Robinson, Dale;Aguilar, Luis;Gatti, Andrea;Abduo, Jaafar;Lee, Peter Vee Sin;Ackland, David
The Journal of Advanced Prosthodontics
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v.11
no.3
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pp.169-178
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2019
PURPOSE. While dental implants have displayed high success rates, poor mechanical fixation is a common complication, and their biomechanical response to occlusal loading remains poorly understood. This study aimed to develop and validate a computational model of a natural first premolar and a dental implant with matching crown morphology, and quantify their mechanical response to loading at the occlusal surface. MATERIALS AND METHODS. A finite-element model of the stomatognathic system comprising the mandible, first premolar and periodontal ligament (PDL) was developed based on a natural human tooth, and a model of a dental implant of identical occlusal geometry was also created. Occlusal loading was simulated using point forces applied at seven landmarks on each crown. Model predictions were validated using strain gauge measurements acquired during loading of matched physical models of the tooth and implant assemblies. RESULTS. For the natural tooth, the maximum vonMises stress (6.4 MPa) and maximal principal strains at the mandible ($1.8m{\varepsilon}$, $-1.7m{\varepsilon}$) were lower than those observed at the prosthetic tooth (12.5 MPa, $3.2m{\varepsilon}$, and $-4.4m{\varepsilon}$, respectively). As occlusal load was applied more bucally relative to the tooth central axis, stress and strain magnitudes increased. CONCLUSION. Occlusal loading of the natural tooth results in lower stress-strain magnitudes in the underlying alveolar bone than those associated with a dental implant of matched occlusal anatomy. The PDL may function to mitigate axial and bending stress intensities resulting from off-centered occlusal loads. The findings may be useful in dental implant design, restoration material selection, and surgical planning.
Celiac artery compression is a rare condition in which the celiac artery is compressed by the median arcuate ligament. Case reports of compression after trauma are hard to find. Blunt traumatic pericardium rupture is also a rare condition. We report a single patient who experienced both rare conditions from a single blunt injury. An 18-year-old woman was brought to the trauma center after a fatal motorcycle accident, in which she was a passenger. The driver was found dead. Her vital signs were stable, but she complained of mild abdominal pain, chest wall pain, and severe back pain. There were no definite neurologic deficits. Her initial computed tomography (CT) scan revealed multiple rib fractures, moderate lung contusions with hemothorax, moderate liver injury, and severe lumbar spine fracture and dislocation. She was brought to the angiography room to check for active bleeding in the liver, which was not apparent. However, the guide wire was not able to pass through the celiac trunk. A review of the initial CT revealed kinking of the celiac trunk, which was assumed to be due to altered anatomy of the median arcuate ligament caused by spine fractures. Immediate fixation of the vertebrae was performed. During recovery, her hemothorax remained loculated. Suspecting empyema, thoracotomy was performed at 3 weeks after admission, revealing organized hematoma without pus formation, as well as rupture of the pericardium, which was immediately sutured, and decortication was carried out. Five weeks after admission, she had recovered without complications and was discharged home.
Recently, a variety of arthroscopic techniques have been reported for the treatment of the displaced tibial eminence fracture. The purpose of this study was to describe details of arthroscopic technique using pull-out wire and to evaluate the results. Eleven patients with irreducible type II and type III tibial eminence fractures underwent the arthroscopic reduction and internal fixation using double strand pull-out wiring. The anterior cruciate ligament tibial drill guide was utilized for the reduction of fracture and passage of the guide pins. The tibial eminence fracture was firmly fixed with double strand 26-gauge pull-out wire(0.45mm diameter). Fracture union was achieved at 7.2 weeks (range, six to eight weeks) after operation. All cases were united at the last follow-up. Subjectively, nine patients had no pain and no restriction of daily activities. Two patients with combined injuries had limitation of knee motion(10 to 130 degrees, respectively) and one patient showed mild anterior laxity. Early rehabilitation was enabled without loss of reduction and breakage of pull-out wire. The arthroscopic reduction and internal fixation using pull-out wire showed good results including early rehabilitation, early fracture union, minimal morbidity, and no requirement of the second operation for hard ware removal.
