Zygomatic fractures: comparison of methods of internal fixation

We have analyzed different methods of internal fixation of simple displaced fractures of the zygoma in an attempt to define the simplest method(s) of achieving postreduction stability. Twenty-five combinations of interfragmentary wiring and miniplate and screw fixation of fractured zygomas on human skulls were compared for postreduction rotational stability against stresses simulating the muscular forces that act to displace the zygoma once it has been reduced. Analysis of the data suggests that while three-point fixation using either miniplates or interosseous wires allows for virtually no displacement, two-point fixation and in some cases one-point fixation provide acceptable stability. In general, stable fixation is achieved by methods that involve the use of at least one miniplate and incorporate the frontozygomatic suture line as one of the points of fixation.     

Treatment of mandibular angle fractures with a matrix miniplate: a preliminary report

Mandibular angle fractures are technically challenging, and a spectrum of techniques for treatment of these fractures has been proposed in the literature. Currently, fixation with one or two miniplates has become a widely accepted method of providing internal fixation and eliminating the need for postoperative maxillomandibular fixation. In this study, the utility of a single 2.0-mm matrix miniplate for mandibular angle fracture management was examined. In a laboratory biomechanical analysis, the overall stability of the single 2.0-mm matrix miniplate compared favorably with two 2.0-mm miniplates in a simulated fracture setting. The matrix miniplate demonstrated an overall better intrinsic stability, more resistance to out-of-plane fracture movement, and a higher load tolerance when motion out-of-plane was challenged. Clinically, the matrix miniplate performed well. In a series of 22 consecutive patients, there were no cases of nonunion, malunion, or plate failure. Two patients developed infection that was managed in both cases by drainage with maintenance of the miniplate. Both went on to full union. These results compare very favorably to previously published series using one or two miniplates.     

Biomechanical comparison of locking plate and crossing metallic and absorbable screws fixations for intra-articular calcaneal fractures

The locking plate and percutaneous crossing metallic screws and crossing absorbable screws have been used clinically to treat intra-articular calcaneal fractures, but little is known about the biomechanical differences between them. This study compared the biomechanical stability of calcaneal fractures fixed using a locking plate and crossing screws. Three-dimensional finite-element models of intact and fractured calcanei were developed based on the CT images of a cadaveric sample. Surgeries were simulated on models of Sanders type III calcaneal fractures to produce accurate postoperative models fixed by the three implants. A vertical force was applied to the superior surface of the subtalar joint to simulate the stance phase of a walking gait. This model was validated by an in vitro experiment using the same calcaneal sample. The intact calcaneus showed greater stiffness than the fixation models. Of the three fixations, the locking plate produced the greatest stiffness and the highest von Mises stress peak. The micromotion of the fracture fixated with the locking plate was similar to that of the fracture fixated with the metallic screws but smaller than that fixated with the absorbable screws. Fixation with both plate and crossing screws can be used to treat intra-articular calcaneal fractures. In general, fixation with crossing metallic screws is preferable because it provides sufficient stability with less stress shielding.     

Physiological loading of the mandibular osteosynthesis: development of an improved mandibular load simulator]

Loading conditions physiologically approximating those acting on the normal masticatory system were incorporated into a new mandibular load simulator. Separate tension wires attached to each ramus of the mandible simulated the resultant force vectors of the masticatory musculature. The muscle insertion points were chosen in accordance with the anatomical situation, and the maximum in vivo forces acting on the joint. In a first application, the stability of a 2.4 mm LC-WDCP was compared with that of a 2.7 mm EDCP in plastic mandible models. It was found that under largely physiological loading, the 2.4 mm LC-EDCP exerted a stabilizing effect similar to that of a 2.7 mm EDCP. Although of smaller dimensions, the 2.4 mm LC-EDCP appears to enable an osteosynthesis of similar stability in the treatment of fractures of the mandibular angle.     

Bending but not breaking the supraorbital bar

Surgical bending or contouring of the supraorbital bar may cause inadvertent fractures during craniofacial surgery. Wires may be placed in the bony segments themselves to facilitate reshaping with the Tessier rib bender. The wires are especially helpful in stabilizing the more acute curve at the lateral orbital rim.     

Treatment of mandible fractures using low-profile titanium miniplates: preliminary study.

