Osteotomy site healing following mandibular sagittal split osteotomy and rigid fixation with polylactide biodegradable screws.

Follow-up of 47 patients, treated using mandibular bilateral sagittal split osteotomy and self-reinforced poly-L-lactide acid (SR-PLLA) screws for rigid internal fixation, is presented. The focus was on clinical and radiological osteotomy healing. The average follow-up time was 2.1 years (range 0.5-5 years). Clinical recovery and radiological osteotomy healing during follow-up were uneventful. Osteolytic changes were seen around the SR-PLLA screws in 27% of cases. The majority of the screw canals remained as radiolucent shadows without bony filling.     

Biomechanical testing of resorbable screws used for mandibular sagittal split osteotomies

PURPOSE: The object of the study was to determine the suitability of specific resorbable screws for fixation of mandibular sagittal split osteotomies by in vitro biomechanical strength testing. MATERIALS AND METHODS: Resorbable screws (2.5 mm diameter) composed of a polylactic acidpolyglycolic acid copolymer were placed in an inverted L-pattern in overlapping urethane blocks representative of sagittal split mandibular surgery. In an in vitro model at room temperature, the test specimens were statically loaded until tensile failure occurred. On a different set of test specimens, dynamic testing was done in an in vitro water bath at body temperature through cyclic loads representative of mastication until failure. RESULTS: In static testing, three 2.5-mm resorbable screws sustained an average peak load of 131 Kiloponds (Kp) (standard deviation, 5.2 Kp) with 5.5% strain at yield. In dynamic testing, the resorbable screws tolerated a 45.3-Kp load for an average of 340,675 cycles (22,783 standard deviation). Several of these test specimens did not ultimately fail and were further evaluated by static testing with an average load of 77.4 Kp until fixation failure occurred. CONCLUSIONS: These laboratory results indicate a relatively high resistance to biomechanical loads representative of mastication and suggest that 2.5-mm resorbable screws of this particular polylactic acid-polyglycolic acid copolymer may be effective in fixation of the postoperative unrestrained sagittal split mandibular osteotomy.     

Lag screws in sagittal split osteotomies: should they be removed?

The use of stainless steel lag screws to provide rigid internal fixation for sagittal split osteotomies was first described more than 17 years ago. It was shown that the need for intermaxillary fixation could be eliminated and that lower relapse rates could be produced. However a decade later, removal of the screws was still being advocated. In this study, 48 patients had a total of 259 screws inserted over a 5 year period. Twenty six screws were removed 10 months following insertion. Most of these were removed in the absence of any symptoms although a few were palpable or tender to touch. None of the screws removed were loose nor was there any evidence of infection or corrosion associated with them. The long term consequences of screw retention are discussed and it is suggested that they do not need to be removed routinely.     

The incidence of postoperative wound healing problems following sagittal ramus osteotomies stabilized with miniplates and monocortical screws.

PURPOSE: Titanium plates and monocortical screws are commonly used to stabilize the mandible following sagittal split ramus osteotomies. Despite widespread use of this type of fixation, there is a paucity of large studies evaluating the infection rate and need for hardware removal. MATERIALS AND METHODS: This study is a retrospective cohort evaluation of 1,066 consecutive mandibular sagittal ramus osteotomies in 533 patients, performed between January 2002 and December 2003. All osteotomies were stabilized with 4-hole miniplates and 2.0 mm x 5.0 mm monocortical screws. Study variables included disturbances of wound healing, age, gender, plate and screw position, direction of mandibular movement, adjunctive procedures performed, and the patient's medical history. Data were collected by chart and radiographic review. The above variables were analyzed using Fisher's exact test, Chi-square, Cochran-Armitage Trend Test, and multiple logistic regression. RESULTS: Of 533 patients 26% (138) demonstrated wound healing problems. This occurred in 15% of all 1,066 osteotomy sites. 6.5% of plates required removal in 10% of patients. In no case did disturbance of wound healing or plate removal result in non-union or relapse of the osteotomy. Wound healing problems were fewer when mandibular osteotomies were done in conjunction with maxillary surgery (18.9% versus 29.1%). Disturbances of wound healing were not related to the direction of movement of the mandible and were lower when hardware was placed closer to the inferior border. CONCLUSION: An overall low incidence (6.5%) of hardware infection requiring plate removal was found in this study. Screw proximity to the osteotomy site did not correlate with higher rates of healing problems, but there was a statistically significant trend of fewer disturbances of healing when the hardware was placed closer to the inferior border of the mandible.     

