Analysis of vertical and horizontal offsets in displaced femoral neck fracture in elderly treated with indigenous bicentric bipolar hip device

ObjectivesTo analyze the effect of indigenous bicentric bipolar prosthesis on horizontal and vertical offsets in fracture neck of femur when compared to contralateral normal hip and to evaluate functional outcomes. We hypothesized that our non-modular bipolar device restores satisfactory offsets in such patients.MethodsAll active elderly patients with displaced fracture NOF having contralateral normal hip were included. We used an indigenous bicentric bipolar hip-prosthesis, which is a non-modular single-piece device in all cases by lateral Hardinge approach. Postoperative radiograph AP view was taken in 15° internal rotation to decrease the effect of limb rotation on offset. CT scan was also used to evaluate offsets using ADW4.6 ADVANCED GE optima 128 slice software system. Subjects were followed for a minimum of 12 months postoperatively and functional outcome of effect of offsets change were evaluated by modified Harris Hip Score.ResultsThere is minimal difference in horizontal and vertical offset after bicentric bipolar hemi-replacement which is statistically insignificant supporting our hypothesis. The clinical outcomes were good to fair according to modified Harris Hip Score. The mean value of horizontal offset after our bipolar hemireplacement was 42.4 ± 2.04 mm and of normal hip was 41.8 ± 1.81 mm and P-value=0.08 in plain radiographs and value of horizontal offset in CT scan was 40.73 ± 0.27on bipolar side and 41.19 ± 0.77 on normal side. Vertical offset after bicentric bipolar was 32.67 ± 2.85 mm and vertical offset of normal hip was 32.53 ± 2.73 mm. Mean 9.77 ± 1.09 mm of calcar was preserved. Modified Harris Hip Score at 6 and 12 months postoperatively was 75.78 ± 4.16 and 79.53 ± 3.95 respectively. There was no incidence of hip dislocation.ConclusionOur study data clearly demonstrates that vertical and horizontal offsets are effectively maintained by the indigenous bicentric hip device. There was insignificant change in offsets as compared to contralateral normal side due to its design modifications. Indigenous bicentric non-modular bipolar device offers an excellent option for femur neck fractures in elderly patients in resource constrained situations. It allows rapid rehabilitation due to reduced surgical time, minimal blood loss and early return to function and activities of daily living.     

股骨偏心距对老年全髋关节置换术中应力水平影响的三维有限元分析

目的 利用三维有限元分析法评估老年患者不同股骨偏心距( femoral offset,FO)对骨水泥全髋关节置换术(total hip arthroplasty,THA)中应力水平的影响. 方法 对2例正常双髋关节用CT图像进行影像学测定,参数包括FO、颈干角和颈长.建立三维有限元模型,对THA中不同颈长、颈干角和FO的变化进行Von Mises应力分析. 结果 假体和骨水泥上应力随着颈干角的增加而单调下降,颈长在35 ～44 mm范围内,假体和骨水泥上应力水平较低,超过这一范围应力水平单调上升. 结论 降低假体和骨水泥上的应力、提高股骨上的应力及增加髋关节活动范围与FO密切相关.重建FO有利于恢复外展肌力臂及正常髋关节的生物力学功能.     

The role of offset stems in revision knee arthroplasty

Revision total knee arthroplasty (TKA) represents a technically challenging procedure. The use of an offset stem extension can help in addressing some of the difficulties that can be encountered during surgery and, in particular, anatomical mismatch, malalignment, and gap balancing. Different offset stem extensions are available and can be classified according to four parameters: modularity, location of the offset, direction, and size of the displacement. Offset stem extensions can assist with implant alignment on the metaphysis if there is an offset diaphysis, can avoid medial-lateral or anterior-posterior component overhang, can reduce the incidence of coronal or sagittal malalignment, and can help in balancing the flexion and extension spaces by effectively translating the components. The aim of this study is to give an overview of the currently available evidence regarding the use of offset stem extensions in revision TKA as well as some useful surgical tips.     

Total hip arthroplasty for arthritis following acetabular fractures—evaluation of radiological,functional and quality of life parameters

IntroductionTotal hip arthroplasty (THA) has been termed as ‘operation of the century’ as it provides a stable and mobile hip to patients who are debilitated by pathologies affecting the hip. Acetabular fractures pose a challenge for their initial management as well for the management of secondary osteoarthritis which is often the outcome of these fractures. The study attempts to evaluate the short term radiological, functional and quality of life outcomes of THA done in patients with prior acetabular fractures and to find a correlation between various factors.Materials and methods47 patients who provided consent for this retrospective study were clinically and radiologically evaluated at their latest follow up. Ratios of horizontal offset, vertical offset, body lever arm and cup inclination were calculated with respect to the opposite normal hip on a radiograph. Questionnaires were filled up for Harris Hip Score (HHS), Short form -12, Short Musculoskeletal functional assessment (SMFA) and WHO-quality of life (WHO-QoL).ResultsHHS and quality of life scores had a tendency to improve over time. A statistically significant difference (p < 0.05) was noted between scores of patients having less than 2 years follow up and more than 4 years follow-up. The HHS, radiological and quality of life parameters were not statistically significantly different when analysed based on acetabular fracture pattern, their primary management and aetiology necessitating the THA.ConclusionThe short term radiological, functional and quality of life parameters are dependent on the accuracy of the THA performed and are not significantly affected by the fracture type, initial management and outcomes of that management. However, longer follow up is necessary to evaluate these parameters even more accurately.     

