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Biomedical subjects

J G Kennedy

Publications and source records attributed to J G Kennedy.

At least 19 recordsLinked to original sources
PubMed2000

Extraskeletal Ewing's sarcoma: a case report and review of the literature.

STUDY DESIGN: Case report. OBJECTIVES: To report on the diagnosis and current treatment of a rare tumor about the cervical spine. SUMMARY OF BACKGROUND DATA: Extraskeletal Ewing's sarcoma (EES) is rare and has not been previously described about the cervical spine. We present a case of a 24-year-old man with a large mass in the posterior triangle of the neck extending through the vertebral foramens of the cervical vertebrae. This was identified as an extraskeletal Ewing's sarcoma. Traditional treatment paradigms have been associated with a poor prognosis. Since the recommendations of the Intergroup Rhabdomyosarcoma Study II study of multimodal chemotherapy and radiotherapy, this tumor has a significantly better prognosis. METHOD: Surgical debulking of the tumor was necessary to relieve cord compression. Histologic analysis was used to confirm both magnetic resonance imaging and computed tomography diagnosis. A chemoradiation therapy program was commenced in accordance with Intergroup Rhabdomyosarcoma Study II recommendations. RESULTS: Computed tomography and magnetic resonance imaging demonstrated a large lobulated mass extending through the exit foramens of C2/C3 and C3/C4. The mass was entirely extraskeletal and extradural. Histologic examination of the excised mass showed microscopy consistent with extraskeletal Ewing's sarcoma. After surgical debulking and chemoradiation, the patient made a complete recovery. CONCLUSION: A review of the literature confirms that extraskeletal Ewing's sarcoma is a rare tumor and particularly so in the region of the cervical spine. Early diagnosis and surgical debulking combined with current multimodality chemoradiation programs can produce a favorable outcome.

Adult↗
PubMed2000

Fatigue failure of an AO spiral blade.

We report an unusual case of a femoral neck stress fracture leading to the fatigue failure of an AO spiral blade. An unreamed femoral nail with a spiral blade was inserted to treat an unstable subtrochanteric femoral fracture. which lead to fracture union at 5 months. Eight months post-operatively the patient started to complain of left hip pain. Serial radiographs revealed progressive osteoporosis of the proximal femur possibly due to the stress sharing effect of a stiff intramedullary device, which continued to bear a significant amount of the transmitted load. The cause of pain was a stress fracture of the femoral neck and the AO spiral blade, which only became radiologically visible 4 months after the start of the symptoms (1 year after the initial operation). The implant was removed and replaced by a cemented hemiarthroplasty. This case reaffirms the difficulty in diagnosing a stress fracture through a metallic implant. The delay in diagnosis may be shortened if stress fracture were included as an expected complication following an intramedullary nailing.

Aged↗
PubMed2000

Evaluation of the role of pin fixation versus collar and cuff immobilisation in supracondylar fractures of the humerus in children.

Long term results of children with supracondylar humeral fractures treated with manipulation and strapping and manipulation followed by pin fixation were evaluated. Forty patients were regarded as Gartland type II injuries. 33 of these were treated with closed reduction and collar and cuff immobilisation and 7 with closed reduction and percutaneous pinning. Two cases of cubitus varus were reported one from each treatment modality. Forty-four patients were included as Gartland type III injuries. Of these 14 were treated with closed reduction and collar and cuff immobilisation, 25 with closed reduction and percutaneous pinning and five with open reduction and pinning. There were two cases of cubitus varus and one case of cubitus valgus following pin fixation. In addition one case of extension lag and one significant ulnar nerve neurapraxia was recorded following pin fixation. One case of cubitus varus was seen following manipulation and collar and cuff treatment. There was no statistical difference between either treatment modality in terms of predicting a better outcome (p0.05). We conclude that pin fixation has no advantages over simple immobilisation in certain Gartland II and III type injuries. Although pin fixation is beneficial in unstable injuries collar and cuff immobilisation continues to have an important role in the treatment of stable supracondylar fractures.

Algorithms↗
PubMed2000

Computerized infrared thermographic imaging and pulpal blood flow: Part 2. Rewarming of healthy human teeth following a controlled cold stimulus.

