Malrotation in total knee arthroplasty: effect on tibial cortex strain captured by laser-based strain acquisition

BACKGROUND: Malrotation of the tibial and femoral components has been recognized to be a clinical complication affecting the performance and durability of total knee arthroplasty. This study used a novel strain acquisition technique to determine the effect of tibio-femoral component malrotation on tibial torque and strain distribution of the proximal tibial cortex with a cemented fixed-bearing posterior-stabilized knee. METHODS: Using electronic speckle pattern interferometry, strain on the proximal tibia of human cadaveric knees was obtained in response to 1500N axial loading for neutrally aligned tibial and femoral components, and for 10 degrees internal and external malrotation between the tibial and femoral components. Local strain gage measurements were combined with full-field optical strain measurements to quantify effects on tibial cortex strain and strain distributions caused by the 10 degrees malrotations. In addition, tibial torque was measured for incremental degrees of tibio-femoral malrotation. FINDINGS: Tibio-femoral malrotations as small as 2 degrees caused tibial torque in excess of 4 Nm. At 10 degrees malrotation, tibial torque significantly increased to over 8 Nm (P<0.001) as compared to neutrally aligned components. Local strain gage results significantly increased from 500 muepsilon to 632 muepsilon compressive strain in response to 10 degrees external malrotation, and to 1000 muepsilon compressive strain in response to 10 degrees internal malrotation. Full-field optical strain reports yielded the highest strain of 2153 muepsilon for 10 degrees internal malrotation 30 mm below the joint line. INTERPRETATION: Laser-based strain measurement technology provides novel capabilities to capture cortex strain fields. The sensitivity of cortex strain and torsion to small amounts of tibio-femoral malrotation may explain factors contributing to aseptic implant loosening of the tibial component.     

S-Allylcysteine prevents amyloid-beta peptide-induced oxidative stress in rat hippocampus and ameliorates learning deficits

The effects of S-allylcysteine on oxidative damage and spatial learning and memory deficits produced by an intrahippocampal injection of amyloid-beta peptide 25-35 (Abeta(25-35)) in rats were investigated. The formation of reactive oxygen species, lipid peroxidation and the activities of the antioxidant enzymes superoxide dismutase and glutathione peroxidase were all measured in hippocampus 120 min after Abeta(25-35) injection (1 microl of 100 microM solution), while learning and memory skills were evaluated 2 and 35 days after the infusion of Abeta(25-35) to rats, respectively. Abeta(25-35) increased both reactive oxygen species and lipid peroxidation, whereas pretreatment with S-allylcysteine (300 mg/kg, i.p.) 30 min before peptide injection decreased both of these markers. In addition, Abeta(25-35)-induced incorrect learning responses were prevented in most of trials by S-allylcysteine. In contrast, enzyme activities were found unchanged in all groups tested. Findings of this work: (i) support the participation of reactive oxygen species in Abeta(25-35)-induced hippocampal toxicity and learning deficits; and (ii) suggest that the protective effects of S-allylcysteine were related to its ability to scavenge reactive oxygen species.     

Total laparoscopic hysterectomy: a new option for removal of the large myomatous uterus

This is the first report of a series of women who underwent total laparoscopic hysterectomy (TLH) to remove a large myomatous uterus weighing more than 390 g. The case history notes of 21 women undergoing TLH in both the private and public sectors of Flinders Endogynaecology were studied. The mean uterine weight was 534.7 g (390-1,022 g). The mean operating time was 155.0 +/- 56.1 minutes and mean blood loss was 297.6 mL (50-1,000 mL). The mean hospital stay was 3.2 +/- 1.0 days. The two complications were a post-operative deep venous thrombosis (DVT) and an estimated blood loss of 1000 mL in separate cases. Total laparoscopic hysterectomy is a low morbidity procedure offering a new option for the removal of the large myomatous uterus and avoidance of abdominal hysterectomy     

