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PubMed2006

Success rate of catheter ablation in atrial flutter: comparison of a 4- or 5-mm tip electrode catheter with an 8-mm tip electrode catheter.

BACKGROUND: Radio frequency (RF) energy is capable of interrupting the reentrant circuit of atrial flutter and curing the arrhythmia. The development of 8-mm tip catheter provides more tissue damage and has offered the promise of improved success. The purpose of our study was to determine if the acute and long-term success with the 8-mm tips were superior to the 4- or 5-mm tips. MATERIALS AND METHODS: The outcomes of the first 20 patients in whom an 8-mm tip catheter was used were compared with the previous 20 patients in whom a 4-or 5-mm tip catheter was used. Procedural (acute) ablation success was defined by creation of bi-directional isthmus block. Long-term success was defined as the prevention of clinically evident atrial flutter (AFl) as determined by the absence of symptoms or maintenance of sinus rhythm on electrocardiogram, six months to one year after the procedure. RESULTS: Compared to the 4- or 5-mm tip, the 8-mm catheter tip was associated with a reduced ablation duration {22.3 +/- 16 versus 11.5 +/- 5 min (p = 0.0078)}, a lower mean number of ablations {13.5 +/- 9.9 versus 6.8 +/- 2.9 (p = 0.0065)} and a reduced procedure time {1.8 +/- 0.7 versus 1.1 +/- 0.5 h (p = 0.0032)}. Acute success was 95% in the 4- or 5-mm group versus 80% in the 8-mm group (p = NS), but long-term success was higher in the 8-mm group than the 4- or 5-mm group (87.5 versus 63.2%, p = 0.0436). CONCLUSIONS: Eight-millimeter tip catheters for AFl shorten procedure time, reduce the duration and number of ablations and accomplish bi-directional block when compared with smaller tipped catheters. The long-term success rate is better with the 8-mm tips and should be the preferred catheter for RF ablation of AFl.

Aged↗

PubMedDate not supplied

Arthrodesis of the equine proximal interphalangeal joint: a biomechanical comparison of three 4.5-mm and two 5.5-mm cortical screws.

OBJECTIVE: To compare the biomechanical characteristics and mode of failure of 2 parallel-screw techniques for proximal interphalangeal joint arthrodesis in horses. STUDY DESIGN: Randomized block design, blocking for horse (1-5), method of screw fixation (three 4.5-mm vs two 5.5-mm), side (left limb vs right limb), and end (front limb vs hind limb). Constructs were loaded to failure in 3-point bending in a dorsal-to-palmar (plantar) direction. SAMPLE POPULATION: Twenty limbs (10 limb pairs) from 5 equine cadavers. METHODS: A combined aiming device was used to facilitate consistent screw placement. Three parallel 4.5-mm cortical screws were placed in lag fashion in 1 limb of a pair, and 2 parallel 5.5-mm cortical screws were placed in lag fashion in the contralateral limb. Arthrodesis constructs were tested in 3-point bending in a dorsal-to-palmar (plantar) direction using a materials-testing machine. Loading rate was 19 mm/s. Maximal bending moment at failure and composite stiffness were obtained from bending moment-angular deformation curves. Data were analyzed using ANOVA and chi(2) analysis. RESULTS: There were no significant differences in bending moment (P >.05, power = 0.8 @ delta = 19%) or composite stiffness (P >.05, power = 0.8 @ delta = 19%) between the 2 fixation techniques. Higher maximal bending moment was found in front limbs than hind limbs, and front limbs with two 5.5-mm screws than hind limbs with two 5.5-mm screws. In all cases, constructs completely failed. A greater number of 4.5-mm cortical screws failed than 5.5-mm cortical screws. CONCLUSIONS-In pastern arthrodesis constructs loaded in 3-point bending, end (front limb vs hind limb) affected maximal bending moment at failure of constructs. There was no significant effect of horse, treatment, or side on maximal bending moment or stiffness. Two 5.5-mm cortical screws should provide a surgically simpler pastern arthrodesis than three 4.5-mm cortical screws while maintaining similar biomechanical characteristics. CLINICAL RELEVANCE: Three 4.5-mm screws or two 5.5-mm screws will provide similar biomechanical characteristics in bending when performing equine pastern arthrodesis.

Animals↗

PubMed1996

Transjugular intrahepatic portosystemic shunt procedure: efficacy of 10-mm versus 12-mm Wallstents.

