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Biomedical subjects

K G Shea

Publications and source records attributed to K G Shea.

18 recordsLinked to original sources
PubMed2000

Defining the pediatric spinal thoracoscopy learning curve: sixty-five consecutive cases.

STUDY DESIGN: Consecutive case prospective chart and radiographic review. OBJECTIVES: The purpose of this study was to define the learning curve of spinal thoracoscopy. SUMMARY OF BACKGROUND DATA: Thoracoscopy is an alternative to open thoracotomy in the treatment of pediatric spinal deformity. The learning curve for spinal thoracoscopy has not been described. METHODS: In this prospective study 65 consecutive cases of thoracoscopic anterior release with discectomy and fusion performed by one surgeon for the treatment of pediatric spinal deformity were reviewed. The patients were, on average, 14 +/- 3 years old and had the following diagnoses: idiopathic scoliosis (n = 13), Scheuermann's kyphosis (n = 9), neuromuscular spinal deformity (n = 35), congenital scoliosis (n = 4), and tumor/syrinx (n = 4). RESULTS: The average operative time for the thoracoscopic procedure was 161 +/- 41 minutes (range, 50-240 minutes). There was a slight decrease in the average operative time as the series progressed. The average number of discs excised was 6.5 +/- 1.5 (range, 3-10), and the number increased as the series progressed. The average operative time per disc was 29.3 +/- 7.7 minutes in the first 30 patients compared with 22.3 +/- 4.7 minutes in the next 35 patients (P < 0.01). The average blood loss during the thoracoscopic procedure was 301 +/- 322 mL (range, 25-2000 mL) and did not decrease as the series progressed. Initial postoperative scoliosis and kyphosis corrections were 59% +/- 17% and 92% +/- 12%, respectively. Complications occurred in six patients (cases 4, 8, 17, 31, 39, and 46) and were evenly distributed throughout the series. CONCLUSIONS: The learning curve for thoracoscopy is substantial, but not prohibitive. This technique provides a safe and effective alternative to thoracotomy in the treatment of pediatric spinal deformity.

Adolescent↗
PubMed1998

A comparison of manual versus computer-assisted radiographic measurement. Intraobserver measurement variability for Cobb angles.

STUDY DESIGN: A comparison between computer-assisted measurement using digitized radiographs, which has the potential to reduce error, and manual measurement using standard radiographs. OBJECTIVE: To assess measurement variability for the Cobb method on digital radiographs and compare it with that of manual measurements on standard radiographs. BACKGROUND DATA: Studies of the Cobb method have demonstrated multiple sources of error leading to significant intraobserver measurement variability. Estimates for the 95% confidence interval for intraobserver variability range from 2.8 degrees to 10 degrees. METHODS: Twenty-four scoliosis radiographs were measured by six examiners. Two measurement sets were done manually ("manual set"), and two measurement sets were done on digitized images using a computer mouse ("computer set"). RESULTS: For the manual set, the 95% confidence interval for intraobserver variability was 3.3 degrees (range, 2.5-4.5 degrees). For the computer set, the value was 2.6 degrees (range, 2.3-3.3 degrees). This difference in 95% confidence intervals between the manual and computer sets was statistically significant (P < 0.001). CONCLUSIONS: The results of this study demonstrate that intraobserver variability for manual and computer Cobb angle measurements yield a 95% confidence interval of approximately 3 degrees, with the computer having a slightly lower variability. The computer technique removes sources of intrinsic error, e.g., the variability introduced by using different manual protractors, the inaccuracy of standard protractors, and the use of wide-diameter radiographic markers. Identical digital images can be shared electronically between centers, without having to duplicate and mail films. Multicenter studies in which different examiners will be measuring Cobb angles may consider using the computer as a measuring device to reduce intrinsic measurement errors.

Arthrography↗
PubMed1998

Technique for identification of submicron metal particulate from implants in histological specimens.

