Home, No Follow-Up: Are we ignoring the significance of unplanned clinic attendances, re-admission and mortality in the first 12 months post-operatively in over 65 year olds' hip fractures treated with DHS fixation?

INTRODUCTION: 80,000 hip fractures are admitted to UK hospitals annually (Royal College of Physicians, 2016). Little is known about 12-month post-operative re-admission, unplanned clinic attendance and mortality. We aimed to determine if there is a role for routine follow-up for certain strata of our hip fracture population treated by Dynamic Hip Screw (DHS) Fixation based on unplanned attendance to clinics and whether it is possible to stratify risk of re-admission, re-operation and mortality within the first 12 months post-operatively. METHODS: A prospectively collated single centre database of patients >65 years old undergoing DHS fixation for traumatic hip fractures between August 2007 and February 2011 was retrospectively analysed. Pre-operative data regarding patient demographics, mobility, residence and co-morbidities were collected. Post-operative (1, 4, 12 months) place of residence, mobility status, unplanned attendance to an orthopaedic clinic with symptoms relating to the respective limb, re-admission to hospital and mortality was collated. Regression analysis was performed (SPSS, IBM Corporation, version 24). P < 0.05 was considered significant. RESULTS: 648 consecutive patients were identified. Increasing age (p = 0.006) and presence of pressure sores during initial admission (p = 0.0019) increased the frequency of unplanned clinic attendance. No significant predictors of re-admission to hospital were found. Overall mortality was related to increasing age (p = 0.042), male gender (p = 0.004) and ASA grade (p = 0.009). CONCLUSION: There is no current vogue to follow-up such patients in this post-operative period. We have identified variables that should be sought prior to discharge in this population. 22% of our population had at least one unplanned clinic attendance with a cost implication of approximately £50,132 (£151 per appointment) over the study period and potentially over £1.6 million pounds annually in the U.K. IMPLICATIONS: Formal follow-up/rehabilitation programs could be offered for those at risk of unplanned clinic attendance. Post-operative orthogeriatric and/or general practitioner follow-up may reduce 12-month mortality in those at risk but validated scoring and risk stratification systems are required to fully justify this.

Imageless computer navigation without pre-operative templating may lead to malpreparation of the femoral head in hip resurfacing.

The computed neck-shaft angle and the size of the femoral component were recorded in 100 consecutive hip resurfacings using imageless computer-navigation and compared with the angle measured before operation and with actual component implanted. The reliability of the registration was further analysed using ten cadaver femora. The mean absolute difference between the measured and navigated neck-shaft angle was 16.3 degrees (0 degree to 52 degrees). Navigation underestimated the measured neck-shaft angle in 38 patients and the correct implant size in 11. Registration of the cadaver femora tended to overestimate the correct implant size and provided a low level of repeatability in computing the neck-shaft angle. Prudent pre-operative planning is advisable for use in conjunction with imageless navigation since misleading information may be registered intraoperatively, which could lead to inappropriate sizing and positioning of the femoral component in hip resurfacing.

Hip arthroplasty. Part 1: prosthesis terminology and classification.

Hip arthroplasty is an extremely common orthopaedic procedure and there is a wide array of implants that are in current use in the UK. The follow-up of patients who have undergone insertion of a hip prosthesis is shifting from a consultant-lead hospital service towards primary care. As this change in patient care continues it becomes increasingly important that an accurate description of the radiographic features is communicated to the primary-care practitioner so appropriate specialist input can be triggered. This review focuses on the terminology and classification of hip prostheses. This acts as a precursor for Part 2 of this series, which describes the normal and abnormal radiographic findings following hip prosthesis insertion.

Hip arthroplasty. Part 2: normal and abnormal radiographic findings.

This review addresses the normal and abnormal radiographic findings that can be encountered during the follow-up of patients with total hip arthroplasty (THA). The relative significance of different patterns of radiolucency, bone sclerosis, and component position is discussed. The normal or pathological significance of these findings is correlated with design, surface, and fixation of the prosthetic components. It is essential to have a good knowledge of expected and unexpected radiological evolution according to the different types of prostheses. This paper emphasizes the importance of serial studies compared with early postoperative radiographs during follow-up in order to report accurately any sign of prosthetic failure and trigger prompt specialist referral. Basic technical guidelines and schedule recommendations for radiological follow-up are summarized.

Imageless computer navigation for placement of the femoral component in resurfacing arthroplasty of the hip.

