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Biomedical subjects

Paul J Dougherty

Publications and source records attributed to Paul J Dougherty.

10 recordsLinked to original sources
PubMed2006

Bilateral comparison of conventional versus topographic-guided customized ablation for myopic LASIK with the NIDEK EC-5000.

PURPOSE: To compare visual acuity and higher order aberrations before and after myopic LASIK using conventional versus customized ablation. METHODS: This prospective, randomized study included 54 myopic eyes in 27 patients who underwent bilateral LASIK using the NIDEK EC-5000 excimer laser system (NIDEK Technologies, Gamagori, Japan). Customized aspheric treatment zone (CATz) treatment was used in one eye (CATz group) and conventional ablation (conventional group) was used in the fellow eye. Uncorrected visual acuity (UCVA) and higher order aberrations (root-mean-square [RMS] in 4-mm and 6-mm zones) of both groups were observed with the NIDEK OPD-Scan aberrometer before and 3 months after LASIK. Preoperative mean refractive error was similar for both eyes of each patient (P>.05). RESULTS: No statistically significant differences were noted in preoperative higher order aberrations (RMS in 4-mm and 6-mm zones) between groups (P>.05). No statistically significant difference was noted between pre- and postoperative higher order aberrations in the CATz group (P>.05). However, a highly statistically significant increase in higher order aberrations was observed after conventional ablation (P<.001). There was a statistically significant higher increase of higher order aberrations after LASIK in the conventional group than the CATz group (P<.05). Postoperative UCVA with both conventional and customized ablation was not significantly different (P>.05). CONCLUSIONS: LASIK with conventional ablation and CATz ablation resulted in the same UCVA. The increase in higher order aberrations after CATz ablation was less than after conventional ablation.

Adolescent↗
PubMed2006

Preoperative characteristics of patients undergoing LASIK in 1997 versus 2004 at one surgical eye center in China.

PURPOSE: To compare the preoperative characteristics of LASIK patients undergoing surgery in 1997 versus 2004 at one of the principal eye surgical centers in China. METHODS: Preoperative data of patients who underwent LASIK in 1997 and 2004 were recorded and retrospectively compared. RESULTS: In 1997, the mean spherical equivalent refraction of the 824 eyes of 428 patients undergoing LASIK surgery was -7.30 +/- 4.65 diopters (D), with a mean patient age of 24.67 +/- 6.76 years. Students represented 45.05% of patients undergoing surgery in 1997. In 2004, the mean spherical equivalent refraction of the 8434 eyes of 4286 patients undergoing LASIK surgery was -6.66 +/- 3.31 D, with a mean patient age of 25.20 +/- 6.59 years. Students represented >50% of patients undergoing surgery in 2004. There were significant differences in the constitution ratio of occupation and the spherical equivalent refractions between 1997 and 2004 (t=-2.712, chi-squared=25.117, respectively, P<.05). CONCLUSIONS: At our center in China, the majority of LASIK patients are young and have myopia ranging from -3.00 to -10.00 D. Students were much more likely than any other occupation to undergo LASIK. The number of patients undergoing LASIK at our center in China has increased exponentially from 1997 to 2004, with an average annual increase in surgical volume of approximately 40%.

Academic Medical Centers↗
PubMed2006

Conversion from temporary external fixation to definitive fixation: shaft fractures.

Temporary external fixation is the most common method of initial stabilization of diaphyseal fractures in forward surgical hospitals. Once the patient arrives at a stable environment, usually the United States, the fracture is managed with intramedullary nailing, small-pin external fixation, or a modified external fixator. Future research should be directed toward improving methods of care. It is not precisely known when is the best time to convert to definitive fixation without increasing the risk of infection. The risk factors leading to infection and nonunion are not well-established, making that determination even more difficult. Clinical studies of a suitable size should provide insight into these problems. Although temporary external fixation is commonly used, an optimal construct has not been determined. Data from studies of in vivo fracture-site motion after application of the temporary external fixator should be compared with biomechanical testing of similar constructs. These data could be used to recommend optimal temporary external fixation constructs of tibia, femur, and humerus fractures using currently available devices as well as to provide groundwork for the next generation of fixators.