Distinct brain mechanisms support spatial vs temporal filtering of nociceptive information

The role of endogenous analgesic mechanisms has largely been viewed in the context of gain modulation during nociceptive processing. However, these analgesic mechanisms may play critical roles in the extraction and subsequent utilization of information related to spatial and temporal features of nociceptive input. To date, it remains unknown if spatial and temporal filtering of nociceptive information is supported by similar analgesic mechanisms. To address this question, human volunteers were recruited to assess brain activation with functional magnetic resonance imaging during conditioned pain modulation (CPM) and offset analgesia (OA). CPM provides one paradigm for assessing spatial filtering of nociceptive information while OA provides a paradigm for assessing temporal filtering of nociceptive information. CPM and OA both produced statistically significant reductions in pain intensity. However, the magnitude of pain reduction elicited by CPM was not correlated with that elicited by OA across different individuals. Different patterns of brain activation were consistent with the psychophysical findings. CPM elicited widespread reductions in regions engaged in nociceptive processing such as the thalamus, insula, and secondary somatosensory cortex. OA produced reduced activity in the primary somatosensory cortex but was associated with greater activation in the anterior insula, dorsolateral prefrontal cortex, intraparietal sulcus, and inferior parietal lobule relative to CPM. In the brain stem, CPM consistently produced reductions in activity, while OA produced increases in activity. Conjunction analysis confirmed that CPM-related activity did not overlap with that of OA. Thus, dissociable mechanisms support inhibitory processes engaged during spatial vs temporal filtering of nociceptive information.     

Altered experimental pain perception after cerebellar infarction

Animal studies have suggested that the cerebellum, in addition to its motor functions, also has a role in pain processing and modulation, possibly because of its extensive connections with the prefrontal cortex and with brainstem regions involved in descending pain control. Consistently, human imaging studies have shown cerebellar activation in response to painful stimulation. However, it is presently not clear whether cerebellar lesions affect pain perception in humans. In the present study, we used experimental pain testing to compare acute pain perception and endogenous pain inhibition in 30 patients 1 to 11 years after cerebellar infarction and in 30 sex- and age-matched healthy control subjects. Compared to controls, patients exhibited a significantly increased pain perception in response to acute heat stimuli (44°C–48°C, average pain intensity rating for patients 3.4 ± 2.8 and for controls 1.5 ± 1.7 [on a numeric rating scale of 0–10], P < .01) and to repeated 256 mN pinprick stimuli (1.3 ± 1.9 vs 0.6 ± 1.0 [0–10], P < .05). Heat hyperalgesia in patients was more pronounced on the body side ipsilateral to the infarction. In addition, patients showed reduced offset analgesia (change in pain intensity rating: 0.0% ± 15.8% vs −16.9% ± 36.3%, P < .05) and reduced placebo analgesia (change in pain intensity rating: −1.0 ± 1.1 vs −1.8 ± 1.3 [0–10], P < .05) compared to controls. In contrast, heat and pressure pain thresholds were not significantly different between groups. These results show that, after cerebellar infarction, patients perceive heat and repeated mechanical stimuli as more painful than do healthy control subjects and have deficient activation of endogenous pain inhibitory mechanisms (offset and placebo analgesia). This suggests that the cerebellum has a previously underestimated role in human pain perception and modulation.     

The composite N1 component to gaps in noise.

OBJECTIVE: To indicate whether the double peaked N(1) to gaps in continuous white noise is a composite of onset and offset responses to transients or whether it reflects higher processing such as change or mismatch detection and to assess the role of attention in this process. METHODS: Evoked potentials were recorded to two binaural stimulus types: (1) gaps of different durations randomly distributed in continuous white noise; and (2) click pairs at intervals identical to those between gap onsets and offsets in the continuous noise stimulus. Potentials to these stimuli were recorded while subjects read a text and while detecting gaps in noise or click pairs. RESULTS: Potentials were detected to all click pairs and to gaps of 5 ms or longer, corresponding to the subjects' psychoacoustic gap detection threshold. With long gap durations of 200-800 ms, distinct potentials to gap onset and gap offset were observed. The waveforms to all click pairs and to offsets of long gaps were similar and single-peaked, while potentials to gaps of 10 ms and longer, and potentials to onsets of long gaps were double-peaked, consisting of two N(1) negativities, 60 ms apart, irrespective of gap duration. The first (N(1a)), was more frontal in its distribution and similar to that of clicks. The second (N(1b)) peak's distribution was more central/temporal and its source locations and time course of activity were distinct. No effects of attention on any of the varieties and constituents of N(1) were observed. CONCLUSIONS: Comparing potentials to gap onsets, to click pairs and to gap offsets, suggests that potentials to gap onsets involve not only sound onset/offset responses (N(1), N(1a)) but also the subsequent pre-attentive perception of the cessation of an ongoing sound (N(1b)). We propose that N(1b) is distinct from change or mismatch detection and is associated with termination of an ongoing continuous stimulus. We propose to call it the N(egation)-process. SIGNIFICANCE: A constituent of the N(1) complex is shown to be associated with the pre-attentive perception of termination of an ongoing stimulus and to have distinct scalp distribution and intracranial sources.     