This study evaluated the short-term results of patients treated with low-profile titanium miniplates for fractures of the mandible. Thirty-one fractures of the mandible in 23 patients were treated by open reduction and internal fixation using thin, low-profile miniplates and 1.3-mm self-threading screws. Duration of intermaxillary fixation ranged from 0 to 25 days. Patients were evaluated for complications during a follow-up period ranging from 6 to 24 months. Seven patients (30.4 percent) experienced complications. These included infection (n = 1), premature occlusal contact (n = 1), wound dehiscence (n = 1), temporomandibular joint disorder (n = 1), and paresthesia (n = 3). All complications were minor and adequately managed with incision and drainage, medication, and elastic traction. Low-profile titanium miniplates can be adequately used for internal fixation in selective mandibular fractures. Advantages of these types of plates include comfort due to the thinness of miniplates and ease of application.     

Management of the medial canthal tendon in nasoethmoid orbital fractures: the importance of the central fragment in classification and treatment

The medial canthal tendon and the fragment of bone on which it inserts ("central" fragment) are the critical factors in the diagnosis and treatment of nasoethmoid orbital fractures. The status of the tendon, the tendon-bearing bone segment, and the fracture pattern define a clinically useful classification system. Three patterns of fracture are appreciated: type I--single-segment central fragment; type II--comminuted central fragment with fractures remaining external to the medial canthal tendon insertion; and type III--comminuted central fragment with fractures extending into bone bearing the canthal insertion. Injuries are further classified as unilateral and bilateral and by their extension into other anatomic areas. The fracture pattern determines exposure and fixation. Inferior approaches alone are advised for unilateral single-segment injuries that are nondisplaced superiorly. Superior and inferior approaches are required for displaced unilateral single-segment injuries, for bilateral single-segment injuries, and for all comminuted fractures. Complete interfragment wiring of all segments is stabilized by junctional rigid fixation. All comminuted fractures require transnasal wiring of the bones of the medial orbital rim (medial canthal tendon-bearing or "central" bone fragment). If the fracture does not extend through the canthal insertion, the canthus should not be detached to accomplish the reduction.     

Infraorbital nerve injury associated with zygoma fractures: documentation with neurosensory testing

Persistent sensibility abnormalities after correction of zygoma fractures indicate injury to the infraorbital nerve and may produce pain. To investigate this, a retrospective study of 25 patients who had undergone surgical correction of a zygoma fracture was performed. Bilateral neurosensory measurements were obtained with the Pressure-Specified Sensory Device (Sensory Management Services, Baltimore, Md.). Seven of the 25 patients had required orbital floor reconstruction. Each patient had undergone fracture correction at least 6 months earlier and was interviewed, at the time of sensibility testing, regarding symptoms related to the fracture. The data were evaluated by a blinded examiner, from a separate clinical facility, who attempted to predict the side of the fracture and the degree of zygoma displacement on the basis of measurements of sensibility of the paranasal, upper lip, and zygomaticotemporal areas. Seventy-six percent of patients demonstrated abnormal sensibility on the side of the zygoma fracture, compared with the contralateral side. Sensibility was abnormal for 100 percent of the patients who required orbital floor reconstruction. Seventy-four percent of patients with abnormal sensibility reported symptoms related to the fracture. Eighty percent of the zygoma fractures were correctly identified, with respect to the side of the fracture, by the blinded examiner on the basis of the neurosensory measurements alone (p < 0.005). Predictions proved correct for 91 percent of the patients with widely displaced fractures and none of the patients with nondisplaced fractures. The results of this study suggest that neurosensory testing is an important clinical adjunct for the evaluation of patients with facial pain or dysesthesia after facial fracture reconstruction. The results suggest the need to develop algorithms for the diagnosis and treatment of trigeminal nerve injuries after craniofacial trauma. This approach could also be applicable to dysesthesia or pain after aesthetic facial surgical procedures.     

Intraoral approach for reduction malarplasty: a simple method

Young Korean women with prominent zygoma may experience stress in daily life because the Oriental physiognomy often associates prominent zygoma with bad luck. Moreover, prominent zygoma in a wide Oriental face has the effect of making a person appear older and stubborn. Zygomatic reduction is often necessary to relieve stress from self-consciousness about facial appearance and to obtain younger and softer features. As such, most zygomatic procedures are cosmetic; therefore, an entirely intraoral approach with no skin incision is desirable. The current operative method of zygomatic reduction consists of two steps. The zygomatic body and arch are exposed through a mucoperiosteal incision from the maxillary canine to the first molar area. The first step is to grind and file the zygomatic body. The second step is made on the zygomatic arch. Using an oscillating saw, a partial-thickness osteotomy is made just posterior to the orbital rim, and a full-thickness osteotomy is made just anterior to the articular tubercle of the zygomatic arch. Light pressure on the posterior part of the arch produces a greenstick fracture of the anterior osteotomy site and a complete fracture of the posterior osteotomy site, resulting in inward repositioning of the zygomatic arch. This method of zygomatic reduction is simple, easy, effective, and leaves no conspicuous scars on the face.     

