Surgical Stability Research Articles

Avaliação da alteração do plano oclusal em cirurgias ortognáticas combinadas com utilização de fixação interna rígida em pacientes com padrão facial de Classe II

OBJETIVO: avaliar a estabilidade de cirurgias bimaxilares com fixação interna rígida, na qual promoveu-se uma rotação anti-horária da mandíbula e conseqüente redução do ângulo do plano oclusal. METODOLOGIA: foram estudados 15 pacientes com padrão facial de Classe II e deficiência mandibular. Os movimentos cirúrgicos foram avaliados por meio de medidas lineares e angulares realizadas no programa CefX, obtidas de telerradiografias cefalométricas em norma lateral em três diferentes tempos: (T0) pré-operatório, (T1) pós-operatório imediato e (T2) pós-operatório de no mínimo 6 meses. RESULTADOS E CONCLUSÕES: os resultados demonstraram que a cirurgia bimaxilar promove mudanças faciais significativas e, principalmente, que a rotação anti-horária da mandíbula com redução do ângulo do plano oclusal mostrou-se estatisticamente estável, sendo uma opção confiável em cirurgias de pacientes com padrão facial de Classe II com deficiência mandibular.

Low-Profile Cortical Screw Tibial Fixation for Hamstring Anterior Cruciate Ligament Reconstruction: Surgical Technique and Stability Results

Tibial fixation is widely recognized to be the weak link in anterior cruciate ligament reconstruction. The soft cancellous bone poses challenges for intratunnel fixation, which has bred a variety of augmentations to this method. Cortical fixation is recognized as offering greater beneficial stiffness, but concerns about subcutaneous irritation of such devices has limited their use. We present a method of tibial fixation that uses a specially designed low-profile unicortical cancellous screw with a smooth shank just below the head as an anchor to whipstitches interwoven in the graft, which are then tied around the screw. This method was used in 153 consecutive knees, 139 of which were located for follow up 2 to 8 years after surgery. 86% had IKDC normal stability rates and 97% had 3 mm side-to-side KT 1000 differences. There were no graft failures and no clinically unstable knees. No cortical screw backed out, none were removed for symptoms, and all are still in place. There were no deep knee infections. A 1-inch long tibial incision was used. The screw is far enough from the knee that subsequent magnetic resonance images of the knee are not compromised.

Le Fort III Advancement Osteotomy in the Growing Child Affected by Crouzon's and Apert's Syndromes: Presurgical and Postsurgical Growth

This is a longitudinal cephalometric study of patients with craniofacial synostosis (Crouzon's and Apert's) syndromes who underwent Le Fort III advancement during early childhood. The objectives of the study were to quantify presurgical growth, surgical results, and surgical stability as well as long-term postsurgical growth. Of the 31 patients operated on during their growth period (less than 10 years of age), 17 had sufficient records to be included in the study: at infancy, before the Le Fort III osteotomy (average age=7.3 years, range: 4.8-10 years), and immediately after surgery. Ten of the patients were followed radiographically long term for an average of 6.1+/-2.7 years (range: 4.5-10.8 years). The presurgical abnormal midfacial vertical growth pattern was accurately described with a progressive class III discrepancy and an increasing exophthalmos. Remarkable postoperative stability of the maxillary segment was observed. After surgery, growth of the midface was measured, together with minimal, if any, anterior growth, similar to the presurgical growth pattern and rate. No actual detrimental or beneficial effect of surgery on subsequent growth was seen. This study quantitatively confirms that the standard Le Fort III osteotomy is a stable and effective but generally not definitive procedure in childhood. This study might also serve as a control sample to compare with groups of patients undergoing distraction osteogenesis to verify the actual advantages and shortcomings of this alternative technique.

