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PubMed2003

[Experimental and clinical study of the stability of an osteosynthesis plate for the atrophic mandible].

BACKGROUND: The high rate of complications led us to develop a new osteosynthesis plate for the treatment of the fractured atrophied mandible. The development of the new so-called pencil-bone plate is based on the 2.0 mini-plate system manufactured by the Medartis Company. MATERIAL AND METHODS: Finite elements (FE) analysis of the new plate as well as flexibility experiments were undertaken, and 14 patients with 16 fractures of the atrophied mandible were treated with the pencil-bone plate between October 2000 and November 2001. RESULTS: The results clearly show that the pencil-bone plate reacted in both the FE model and the static flexibility experiment in a more stable way than a standard 2.0 plate. In 13 patients, healing proceeded without serious complications; all of the patients showed subjective, nearly unchanged chewing, speaking, and swallowing abilities and no complications occurred when wearing dentures. One patient underwent surgical intervention after a new trauma. CONCLUSION: The clinical outcome of the treated fractures confirmed the experimental results, which proved the high stability of the plate in the area of the fracture site. Due to the mini-plate format the intraoral application of the plate is possible without problems. The intraoral access allows rapid operation followed by a minimum of morbidity. A great advantage of the small dimension system is the unrestricted wearing of dentures after the application.

Aged↗
PubMedDate not supplied

A biomechanical comparison of 7-hole 3.5 mm broad and 5-hole 4.5 mm narrow dynamic compression plates.

Seven-hole 3.5 mm broad and 5-hole 4.5 mm narrow dynamic compression plates were applied to paired canine cadaveric tibias in a stable fracture model. Paired tibias were tested to acute failure in rotation and four-point bending, and to fatigue failure in four-point bending. Resistance to screw pullout was measured for three 3.5 mm cortical screws and two 4.5 mm cortical screws inserted in the configurations of the bone plates. All plate-bone systems failed by fracture of the bone through a screw hole. The 3.5 mm plate-bone system was stronger in acute failure in rotation and in four-point bending. There was no difference in stiffness, and no difference in the number of cycles to failure in fatigue testing. Three 3.5 mm screws had greater resistance to pullout than two 4.5 mm screws. Results indicate that the 7-hole 3.5 mm broad dynamic compression plate has a biomechanical advantage over the 5-hole 4.5 mm narrow dynamic compression plate.

Animals↗
PubMed1993

Holding power of metallic plates in cancellous bone. An experimental study on rabbits with polymethyl methacrylate as supporting material.

The holding power of a metallic device in cancellous bone was tested in sixteen rabbits (n = 16). The device was fixed with the support of polymethyl methacrylate. The fixation firmness was studied radiologically and by measuring the bonding strength. The mean value of the bonding strength was 485 N (n = 6) at 6 weeks, and 557 N (n = 8) at 12 weeks.

Animals↗
PubMed1998

LC-DC plating with bone graft in posttraumatic nonunions in the middle third of the clavicle.

Nonunions and malunions of the clavicle are uncommon but can be disabling, causing pain, limitation of shoulder motion or local brachial plexus compression. Reconstructive procedures are focused on gaining union and restoring functional clavicular anatomy. We would like to present a surgical procedure in which an autologous iliac crest graft and a 3.5 mm low contact-dynamic compression plate (LC-DCP) are used to regain clavicular stability and union. Surgery was performed in all eight patients for symptomatic nonunion. Eight patients treated by this method between 1991-1996 showed clinical and radiological union after an average follow-up time of eight months. All patients were highly satisfied with the surgical result. The advantages of the LC-DCP in the internal fixation of clavicular nonunions with its demanding anatomical and biomechanical characteristics are presented.

Adult↗
PubMedDate not supplied

Rigid fixation with plate and bone graft in failures of intramedullary osteosynthesis for the treatment of diaphyseal nonunion of the femur.

Fractures and diaphyseal nonunion of the femur are normally treated by intramedullary nailing. In cases in which nailing fails, nonunion is treated by reaming of the canal and substitution of the nail with one of a more adequate caliber. Rarely, however, due to unfavorable mechanical conditions or in cases of atrophic nonunion or with scarce vascularization the biological conditions for healing are absent. In cases such as these, nonunion must be treated by rigid internal fixation with a plate, aided by the use of cortical graft on the opposite side. The authors present 7 cases of diaphyseal nonunion of the femur treated between 1994 and 1996 using rigid fixation (plate and graft) as a salvage method, as a result of numerous previous failures in surgery. The results were favorable in all of the cases without complications.

