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Biomedical subjects

R C Edwards

Publications and source records attributed to R C Edwards.

At least 19 recordsLinked to original sources
PubMed2001

The fate of resorbable poly-L-lactic/polyglycolic acid (LactoSorb) bone fixation devices in orthognathic surgery.

PURPOSE: The aim of this study was to evaluate the long-term outcome of resorbable poly-L-lactic/polyglycolic acid (PLLA-PGA) bone fixation devices used for fixation of maxillary and mandibular osteotomies. MATERIALS AND METHODS: Twelve patients were postoperatively evaluated. Eight patients who had undergone bilateral sagittal split mandibular osteotomies that had been fixed with PLLA-PGA screws were followed-up for up to 2 years postoperatively with radiographs. One of these patients underwent a bone biopsy for detailed histologic evaluation of the screw fixation sites. Two patients who had undergone mandibular symphyseal osteotomies were also radiographically evaluated at 18 months to 2 years postoperatively. Two patients who had Le Fort I osteotomies fixed with PLLA-PGA plates and screws underwent open exploration of the operated sites for visual examination. RESULTS: All 8 mandibular osteotomy patients showed radiographic screw hole lucency immediately after surgery that remained unchanged in the first year after surgery. By 18 months postoperatively, all 48 screw holes showed near or complete trabecular bone fill. The bone biopsy of one screw hole at 2 years postoperatively showed complete fill with normal trabecular bone. No residual polymer material or fibrous scar was seen. The mandibular symphyseal sites showed complete elimination of all screw holes by 2 years postoperatively, with only faint evidence of intraosseous tunnels. The maxillary sites showed complete bone healing along the osteotomies and no evidence of residual fixation material or bone defects in the screw holes. No communication with the maxillary sinus was seen in the fixation sites. CONCLUSION: This orthognathic patient series showed complete resorption of the PLLA-PGA fixation devices without osteolysis in maxillary and mandibular bone sites by 18 to 24 months after surgery.

Absorbable Implants↗
PubMed2001

Fixation of bimaxillary osteotomies with resorbable plates and screws: experience in 20 consecutive cases.

PURPOSE: This study evaluated the potential effectiveness of resorbable plate and screw fixation for skeletal stabilization of simultaneously performed maxillary and mandibular osteotomies. PATIENTS AND METHODS: Twenty consecutive patients underwent simultaneous maxillary and mandibular osteotomies that were fixed using copolymeric poly L-lactic acid/polyglycolic acid (PLLA/PGA) plates and screws. Prefabricated acrylic intermediate and final splints were used as guides and then removed at completion of the surgery. Guidance elastics were applied at 2 weeks postoperatively. RESULTS: The LeFort I osteotomies included segmentalizations with and without bone grafts (7/20), impactions (4/20), advancements (8/20), and unilateral downgrafting with a bone graft (2/20)- one of which was segmental. The mandibular sagittal split osteotomies involved advancements (11/20), setbacks (5/20), and asymmetric rotation (4/20). Three patients had simultaneous genioplasties, which were also stabilized with resorbable fixation. All maxillae were fixed with four 2.0-mm L-shaped plates and screws. The mandibular rami were maintained with three 2.5-mm bicortical screws per side. The mandibular symphyseal segments were held in position with two or three 2.5 mm bicortical screws. All surgeries were accomplished uneventfully, and no problems in the immediate postoperative stability of the occlusion were encountered. Follow-up ranged from 12 to 25 months. CONCLUSIONS: The initial clinical findings suggest that this form of bone fixation is a viable alternative to standard metallic fixation techniques for certain maxillomandibular deformities in which excessive bony movements are not performed. Differences exist in both intraoperative application and postoperative management of masticatory function. This is partially a US government work. There are no restrictions on its use.

Absorbable Implants↗
PubMed2000

Resorbable fixation techniques for genioplasty.

PURPOSE: This study evaluated the capability and effectiveness of resorbable bone fixation devices in genioplasty surgery. MATERIALS AND METHODS: Twenty patients underwent different genial movements that were stabilized with either 2.5-mm polylactic-polyglycolic acid lag screws or 2.0-mm polylactic-polyglycolic acid plates and screws. RESULTS: Twenty-one anterior mandibular osteotomies were performed in 20 patients. Sixteen patients had advancement (80%), 2 had horizontal setback (10%), and 2 had vertical reduction (10%). The average advancement was 7.6 mm (range, 4 to 14 mm), the average horizontal setback was 6.0 mm (range, 4 to 8 mm), and the average vertical reduction was 7.0 mm (range, 5 to 9 mm). Fixation was done using the lag screw technique in 13 patients (65%) and plate and screw fixation in 7 patients. (35%) Intraoperative stability was satisfactory in all cases. There were no postoperative infections or segmental instability up to 6 months after surgery. CONCLUSION: Resorbable polylactic-polyglycolic acid lag screw and plate and screw fixation is a viable alternative for fixation of anterior horizontal osteotomies of the mandible.

