肱骨近端三维解剖结构的测量分析

目的利用多层螺旋CT容积再现技术测量国人肱骨近端三维解剖结构核心参数,比较性别和侧别的差异,为研制适用于国人解剖结构特点的新一代肱骨近端假体提供参考。方法征集重庆地区正常成年志愿者100例,男59例,女41例;年龄21～57岁,平均40.4岁。经多层螺旋CT扫描双侧肩峰至肱骨滑车末端后,将信息传送到LEONARDO工作站。利用容积再现技术测量前后扭转角(retroversion angle,RA)、股骨头倾斜角(neck-shaft angle,NSA)、向内的偏心距(medial offset,MO)和向后的偏心距(posterior offset,PO)。将测量结果进行左右侧、男女性别间比较,并分析参数间相关性。结果 100例200侧肩关节RA为(19.9±10.6)°,NSA为(134.7±3.8)°,MO为(4.0±1.1)mm,PO为(2.6±1.3)mm。RA及MO左、右侧比较,差异有统计学意义(P<0.05);NSA及PO左、右侧比较,差异无统计学意义(P>0.05)。男性双侧肩关节RA及PO均大于女性(P<0.05),NSA及MO均相似(P>0.05)。PO和RA成正相关(r=0.617,P=0.000),MO和NSA无相关性(r=—0.124,P=0.081)。结论 RA及MO存在侧别差异,不能用对侧测量值作为模板;RA和PO存在性别差异。假体设计和肱骨近端重建时,需注意考虑以上因素。     

Encouraging posttreatment self-help group involvement to reduce demand for continuing care services: two-year clinical and utilization outcomes

Background: Accumulating evidence indicates that addiction and psychiatric treatment programs that actively promote self‐help group involvement can reduce their patients' health care costs in the first year after treatment, but such initially impressive effects may wane over time. This paper examines whether the positive clinical outcomes and reduced health care costs evident 1 year after treatment among substance‐dependent patients who were strongly encouraged to attend 12‐step self‐help groups were sustained at 2‐year follow‐up. Methods: A 2‐year quasi‐experimental analysis of matched samples of male substance‐dependent patients who were treated in either 12‐step–based (n=887 patients) or cognitive‐behavioral (CB, n=887 patients) treatment programs. The 12‐step–based programs placed substantially more emphasis on 12‐step concepts, had more staff members “in recovery,” had a more spiritually oriented treatment environment, and promoted self‐help group involvement much more extensively than did the CB programs. The 2‐year follow‐up assessed patients' substance use, psychiatric functioning, self‐help group affiliation, and mental health care utilization and costs. Results: As had been the case in the 1‐year follow‐up of this sample, the only difference in clinical outcomes was a substantially higher abstinence rate among patients treated in 12‐step (49.5%) versus CB (37.0%) programs. Twelve‐step treatment patients had 50 to 100% higher scores on indices of 12‐step self‐help group involvement than did patients from CB programs. In contrast, patients from CB programs relied significantly more on outpatient and inpatient mental health services, leading to 30% lower costs in the 12‐step treatment programs. This was smaller than the difference in cost identified at 1 year, but still significant ($2,440 per patient, p=0.01). Conclusions: Promoting self‐help group involvement appears to improve posttreatment outcomes while reducing the costs of continuing care. Even cost offsets that somewhat diminish over the long term can yield substantial savings. Actively promoting self‐help group involvement may therefore be a useful clinical practice for helping addicted patients recover in a time of constrained fiscal resources.     

CEST phase mapping using a length and offset varied saturation (LOVARS) scheme

Chemical exchange saturation transfer MRI is a promising new technique for cellular and molecular imaging. This contrast allows the detection of tumors and ischemia without the use of gadolinium as well as the design of microenvironment‐sensitive probes that can be discriminated based on their exchange contrast properties and saturation frequency. Current acquisition schemes to detect and analyze this contrast suffer from sensitivity to spatial B₀ inhomogeneity and low contrast‐to‐noise‐ratio, which is an obstacle to widespread adoption of the technology. A new method to detect chemical exchange saturation transfer contrast is proposed here, termed “length and offset varied saturation” which acquires a set of images with the saturation parameters varied so as to modulate the exchange contrast. Either fast fourier transform or the general linear model can be employed to decompose the modulation patterns into separate sources of water signal loss. After transformation, a length and offset varied saturation phase map is generated, which is insensitive to B₀ inhomogeneity. When collected on live mice bearing 9L gliosarcomas, and compared to the conventional asymmetry in the magnetization transfer ratio map using offset increment correction, the results show that length and offset varied saturation phase mapping obtains about three to four times contrast‐to‐noise‐ratio and exhibits less B₀ artifacts. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.     