The distinction between isolated and combined injuries is crucial both for treatment and prognosis. For most combined injuries, surgical treatment continues to be favored over nonoperative treatment. It is generally agreed that isolatel PCL injuries do well without surgery. There has been an interest by many authors to fix the graft directly to the posterior aspect of the tibia(tibial inlay). With this procedure, tibial graft fixation will be more direct and theoretically reduce the bending effects of the graft with a fixation site far away from the tibial insertion. Modified tibial inlay technique, which is the posterior approach does not require the patient to be in the prone or lateral decubitus position during the operation. Use of a double-bundle reconstructive technique is attractive and has been performed by some surgeons. At this time, this procedure is still being investigated and should not be routinely used in the clinical setting until studies have indicated an advantage over current single-bundle techniques. However theologically, double-bundle reconstructive technique is more useful in severe posterior unstable knee. Recent advances have increased our knowledge of the anatomy and mechanical characteristics of the PCL. Basic science research has further increased our awareness of the interaction of the posterolateral structures with the PCL. To achieve restoration of normal posterior laxity, it is critical to address the posterior as well as the postero-lateral structures. Surgical treatment is often complex and requires a wide range of surgical techniques and skills to treat associated injuries. When the PCL is reconstructed, most surgeons choose to reconstruct the anterolateral component using a graft of sufficient size and strength. The initial postoperative rehabilitation should be addressed cautiously in an effort to avoid excessive forces on delicate repairs and reconstructions in these complex injuries. Further research is necessary to evaluate new surgical approaches such as double-bundle reconstructions and tibial inlay techniques as well as improved techniques for capsular and collateral ligament injuries.
Chun Churl-Hong;Lee Seong-Ho;Lee Byung-Chang;Cho Yong-Woo
Clinics in Shoulder and Elbow
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v.1
no.2
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pp.180-185
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1998
There has been considerable controversy as to the treatment method of dislocation of the acromioclavicular joint, so various operative treatment modalities have been suggested. We analyzed the results of 40 patients with acromioclavicular dislocation, in whom twenty patients were treated by modified Phemister method and 20 patients by modified Weaver-Dunn method above follow-up two years. The purpose of this study was to compare the clinical results of two operative methods. According to Weitzman criteriae for clinical results, 12 cases were excellent, six cases good and two cases fair in modified Phemister method. But in modified Weaver-Dunn method, ten cases were excellent, eight cases good, one case fair and one case poor. In radiological result, coracoclavicular distance was measured at preoperative, postoperative and last follow-up period. The modified Phemister method was 6.lmm, 1.5mm and 2.4mm respectively, and the modified Weaver-Dunn method 7.8mm, 2.lmm and 2.5mm respectively. The complications were two cases of heterotopic ossification, one case of inadequate fixation and one case of K-wire breakage in modified Phemister method, and two cases of early fixation loss and one case of heterotopic ossification in modified Weaver-Dunn method. We obtained that the clinical, functional and radiological results showed no significant difference in two methods. The modified Phemister method was effective treatment for old patients in acute injuries due to short operation time and simple technique. The modified Weaver-Dunn method, as a reconstructive operation that reduces various complications for young and active male patients, was also good for getting the stability of coracoclavicular ligament through clavicular bony union.
Yang, Hee Seok;Kim, Jeong Woo;Lee, Sung Hyun;Yoo, Byung Min
Clinics in Shoulder and Elbow
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v.21
no.4
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pp.234-239
/
2018
Background: In elbow fracture-dislocation, partial excision of the comminuted radial head fracture that is not amenable to fixation remains controversial considering the accompanying symptoms. This study was undertaken to evaluate the results of radial head partial excision when the comminuted radial head fracture involved <50% of the articular surface in all-arthroscopic repair of elbow fracture-dislocation. Methods: Patients were divided into two groups based on the condition of the radial head fracture. In Group A, the patients had a radial head comminuted fracture involving <50% of the articular surface, and underwent arthroscopic partial excision. Group B was the non-excision group comprising patients with stable and non-displacement fractures. Follow-up consultations were conducted at 6 weeks and at 3, 6, 12, and 24 months after surgery. Results: In all, 19 patients (Group A: 11; Group B: 8) met the inclusion criteria and were enrolled in the study. At the final follow-up, all 19 patients showed complete resolution of elbow instability. No significant differences were observed in the range of motion, visual analogue scale score, and Mayo elbow performance score between groups. Radiological findings did not show any complications of the radiocapitellar joint. However, nonunion of the coracoid fracture was observed in 3 patients (Group A: 1; Group B: 2), without any accompanying instability and clinical symptoms. Conclusions: Considering that the final outcome is coronoid fracture fixation and lateral collateral ligament complex repair for restoring elbow stability, arthroscopic partial excision for radial head comminuted fractures involving <50% of articular surface is an effective and acceptable treatment for elbow fracture-dislocation.
