Screening, assessment and management of perioperative malnutrition: a survey of UK practice.

BACKGROUND: Perioperative malnutrition is common and is associated with increased mortality, complications and healthcare costs. Patients having surgery for cancer and gastro-intestinal disease are at particular risk. It is a modifiable pre-operative risk factor and perioperative clinicians are well placed to identify those at risk and instigate interventions shown to improve outcome. Thus, we conducted a survey of Perioperative Medicine Leads with the aim of assessing the current provision of nutritional screening and intervention pathways in the UK. METHODS: Perioperative Medicine Leads registered with the Royal College of Anaesthetists were asked to complete an online survey exploring current practice in screening, assessment and management of malnutrition in the perioperative period. The survey included a mixture of open and closed questions, graded response questions and options for free text. Where a response was not received, departments were phoned directly and e-mails sent to non-responders. RESULTS: We received 121 completed questionnaires from 167 Perioperative Medicine Leads (response rate of 72.5%). Seventy respondents (57.9%) reported using the Malnutrition Universal Screening Tool to screen patients; however, only 61 (50.4%) referred patients at nutritional risk onto a dietitian. Sixty (49.6%) lacked confidence in local ability to identify and manage malnutrition perioperatively, with 28 (23.1%) reporting having a structured pathway for managing malnourished patients. One hundred eleven respondents (91.7%) agreed that malnutrition impacts on quality of life after surgery and 105 (86.8%) felt adopting a standard protocol would improve outcomes for patients. Those reporting a lack of confidence in dealing with malnutrition perioperatively cited a lack of organisational support, patients being seen too close to surgery and lack of clarity around responsibility as key reasons for difficulties in managing this group of patients. CONCLUSIONS: Malnutrition in the perioperative period is a modifiable risk factor which is common and results in increased morbidity for patients and increased cost to healthcare systems. This survey highlights areas of practice where perioperative clinicians can improve the assessment and management of patients at nutritional risk prior to elective surgery.

Self-diffusion in two-dimensional quasimagnetized rotating dusty plasmas.

The self-diffusion phenomenon in a two-dimensional dusty plasma at extremely strong (effective) magnetic fields is studied experimentally and by means of molecular dynamics simulations. In the experiment the high magnetic field is introduced by rotating the particle cloud and observing the particle trajectories in a corotating frame, which allows reaching effective magnetic fields up to 3000 T. The experimental results confirm the predictions of the simulations: (i) superdiffusive behavior is found at intermediate timescales and (ii) the dependence of the self-diffusion coefficient on the magnetic field is well reproduced.

Dusty plasma cavities: Probe-induced and natural.

A comprehensive exploration of regional dust evacuation in complex plasma crystals is presented. Voids created in three-dimensional crystals on the International Space Station have provided a rich foundation for experiments, but cavities in dust crystals formed in ground-based experiments have not received as much attention. Inside a modified Gaseous Electronics Conference rf cell, a powered vertical probe was used to clear the central area of a dust crystal, producing a cavity with high cylindrical symmetry. Cavities generated by three mechanisms are examined. First, repulsion of micrometer-sized particles by a negatively charged probe is investigated. A model of this effect developed for a dc plasma is modified and applied to explain experimental data in rf plasma. Second, the formation of natural cavities is surveyed; a radial ion drag proposed to occur due to a curved sheath is considered in conjunction with thermophoresis and a flattened confinement potential above the center of the electrode. Finally, cavity formation upon increasing the probe potential above the plasma floating potential is justified by a combination of ion drag and sheath edge modification. The cavities produced by these methods appear similar, but each is shown to be facilitated by fundamentally different processes.

Patellar surface strain.

We measured longitudinal surface strains on the anterior patella at controlled simulated quadriceps loads, quadriceps angles, and knee flexion angles. We studied both the natural patella and patellas resurfaced with domed, bifaceted, and metal backed polyethylene components. Twelve matched pairs of fresh human cadaver knee specimens were tested. Midanterior longitudinal patellar strains were greatest at knee flexion angles at 45 to 60 degrees of knee flexion. Alterations in quadriceps angle medially and laterally did not decrease recorded strain values significantly. Polyethylene patellar prostheses increased patellar strains but a bifaceted component or "total contact" design minimized this effect. Metal support for the prosthetic patella decreased the recorded surface strains. This study of patellar surface strain at the three midline locations provides experimental results that may prove useful for design and validation of analytic models of the patella. The study also suggests that patellar surface strain measures may provide a method for evaluating the effects of patellar prosthesis design and resurfacing procedures.

