Lag-screw osteosynthesis of mandibular condyle fractures: a clinical and radiological study

A Novel Screw Drive for Allogenic Headless Position Screws for Use in Osteosynthesis-A Finite-Element Analysis

Due to their osteoconductive properties, allogenic bone screws made of human cortical bone have advantages regarding rehabilitation compared to other materials such as stainless steel or titanium. Since conventional screw drives like hexagonal or hexalobular drives are difficult to manufacture in headless allogenic screws, an easy-to-manufacture screw drive is needed. In this paper, we present a simple drive for headless allogenic bone screws that allows the screw to be fully inserted. Since the screw drive is completely internal, no threads are removed. In order to prove the mechanical strength, we performed simulations of the new drive using the Finite-Element method (FEM), validated the simulations with a prototype screw, tested the novel screw drive experimentally and compared the simulations with conventional drives. The validation with the prototype showed that our simulations provided valid results. Furthermore, the simulations of the new screw drive showed good performance in terms of mechanical strength in allogenic screws compared to conventional screw drives. The presented screw drive is simple and easy to manufacture and is therefore suitable for headless allogenic bone screws where conventional drives are difficult to manufacture.

Evaluation of 3D Trapezoidal Plates in Open Reduction and Internal Fixation of Subcondylar Fractures of Mandible: A Clinical Trial

Background  Fractures of the mandibular condyle are common and account for 25% to 50% of all fractures of the mandible. Various methods exist for open reduction and internal fixation (ORIF) of condylar fractures. This study was done to explore three-dimensional (3D) plates as a viable option. Aim  This study aims to evaluate the effectiveness of 3D trapezoidal plates in open reduction and internal fixation of subcondylar fractures. Materials and methodology This was a non-randomized clinical trial conducted on 20 patients who reported at the Department of Oral and Maxillofacial Surgery, Tamil Nadu Government Dental College and Hospital, Chennai, India. The ORIF was done under general anesthesia. A retromandibular transmasseteric approach was used to expose the fracture site, and the fracture was stabilized using 3D titanium trapezoidal plates. Parameters, such as mouth opening, mandibular deviation, occlusion, surgical accessibility, fracture reduction, adaptability, the difference in ramal height, angulation of the fractured condyle, operative time, facial nerve weakness, implant failure, complications, and scar formation were assessed. Statistical analysis was done using Statistical Package for Social Sciences (SPSS), version 21 (IBM SPSS Statistics for Windows, Armonk, NY). Results  There was an improvement in mouth opening and occlusion in the immediate postoperative period. The surgical accessibility ranged from good to excellent. The fracture reduction was excellent in 60% of patients and good in 40%. In one patient, there was a transient weakness of the marginal mandibular nerve which recovered by three months. Another patient had a wound infection that subsided within the first postoperative week. None of the patients had a device failure during the six-month follow-up period. Conclusion  The trapezoidal 3D plates could be considered as a viable option for treating subcondylar fractures of the mandible in terms of surgical accessibility, stability, ease of device placement, stability of reduced fracture, reduced osteosynthesis material requirement, and minimal damage to the surrounding tissues.

Cortical lag screw fixation for the management of mandibular injuries

Objectives

Here, we present cases of mandibular fracture that were managed with the cortical lag screw fixation technique (CLSFT) in order to critically evaluate technique indications and limitations of application at various fracture sites.

Materials and Methods

This was a retrospective cohort study. The study sample was composed of patients suffering from mandibular fractures that were treated by the CLSFT. The outcome variables were fracture type, duration of surgery, number of screws, and pattern of application. Other study categories included patient demographics and causes of injury. Chi-square tests were used to assess descriptive and inferential statistical differences, and the P-value was set at 0.05.

Results

Thirty-three patients were included in the study sample, with a mean age of 30.9±11.5 years and a male predominance of 81.8%. The technique was applied more frequently in the anterior mandibular region (51.5%) than in other sites. Double CLSFT screws were required at the symphysis and parasymphysis, while single screws were used for body and angle regions. No intraoperative and postoperative variables were significantly different except for surgical duration, which was significantly different between the sites studied (P=0.035).

Conclusion

We found that CLSFT is a rapid, cost-effective technique for the fixation of mandibular fractures yielding good treatment results and very limited complications. However, this technique is sensitive and requires surgical expertise to be applied to mandibular fractures that have specialized characteristics.

Retromandibular vein position and course patterns in relation to mandible: anatomical morphologies requiring particular vigilance during sagittal split ramus osteotomy

Major bleeding associated with sagittal split ramus osteotomy (SSRO) involves vessels such as the inferior alveolar, facial, and maxillary arteries and veins, and the retromandibular vein (RMV). The present study aimed to clarify and classify the three-dimensional variations in RMV position and course direction in relation to the mandible. Specimens comprised a total of 15 scientific cadavers, and the relationship between RMV and the mandible lateral and posterior views was observed. We identified 3 patterns on the lateral view, the mean distance between the RMV and the posterior border of the ramus was 3.9 mm at the height of the lingula. A total of five course patterns were identified on the posterior view. In no course pattern, the RMV inferior to the lingula was lateral to its position superior to the lingual. The present findings suggest that it may be possible to predict correlations with intraoperative bleeding risk. Further study is planned using contrast computed tomography in patients with jaw deformity for skeletal classification.