The use of miniplates in craniomaxillofacial surgery

Miniplates were used in craniomaxillofacial surgery for fixation in the skull, maxilla, and/or mandible in 74 patients with minimal or no intermaxillary wiring. Procedures included forehead and orbital repositioning, frontofacial advancement, Le Fort III and particularly Le Fort I osteotomies, as well as mandibular osteotomies and fracture repair. The miniplates provided stable fixation and, compared with other techniques, improved airway safety. The complication rate was low: there were no infections, but two plates (1 percent) became exposed in the buccal sulcus. Although application of miniplates lengthened surgery and increased the cost of the procedure, the savings in intensive care monitoring more than offset these costs. The stability of fixation minimizes the opportunity to reposition the fragments postoperatively with training elastics. Therefore, meticulous technique is mandatory, with particular emphasis on passive fitting of the plates and precise drilling of screw holes.     

Toward CT-based facial fracture treatment

Facial fractures have formerly been classified solely by anatomic location. CT scans now identify the exact fracture pattern in a specific area. Fracture patterns are classified as low, middle, or high energy, defined solely by the pattern of segmentation and displacement in the CT scan. Exposure and fixation relate directly to the fracture pattern for each anatomic area of the face, including frontal bone, frontal sinus, zygoma, nose, nasoethmoidal-orbital region, midface, and mandible. Fractures with little comminution and displacement were accompanied by subtle symptoms and required simple treatment; middle-energy injuries were treated by standard surgical approaches and rigid fixation. Highly comminuted fractures were accompanied by dramatic instability and marked alterations in facial architecture; only multiple surgical approaches to fully visualize the "buttress" system provided alignment and fixation. Classification of facial fractures by (1) anatomic location and (2) pattern of comminution and displacement define refined guidelines for exposure and fixation.     

Biomechanical Comparison of Different Stabilization Constructs for Unstable Posterior Wall Fractures of Acetabulum. A Cadaveric Study

Purpose

Operative treatment of unstable posterior wall fractures of acetabulum has been widely recommended. This laboratory study was undertaken to evaluate static fixation strength of three common fixation constructs: interfragmentary screws alone, in combination with conventional reconstruction plate, or locking reconstruction plate.

Methods

Six formalin-preserved cadaveric pelvises were used for this investigation. A posterior wall fracture was created along an arc of 40–90 degree about the acetabular rim. Three groups of different fixation constructs (two interfragmentary screws alone; two interfragmentary screws and a conventional reconstruction plate; two interfragmentary screws and a locking reconstruction) were compared. Pelvises were axial loaded with six cycles of 1500 N. Dislocation of superior and inferior fracture site was analysed with a multidirectional ultrasonic measuring system. Results: No statistically significant difference was found at each of the superior and inferior fracture sites between the three types of fixation. In each group, the vector dislocation at superior fracture site was significantly larger than inferior one.

Conclusions

All those three described fixation constructs can provide sufficient stability for posterior acetabular fractures and allow early mobilization under experimental conditions. Higher posterior acetabular fracture line, transecting the weight-bearing surface, may indicate a substantial increase in instability, and need more stable pattern of fixation.     

Reduction malarplasty through an intraoral incision: a new method

Until recently, osteotomies and surgeries to reposition prominent zygoma have been performed by means of a coronal incision or intraoral and preauricular incisions. Such incisions have penalties such as scars, the possibility of facial nerve injury, and long operative times. After reflecting on their past experiences with facial bone surgery, the authors developed an alternative approach. In this method, the cheekbone protrusion is corrected by performing an osteotomy and repositioning through an intraoral incision only. During the past 3 years, the authors have operated on 23 patients with malar prominences. The amount of bone to be removed is determined by preoperative interviews, physical examinations, and x-rays. Intraoral incisions provide access to the zygomatic body and lateral orbital rim. After L-shaped osteotomies (two parallel vertical and one transverse osteotomy at the medial part of the zygomatic body), the midsegment is removed. The posterior portion of the zygomatic arch was approached through the medial aspect and was outfractured using a curved osteotome. After completing the triple osteotomy, the movable zygomatic complex was reduced medially and fixed with miniplates and screws on the zygomaticomaxillary buttress. The patients were followed for 9.5 months, with acceptable results and few complications. The authors conclude that this technique is an effective and safe method of reduction malarplasty.     