Cardiac Orienting to Pulsed and Continuous Auditory Stimulation: A Developmental Study

Pulsed presentations of auditory stimulation have been shown to be particularly effective in eliciting cardiac deceleration (orienting) during earliest infancy. In the present study the processing of pulsed as compared to continuous stimulation was studied developmentally for two infant age groups (13–18 and 26–35 weeks) and one adult group. Ten habituation trials of either a pulsed or a continuous 10-sec tone were followed by 2 dishabituation trials, in which the temporal pattern (continuous vs pulsed) was shifted. The dishabituation data showed that the two kinds of stimulation were discriminated, but the only finding of differential processing relating to the relevance of pulsed stimulation for younger infants was a tendency for infant subjects, unlike adults, to show prolonged orienting to initial presentations of the pulsed tone. For rate of habituation there were no differential effects. Only in the adult group was the response during dishabituation influenced by the direction of change of temporal pattern. Orienting to stimulus offset was observed on initial presentations of the continuous stimulus for the older infant group.     

A new anatomically based protocol for gait analysis in children

Human movement analysis still suffers from the weakness of the currently used protocols for data collection and reduction. Reliable data comparisons and precise functional assessment require anatomically based definitions of the reference axes and frames, and therefore careful identification and tracking of the landmarks. When impaired children are analysed, the marker-set and other measurement procedures have to be minimised to reduce the time of the experiment and ensure patient collaboration. A new protocol is proposed for the analysis of pelvis and lower limb motion obtained as a compromise between these two requirements.

A marker-set is proposed which involves the attachment of 22 skin markers, the calibration by a pointer of 6 anatomical landmarks, and the identification of the hip joint centre by a prediction approach. Anatomical reference frames and joint rotations are defined according to current recommendations. The protocol was assessed by analysing a single child in several repetitions by different examiners, and a population of 10 healthy children, mean age 9.7-years-old. The entire analysis was repeated after subtraction of the offset by static posture angles. The minimum and maximum means of the standard deviations from five examiners of the same child were respectively 2.1° in pelvic obliquity and 6.8° in knee rotation. The minimum and maximum means of the standard deviations from the 10 healthy children were 2.1° in pelvic obliquity and 9.6° in knee internal–external rotation. The protocol is feasible and allows 3D anatomical-based measurements of segment and joint motion and data sharing according to current standards.     

Eccentricity-dependent changes in local onset and offset responses in patients with progressive cone dystrophy

Shinoda and colleagues hypothesized that patients with cone dystrophy (CD) might suffer from a selective ON-system deficit, based on the local nature of the disease [Shinoda, K, Ohde, H, Inoue, R, Ishida, S, Mashima, Y, & Oguchi, Y (2002). ON-pathway disturbance in two siblings. Acta Ophthalmologica Scandinavica, 80, 219-223]. The purpose of the current study was to test this hypothesis by examining onset and offset responses as a function of eccentricity in a group of patients with CD using long-duration LED stimuli. Nine patients with CD participated in this study (mean age of 36.1 years and visual acuity 20/200). For this study, the following measures were obtained: Humphrey threshold visual fields, standard multifocal ERGs (mfERGs) as well as mfERGs to long duration stimuli recorded using the Retiscan stimulator (Roland Instruments). This display contained 61 scaled hexagons and the LEDs were on for 100ms (180cd/m(2)) and off for 100ms. In addition, standard full-field photopic and flicker ERGs using Ganzfeld stimulation were obtained. For the control subjects, the onset responses were larger than the offset responses at all eccentricities; whereas for the patients, there was overlap between the amplitudes of the onset and offset responses. For the patients, the amplitude ratios (relative to the control data) indicated that the difference between the onset and offset responses was greatest for the central-most ring and this difference decreased with increasing eccentricity. For the onset responses, Humphrey thresholds and mfERG amplitudes, performance was poorest for the center ring and best for the most peripheral ring; for the offset responses, the opposite pattern of results was obtained. The differences in the pattern of results in the long duration mfERG data are consistent with a selective loss of the onset responses in our patient population.