External Fixators↗
PubMed2003

A comparison of two military temporary femoral external fixators.

Temporary external fixation of femur fractures, used at civilian trauma centers for patients who cannot tolerate more extensive procedures, also is planned for use in military field hospitals to provide temporary stabilization and allow for safe transport of a patient to the next level of care. The purpose of the current study was to evaluate three constructs: an external fixator made by one manufacturer and two Hoffman II constructs: uniplanar and biplanar. The study consisted of two parts: a biomechanical study of each of the three constructs and the application of each of the two Hoffmann II constructs to separate cadaver thighs by resident surgeons. Five resident surgeons participated in the study using five pairs of cadaver thighs. The biplanar construct was stiffer in axial and torsional stability when compared with the uniplanar construct. There was no difference in the amount of time needed to apply the constructs nor was either construct found to be subjectively easier to apply by the surgeons. There was an increased number of unicortical pins and plunges (when a pin inadvertently slips over the side) with the uniplanar construct when compared with the biplanar. The biplanar construct is biomechanically more stable and appears to allow for more accurate placement of pins.

Biomechanical Phenomena↗
PubMed2003

Long-term follow-up of unilateral transfemoral amputees from the Vietnam war.

BACKGROUND: Despite their frequency, few reports exist concerning the initial and long-term consequences of battle-incurred unilateral transfemoral amputations. METHODS: A retrospective cohort design was used to measure the long-term health of transfemoral battle amputees treated at a single hospital during the Vietnam War. Data collection consisted of medical record abstraction and a follow-up questionnaire that included the SF-36 Health Survey. RESULTS: Forty-six patients responded to the survey an average of 28 years after injury. Compared with the controls, patient responses to the SF-36 were significantly (p < 0.01) less in all categories except Mental Health and Vitality. Forty-three (93.5%) are or have been married. Forty-one (89.1%) are or have been employed an average of 20.1 years. Forty patients (87%) wore a prosthesis an average of 13.5 h/day. CONCLUSION: Although the patients do relatively well with employment and marriage stability, the low SF-36 scores suggest a significant disability.

Amputees↗
PubMed2003

Endogenous cortisol production in response to knee arthroscopy and total knee arthroplasty.

BACKGROUND: There is controversy about whether patients who take exogenous glucocorticoids, such as prednisone, require supplemental (exogenous) glucocorticoids in order to meet the physiological demands of surgery. In this study, we sought to define the magnitude of the surgical stress response in normal patients undergoing major and minor elective orthopaedic surgery. METHODS: A prospective, observational study of thirty patients who had not taken exogenous glucocorticoids and who underwent either elective knee arthroscopy or elective unilateral total knee arthroplasty was performed. Regional anesthesia was used for all patients, and all patients treated with total knee arthroplasty had continuous epidural anesthesia for forty-eight hours after the surgery. The stress response was assessed on the basis of serum and twenty-four-hour urine cortisol levels; comparisons of the urine values were made after correcting for renal function by calculating the cortisol-to-creatinine clearance ratio. RESULTS: Preoperatively, patients undergoing arthroscopy and total knee arthroplasty had similar cortisol-to-creatinine clearance ratios. Patients treated with total knee arthroplasty had a significant (p < 0.001) surgical stress response on the day of the surgery, compared with baseline, whereas patients treated with arthroscopy did not. The mean cortisol-to-creatinine clearance ratio in patients treated with total knee arthroplasty was highest on the day of the surgery and decreased on the third postoperative day. However, on the third postoperative day, the cortisol-to-creatinine clearance ratio still was significantly higher than the baseline value (p < 0.001). Significant differences in the serum cortisol levels also were detected between the patients treated with arthroscopy and those treated with total knee replacement. CONCLUSIONS: Patients undergoing total knee arthroplasty had a significant surgical stress response (a seventeenfold increase in the cortisol-to-creatinine clearance ratio); patients treated with arthroscopy did not. Additional studies, including a prospective trial of patients taking exogenous glucocorticoids, are warranted. Until they are performed, the significantly increased cortisol production observed in non-steroid-dependent patients following total knee arthroplasty leaves open the possibility that steroid-dependent patients undergoing this procedure could benefit from perioperative glucocorticoid supplementation. Since the non-steroid-dependent patients in the present series did not mount a substantial stress response to knee arthroscopy, our results do not support the use of supplemental steroids for that less-invasive procedure.