Acromion-fixation of glenoid components in total shoulder arthroplasty

Successful design of components for total shoulder arthroplasty has proven to be challenging. This is because of the difficulties in maintaining fixation of the component that inserts into the scapula; i.e., the glenoid component. Glenoid components that are fixated to both the glenoid and acromion (a long process extending medially on the dorsal aspect of the scapula) have the possible advantage of greater stability over those that are fixated to the glenoid alone. In this study, a finite element analysis is used to investigate whether or not acromion fixation is advantageous for glenoid components. Full muscle loading and joint reaction forces are included in the finite element model. Reflective photoelasticity of five scapulae is used to obtain experimental data to compare with results from the finite element analysis, and it confirms the structural behaviour of the finite element model. When implanted with an acromion-fixated prosthesis, it is found that high unphysiological stresses occur in the scapula bone, and that stresses in the fixation are not reduced. Very high stresses are predicted in that part of the prosthesis which connects the acromion to the glenoid. It is found that the very high stresses are partly in response to the muscle and joint reaction forces acting at the acromion. It is concluded that, because of the relatively high forces acting at the acromion, fixation to it may not be the way forward in glenoid component design.     

Osteotomy to treat malocclusion following reconstruction of the mandible with the free fibula flap

Malocclusion may result after free fibula flap reconstruction of the mandible, because of inadequate positioning of the temporomandibular joint, inaccurate contouring of the reconstruction plate, or subsequent fracture of a miniplate. Factors that alter the vascularity of the transplanted fibula may also result in a delayed presentation of malocclusion. Seven cases are presented, in which primary surgical treatment consisted of segmental mandibulectomy and reconstruction with a free fibula osteoseptocutaneous flap. Fixation was achieved with a reconstruction plate in five cases and a miniplate in two cases. Malocclusion was corrected with an osteotomy performed at the junction of the fibula and the native mandible. The new osteotomy sites were fixed with miniplates and maintained with intermaxillary fixation. Complete bony union was achieved at the osteotomy sites. The correction of malocclusion was successful in all cases, and all patients have resumed a normal diet. This report demonstrates that osteotomy and realignment of the mandible are effective for the secondary correction of malocclusion after mandibular reconstruction with the free fibula osteoseptocutaneous flap.     

Biodegradable Implants in the Fixation of Physeal Fractures in Cats and Dogs

In a preclinical and a clinical study physeal fractures of cats and dogs were fixated with biodegradable implants. The preclinical part consisted of 4 cats with experimental physeal fractures of the distal femurs and the clinical part of 6 cats and 8 dogs with different physeal fractures. All fractures were fixated with selfreinforced polyglycolic acid (PGA) implants of different sizes. No external support was applied after the fixation. All cats and dogs used their operated legs during the first postoperative week and they could walk without lameness in 6 weeks. The fracture healed without delay or malformations. The retardations of the growth of the physeal regions were considered minimal.     

Experimental and clinical results of new advances in the treatment of facial trauma

Theoretical considerations and photoelastic and mechanical experiments showed us the progression from metal wires to metal plates in different systems. In the midface there is no question about stabilization by miniplate systems. For mandibular fracture treatment, there is a discussion going on at present about the use of stable maxisystems versus less stable minisystems. Our clinical experience of 15 years indicates that there is no further demand for strict stable fixation of mandibular fractures, and we were encouraged to use less stable systems with similar good results, as our follow-up and statistical evaluation showed. To continue the simplification of osteosynthesis methods we are performing experiments with resorbable materials. Early results show fracture healing comparable with that found with plate-and-screw systems. Our clinical experience has shown that there is no longer any question about the ability of stable fracture treatment by means of osteosynthesis. However, there still is the question of how functional such fracture treatment might be.     