The high sub-mandibular approach: Our experience about 496 procedures

INTRODUCTION

The potential drawbacks of surgical approaches to neck and base fractures of the mandibular condyle (visible scare, facial nerve injury) are still considered by many surgeons as a brake for open reduction and internal fixation. The aim of our study was to analyze the results in terms of access, scare quality and complications that could be noticed in a 12 years period of time with the use of the high sub-mandibular approach (HSMA) we first described in 2006 for the surgical treatment of neck and base fractures.

MATERIAL AND METHOD

All the files of patients operated on for condylar neck and base fractures approached by mean of a HSMA between January 2006 and December 2018 in our department and containing information concerning age, sex, type of fracture, kind of osteosynthesis material, operating time, name of the surgeon, postoperative complication linked to the approach, scare quality at 6 months follow-up at least were included. The skin incision and the dissection planes followed the original publication of Meyer et al. in 2006.

RESULTS

434 patients (sex ratio: 2.06, mean age: 32, 496 approaches) met the inclusion criteria. Following the AO classification, 21.2% of the fractures were classified as neck fractures and 78.8% as base fractures. 97.6% of all fractures were stabilized by mean of a 3D plate (TCP® plate, Medartis, Basel-CH), the remaining ones by mean of a combination of 1.2, 1.5 and 2.0 straight plates. Mean operating time was 40minutes per side. Patients were operated on by senior surgeons in 71.7% of the cases and by trainees under supervision for the others. Concerning the complications linked to the approach, we noticed 11 (2.2%) temporary (0 definitive) paresis of the facial nerve, 1 (0.2%) hematoma and 1 (0.2%) abscess that both needed revision. Scare was hypertrophic or considered as unaesthetic by the patient in 5 cases (1%).

DISCUSSION

The HSMA, if performed as initially described, is a safe and quick procedure compared to other cutaneous approaches. It gives access to all base fractures and to most of neck fractures. The very low rate of facial nerve complications is mainly explained by the plane by plane dissection making it very easy to avoid the facial nerve branches or to check them when encountered. The HSMA is particularly suited to the use of TCP plates as the upper holes of these plates, placed horizontally, are easy to reach from below. The HSMA is therefore still our preferred cutaneous approach to the condylar process.

Mandibular Subcondylar Fractures: A Review on Treatment Strategies

Condylar injuries are often subjected to discussion and controversy in maxillofacial surgery as they constitute many of the facial fractures. The condylar area has a great clinical value due to its important components. Vital components in this area are susceptible to functional disability due to either the fracture itself or the subsequent surgical intervention. Each of the strategies for the management of these fractures has its advantages and disadvantages. As there are controversies around management of condylar fractures, different treatment modalities are suggested in literature, so this paper reviews different treatment strategies of the following types of fractures in adults: 1-Closed reduction with maxillomandibular fixation, 2-Open reduction with internal fixation, 3-Endoscopic-assisted reduction with internal fixation. In conclusion, we declare that the endoscopic surgery is certainly a good replacement for approaches through the skin, for subcondylar fractures, but still more randomized clinical trials are needed to be carried out on this issue.

Evaluation of Retro Mandibular Approach to Open Reduction and Internal Fixation of Condylar Fractures: A Cross-sectional Study

PURPOSE

The present study was carried out to evaluate the usefulness of mini retromandibular approach on accessibility, scarring and stability in open reduction and internal fixation of sub condylar fractures.

MATERIALS AND METHODS

Fifteen patients underwent open reduction and rigid fixation of middle and low subcondylar fractures, with mini-retro mandibular approach.

RESULTS

No signs of infection were observed in any patient postoperatively. Surgical scar was imperceptible and esthetically acceptable in all the cases. Out of 15 patients, only one patient had discrepancy in occlusion and after 2 months satisfactory centric occlusion was achieved. Salivary fistula (parotid fistula) was observed in 3 cases within 1 week postoperatively, which was treated spontaneously with the use of hypertonic saline. Transient facial nerve weakness was observed in 2 patients, in one patient it resolved in 4 weeks postoperatively and in second patient 3 months postoperatively. Mouth opening increased in all the patients with time. Average mouth opening at 1 week interval was 19.6 mm, at 2 months interval 28.2 mm, and after 6 months 38.33 mm suggesting that mouth opening gradually increased with time. At the end of 2 months postoperatively none of the patients had any restriction in lateral movements. At 2 months postoperatively 4 patients had deviation but none of the patients had any deviation 6 months postoperatively.

CONCLUSION

It is evident from the results of our study that open reduction and internal fixation using mini-retromandibular approach is good treatment option in management of mandibular condylar fractures.

