantages over wide local excision, the authors provide dermatologic surgeons with detailed anatomy review resources as well as recommendations and considerations for management and perioperative planning for this specialized site.

Summary: Anatomy is a critical component of surgical training; however, traditional resources—such as Netter’s Surgical Anatomy , Gray’s Anatomy , and anatomy applications—often fall short in delivering surgically relevant, 3-dimensional (3D) perspectives of facial anatomy. Although cadaveric dissection remains a valuable teaching tool, its accessibility is limited by cost, ethical concerns, and the lack of structured curricula, making it less feasible for ongoing surgical education. To address these limitations, this article introduced a novel educational approach that integrates 3D photogrammetry and virtual reality technology into the surgical anatomy curriculum for craniofacial and aesthetic surgery. Six fresh cadaveric specimens were meticulously dissected by a plastic surgeon to illustrate the intricate layered anatomy of the face and neck. At each stage of the dissection, a photogrammetry technique was used to capture 360-degree images using 5 digital single-lens reflex cameras alongside a 3D handheld camera. This approach not only ensured high-quality imaging but also facilitated the creation of detailed, lifelike virtual 3D models, enhancing the understanding of facial and neck anatomy within a surgical context. Additionally, we present some technical refinements of the 3D volume renderings to capture precise anatomical details during our dissections. Preliminary results from the use of this technology in anatomy courses and workshops indicated trainee engagement, a clearer grasp of the spatial anatomical relationships, and greater confidence in applying this knowledge to hands-on surgical procedures.

Introduction Superficial parasternal intercostal plane blocks have grown in clinical use for cardiac surgery as a targeted fascial plane block for median sternotomy. Despite this, there remains no consensus on technique for optimal parasternal spread of injectate. The primary objective of this cadaveric study was to evaluate parasternal spread of injectate of single versus two-level superficial parasternal intercostal plane injections with the needle tip positioned on the anterior surface of the costal cartilage. Methods We performed 10 single-level injections at T4 and 10 two-level injections at T3 and T5 on alternating sides in 10 fresh frozen cadavers. All injections were ultrasound guided with a parasagittal ultrasound probe orientation and an in-plane needle orientation. Anatomic dissections were performed immediately following injections. Results Parasternal spread of injectate was greater with two-level injections at T3 and T5 costal cartilages than with single-level injections at the T4 costal cartilage, with two-level injections consistently spreading to the T2–T5 intercostal spaces. Median (Q1, Q3) intercostal space spread for single-level injections was 2.0 (2.0–2.5). Median (Q1, Q3) intercostal space spread for two-level injections was 4.0 (4.0–4.375). Conclusions Two-level injections with the needle tip located on the anterior surface of the costal cartilage resulted in improved parasternal spread compared with single-level injections.