AIM: To investigate the rewarming pattern and rewarming rate of clinically healthy teeth following a controlled cold stimulus using TI techniques. METHODOLOGY: A controlled cold stimulus was developed using an air stream at 20 degrees C. Gingival and incisal sites on 12 healthy maxillary lateral incisors in six patients were imaged under rubber dam following 20 s cooling. Images were captured at 10 s intervals during a 3-min rewarming period and the data used to construct graphs of the rewarming rate. Log transformation of the data was used to produce 'best fit' straight line graphs. Linear regression analysis was used to examine three variables, viz. the side of the mouth (right or left), the site of measurement (gingival or incisal) and the phase of rewarming (early 0-90 s, late 91-180 s). RESULTS: The mean temperature change (delta t degree C) during rewarming was 8.5 degrees C (SD 1.0 degree C) for gingival sites and 7.2 degrees C (SD 1.1 degrees C) for incisal sites. The slope of the 'best fit' straight line data enabled a rewarming index to be calculated for each site on each tooth. Linear regression analysis showed that the phase of rewarming was highly significant but the other variables were not. A one-way ANOVA showed no significant differences between or within groups. CONCLUSIONS: Three min is an appropriate time to record rewarming of teeth cooled for 20 s with an airstream at 20 degrees C. The side or site used to record surface temperatures using this technique is not significant. Rewarming is exponential and log transformation of the data produces a well-fitting straight line graph. The slope of this line provides a rewarming index which should enable comparison of TI and laser Doppler flowmetry in determining pulpal blood flow as a measure of tooth vitality.

Adult↗
PubMed2000

Computerized infrared thermographic imaging and pulpal blood flow: Part 1. A protocol for thermal imaging of human teeth.

AIM: To observe the thermographic appearance of teeth and to develop a suitable protocol for imaging teeth in human subjects using modern thermographic imaging (TI) equipment in a thermologically controlled environment. METHODOLOGY: The emissivity of enamel was investigated using an extracted incisor tooth. A total of 12 unrestored maxillary lateral incisors in six healthy patients were then imaged under rubber dam after a 20-min equilibration period and the thermographic data analysed using a dedicated software package. Recordings were made from standardized gingival and incisal sites on each tooth and the temperature gradient established for each tooth. Subsequently, a sequence of images of both maxillary central incisors in one patient was stored every 30 s during a 20-min equilibration period with and without an air-conditioning unit in operation. RESULTS: For the lateral incisors there was a consistent temperature gradient (mean 1.28 degrees C) from gingival area to incisal area and there were no statistically significant differences between right and left sides for the gingival site (t = 0.34, NS) or the incisal site (t = 0.62, NS). The air-conditioning unit had a rapid and profound cooling effect. With the air-conditioning disabled there was a mean tooth surface temperature increase of 1.1 degrees C from 0 to 5 min of the equilibration period and 0.3 degree C from 15 to 20 min. CONCLUSIONS: There was no significant difference in gingival or incisal temperatures between pairs of contralateral maxillary lateral incisors and a consistent temperature gradient existed from gingival to incisal areas of healthy maxillary lateral incisor teeth. The protocol described is suitable for TI of vital teeth. However, TI measured tooth surface temperature only which was extremely sensitive to air currents. A 15-min acclimatization period under rubber dam was adequate to allow stable tooth surface temperature measurement.

Adolescent↗
PubMed2000

Deep vein thrombosis prophylaxis in hip fractures: a comparison of the arteriovenous impulse system and aspirin.

BACKGROUND: A prospective, randomized controlled trial was used to compare the efficacy of the arteriovenous (AV) impulse system and aspirin in reducing venous thrombosis after fracture to the femoral neck. METHODS: A total of 143 patients underwent hemiarthroplasty, after which 70 patients were treated with the AV pump and a second group of 73 patients were commenced on 325 mg of aspirin. Duplex ultrasound was used to assess both proximal and distal venous thrombi on days 7 to 10. Calf and thigh circumferences were also measured. RESULTS: Thrombi developed in seven of the patients treated with aspirin and in four patients treated with the AV pump. No statistically significant difference could be established (p = 0.109). There was a significant reduction in both calf (p = 0.003) and thigh (p = 0.002) swelling in the group treated with the AV pump. Neither treatment group was a significant predictor of a poorer outcome by using logistical regression analysis (p = 0.258). CONCLUSIONS: Both aspirin and the AV pump are effective in reducing thromboembolic events after hemiarthroplasty of the hip.

Aged↗
PubMed2000

Massive subperiosteal hemorrhage and femoral shaft osteonecrosis: a complication of tissue plasminogen activator therapy for purpura fulminans.