Treatment of low subcondylar fractures--a 5-year retrospective study

The aim of the present study was to retrospectively review the treatment outcome of low subcondylar temporomandibular joint fractures. The retrospective analysis was performed on all patients treated for low subcondylar fractures (below the sigmoid notch) between 2006 and 2011. Patients were divided into two groups: the closed reduction group (maxillomandibular fixation, MMF) and the open reduction group (anteroparotid transmasseteric (APTM) approach). Out of 129 condylar fractures, a total of 37 patients met the inclusion criterion of a fracture below the sigmoid notch (low subcondylar). Ten patients (seven males and three females) were treated using the APTM approach, and 27 patients were treated conservatively by MMF. In the open reduction group, two patients (20%) had limited mouth opening that resolved following physiotherapy; the closed reduction group had a similar percentage (18.5%) of mouth opening limitation (below 35 mm). No facial nerve damage was noted. Adult patients suffering from low subcondylar fractures can be treated by open reduction and internal fixation using the APTM approach, which was found to be a safe and reproducible procedure with no facial nerve damage; however this is a surgical procedure with a shallow learning curve.

Severe open bite due to traumatic condylar fractures treated nonsurgically with implanted miniscrew anchorage

This case report illustrates the use of miniscrews to treat a patient with an open bite caused by mandibular condylar fractures. The patient was 36 years old when she visited our hospital with a chief complaint of difficulty with chewing. She had suffered condylar and maxillary bone fractures in a traffic accident 6 months before her visit. She had an anterior open bite and Angle Class II molar relationships. Her mandibular midline was deviated to the right relative to the maxilla. The cephalometric analysis showed a skeletal Class II relationship. Titanium miniscrews were implanted in the bilateral maxillary buccal areas. The maxillary dentition was retracted and intruded by using elastomeric chains and miniscrews. After this treatment, an Angle Class I molar relationship was achieved, her overjet and overbite became ideal, and a good facial appearance was obtained. The total active orthodontic treatment period was 33 months. Treating an open bite with molar intrusion often leads to counterclockwise rotation of the mandible; however, in this patient, the mandible was moved anteriorly and upward. We believe that this movement was caused by the patient's condylar fractures and the subsequent remodeling. Although there was some relapse, our results suggest that implant anchorage is useful for correcting anterior open bites originating from condylar fractures.

Management of Subcondylar Fracture through Intraoral Approach with Rigid Internal Fixation

BACKGROUND

In Oral and Maxillofacial Surgery, the majority of the condylar fractures are treated by closed reduction with generally satisfactory long term results. But in such cases of closed reduction, patient will be uncomfortable owing to long term application of inter maxillary fixation (IMF). Where as, Disadvantages of extra oral open reduction and fixation of condylar fracture includes facial nerve damage, facial scars etc. which are surely eliminated by the intraoral reduction and rigid fixation.

AIMS AND OBJECTIVES

The present study was conducted to determine the efficacy of reduction and fixation of low sub-condylar fractures through intra-oral approach.

METHODOLOGY

In this study, ten patients with low sub-condylar fracture, reported to department of Oral and Maxillofacial Surgery. P.M.N.M. Dental College and Hospital Bagalkot were included. These patients were treated by open reduction and internal fixation through intra-oral approach. All the patients were evaluated postoperatively for mouth opening, occlusion and mandibular deviation with regular radiographic examination for 6 weeks.

RESULTS

All operated patients followed for 6 weeks, maximum mouth opening was more than 40 mm in seven patients (range from 40 to 50 mm) and less than 40 mm in three patients. Occlusion was satisfactory in all and none of the patients showed deviation of mandible on mouth opening. Statistical analysis showed that postoperative mouth opening was significant ('t' value = 7.88, 'P' = (0.000) < 0.05) and the test result was significant (S) at 5% level of significance. Statistical analysis of deviation of mouth opening was nonsignificant ['t' value = 1.96, 'P' value (0.081), 0.05]. For occlusion standard photographs were obtained at sixth week and found minor occlusal corrections in two patients are treated by elastic traction for few days.

DISCUSSION AND CONCLUSION

Open reduction with internal fixation through intraoral approach has proved to be safe for early function and also effective by avoiding the patient discomfort due to long term intermaxillary fixation, psychological effect, facial nerve damage, facial scar and weight loss.

Comparison of single vs double noncompression miniplates in the management of subcondylar fracture of the mandible

PURPOSE

The purpose of this study was to compare the functions of the condyle and complications after fixation of a subcondylar fracture of the mandible with two noncompression miniplates and a single non-compression miniplate.

MATERIALS AND METHODS

A total of 30 patients who required open reduction of a subcondylar fracture of mandible were selected for the study. The patients were randomly divided into two groups of 15 each. Group I comprised of patients treated with a single miniplate and Group II were treated with two noncompression miniplates. The patients were assessed for malocclusion, lateral deviation on opening, infection, plate removal, facial nerve function, the time taken in the surgery, and cost of implants used, in both the groups. All the parameters were compared statistically using the chi square test.

RESULTS

Out of 30 patients, inadequate reduction was noticed in one patient in Group I. Screw loosening occurred in two cases; both the cases were stabilized with a single miniplate. Screw loosening was always associated with chronic infection. In these cases, hardware removal was performed. Plate bending was observed in one case that was stabilized with a single miniplate. Malocclusion and lateral deviation occurred in this case. When two miniplate were used, no plate bending or screw loosening was observed. Malocclusion was observed in Group II.

CONCLUSION

Two plates for subcondylar fractures represent the best solution to obtain stable osteosynthesis in comparison to a single miniplate.