Absorbable Implants↗
PubMed1999

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

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

Absorbable Implants↗
PubMed1998

Resorbable fixation of Le Fort I osteotomies.

We review our experience with resorbable fixation in Le Fort I osteotomies. We used resorbable plates and screws for fixation of 29 Le Fort I osteotomies over a 1-year period (October 1996-November 1997). Patients ages ranged from 13 to 38 years (mean, 24.7 years). The postoperative follow-up ranged from 2 weeks to 1 year. At the time of surgery, the fixation devices were evaluated for stability and satisfactory placement of fixation. Postoperatively, they were evaluated for wound healing, fixation stability, signs of infection, and patient satisfaction. Postoperative evaluations consisted of 1-, 3-, and 6-week clinical exams with radiographic analysis at 3, 6, and 12 months. There have been no complications as of this writing. In one instance, an L plate was palpable in the paranasal region and resolved after 6 months. Our early experience with resorbable fixation is favorable and has offered us an additional option for stabilization of the maxilla.

Absorption↗
PubMed1995

Parathyroid hormone-related protein (PTHrP) in breast cancer and benign breast tissue.

Parathyroid hormone-related protein (PTHrP) 1-86 was quantified by immunoassay in extracts of 132 breast cancers, 27 samples of normal breast tissue and four fibroadenomas. PTHrP 1-86, was detected in 68% of primary tumours (range 40-302,000 fmol/g), 33% of normal breast tissues (range 100-1800 fmol/g), and all four fibroadenomas (range 110-11,600 fmol/g). PTHrP displayed molecular heterogeneity on gel filtration chromatography, and 1-86, 1-34 and 37-67 immunoreactivity eluted as 25-27 kDa together with a peak of 19-21 kDA containing only 37-67 activity. Tumour PTHrP 1-86 levels correlated inversely with age (P < 0.05) and were higher in premenopausal women (P = 0.05). The proportion of tumours containing PTHrP was higher in axillary node positive premenopausal women (P < 0.05). These data suggest that oestrogen may regulate expression of PTHrP in breast cancer and that production of PTHrP may be linked to development of axillary node metastases.

Adult↗
PubMed1994

Patient-controlled analgesia: a comparison of dosing regimens for acute postsurgical pain.

This study compares several dosing regimens for patient-controlled analgesia (PCA) in the management of acute maxillofacial surgical pain. The dosing methods differed by presence or absence of an active drug (morphine [MS] vs saline), presence of a baseline infusion, and dose of drug delivered. Sixty-eight patients were enrolled in this prospective, randomized, double-blind, placebo-controlled trial that lasted 24 hours. The study was completed in two separate parts, each of which involved randomization of patients into four groups (part I) or three groups (part II). No significant differences were noted in pain scores in the preoperative, immediate postoperative, or 4-, 8-, 12-, or 24-hour periods among any of the groups, including the saline-only control groups; in either part I or part II of the study. Significant differences (P < .01), however, were noted in nausea and vomiting scores. Fifty percent (50%) of patients receiving MS vomited, while no patients in the saline groups vomited. This study calls into question the usefulness of PCA with MS in maxillofacial surgery patients. Pain control was questionable at best, and the rate of emesis was unacceptably high in patients with potentially compromised airways. Further research is required to determine if other analgesics provide better pain control with less nausea in the PCA system or if antiemetics can effectively be used to lower the incidence of nausea and vomiting.

Adolescent↗
PubMed1993

Expanding the specialty: a survey of oral and maxillofacial surgery residencies in the United States.

This article reports the results of a survey of oral and maxillofacial surgery (OMS) residency program directors regarding teaching of expanded scope surgical procedures during the academic year 1990 to 1991. Data is provided for the nation as a whole, as well as grouped by geographic regions and type of residency program. Significant differences were found for some procedures based on both geographic region and program type. The majority of program directors responding to this survey disagreed with the trend toward expanding the scope of OMS into cosmetic procedures. Directors of integrated dual degree programs believed that the trend toward expanding the scope of OMS was positive; 2:1 over directors of MD optional or traditional OMS programs.

Curriculum↗
PubMed1992

Autogenous conchal cartilage as a replacement after a diskectomy.

A surgical procedure to place autogenous conchal cartilage as an interpositional graft after a diskectomy is described. The apparent advantages of this procedure are as follows: (1) the form of the external ear corresponds to joint morphology; (2) a graft of adequate size can be harvested; (3) the form of the external ear remains unchanged after surgery; (4) the graft can be obtained adjacent to the surgical site; (5) biologically acceptable material is used; (6) the additional expense of allogeneic grafts is avoided; and (7) excellent results have been reported.

Cartilage, Articular↗