We present the case of a child who developed a massive subperiosteal hemorrhage and subsequent osteonecrosis of her right femur after treatment with tissue plasminogen activator for post-varicella streptococcal purpura fulminans. Radiographs showed posteromedial translation of the capital femoral epiphysis on the necrotic shaft, and the hip was immobilized. The femur slowly remodeled and has continued to grow. The child is independently ambulatory with a 2.1-cm leg length discrepancy, a varus deformity of the hip, and a valgus distal femur.

Bone Remodeling↗
PubMed2000

An investigation into the role of oxygen free radical scavengers in preventing polymethylmethacrylate-induced necrosis in an osteoblast cell culture.

This study examined the effect of polymethylmethacrylate (PMMA) on osteocytic necrosis and the role of free radical scavengers in minimizing this damage. Bovine osteoblast cells with a characteristic phenotype were seeded at a density of 4x10(4) cells/cm2 and cultured in a DMEM supplemented with 10% fetal calf serum. A transwell insert with 2 cc of PMMA was suspended above the culture, and a time log response curve was established following elusion of free radicals around the osteoblast media. Chemiluminescence was used to determine quantitative free radical release. Using a Student's two-tailed t test there was a significant difference in the amount of hydroxyl radical released at 1-6 hours compared with controls (P=.028). Using histologic markers, there was a significant correlation between the use of PMMA and osteoblast cell necrosis. Transwell plates were coated with varying concentrations of mannitol, a known hydroxyl radical scavenger. A log dose response curve was established. There was a clear statistical association between a 10% mannitol solution and a reduction in the free radical release from PMMA (P=.03). Similarly, using Trypan blue histologic staining, there was a significant reduction in PMMA-induced cell necrosis when 10% mannitol was used as a scavenger (P=.01). A Rockwell superficial hardness test was used to determine whether mannitol had any effect on the surface hardness of the polymer. No statistical difference could be found between those treated with mannitol and controls at a depth of up to 1 mm. These results demonstrate hydroxyl radical is released from the polymerization reaction of PMMA. These radicals cause cell death in an osteoblast culture medium. This has been addressed using a 10% mannitol solution, which reduced cell necrosis.

Cells, Cultured↗
PubMed1999

Predictors of outcome in cauda equina syndrome.

This retrospective review examined the cause, level of pathology, onset of symptoms, time taken to treatment, and outcome of 19 patients with cauda equina syndrome (CES). The minimum time to follow up was 22 months. Logistical regression analysis was used to determine how these factors influenced the eventual outcome. Out of 19 patients, 14 had satisfactory recovery at 2 years post-decompression; 5 patients were left with some residual dysfunction. The mean time to decompression in the group with a satisfactory outcome was 14 h (range 6-24 h) whilst that of the group with the poor outcome was 30 h (range 20-72 h). There was a clear correlation between delayed decompression and a poor outcome (P = 0.023). Saddle hypoaesthesia was evident in all patients. In addition complete perineal anaesthesia was evident in 7/19 patients, 5 of whom developed a poor outcome. Bladder dysfunction was observed in 19/19 patients, with 12/19 regarded as having significant impairment. Of the five patients identified as having a poor overall outcome, all five presented with a significant sphincter disturbance and 4/5 were left with residual sphincter dysfunction. There was a clear correlation between the presence of complete perineal anaesthesia and significant sphincter dysfunction as both univariate and multivariate predictors of a poor overall outcome. The association between a slower onset of CES and a more favourable outcome did not reach statistical significance (P = 0.052). No correlation could be found between initial motor function loss, bilateral sciatica, level or cause of injury as predictors of a poor outcome (P>0.05). CES can be diagnosed early by judicious physical examination, with particular attention to perineal sensation and a history of urinary dysfunction. The most important factors identified in this series as predictors of a favourable outcome in CES were early diagnosis and early decompression.

Adult↗
PubMed1999

A comparison of four extraction methods for substance P, neurokinin A and calcitonin gene-related peptide from human dental pulp tissue.

