Parametrizing the genioplasty: a biomechanical virtual study on soft tissue behavior

Purpose Sliding genioplasty is used to surgically correct a retruded or misaligned chin: in this procedure, an osteotomy is performed and the bony segment is repositioned. In this study we investigate the effect of surgical parameters (bony segment movement, osteotomy design) on postop soft tissue changes in a patient cohort. Methods Seven patients were retrospectively recruited. Cone beam computed tomography data were obtained and soft tissue and bone shape reconstructions were performed. 3D models were created and surgical cuts were replicated according to postop scans. Each model was imported in ANSYS 2019R1 (Ansys Inc, USA) for simulation: the effect of variation in osteotomy plane as well as extent of bony segment movement were assessed by means of design of experiment: surgical parameters were varied in a surgically acceptable range and the soft tissue predictions were evaluated as displacement output of five craniometric landmarks. Results Simulation results show the overall changes of the lower third of the face are sensitive to changes in horizontal and vertical displacement of the bony segment as well as segment rotation. No significant changes in the soft tissue response were to attribute to the osteotomy design. Conclusions Our results are consistent with experimental findings reported in the literature: when planning genioplasty in orthognathic surgery, particular focus on the segment movement (horizontal translation, vertical translation and rotation), rather than on the design of the osteotomy itself, should be considered.

Bone-to-Brain: A Round Trip in the Adaptation to Mechanical Stimuli

Besides the classical ones (support/protection, hematopoiesis, storage for calcium, and phosphate) multiple roles emerged for bone tissue, definitively making it an organ. Particularly, the endocrine function, and in more general terms, the capability to sense and integrate different stimuli and to send signals to other tissues, has highlighted the importance of bone in homeostasis. Bone is highly innervated and hosts all nervous system branches; bone cells are sensitive to most of neurotransmitters, neuropeptides, and neurohormones that directly affect their metabolic activity and sensitivity to mechanical stimuli. Indeed, bone is the principal mechanosensitive organ. Thanks to the mechanosensing resident cells, and particularly osteocytes, mechanical stimulation induces metabolic responses in bone forming (osteoblasts) and bone resorbing (osteoclasts) cells that allow the adaptation of the affected bony segment to the changing environment. Once stimulated, bone cells express and secrete, or liberate from the entrapping matrix, several mediators (osteokines) that induce responses on distant targets. Brain is a target of some of these mediator [e.g., osteocalcin, lipocalin2, sclerostin, Dickkopf-related protein 1 (Dkk1), and fibroblast growth factor 23], as most of them can cross the blood-brain barrier. For others, a role in brain has been hypothesized, but not yet demonstrated. As exercise effectively modifies the release and the circulating levels of these osteokines, it has been hypothesized that some of the beneficial effects of exercise on brain functions may be associated to such a bone-to-brain communication. This hypothesis hides an interesting clinical clue: may well-addressed physical activities support the treatment of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s diseases?

Anterior Median Skull Base Reconstruction Using a Vascularized Free Flap: Rationale, Patient Selection and Outcome

Objectives To present our method of median anterior skull base (ASB) reconstruction using a subcranial approach with a free flap in cases of naso-fronto-orbital (NFO) bony segment failure and in patients at high risk for future failure of the bony frontal segment. Design This study presents as a retrospective case series. Setting Tertiary university-affiliated medical center. Participants Adult and pediatric patients who underwent median ASB resection via the subcranial approach with a free flap reconstruction were participated in this study. Main Outcome Measures Pathologic outcome and postoperative quality of life (QoL) as assessed by a validated Hebrew version of the “Anterior Skull Base Quality-of-Life Questionnaire.” Results The departmental database yielded 13 suitable patients aged between 15 and 70 years. The main indication (n = 7) for ASB surgery was osteoradionecrosis (ORN) of the NFO bony segment which was first detected at an average of 3.6 years (range: 2–32 years) postradiation therapy. High-risk patients for future ORN of the NFO segment (n = 3) were primarily reconstructed using a vascularized free flap. Nine patients had malignant disease, and four of them were alive without evidence of disease during the follow-up period (average, 48 months). Their QoL was comparable to that of patients who had undergone subcranial ASB resection without free flap reconstruction. Conclusions The ASB median free flap method of reconstruction is a safe and reliable in cases of large complex median ASB defects without orbital resection or maxillectomy. This approach is suitable for patients who had undergone previous surgery, radiotherapy and/or those who present with osteoradionecrosis, as well as for patients with high risk of NFO segment ORN.

Understanding the spectrum of paediatric mechanical finger and hand trauma seeking acute care

Purpose Paediatric hand injuries are a frequent reason for acute medical evaluation. Previous studies have reported only fracture rates, surgical injuries or are limited to database diagnosis coding. The average fracture rates and injury distributions across the hand for all mechanical injuries have not been well-described. Methods We performed a retrospective review of all emergent/urgent care visits over 18 months at a US paediatric tertiary hospital with hand injuries recorded anywhere in the encounter. Patient, injury and encounter details were recorded with additional imaging review, categorized and described. Results A total of 523 patient visits (0.64% of all encounters) were for mechanical hand trauma. The injury mechanism was 42% crush, 19% jammed, 12% impact, 12% fall on outstretched hand, 7% hyperextension and 8% other/unclear. Crush was responsible for 80% of injuries in patients aged 0 to six years old but only 17% in patients aged 13 to 18 years. Crush resulted in fractures only 26% of the time, while other mechanisms were more likely to fracture (33% to 87%). Border digits were injured more often than others (21% to 23% versus 13% to 17%), and were most commonly fractured in the proximal phalanx (57% to 67% versus 22% to 34% for non-border digits). Providers correctly coded for basic fracture presence in 89.1% of injuries, but 53% of codes were not finger or laterality-specific, and only 15% specified a bony segment demonstrating that International Classification of Diseases-9 coding was nonspecific for injury patterns. Conclusion Patients with paediatric hand injuries frequently utilize emergency care and understanding the basic patterns of injury can guide resource utilization and future studies on optimal treatment algorithms in this setting. Level of Evidence IV, Prognostic, Case Series