PURPOSE: To compare results of transjugular intrahepatic portosystemic shunt (TIPS) placement with 10- and 12-mm Wallstents. MATERIALS AND METHODS: Forty-six TIPS procedures in 47 patients were retrospectively reviewed. Wallstents that were 10 mm in diameter were used in 23 patients, and those that were 12 mm in diameter were used in 23 patients. Immediate results were compared, which included initial portosystemic gradient and Doppler measurements of blood flow velocity through the shunt at 1 day. Long-term patency and velocities were also assessed. RESULTS: TIPS were successfully created in 46 of 47 patients (98%). In one patient in the 10-mm group, the portal vein could not be accessed. When compared with TIPS in the 10-mm group, TIPS placed in the 12-mm group required dilation to larger diameters (mean, 11.1 vs 9.2 mm; P < .0001) to achieve an identical target gradient of 10 mm Hg and exhibited lower 1-day velocities (mean, 1.3 m/sec vs 1.7 m/sec; P < .03). The 1-day occlusion rate was 17% (four of 23 patients) in the 12-mm group versus 0% in the 10-mm group (P < .02). Patient survival was statistically significantly less in the 12-mm group (P < .03). CONCLUSION: Twelve-millimeter Wallstents yield statistically significantly poorer short- and long-term results in TIPS procedures. This is most likely due to the decreased radial strength of the larger stent, which is 50% less than that of the 10-mm stent.

Adolescent↗

PubMed1999

Transient electric birefringence of human erythroid spectrin dimers and tetramers at ionic strengths of 4 mM and 53 mM.

In conventional electrooptic studies the sample ionic strength must for technical reasons be kept below about 3 mM, which is only 2% of the ionic strength at physiological conditions. In particular for flexible polyelectrolytic macromolecules it can in general not be ruled out that both the conformational average and dynamics at ionic strength 3 mM and below may differ significantly from what it is at physiological conditions. Here we report on the first electrooptic study of human erythroid spectrin dimers and tetramers at ionic strengths higher than 3 mM. All measurements in this study were carried out at both ionic strength 4 mM (2.5 mM HEPES + 1 mM NaCl) and 53 mM (2.5 mM HEPES + 50 mM NaCl). Spectrin tetramers were studied only at 4 degrees C whereas the dimers were studied at both 4 degrees C and 37 degrees C. At 4 degrees C there is a striking quantitative similarity between the transient electric bire-fringence (TEB) of spectrin dimers and tetramers. Also, the TEB of spectrin dimers at 37 degrees C was very similar to the results at 4 degrees C. The contour length and the molecular weight of spectrin dimers and tetramers are known. The dominating TEB relaxation time is in all cases only a fraction of what is predicted theoretically if the spectrin dimers and tetramers are assumed to be stiff and extended molecules. In sum, the new TEB data constitute strong electrooptic evidence confirming that spectrin dimers and tetramers have a highly flexible structure, and demonstrate for the first time that a major part of the intrachain dynamics of the spectrin is quite insensitive to an increase of the ionic strength from 4 mM to 53 mM. Use of the reversing electric field pulse technique for all conditions studied yields TEB data suggesting that the orientation of both spectrin dimers and tetramers in an electric field is dominated by a permanent rather than an induced electric dipole moment.

Biophysical Phenomena↗

PubMed1999

Performance comparison of the Alcon Legacy 20000 1.1 mm TurboSonics and 0.9 mm MicroTip.

