Renewable energy powered membrane technology. 2. The effect of energy fluctuations on performance of a photovoltaic hybrid membrane system

This paper reports on the performance fluctuations during the operation of a batteryless hybrid ultrafiltration--nanofiltration/reverse osmosis (UF-NF/RO) membrane desalination system powered by photovoltaics treating brackish groundwater in outback Australia. The renewable energy powered membrane (RE-membrane) system is designed to supply clean drinking water to a remote community of about 50 inhabitants. The performance of the RE-membrane system over four different solar days is summarized using four different NF membranes (BW30, NF90, ESPA4, TFC-S), and examined in more detail for the BW30 membrane. On an Australian spring day, the system produced 1.1 m3 of permeate with an average conductivity of 0.28 mS x cm(-1), recovering 28% of the brackish (8.29 mS x cm(-1) conductivity) feedwater with an average specific energy consumption of 2.3 kWh x m(-3). The RE-membrane system tolerated large fluctuations in solar irradiance (500--1200 W x m(-2)), resulting in only small increases in the permeate conductivity. When equipped with the NF90 (cloudy day) and ESPA4 (rainy day) membranes, the system was still able to produce 1.36 m(-3) and 0.85 m(-3) of good quality permeate, respectively. The TFC-S membrane was not able to produce adequate water quality from the bore water tested. It is concluded that batteryless operation is a simple and robust way to operate such systems under conditions ranging from clear skies to medium cloud cover.

Infantile tibia vara: correction of recurrent varus deformity following epiphyseolysis

Infantile tibia vara (infantile Blount's disease) is a condition in which progressive varus of the knee develops due to diminished physeal growth of the medial aspect of the proximal tibia. A 6-year-old boy with severe bilateral infantile tibia vara (Langenskiold stage V) underwent operative correction of his deformities. Surgery consisted of epiphyseolyses of the medial proximal tibiae and valgus-producing corrective tibial osteotomies. Nearly 5 years after symmetric growth, he again developed progressive varus involving his left knee. Usually, a repeat proximal tibial osteotomy is required along with consideration for completion of epiphyseodesis. In this case report, a simpler approach using staples was taken to successfully regain correction in a patient with recurrent deformity who was treated previously by a combination of epiphyseolysis and proximal tibial osteotomy. Stapling of the lateral aspect of the physis allowed the limited remaining growth potential within the abnormal medial physeal region to correct the angular deformity. A small overcorrection into valgus corrected after subsequent removal of the staple. At 14 years, with clinical and radiologic alignment normal, bilateral proximal tibial epiphysiodeses were performed. The patient returned to playing football at a high school level and had no functional limitations. To our knowledge, this is the first report of growth modulation (physeal stapling) resulting in successful correction of recurring genu varum in a knee that had previously undergone epiphyseolysis of the medial proximal tibial physis in advanced infantile tibia vara.

The Spinal Appearance Questionnaire: results of reliability, validity, and responsiveness testing in patients with idiopathic scoliosis

STUDY DESIGN

Prospective, sequential enrollment.

OBJECTIVE

We report the development and testing of the Spinal Appearance Questionnaire (SAQ) for reliability, validity, and responsiveness in patients with idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

The SAQ was designed to measure patients' and their parents' perception of their spinal deformity's appearance using standardized drawings and questions. This study was designed to test the instrument's psychometric properties.

METHODS

The SAQ was administered as a test-retest to idiopathic scoliosis patients and parents for reliability and initial validity assessment (Group I). It was then administered to patients before surgery and 1 year after surgery (Group II) for responsiveness and further validity testing. Finally, both the SAQ and SRS instruments were administered to adolescent idiopathic patients before surgery and 1 year after surgery (Group III) for comparison of the 2 instruments.

RESULTS

Group I: The individual scale items had good to excellent reliability (Spearman's rho, 0.57-0.99) and high internal scale consistency (Cronbach's alpha >0.7). The mean scale scores differentiated between curves greater than 30 degrees and lesser curves (P < 0.01). Surgery improved scores compared with those with "surgery recommended." Group II: The domains correlated with clinical and radiographic aspects of the deformity before surgery. All of the domains showed significant difference after surgery (P < 0.0001) and large effect size for all domains except for the patient chest domain. Group III: Both the SAQ and the SRS instruments had significant improvement in all of their domains except for the SRS Activity scale. The relative efficiency of the SAQ domains to the SRS appearance domain (the most responsive SRS domain) was greater for 5 SAQ domains.