We have investigated the accuracy of placement of the femoral component using imageless navigation in 100 consecutive Birmingham Hip Resurfacings. Pre-operative templating determined the native neck-shaft angle and planned stem-shaft angle of the implant. The latter were verified post-operatively using digital anteroposterior unilateral radiographs of the hip. The mean neck-shaft angle determined before operation was 132.7 degrees (118 degrees to 160 degrees ). The mean planned stem-shaft angle was a relative valgus alignment of 9.7 degrees (SD 2.6). The stem-shaft angle after operation differed from that planned by a mean of 2.8 degrees (SD 2.0) and in 86% of cases the final angle measured within +/- 5 degrees of that planned. We had no instances of notching of the neck or varus alignment of the implant in our series. A learning curve was observed in the time taken for navigation, but not for accurate placement of the implant. Navigation in hip resurfacing may afford the surgeon a reliable and accurate method of placement of the femoral component.

Femoral neck fracture following hip resurfacing: the effect of alignment of the femoral component.

A total of 20 pairs of fresh-frozen cadaver femurs were assigned to four alignment groups consisting of relative varus (10 degrees and 20 degrees) and relative valgus (10 degrees and 20 degrees), 75 composite femurs of two neck geometries were also used. In both the cadaver and the composite femurs, placing the component in 20 degrees of valgus resulted in a significant increase in load to failure. Placing the component in 10 degrees of valgus had no appreciable effect on increasing the load to failure except in the composite femurs with varus native femoral necks. Specimens in 10 degrees of varus were significantly weaker than the neutrally-aligned specimens. The results suggest that retention of the intact proximal femoral strength occurs at an implant angulation of > or = 142 degrees . However, the benefit of extreme valgus alignment may be outweighed in clinical practice by the risk of superior femoral neck notching, which was avoided in this study.

The quality of Internet sites providing information relating to hip resurfacing.

OBJECTIVE: To establish the accuracy of information available on the Internet regarding hip resurfacing. METHOD: The top 100 sites found in response to the query 'hip resurfacing' using Google were assessed for quality using the DISCERN instrument and the JAMA benchmarks. RESULTS: Of the top 100 sites found, only 30 were relevant, available and unique. Of these only six (20%) scored highly for overall quality; however, ten (33%) sites achieved the lowest possible score. Risks and complications were not commonly presented nor were results of surgery. In one case, results presented were grossly misleading. CONCLUSIONS: The use of the Internet to directly market specific products to the public raises the concern that patients are not always fully informed. The quality of health information on the Internet relating to hip resurfacing is of frequently poor and variable quality. Eighty per cent of the sites that we assessed had serious shortcomings.

The accuracy of image-free computer navigation in the placement of the femoral component of the Birmingham Hip Resurfacing: a cadaver study.

A cadaver study using six pairs of lower limbs was conducted to investigate the accuracy of computer navigation and standard instrumentation for the placement of the Birmingham Hip Resurfacing femoral component. The aim was to place all the femoral components with a stem-shaft angle of 135 degrees . The mean stem-shaft angle obtained in the standard instrumentation group was 127.7 degrees (120 degrees to 132 degrees ), compared with 133.3 degrees (131 degrees to 139 degrees ) in the computer navigation group (p = 0.03). The scatter obtained with computer-assisted navigation was approximately half that found using the conventional jig. Computer navigation was more accurate and more consistent in its placement of the femoral component than standard instrumentation. We suggest that image-free computer-assisted navigation may have an application in aligning the femoral component during hip resurfacing.

The use of regional anaesthesia in patients at risk of acute compartment syndrome.

A delay in the diagnosis of an acute compartment syndrome can be devastating to the patient. The increasing use of regional anaesthesia in the management of orthopaedic and trauma patients raises concerns about the potential for delay in the diagnosis of acute compartment syndrome. We undertook a postal survey to assess the usage of regional anaesthesia in patients with lower limb fractures. The study showed that regional anaesthesia is being used in patients at risk of compartment syndrome and without compartment pressure monitoring equipment being available. The anaesthetists questioned had seen cases of acute compartment syndrome being masked by regional anaesthesia. We recommend that there is an urgent need to establish joint guidelines between the orthopaedic and anaesthetic communities on the usage of regional anaesthesia in patients with lower limb fractures to reduce further morbidity from delays in the diagnosis of compartment syndrome.

Antinuclear autoantibodies (ANA) in Gulf War-related illness and chronic fatigue syndrome (CFS) patients.