Metal implants are being used with increasing frequency for the treatment of many diseases in the field of orthopedics, cardiology, cardiovascular surgery, and otolaryngology. Unfortunately, metals can be a source of submicron particles, which may have adverse effects on tissues. This article describes a technique that uses backscattered electron imaging and energy dispersive X-ray microanalysis, which have the capacity to perform both quantitative and qualitative analysis. The particles can be characterized by size, shape, amount, and composition. Although this technique can be used near the implant interface, it is particularly helpful in tissues a great distance from the implant site with a low concentration of metal debris. In addition, the sensitivity and specificity of this technique can be adjusted to the investigator's needs.

Electron Probe Microanalysis↗
PubMed1997

Analysis of particles in acetabular components from patients with osteolysis.

Acetabular polyethylene components were quantitatively analyzed for the presence of third body particles from 38 consecutively retrieved components. Backscattered electron imaging and correlated energy dispersive x-ray analysis were used for the assessments. Retrievals were divided into 4 groups based on methods of fixation and metal alloy types: 8 hydroxyapatite coated, 6 cobalt chrome porous coated, 17 titanium porous coated, and 7 cemented implants were evaluated. The backscattered electron imaging data showed that the components from the hydroxyapatite coated implants had larger particles than did the components from the cemented group. The hydroxyapatite group had 51 +/- 52 particles per mm2. The cobalt chrome alloy group had 10 +/- 9 particles per mm2, and the titanium alloy group had 9 +/- 16 particles per mm2. The cemented group had 5 +/- 4 particles per mm2. The difference between the cement group and the hydroxyapatite group was statistically significant. The elemental analysis showed that 70% of the particles in the hydroxyapatite group had calcium and phosphorus elements. Third body particles likely contribute to particulate generation. The results suggest that the hydroxyapatite coated components have the potential for producing greater amounts of particulate debris. Continued analysis of retrieved components for the presence of the third body particles is required.

Acetabulum↗
PubMed1997

Lymphoreticular dissemination of metal particles after primary joint replacements.

Twenty-three patients with a history of primary joint replacement followed by lymph node dissection procedure were studied. These specimens included pelvic, gastric, paraaortic, inguinal, retroduodenal, and axillary node chains. The lymph node specimens were sectioned, processed for scanning electron microscopic study, and viewed with backscattered electron imaging to identify metal particles. On detection of a metal particle, energy dispersive x-ray microanalysis was conducted to determine its elemental composition. Seven of 23 patients had metal alloy particles within the lymph node specimens. Metal particles were identified in the pelvic and axillary node chains. In each case, the metal alloy identified corresponded with the implanted type of alloy. The shortest interval between joint implantation and dissemination of metal to a lymph node chain was 6 months. These data suggest the need for continued followup to determine long term effects, if any, of this distribution of metal particles through the lymphatic system.

Aged↗
PubMed1997

Pemberton pericapsular osteotomy to treat a dysplastic hip in cerebral palsy.

We reviewed the results of Pemberton pericapsular osteotomy in nineteen hips (fifteen patients) that were subluxated (fifteen hips) or dislocated (two hips) or had severe acetabular dysplasia (two hips) secondary to spastic cerebral palsy. At least one concomitant procedure was performed in fifteen hips. These procedures included an intertrochanteric osteotomy to correct excessive femoral anteversion or valgus deformity of the neck-shaft angle (thirteen hips), a soft-tissue release (nine hips), and an open reduction (three hips). Four hips had no concomitant procedure. Five of the nineteen hips were painful preoperatively. The average age of the patients at the time of the index operation was seven years and nine months (range, three years and five months to twelve years and three months). The average duration of follow-up was ten years and nine months (range, three years and one month to nineteen years and nine months). All osteotomy sites healed without complications. At the latest follow-up examination, all of the hips were pain-free and satisfactorily reduced and none of the patients had deterioration in function. The average center-edge angle was -5 degrees (range, -45 to 18 degrees) preoperatively and 38 degrees (range, 17 to 53 degrees) at the latest follow-up examination. The average migration index of Reimers was 55 per cent (range, 30 to 100 per cent) preoperatively compared with 12 per cent (range, 0 to 46 per cent) at the latest follow-up examination. Sixteen of the nineteen hips were followed until closure of the triradiate cartilage. There were no instances of posterior uncovering or osteonecrosis of the femoral head or premature closure of the triradiate physeal cartilage leading to deficient acetabular coverage. Our results suggest that good clinical and radiographic results can be achieved with the Pemberton pericapsular osteotomy, with simultaneous intertrochanteric osteotomy and soft-tissue release when indicated, as treatment for subluxation or dislocation of the hip or acetabular dysplasia in cerebral palsy.