Arthroplasty, Replacement, Knee↗
PubMedDate not supplied

Analysis of fixation methods for vertical shear fractures of the medial malleolus.

OBJECTIVE: To evaluate 4 different fixation methods used to treat vertical shear fractures of the medial malleolus. METHODS: Eighty polyurethane models of the distal tibia were osteotomized in a reproducible manner to create a vertical shear fracture of the medial malleolus. Twenty specimens were then randomly assigned to 1 of 4 fixation groups. Two fixation groups used a neutralization plate, whereas 2 groups were screw-only constructs. Ten of the specimens in each group were then randomly assigned to undergo either offset axial or offset transverse loading. RESULTS: The construct using a neutralization plate with 2 screws in the distal fragment exhibited greater stiffness in offset axial loading compared with the screw-only constructs placed an equivalent distance from the tibial plafond. All specimens in the group with the properly applied neutralization plate exhibited elastic deformation, whereas the majority of the specimens in all other groups showed residual displacement or catastrophic failure of the construct. CONCLUSION: Fixation of vertical shear fractures of the medial malleolus with a properly applied neutralization plate offers a significant mechanical advantage over screw-only constructs.

Ankle Injuries↗
PubMedDate not supplied

The thin-flap LASIK technique.

PURPOSE: To determine if LASIK using a 130-microm microkeratome head (thin-flap LASIK) is as visually effective and safe as when using a 160-microm head. METHODS: A study was performed comparing postoperative day 1 uncorrected visual acuity (UCVA) and flap complications in eyes undergoing myopic LASIK with a 130-microm head versus a 160-microm head using the BD K-3000 microkeratome (BD Ophthalmic Systems, Waltham, Mass). RESULTS: The mean preoperative myopia in the 155 eyes of 80 patients in the 130-microm head group was -5.00+/-2.53 diopters (D) compared to -3.78+/-1.73 D in the 279 eyes of 148 patients in the 160-microm head group. The groups were otherwise similar in terms of age, preoperative cylinder, and best spectacle-corrected visual acuity. The geometric mean postoperative day 1 UCVA was 20/25 in the 130-microm head group compared to 20/26 in the 160-microm head group. The only flap complication in the series was a single partial flap in the 160-microm head group. CONCLUSIONS: LASIK with a 130-microm head (thin-flap LASIK) is as visually effective and safe as when using a 160-microm head with the BD K-3000 microkeratome.

Adult↗
PubMedDate not supplied

Incidence of complications during flap creation in LASIK using the NIDEK MK-2000 microkeratome in 26,600 cases.

PURPOSE: To evaluate the incidence of intraoperative complications using the NIDEK MK-2000 microkeratome during flap creation in LASIK. METHODS: The incidence of intraoperative flap complications during LASIK using the NIDEK MK-2000 microkeratome was retrospectively studied in 26,600 procedures performed in 5 outpatient excimer laser surgery centers. RESULTS: A total of 65 (0.244%) complications were identified: 23 (0.086%) eyes had free caps, 13 (0.049%) eyes had an incomplete pass, 13 (0.049%) eyes had an epithelial defect, 11 (0.041%) eyes had buttonhole, and 5 (0.019%) eyes had irregular flap. The remaining 26,535 (99.756%) eyes had uneventful flap creation. CONCLUSIONS: Use of the NIDEK MK-2000 microkeratome resulted in a low incidence of intraoperative complications, making it a safe and reliable device for creating flaps during LASIK.

Corneal Stroma↗