Combined surgical approach retromandibular and intraoral to subcondylar mandibular fractures

BACKGROUND

Condylar and subcondylar fractures are very common and account for at least one third of all mandibular fractures. In literature, little agreement exists about the management of extracapsular condylar and subcondylar fractures in adults. Some studies provide better results of occlusion, masticatory function, mouth opening, and bone morphology with surgical treatment. Conversely, other studies report excellent results with conservative treatment avoiding complications such as facial nerve injury and unsightly scar.

METHODS

In this study, we report our experience of 25 condylar/subcondylar fractures. We report the case of a man with bilateral subcondylar fractures treated by a double surgical approach, intraoral and retromamdibular. Intraoral approach lets us dissect the masseter and disconnect the temporal muscle tendon, thus favoring further reduction of fracture stumps, whereas retromandibular approach favors a good operative field and the positioning of titanium microplate.

RESULTS

Postoperative monitoring reported good results of occlusion. Postoperative computed tomographic scans show the good reduction and positioning of titanium miniplate.

Transgingival lag-screw osteosynthesis of alveolar process fracture

Fracture of the alveolar process is a common injury. In some cases, traditional fixation may not be possible. The teeth needed for splinting or mandibulo-maxillary fixation may be missing. The fracture line and soft tissue injury may jeopardize the blood supply of the broken bone. In these extreme and rare situations, the best rehabilitation is needed to avoid the loss of hard and soft tissues, and a secondary reconstruction is required. Between January 2003 and December 2006, of 468 cranio-facial trauma patients studied, alveolar process fracture was reported in 28 (6%) cases. In six (1%) cases, the anatomy of the fracture lines, and the position and number of the remaining teeth made splinting and mandibulo-maxillary fixation impossible. Patients were treated with a transgingival lag-screw (TLS) osteosynthesis. All patients healed well with no complications. There was no bone or tooth loss in the surgical area, and broken fragments were not absorbed. The TLS technique is recommended for alveolar fractures when the blood supply is jeopardized and dental splinting or mandibulo-maxillary fixation is not possible. There is no need for flap reflection.

Transmasseter approach to condylar fractures by mini-retromandibular access

PURPOSE

The published data are full of evidence that surgical treatment of condylar fractures, performed through an intraoral or extraoral approach, leads to better results than nonoperative treatment. Intraoral surgery can be technically demanding, and an extraoral approach presents risks of facial nerve injuries and visible scarring. The mini-retromandibular approach we have described allows the treatment of condylar fractures at any level in a simplified and rapid manner while reducing the risk of complications common to the other techniques.

PATIENTS AND METHODS

A total of 33 patients with 38 condylar fractures were treated with a 20-mm mini-retromandibular approach. The mean operative time was 33 minutes (range 17 to 56). One patient in the present study was only 14 years old at surgery, which was performed 25 days after the associated trauma.

RESULTS

Correct anatomic reduction and occlusion were achieved in all cases. Additionally, all patients showed normal articular function. Infection of the surgical site occurred in the first 2 surgical cases. In another patient, an additional operation was necessary to fix an erroneously reduced fracture, which had occurred because of insufficient surgical access (15 mm). No facial nerve injury was observed, and all surgical scars were barely visible.

CONCLUSIONS

We suggest that the mini-retromandibular approach outlined in the present study should be the technique of choice for condylar fracture management, because it allows for easy, fast reduction and synthesis while minimizing the risk of facial nerve injury and visible scars.

Clinical experience with osteosynthesis of subcondylar fractures of the mandible using TCP plates

AIM

To evaluate the clinical and radiological results obtained with a new kind of osteosynthesis device (Modus TCP) plates, Medartis, Basel, Switzerland), especially designed for low subcondylar fracture (LSCF) and high subcondylar fracture (HSCF) of the mandible in association with the high submandibular approach (HSMA).

METHOD

A prospective clinical and radiological study was carried out over a 41-month period. All adult patients suffering from a displaced LSCF or HSCF who consented to the surgical treatment were included in the study. All fractures were operated on using an HSMA and were stabilised using a 4- or 9-hole TCP((R)) plate. No intermaxillary fixation was used and a soft diet was started on the 1st postoperative day. Clinical examinations and control X-rays were carried out on the 10th postoperative day, in the 1st, the 3rd and, at least, in the 6th postoperative months.

MATERIAL

Sixty-four patients (12 females, 52 males - mean age: 28.3) with a total of 75 fractures (54 LSCF, 21 HSCF) were included in the study. Mean postoperative follow-up was 14 months.

RESULTS

In the 6th postoperative month, all fractures were consolidated in 79% of the cases in an anatomical position. A secondary displacement of the fracture occurred in 6.6% of the cases. Plate fracture was not observed. Dental occlusion remained unchanged in 94% of the patients. The mandibular movements (mouth opening, protrusion, lateral movements on the unfractured and fractured side) had normal mean values (49.5, 10.4, 12.8, 12.1mm, respectively). These movements were symmetrical in 95% of the patients. No patient complained about articular pain or noise. No facial nerve palsy was noticed, not even a transiently one. All patients but one found the scars acceptable.

CONCLUSION

TCP plates, in association with HSMA, were found to be an efficient osteosynthesis device for stabilising subcondylar fractures.