Adult↗
PubMed1993

Hydroxylapatite supported Dacron plugs for repair of isolated full-thickness osteochondral defects of the rabbit femoral condyle: mechanical and histological evaluations from 6-48 weeks.

The early degeneration of neocartilage commonly observed after experimental cartilage repair is attributed in part to the impaired cartilage-bone mechanics caused by an insufficient regrowth of the subchondral bone plate. In order to enhance bone regrowth after cartilage repair Dacron plugs supported by hydroxylapatite were implanted into 3 mm diameter full-thickness defects of both medial femoral condyles in 21 rabbits. In addition, the plug in one knee of each animal was wrapped with autologeous periosteum from the proximal tibia. The repair sites were evaluated at 6, 12, 24, and 48 weeks. Except for the mechanics of the repair site at 24 weeks additional periosteum did not improve the overall results. In specimens with additional periosteum the compression compliance of the repair sites improved gradually from abnormal high to almost normal values at 24 weeks, but were found softened again at 48 weeks. All other repairs were softer than normal cartilage at all time intervals. In all specimens a well-defined but irregularly shaped, subchondral bone plate had developed by 12 weeks. The neocartilage was initially thicker than normal cartilage, but the thickness decreased gradually and reached normal values by 48 months. Neocartilage formation with moderate morphological scores appeared already at 6 weeks, but the scores did not improve with time. High variations in quality of the regenerated tissue, from insufficient regeneration to hyaline-like cartilage, were found at all time intervals, but none of the specimens had developed normal cartilage. Most knees had a low-grade synovitis and some had particle debris.

Animals↗
PubMed1999

Treatment of mandibular angle fractures with a malleable noncompression miniplate.

PURPOSE: This study evaluated the results in patients treated for fractures of the mandibular angle with a single, thin, malleable miniplate designed for use in the midface. PATIENTS AND METHODS: Forty-six patients with 51 fractures of the mandibular angle were treated by open reduction and internal fixation using one noncompression, thin, malleable miniplate and 1.3-mm self-threading screws placed through a transoral incision. No patient was placed into postsurgical maxillomandibular fixation. They were prospectively studied for complications. RESULTS: Seven patients (15.2%) experienced complications. All were considered minor and did not require hospitalization. Three had asymptomatic fracture of the bone plate, but at the time of diagnosis the fracture had already healed and it required no treatment. Two patients had fracture of the bone plate with continued fracture mobility requiring maxillomandibular fixation. Three minor infections occurred requiring intraoral incision and drainage. CONCLUSIONS: The use of this small bone plate for fractures of the angle of the mandible provided adequate fixation in most cases but was associated with an unacceptable incidence of plate fracture. However, the results also indicate that the fixation requirements for angle fractures is less than previously thought.

Adolescent↗
PubMed1987

Intraosseous wire fixation versus rigid osseous fixation of mandibular fractures: a preliminary report.

While wire osteosynthesis has been the accepted modality to use with open reduction of mandibular fractures, several authors have suggested the use of more rigid techniques to achieve the same result while also eliminating adverse effects associated with prolonged maxillomandibular fixation. Few studies have directly compared the two techniques in a prospective manner. The purpose of this paper was to evaluate complications seen with wire osteosynthesis versus a small bone plating system in management of mandibular fractures. The results suggest that small bone plating systems similar to the one used in this study may serve as a suitable alternative to wire osteosynthesis for the management of mandibular parasymphysis, body, and angle fractures. The length of the procedure, the length of hospital stay, and patient comfort were comparable with the two techniques. Factors that may contribute to failure are: location of the fracture, poor patient compliance, length of time from the trauma to the repair, antibiotic choice, and most importantly, operator skill and experience.

Adolescent↗
PubMed1999

Bmp activity establishes a gradient of positional information throughout the entire neural plate.