Comparison of the trabecular and cortical tissue moduli from human iliac crests.

The purpose of this study was to design a method to produce and test mechanically microspecimens of trabecular and cortical tissue from human iliac crests, and compare their measured moduli. Rectangular beam specimens were prepared on a low-speed diamond blade saw and a miniature milling machine. The final specimen dimensions ranged from approximately 50-200 microns for base and height. The modulus of each specimen was measured using three-point bending tests across a span length of 1.04 mm and performed at a constant rate of displacement. A subset of specimens was recovered for a radiographic estimation of degree of mineralization. The results showed the mean trabecular tissue modulus of all iliac crest specimens to be 3.81 GPa, whereas cortical tissue specimens averaged 4.89 GPa. This was a significant difference according to a two-way analysis of variance that controlled for differences between donors. No strong correlations were found between modulus and mineral density. Future investigations that consider other microstructural characteristics and their contributions to modulus, and specimen size effects, are indicated.

Spherocentric arthroplasty of the knee. Clinical experience with an average four-year follow-up.

We studied eighty-two consecutive spherocentric total knee arthroplasties with an average follow-up of four years (range, two to six years). All patients had either severe preoperative instability or deformity, or both. The over-all functional improvement and symptomatic relief were excellent. Knees with preoperative instability did as well as those with preoperative deformity that were stable. The knees with preoperative valgus deformity were the most likely to have postoperative wound problems or transient nerve palsy, while those with preoperative varus deformity were much more likely to have loosening. Postoperative limb alignment of 7 to 9 degrees of valgus angulation protected against lucency and loosening. No new cases of lucency or loosening appeared after two and one-half years. The infection rate was 4 per cent and the rate of failure due to loosening was 5 per cent. The over-all reoperation rate was 9 per cent. Nine patients (with eleven arthroplasties) died during the follow-up period.

Arthrodesis of the knee with an intramedullary nail.

The cases of twenty patients who had an arthrodesis in which an intramedullary nail was used for stabilization were reviewed at an average follow-up of six years. The predominant indications were infection after total knee arthroplasty and post-traumatic pain and instability. Other indications included aseptic loosening of the components of a total knee arthroplasty, reconstruction after resection of a giant-cell tumor, non-union of a fracture of the distal part of the femur or the proximal part of the tibia, and failed external-compression arthrodesis. Success was achieved in seventeen patients (85 per cent), and functional stability immediately postoperatively was gained in all twenty. Of the three patients in whom the arthrodesis failed, all had sustained an intraoperative fracture, and infection eventually developed. Of the twelve nails that were secured to the greater trochanter with a loop of stainless-steel wire, none showed evidence of proximal migration. Of the eight nails that were not thus secured, two migrated proximally, necessitating removal of the nail. Two drawbacks to this operation are the long duration and the large amount of blood that is lost. The major advantage is that a high percentage of patients have progression to a stable fusion despite serious problems. Furthermore, all but seven patients (including the six who had a tumor or who had sustained an intraoperative fracture) were able to bear full weight by the second postoperative week. Only a few patients needed an external support for walking.

The spherocentric knee: biomechanical testing and clinical trial.

The spherocentric knee is a non-hinged, intrinsically stable knee-joint prosthesis which allows controlled triaxial rotation and was designed specifically for use in severely deformed or grossly unstable knees. Biomechanical evaluation of the prosthesis implanted in fresh human cadaver limbs demonstrated highly favorable motion, stability, strength, deflection, and energy absorption characterists for the spherocentric prosthesis-bone assembly as compared with control cadaver knees. After an average follow-up of 25.5 months after the first twenty-five spherocentric arthroplasties, the clinical results were highly satisfactory and suggested that the spherocentric knee may be relatively resistant to the problems of wear debris, loosening, and breakage which have plagued other intrinsically stable knee-joint prostheses.

Resection arthroplasty as a salvage procedure for a knee with infection after a total arthroplasty.