PURPOSE: To compare the efficiencies of the operative procedures, the changes in postoperative corneal endothelial cell density (ECD), and incision performance after cataract surgery using 2 different phacoemulsification tips. SETTING: Wolfe Clinic, Marshalltown, Iowa, USA. METHODS: A randomized prospective study of 119 consecutive cases was conducted. All patients were adults having phacoemulsification using a modified in situ fracture technique. All cases were done by 1 surgeon using the Alcon Legacy 20000 phacoemulsification machine with normal vacuum cassettes and tubing. One of 2 45 degree phacoemulsification tips was used: the 1.1 mm TurboSonics (n = 65) or the 0.9 mm MicroTip (n = 54). Measurements at the time of surgery included metered phacoemulsification time and mean phacoemulsification power. Corneal keratometry and ECD by contact specular microscopy were determined preoperatively and 10 weeks postoperatively. RESULTS: The mean metered phacoemulsification time was statistically significantly different between the 2 groups: 1.1 mm TurboSonics = 1.25 minutes; 0.9 mm MicroTip = 1.66 minutes. The mean ultrasound power was also significantly different: 1.1 mm TurboSonics = 52.98%; 0.9 MicroTip = 49.07%. Loss of corneal ECD was not significantly different: 1.1 mm TurboSonic = 3.68%; 0.9 mm MicroTip = 5.79%. Mean diopters of induced incisional keratometric flattering was similar: 1.1 mm TurboSonics, 0.32 diopters (D) +/- 0.61 (SD); 0.9 mm MicroTip, 0.25 +/- 0.49 D. There were no cases of anterior radial capsule tear, posterior capsule tear, vitreous loss, iris aspiration, suture closure, or incision leak. CONCLUSIONS: Although a longer mean metered phacoemulsification time was required with the 0.9 mm MicroTip, corneal endothelial cell loss and incisional keratometric performance were not different from those of cases in which the larger 1.1 mm TurboSonics tip was used. Both tips can be used effectively and safely for phacoemulsification of the human cataract.

Cataract Extraction↗

PubMedDate not supplied

CT evaluation of mediastinal lymphadenopathy: noncontrast 5 mm vs postcontrast 10 mm sections.

OBJECTIVE: Two CT techniques were compared in the assessment of mediastinal lymph nodes: 5 mm thick sections without intravenous contrast medium and 10 mm thick sections with intravenous contrast medium. MATERIALS AND METHODS: Seventy-nine adult patients were examined by chest CT. From the level of the aortic arch through the level of the right middle lobe bronchus 5 mm thick sections were performed without intravenous contrast medium, followed by 10 mm thick sections of the same region with intravenous contrast medium. Two chest radiologists separately reviewed each CT method for each patient. Mediastinal lymph nodes were localized according to the American Thoracic Society scheme. Lymph node diameter was measured on the short axis. RESULTS: The 5 mm thick noncontrast sections permitted identification of more mediastinal lymph nodes than the 10 mm thick contrast enhanced sections (p < 0.01, signed rank test). The 5 mm thick unenhanced sections tended to show slightly (1-2 mm) larger nodes than the 10 mm thick contrast enhanced sections (stations 7, 10R, both reviewers, p < 0.05, signed rank test). Nodes with a short axis diameter > or = 8 mm were identified comparably well using either CT technique. CONCLUSION: The present study indicates that CT of the mediastinum using 5 mm thick sections, without intravenous contrast medium, is an appropriate scanning technique for evaluation of mediastinal lymphadenopathy.

Adult↗

PubMedDate not supplied

Arthrodesis of the equine proximal interphalangeal joint: a biomechanical comparison of two 7-hole 3.5-mm broad and two 5-hole 4.5-mm narrow dynamic compression plates.

OBJECTIVE: To compare the biomechanical characteristics and mode of failure of two different dynamic compression plate (DCP) techniques for proximal interphalangeal joint (PIPJ) arthrodesis in horses. STUDY DESIGN: Randomized block-design blocking on horse (1-5), method of fixation (two 7-hole, 3.5-mm broad DCP vs two 5-hole, 4.5-mm narrow DCP), side (left, right), and end (front, hind). Constructs were loaded to failure in 3-point bending in a dorsal-to-palmar (plantar) direction. SAMPLE POPULATION: Ten paired limbs from 5 equine cadavers. METHODS: Two 7-hole, 3.5-mm broad dynamic compression plates (bDCP) were used in 1 limb of a pair, and two 5-hole 4.5-mm narrow dynamic compression plates (nDCP) were used on the contralateral limb. Plates were positioned abaxially across the dorsomedial and dorsolateral aspect of the PIPJ. Arthrodesis constructs were loaded (19 mm/s) in 3-point bending in a dorsal-to-palmar (plantar) direction using a materials-testing machine. Composite stiffness, yield point, and maximal bending moment at failure were obtained from bending moment-angular deformation curves. Data were analyzed using ANOVA, X(2) analysis, and Fisher's exact tests; the power of the test was calculated when differences were not significant. RESULTS: There were no significant differences in composite stiffness (P >.05; power = 0.8 @ delta = 21.9%), yield point (P >.05; power = 0.8 @ delta = 34.4%), or maximal bending moment (P >.05; power = 0.8 @ delta = 17.8%) between the two fixation techniques. For bDCP constructs, 11% (15 of 140) of the 3.5-mm screws were damaged; 7 of the screw heads pulled through plates where the plates bent, 1 screw head broke off, and 7 screws were bent or pulled out of the phalanx. For nDCP constructs, 8% (8 of 100) of the 4.5-mm screws were damaged; 1 screw head pulled through a plate, 1 screw head broke off, and 6 screws were bent or pulled out of the phalanx. CONCLUSIONS: There were no biomechanical or failure differences between bDCP and nDCP fixation of the PIPJ in horses when evaluated in single-cycle 3-point bending to failure. CLINICAL RELEVANCE: There is no biomechanical advantage to the use of two 7-hole, 3.5-mm bDCP in equine proximal interphalangeal arthrodesis compared with two 5-hole, 4.5-mm nDCP. Two 5-hole, 4.5-mm nDCP may be easier to place, whereas two 7-hole, 3.5-mm bDCP may provide more versatility in fracture repair.

