Mandibular Fracture in Conjunction with Bicortical Penetration, Using Wide-Diameter Endosseous Dental Implants

Prosthodontic rehabilitation of a patient with an atrophic edentulous mandible presents a significant challenge in restoring esthetics and function. The purpose of this clinical report is to describe fracture of an atrophic edentulous mandible opposing maxillary natural dentition in association with endosseous dental implants. The patient received two wide-diameter implants in the anterior mandible for an implant-assisted mandibular overdenture, in which the implants penetrated the inferior border of the mandible for bicortical stabilization. Three months following implant placement surgery, the patient experienced pain, swelling, and intraoral purulent drainage around the right implant. Panoramic radiograph revealed a fracture of the mandible through the right implant site and signs of infection around the left implant. The implants were removed surgically, and open reduction and fixation of the fracture site were undertaken using a titanium bone fixation plate. This clinical report demonstrates that placement of wide-diameter implants in conjunction with bicortical penetration in a severely atrophic edentulous mandible can risk fracture of the mandible.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79058/1/j.1532-849X.2010.00646.x.pd

Posterior Cervical Spine Crisscross Fixation: Biomechanical Evaluation

Background Biomechanical/anatomic limitations may limit the successful implantation, maintenance, and risk acceptance of posterior cervical plate/rod fixation for one stage decompression-fusion. A method of posterior fixation (crisscross) that resolves biomechanical deficiencies of previous facet wiring techniques and not reliant upon screw implantation has been devised. The biomechanical performance of the new method of facet fixation was compared to the traditional lateral mass plate/screw fixation method. Methods Thirteen human cadaver spine segments (C2-T1) were tested under flexion-compression loading and four were evaluated additionally under pure-moment load. Preparations were evaluated in a sequence of surgical alterations with intact, laminectomy, lateral mass plate/screw fixation, and crisscross facet fixation using forces, displacements and kinematics. Findings Combined loading demonstrated significantly lower bending stiffness (p \u3c 0.05) between laminectomy compared to crisscross and lateral mass plate/screw preparations. Crisscross fixation showed a comparative tendency for increased stiffness. The increased overall motion induced by laminectomy was resolved by both fixation techniques, with crisscross fixation demonstrating a comparatively more uniform change in segmental motions. Interpretation The crisscross technique of facet fixation offers immediate mechanical stability with resolution of increased flexural rotations induced by multi-level laminectomy. Many of the anatomic limitations and potentially deleterious variables that may be associated with multi-level screw fixation are not associated with facet wire passage, and the subsequent fixation using a pattern of wire connection crossing each facet joint exhibits a comparatively more uniform load distribution. Crisscross wire fixation is a valuable addition to the surgical armamentarium for extensive posterior cervical single-stage decompression-fixation

Accuracy of end-on fluoroscopy in predicting implant position in relation to the vertebral canal in dogs.

Objective To evaluate the accuracy of end-on fluoroscopy in predicting implant position in relation to the vertebral canal in the canine thoracolumbar vertebral column. Study design In vitro imaging and anatomic study. Animals Canine cadaveric thoracolumbar vertebral columns (n = 5). Methods Smooth Steinmann pins were inserted bicortically into the thoracolumbar vertebral columns between T10 and L7 using recommended insertion angles. Penetration of the spinal canal was not strictly avoided. After pin placement, end-on fluoroscopy images were obtained of each pin. Pin position was subsequently assessed by four evaluators and determined to either being out of the vertebral canal or in, with the latter being additionally divided into partially or completely penetrating the canal. To assess potential differences in modalities, fluoroscopy images were gray-scale inverted and evaluated again later by the same four individuals. Correct identification of pin position in relationship to the vertebral canal was assessed for both fluoroscopy images. Anatomic preparation of the spines was used for verification of pin position in relation to the spinal canal. Some data from this study were compared with historical data on accuracy using orthogonal radiography and computed tomography (CT). Results Overall sensitivity and specificity of F to detect vertebral canal penetration was 98.8 % (95% confidence interval (CI), 96.0-99.6) and 98.0% (95% CI, 77.0-99.9), respectively. For Fi, sensitivity and specificity were 97.0% (95% CI, 91.5-99.0) and 98.5% (95% CI, 81.5-99.9) respectively. F exceeded Fi for the sensitivity of detecting pin penetration into the vertebral canal (p = 0.039) but specificities were not different (p = 0.585). When comparing to historical data, the overall accuracy of end-on fluoroscopy (F) and inverted fluoroscopy (Fi) was statistical better than conventional radiographic assessment (p < 0.001). Conclusion End-on fluoroscopy is a highly accurate method for the assessment of pin position in relationship to the thoracolumbar spinal canal in cadaveric dogs. Clinical significance End-on fluoroscopy, with or without inversion, is accurate in identifying vertebral canal violation by bicortically placed Steinmann pins. When CT is not available, end-on fluoroscopy might be a valuable imaging modality to determine pin position in the canine vertebral column