Blow-in fractures of the orbit

A blow-in fracture is an inwardly displaced fracture of the orbital rim or wall resulting in decreased orbital volume. The purpose of this study is to classify orbital blow-in fractures, describe the distinguishing clinical and radiologic features, and review the result of treatment. The series consists of 41 patients with blow-in fractures (34 males and 7 females). The mean age of the patients was 36 years. All were treated between 1979 and December of 1986 at Sunnybrook Medical Centre in Toronto. Clinical features of blow-in fractures were primarily related to the decrease in volume of the orbital cavity. Proptosis was a consistent finding, and in 27 percent of patients, the globe was further displaced in a coronal plane. Restricted ocular motility and diplopia were documented in 24 and 32 percent of patients, respectively. Fracture fragments displaced into the orbit resulted in globe rupture in 12 percent of patients, superior orbital fissure syndrome in 10 percent, and optic nerve injury in 1 patient. Blow-in orbital injuries were classified as pure fractures, consisting of an isolated blow-in of a segment of the roof, floor, or walls, or impure fractures, where the orbital rim itself was disrupted. In all cases, early decompression of the orbit and open reduction of fractures was necessary. Late sequelae of blow-in fractures were primarily related to injuries of intraorbital contents. Twelve percent of patients underwent enucleation and 8 percent reported persistent diplopia. Despite the presence of superior orbital fissure syndrome and complete ophthalmoplegia in 10 percent of patients, early orbital decompression resulted in resolution of nerve palsies in all but one patient.     

Aesthetic and restorative midface lifting with hand-carved,expanded polytetrafluoroethylene orbital rim implants

The midface lift represents an important advance in aesthetic and reconstructive surgery. However, the need for reliable fixation along the orbital rim has been a significant challenge. Furthermore, volume is needed at the orbital rim, to compensate for long-term remodeling of the bone of the orbital rim and malar face. A technique using a hand-carved, expanded polytetrafluoroethylene implant that is permanently anchored to the orbital rim with titanium microscrews, creating a site for fixation of the advanced midface soft tissues, was developed. This report presents a retrospective, uncontrolled, case series of 41 consecutive patients who underwent transconjunctival midface operations with these implants, and it addresses a variety of midface aesthetic and reconstructive deficits. Only patients with at least 6 months of follow-up data were included in the study. To date, significant complications have been limited. The complications included two cases of implant palpability, with only one requiring surgical modification. One patient underwent implant removal because of skin breakdown and infection related to recurrent squamous cell carcinoma. One patient required revisional lateral canthoplasty for reasons of symmetry. On the basis of this series, hand-carved, expanded polytetrafluoroethylene implants seem to have significant advantages, compared with previously available orbital rim implants. These advantages include the ability to easily modify the implant for the individual anatomical needs, the creation of a secure anchor for fixation of advanced midface soft tissues, excellent tolerance of the implant material, and the ability to place the implant with limited exposure. The greatest disadvantage is the need for the surgeon to carve the implant, which requires time and carving skill. Despite this limitation, the technique is promising.     

Effect of meniscus replacement fixation technique on restoration of knee contact mechanics and stability

The menisci are important biomechanical components of the knee. We developed and validated a finite element model of meniscal replacement to assess the effect of surgical fixation technique on contact behavior and knee stability. The geometry of femoral and tibial articular cartilage and menisci was segmented from magnetic resonance images of a normal cadaver knee using MIMICS (Materialise, Leuven, Belgium). A finite element mesh was generated using HyperWorks (Altair Inc, Santa Ana, CA). A finite element solver (Abaqus v6.9, Simulia, Providence, RI) was used to compute contact area and stresses under axial loading and to assess stability (reaction force generated during anteroposterior translation of the femur). The natural and surgical attachments of the meniscal horns and peripheral rim were simulated using springs. After total meniscectomy, femoral contact area decreased by 26% with a concomitant increase in average contact stresses (36%) and peak contact stresses (33%). Replacing the meniscus without suturing the horns did little to restore femoral contact area. Suturing the horns increased contact area and reduced peak contact stresses. Increasing suture stiffness correlated with increased meniscal contact stresses as a greater proportion of tibiofemoral load was transferred to the meniscus. A small incremental benefit was seen of simulated bone plug fixation over the suture construct with the highest stiffness (50 N/mm). Suturing the rim did little to change contact conditions. The nominal anteroposterior stiffness reduced by 3.1 N/mm after meniscectomy. In contrast to contact area and stress, stiffness of the horn fixation sutures had a smaller effect on anteroposterior stability. On the other hand suturing the rim of the meniscus affected anteroposterior stability to a much larger degree. This model emphasizes the importance of the meniscus in knee biomechanics. Appropriate meniscal replacement fixation techniques are likely to be critical to the clinical success of meniscal replacement. While contact conditions are mainly sensitive to meniscus horn fixation, the stability of the knee under anteroposterior shear loads appeared to be more sensitive to meniscal rim fixation. This model may also be useful in predicting the effect of biomaterial mechanical properties and meniscal replacement shape on knee contact conditions.