HiRes 90K implantation using a minimally invasive surgical technique

This retrospective study compared safety and device outcomes for the HiRes 90K implant between (1) a minimally invasive (MI) surgical approach and early initial stimulation and (2) conventional surgical procedures and traditional initial programming schedules. Eight adults and 21 children were implanted using the MI approach and were programmed initially within 1 week after surgery. Surgical complications and device stability were compared to 55 adults and 16 children who were implanted using conventional surgery and programmed initially 4–6 weeks after surgery. No clinical differences were noted between patients undergoing MI surgery and patients implanted using more common surgical procedures. Electrode impedances stabilized earlier in the MI patients, and comfort levels for electrical stimulation were comparable between the two groups. Patients and families in the MI group have responded favorably to the shorter healing time, minimal hair shave, and shorter wait until initial programming.

Biomechanical evaluation of diagonal fixation in pedicle screw instrumentation.

Flexibility tests and finite element analyses were performed for the biomechanical evaluation of diagonal transfixation in pedicle screw instrumentation. To assess the biomechanical advantages of diagonal transfixation compared with conventional horizontal transfixation. A few pedicle screw instrumentation systems allow the use of cross-links in the diagonal direction. Such a diagonal transfixation is anticipated to improve the surgical construct stability, but its biomechanical qualities have not been completely evaluated. Flexibility tests were performed on 10 calf lumbar spines (L2-L5). Specimens were subjected to pure moments up to 8.2 Nm in flexion, extension, lateral bending, and extension while the resulting movements of L3 and L4 were measured by a three-dimensional motion analysis system. The tested cases included (1) intact, (2) pedicle screw fixation without transfixation after total removal of the L3-L4 disc, (3) pedicle screw fixation with diagonal transfixation, and (4) pedicle screw fixation with horizontal transfixation. Three-dimensional finite element models of the tested surgical constructs were also developed by use of three-dimensional beam elements to investigate the effect of diagonal transfixation and horizontal transfixation on the construct stability and the corresponding stress changes in the screws. When compared with no transfixation, horizontal transfixation significantly improved the lateral bending and axial rotation stability by 15.7% and 13.9%, respectively, but there was no improvement of stability in flexion and extension. By contrast, diagonal transfixation significantly improved the flexion and extension stability by 12% and 10.7%, respectively, but not the lateral bending and axial rotation stability in comparison with no transfixation. Comparison between horizontal transfixation and diagonal transfixation showed that the stabilizing effect of diagonal transfixation was greater in flexion and extension (13% and 11%, P < 0.01) than that of horizontal transfixation but smaller in lateral bending (11%, P < 0.05) and axial rotation (6.6%, P > 0.1). Finite element model predictions of the motion changes were similar to the changes observed in flexibility tests. In horizontal transfixation, the load changes, compared with no transfixion, were a 0.02% increase in flexion-extension, a 27.5% increase in lateral bending, and a 58% decrease in axial rotation, and the magnitudes of the moments applied on both the right and left pedicle screws were identical. However, when diagonal transfixation was achieved by connecting the left superior screw and the right inferior screw, the loads in the left screw were increased by 11.5% in flexion-extension, 43.6% in lateral bending, and 7.9% in axial rotation, whereas the loads in the right screw were decreased by 10.9% in flexion-extension, increased by 0.06% in lateral bending, and decreased by 18.1% in axial rotation. The results of this study showed that diagonal transfixation provides more rigid fixation in flexion and extension but less in lateral bending and axial rotation in comparison with horizontal transfixation. Furthermore, greater stresses in the pedicle screws were predicted in the diagonal transfixation model. These limitations of diagonal transfixation should be considered carefully for clinical application.