Measuring neuropeptides in biological tissues by radioimmunoassay requires efficient extraction that maintains their immunoreactivity. Many different methods for extraction have been described, but there is little information on optimal extraction methods for individual neuropeptides from human dental pulp tissue. The aim was therefore to identify an effective extraction procedure for three pulpal neuropeptides; substance P, neurokinin A and calcitonin gene-related peptide. Tissue was obtained from 20 pulps taken from teeth freshly extracted for orthodontic reasons. The pulp samples were divided into four equal groups and different extraction methods were used for each group. Boiling whole pulp in acetic acid gave the highest overall yield and, in addition, offered an easy and rapid means of pulp tissue processing. The use of protease inhibitors did not increase the recovery of the immunoreactive neuropeptides but did provide the best combination of maximal recoveries and minimal variability. These results should be useful for planning the extraction of these neuropeptides from human pulp tissue in future studies.

Acetic Acid↗
PubMed1998

An evaluation of the Weber classification of ankle fractures.

This retrospective study over a 3 year follow-up was designed to establish the significance of the Weber classification of ankle fractures with regards to functional and radiographic outcome. One hundred and seven patients were available for follow-up, of which 88 ankles could be classified with the Weber system. Medial malleolar fractures alone and pilon fractures could not be classified with this system. A correlation was found between the type of Weber fracture and the overall ankle score. This held true for unimalleolar fractures alone. More complex bimalleolar and trimalleolar fractures did not follow this convention. Logistical regression analysis was used to evaluate other predictors of outcome. Bimalleolar and trimalleolar fractures were statistically significant predictors of a poorer outcome (P = 0.033, P = 0.021). The initial degree of displacement was also determined to be a predictor of outcome (P = 0.0133) as was the operative reduction (P = 0.0113). Using linear regression, older age (> 62 years) was also established as a predictor of a poorer outcome (P < 0.05). The Weber classification was found to be a predictor of outcome in unimalleloar ankle fractures and not for multimalleolar fractures. We have identified further predictors of a poorer outcome in ankle fractures as the degree of initial injury, the number of malleoli fractured and older age. These factors were found to have greater significance in predicting outcome than the level of fibular fracture alone. We have identified a deficiency of the Weber system in excluding these criteria and have addressed this by modifying the existing system to include the number of malleoli involved, thus providing a more useful prognostic tool.

Adolescent↗
PubMed1998

Bond strength of repaired anterior composite resins: an in vitro study.

The objectives of this study were to investigate the repair potential of two commercially available composite resins in terms of bond strength, and the effectiveness of two commercially available adhesive systems used as intermediary materials in the repaired specimens. The repair strength of Helio Progress (HP) and Herculite XRV (XRV) was tested using two bonding agents: DenTASTIC (DT) and All Bond 2 (AB2). The effect of surface abrasion of specimens and the effect of time on repair strength were also investigated. Surface abrasion significantly improved the bond strength (P < 0.001) and the use of bonding agents further enhanced bond strength but not significantly. Use of bonding agents alone improved the repair bond strength significantly (P < 0.001). Repair of HP with HP after surface abrasion and application of DT produced the highest repair bond strength which was 99% of the cohesive strength of the control (unrepaired) specimens. Although there were some differences in the bond strength over the time period of the study (one month) none of these was statistically significant. It is concluded that surface abrasion coupled with the application of bonding agent produces the highest repair strength. It seems likely that clinically acceptable bond strengths are possible after repair of anterior composite resins.

Composite Resins↗
PubMed1998

Effect of acetabular component orientation on recurrent dislocation, pelvic osteolysis, polyethylene wear, and component migration.

We retrospectively reviewed 75 total hip arthroplasties to examine the effect of acetabular component position. In group A, 38 of the components were implanted according to manufacture's instructions with all peripheral fins in contact with acetabular bone; as such, the acetabular components were in a relatively vertical position with a mean angle of inclination of 61.9 degrees. Three of these patients developed recurrent dislocations necessitating revision of the acetabular component. In group B, 37 hips, a more horizontal orientation was used despite the fact that all of the peripheral fins of the acetabular component did not engage acetabular bone; in this group the mean angle of inclination was 49.7 degrees. Only one of these hips recurrently dislocated and required revision. There were no problems in this group associated with provisional component stability caused by inadequate peripheral fixation. Radiographs of all patients were obtained at 4 years after surgery (range, 4.0-4.3 years). Pelvic osteolysis had occurred in 24% of hips in group A and 13% of group B. Asymmetric polyethylene wear was observed in 5.1% of the hips in group A; no hip in group B showed wear asymmetry. Acetabular component migration developed in 19% of group A hips and 5% of group B hips. The Mayo clinical hip score was excellent in both groups: group A 71/80, group B 73/80. At an intermediate follow-up it is clear that significant problems can be encountered when this component is positioned in a relatively vertical position to facilitate engaging all four peripheral fins in bone. We have addressed this problem by placing the cup in a more anatomic position of inclination while maintaining provisional rim fixation. This has resulted in a decreased incidence of pelvic osteolysis and fewer complications overall.