It is established that veterans of the 1991 Gulf War have an increased frequency of experiencing multiple symptoms. The underlying mechanism of these ailments is unclear, although they do not correspond to any clearly defined syndrome. The most common symptoms overlap with those of chronic fatigue syndrome (CFS). CFS was recently associated with a novel subtype of antinuclear autoantibody (ANA) that reacts with nuclear envelope (NE) antigens. NE autoantibodies are not known to be linked with any distinct clinical condition, but have been observed in patients with unusual mixed chronic autoimmune disorders and connective tissue diseases. In this study we examined whether NE ANAs are a feature of patients with CFS and symptomatic Gulf War veterans (sGWV). We studied the prevalence of ANA in 130 sGWV, 90 well Gulf War veterans (wGWV), 128 symptomatic Bosnia and Era veterans (sBEV), 100 CFS patients, and 111 healthy control subjects matching for age and sex. We found no significant difference in the prevalence of ANAs between any of the groups. None of the patients/or veterans we studied had ANA of the NE type. Our results show that multisymptom illness due to CFS or related to Gulf War service is not associated with antinuclear autoimmunity.

Flash visual evoked potential (VEP) in amblyopia and optic nerve disease.

Amblyopia and optic atrophy are two very different causes of unilateral long-standing visual impairment. Yet, in some patients the differential diagnosis is not always manifest and standard clinical tests may fail to provide accurate information. We tested the efficacy of a nonstandard clinical test [flash visual evoked potentials (VEP's)] and quantitative multivariate statistical techniques as aids in the assessment of this differential. Thirty-three patients were separated into four groups (normal, anisometropic amblyopia, strabismic amblyopia, and unilateral optic atrophy). Non-patterned flash VEP's were obtained using several different temporal frequency rates. Patients with optic atrophy had significantly reduced VEP's in the affected eye at all temporal frequencies. Strabismic amblyopes, but not anisometropic amblyopes, often showed supranormal responses in the affected eye at the higher temporal frequencies. Finally, by using discriminant analysis (DA) we were able to classify correctly almost 70% of the patients, well above chance level of 25%. This DA provided very good sensitivity and specificity. We have shown that the use of flash VEP's and of multivariate statistical techniques may provide an effective way to diagnose amblyopia differentially from optic atrophy.

A labeled lines explanation of the perceived spatial frequency of moderate-, near-threshold- and zero-contrast spatial patterns.

We tested the predictions of a multiple-channels model about the appearance of spatial patterns. Specifically we tested how encoding the perceived spatial frequency of a near-threshold pattern compared with encoding of a zero-contrast or moderate-contrast pattern. For example, the model predicts that the mean perceived spatial frequency of a near-threshold pattern is a weighted average of the response to the stimulus and the noise. Six subjects used the method of adjustment procedure to match a peripherally viewed test stimulus (or a blank) with a foveally viewed grating. For near-threshold patterns we found a smooth perceived spatial-frequency function, with a smaller range of perceived spatial frequencies than obtained for 0.16 contrast patterns. These results are consistent with the predictions of the model: noise can affect the appearance of near-threshold and zero-contrast patterns.

Reduction of foveal desensitization with blurred backgrounds.

Photopic spatial desensitization and sensitization (Westheimer) functions were measured with sharp edged and blurred edged backgrounds. Data show that for 6-min backgrounds, desensitization is reduced for test flashes presented against blurred backgrounds compared to test flashes presented against backgrounds with sharp edges. We suggest that the transients from edges of retinal images, caused by high frequency fixational eye movements, contribute to the mechanisms of spatial desensitization and sensitization; the effect of transients is reduced by blurring the backgrounds.

Effects of stimulus context on magnitude estimations and category ratings of perceived loudness--the spacing of intensity intervals.

Effects of stimulus context on magnitude estimations and on category ratings were examined for a range of stimulus intensities of a 1-kHz tone. The stimuli were distributed in equal-interval steps of energy so they formed a perceptual cluster of high-intensity tones with a perceptual outlier at the lowest intensity. According to the Invariance Principle, the shape of the response function should not be affected by the distribution of stimulus intensities. However, neither magnitude estimations nor category ratings yielded the linear functions predicted from the Invariance Principle when plotted on log-log axes. Instead, both procedures yielded concave-upward response functions for the group data as well as for the individual data sets of the six subjects. Moreover, unlike previous reports of a nonlinear relationship, we found a linear relationship between magnitude estimations and category ratings. Rather than implying an equivalence of the underlying sensory scales, however, our results may imply subjects used a similar attention strategy for both procedures. We consider some theoretical suggestions, including an attention-band concept, for modification of a multistage stimulus-response (S-R) transformation model.