Animals↗

PubMed1985

Effects of pedal frequency on VO2 and work output at lactate threshold (LT), fixed blood lactate concentrations of 2 mM and 4 mM, and max in competitive cyclists.

To determine the effects of differing pedal frequencies on VO2 and work output values at the lactate threshold (LT), fixed blood lactate concentrations of 2 mM and 4 mM (2 mM, 4 mM), and at max, nine male competitive road racing cyclists (USCF category I or II) completed three VO2 max tests; on a Monark bicycle ergometer, at pedal frequencies of 60, 90, and 120 rpm. Each stage was 3 min in duration, starting at 0 kgm/min with subsequent stages increased by either 180 kgm/min (60 and 120 rpm) or 178 kgm/min (90 rpm). Blood samples were taken during the last 30 s of each stage. VO2 and work output at LT, 2 mM, and 4 mM were determined from individual blood lactate-work rate and VO2-work rate relationships. VO2 max and maximal work output were chosen as the peak values observed during the VO2 max tests. Results indicated that work output at LT, 2 mM, and 4 mM was affected by choice of pedal frequency (1278, 1140, 999 kgm/min at LT; 1533, 1450, 1182 kgm/min at 2 mM; 1780, 1703, 1487 kgm/min at 4 mM; for 60, 90, and 120 rpm, respectively, P less than 0.05). Max work output at 60 and 90 rpm was significantly greater (P less than 0.05) than at 120 rpm (2035, 2053, 1879 kgm/min for 60, 90, and 120 rpm, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Post-dural puncture headache in young orthopaedic in-patients: comparison of a 0.33 mm (29-gauge) Quincke-type with a 0.7 mm (22-gauge) Whitacre spinal needle in 200 patients.

The incidence of postdural puncture headache (PDPH) following spinal anaesthesia with a 0.33 mm (29-gauge) and two types of 0.7 mm (22-gauge) Whitacre needles was investigated in 400 patients less than 40 years old. The incidence of PDPH was 2% in the 0.33 mm group, and 3.5% in the 0.7 mm group. Headache of other origin was seen in 12 patients (6%) in the 0.33 mm and in five patients (2.5%) in the 0.7 mm group. These differences were not significant. The failure rate was significantly higher in the 0.33 mm group (8.5% vs 2%) than in the 0.7 mm group (P less than 0.05). It is concluded that the 0.33 mm needle is associated with a low incidence of PDPH in young patients, but has a significantly higher failure rate than the Whitacre 0.7 mm needle, which is also a suitable choice in this age-group because of its ease of handling and the low incidence of PDPH.

Adolescent↗

PubMed2004

Microfoam ultrasound-guided sclerotherapy treatment for varicose veins in a subgroup with diameters at the junction of 10 mm or greater compared with a subgroup of less than 10 mm.