Mandibular,sagittal split osteotomies fixed with biodegradable or titanium screws: a prospective,comparative study of postoperative stability

OBJECTIVE: Comparison of skeletal stability following bilateral sagittal split osteotomy (BSSO) advancement of the mandible fixed with titanium or biodegradable bicortical screws. STUDY DESIGN: Forty consecutive patients underwent mandibular advancement by means of BSSO performed with a standardized technique. In 20 patients rigid fixation was achieved by means of titanium bicortical screws; the other 20 patients were fixed with biodegradable copolymer screws made of poly-L-lactic acid (82%) and polyglycolic acid (18%). Lateral cephalograms were obtained 1 week preoperatively, 1 week postoperatively and after a minimum of 6 months postoperatively. Relevant skeletal points were traced and digitized to evaluate 2-dimensional skeletal change. Changes at each time point were analyzed and compared statistically. RESULTS: There was no statistically significant difference in long-term stability between the 2 groups. No clinical or radiographic evidence of wound healing problems were noted. CONCLUSION: Resorbable poly-L-lactic/polyglycolic acid copolymer bicortical screw fixation of a BSSO is a viable alternative to titanium screws for the fixation of advancement BSSO.     

Bicortical biodegradable screws for rigid fixation of traumatic sagittal split mandibular fracture

Rigid fixation is the most important issue in the bone healing process. Although internal metallic bone fixation has become increasingly popular over the past 10 years, the presence of several potential problems of metallic bone implants with the popularity of the use of biodegradable plates and screws for craniomaxillofacial fixation have increased in the last 10 years. Rigid fixation of bony fragments was achieved by bicortical applied biodegradable screws in a patient with a sagittal oblique mandibular fracture. Precise bone reduction was maintained with bicortical applied biodegradable screws in the postoperative period. The postoperative period was uneventful and the patient retained the intraoperatively achieved perfect occlusion within a 9-month follow-up period. In this particular case, the advantages of use of resorbable fixation systems are combined with the advantages of bicortical screw fixation of split osteotomy without sacrificing the stability of rigid fixation.     

Perioperative complications following sagittal split osteotomy of the mandible.

INTRODUCTION: The aim of this study was to review complications in a series of 1264 consecutive patients who were operated in a single centre during a 20-year-period. MATERIAL AND METHODS: Complications were documented, their incidences calculated and compared with data from the literature. RESULTS: In 35 patients (2.8%) infection developed requiring extraoral incision and drainage; in 27 patients (2.1%) the inferior alveolar nerve was inadvertently cut; 18 patients (1.4%) had to undergo re-operation due to bending or fracture of osteosynthesis material; 15 patients (1.2%) suffered from bleeding complications; in 12 patients (0.9%) an unfavourable split occurred. In 8 patients (0.6%) foreign bodies were left in situ; in 7 patients a partial weakness of the facial nerve occurred, which was permanent in 1 patient. Six patients (0.5%) with a significantly higher age than average (mean: 33.6 years in comparison with 23.1 years) developed non-union at the site of osteotomy, and the mandible had to be bone grafted. Two patients (0.2%) developed osteomyelitis, and in one patient airway problems led to a need for tracheostomy (0.1%). CONCLUSION: Although some of these complications of bilateral sagittal split with osteotomy carry severe limitations in health related quality of life, it remains an overall safe procedure, demanding, however, comprehensive informed consent. Good knowledge of technical reasons for these complications should help to reduce their incidence.     

Long-term neurosensory deficits following transoral vertical ramus and sagittal split osteotomies for mandibular prognathism

Twenty-six patients who had been treated for mandibular prognathism by either bilateral sagittal split osteotomy or transoral vertical ramus osteotomy were evaluated by neurosensory examination. Neuropathy was demonstrable in 28.8% of the 52 mental nerves examined. The incidence of neuropathy was significantly higher in the bilateral sagittal split osteotomy group than in the transoral vertical osteotomy group.     