Soft Tissue Artifact Compensation Using Triangular Cosserat Point Elements (TCPEs)

Existing methods which compensate for the Soft Tissue Artifact (STA) in optoelectronic motion measurements estimate the rigid motion of a nearly rigid underlying body segment based on analysis of the motion of all fiducial markers. The objective of the proposed Triangular Cosserat Point Elements (TCPE) method is to estimate the motion of the underlying body segment even when the STA in the entire cluster of markers can be large. This is accomplished by characterizing the cluster of markers with TCPEs defined by triangles based on all combinations of three markers. Then, scalar deformation measures characterizing the magnitudes of strain and relative rotation of pairs of TCPEs are defined for each TCPE. These deformation measures are used to define a filtered group of TCPEs which best represents the motion of the underlying body segment. The method was tested using an experimental setup that consists of a rigid pendulum with a deformable 300ml silicone breast implant attached to it as a simulation of the soft tissue around a bony segment. The rotation angles extracted from markers on the deformable implant were compared with simultaneous measurements of the rigid pendulum using an optoelectronic system. Analysis of the experimental data shows that this filtering process substantially reduces the error due to the STA even though the data set includes large deformations. In particular, the analysis shows that the error reduction using the TCPE approach is larger than the reductions obtained using standard least-squares minimization methods.

The impact of transferred vascularized toe joint length on motion arc of reconstructed finger proximal interphalangeal joints: a cadaveric study

Vascularized toe joint transfer for finger proximal interphalangeal joint reconstruction can result in sub-optimal arc of motion and extension lag due to inappropriate intercalated bony segment length. We investigated the impact of intercalated segment length on passive arc of motion and extension lag of the reconstructed proximal interphalangeal joint. Cadaveric intercalated joint grafts were harvested from lesser toes and transferred to cadaveric fingers. The pre-determined finger proximal interphalangeal joint defect size was 2 cm. Three different intercalated segment lengths were inserted and resulting proximal interphalangeal joint arc of motion and extension lag were measured. The average arc of motion of finger proximal interphalangeal joints was 81° and 54° for toe proximal interphalangeal joints. Long intercalated segments had an average arc of motion of 30° with 32° extension lag. Equal-length intercalated segments had an average 49° arc of motion with 15° extension lag. Short intercalated segments had an average arc of motion of 71° with 8° extension lag. Shorter intercalated segments provide the greatest reduction in extension lag.

Evaluation of feasibility of preoperative concurrent chemoradiotherapy in locally advanced operable oral cancer and resection and reconstruction of mandibular/maxillary segment with prefabricated free fibular graft.

e17558 Background: Every year more than 500,000 patients are diagnosed with oral cancer worldwide and majority require surgery and radiotherapy as a definitive curative treatment. Loss of bony segment of mandibular/maxillary bone with resultant loss of shape, function and ability to chew the food is known. Neoadjuvant chemoradiotherapy is known to have improved disease outcomes in many solid tumours. Methods: Total Seven patients underwent the planned protocol of 100 days. All patients were male and median age was 46 years. Six patients had disease involving lower alveolus and one had upper alveolus. All had no palpable nodes clinically. Step 1 a. Neoadjuvant treatment of Radiotherapy to Primary disease and draining lymph nodes dose of 45 to 50 Gy in 25 fractions over 5 weeks along with concurrent weekly Cisplatin 40mg/m2 for 5 cycles b. Mock surgery on 3D models with defining of insertion site of implants on fibular segment. Step 2 Insertion of dental implants in fibula and split skin graft in the desired fibular site in second week of radiotherapy. Step 3 Definitive surgery 6 weeks after completion of chemoradiotherapy and reconstruction by free fibular segment with primary dental prosthesis checking occlusion of oral bite. Results: Six patients(85.7%) are alive and free of disease at median follow up of 6.7 months. Three(42.8%) patients underwent prosthetic placement with acceptable outcome. Two patients had trismus and undergoing oral physiotherapy. Six patients had orocutaneous fistula. One had extrusion of fibular graft and one patient died. Five(71.4%) patients had complete response on final histopathology report and two had partial response. Conclusions: : A novel technique for better functional and aesthetic results with possible improved survival in operable oral cancer. Future randomized studies are needed for validation.

Syringocystadenoma Papilliferum of the Bony External Auditory Canal: A Rare Tumor in a Rare Location

Tumors originating from ceruminous glands are rare lesions of the external auditory canal. The lack of specific clinical and radiological signs makes their diagnosis challenging. We report the case of an exceptionally rare benign tumor, a syringocystadenoma papilliferum (SCAP), in an atypical location in the bony segment of the external auditory canal with uncommon clinical signs. The special traits of the case included the following: the most lateral component of the tumor was macroscopically cystic and a granular myringitis with an obstructing keratin mass plug was observed behind the mass. The clinical, audiological, radiological, and histological characteristics of the neoplasm are consequently presented. Intraoperative diagnosis of the epidermal cyst was proposed. The final diagnosis of SCAP was determined only by histological analysis after the surgical excision. The educational aspects of the case are critically discussed.