Purpose: This study was performed to compare the strength of ligamentous attached sites of cadaveric distal femur and to obtain reliable biomechanical data to use in ligamentous reconstruction or augmentation. Materials and Methods: Fifteen cadaveric distal femurs were used for this study. After measuring the bone density, 5.0 mm cannulated screw (Experiment 1) or reconstructed porcine ligament (Experiment 2) was inserted into the each ligamentous attached sites of anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL) and lateral collateral ligament (LCL). In experiment 2, reconstructed porcine graft was fixed with bioabsorbable screw in ligamentous insertion sites. And we measured the maximal pullout force of each ligamentous attached sites of cadaveric distal femur. Results: Average bone mineral density was $1.205{\pm}0.137\;g/cm^2$ in experiment 1, $1.236{\pm}0.089\;g/cm^2$ in experiment 2, which showed no statistically significant differences. In experiment 1, average pull-out strength of ACL, PCL, MCL and LCL group were $519.1{\pm}111.7$ N, $638.9{\pm}144.4$ N, $169.7{\pm}56.0$ N, $225.6{\pm}61.5$ N respectively. In experiment 2, the average pull-out strength were $310.6{\pm}31.0$ N, $379.9{\pm}47.4$ N, $104.0{\pm}14.4$ N, $131.5{\pm}21.9$ N respectively. In experiment 1, there was no significant difference between ACL and PCL group and between MCL and LCL group. However, the maximal pullout strength of MCL and LCL group were significantly lower than that of ACL and PCL group (p<0.01). Experiment 2 showed the same results of experiment 1. Conclusion: Because stiffness of MCL and LCL attached sites are much lower than that of ACL and PCL attached sites, we may consider augmented fixation in ligamentous reconstructions of MCL and LCL.
Journal of the korean academy of Pediatric Dentistry
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v.21
no.2
/
pp.518-524
/
1994
A traumatically intruded tooth is one that is forcefully and abruptly dispaced from its position into the surrounding alveolar bone. Although intrusion of permanent teeth is infrequent, the sequelae compromise the longevity of the tooth and often include pulp necrosis, internal and external root resorption, rupture of periodontal ligament and loss of marginal bone. The purpose of this study was to examine three common management techniques for traumatic intrusion, observation for re-eruption, surgical repositioning & fixation and orthodontic extrusion. In the recent, the accepted treatment was to allow the permanent teeth to reerupt spontaneously for 6-8 weeks. If this did not occur, orthodontic traction was applied. The pulpal status of the teeth was monitored and either calcium hydroxide therapy or conventional endodontics was instituted following pulpal necrosis depending on the maturity of the root end. Pulpectomy and a calcium hydroxide filling were also the treatment of choice if there was evidence of internal or external root resorption. This will reduce the chance of root resorption and provide a period of monitoring prior to a definitive root canal filling.
The authors report a case of epidural and extraforaminal calcification caused by repetitive triamcinolone acetonide injections. A 66-year-old woman was admitted presenting with lower extremity weakness and radiating pain in her left leg. Ten months before admission, the patient was diagnosed as having an L4-5 spinal stenosis and underwent anterior lumbar interbody fusion followed by posterior fixation. Her symptoms had been sustained and she did not respond to transforaminal steroid injections. Repetitive injections (10 times) had been performed on the L4-5 level for six months. She had been taking bisphosphonate as an antiresorptive agent for ten months after surgery. Calcification in the ventral epidural and extraforaminal space was detected. The gritty particles were removed during decompressive surgery and these were proven to be a dystrophic calcification. The patient recovered from weakness and radiating leg pain. Repetitive triamcinolone acetonide injections after discectomy may be the cause of dystrophic calcification not only in the degenerated residual disc, but also in the posterior longitudinal ligament. Possible mechanisms may include the toxicity of preservatives and the insolubility of triamcinolone acetonide. We should consider that repetitive triamcinolone injections in the postdisectomy state may cause intraspinal ossification and calcification.
Vargas, Daniel Gaitan;Woodcock, Santiago;Porto, Guido Fierro;Gonzalez, Juan Carlos
Clinics in Shoulder and Elbow
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v.23
no.1
/
pp.27-30
/
2020
Osborne-Cotterill lesion is an osteochondral fracture located in the posterolateral margin of the humeral capitellum, which may be associated with a defect of the radial head after an elbow dislocation. This lesion causes instability by affecting the lateral ulnar collateral ligament over its capitellar insertion, which is associated with a residual capsular laxity, thereby leading to poor coverage of the radial head, and hence resulting in frequent dislocations. We present a 54-year-old patient, a physician who underwent trauma of the left elbow after falling from a bike and suffered a posterior dislocation fracture of the elbow. The patient subsequently presented episodes of instability, and additional work-up studies diagnosed the occurrence of Osborne-Cotterill lesion. An open reduction and internal fixation of the bony lesion was performed, with reinsertion of the lateral ligamentous complex. Three months after surgery, the patient was asymptomatic, having a flexion of 130° and extension of 0°, and resumed his daily activities without any limitation. Currently, the patient remains asymptomatic 2 years after the procedure. Elbow instability includes a large spectrum of pathological conditions that affect the biomechanics of the joint. The Osborne-Cotterill lesion is one among these conditions. It is a pathology that is often forgotten and easily overlooked. Undoubtedly, this lesion requires surgical intervention.
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