Finite element analysis of a tandem screw configuration in sagittal split osteotomy using biodegradable osteosynthesis screws

The goal of the present study was to determine the mechanical stability of selected osteosynthesis screws in a paired linear configuration in cases of bilateral sagittal split osteotomy of the mandible. A mandible model was created that consisted of 22,846 elements and 4,879 nodes. The following screws were tested in the tandem screw configuration: the poly-L-lactic acid (PLLA) in accordance with Harada and Enomoto, the Isosorb screw (Aesculap, Germany), the BioSorbFX screw (Bionix Implants, Finland), and the Lactosorb screw (WL. Lorenz, USA). The mechanical parameters of the materials studied were adopted from the literature or were based on manufacturer information. With the precondition that the materials each be stressed to the ultimate tensile strength, the following chewing forces could be neutralized: 100 N by 2.0-mm titanium mini-screws, 117.5 N by PLLA screws in accordance with Harada and Enomoto, 90.0 N by Isosorb screws, 89.0 N by BioSorbFX screws, and 35.0 N by Lactosorb screws. Here the peri-implant bone was stressed within limiting values with the titanium miniscrew, and the PLLA screw according to Harada and Enomoto, but not the osteosynthesis material itself. The finite element method (FEM) appears suitable for simulating complex mechanical stress situations in the maxillofacial area. As a result, significant time and materials (animal tests) can be saved when developing new or modified materials     

Bilateral sagittal split osteotomies in an ambulatory care setting

Orthognathic surgery has made many advances since its inception. This,combined with modern day health economics, has necessitated changes in orthognathic surgical practice. The bilateral sagittal split osteotomy is evaluated as an ambulatory surgical procedure. Studies have proven the sagittal split osteotomy can be performed as an ambulatory procedure. Patient costs, as well as other issues that impact on the patient and health care provider, are reviewed. The need for additional outcome data to determine whether patient care or perception of care is affected is discussed.     

Intra-operative complications in sagittal and vertical ramus osteotomies

In orthognatic surgery of the mandibular ramus, intra-operative complications as a lesion of the inferior alveolar nerve, fractures of the osteotomised segments, incomplete sectioning, malpositioning of segments and haemorrhage may occur. In this report, intra-operative complications in 124 sagittal split osteotomies and 34 vertical ramus osteotomies, carried out in 80 patients, are described. The incidence of intra-operative complications in the sagittal split osteotomies was 25.8%. The complication occurring most frequently was incomplete sectioning (11.2%). This may be avoided by using the modified sagittal split technique. The incidence of complications in the vertical ramus osteotomies was 11.8%.     

Resorbable PLLA-PGA screw fixation of mandibular sagittal split osteotomies.

The purpose of this study was to evaluate the intraoperative placement and clinical effectiveness of resorbable copolymeric screws for mandibular sagittal split ramus osteotomies. Thirty-seven patients who underwent bilateral sagittal split osteotomies of the mandible were fixated with three 2.5-mm copolymeric poly-L-lactic-polyglycolic (PLLA-PGA) screws on each side. No postoperative maxillomandibular fixation was applied. Twenty-five patients experienced mandibular advancement and 12 patients had setbacks. The average advancement was 6.5 mm (range, 3-17 mm) and the average set-back was 5.2 mm (range, 3-8 mm). Intraoperative placement was uncomplicated and no screws were stripped during placement. No problems in immediate postoperative stability were encountered and relapse was not evident in any patient. Follow-up ranged from 3 to 17 months. The screw holes remained evident radiographically after 1 year. Two and one-half-millimeter copolymeric PLLA-PGA resorbable screws for mandibular ramus osteotomies appear to offer clinical results comparable with metallic screw fixation.     

A comparative study of temporomandibular symptoms following mandibular advancement by bilateral sagittal split osteotomies: rigid versus nonrigid fixation

Rigid fixation to attach proximal and distal segments during bony healing of osteotomy sites has become increasingly popular. The effects of rigid fixation on the temporomandibular joints have been questioned. The purpose of this study was to evaluate the effects of rigid fixation after bilateral sagittal split osteotomies on temporomandibular dysfunction symptoms. Forty patients who had mandibular advancement surgery were evaluated for temporomandibular joint dysfunction. Twenty had received rigid fixation, and twenty had received nonrigid fixation. It was determined that there was no statistically significant difference in temporomandibular signs or symptoms between patients who were treated with rigid internal fixation for bilateral sagittal split osteotomies for mandibular advancement and those patients who were treated with nonrigid wire fixation.     

Postoperative fractures of the lingual plate after bilateral sagittal split osteotomies

We encountered the unusual complication of postoperative fracture of the lingual plate in four patients after bilateral sagittal split osteotomy. We then did a retrospective review to identify possible risk factors. Over a 1-year period we did 52 bilateral split osteotomies. The patients' casenotes were examined and a number of variables were recorded, including surgical technique, and the patient's sex, age, presence or absence of third molars, and the height of the mandible in the region of the osteotomy. Significant risk factors were a vertical mandibular height of 2 cm or less distal to the last molar tooth (p=0.02), and a depth of 0.6 cm or less from the apex of last molar root or impacted third molar to the lower border (p=0.005).