Computerized cephalometric evaluation of orthognathic surgical precision and stability in relation to maxillary superior repositioning combined with mandibular advancement or setback

Purpose A computerized, cephalometric, orthognathic surgical program (TIOPS) was applied in orthognathic surgical simulation, treatment planning, and postoperatively to assess precision and stability of bimaxillary orthognathic surgery. Patients and Methods Forty consecutive patients with dentofacial deformities requiring bimaxillary orthognathic surgery with maxillary superior repositioning combined with mandibular advancement or setback were included. All patients were managed with rigid internal fixation (RIF) of the maxilla and mandible and without maxillomandibular fixation (MMF). Preoperative cephalograms were analyzed and treatment plans produced by computerized surgical simulation. Planned, 5-week postoperative and 1-year postoperative maxillary and mandibular cephalometric positions were compared. Results In the mandibular advancement group, the anterior maxilla was placed too far superiorly, with an inaccuracy of 0.4 mm. The posterior maxilla and the anterior mandible were placed in the planned positions. The lower posterior part of the mandibular ramus was placed too far anteriorly, with an inaccuracy of 2.0 mm. However, the mandibular condyles were accurately placed. In the setback group, the anterior maxilla was placed too far superiorly and posteriorly, with a vertical and sagittal inaccuracy of 1.0 mm and 0.7 mm, respectively. The posterior part of the maxilla was placed in a posterior position with an inaccuracy of 1.9 mm. The anterior mandible was placed too far anteriorly with an inaccuracy of 0.9 mm. The lower posterior part of the mandibular ramus was placed in a posterior position with an inaccuracy of 0.9 mm. However, the mandibular condyles were accurately placed. The statistical analysis of the 1-year stability data showed that the maxilla had moved 0.3 mm posteriorly in the advancement group and the lower incisors had moved 0.8 mm superiorly. No other significant positional maxillary or mandibular changes were found. In the setback group, the maxilla had moved 0.5 mm posteriorly, the anterior mandible 0.5 mm anteriorly, and the lower incisors 0.7 mm superiorly. No significant positional changes were seen in the mandibular ramus. Conclusion The TIOPS computerized, cephalometric, orthognathic program is useful in orthognathic surgical simulation, planning, and prediction, and in postoperative evaluation of surgical precision and stability. The simulated treatment plan can be transferred to model surgery and finally to the orthognathic surgical procedures. The results show that this technique yields acceptable postoperative precision and stability.

Computerized cephalometric evaluation of orthognathic surgical precision and stability in relation to maxillary superior repositioning combined with mandibular advancement or setback

Computerized cephalometric evaluation of orthognathic surgical precision and stability in relation to maxillary superior repositioning combined with mandibular advancement or setback

Maxillomandibular advancement surgery in obstructive sleep apnea syndrome patients: Long-term surgical stability

Purpose: This study examined the long-term skeletal stability of relatively large maxillomandibular advancement surgery in the treatment of obstructive sleep apnea syndrome (OSAS). Materials and Methods: The presurgical, immediate (< 1 month), and longterm (>12 months) postsurgical cephalometric radiographs of 19 patients undergoing maxillomandibular advancement with simultaneous genioplasty for OSAS were studied. The cephalometric measurements and calculations were performed using a commercial cephalometric software. Results: Maxillary and mandibular advancement seems to be stable in the horizontal and vertical planes over the long term. There was no significant correlation between the amount of surgical advancement and the amount of postsurgical instability, with the exception of gonion in the vertical plane. Conclusion: The results from this study indicate that large surgical advancements in OSAS patients result in relatively stable repositioning of the maxilla and mandible over the long term.

Maxillomandibular advancement surgery in obstructive sleep apnea syndrome patients: Long-term surgical stability

Maxillomandibular advancement surgery in obstructive sleep apnea syndrome patients: Long-term surgical stability

The 3-dimensional stability of maxillary osteotomies in cleft palate patients with residual alveolar clefts