Development and biomechanical testing of a new osteosynthesis plate (TCP®) designed to stabilize mandibular condyle fractures

INTRODUCTION

In this paper, the different steps of development and experimental validation of a new type of three-dimensional (3-D) trapezoidal osteosynthesis plate (Modus TCP 2.0, Medartis, Basel, Switzerland) is described. These plates have been designed to stabilize sub-condylar and condylar neck fractures of the mandible.

MATERIAL AND METHODS

In order to apply the principles of functionally stable osteosynthesis to the mandibular condyle, i.e. to put the plate as close as possible to the tensile strain lines occurring during function, two new 4- and 9-hole 3-D trapezoidal plates were designed. Tests were conducted on fresh human mandibles before and after osteosynthesis of a standardised unilateral sub-condylar 'fracture', and a static biting exercise between the ipsilateral first molars was reproduced on a test bench. The resulting condylar fragment displacement in the sagittal plane was measured and the alterations of the condylar tensile strain lines induced by the osteosynthesis were investigated by using photoelastic strain tests.

RESULTS

None of the plates broke. No macroscopic condylar displacement was noted when assessing the quality of the primary stabilization. Strain analysis showed the ability of these 3-D plates to transmit physiological strains across the fracture line and the absence of potentially damaging strains around the plate.

DISCUSSION

These results were accredited to the 3-D and trapezoidal features of the plates.

CONCLUSION

The Modus TCP plates experimentally fulfil the principles of functionally stable osteosynthesis in the condylar region and are able to resist physiological strains.

Biomechanical comparison of plating techniques for fractures of the mandibular condyle

We compared the biomechanical behaviour of various rigid internal fixation techniques for treatment of fractures of the mandibular condylar process. Fifteen sheep hemimandibles were used to evaluate three bicortical plating techniques. A custom-made 3-point biomechanical test model was used for the samples. Each group was tested with compression forces by an Instron Lloyd LRX machine. The resistance to forces (N) that caused displacements of 1.75 and 3.50mm were compared using the Instron software programme and displacement graphics. There were no significant differences among the three groups for displacements of 1.75 and 3.50mm. Our study showed that the titanium miniadaptation plates, minicompression plates, and the absorbable miniplates did not differ significantly in their biomechanical behaviour.

Fractures of the mandibular condyle: A review of 466 cases. Literature review, reflections on treatment and proposals

INTRODUCTION

The incidence of condylar fractures is high. Condylar fractures can be extracapsular (condylar neck or subcondylar) or intracapsular, undisplaced, deviated, displaced or dislocated. Treatment depends on the age of the patient, the co-existence of other mandibular or maxillary fractures, whether the condylar fracture is unilateral or bilateral, the level and displacement of the fracture, the state of dentition and the dental occlusion, and the surgeon's experience.

PURPOSE

This report presents the experience acquired in the treatment of 466 condylar fractures over 7 years, reviews the pertinent literature and proposes guidelines for treatment.

MATERIAL AND METHODS

The archives of KAT, General District Hospital between 1995 and 2002 were scrutinized and the condylar fractures were recorded. The aetiology, age, sex, level of fracture, degree of displacement, associated facial fractures, malocclusion, and type of treatment were noted.

RESULTS

Four hundred and sixty-six condylar fractures were admitted, the male:female ratio was 3.5:1. Road traffic accidents were the main cause and most fractures were unilateral, displaced, subcondylar, occurred on the left side and were treated conservatively.

CONCLUSIONS

Early mobilization is the key in treating condylar fractures. Whilst rigid internal fixation provides stabilization and allows early mobilization, conservative treatment is the treatment of choice for the majority of fractures. Children and intracapsular fractures are treated conservatively with or without maxillo-mandibular fixation. Open reduction is recommended in selected cases to restore the occlusion, in severely displaced and dislocated fractures, in cases of loss of ramus height, and in edentulous patients. It may be considered in those with 'medical problems' where intermaxillary fixation is not recommended.

Experimental evaluation of three osteosynthesis devices used for stabilizing condylar fractures of the mandible

INTRODUCTION

The purpose of the study is to evaluate experimentally the quality of the primary stability achieved in treating low subcondylar fractures by means of three different osteosynthesis devices.

MATERIAL AND METHODS

The devices, a standard four-hole plate, an axial lag screw and a three-dimensional rectangular plate were tested on fresh isolated human mandibles. Testing was done on a test bench by reproducing static biting exercises between the first molars on the side of the fracture. The quality of the osteosynthesis was assessed by measuring the macroscopic amount of fragment displacement and on the device's ability to diffuse the mechanical strain within the fractured area by photoelastic stress analysis.

RESULTS

The straight plates provided the worst restoration. This was explained by the unfavourable position of the plate along compression lines. The axial lag screws allowed average stability. This was due to the difficulty of intra-medullary positioning of the screw, and by the compression of the fracture line. Rectangular plates allowed good stability associated with rather good restitution of the strains. These good results were assigned to the shape of the plate, one of its arms approximating the tensile strain lines.

CONCLUSION

Positioning and shape of the osteosynthesis device are of prime importance for condylar fracture stabilization. None of the three tested devices was optimal but the three-dimensional plate was the best. There is a need to develop the geometry of new plates.