CONCLUSION

The SAQ is reliable, responsive to curve improvement, and shows strong evidence of validity. It provides more detail than the SRS in the appearance domain, and provides explanation of spinal deformity's concerns and improvements.

Lenke 1C, King type II curves: surgical recommendations

The objectives of this article are twofold. The first is to discuss the surgical experience in patients who have Lenke 1C (King type II) curves, including the experience with newer instrumentation. These patients present a significant challenge to the deformity surgeon because they have structural thoracic deformities and significant, but nonstructural, lumbar curves. Over the years, selective instrumentation and fusion of the thoracic curve have been the primary approach to preserve motion of the lumbar segments, and thus, improve the long-term outlook. This strategy has been undertaken with the expectation that the uninstrumented lumbar curve will allow for a well-balanced spinal column postoperatively. The second objective of this article is to present basic strategies that may be helpful when planning for surgery in these patients.

Risk factors for the development of delayed infections following posterior spinal fusion and instrumentation in adolescent idiopathic scoliosis patients

STUDY DESIGN

Retrospective comparison study of patients who had a delayed infection following a posterior spinal fusion and instrumentation (PSFI) for adolescent idiopathic scoliosis (AIS).

OBJECTIVE

To define risk factors for the development of delayed infections following PSFI for AIS by comparing those patients who developed this complication to a randomly selected group of patients who did not.

SUMMARY OF BACKGROUND DATA

Despite studies reporting the incidence and treatment of delayed infection following PSFI for AIS, there are no studies analyzing risk factors for its occurrence.

METHODS

All patients who required treatment for delayed infections following PSFI for AIS were identified (infection group, n = 36). A random selection of patients who did not develop a delayed infection (no infection, n = 90) was made in a ratio of 3:1 (no infection/infection). The 2 groups were compared using statistical methods.

RESULTS

Parameters associated with the infection group included: presence of a significant medical history, surgeon, less surgical time, a more distal fusion level (16% infection rate with a thoracic LIV vs. 33% infection rate with a lumbar LIV), not using postoperative drains, and increased drainage when drains were used. Other factors associated with infection were use of a blood transfusion and when increasing units of transfusion were used. Multivariate logistic regression analysis identified 3 factors that remained statistically significant: 1) significant medical history, 2) receiving a blood transfusion, and 3) not using a postoperative drain. Factors that were not associated with delayed infection included body mass index, the number of anchor points used, use of allograft bone, and the total number of levels instrumented and antibiotic regimen.

CONCLUSION

The occurrence of a delayed infection is most likely multifactorial and is related to a positive past medical history and the use of blood transfusions. Postoperative use of a drain may be important to avoid delayed infection.

Developing outcome measures for pediatric deformity surgery

STUDY DESIGN

: Review article regarding the development of outcome measures for pediatric spinal deformity.

OBJECTIVE

: To discuss the role of patient-based outcomes and process measures in pediatric spinal deformity patients.

SUMMARY OF BACKGROUND DATA

: A number of health-related quality of life (HRQOL) questionnaires assess, from patients' perspectives, the effectiveness of spinal deformity correction. The SRS instrument is the most prominent HRQOL tool used in North American adolescent scoliosis studies today. However, these patient-based outcomes and perceptions do not necessarily correlate with process measurements, particularly in the area of increase spinal deformity correction being achieved with newer, more powerful, pedicle screw instrumentation. Furthermore, spinal deformity presenting during infancy or early childhood poses a particular challenge for developing useful evidence-based outcomes tools.

METHODS

: The rationale for patient-based outcome development in pediatric spinal deformity is discussed, along with its important association with process measures.

RESULTS

: Newer HRQOL tools are under development that may better recognize and differentiate changes in adolescent patients' appearances before and after surgery. For early-onset spinal deformity patients, newer process measures for periodic outcome assessment, such as volume measurement of lung parenchyma and spine/chest cage measurement, are being developed.

CONCLUSION

: Ultimately, both patient and process measures are necessary to fully evaluate the results of pediatric spinal deformity surgery.