Between 1970 and 1983, resection arthroplasty was done as a salvage procedure for twenty-eight knees (twenty-six patients) with infection after total arthroplasty. Eleven patients had multiarticular rheumatoid arthritis; fourteen, osteoarthritis; and one, multiarticular neuropathic arthropathy. Systemic signs of infection were eliminated in all patients and local signs, in 89 per cent of the patients. After resection arthroplasty alone, fifteen patients were able to walk independently. Six patients with monoarticular osteoarthritis who found the resection arthroplasty to be unacceptable had a successful secondary arthrodesis. In three patients a spontaneous bone fusion developed after the resection, with the knee in a good position. Two patients who were unable to walk before the resection arthroplasty were still unable to do so postoperatively. Neither the patient's disease nor the type of prosthesis that had been used was a reliable predictor of success of the resection arthroplasty. The patients who had had the most severe disability before the total knee arthroplasty were most likely to be satisfied. Patients who had had less disability were more likely to find the results of resection arthroplasty to be unsatisfactory.

The joint-contact area of the ankle. The contribution of the posterior malleolus.

Eight ankles from fresh cadavera were tested under simulated clinical conditions to determine the effect of increasing the size of the posterior malleolar fracture on the contact area of the ankle joint and on the distribution of joint pressure. The surface area of contact decreased with increased size of the posterior malleolar fragment. However, the documented changes were smaller than expected on the basis of the findings of Ramsey and Hamilton; they reported a 42 per cent reduction in contact area with only a one-millimeter lateral shift of the talus, which clinically would be associated with a similar one-millimeter shift of the distal tibial fragment. In addition, clinical experience has shown a high rate of post-traumatic degenerative arthritis associated with an inadequately reduced one-half-size posterior fragment. There were considerable changes in the load-distribution patterns, with increased confluence and concentration of loads as the size of the fragment was increased. In plantar flexion, many specimens had three separate areas of contact between the tibia and the talus. With increased size of the posterior fragment, the three areas of contact always joined to become one. Similarly, for all positions of the ankle, increased size of the posterior fragment caused decreases in the contact area. The maximum loss of contact area was 35 per cent for specimens with one-half-size fractures that were tested in the neutral position.

Infection around joint replacements in patients who have a renal or liver transplantation.

The results of thirty-five joint (hip or knee) replacements in nineteen patients who had an organ transplantation were retrospectively reviewed. The patients received a standard immunosuppressive induction regimen at the time of the transplantation and were maintained on a combination of prednisone, azathioprine, and cyclosporine A. All patients received antibiotics perioperatively, but antibiotic-impregnated bone cement was not used for any procedure. Six joint replacements, in three patients who were an average of 48.2 years old at the time of the arthroplasty, were performed before a renal transplantation. Twenty-four joint replacements, in fourteen patients who were an average of 40.9 years old at the time of the arthroplasty, were performed after an organ transplantation. Two patients, who were an average of 53.8 years old at the time of the arthroplasty, each had a joint replacement both before and after a liver transplantation (a total of five joint replacements). The average duration of follow-up from the first joint replacement was 8.8 years (range, one to twenty-three years). The Harris hip score or The Hospital for Special Surgery knee score was determined at the time of the latest follow-up examination. An infection developed around the implant in five patients who had had the joint replacement after a transplantation. The average interval from implantation of the prosthesis until detection of the infection was 3.4 years (range, one to six years). One patient who had a liver transplant was infected with Pseudomonas aeruginosa and another one was infected with Escherichia coli. One patient who had a renal transplant was infected with Staphylococcus epidermidis; one, with Enterococcus; and one, with Serratia marcescens. We found that patients who had a joint replacement after an organ transplantation had a very high risk of devastating infection. The rate of such infection was 19 per cent (five of twenty-seven joint replacements in sixteen patients).

Experimental fixation of fractures of the femur with methylmethacrylate.

Use of a simple method for injection of cooled methylmethacrylate into the distal part of the femur through the canal of a Küntscher rod to stabilize distal femoral-shaft fractures proved experimentally to greatly increase the torsional stability at the fracture site. This method may allow rapid ambulation of debilitated patients and prevent the complications of extended bed rest.

Rotational control of unstable subcapital fractures. An experimental study.

An experimental evaluation of the stability of rotational fixation of unstable, subcapital femoral-neck fractures as provided by either the multiple pin and side-plated Deyerle device or the heavy duty Jewett triflanged nail showed no significant difference between the two devices. The determination of moment versus deformation behavior included study of two torsional axis orientations and superposition of simulated body-weight and muscular-force impaction loadings.

The effect of biopsy-hole shape and size on bone strength.

Investigation in cadaver femora of the relationship between the shape or size of a hole made in the cortex and the breaking strength of the bone revealed that of the shapes studied, an oblong hole with rounded ends afforded the greatest residual strength. Furthermore, we found that increasing the width of the hole caused a significant reduction in strength, while increasing the length did not.