OBJECTIVE: The objective was to analyze the effectiveness of foam ultrasound-guided sclerotherapy treatment in saphenous veins and tributary veins with a diameter at the saphenofemoral or saphenopopliteal junction of > or =10 mm and compare these results with a subgroup of veins with diameters of < 10 mm. METHODS: A subgroup of 17 saphenous veins with a diameter at the saphenofemoral or saphenopopliteal junction of > or =10 mm were compared with a subgroup of 98 saphenous veins with a diameter of < 10 mm at the saphenofemoral or saphenopopliteal junction for clinical efficacy and patient satisfaction at a mean 2-year follow-up. RESULTS: A mean number of 2.15 treatments utilizing an average of 8.37 mL of foam sclerosing solution (3% sodium tetradecyl sulfate) were required to close all incompetent varicose veins in the < 10-mm group versus a mean of 2.8 treatments and 13.9 mL foam (3% sodium tetradecyl sulfate) for the > or =10-mm group. A total of 27.5% of saphenous veins of < 10 mm and 37.5% of saphenous veins > or = 10 mm required a second treatment at 3 months. One-hundred percent of patients believed that their legs were successfully treated at 2-year follow-up in both groups with 94% of the < 10-mm group noting improvements in quality of life and 100% in the > or =10-mm group. CONCLUSIONS: Ultrasound-guided foam sclerotherapy is effective in treating all sizes of varicose veins with high patient satisfaction and improvement in quality of life. Duplex ultrasound findings demonstrated a small increase in failure to close the saphenofemoral or saphenopopliteal junction with increasing size of junction diameter, but this does not significantly alter the results with respect to clearance of visible varicosities and patient satisfaction with results.

Adult↗

PubMedDate not supplied

Arthrodesis of the equine proximal interphalangeal joint: a mechanical comparison of 2 parallel 5.5 mm cortical screws and 3 parallel 5.5 mm cortical screws.

OBJECTIVE: To compare the biomechanical characteristics and mode of failure of 2 techniques using parallel 5.5 mm screws for pastern joint arthrodesis in horses. STUDY DESIGN: Randomized block design, for horse (1-5), method of fixation (two 5.5 mm screws versus three 5.5 mm screws), side (right, left), and end (front, hind). Constructs were tested to failure in 3-point bending. SAMPLE POPULATION: Twenty limbs (5 cadavers). METHODS: A combined aiming device was used to facilitate screw placement. Two parallel 5.5 mm screws were inserted in lag fashion in 1 limb of a pair, and three 5.5 mm screws were inserted in the contralateral limb. Constructs were then tested in 3-point bending in a dorsal-to-palmar (plantar) direction using a materials testing machine at a loading rate of 19 mm/s. Maximal bending moment at failure and stiffness were obtained from bending moment-angular deformation curves. RESULTS: There was no significant difference between two and three 5.5 mm screw constructs for bending moment and stiffness (P<.05). All constructs ultimately failed by bone fracture or screw bending. For proximal interphalangeal (PIP) joint arthrodesis constructs loaded in 3-point bending, no significant effect of treatment, side, or end on maximal bending moment or stiffness was detected. CONCLUSIONS: Two 5.5 mm cortical screws inserted in parallel should provide a surgically simpler and equally strong PIP joint arthrodesis compared with three 5.5 mm cortical screws. CLINICAL RELEVANCE: Two 5.5 mm cortical screws inserted in parallel for PIP joint arthrodesis should perform similarly under conditions used in this study, as three 5.5 mm screws inserted in a similar manner, when loaded under bending.

Animals↗

PubMedDate not supplied

Comparison of 5-mm and 6-mm ablation zones in photorefractive keratectomy for myopia.

BACKGROUND: Variation in ablation zone diameter may alter visual acuity and/or refractive effect in photorefractive keratectomy. Despite theoretical benefits of using a smaller diameter ablation zone, clinical studies suggest that a larger ablation zone may decrease problems associated with photorefractive keratectomy. METHODS: The results of our initial 34 consecutive eyes treated with a 5-mm diameter ablation zone using a Summit Technology ExciMed UV200LA excimer laser were compared retrospectively to our initial 34 consecutive eyes treated with a 6-mm diameter ablation zone using a Summit OmniMed excimer laser. Eyes had a spherical equivalent refraction between -1.00 and -6.00 diopters (D) and astigmatism less than 1.00 D. Patients were followed for a minimum of 6 months. RESULTS: Eyes treated with a 6-mm ablation zone had less hyperopia and a spherical equivalent refraction closer to emmetropia at 1, 2, and 3 months (P = 0.001). Eyes treated with a 6-mm ablation zone had better uncorrected visual acuity at 1 and 2 months (P = 0.001). Less subepithelial haze was noted at 2 months (P = 0.01) and 3 months (P = 0.002) in the 6-mm group. At 6 months postoperatively, 30 of 32 eyes (94%) treated with a 6-mm ablation zone had a spherical equivalent refraction within 0.50 D of emmetropia, and all 32 eyes (100%) were within 1.00 D of emmetropia; in the 5-mm ablation zone group, 28 of 34 eyes (80%) were within 0.50 D and 29 (85%) were within 1.00 D of emmetropia. Patients treated with a 6-mm ablation zone complained less of night halos and had fewer differences between night and day vision. CONCLUSIONS: In this study of myopia of -1.00 D to -6.00 D, eyes treated with a 6-mm ablation zone achieve a more rapid visual recovery with less variation in refractive outcome and less adverse effects than those treated with a 5-mm ablation zone.