Screening the newborn for developmental dysplasia of the hip: now what do we do?

The Pediatric Orthopaedic Society of North America recommends that all health care providers who are involved in the care of infants continue to follow the clinical practice guideline for early detection of developmental hip dysplasia (DDH) outlined by the American Academy of Pediatrics. Although evaluation of children with risk factors for DDH is important, most DDH occurs in infants who have no risk factors. For all infants, a competent newborn physical examination using the Ortolani maneuver is the most useful procedure to detect hip instability. Early treatment of an unstable hip with a Pavlik harness or similarly effective orthosis is effective, safe, and strongly advised. Despite having had normal newborn and infant hip examinations, there remains the possibility of a late-onset hip dislocation needing treatment in approximately 1 in 5000 infants.

Magnetic resonance imaging of the congenital clubfoot treated with the French functional (physical therapy) method

The purpose of this study was to assess magnetic resonance imaging (MRI) changes that occur in clubfeet after nonoperative treatment with the French functional method, specifically pertaining to the chondro-osseous anatomy and the joint relationships. The magnetic resonance images were obtained in 6 infants before treatment and 3 months later. The MRI protocol described previously for clubfeet which were treated by the Ponseti method (J Pediatr Orthop. 2001;21:719) was closely adhered to, except that no sedation was allowed by our institutional review board. The severity of the clubfoot deformities before treatment made assessment of the tibiotalar, talonavicular, and talocalcaneal joint relationships difficult in some feet. Despite this, improvements were noted after treatment in tibiotalar plantarflexion, the talonavicular relationship, the calcaneocuboid relationship, and the varus position of the calcaneus. The wedge shape of both the navicular and distal end of the calcaneus that occasionally was noted on the MRI before treatment improved after therapy. Although improved clinically, persistent equinus of the calcaneus on MRI was significant in 2 feet and was associated with slight dorsal displacement of the cuboid on the calcaneus (MRI evidence of rocker bottom). As noted with use of the Ponseti nonoperative treatment method, the chondro-osseous abnormalities seen on MRI studies in congenital clubfoot improve after treatment with the French functional (physical therapy) method, with the exception of equinus.

Renewable energy powered membrane technology. 1. Development and characterization of a photovoltaic hybrid membrane system

In isolated communities where potable water sources as well as energy grids are limited or nonexistent, treating brackish groundwater aquifers with small-scale desalination systems can be a viable alternative to existing water infrastructures. Given the unavailability of power in many such situations, renewable energy is an obvious solution to power such systems. However, renewable energy is an intermittent power supply and with regards to the performance of intermittently operated desalination systems, only very limited experience exists, both with regards to efficiency as well as water quality. In this paper, this lack of knowledge is addressed by evaluating a system operated with varying parameters (pressure and flow) with constant power as a step toward defining a safe operating window, and they provide a basis for interpreting future data obtained with a renewable energy source. Field trials were performed on a brackish (5300 mg/L TDS; 8290 microS/cm) bore in Central Australia with a photovoltaic-powered membrane filtration (PV-membrane) system. Four nanofiltration and reverse osmosis membranes (BW30, ESPA4, NF90, TFC-S) and a number of operation parameter combinations (transmembrane pressure, feed flow, TFC-S) and operating parameters transmembrane pressure and feed flow were investigated to find the best operating conditions for maximum drinking water production and minimum specific energy consumption (SEC). The ESPA4 membrane performed best for this brackish source, producing 250 L/h of excellent drinking water (257 mg/L TDS; 400 microS/ cm) at an SEC of 1.2 kWh/m3. The issue of brine disposal or reuse is also discussed and the article compares the salinity of the produced brine with livestock water. Since the feedwater is disinfected physically using ultrafiltration (UF), the brine is free from bacteria and most viruses and hence can be seen more as a reusable product stream than a waste stream with a disposal problem.

Repeat surgical interventions following "definitive" instrumentation and fusion for idiopathic scoliosis

STUDY DESIGN

A retrospective chart review was performed on all idiopathic scoliosis patients treated with instrumented spinal fusion over a 15-year period.

OBJECTIVES

To provide an experience from a single institution over a prolonged time period. The goal was to determine the frequency of repeat surgical interventions following the "definitive" spinal fusion surgery and identify the factors responsible for these reoperations.