Objectives—To evaluate the stability of maxillary osteotomies in cleft palate patients using miniplate fixation. Design—A prospective clinical study. Subjects—46 consecutive cleft palate patients with residual alveolar clefts and maxillary hypoplasia in one or more dimensions. These patients underwent standardised maxillary osteotomies and simultaneous bone grafting of the alveolar cleft over 44 months during 1988–1992. Titanium mini-plate fixation was used for the maxilla in all patients. Follow-up ranged from 6 to 51 months with a mean of 28 months. Main outcome measures—The 3-dimensional stability of maxillary osteotomies in cleft palate patients in the long term. Results—In the unilateral clefts, relapse in the horizontal plane was 22% and in the vertical plane 22.5%; in bilateral clefts, the relapse was 17.5% and 7% respectively, with no statistically significant difference between the two groups. Longitudinal analysis of the repositioned maxilla over a 3-year period showed that most of the relapse occured in the first 6 months and stabilised at 2 years postoperatively. Relapse in the transverse plane, based on analysis of the study models of 26 cases, ranged from 13.4% to 33.6%. A clockwise rotational relapse of the maxilla was noted in bilateral cases. Postoperative orthodontics compensated for the horizontal relapse by increasing incisor proclination to maintain positive overjet. There was no significant difference between the relapse of bimaxillary cases and that of maxillary osteotomies alone. Conclusion—The long-term 3-dimensional surgical stability, using miniplate fixation, has decreased the relapse of cleft maxillary osteotomies with simultaneous alveolar bone grafting to a level comparable to that of maxillary osteotomies in non-cleft patients.

Atlantoaxial arthrodesis using interlaminar clamps. An improved technique.

The atlantoaxial articulation is a multiaxial joint with a freedom of motion that presents unique problems in achieving surgical stability. Several methods of atlantoaxial arthrodesis have been established with varying degrees of immediate and sustained stability and safety. This study describes a new, improved method of posterior atlantoaxial arthrodesis, using (Halifax) interlaminar clamps with interposed bone graft, which provides distinct benefits over existing techniques. This method achieved atlantoaxial union within 12 weeks in 80% of the study's patients (20/25). The clamp fixation was revised in two patients, with subsequent fusion. Three other patients required revision surgery for nonunion due to loosening of the clamp. This was usually caused by incomplete tightening of the screws, with subsequent loosening or dislocation of the device. Possible clamp loosening is a potential problem with the currently available system, and may be a result of the clamp design. Techniques to minimize this risk and suggestions for improvement in the device are discussed. Nonunion is more likely to develop in patients with rheumatoid arthritis. If nonunion occurs, the pseudarthrosis is generally between the posterior bone graft and the ring of C1.

A Method for Reconstruction of Large Full-Thickness Defects of the Bony Thorax

Wide resection in 12 cases of malignant or potentially malignant lesions of the chest wall resulted in full-thickness loss of skeleton and frequently of overlying soft tissues (defect greater than or equal to 15 cm in its smallest diameter or at least 90% of the sternum resected). In reconstruction of the defect, steel bars were used to replace lost ribs and a double layer of Marlex mesh for intercostal spaces. Soft-tissue coverage and primary closure were accomplished with current plastic surgical procedures and good stability of the chest wall was achieved. Protracted respiratory support was required in only one case. Postoperative pain was managed with epidural anesthesia and routine analgesics. Functionally and cosmetically satisfactory long-term results were obtained, with no infection and no need for removal of prosthetic material. The overall 5-year and 10-year actuarial survival rates were 60% and 37.5%. If lesions are radically resectable, the extent of thoracic wall resection need not be restricted because of inability to close the defects.

Le fort I maxillary osteotomies in cleft palate cases: Surgical changes and stability

Surgical and postsurgical changes in maxillary position following transpalatal osteotomy at the le Fort I level in 30 patients with clefts of lip and palate were evaluated cephalometrically. By superimposing on natural reference structures, a more accurate and detailed evaluation of change in maxillary position was possible than by using conventional cephalometric analyses. The mean horizontal advancement was 9 mm, with a mean vertical change of 3 mm. While it is customary to express postsurgical relapse as a percentage of surgical change (in this case 7% mean horizontal relapse and 23% mean vertical relapse), the most remarkable finding to emerge from this study was the variability in surgical and postsurgical change which would be obscured by concentrating on descriptive statistics. Postsurgical change was related to the amount of surgical change, but the correlation coefficients are quite low, and so other factors must be responsible for a significant proportion of any relapse.

