Results of computer assisted navigation in Total Knee Arthroplasty (TKA): comparison with the conventional method

The aim of this retrospective study was to compare the clinical and radiographic results after TKA (PFC, DePuy), performed either by computer assisted navigation (CAS, Brainlab, Johnson&Johnson) or by conventional means. Material and methods: Between May and December 2006 we reviewed 36 conventional TKA performed between 2002 and 2003 (group A) and 37 navigated TKA performed between 2005 and 2006 (group B) by the same experienced surgeon. The mean age in group A was 74 years (range 62-90) and 73 (range 58-85) in group B with a similar age distribution. The preoperative mechanical axes in group A ranged from -13° varus to +13° valgus (mean absolute deviation 6.83°, SD 3.86), in group B from -13° to +16° (mean absolute deviation 5.35, SD 4.29). Patients with a previous tibial osteotomy or revision arthroplasty were excluded from the study. Examination was done by an experienced orthopedic resident independent of the surgeon. All patients had pre- and postoperative long standing radiographs. The IKSS and the WOMAC were utilized to determine the clinical outcome. Patient's degree of satisfaction was assessed on a visual analogous scale (VAS). Results: 32 of the 37 navigated TKAs (86,5%) showed a postoperative mechanical axis within the limits of 3 degrees of valgus or varus deviation compared to only 24 (66%) of the 36 standard TKAs. This difference was significant (p = 0.045). The mean absolute deviation from neutral axis was 3.00° (range -5° to +9°, SD: 1.75) in group A in comparison to 1.54° (range -5° to +4°, SD: 1.41) in group B with a highly significant difference (p = 0.000). Furthermore, both groups showed a significant postoperative improvement of their mean IKSS-values (group A: 89 preoperative to 169 postoperative, group B 88 to 176) without a significant difference between the two groups. Neither the WOMAC nor the patient's degree of satisfaction - as assessed by VAS - showed significant differences. Operation time was significantly higher in group B (mean 119.9 min.) than in group A (mean 99.6 min., p <0.000). Conclusion: Our study showed consistent significant improvement of postoperative frontal alignment in TKA by computer assisted navigation (CAS) compared to standard methods, even in the hands of a surgeon well experienced in standard TKA implantation. However, the follow-up time of this study was not long enough to judge differences in clinical outcome. Thus, the relevance of computer navigation for clinical outcome and survival of TKA remains to be proved in long term studies to justify the longer operation time. References 1 Stulberg SD. Clin Orth Rel Res. 2003;(416):177-84. 2 Chauhan SK. JBJS Br. 2004;86(3):372-7. 3 Bäthis H, et al. Orthopäde. 2006;35(10):1056-65.

Objective analysis of gait coordination for total knee arthroplasty outcome

Introduction: Coordination is a strategy chosen by the central nervous system to control the movements and maintain stability during gait. Coordinated multi-joint movements require a complex interaction between nervous outputs, biomechanical constraints, and pro-prioception. Quantitatively understanding and modeling gait coordination still remain a challenge. Surgeons lack a way to model and appreciate the coordination of patients before and after surgery of the lower limbs. Patients alter their gait patterns and their kinematic synergies when they walk faster or slower than normal speed to maintain their stability and minimize the energy cost of locomotion. The goal of this study was to provide a dynamical system approach to quantitatively describe human gait coordination and apply it to patients before and after total knee arthroplasty. Methods: A new method of quantitative analysis of interjoint coordination during gait was designed, providing a general model to capture the whole dynamics and showing the kinematic synergies at various walking speeds. The proposed model imposed a relationship among lower limb joint angles (hips and knees) to parameterize the dynamics of locomotion of each individual. An integration of different analysis tools such as Harmonic analysis, Principal Component Analysis, and Artificial Neural Network helped overcome high-dimensionality, temporal dependence, and non-linear relationships of the gait patterns. Ten patients were studied using an ambulatory gait device (Physilog®). Each participant was asked to perform two walking trials of 30m long at 3 different speeds and to complete an EQ-5D questionnaire, a WOMAC and Knee Society Score. Lower limbs rotations were measured by four miniature angular rate sensors mounted respectively, on each shank and thigh. The outcomes of the eight patients undergoing total knee arthroplasty, recorded pre-operatively and post-operatively at 6 weeks, 3 months, 6 months and 1 year were compared to 2 age-matched healthy subjects. Results: The new method provided coordination scores at various walking speeds, ranged between 0 and 10. It determined the overall coordination of the lower limbs as well as the contribution of each joint to the total coordination. The difference between the pre-operative and post-operative coordination values were correlated with the improvements of the subjective outcome scores. Although the study group was small, the results showed a new way to objectively quantify gait coordination of patients undergoing total knee arthroplasty, using only portable body-fixed sensors. Conclusion: A new method for objective gait coordination analysis has been developed with very encouraging results regarding the objective outcome of lower limb surgery.