Distal normograde intramedullary pin and locking plate placement in the canine humerus: A cadaveric study

Objective: To identify a repeatable anatomic landmark for pin insertion and to describe the technique for placement of a distal normograde intramedullary (IM) pin of approximately 35% of the IM diameter using this approach combined with a locking compression plate (LCP) on the medial aspect of the canine humerus. Study Design: Ex vivo anatomic study. Sample Population: Canine cadavers (n=10 Greyhounds). Methods: An anatomic landmark for pin insertion was identified based on three-dimensional reconstructions of previous elbow computed tomography studies and cadaveric dissection of the medial aspect of the humeral condyle. Bilateral distal normograde IM pin and LCP placement were performed and confirmed radiographically and by disarticulation and sagittal sectioning. Results: The anatomic landmark for pin insertion was consistently identified in each specimen using the technique described. Distal normograde insertion of a 3.5 mm IM pin was possible in Greyhound cadaveric humeri at the described location in conjunction with a 3.5 mm LCP with fixed angle, locked screws. A monocortical locking screw was required to avoid interference with the IM pin in 28 of 60 of the 3 proximal screw holes. No pin interference was encountered in any of the distal screw holes. Conclusion: The anatomic landmark and technique described in our study enabled repeatable successful placement of a distal normograde IM pin of approximately 35% of the IM diameter combined with an LCP on the medial aspect of the canine humerus. This technique may be useful for locking plate-rod fixation of distal humeral diaphyseal fractures

Improving accuracy of the intermediate splint in substantial intermaxillary sagittal discrepancies using an extra anterior anchorage point:technical note

To describe a technical feature that increases the stability of the intermediate splint in patients where bimaxillary surgery with great maxillary/mandibular advancements are planned. Prospective evaluation of the intermediate splint dental vertical penetration in patients undergoing bimaxillary surgery where great sagittal discrepancy occur in the anterior sector between the upper and lower jaws when the intermediate splint is placed by adding an extra intermaxillary fixation (IMF) screw (2x9 mm) placed between the central incisors of the maxilla and fixed to the most anterior aspect of the intermediate splint following the direction of the sagittal maxillo-mandibular discrepancy from January to September 2018. The postoperative evaluation comparing the accuracy of conventional fixation versus fixation with an extra anterior anchorage point through photographic assessment and intraoral digital scanner demonstrated better dental penetration, and therefore improved intermediate splint precision with the latter in all cases Our results suggest that this is a simple and safe technique that can be easily reproduced and optimizes the outcomes by increasing the accuracy of translation of the planned surgical movements to the operating room

Tibial stress fracture after computer-navigated total knee arthroplasty

A correct alignment of the tibial and femoral component is one of the most important factors determining favourable long-term results of a total knee arthroplasty (TKA). The accuracy provided by the use of the computer navigation systems has been widely described in the literature so that their use has become increasingly popular in recent years; however, unpredictable complications, such as displaced or stress femoral or tibial fractures, have been reported to occur a few weeks after the operation. We present a case of a stress tibial fracture that occurred after a TKA performed with the use of a computer navigation system. The stress fracture, which eventually healed without further complications, occurred at one of the pinhole sites used for the placement of the tibial trackers

Pathological mandibular fracture: a severe complication of periimplantitis

Nowadays, dental implant treatment is a very common option for patients even in medical compromised conditions. Some complications related to them have been described. Periimplantitis (PI) is one of the biggest concerns of these kind of treatments, probably has a multifactorial aethiology. Usually the consequences of PI are the loss of the implants and prostheses, expenses of money and time for dentists and patients. Very often PI implies the necesity of repeating the treatment . Pathological mandibular fracture due to PI is a severe but infrequent complication after dental implant treatment, especially after PI. In this study we present three cases of mandibular pathologic fractures among patients with different medical and dental records but similar management: two of them had been treated years ago of oral squamous cell carcinoma with surgery and radiotherapy, the other patient received oral bisphosphonates for osteoporosis some years after implantation. We analized the causes, consequences and posible prevention of these fractures as well as the special features of this kind of mandibular fractures and the different existing treatments