Pediatric spinal injury: the very young.

Maturity of the spine and spine-supporting structures is an important variable distinguishing spinal cord injuries in children from those in adults. Clinical data are presented from 71 children aged 12 years or younger who constituted 2.7% of 2598 spinal cord-injured patients admitted to the authors' institutions from June, 1972, to June, 1986. The 47 children with traumatic spinal cord injury averaged 6.9 years of age and included 20 girls (43%). The etiology of the pediatric injuries differed from that of adult injuries in that falls were the most common causative factor (38%) followed by automobile-related injuries (20%). Ten children (21.3%) had spinal cord injury without radiographic abnormality (SCIWORA), whereas 27 (57%) had evidence of neurological injury. Complete neurological injury was seen in 19% of all traumatic pediatric spinal cord injuries and in 40% of those with SCIWORA. The most frequent level of spinal injury was C-2 (27%, 15 cases) followed by T-10 (13%, seven cases). Upon statistical examination of the data, a subpopulation of children aged 3 years or younger emerged. These very young children had a significant difference in level of injury, requirement for surgical stability, and sex distribution compared to 4- to 12-year-old children.

Vertical maxillary deficiency with cleidocranial dysplasia: Diagnostic findings and surgical-orthodontic correction

An anatomic pattern of dentofacial deformity consistent with the diagnosis of vertical maxillary deficiency (short face syndrome, Type 2) was observed in a patient with cleidocranial dysplasia. Detailed description of diagnostic findings and the coordinated sequence of surgical-orthodontic care over a 16-month period of follow-up are presented. An 11 mm lengthening of facial height was obtained. Results of surgical and orthodontic stability are presented. A relationship between conditions with anodontia or pseudo-anodontia and vertical maxillary deficiency is hypothesized.

Response during anesthesia and surgery; effect of psychological factors.

Summary This research received its impetus from the occurrence of several cardiac arrests during surgery, with attendant newspaper publicity, plus the more frequent situation in surgical suites of highly unstable cardiac and cardiovascular response without demonstrable organic causation. The empirical evidence of the importance of the effects of psychological factors in surgical response led to the hypothesis that there is a relationship between psychological or personality factors and stability of response during surgery. Four classes of variables were identified: (1) "predictor" variables or psychological and/or physiological measurements of preoperative patients, (2) predictions made by clinical psychologists using the psychological measures in an effort to forecast the surgical stability, and the "criterion" variables of (3) physiological measurements made during surgery, and (4) clinical evaluations made by anesthesiologists using these measures. Thus it was possible to search for relationships between any of the factors considered pertinent. After a sample of psychological variables and tests to measure them were selected, 25 patients were examined preoperatively. Clinical psychologists attempted to predict the patients' stability of response in the operating room by using only the psychological test protocols. Patients were given extra clinical tests to assure normal physical status, and their surgical and anesthesiological management was standardized. Comparable types of surgery were performed on the patients. Physiological measures taken during surgery were evaluated by anesthesiologists who determined the stability of surgical response. Spearman rank-difference correlations (rho) were computed between the ranked measures of the four classes of variables, and the following conclusions were suggested: The study demonstrated the possibility of finding a relationship between psychological factors and patient response to surgery under anesthesia. Rorschach reaction time, deformed responses on the Rorschach, and cold pressor test results appeared to show promise for continued investigation of specific factors which may help to predict unstable response during surgery. Clinical psychologists utilizing a variety of psychological test protocols were able to predict somewhat in excess of chance not only the physiological surgical stability but also the evaluations of anesthesiologists of patients' clinical stability. There was objective confirmation of the importance of changes in systolic blood pressure as a major index used by anesthesiologists. Further research effort is being applied to extend the investigation by the author, and it appears that interest may have been generated elsewhere to assist surgeons and anesthesiologists in one of their major problems.