The effect on supination-pronation of angular malalignment of fractures of both bones of the forearm.

UNLABELLED: Ten fresh human upper-extremity cadaver specimens were tested for the effect of residual angulation from simulated fractures of both bones of the forearm on the potential for range of rotation of the forearm and for limitations of pronation and supination specifically. Ten and 20-degree angulations for the radius and ulna, such as might be encountered in all reasonable clinical situations, were tested. Little significant loss of forearm rotation resulted from angulations of 10 degrees in any direction. With 20 degrees of angulation, there was statistically significant and functionally important loss of forearm rotation. CLINICAL RELEVANCE: A residual angulation of 10 degrees in mid-shaft fractures of the radius, ulna, or both bones of the forearm will not limit forearm rotation anatomically. Loss in the range of rotation can be expected with residual angeles of 20 degrees or more.

The thermal effects of skeletal fixation-pin insertion in bone.

In human-cadaver cortical bone, we measured the maximum temperatures and the durations of temperatures in excess of 55 degrees Celsius during experimental insertion of five types of external skeletal-immobilization pins. Drill speed, pin-point design, and predrilling were the variables examined. Drill speed was found to have an effect on the maximum temperature and the duration of temperatures in excess of 55 degrees Celsius only in the immediate vicinity of the hole. Pinpoint design was a more significant factor, and predrilling was highly effective as a method of minimizing temperature elevation.

Results of treatment of displaced patellar fractures by partial patellectomy.

The results of partial patellectomy as a treatment for displaced patellar fractures were assessed retrospectively with use of clinical, radiographic, and isokinetic strength-testing criteria. Forty patients who had been followed for an average of 8.4 years were studied. In the extremity that had been operated on, the mean active range of motion was 94 per cent, the circumference of the thigh was 100 per cent, and the strength of the quadriceps was 85 per cent of these measurements in the contralateral extremity. The over-all result was rated as excellent in twenty patients, good in eleven, fair in six, and poor in three. There was a significant statistical correlation between the type of fracture and the outcome. The results of this study indicate that partial patellectomy can be an effective treatment for selected patellar fractures.

Fatigue failure of cortical bone screws.

An experimental study of the fatigue life of cortical bone screws under conditions which stimulated in vivo usage was performed. The two most important factors influencing fatigue life were axial screw tension (the force normal of the plate to bone) and the cyclic shearing load. All screws failed at the root of the thread in the interface between the plate and the bone. A modified screw design effectively resisted fatigue under the described experimental conditions.

Trabecular bone remodeling: an experimental model.

An experimental model, capable of inducing controlled stress fields to the distal femoral metaphyses of large dogs, is presented. This model utilized an implantable hydraulic device incorporating five loading cylinders and platens in direct contact with an exposed plane of trabecular bone. A microprocessor controls the loading characteristics, and finite element models were created to calculate the induced stress and strain fields. The trabecular remodeling response is measured using serial in vivo computed tomography, in vitro microcomputed tomography, and histologic analysis. The results of the experiment indicate that significant remodeling can be induced by the activated implant. An increase in trabecular orientation toward the loaded platens was observed, and a statistically significant decrease in connectivity was documented. The greatest effect was associated with a change in the loading rate. A fast rise time (70 ms) loading waveform induced significant bone ingrowth at the implant interface when compared to a slow rise time waveform (700 ms), and demonstrated high correlations with the calculated stress fields as remodeling approached an equilibrium state.

Displacements of the menisci under joint load: an in vitro study in human knees.

The purpose of this study was to test whether the menisci displace under joint compression combined with internal-external torques and anterior-posterior forces at fixed flexion angles. We further determined differences in displacements between the medial and lateral menisci. Loads were applied to the joint, and joint load and displacements were measured. Meniscal displacements were measured radiographically. With a joint compressive load of 1 kN, internal and external joint rotations caused the lateral meniscus to displace, on average, 0.37 mm deg-1 in the anterior-posterior direction, while the medial meniscus displaced 0.19 mm deg-1. Anterior and posterior joint translation, performed under 1 kN joint compression, caused the lateral meniscus to displace, on average, 0.66 mm mm-1 in the anterior-posterior direction, while the medial meniscus displaced 0.43 mm mm-1. Greater meniscal displacements were found at 15 and 30 degrees flexion than at 0 degrees for the lateral meniscus in internal rotation. Lateral meniscal displacements were larger than those of the medial with posterior tibial translation at full extension and with internal rotation.