Bone morphogenetic proteins (Bmps) are key regulators of dorsoventral (DV) patterning. Within the ectoderm, Bmp activity has been shown to inhibit neural development, promote epidermal differentiation and influence the specification of dorsal neurons and neural crest. In this study, we examine the patterning of neural tissue in mutant zebrafish embryos with compromised Bmp signalling activity. We find that although Bmp activity does not influence anteroposterior (AP) patterning, it does affect DV patterning at all AP levels of the neural plate. Thus, we show that Bmp activity is required for specification of cell fates around the margin of the entire neural plate, including forebrain regions that do not form neural crest. Surprisingly, we find that Bmp activity is also required for patterning neurons at all DV levels of the CNS. In swirl/bmp2b(-) (swr(-)) embryos, laterally positioned sensory neurons are absent whereas more medial interneuron populations are hugely expanded. However, in somitabun(-) (sbn(-)) embryos, which probably retain higher residual Bmp activity, it is the sensory neurons and not the interneurons that are expanded. Conversely, in severely Bmp depleted embryos, both interneurons and sensory neurons are absent and it is the most medial neurons that are expanded. These results are consistent with there being a gradient of Bmp-dependent positional information extending throughout the entire neural and non-neural ectoderm.

Animals↗
PubMed1987

Skeletal fixation in digital replantation. Use of the "H" plate.

Many forms of bone fixation have been advocated for use in digital replantation, and successful series have been reported using such methods as intramedullary Kirschner-wire fixation, crossed Kirschner-wires, bone pegs, double-headed screws, and bone plates. Symptomatic nonunions have been rare with these various types of bone fixation. The functional results that have been reported are usually considered good; however, amputation of digits through the proximal phalanges is still a difficult area in which to obtain satisfactory function as measured by proximal interphalangeal joint motion. This may be related to a reluctance on the part of the surgeon to use early mobilization techniques for fear of disrupting marginally stabilized fractures. The "H" plate provided rigid fixation in six patients. This technique promotes earlier mobilization and shows promise of improved functional results.

Amputation, Traumatic↗
PubMed2003

[Aseptic non-union of humeral shaft fractures treated by plating and bone grafting].

PURPOSE OF THE STUDY: Although aseptic non-union of humeral shaft fractures is generally considered to be an exceptional complication, rates in the literature have varied from 1 to 10%. Factors favoring non-union are often related to technical error or inappropriate therapeutic indication. Several types of treatment (orthopedic, locked centromedullary nailing, ascending pinning, plating, external fixation) can be proposed for humeral shaft fractures. In all cases, a precise technique and proper indication are essential for success. We reviewed the cases of 30 patients who underwent surgery for aseptic non-union of humeral shaft fractures between 1995 and 2000. MATERIAL AND METHODS: Mean patient age was 43 years. Oblique and transverse fractures of the middle third of the shaft predominated. All types of treatment had been used but most of the patients had had ascending pinning. All patients were treated with plate fixatin and a cancellous bone graft after identifying the radial nerve. RESULTS: Bone healing was achieved in all patients. Mean delay to healing was 16 weeks with good motion of the shoulder (mean elevation 136 degrees ) and elbow (mean motion 10-130 degrees ). Transient radial paresia recovered spontaneously in two patients. There was one infection. Only two patients complained of a painful arm that was not bothersome for daily activities and did not require long-term analgesia. There were no cases of radial nerve injury. Elbow function improved in 16 patients, was unchanged in 11, and showed limited extension in 3. Shoulder function improved in 15 patients and was unchanged in 15. DISCUSSION: Plate fixation is widely described in the literature for the treatment of humeral non-union. The main complications of this treatment are radial palsy and infection, reported in 5% of the series. Several recent reports have therefore advocated locked nailing or external fixation with an Ilizarov device but these techniques are difficult to use and have their own risks of complications. It is difficult to block rotation and the nail may injure the rotator cuff. Pin tract infection, nerve injury, and prolonged external fixation are other disadvantages. We therefore recommend screw plate fixation with a cancellous bone graft. Our good results combined with the very low rate of complications argue in favor of this therapeutic option.

Accidental Falls↗
PubMed1988

Tissue reaction to implant corrosion in 38 internal fixation devices.