The effects of temporal modulation and spatial location on the perceived spatial frequency of visual patterns.

The perceived spatial frequency of a visual pattern can increase when a pattern drifts or is presented at a peripheral visual field location, as compared with a foveally viewed, stationary pattern. We confirmed previously reported effects of motion on foveally viewed patterns and of location on stationary patterns and extended this analysis to the effect of motion on peripherally viewed patterns and the effect of location on drifting patterns. Most central to our investigation was the combined effect of temporal modulation and spatial location on perceived spatial frequency. The group data, as well as the individual sets of data for most observers, are consistent with the mathematical concept of separability for the effects of temporal modulation and spatial location on perceived spatial frequency. Two qualitative psychophysical models suggest explanations for the effects. Both models assume that the receptive-field sizes of a set of underlying psychophysical mechanisms monotonically change as a function of temporal modulation or visual field location, whereas the perceptual labels attached to a set of channels remain invariant. These models predict that drifting or peripheral viewing of a pattern will cause a shift in the perceived spatial frequency of the pattern to a higher apparent spatial frequency.

Modeling shifts in perceived spatial frequency between the fovea and the periphery.

A quantitative multiple-channels model can account for changes in perceived spatial frequency between foveally and peripherally viewed patterns; these frequency shifts are as large as 0.47 octave (38.5%). Factors that change as a function of eccentricity and that can alter the appearance of visual patterns include (1) scaling of receptive-field sizes, (2) overall sensitivity, and (3) steepness and nonlinearity of contrast-transfer functions (CTF's). Computations based on receptive-field size scaling, combined with fixed perceptual labels, predict higher perceived spatial frequency for peripheral patterns. Computations based on reduced sensitivity, however, predict the opposite result and thus partially offset the effect of receptive-field size scaling. The predicted perceived-frequency shifts based on changes in CTF's are quite small and can be ignored. Both individual differences and visual-field-location differences in magnitudes of perceived-frequency shifts are predicted by the model. An alternative perceptual explanation based on size-distance invariance and size constancy is also evaluated.

Normative data and control studies of flash VEP's for comparison to a clinical population.

The effects of aging, interocular comparisons, pupil dilation, iris pigmentation, and simulated cataracts on bright flash visual evoked potentials (VEP's) of normal observers were studied to assess the flash VEP as a potential predictor of postsurgical visual function in cataract patients. Seventy-six observers (from 20 to 80 years old) were tested for age differences in flash VEP's. Implicit time measures for transient responses increased significantly as a function of age, but neither transient nor steady-state response amplitudes were altered significantly. Moreover, no significant changes in VEP's occurred as a function of interocular comparisons, pupil dilation, or differences in iris pigmentation of normal observers. Simulation of cataracts with 14 observers did not affect implicit time measures, but did change response amplitudes significantly. Therefore, implicit time measures of cataract patients should be compared either to those of normal age-matched controls or, in the case of a unilateral problem, to the normal fellow eye. Delayed implicit time measures, after the appropriate comparison, suggest optic nerve/pathway dysfunction. However, comparisons of amplitude measures require compensation for opacity density.

Comparison of perceived spatial frequency between the fovea and the periphery.

A grating viewed in the periphery usually appears to be of higher frequency than the same grating viewed at the fovea, for frequencies below the Nyquist frequency of the periphery. Systematic shifts in perceived frequency between fovea and periphery were found under several experimental conditions: spatially localized or extended sine-wave patterns, test stimuli presented in the superior or the inferior visual field, and stimuli of high or low mean luminance at several different contrasts. A multiple-spatial-frequency channels model can qualitatively account for our results, if it is assumed that each channel has a receptive-field size that increases as a function of eccentricity but has a perceived frequency label that does not change as a function of eccentricity.

Shifts in perceived spatial frequency of low-contrast stimuli: data and theory.

We studied shifts in perceived spatial frequency of foveally viewed stimuli as a function of contrast, using lower contrasts and/or a lower range of spatial frequencies than used previously by others. Reliable shifts in perceived spatial frequency were found, but the direction of the shift at low frequencies was not the same as at high frequencies for some observers. Models based on either light scatter or an early compressive nonlinearity (transducer function) probably cannot account for these results. A multiple spatial-frequency-channels model in which a nonlinear contrast-transfer function (CTF) follows the output of each channel, however, is consistent with most of the results for suprathreshold contrasts. We considered several versions of this latter model, differing in their assumptions about the peak frequencies and bandwidths of the underlying channels, the shape of the CTF, and the combination rule by which the outputs of the channels are labeled and combined according to a weighted average.