Influence of an unloader brace on lower limb electromyographic activity in individuals with predominant lateral osteoarthritis after anterior cruciate ligament reconstruction

ObjectiveTo determine the immediate effects of a varus unloader knee brace on lower-limb electromyographic activity in individuals with lateral knee osteoarthritis and valgus malalignment after anterior cruciate ligament reconstruction.MethodsElectromyographic data were recorded in 19 individuals with lateral knee osteoarthritis and valgus malalignment after anterior cruciate ligament reconstruction during walking under three conditions: (i) no brace, (ii) unadjusted brace (no varus adjustment), and adjusted brace (varus adjustment). Variables of interest were statistically analyzed using repeated measures analysis of variance.ResultsThere were no significant differences in muscle co-contraction between the three test conditions. The adjusted brace resulted in delayed offset of gluteus maximus (mean difference [95% CI]: 72 ms [24, 119]), and earlier onset of gluteus medius (59 ms [21, 97]) compared to no brace. The adjusted brace delayed onset of lateral gastrocnemius compared to no brace (53 ms [28, 78]) and the unadjusted brace (39 ms [7, 71]) and reduced average activation amplitude of gluteus maximus (−4 mV [−6, −1]) and lateral gastrocnemius (−9 mV [−16, −2]) compared to no brace.ConclusionsThe unloader brace did not produce significant changes in muscle co-contraction in individuals with lateral knee osteoarthritis and valgus malalignment after anterior cruciate ligament reconstruction. Significant changes in gluteal and gastrocnemius muscle activation timing and amplitude were observed, however, it is not clear whether these changes are of clinical importance.     

Kinetics and state-dependent effects of verapamil on cardiac L-type calcium channels

The voltage dependence and the kinetics of block by verapamil of L-type calcium current (I_Ca) were investigated in ventricular myocytes from rat hearts using the whole-cell patch-clamp technique. I_Ca was elicited repetitively in response to depolarizing voltage pulses from –80 mV to 0 mV at different pulse intervals and durations. Verapamil reduced the magnitude of I_Ca in a frequency-dependent manner without tonic component. The time course of I_Ca remained unchanged suggesting that not open but inactivated channels were affected by the drug. The interaction of verapamil with inactivated channels was investigated by the application of twin pulses. In the presence of verapamil, the duration of the first pulse significantly determined the magnitude of I_Ca during the second pulse. Variation of the duration of the first pulse between 12 and 3000 ms, followed by a pulse interval of 100 ms, resulted into a gradual decrease of I_Ca during the second pulse (180 ms), described by concentration-dependent monoexponential decay curves (t = 1060 ± 138 ms at 0.3 μM (n = 3); t = 310 ± 24 ms at 1 μM (n = 6), and t = 125 ± 7 ms at 10 μM (n = 5); means ± SEM). Under control conditions, the changes in I_Ca were comparably negligible. The recovery of I_Ca from block was analyzed by the application of a twin pulse protocol in which two depolarising voltage pulses at fixed length (1. pulse at 3 s and 2. pulse at 180 ms) were interrupted by variable pulse intervals (6 ms–60 s). Under control conditions, recovery from inactivation was fast (t = 11 ± 0.7 ms; means ± SEM; n = 3). In the presence of verapamil, recovery from block was about 500times slower than under control conditions, independent of the drug concentration (t = 5.05 ± 0.44 s at 0.3 μM (n = 3), t = 6.7 ± 0.69 s at 1 μM (n = 4), and t = 6.02 ± 0.9 s at 10 μM (n = 5); means ± SEM). Since development of block was dependent on the concentration of verapamil, whereas recovery from block was independent from the drug concentration, it is assumed that the described time constants for block and unblock reflect voltage-dependent net binding (τ_on) and unbinding (τ_off), respectively, of verapamil at its receptor sites. A computer simulation, including the time constants of block development at 0 mV and of recovery from block at –80 mV, predicted reasonably well the observed frequency-dependent block of I_Ca by verapamil. The development of either measured or calculated block of I_Ca, using 180 ms depolarising voltage pulses from –80 mV to 0 mV, was fitted by identical monoexponential association curves (t = 7 s each at 0.2 Hz and t = 1.7 s each at 1 Hz). When Ba²⁺ was used as the charge carrier, which removes the calcium-dependent inactivation of the current, verapamil (3 μM) was less efficient: I_Ca was decreased by 57 ± 6 % (means ± SEM; n = 6), whereas I_Ba was decreased by 24 ± 4 % (means ± SEM; n = 5). It is proposed that verapamil binds to calcium channels in their inactivated state at more positive potentials and dissociates from the channels in the resting state at more negative potentials. In the proposed scheme of periodical drug binding and unbinding, dependent on the state of the channels, the development of frequency-dependent block of I_Ca by verapamil is adequately predicted by the construction of cumulative association/dissociation curves which include the experimentally determined time constants of development and recovery from block at 0 mV and –80 mV, respectively. Received: 17 May 1996 / Accepted: 23 September 1996     

