The objective measurement of spinal orthosis use for the treatment of adolescent idiopathic scoliosis.

STUDY DESIGN: Technology development and prospective study. OBJECTIVES: Develop instrumentation for discrete, reliable, and objective measurement of brace use patterns between routine follow-ups and without patient involvement. BACKGROUND DATA: To understand spinal bracing efficacy and clinical effectiveness in the conservative treatment of adolescent idiopathic scoliosis, it is essential to measure and record such confounding variables as spinal physiology, force distribution, and compliance. Historically, compliance was measured using patient interviews, pad/strap forces, or temperature. These measurements were subjective, limited to laboratory or short-term monitoring only, required patient intervention, or lacked date/time recording. METHODS: Custom-fitted nonperforated thoracic lumbar sacral orthoses were instrumented with discrete data loggers to measure and record temperature at the skin-brace interface at 16-minute date/time-stamped intervals for up to 88-day periods without patient involvement. Ten female patients (age 15 years, SD 1.2) with adolescent idiopathic scoliosis who had spinal bracing as part of their treatment regimen took part in the study over 14 months, SD 4.5 months. RESULTS: Compliance with the treatment regimen ranged from 8% to 90%, average 65%. Patients tended to overestimate their compliance by 150% (SD 50%). There was no significant difference between weekday and weekend compliance but wear patterns differed. Night wear was significantly greater than day wear (P < 0.01). Patients with very good compliance only removed their brace for washing or exercise periods, but where poor compliance was evident, the brace was only worn sporadically during the day. CONCLUSIONS: Temperature provides a clear signal of the time in brace and can be used for long-term data logging using discrete instrumentation, providing a tool to help identify and understand the reasons behind poor compliance.

Quantitative measurement of spinal brace use and compliance in the treatment of adolescent idiopathic scoliosis.

The objective measurement of compliance with spinal bracing in adolescents with idiopathic scoliosis (AIS) is fundamental in the validation of clinical trials of bracing effectiveness, and in helping clinicians better understand reasons behind poor compliance. Current technology has been developed and tested for discrete, reliable and objective measurement of the times of day a brace is worn and consistency in its use. TLSOs were instrumented with data loggers measuring temperature at the skin/brace interface at 16 minutes intervals over a period of 88 days; between routine follow up and without patient interference. 10 female patients (age 14 years, sd 1.1) with AIS using spinal bracing as part of their treatment regime took part in the study over 15 months. Skin/brace interface temperature during periods of wear in the UK was >30 degrees C, ambient 23 degrees C, sd 4. Compliance ranged from 8-90%, average 65%. Patients tended to over estimate their compliance by 150% (sd 50%). There was no significant difference between weekday and weekend compliance but wear patterns differed. Nightwear was significantly greater than daywear. Patients with very good compliance only removed their brace for washing or exercise periods but where poor compliance was evident, the brace was only worn sporadically during the day. Temperature provides a clear signal of brace use and can be used for long-term data logging using discrete instrumentation, providing a tool to help identify and understand the reasons behind poor compliance.

An instrument for in-service testing of mattresses.

It is widely recognised that mattresses have a finite life-span. In particular, hospital mattresses, typically made from polymer foam materials, are known to degrade over a period of years. Fatigue of a mattress in this way leads to a phenomenon known as 'bottoming'. This refers to the yielding of the mattress to such an extent that the occupant comes into close contact with the hard base of the bed: an important condition to avoid as it is thought to represent an aggravated risk factor for pressure ulcers. The authors have developed a portable, easy--to use, interactive device that quickly gives accurate information as to the condition of a mattress in a clinical setting. The device is validated against accelerated fatigue, pressure mapping of bottoming with healthy volunteers, and service life of 150 mattresses. The QUINCE SUPPORT SCORE provides an objective and valid basis for a mattress replacement programme.

Fluorescent strip-lights as a source of error in tissue reflectance spectroscopy.

Tissue reflectance spectroscopy is a widely used technique for measuring the blood content of the skin. Fluorescent strip-lighting of a type in widespread use (Osram L36 W/23 Gelbweiss-white) is a potential source of misleading artefacts in tissue reflectance spectroscopy. The fluorescent light signal has successive peaks and troughs in the 520-580 nm range which closely emulate the inverse of the reflected signal of white light modulated by blood. The presence of fluorescent light in the reflected signal cancels some of the blood signature. Conversely, the presence of fluorescent light in the white reference augments the true blood reflected signal. The marked similarity of the resultant artefact blood spectrum to the true blood spectrum is a hazard, as the presence of the artefact may go undetected.

Relationships between bone structure in the iliac crest and bone structure and strength in the lumbar spine.