Two-year experience with laparoscopic pelvic floor repair

STUDY OBJECTIVE: To evaluate the cumulative experience at our institution of laparoscopic pelvic floor repair to treat genital prolapse and associated symptoms. DESIGN: Retrospective analysis (Canadian Task Force classification II-2). SETTING: University hospital. PATIENTS: Seventy-three consecutive women treated surgically for symptomatic genital prolapse. INTERVENTION: Surgical treatment was site specific depending on findings on physical examination. Anterior compartment defects were treated by laparoscopic paravaginal repair, laparoscopic Burch colposuspension, or transvaginal anterior vaginal repair. Defects in the posterior compartment were treated by a combination of laparoscopic supralevator repair, laparoscopic vaginal vault suspension, enterocele sac invagination or excision, and transvaginal posterior vaginal repair. Anatomic defects in the apical compartment were primarily treated by laparoscopic vaginal vault suspension and enterocele sac excision. Patients whose anatomic anomalies contained elements of anterior, posterior, and apical compartments were classified in a global group. MEASUREMENTS AND MAIN RESULTS: Preoperatively, prolapse was considered as an attachment or fascial defect at DeLancey level I, II, or III. Each was then quantified by the pelvic organ prolapse quantification (POPQ) system and compartmentalized according to site of the major defect. Women were assessed by physical examination and repeat POPQ staging 6 weeks postoperatively and every 6 months thereafter. A standard interview was administered to assess functional status. Major complications occurred in 4.1% of women. Objective and subjective cure rates were 90% at 2 years. CONCLUSIONS: Laparoscopic pelvic floor repair is an effective procedure with low morbidity. It should play a primary role in surgical management of DeLancey levels I and II attachment defects. For fascial defects, in particular DeLancey level II anteriorly and posteriorly, it should be complemented with vaginal repair.     

PCR detection of clonal IgH and TCR gene rearrangements at the end of induction as a non-remission criterion in children with ALL: comparison with standard morphologic analysis and risk group classification

BACKGROUND: The initial response to induction therapy is currently considered one of the most important prognostic factors in acute lymphoblastic leukemias (ALL). A series of methods for the detection of submicroscopic levels of residual disease in patients with ALL mainly based on PCR and immunophenotyping has been developed, demonstrating that the presence of high levels of residual disease at the end of induction therapy is an important, independent prognostic factor. We determined the usefulness of PCR detection of minimal residual disease using consensus primers as a non-remission criterion. PROCEDURE: Bone marrow samples obtained from 49 children with ALL were analyzed at diagnosis and at the end of induction therapy for the detection of clonal IgH, TCRdelta, and TCRgamma rearrangements by PCR. The results were compared with those obtained by standard morphologic analysis and risk group classification. RESULTS: Patients who had clonality detected at the end of induction showed a significantly higher recurrence rate and lower event-free survival than those without detected clonality (24.9% vs. 89.7%) (P < 0.0001). Multivariate analysis revealed that detection of clonality at the end of induction was the most important, independent prognostic factor when associated with age, number of white blood cells, and immunophenotyping. CONCLUSIONS: PCR detection of clonality using consensus primers is a relatively simple technique that is able to identify patients with a high chance of recurrence, and shows a higher sensitivity and a better prognostic value than standard morphologic analysis and risk group classification, defining a new remission criterion. However, further multicentric prospective studies using this technique employing a larger number of cases are necessary to confirm these findings.     

Sequential ablation approach to the correction of mixed astigmatism

PURPOSE: To evaluate the safety, efficacy, and stability of LASIK, using positive cylinder and negative sphere nomograms in sequence (sequential ablation) to correct mixed astigmatism. METHODS: This prospective study included 40 eyes of 20 patients with mixed astigmatism. Patients underwent bilateral sequential ablation LASIK using the Technolas 217 excimer laser (Bausch & Lomb Surgical, Rochester, NY). The main outcome measures, uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA), were evaluated 3 and 12 months after surgery. RESULTS: Preoperative astigmatism ranged from +1.75 to +6.00 diopters (D) and negative sphere from -0.50 to -3.00 D. The postoperative refraction at 3 months remained unchanged at 1 year postoperative in all patients. A total of 32 (80%) eyes showed no significant residual astigmatism (<0.50 D); the remaining 8 (20%) eyes had 0.50 to 1.00 D of residual astigmatism. Residual negative sphere was present in 2 eyes of 2 patients with a planned monovision target. In the remaining 38 (95%) eyes, no significant residual negative sphere was present. Sixteen (40%) eyes had one line of improvement in BSCVA. No eye lost lines of visual acuity. The efficacy index shows that uncorrected vision after surgery is equal or better than corrected vision before surgery. Less corneal tissue is removed and fewer laser spots are required compared to other techniques for the correction of mixed astigmatism. CONCLUSIONS: The sequential ablation approach to the correction of mixed astigmatism was efficacious, safe, and stable 1 year after surgery.     