Cerebral Palsy↗
PubMed1997

Fixation methods in contaminated wounds and massive crush injuries of the forearm.

This article presents a critical review of the current literature on the stabilization methods of severe open fractures or crush injuries of the forearm. Due to the complexity of the problem, the advantages and disadvantages of the different fixation methods are presented in order to provide the reader with a combination of possibilities for timing and decision-making when confronted with such fractures in clinical practice.

Bone Transplantation↗
PubMed1996

Inability of energy dispersive X-ray analysis to identify particulate polyethylene.

There are limitations to all techniques used to identify particulate polyethylene in histological specimens. The goal of our study was to determine if remnant metal elements used during the catalytic production of ultra high molecular weight polyethylene, could be used as markers for particulate polyethylene detection in histological specimens. It was hypothesized that these catalyst elements could be detected in polyethylene using energy dispersive X-ray elemental analysis. Six samples from five different companies were evaluated. These included virgin polymer powder, polyethylene bar stock, and artificial joint components. Five specimens from each of the six samples were analyzed with energy dispersive X-ray elemental analysis. After elemental analysis was completed, only 2 of 30 specimens were positive for the catalyst elements. In the remaining 28 specimens, catalyst elements were not detected. Our investigation demonstrates that energy dispersive X-ray elemental analysis is not currently a feasible method of particulate polyethylene detection. Additional techniques will need to be developed to accurately identify particulate polyethylene in histological specimens.

Beryllium↗
PubMed1996

Analysis of lymph nodes for polyethylene particles in patients who have had a primary joint replacement.

Polarized light microscopy has been used for more than forty years to identify polyethylene particles in histological specimens; however, few investigators have assessed the specificity of this technique. We examined specimens from dissected lymph nodes for the presence of strongly birefringent particles resembling polyethylene. Twenty-seven patients had dissection of lymph nodes after a total joint replacement (Group 1), and a control group of eighteen patients had dissection of lymph nodes before a total joint replacement (Group 2). Specimens from both groups of lymph nodes were examined under plain and polarized light. The presence of strongly birefringent particulate debris was graded from 0 to 4. Twenty-one (78 per cent) of the twenty-seven patients in Group 1 and eight of the eighteen patients in Group 2 had strongly birefringent particles in the lymph nodes. Our results demonstrate that, in the assessment of the systemic dissemination of polyethylene in the lymphoreticular system, polarized light microscopy has important limitations. More refined techniques employing polarized light and other methods of physical and chemical analysis may be necessary to identify polyethylene particles accurately within the lymphoreticular system and periprosthetic tissue.

Adult↗
PubMed1992

Manual demands and consequences of rock climbing.

Types of rock climbing, hand-grip techniques, and training practices used by rock climbers are described. A survey was completed by 46 climbers. Three fourths of the climbers reported a climbing-related injury; of these injured climbers, almost one half reported a hand or wrist injury. More than half of the injured climbers had been treated by a physician for their injury. More than half of all climbers reported distal interphalangeal or proximal interphalangeal joint pain while climbing. Case reports of three climbers with acute hand injuries are presented to illustrate the minimal effects of their residual deficits on their climbing abilities. A wider understanding of the manual aspects of rock climbing and an awareness of the patterns and incidence of injuries in this sport will facilitate prevention, treatment, and rehabilitation.