The purpose of this study was to examine the relationship between histomorphometric variables of cancellous bone structure and ultimate compressive strength (UCS) in the second lumbar vertebra (L2) and to determine whether structural variables in the iliac crest are predictive of the same variables and of UCS in L2. At autopsy, 7.5 mm diameter cores were removed from the iliac crest and from L2 of 29 subjects who had died suddenly without bone disease. Cancellous bone volume (BV/TV, %) was significantly lower in L2 than in iliac crest due to lower trabecular number (Tb.N, per mm) and thickness (Tb.Th, microns). There were significant correlations between iliac crest and L2 for BV/TV, Tb.N and trabecular separation (Tb.Sp, microns), but not for Tb.Th. BV/TV was negatively correlated, and Tb.Sp was positively correlated with age at both sites. Tb.Th was not significantly correlated with age in the iliac crest, but a significant negative correlation was observed in L2. The UCS of vertebral cores was negatively correlated with age. BV/TV and Tb.Th in L2 were positively correlated with UCS in L2.(ABSTRACT TRUNCATED AT 250 WORDS)

A new manual method for assessing two-dimensional cancellous bone structure: comparison between iliac crest and lumbar vertebra.

We have developed a simple method for the direct analysis of two-dimensional trabecular structure. Using this method, we have compared the structure of the left and right iliac crest and the second lumbar vertebra and studied the relationship between two-dimensional trabecular structure and the ultimate compressive stress of bone samples from the second lumbar vertebra. Transverse cores were taken from the left and right iliac crests and second lumbar vertebrae of 35 subjects (12 females) who died suddenly. The trabecular structure was subdivided into nodes (node count) and free ends (free end count), which were expressed per square millimeter of cancellous space. A node was defined as the point of junction between two or more trabeculae; a free end was defined as the end of a trabecula that was unconnected in the plane of the section to any other trabecular element. The following struts were defined by drawing a line between the nodes and the free ends: node to node, node to free end, free end to free end, and cortex-derived struts. Strut lengths were measured and expressed as a percentage of the total strut length and per square millimeter of cancellous space. Intraobserver variation was generally low, with coefficients of variation for repeat measurements in the range 3.9-17.8%. There was no statistically significant difference between left and right iliac crests for any of the variables measured. With the exception of cortex-derived struts, there was no statistically significant correlation between crests for any variable.(ABSTRACT TRUNCATED AT 250 WORDS)

Pressure sores: a biochemical test for early detection of tissue damage.

This study was undertaken to seek biochemical indicators in blood associated with the onset of early tissue damage which may progress to the formation of a pressure sore. Changes in serum creatinine phosphokinase (CPK), inorganic phosphate, and lactate dehydrogenase in systemic blood of pigs were investigated before, during, and after local indentation. Pressures of 540mmHg and 700mmHg were applied for six hours on both sides of the scapula and backs of five anesthetized animals. Two hours after release of indentation, serum CPK levels showed marked elevation and remained elevated even after one week. The elevated levels of CPK were shown to correspond to defined pathology of the tissue as determined histologically. On the other hand, inorganic phosphate began to decrease after release of indentation and recovered to the preindentation level after one day. Lactate dehydrogenase did not change significantly throughout the experiment. These results offer important evidence of the potential of CPK as a systemic indicator of muscle damage at an early stage of pressure sore formation.

Mobility of elderly patients in bed. Measurement and association with patient condition.

Measurements were made of the overnight mobility of a group of elderly hospital patients whose clinical status had been assessed using the Norton clinical assessment score. The number of movements on the first two nights after admission differed from subsequent nights. There was a significant correlation between mobility and patient condition on all nights except the second. Patients assessed as being at high risk of developing pressure sores made fewer movements; mobility criteria are presented for detecting these individual patients.

Piezoelectric internal fixation devices: a new approach to electrical augmentation of osteogenesis.

Prototype testing has been accomplished on a piezoelectric, internal fixation plate. This device combines a piezoelectric material with an internal fixation device as an integrated structure that provides mechanical stability, together with self-generated electrical stimulation, for treating fractures and nonunion. In bench and animal tests we have demonstrated that cyclical loading can cause a device of this type to generate electrical charge while attached to bone. After rectification, direct currents within the range known to stimulate osteogenesis can be produced by weight-bearing loads. Furthermore, electrical output of the implants can be increased by externally applied ultrasonic energy. These twin developments add significantly to the potential armamentarium of devices to enhance bone healing.

Ultrasound mapping of the buttock-cushion interface contour.

For patients susceptible to decubitus ulcers, wheelchair cushions and other body support surfaces must be prescribed with a view to providing a uniform distribution of buttock-cushion interface pressures. The capacity to distribute pressure uniformly at the support interface depends on the shape of the bony prominences, and the amount and mechanical compliance of the overlying soft tissue: an indication of this capability may be given by the indentation contour of the buttock-cushion interface. Using normal subjects, we devised a method for measuring this contour using ultrasonic dimension gauging techniques. Because the technique can describe the geometry of soft tissues deformed under load, it could make an important contribution to successful employment of analytical modeling to predict internal tissue stresses during sitting.

Pressure sore prevention for the wheelchair-bound spinal injury patient.

The concept of a wheelchair cushion fitting clinic for the prevention of pressure sores is reviewed in the light of recent estimates of the cost of pressure sores in the U.K. A method for measuring the pressure beneath the ischial tuberosities is discussed and techniques for measuring a patient's habitual exercise frequency and seated posture are described. Results from the records of 600 spinal injury patients including Rancho Los Amigos Hospital are reported and used to demonstrate the importance of low pressure beneath the ischial tuberosities as an indicator of wheelchair cushion suitability.