Treatment of mandibular condylar process fractures: Biological considerations

The topic of condylar injury in adults has generated more discussion and controversy than any other in the field of maxillofacial trauma. It is an important subject because such injuries are common and complications of trauma to the temporomandibular joint (TMJ) are far-reaching in their effects. Why are there so many different methods to treat this injury? How can seemingly disparate treatment options all produce satisfactory outcomes in the majority of patients? The reason lies with the biological adaptations that occur within the masticatory system that are poorly understood, not readily quantifiable, and variable from one person to the next. This discussion presents our current understanding of the adaptations that must occur to provide the patient with a satisfactory outcome. The adaptations for patients treated open are different than for those treated closed. However, it is when these adaptations fail to occur that unsatisfactory outcomes occur, regardless of how they were treated.

Resorbable poly-l-lactide plates and screws for the treatment of mandibular condylar process fractures: a clinical and radiologic follow-up study

PURPOSE

The purpose of this study was to determine whether a resorbable poly-l-lactide (PLLA) miniplate system could be used to treat mandibular condylar process fracture.

PATIENTS AND METHODS

Fourteen patients (12 males, 2 females, aged 23.1 +/- 5.7 years) who had mandibular condylar process fractures treated with PLLA implants were recalled for follow-up clinical and radiologic examinations at 3 years.

RESULTS

Mouth opening recovered to more than 35 mm and occlusion was stable in all patients. There was no facial asymmetry 3 months postoperatively. Two patients had mild chronic postoperative tenderness at the implantation site; however, there was no wound infection. All fractured mandibular condyles showed anatomic good reduction and long-term stability with the use of resorbable miniplates and screws. Bone healing was satisfactory in all patients, and there was no evidence of abnormal resorption of the condylar process. The screw holes remained evident after 3 years. Screw holes in 2 patients showed enlargement on radiographic examination.

CONCLUSION

The PLLA miniplate system provides reliable stability when used for the fixation of mandibular condylar process fractures.

Photoelastic analysis of bone deformation in the region of the mandibular condyle during mastication

INTRODUCTION

The purpose of this experimental study was to demonstrate the stress patterns arising in the region of the mandibular condyle during mastication.

MATERIAL AND METHOD

Stress analysis was performed using reflection photoelasticity to demonstrate deformation occurring on the surface of the mandible. The rami of three fresh dentate human mandibles were coated with a shell of photoelastic resin. Using a novel loading device, these mandibles were then subjected to external forces (muscular traction, resultant mandibular forces and intra-articular reaction force) reproducing a unilateral biting task between the first right molars. Deformations were measured from the working side.

RESULTS

The trace of isostatic lines from the isoclinic fringes revealed major differences in stress distributions between the three mandibles. These differences were attributed to differences in shape between the three mandibles. Conversely, we consistently found compressive stress patterns along the posterior border of the ramus and tensile stress patterns along the anterior border of the ramus and in the zone situated below the siqmoid notch.

CONCLUSION

These findings suggest that during this particular task, the mandible is subjected to sagittal forces which tend to straighten the mandibular angle. This implies that new concepts are needed for the positioning of osteosynthesis plates in the condylar region, close to the tensile strain lines, as has been recommended also for other parts of the mandible when applying semi-rigid internal fixation.

A comparative evaluation of osteosynthesis with lag screws, miniplates, or Kirschner wires for mandibular condylar process fractures

PURPOSE

This study compared the clinical and radiologic outcomes of open treatment of mandibular condylar process fractures using lag screws, miniplates, or Kirschner wires.

PATIENTS AND METHODS

Open reduction and internal fixation was performed for severely displaced or dislocated mandibular condylar process fractures in 23 patients (26 fractures) using Eckelt lag screws, in 10 patients (10 fractures) using Kirschner wires, and in 21 patients (22 fractures) using miniplates. Clinical and radiologic evaluations were made 6 months postoperatively and at final follow-up (mean, 18.4 months; range, 7 to 106 months). Radiologic evaluation included accuracy of reduction of the fractured condylar processes and changes in ramus height.

RESULTS

Most fractured condylar processes (approximately 90%) were repositioned precisely in all groups. A shortening of the ramus of more than 5 mm was observed significantly more frequently (P <.05) in the miniplate group than in the lag screw group at 6 months. The condyles were severely resorbed in 2 or 3 patients in each group. All of these patients were associated with malunion, and partial bone resorption of the condyles was seen during the first 6 months. The relation between reduction or screw position and bone healing in patients treated with lag screws indicated that correct reduction and screw insertion allowed normal bone healing. The patients in all groups showed satisfactory clinical results. No significant intergroup differences were noted in maximum mouth opening and laterotrusion. However, deviation during mouth opening was significantly greater (P <.05) in cases treated with miniplates than with lag screws.

CONCLUSION

Lag screw osteosynthesis may be more advantageous for restoration of ramus height than miniplates or Kirschner wires.

Surgical complications with open treatment of mandibular condylar process fractures

PURPOSE

This study assessed the surgical complications after open treatment for fractures of the mandibular condylar process.

PATIENTS AND METHODS

A total of 178 patients with unilateral fractures of the mandibular condylar process, 85 treated closed and 93 treated open, were included in this study. A tabulation of surgical findings and intraoperative and postoperative complications was prospectively performed. Standardized animating facial photographs were obtained at several postsurgical intervals and were examined and scored by a prosthodontist and an orthodontist for signs of facial nerve palsy and the quality of the surgical scar. Standard statistical methods were used to assess differences between open and closed treatment groups.

