Coronectomy of deeply impacted lower third molar : incidence of outcomes and complications after one year follow-up

Objectives: The purpose of present study was to assess the surgical management of impacted third molar with proximity to the inferior alveolar nerve and complications associated with coronectomy in a series of patients undergoing third molar surgery. Material and Methods: The position of the mandibular canal in relation to the mandibular third molar region and mandibular foramen in the front part of the mandible (i.e., third molar in close proximity to the inferior alveolar nerve [IAN] or not) was identified on panoramic radiographs of patients scheduled for third molar extraction. Results: Close proximity to the IAN was observed in 64 patients (35 females, 29 males) with an impacted mandibular third molar. Coronectomy was performed in these patients. The most common complication was tooth migration away from the mandibular canal (n = 14), followed by root exposure (n = 5). Re-operation to remove the root was performed in cases with periapical infection and root exposure. Conclusions: The results indicate that coronectomy can be considered a reasonable and safe treatment alternative for patients who demonstrate elevated risk for injury to the inferior alveolar nerve with removal of the third molars. Coronectomy did not increase the incidence of damage to the inferior alveolar nerve and would be safer than complete extraction in situations in which the root of the mandibular third molar overlaps or is in close proximity to the mandibular canal

Treatment response using CT-based rigidity analysis in an animal model of lytic musculoskeletal lesions subjected to systemic therapy

Cancer is a global epidemic; over 1.5 million new cancer diagnoses and greater than 600,000 deaths due to cancer are estimated to occur in the United States within the year 2015 alone. Approximately two-thirds of patients with bone metastases will experience pain, pathological fractures, spinal cord or nerve root compression, paralysis, impaired mobility, bone marrow infiltration and hypercalcemia of malignancy. We induced bone metastases through inoculation of rat femurs with MDA-MB-231 human breast cancer cells in order to compare the effectiveness of various treatment modalities, disease progression and recovery through the use of imaging methods in current clinical practice. CTRA provides highly accurate monitoring of metastases progression and treatment through both Ibandronate and Paclitaxel therapies. Using computed tomography (QCT)-based analysis to calculate the load bearing capacity of bone infiltrated with metastatic breast carcinoma, fracture risk threshold was predicted using Computed Topography Rigidity Analysis (CTRA) with 100% sensitivity and 90% specificity. The results of this study further validate that there is an existing gap between clinical guidelines and physician’s recommendations. This inconsistency necessitates that the decision making process for the selection of surgical or non-surgical treatment must be narrowed by more advanced prognostic tools such as CTRA

Clinical observation of diminished bone quality and quantity through longitudinal HR-pQCT-derived remodeling and mechanoregulation.

High resolution peripheral quantitative computed tomography (HR-pQCT) provides methods for quantifying volumetric bone mineral density and microarchitecture necessary for early diagnosis of bone disease. When combined with a longitudinal imaging protocol and finite element analysis, HR-pQCT can be used to assess bone formation and resorption (i.e., remodeling) and the relationship between this remodeling and mechanical loading (i.e., mechanoregulation) at the tissue level. Herein, 25 patients with a contralateral distal radius fracture were imaged with HR-pQCT at baseline and 9-12 months follow-up: 16 patients were prescribed vitamin D3 with/without calcium supplement based on a blood biomarker measures of bone metabolism and dual-energy X-ray absorptiometry image-based measures of normative bone quantity which indicated diminishing (n = 9) or poor (n = 7) bone quantity and 9 were not. To evaluate the sensitivity of this imaging protocol to microstructural changes, HR-pQCT images were registered for quantification of bone remodeling and image-based micro-finite element analysis was then used to predict local bone strains and derive rules for mechanoregulation. Remodeling volume fractions were predicted by both average values of trabecular and cortical thickness and bone mineral density (R2 > 0.8), whereas mechanoregulation was affected by dominance of the arm and group classification (p < 0.05). Overall, longitudinal, extended HR-pQCT analysis enabled the identification of changes in bone quantity and quality too subtle for traditional measures

Experimental and numerical investigations of bone drilling for the indication of bone quality during orthopaedic surgery

Bone drilling is an essential part of many orthopaedic surgical procedures, including those for internal fixation and for attaching prosthetics. Drilling into bone is a fundamental skill that can be both very simple, such as drilling through long bones, or very difficult, such as drilling through the vertebral pedicles where incorrectly drilled holes can result in nerve damage, vascular damage or fractured pedicles. Also large forces experienced during bone drilling may promote crack formation and can result in drill overrun, causing considerable damage to surrounding tissues. Therefore, it is important to understand the effect of bone material quality on the bone drilling forces to select favourable drilling conditions, and improve orthopaedic procedures. [Continues.

Phase-field boundary conditions for the voxel finite cell method: surface-free stress analysis of CT-based bone structures

The voxel finite cell method employs unfitted finite element meshes and voxel quadrature rules to seamlessly transfer CT data into patient-specific bone discretizations. The method, however, still requires the explicit parametrization of boundary surfaces to impose traction and displacement boundary conditions, which constitutes a potential roadblock to automation. We explore a phase-field based formulation for imposing traction and displacement constraints in a diffuse sense. Its essential component is a diffuse geometry model generated from metastable phase-field solutions of the Allen-Cahn problem that assumes the imaging data as initial condition. Phase-field approximations of the boundary and its gradient are then employed to transfer all boundary terms in the variational formulation into volumetric terms. We show that in the context of the voxel finite cell method, diffuse boundary conditions achieve the same accuracy as boundary conditions defined over explicit sharp surfaces, if the inherent length scales, i.e., the interface width of the phase-field, the voxel spacing and the mesh size, are properly related. We demonstrate the flexibility of the new method by analyzing stresses in a human femur and a vertebral body