Effectiveness of three different walking prescription durations on total physical activity in normal- and overweight women.

OBJECTIVE: While there is a dose-response relationship between physical activity (PA) and health benefit, little is known about the effectiveness of different PA prescriptions on total daily PA. AIM: To test, under real-life conditions and using an objective, non-invasive measurement technique (accelerometry), the effect of prescribing additional physical activity (walking only) of different durations (30, 60 and 90 min/day) on compliance (to the activity prescribed) and compensation (to total daily PA). Participants in each group were prescribed 5 sessions of walking per week over 4 weeks. METHODS: 55 normal-weight and overweight women (mean BMI 25 ± 5 kg/m(2), height 165 ± 1 cm, weight 68 ± 2 kg and mean age 27 ± 1 years) were randomly assigned to 3 prescription groups: 30, 60 or 90 min/day PA. RESULTS: Walking duration resulted in an almost linear increase in the number of steps per day during the prescription period from an average of about 10,000 steps per day for the 30-min prescription to about 14,000 for the 90-min prescription. Compliance was excellent for the 30-min prescription but decreased significantly with 60-min and 90-min prescriptions. In parallel, degree of compensation subsequent to exercise increased progressively as length of prescription increased. CONCLUSION: A 30-min prescription of extra walking 5 times per week was well tolerated. However, in order to increase total PA further, much more than 60 min of walking may need to be prescribed in the majority of individuals. While total exercise 'volume' increased with prescriptions longer than 30 min, compliance to the prescription decreased and greater compensation was evident. © 2014 S. Karger GmbH, Freiburg.

Indicators for the total number of melanocytic naevi : an adjunct for screening campaigns. Observational study on 292 patients.

BACKGROUND: The presence of multiple melanocytic naevi is a strong risk factor for melanoma. Use of the whole body naevus count to identify at-risk patients is impractical. OBJECTIVES: To (i) identify a valid anatomical predictor of total naevus count; (ii) determine the number of naevi that most accurately predict total naevus count above 25, 50 and 100; and (iii) evaluate determinants of multiple melanocytic naevi and atypical naevi. METHODS: Clinical data from 292 consecutive Spanish patients consulting for skin lesions requiring debriding were collected throughout 2009 and 2010. Correlations between site-specific and whole body naevus counts were analysed. Cut-offs to predict total naevus counts were determined using the area under the receiver operating characteristic curve. RESULTS: The studied population was young (median age 31 years, interquartile range 28-43). The naevus count on the right arm correlated best with the total nevus count (R(2) 0·80 for men, 0·86 for women). Presence of at least five naevi on the right arm was the strongest determinant of a total naevus count above 50 [odds ratio (OR) 34·4, 95% confidence interval (CI) 13·9-85·0] and of having at least one atypical naevus (OR 5·7, 95% CI 2·4-13·5). Cut-off values of 6, 8 and 11 naevi on the right arm best predicted total naevus count above 25, 50 and 100, respectively. CONCLUSIONS: Our results support the arm as a practical and reliable site to estimate the total naevus count when screening or phenotyping large populations. Threshold values for the number of naevi on the arm are proposed to help identify patients for melanoma screening.

Validity of impedance-based equations for the prediction of total body water as measured by deuterium dilution in African women.

BACKGROUND: Little information is available on the validity of simple and indirect body-composition methods in non-Western populations. Equations for predicting body composition are population-specific, and body composition differs between blacks and whites. OBJECTIVE: We tested the hypothesis that the validity of equations for predicting total body water (TBW) from bioelectrical impedance analysis measurements is likely to depend on the racial background of the group from which the equations were derived. DESIGN: The hypothesis was tested by comparing, in 36 African women, TBW values measured by deuterium dilution with those predicted by 23 equations developed in white, African American, or African subjects. These cross-validations in our African sample were also compared, whenever possible, with results from other studies in black subjects. RESULTS: Errors in predicting TBW showed acceptable values (1.3-1.9 kg) in all cases, whereas a large range of bias (0.2-6.1 kg) was observed independently of the ethnic origin of the sample from which the equations were derived. Three equations (2 from whites and 1 from blacks) showed nonsignificant bias and could be used in Africans. In all other cases, we observed either an overestimation or underestimation of TBW with variable bias values, regardless of racial background, yielding no clear trend for validity as a function of ethnic origin. CONCLUSIONS: The findings of this cross-validation study emphasize the need for further fundamental research to explore the causes of the poor validity of TBW prediction equations across populations rather than the need to develop new prediction equations for use in Africa.