Effect and Offset of Effect of Treatments for Hip Fracture on Health Outcomes

We investigated the cost-effectiveness of treatments that reduce the risk of hip fracture using a computer simulation model. Cost-effectiveness was measured as cost per quality-adjusted life-year (QALY) gained using a threshold value for cost-effectiveness of $30.000/QALY gained. The baseline simulations assumed a 5-year intervention that reduced the risk of hip fracture by 50% during the intervention period, and an effect which reversed to the pretreatment risk during the next 5 years. Sensitivity analyses inlcuded the effects of age, different fracture risks, and different treatment costs and duration of therapeutic effect once treatment was stopped. Cost-effectiveness was critically dependent upon absolute risk determined by the age and the relative risk of hip fracture at any given age. Reasonable cost-effectiveness was shown even with relatively high intervention costs for women with a risk about twice the average at the age of 70 or more years. Cost-effectiveness was critically dependent upon the assumptions made concerning offset of effect of intervention after the end of treatment. Where no residual effect was assumed, it was difficult to show cost-effectiveness from any intervention except for the most effective and least expensive. Conversely, cost-effectiveness improved considerably where effectiveness persisted for a longer time. These studies support the view that intervention in the elderly with agents affecting skeletal metabolism alone may be preferred to such interventions at the time of the menopause, and that offset time, hitherto poorly characterized, is a critical component of cost-effectiveness, particularly in younger women. Received: 26 May 1998 / Accepted: 8 February 1999     

Digital templating in total hip arthroplasty with the Mayo stem

Patients  In 40 patients undergoing total hip arthroplasty with the Mayo femoral stem we studied how preoperative digital templating corresponded to the actual intraoperative choice of implant size, position, offset and restoration of leg length. Results  The preoperatively planned sizes of the components showed a high rate of coincidence with the sizes used intraoperatively [Intraclass Correlation Coefficient (ICC) 0.661–0.810]. However, the agreements in offset and CCD correction were poor (ICC 0.476, 0.253). This could be statistically attributed to the change in the distance from the medial margin of the stem to the medial margin of the medial femoral cortex and the height of osteotomy. The agreement in leg length correction was moderate (ICC 0.583), which was attributed to the change in the hip rotation center and the height of osteotomy. Conclusion  Careful preoperative planning was useful for accurate size choice of the Mayo prosthesis. Factors such as the height of osteotomy and the distance from the medial margin of the stem to the medial margin of the medial femoral cortex in relation to the position of the Mayo stem should be taken into account in order to restore ideal offset and leg length.     

Duofit total hip arthroplasty: a medium- to long-term clinical and radiographic evaluation

We report the retrospective analysis of 716 cases of Duofit total hip arthroplasty performed from 1994 to 2005. Since 2004, both standard and lateralized stems were used, while previously only the standard type was available. The results show a low occurrence of complications and a good medium-to long-term survival. The good functional outcome, measured with the Harris hip score, confirms the validity of the prosthetic design and materials.     

Differential effects of experimental central sensitization on the time-course and magnitude of offset analgesia

Pain perception is temporally altered during states of chronic pain and acute central sensitization; however, the mechanisms contributing to temporal processing of nociceptive information remain poorly understood. Offset analgesia is a phenomenon that reflects the presence of temporal contrast mechanisms for nociceptive information and can provide an end point to study temporal aspects of pain processing. In order to investigate whether offset analgesia is disrupted during sensitized states, 23 healthy volunteers provided real-time continuous visual analogue scale responses to noxious heat stimuli that evoke offset analgesia. Responses to these stimuli were evaluated during capsaicin-heat sensitization (45°C stimulus, capsaicin cream 0.1%) and heat-only sensitization (40°C stimulus, placebo cream). Capsaicin-heat sensitization produced significantly larger regions of secondary mechanical allodynia compared to heat-only sensitization. Although areas of mechanical allodynia were positively related to individual differences in heat pain sensitivity, this relationship was altered at later time points after capsaicin-heat sensitization. Heat hyperalgesia was observed in the secondary region following both capsaicin-heat and heat-only sensitization. Increased latencies to maximal offset analgesia and prolonged aftersensations were observed only in the primary regions directly treated by capsaicin-heat or heat alone. However, contrary to the hypothesis that offset analgesia would be reduced following capsaicin-heat sensitization, the magnitude of offset analgesia remained remarkably intact after both capsaicin-heat and heat-only sensitization in zones of both primary and secondary mechanical allodynia. These data indicate that offset analgesia is a robust phenomenon and engages mechanisms that interact minimally with those supporting acute central sensitization.     

A study of the performance of a modified V-shaped solids mixer using segregating materials

A binary free-flowing mixture made up of 30% salt and 70% non-pareil seeds was used as a mixing model. The performance of the mixer was defined in terms of relative standard deviation from the measured mean and the percent of the discharge profile within a 5% limit. The variables investigated in the present study included the leg reduction (0, 10, 20, 40 and 60%), offset angle (0, 15, 30, 45, 60, 75 and 90°), mixing time (0, 1, 5, 10, 15 and 30 min) and any combination of the afore-mentioned variables. The study confirms that the V-shaped blender can be improved upon by using an uneven leg (10–20% reduction) and an offset angle (15°). A combination of a 40% leg reduction and 75 or 90° offset angle gave the best results and that of a 0% leg reduction and 90° offset angle produced the worst results.