In silico methods to evaluate Fracture Risk and Bone Mineral Density changes in patients undergoing Total Hip Replacement

La sostituzione totale d’anca è uno degli interventi chirurgici con le più alte percentuali di successo. Esistono due varianti di protesi d’anca che differiscono in base al metodo di ancoraggio all’osso: cementate (fissaggio tramite cemento osseo) e non cementate (fissaggio tramite forzamento). Ad oggi, i chirurghi non hanno indicazioni quantitative di supporto per la scelta fra le due tipologie di impianto, decidendo solo in base alla loro esperienza. Due delle problematiche che interessano le protesi non cementate sono la possibilità di frattura intra-operatoria durante l’inserimento forzato e il riassorbimento osseo nel periodo di tempo successivo all’intervento. A partire da rilevazioni densitometriche effettuate su immagini da TC di pazienti sottoposti a protesi d’anca non cementata, sono stati sviluppati due metodi: 1) per la valutazione del rischio di frattura intra-operatorio tramite analisi agli elementi finiti; 2) per la valutazione della variazione di densità minerale ossea (tridimensionalmente attorno alla protesi) dopo un anno dall’operazione. Un campione di 5 pazienti è stato selezionato per testare le procedure. Ciascuno dei pazienti è stato scansionato tramite TC in tre momenti differenti: una acquisita prima dell’operazione (pre-op), le altre due acquisite 24 ore (post 24h) e 1 anno dopo l’operazione (post 1y). I risultati ottenuti hanno confermato la fattibilità di entrambi i metodi, riuscendo inoltre a distinguere e a quantificare delle differenze fra i vari pazienti. La fattibilità di entrambe le metodologie suggerisce la loro possibilità di impiego in ambito clinico: 1) conoscere la stima del rischio di frattura intra-operatorio può servire come strumento di guida per il chirurgo nella scelta dell’impianto protesico ottimale; 2) conoscere la variazione di densità minerale ossea dopo un anno dall’operazione può essere utilizzato come strumento di monitoraggio post-operatorio del paziente

Non-invasive assessment of cartilaginous tissues in small animal models of injury and disease

Cartilage is a tissue that is critical for skeletal function, yet its study has been limited by a lack of quantitative, non-destructive, three-dimensional imaging techniques that enable simultaneous interrogation of both bone and cartilage. Recently, methods of contrast-enhanced micro-computed tomography (CECT) have been developed that exploit the electrostatic interactions between ionic contrast agents and negatively charged glycosaminoglycans (GAGs) in cartilage, thus providing information about the composition and morphology of cartilage that was previously only available via destructive methods. The goal of this dissertation project was to apply CECT, a non-destructive, three-dimensional imaging method, to understand the how the morphology and composition of cartilage changes in response to injury and disease. First, CECT was applied to a model of growth plate injury to quantify changes to the cartilaginous tissue of the growth plate and formation of bone bridges within this tissue in response to injury. Using CECT, it was possible to identify increased thickness and CECT attenuation at the injury site. This result, paired with histological evidence of localized dysregulation of cellular activity, suggests that treatment designed to reduce bone bridge formation at the injury site should also consider the effects of the treatment on the adjacent cartilage. Second, CECT was applied to a collagen antibody-induced arthritis (CAIA) model to determine the role of the A2B adenosine receptor (A2BAR) in the arthritic deterioration of bone and cartilage. CECT scans demonstrated that loss of GAG in the cartilage preceded degeneration, but that ablation of the A2BAR in mice had little effect on the degenerative changes in bone and cartilage associated with CAIA. These results suggest that the A2BAR does not independently mediate these changes and that it may be necessary to target multiple adenosine receptors. Third, the ability of CECT to monitor the fracture healing and predict the stiffness of the cartilaginous fracture callus was assessed both at the level of the whole callus and at the level of the cartilage tissue. Callus stiffness was negatively correlated with the size of the callus and the amount of cartilage, while neither stiffness nor indentation modulus were correlated with CECT attenuation, suggesting that the stiffness of the cartilaginous fracture callus depends on the amount, rather than GAG content of cartilage. The work presented in this dissertation provides outlines changes in both bone and cartilage that occur in pathological conditions and provides new insights for both the treatment and assessment of these conditions

Towards an app to estimate patient-specific perioperative femur fracture risk

To access publisher's full text version of this article click on the hyperlink belowTotal Hip Arthroplasty is one of the most successful surgery. However, due to the worldwide growing population life expectancy and the related incidence of age-dependent bone diseases, a growing number of cases of intra-operative fractures lead to revision surgery with high rates of morbidity and mortality. Surgeons choose the type of the implant, either cemented or cementless prosthesis, on the basis of the age, the quality of the bone and the general medical conditions of the patients. Generally, no quantitative measures are available to assess the intra-operative fracture risk. Consequently, the decision-making process is mainly based on medical operators’ expertise and qualitative information obtained by imaging. Motivated by this scenario, we here propose a mechanical-supported strategy to assist surgeons in their decisions, by giving intelligible maps of the risk fracture which take into account the interplay between actual strength distribution inside the bone tissue and its response to the forces exerted by the implant. To this end, we produce charts and patient-specific synthetic “traffic-light” indicators of fracture risk, by making use of ad hoc analytical solutions to predict the stress levels in the bone by means of CT-based mechanical and geometrical parameters of the patient. We felt that, if implemented in a friendly software or proposed as an app, the strategy could constitute a practical tool to help the medical decision-making process, in particular with respect to the choice of adopting cemented or cementless implantUniversita degli Studi della Campania "L.Vanvitelli", grant Programma VALERE: "VAnviteLli pEr la RicErca", DD