Adolescent↗
PubMed1990

Project Alpha. Designing courses that recruit and retain OR nurses.

Those who participated in developing and teaching the courses gained many new skills including writing objectives and test questions, public speaking, and expertise in the topics they taught. Another benefit was the sense of pride and accomplishment in developing and presenting a quality postgraduate program. This was reinforced by student evaluations as the course progressed. In addition, they were paid by the college as salaried faculty members. The clinical preceptors benefited through the relationships they developed with their students. They were given the opportunity to exhibit their clinical skills and experienced pride and satisfaction as their novice colleagues grew. The students reaped the benefit of instruction from perioperative nurses who were enthusiastic and committed to the practice of perioperative nursing. They also received information from experienced nurses who were functioning in the OR on a daily basis. The small class size was another benefit because it allowed ample time for questions and individual instruction. Project Alpha has been an ongoing focus of the AORN of Alameda County for approximately 10 years. The chapter began with a three-day observational experience for sophomore nursing students and moved on to include a perioperative elective and management preceptorship for upper-division nursing students. Most recently, the chapter has supported the postgraduate perioperative course described in this article. The nurses completing this postgraduate program enter perioperative practice with a strong base of knowledge and sense of professionalism.

California↗
PubMedDate not supplied

Preossified longitudinal epiphyseal bracket of the foot: treatment by partial bracket excision before ossification.

The longitudinal epiphyseal bracket is a rare ossification defect of tubular bones in the hand and foot. This deformity contains an abnormal secondary ossification center, which may lead to progressive shortening and angular deformity of involved bones. This article describes the results from early treatment of this deformity before the secondary ossification center ossifies. Four patients with seven involved bones (5 metatarsals and 2 phalanges) were treated with surgical excision of the longitudinal epiphyseal brackets, without corrective osteotomy. The average age at surgery was 16 months (range, 6-20 months), and the average follow-up period was 55 months (range, 31-80 months). All five metatarsal patients demonstrated progressive improvement in the deformity. Of the two phalanx patients, one improved and the other did not. Early treatment of the longitudinal epiphyseal bracket before ossification of the secondary center with excision is effective in correcting this deformity. Long-term follow-up assessment until skeletal maturity is necessary to assess the final results of surgery because corrective osteotomy may be necessary for patients who do not have adequate correction.

Bone Diseases, Developmental↗
PubMedDate not supplied

Microvascularized free fibular grafts for reconstruction of skeletal defects after tumor resection.

A microvascularized free fibular graft was used to reconstruct a skeletal defect after tumor reconstruction in 13 consecutive patients. The patients were evaluated at an average follow-up of 53 months (range, 30-71). The status of each graft was evaluated for time to union, hypertrophy, functional evaluation, and complications. The average time to union was 6.5 months, and significant graft hypertrophy occurred in eight of 13 patients. Complications occurred in seven patients. Two of the 13 patients required removal of the microvascularized graft. Functional evaluation according the the Musculoskeletal Tumor Society yielded an average score of 90 (range, 83-97). The results were rated good or excellent in 11 of 13 patients, and two were rated failures. The microvascularized fibular graft provides an attractive option for the reconstruction of skeletal defects after tumor resection. The results of this procedure are especially good in skeletally immature patients.

Adolescent↗
PubMedDate not supplied

Posttraumatic cavovarus deformity of the foot.

The peroneus longus has long been known as a plantar flexor of the first ray, which, with muscle imbalance as seen in neurovascular disease, can lead to cavovarus of the foot. This article describes a traumatic laceration of the peroneus brevis that went on to cause cavovarus presumably by its inactivity as an everter of the foot. This substantiates the need for primary repair of this major tendon as well as raises interesting biomechanical issues in foot mechanics.

Atrophy↗