Outcomes and reoperations after total correction of complete atrio-ventricular septal defect

BACKGROUND: Surgical correction of complete atrio-ventricular septal defect (AVSD) achieves satisfactory results with low morbidity and mortality, but may require reoperation. Our recent operative results at mid-term were followed-up. METHODS: From June 2000 to December 2007, 81 patients (Down syndrome; n=60), median age 4.0 months (range 0.7-118.6) and weight 4.7kg (range 2.2-33), underwent complete AVSD correction. Patch closure for the ventricular septal defect (VSD; n=69) and atrial septal defect (ASD; n=42) was performed with left atrio-ventricular valve (LAVV) cleft closure (n=76) and right atrio-ventricular valve (RAVV) repair (n=57). Mortality, morbidity, and indications for reoperation were retrospectively studied; the end point 'time to reoperation' was analyzed using Kaplan-Meier curves. Follow-up was complete except in two patients and spanned a median of 28 months (range 0.4-6.1 years). RESULTS: In-hospital mortality was 3.7% (n=3) and one late death occurred. Reoperation was required in 7/79 patients (8.9%) for LAVV insufficiency (n=4), for a residual ASD (n=1), for right atrio-ventricular valve insufficiency (n=1), and for subaortic stenosis (n=1). At last follow-up, no or only mild LAVV and RAVV insufficiency was present in 81.3% and 92.1% of patients, respectively, and 2/3 of patients were medication-free. Risk factors for reoperation were younger age (<3 months; p=0.001) and lower weight (<4kg; p=0.003), and a trend towards less and later reoperations in Down syndrome (p<0.2). CONCLUSIONS: Surgical correction of AVSD can be achieved with low mortality and need for reoperation, regardless of Down syndrome or not. Immediate postoperative moderate or more residual atrio-ventricular valve insufficiency will eventually require a reoperation, and could be anticipated in patients younger than 3 months and weighing <4kg.

Total IgE and eotaxin (CCL11) contents in tears of patients suffering from seasonal allergic conjunctivitis.

BACKGROUND: To prospectively investigate patients with seasonal allergic conjunctivitis (SAC) during the pollen season and test associations between tears total IgE, eotaxin concentrations, and SAC severity. METHODS: Enrolled patients presented ocular symptoms and clinical signs of SAC at the time of presentation. Ocular itching, hyperaemia, chemosis, eyelid swelling, and tearing were scored, and the sum of these scores was defined as the clinical score. Conjunctival papillae were separately graded. We measured eotaxin concentration in tears by an enzyme-linked immunosorbent assay (ELISA) and total tear IgE by Lacrytest strip. RESULTS: Among thirty patients (30 eyes), 11 showed neither tear IgE nor tear eotaxin, while 15 out of 19 patients with positive IgE values presented a positive amount of eotaxin in their tears (Fisher's test: p < 0.001). The mean eotaxin concentration was 641 ± 154 (SEM) pg/ml. In patients with no amount of tear IgE, we observed a lower conjunctival papilla grade than in patients whose tears contained some amount of IgE (trend test: p = 0.032). In the 15 patients whose tear eotaxin concentration was null, tear IgE concentration was 5.3 ± 3.5 arbitrary units; in the other 15 patients whose eotaxin was positive, IgE reached 21 ± 4.3 arbitrary U (Mann-Whitney: p < 0.001). We measured 127 ± 47 pg/ml eotaxin in patients with no history of SAC but newly diagnosed as suffering from SAC, and 852 ± 218 pg/ml eotaxin in patients with a known SAC (p = 0.008). In contrast, tear IgE concentrations of both groups did not differ statistically significantly (p = 0.947). CONCLUSIONS: If IgE and eotaxin secreted in tears are major contributors in SAC pathogenesis, they however act at different steps of the process.

Normal glucagon signaling and β-cell function after near-total α-cell ablation in adult mice.