RESULTS

There were very few intraoperative or postoperative complications. At the 6-week point, 17.2% of patients treated open had some weakness of their facial nerve. This had resolved by 6 months. The scars were judged either wide or hypertrophic in 7.5% of cases.

CONCLUSIONS

Based on this study, surgical complications of open treatment of condylar process fractures that lead to permanent dysfunction or deformity are uncommon.

Open treatment of condylar process fractures: assessment of adequacy of repositioning and maintenance of stability

PURPOSE

This study was designed to determine how well fractured condylar processes were reduced and the stability of the internal fixation in a group of patients whose fractures were treated by open reduction.

PATIENTS AND METHODS

Sixty-one patients treated by open reduction and internal fixation for unilateral condylar process fractures were studied prospectively using Towne's and panoramic radiographs. The radiographs were made before surgery, and immediately, 6 weeks, and 6 months postoperatively. The images were traced and digitized, and the position of the fractured condylar process was statistically compared with the position of the nonfractured condylar process in both the coronal and sagittal planes. Additionally, 2 observers examined the images and assessed these same 2 factors.

RESULTS

After surgery, the difference in position between the fractured and nonfractured sides averaged less than 2 degrees (not significantly different), indicating good reduction of the fractures. However, subsequently, between 10% and 20% of condylar processes had postsurgical changes in position of more than 10 degrees.

CONCLUSIONS

This study showed that it is possible to anatomically reduce the fractured condylar process, but changes in position of the condylar fragment may then result from a loss of fixation.

Utilization of panoramic radiographs to evaluate short-term complications of mandibular fracture repair

OBJECTIVES/HYPOTHESIS

Detection of complications after mandibular fracture repair is generally based on the clinical examination. However, postoperative evaluation of the patient often includes imaging of the repaired mandible. At our institution, the majority of patients with mandibular fracture have had at least one panoramic mandible radiograph taken postoperatively. The purpose of this study was to assess whether these radiographic studies contributed to detection of complications and thereby had an impact on the clinical course of the patient.

STUDY DESIGN

Retrospective review.

METHODS

The available medical records over a 5-and-a-half-year period of all patients who were treated at our institution for a fractured mandible were reviewed. Patients included in the study were those who were followed for at least 2 months and two postoperative visits.

RESULTS

Our series of 289 patients included 25 patients with complications. Of these patients, 24 had postoperative panoramic radiographs. All of the complications were discovered based on history and physical examination. In six of the patients with complications, the panoramic radiograph was suspicious for a complication. There were five false-positive studies of the 240 postoperative studies performed in patients without complications. No complications were diagnosed based on radiography.

CONCLUSIONS

After surgical treatment of mandibular fractures, panoramic radiographs add little to the physical examination and history toward the detection of complications. We believe that panoramic radiographs need not be used routinely, but may be reserved for patients who have complaints or physical findings suggestive of complications.

Clinical and radiological evaluation following surgical treatment of condylar neck fractures with lag screws

It was the purpose of this study to evaluate the outcome of lag screw osteosynthesis in severely displaced fractures or fracture dislocations of the mandibular condyle as well as intra- and postoperative complications of this technique. From 1980 to 1996 a total of 492 patients with condylar fractures were treated with lag screw osteosynthesis. Clinical and radiological follow-ups were carried out in 230 patients with severely displaced fractures or fracture dislocations of the mandibular condyle. The period between surgery and follow-up was between 6 months and 2 years. The majority of the clinical results were satisfactory presumably due to the anatomically exact reduction of the fragment (93.4%). Extreme anatomic variations of the mandible (5.8%) and incorrect application of the technique (8.8%) resulted in reduced functional stability of lag screw osteosynthesis. Insufficient fragment reduction and postoperative complications (such as wound infection) entailed restriction of mandibular mobility and arthrotic deformations were seen as persistent radiological irregularities of the mandible. It has been possible to avoid complications and to achieve favourable functional results in complicated fractures of the mandibular condyle by applying strict indications for lag screw osteosynthesis and by considering the individual anatomical peculiarities.

2D-finite element analyses and histomorphology of lag screws with and without a biconcave washer

For osteosynthesis and for bone transplant fixation in particular, a lag screw with a biconcave washer, the so called "Anchor Screw" (AS) has been introduced in maxillo-facial surgery. Using 2D-finite element analysis (FEA), the v. Mises and the circumferential stresses induced in underlying bone by this AS are analysed and compared to those under a conventional lag screw. The stress distributions below the biconcave washer of the AS were correlated with histomorphological bone reactions after AS osteosynthesis in two tumor patients, retrieved 12 weeks and 19 months after tumor surgery, respectively. Depending on the thickness of cortical bone, the v. Mises stress concentrations below the biconcave washer were lower than under the head of the conventional lag screw (CLS), but with a higher stress maximum concentrated around the rim of the washer. The circumferential stresses were only half as high around the AS, and thus the deformation of bone was reduced. As predicted by FEA, histology showed microcrack formation, but then after minimal resorption, remodelling of bone below the biconcave washer. Stable osteosynthesis could be demonstrated by bony union already after 12 weeks, and, while bone remodelling continued in the healed osteotomy, it had decreased around the screws after 19 months. It can be concluded from the biomechanical principles and the histomorphological findings that the AS appears superior to the CLS.