The corrosion characteristics, metallurgical properties, and clinical performance of 38 retrieved internal fixation devices were correlated with the tissue reaction to these devices. Metallurgical parameters included thin and heavy inclusion content, Rockwell hardness, and grain size. The excised fibrous tissue strip was directly overlying each plate at removal and sectioned between screw-hole sites. The material studied from the 38 plates consisted of 201 screw-hole junctions with associated tissue biopsy sites. Clinical histories were obtained on all 38 patients with hardware removal. The average age at the time of plate insertion was 35.6 years (range, 4 to 75 years). Insertion diagnoses included acute trauma (35 patients), joint dislocations (two patients), and fracture nonunion (one patient). The devices included seven upper extremity bone plates, 19 lower extremity bone plates, and 12 hip screw plates. The devices remained in situ an average of 20.4 months (range, 3 to 60 months). Routine asymptomatic removals were performed on 17 of the patients, while the remaining 21 patients were symptomatic at the time of removal. Included in the reasons for symptomatic removal were pain associated with the implant (eight patients), nonunion (four patients), bursae prominence (three patients), and implant breakage (two patients). Significant correlations were found between average tissue reaction scores and average crevice corrosion scores; a trend of increasing average tissue reaction scores with increasing average screw surface corrosion scores also was observed for the 38 devices, although this relationship was not significant. Average crevice corrosion scores and average screw surface corrosion scores were highly correlated for all removals, and for the asymptomatic and symptomatic removal groups. The metallurgical parameters of thin inclusion content and heavy inclusion content also were significantly correlated for all removals, as well as for symptomatic removals. Similarly, significant correlations were found between the individual tissue reaction scores and crevice corrosion scores from the 201 individual sites, again for all devices and for the asymptomatic and symptomatic removal groups. Tissue reaction scores and time in situ showed significant correlation, with tissue reaction decreasing over time. Crevice corrosion and screw surface corrosion scores were not significantly related to time in situ. The results of this study indicate that there is considerable tissue reaction to the corrosion products of this material.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed2000

Tissue responses to molecularly reinforced polylactide-co-glycolide implants.

Plates for internal fixation fabricated from biodegradable polymers degrade via an autocatalytic route. When they are used in bone implants of significant size and thickness, hollowing of the implant may occur while the overall dimensions appear unchanged. We hypothesized that incorporation of a cross-linked polypropylene fumarate matrix into polylactide-co-glycolide bone plates may provide an internal molecular network which prevents implant collapse. Cross-linking reagents of varying hydrophilicity including N-vinylpyrrolidone (VP), hydroxyethylmethacrylate (HEMA), and ethyleneglycol dimethacrylate (EGDMA) were employed. With the objective of determining the most biocompatible and structurally sound composition for molecular reinforcement, we investigated tissue responses in both subcutaneous and orthotopic rodent implantation models in relation to maintenance of implant integrity by histologic, histomorphometric, and stereomicroscopic analysis. Results showed that tissue responses were correlated with dimensional stability of the implants. The most favorable results were seen with the hydrophobic cross-linker EGDMA; this may have been related to the initial reduction of the water uptake by the implant. Cross-linking of polypropylene fumarate with EGDMA within a polylactide-co-glycolide bone plate may offer a means to maintain excellent biocompatibility while improving dimensional stability of biodegradable bone plates.

Animals↗
PubMed1998

Revision arthroplasty of femoral cortex defect using a noncemented stem, Mennen plate, and bone graft.

Twelve patients who underwent total hip replacement complicated by aseptic loosening with severe bone loss were included in this study. Two patients had aseptic loosening of the second revision, six of the third revision, and the remaining four patients of the fourth revision total hip replacement. In all patients, the radiographs revealed an extremely thin cortex around the stem of the prosthesis and almost complete disappearance of one cortex. All patients were treated by revision total hip replacement in conjunction with Mennen plate fixation and allograft bone support. The allograft bone support included three cortical struts and nine massive bone grafts that used cement as a strew. The results were satisfactory in 10 patients in respect to functional activity, pain and radiographic evaluation. In two patients who underwent their fifth revision, the results were unsatisfactory but better than before the operation. Mennen plate fixation provides a sufficient and easy technique for aseptic loosening of total hip replacement with severe bone loss. By preserving the periosteal blood supply, the time required for bone graft incorporation is shortened, resulting in an early final outcome.

Aged↗