OBJECTIVEEvaluate whether healthy or diabetic adult mice can tolerate an extreme loss of pancreatic α-cells and how this sudden massive depletion affects β-cell function and blood glucose homeostasis.RESEARCH DESIGN AND METHODSWe generated a new transgenic model allowing near-total α-cell removal specifically in adult mice. Massive α-cell ablation was triggered in normally grown and healthy adult animals upon diphtheria toxin (DT) administration. The metabolic status of these mice was assessed in 1) physiologic conditions, 2) a situation requiring glucagon action, and 3) after β-cell loss.RESULTSAdult transgenic mice enduring extreme (98%) α-cell removal remained healthy and did not display major defects in insulin counter-regulatory response. We observed that 2% of the normal α-cell mass produced enough glucagon to ensure near-normal glucagonemia. β-Cell function and blood glucose homeostasis remained unaltered after α-cell loss, indicating that direct local intraislet signaling between α- and β-cells is dispensable. Escaping α-cells increased their glucagon content during subsequent months, but there was no significant α-cell regeneration. Near-total α-cell ablation did not prevent hyperglycemia in mice having also undergone massive β-cell loss, indicating that a minimal amount of α-cells can still guarantee normal glucagon signaling in diabetic conditions.CONCLUSIONSAn extremely low amount of α-cells is sufficient to prevent a major counter-regulatory deregulation, both under physiologic and diabetic conditions. We previously reported that α-cells reprogram to insulin production after extreme β-cell loss and now conjecture that the low α-cell requirement could be exploited in future diabetic therapies aimed at regenerating β-cells by reprogramming adult α-cells.

Influence of inflammation on total energy expenditure in hemodialysis patients.

Background and Objectives: Studies show that inflammation can contribute to an increase in resting energy expenditure in patients with chronic kidney disease; however, findings about total energy expenditure (TEE) have not been reported. The aim of this study was to evaluate the effects of inflammation on TEE and physical activity energy expenditure in hemodialysis (HD) patients.Design: This was a cross-sectional study.Setting: This study was conducted from Hopital Edouard Herriot, Lyon, France.Patients: This study included 24 HD patients and 18 healthy subjects.Main Outcome Measure: TEE and step counts were measured over a 7-day period by the SenseWear Pro2 Armband in 24 HD patients (15 patients with C-reactive protein,5 mg/L, aged 67.0 +/- 6 14.7 years, and 9 with C-reactive protein >5 mg/L, aged 69.0 +/- 6 18.0 years) and compared with 18 healthy subjects (62.3 +/- 6 15.3 years).Results: Mean estimated TEE measured with SenseWear Pro2 Armband was significantly lower (25.5 +/- 4.1 kcal/kg/day) in patients with inflammation when compared with those without inflammation (32.0 +/- 6.7 kcal/kg/day) and with healthy subjects (31.8 +/- 6 7.0 kcal/kg/day) (P = .012). There was a difference in the physical activity (step counts) between patient groups (P < .05). Healthy subjects and patients without inflammation walked more (8,107 +/- 5,419 and 6,016 +/- 3,752 steps/day, respectively) as compared with patients with inflammation (2,801 +/- 2,754 steps/day, P = .001).Conclusion: Our findings suggest that patients with inflammation have a lower TEE when compared with healthy subjects and patients without inflammation. TEE is influenced by physical activity because patients with inflammation appear to be less active. (C) 2011 by the National Kidney Foundation, Inc. All rights reserved.

Does previous hip arthroscopy negatively influence the short term clinical result of total hip replacement?

INTRODUCTION: The risk that hip preserving surgery may negatively influence the performance and outcome of subsequent total hip replacement (THR) remains a concern. The aim of this study was to identify any negative impact of previous hip arthroscopy on THR. METHODS: Out of 1271 consecutive patients who underwent primary THR between 2005 and 2009, 18 had previously undergone ipsilateral hip arthroscopy. This study group (STG) was compared with two control groups (CG, same approach, identical implants; MCG, paired group matched for age, BMI and Charnley categories). Operative time, blood loss, evidence of heterotopic bone and implant loosening at follow-up were compared between the STG and the MCG. Follow-up WOMAC were compared between the three groups. RESULTS: Blood loss was not found to be significantly different between the STG and MCG. The operative time was significantly less (p < 0.001) in the STG. There was no significant difference in follow-up WOMAC between the groups. No implant related complications were noted in follow-up radiographs. Two minor complications were documented for the STG and three for the MCG. CONCLUSION: We have found no evidence that previous hip arthroscopy negatively influences the performance or short-term clinical outcome of THR.