Endoscopically assisted mandibular subcondylar fracture repair

The endoscope has been widely used in aesthetic surgery in recent years, but rarely has it been used in cases of facial trauma. From July of 1996 to December of 1996, the endoscope was used successfully to assist in the repair of mandibular subcondylar fractures in eight patients (five men and three women). Their ages ranged from 15 to 60 years with an average age of 31 years. Six of the patients had other associated mandibular fractures including angular, parasymphyseal, and contralateral subcondylar fractures. A 4.0-mm, 30-degree telescope was introduced to visualize the fracture site by means of an intraoral incision over the ascending ramus. A miniplate was used to stabilize the fracture site with the help of a percutaneous trocar. Intermaxillary fixation was applied for 3 to 6 days. Functionally, all patients returned to normal range of motion within 8 weeks. A slight deviation to the trauma site was noted on maximal opening in three patients, but this condition returned to normal 3 months after surgery. There was no facial palsy or lip numbness. The benefits of the endoscopic approach include not only the provision of better visualization and precise anatomic alignment of bony segments but also the avoidance of large facial scars and facial nerve injuries.

Open reduction without fixation of dislocated condylar process fractures: long-term clinical and radiologic analysis

PURPOSE

This study evaluates the long-term results of open reduction without fixation for displaced fractures of the condylar process.

PATIENTS AND METHODS

Clinical and radiologic examinations were performed on 27 patients with 29 operated joints an average of 6.7 years postoperatively. The postoperative result was evaluated on the basis of occlusal and joint function, as well as radiographic assessment of condylar changes.

RESULTS

Clinically, satisfactory results were achieved. Radiologically, despite correct intraoperative alignment of the fractured segments, a slight medial deviation of the condylar process was found on the posteroanterior radiograph. However, in only two cases was a 20-degree deviation observed. On final follow-up, 48% of the cases had a normal condylar configuration radiologically, and in the remaining cases, normal function was established even though there were condylar changes. Fully exposed and devascularized condylar processes generally showed more severe changes than those in which partial vascularization was maintained.

CONCLUSION

The surgical management described enables a satisfactory outcome to be achieved with dislocated condylar process fractures.

Modified osteosynthesis for condylar neck fractures in atrophic mandibles

A fixation system combining both plate and lag screw osteosynthesis for condylar neck fractures of the mandible is described. The currently available device is adapted in that the lag screw is inserted in the lateral cortical bone of the condylar segment instead of the cancellous bone alone.

A multicentre audit of unilateral fractures of the mandibular condyle

OBJECTIVE

To audit a series of isolated unilateral fractures of the mandibular condyle treated in a number of units in the United Kingdom.

DESIGN

Prospective confidential multicentre audit with review by a single external examiner between July 1993 and January 1994.

SETTING

Nine Maxillofacial units. Pro-formas were alphanumerically coded. Units are referred to by code letter.

SUBJECTS

142 patients with fractures of the mandibular condyle.

MAIN OUTCOME MEASURES

Pain, crepitus, interincisal opening, mandibular deviation on movement, occlusion and posteroanterior and lateral radiographic analysis by a single examiner.

RESULTS

Of the 142 patients, 135 over the age of 12 years had unilateral condylar fractures. Seventy-three attended appointments at both 6 and 12 weeks. Forty-one had identifiable symptoms attributable to the injury at 12 weeks, and most of these had fracture displacements or dislocations which had not been openly reduced. There was a 50-85% positive correlation between radiographic findings of the first clinician and the external auditor. Open reduction and internal fixation was uncommon.

CONCLUSIONS

Follow-up studies of trauma patients are difficult because of poor attendance. Fractures of the mandibular condyle should be treated by specialists in the management of facial fractures. Accurate clinical and radiographic diagnosis is more difficult than commonly supposed. Fracture displacements and dislocations have a suboptimal outcome in nearly 30% of cases. More should be spent to improve care of these patients. A consensus on objective indicators of satisfactory outcome is needed to establish a 'gold standard' and close the audit loop.

Lag-screw fixation of mandibular parasymphyseal and angle fractures

OBJECTIVE

This study was carried out to evaluate clinical and radiologic results after lag-screw fixation (LSF) of mandibular parasymphyseal and angular fractures was performed.

STUDY DESIGN

Seven angle and 17 parasymphyseal fractures in 23 adult patients with mandibular fractures were treated by transoral reduction and LSF. Clinical and radiologic examinations were undertaken during a 3-month follow-up period

RESULTS

All parasymphyseal fractures and four angular fractures went to good bone union after surgery. Infectious complications occurred in two patients with parasymphyseal fractures. These resolved with simple procedures. Three angular fractures needed refixing because of instability. Slight occlusal adjustment was needed in five patients. Postoperative neurosensory deficits were transient in every case in which they were seen.

CONCLUSIONS

LSF of mandibular parasymphyseal fractures is a practical and effective way of fixing such fractures internally. It leads to good bone healing without permanent neurosensory deficit or increased risk of malocclusion. In mandibular angle fractures LSF is likely to be too technique-sensitive to allow its extensive use.