Accuracy of the Lang II stereotest in screening for binocular disorders in 6-year-old children

PURPOSE: To assess the accuracy of the Lang II stereotest in screening for strabismus, amblyopia, and anisometropia in 6-year-old children. DESIGN: Cross-sectional population-based study. METHODS: The Sydney Myopia Study examined 1765 6-year-old children (78.9% of eligible) who were identified by random cluster sampling of 34 schools in Sydney, Australia. Sensitivity and specificity of the Lang II stereotest was determined by best stereoacuity. Cycloplegic autorefraction, assessment of visual acuity, and ocular motility were conducted. RESULTS: Test sensitivity ranged from 21.4% for anisometropia (> or =1.0 diopter) to 31.3% for amblyopia. The detection rate for new cases of amblyopia ranged from 20% to 40%; the detection rate for new cases of strabismus was 30%. Specificity was >98% in all three conditions. Children with false-negative results included newly diagnosed cases of strabismus (14 of 25 children) or amblyopia (5 of 12 children). CONCLUSION: The Lang II stereotest, when used alone, has very limited value as a screening test of binocular dysfunction.     

Effect of stature and other anthropometric parameters on eye size and refraction in a population-based study of Australian children

PURPOSE: To determine the effect of anthropometric parameters on refraction and ocular biometry. METHODS: Noncontact methods were used to examine ocular dimensions and cycloplegic refraction in a stratified random cluster sample of year-1 Sydney school students (mean age, 6 years; n = 1765). Height, body weight, and waist circumference were measured according to a standardized protocol. Body mass index (BMI) was subsequently calculated. The percentage of body fat was measured with leg-leg bioelectrical impedance analysis. Associations between parameters were analyzed by multiple linear regression. RESULTS: After adjustment for age in weeks, height was found to be strongly associated with axial length and corneal radius. Children in the 1st quintile for height had axial length of 22.39 +/- 0.04 mm compared with 22.76 +/- 0.04 mm in children in the 5th quintile. Other anthropometric parameters were not associated with axial length or corneal radius. Height was not associated with anterior chamber depth after adjustment for weight. Increases in weight, BMI, and waist circumference were associated with a deeper anterior chamber after adjustment for height. No associations were found between the measured anthropometric parameters and refraction or axial length-corneal radius ratio. CONCLUSIONS: This study found a strong association between height and axial length and corneal radius, but not spherical equivalent refraction. The findings may demonstrate the effectiveness of emmetropization in the presence of normal physiological influences.     

Methods for a population-based study of myopia and other eye conditions in school children: the Sydney Myopia Study

PURPOSE: The Sydney Myopia Study will establish the prevalence of myopia and other eye diseases in a large representative sample of Sydney school children. It will also examine the relationship between myopia and potential modifiable risk factors and will assess potential gene-environment interactions by examining parents and siblings. METHODS: The target population is a stratified random cluster sample of 1750 Year 1 (age 6 years) and 1500 Year 7 (age 12 years) students from Sydney metropolitan schools. Procedures (comprehensive parent-administered questionnaire and examination) involve standardized protocols to allow for comparison with international population-based data. Examinations include a detailed assessment of visual acuity, cover testing for strabismus, identification of amblyopia, slit-lamp examination, non-contact ocular biometry and cycloplegia (cyclopentolate) followed by autorefraction, optical coherence tomography, retinal thickness measurement, digital mydriatic retinal photography and aberrometry. CONCLUSIONS: The Sydney Myopia Study design and methodology will ensure valid findings on ocular development and health in a large representative sample of Sydney school children, for comparison with other population-based refraction data.     

Laser surface scanning for patient registration in intracranial image-guided surgery

OBJECTIVE: To report our clinical experience with a new laser scanning-based technique of surface registration. We performed a prospective study to measure the calculated registration error and the application accuracy of laser surface registration for intracranial image-guided surgery in the clinical setting. METHODS: Thirty-four consecutive patients with different intracranial diseases were scheduled for intracranial image-guided surgery by use of a passive infrared surgical navigation system. Surface registration was performed by use of a Class I laser device that emits a visible laser beam. The Polaris camera system (Northern Digital, Waterloo, ON, Canada) detects the skin reflections of the laser, which the software uses to generate a virtual three-dimensional matrix of the anatomy of each patient. An advanced surface-matching algorithm then matches this virtual three-dimensional matrix to the three-dimensional magnetic resonance therapy data set. Registration error as calculated by the computer was noted. Application accuracy was assessed by use of the localization error for three distant anatomic landmarks. RESULTS: Laser surface registration was successful in all patients. For the surgical field, application accuracy was 2.4 +/- 1.7 mm (range, 1-9 mm). Application accuracy was higher for the surgical field of frontally located lesions (mean, 1.8 +/- 0.8 mm; n = 13) as compared with temporal, parietal, occipital, and infratentorial lesions (mean, 2.8 +/- 2.1 mm; n = 21). CONCLUSION: Laser scanning for surface registration is an accurate, robust, and easy-to-use method of patient registration for image-guided surgery.