Adult↗

PubMed1998

Prospective randomized comparison of phacoemulsification cataract surgery with a 3.2-mm vs a 5.5-mm sutureless incision.

PURPOSE: To report sutureless cataract surgery by phacoemulsification with a 3.2-mm surgical incision compared with a 5.5-mm surgical incision. METHOD: In a prospective, randomized, masked clinical trial of phacoemulsification cataract surgery, 55 eyes (55 patients) had a 3.2-mm incision and 56 eyes (56 patients) had a 5.5-mm incision. All incisions were in the superior vertical meridian, commenced 1.5 mm posterior to the limbus, and extended into the cornea for a total length of 2.5 to 3.0 mm. In a masked fashion, astigmatism was monitored by keratometry, and logMAR visual acuity was determined both with and without best correction throughout a mean follow-up of 33.9 months. RESULTS: Statistically significant differences were seen in favor of the 3.2-mm incision group at the final examination for astigmatism (Cravy analysis) and uncorrected visual acuity (-0.18 vs -0.88 diopter, P < .001; logMAR, 0.14 vs 0.26, P = .04). CONCLUSIONS: Over the long term, phacoemulsification with a 3.2-mm incision is associated with significantly less astigmatic shift and better uncorrected visual acuity than is phacoemulsification with a 5.5-mm incision. A small incision with a foldable intraocular lens has long-term benefits.

Aged↗

PubMed1999

Performance comparison of the Alcon Legacy 20000 1.1 mm TurboSonics and 0.9 mm Aspiration Bypass System tips.

PURPOSE: To compare the efficiencies of the operative procedures and the reductions in postoperative corneal endothelial cell density (ECD) after cataract surgery using 2 different phacoemulsification tips and their associated cassettes and tubing. SETTING: Wolfe Clinic, Marshalltown, Iowa, USA. METHODS: A randomized prospective study of 100 consecutive cases was conducted. All patients were adults having phacoemulsification using a hybrid in situ fracture technique. All cases were performed by 1 surgeon using the Alcon Legacy 20000 phacoemulsification machine. One of 2 45 degree phacoemulsification tips and associated cassettes and tubing were used: the 1.1 mm TurboSonics with normal tubing (n = 47) or the 0.9 mm Aspiration Bypass System (ABS) tip with high-vacuum cassettes and tubing (n = 53). Measurements at the time of surgery included metered phacoemulsification time, percentage power used, total time spent in the phacoemulsification process, and milliliters of balanced salt solution (BSS) used. Corneal ECD was determined preoperatively and 10 weeks postoperatively. An independent statistician performed 2-sample t tests or Wilcoxon rank sum tests on the data. RESULTS: There were no cases of anterior radial capsule tear, posterior capsule tear, vitreous loss, iris aspiration, incision leak, or suture closure. There was no correlation between amount of corneal ECD loss and any operative variable measured. Similar measurements for the 1.1 mm TurboSonics and the 0.9 mm ABS included, respectively, ECD loss 7.34% and 8.22%; metered phacoemulsification time 1.29 and 1.22 minutes; total time of the phacoemulsification process 113 and 105 seconds. There were statistically significant differences between the 1.1 mm TurboSonics tip and 0.9 mm ABS tip performance in mean power percentage overall (52% versus 48%) and overall BSS volume used (85 versus 76 mL). CONCLUSIONS: The 0.9 mm ABS phacoemulsification tip used with the high-vacuum cassette and tubing provided the physical advantages of tip-size reduction while requiring similar ultrasonic power and BSS volumes as the 1.1 mm TurboSonics tip with standard cassette and tubing. Together, they provide a wider available dynamic range in which to integrate ultrasonic power, higher vacuum, and higher aspiration flow rates to improve the efficiency and ease of use than the standard 1.1 mm TurboSonics cataract operation.