Aged↗
PubMed1997

Population-based study of risk of venous thromboembolism associated with various oral contraceptives.

BACKGROUND: Four studies published since December, 1995, reported that the incidence of venous thromboembolism (VTE) was higher in women who used oral contraceptives (OCs) containing the third-generation progestagens gestodene or desogestrel than in users of OCs containing second-generation progestagens. However, confounding and bias in the design of these studies may have affected the findings. The aim of our study was to re-examine the association between risk of VTE and OC use with a different study design and analysis to avoid some of the bias and confounding of the earlier studies. METHODS: We used computer records of patients from 143 general practices in the UK. The study was based on the medical records of about 540,000 women born between 1941 and 1981. All women who had a recorded diagnosis of deep-vein thrombosis, venous thrombosis not otherwise specified, or pulmonary embolus during the study period, and who had been treated with an anticoagulant were identified as potential cases of VTE. We did a cohort analysis to estimate and compare incidence of VTE in users of the main OC preparations, and a nested case-control study to calculate the odds ratios of VTE associated with use of different types of OC, after adjustment for potential confounding factors. In the case-control study, we matched cases to controls by exact year of birth, practice, and current use of OCs. We used a multiple logistic regression model that included body-mass index, number of cycles, change in type of OC prescribed within 3 months of the event, previous pregnancy, and concurrent disease. FINDINGS: 85 women met the inclusion criteria for VTE, two of whom were users of progestagen-only OCs. Of the 83 cases of VTE associated with use of combined OCs, 43 were recorded as deep-vein thrombosis, 35 as pulmonary thrombosis, and five as venous thrombosis not otherwise specified. The crude rate of VTE per 10,000 woman-years was 4.10 in current users of any OC, 3.10 in users of second-generation OCs, and 4.96 in users of third-generation preparations. After adjustment for age, the rate ratio of VTE in users of third-generation relative to second-generation OCs was 1.68 (95% CI 1.04-2.75). Logistic regression showed no significant difference in the risk of VTE between users of third-generation and second-generation OCs. Among users of third-generation progestagens, the risk of VTE was higher in users of desogestrel with 20 g ethinyloestradiol than in users of gestodene or desogestrel with 30 g ethinyloestradiol. With all second-generation OCs as the reference, the odds ratios for VTE were 3.49 (1.21-10.12) for desogestrel plus 20 g ethinyloestradiol and 1.18 (0.66-2.17) for the other third-generation progestagens. INTERPRETATION: The previously reported increase in odds ratio associated with third-generation OCs when compared with second-generation products is likely to have been the result of residual confounding by age. The increased odds ratio associated with products containing 20 micrograms ethinyloestradiol and desogestrel compared with the 30 micrograms product is biologically implausible, and is likely to be the result of preferential prescribing and, thus, confounding.

Adolescent↗
PubMed1997

Parturition-induced pelvic dislocation: a report of four cases.

OBJECTIVE: To describe our experience with four cases of severe pelvic dislocation associated with difficult parturition. DESIGN: Retrospective case series. PATIENTS: Four patients, each with rupture of the symphysis pubis and sacroiliac joints during labor. All injuries were associated with significant initial pain and disability. All developed persistent symptoms related to the sacroiliac disruption. INTERVENTIONS: The three patients who had presented acutely were freated with closed reduction and application of a pelvic binder. Two underwent closed reduction of their pelvic dislocation while anesthetized with a general anesthetic. One patient (N.A.), who presented late, had not been treated with a binder. RESULTS: All four patients had persistent posterior pelvic (sacroiliac) pain. In two patients a postpartum neuropathy persisted. CONCLUSIONS: Severe pelvic dislocations are rare during labor, with conservative treatment reported to be successful in most cases. The persistence of symptoms in our patients emphasizes the need for careful examination and follow-up of these rare injuries. Because the outcome in our patients was poor and results in the literature are equivocal, we suggest the consideration of an operative approach to treatment in patients with symphyseal diastasis of > 4.0 cm.

Adult↗