Cataract Extraction↗

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↗

PubMed1996

Comparison of photorefractive keratectomy for myopia using 5 mm and 6 mm diameter ablation zones.

BACKGROUND: We compared the 5 mm and 6 mm ablation zones of the Summit Omnimed in the treatment of myopia in 2 eyes of the same patient. METHOD: One hundred and twenty-four consecutive patients with myopia less than 6 diopters (D) has one eye treated with a 5 mm ablation zone and the other eye with a 6 mm ablation zone. Minimum follow up was 6 months. RESULTS: Follow-up was achieved in 101 patients of the total 124. In the 5 mm group 79% achieved 20/30 uncorrected visual acuity while 68% of the 6 mm group achieved 20/30 acuity. Ninety-seven percent of all eyes in both groups achieved 20/40. Some of the disparity between the 20/30 acuity in the two groups is that initial corrections with the 6 mm zones were conservative. Corneal haze was less in the 6 mm group; subjectively they had better night vision. CONCLUSIONS: Both lasers with the different ablation zones gave reasonably predictable correction of myopia of up to -6 D. Overcorrection and corneal haze were less in the 6 mm group and night vision was subjectively better.

Corneal Opacity↗

PubMed2004

A prospective randomized clinical trial comparing 2.0-mm locking plates to 2.0-mm standard plates in treatment of mandible fractures.

PURPOSE: The purpose of this study was to compare standard 2.0-mm monocortical plates to 2.0-mm locking plates in the treatment of mandible fractures. PATIENTS AND METHODS: A prospective randomized clinical trial was conducted at Harborview Medical Center in Seattle, WA, from January 1, 2002, to February 1, 2003, to compare 2.0-mm locking plates to 2.0-mm standard plates in treating consecutive mandible fractures. Patients were randomly assigned to receive locking 2.0-mm plates (group A) or nonlocking 2.0-mm plates (group B). Complications were divided into major and minor categories. Each complication was analyzed according to which plate was used and where the fracture occurred. The number of days from injury to operation, average age, gender, American Society of Anesthesiologists (ASA) classification,compliance, and social habits were all reviewed. RESULTS: Ninety patients with 122 fractures met the inclusion criteria. Sixty-four fracture sites were treated with locking plates and 58 with standard plates. A total of 6 complications occurred: 2 occurred at the angle, 3 at the parasymphysis, and 1 at the body. Three complications occurred in the locking group and 3 in the standard group with complication rates equaling 4.6% and 5.2%, respectively. When comparing the overall complication rates according to plates used, the Fisher exact test showed no statistically significant difference between the locking and standard plates (P = .90). The 95% confidence interval for the odds ratio is from 0.1 to 7. CONCLUSION: Mandible fractures treated with 2.0-mm locking plates and standard 2.0-mm plates present similar short-term complication rates.

Adolescent↗

PubMed2006

A biomechanical study comparing a raft of 3.5 mm cortical screws with 6.5 mm cancellous screws in depressed tibial plateau fractures.

There has been a recent trend towards using a raft of small diameter 3.5mm cortical screws for supporting depressed tibial plateau fractures (Schatzker type III). Our aim was to compare the biomechanical properties of a raft of 3.5 mm cortical screws with that of 6.5 mm cancellous screws in a synthetic bone model. Ten rigid polyurethane foam (sawbone) blocks, with a density simulating osteoporotic bone and ten blocks with a density simulating normal density bone were obtained. A Schatzker type III fracture was created in each block. The fracture fragments were then elevated and supported using two 6.5 mm cancellous screws in ten blocks and four 3.5 mm cortical screws in the remaining. The fractures were loaded using a Lloyd testing machine. The mean force needed to produce a depression of 5 mm was 700.8 N with the four-screw construct and 512.4 N with the two-screw construct in the osteoporotic model. This difference was highly statistically significant (p = 0.009). The mean force required to produce the same depression was 1878.2 N with the two-screw construct and 1938.2 N with the four-screw construct in the non-osteoporotic model. Though the difference was not statistically significant (p = 0.42), an increased fragmentation of the synthetic bone fragments was noticed with the two-screw construct but not with the four-screw construct. A raft of four 3.5 mm cortical screws is biomechanically stronger than two 6.5 mm cancellous screws in resisting axial compression in osteoporotic bone.

Biomechanical Phenomena↗