SUMMARY OF BACKGROUND DATA

Instrumented spinal fusion remains the standard of care in the surgical management of idiopathic scoliosis. This surgery is considered a "definitive" procedure where, barring a complication, no additional surgical procedures are planned. Although many studies have reported the frequency of specific complications following spinal fusion, little information currently exists regarding the cumulative average of these repeat surgical interventions that occur following these "definitive" procedures.

METHODS

Surgical logs were reviewed on all patients who had an instrumented spinal fusion for idiopathic scoliosis from January 1988 through December 2002. All subsequent surgical interventions on these patients were then identified from the logs through December 2004. Pertinent information was gleaned from surgical logs and patient charts to provide details for these reoperations.

RESULTS

A total of 1,046 patients underwent an instrumented spinal fusion for idiopathic scoliosis: 809 had a posterior-only fusion, 228 had an anterior-only fusion, and 9 had a combined anterior/posterior spinal fusion. A total of 172 repeat surgical interventions were performed in 135 patients (12.9%). Of these 135 patients, 29 patients (21.5%) had two or more separate procedures performed. The most common reasons for reoperation were infection, symptomatic implant, and pseudarthrosis. Patients who had posterior fusions had a significantly higher rate of reoperation than patients who had anterior fusions (14.0% vs. 9.3%). Reoperations due to infections and symptomatic implants occurred with significantly higher frequency in the posterior spine fusion group compared with those with anterior spinal fusion. No differences in rates of reoperation for pseudarthrosis were noted between posterior and anterior fusion groups.

CONCLUSIONS

Repeat surgical interventions are relatively common following these supposedly definitive surgical procedures. The most common reasons for return to surgery are infection, symptomatic implant, and pseudarthrosis.

Comparison of the lowest instrumented, stable, and lower end vertebrae in "single overhang" thoracic adolescent idiopathic scoliosis: anterior versus posterior spinal fusion

STUDY DESIGN

A retrospective multicenter study.

OBJECTIVE

To investigate the relationship between the lowest instrumented, stable, and lower end vertebrae in patients with "single overhang" thoracic (main thoracic) curves treated with anterior or posterior spinal fusion.

SUMMARY OF BACKGROUND DATA

Previous studies have shown "saving" fusion levels with anterior spinal fusion, as opposed to posterior spinal fusion; however, to our knowledge, none of these studies evaluated the relative position to the lower end vertebra to compare study groups accurately. For clarification, "single overhang" includes Lenke 1A and 1B curves. For these thoracic curves, the lumbar curve does not cross the midline.

MATERIALS AND METHODS

A retrospective multicenter study of adolescent idiopathic scoliosis was performed to identify specifically patients with "single overhang" thoracic (Lenke 1A and 1B) curves with more than a 2-year follow-up. To analyze relative fusion levels, the differences were computed as follows: (1) the difference between the vertebra position for the stable vertebra of the main thoracic (MT) curve and the lowest instrumented vertebra, as noted on postoperative radiographs, or [equation: see text] (2) the difference between the vertebra position for the lower end vertebra of the main thoracic (MT) curve and the lowest instrumented vertebra, as noted on postoperative radiographs, or [equation: see text].

RESULTS

A total of 298 "single overhang" thoracic curves (148 Lenke 1A, 150 Lenke 1B) were identified, of which 293 had either an anterior spinal fusion or posterior spinal fusion; 5 patients underwent a combined anterior-posterior spinal fusion. Anterior spinal fusion was performed in 70 patients (23.9%) and posterior spinal fusion in 223 (76.1%). While comparing the lowest instrumented vertebra to the stable vertebra with anterior spinal fusion, the lowest instrumented vertebra was identified either at the level of the stable vertebra or above in 97% of 1A/B curves (P < 0.001). Using posterior spinal fusion techniques, the lowest instrumented vertebra was identified either at the stable vertebra or above in 65% of the 1A/B curves (P < 0.05).

CONCLUSIONS

These data confirm that anterior spinal fusion techniques result in a mean shorter fusion of 1.5 vertebral segments/patient when compared to posterior spinal fusion techniques with respect to the position of the lowest instrumented and stable vertebrae for "single overhang" thoracic (Lenke 1A/B) curves. However, because this is a retrospective multicenter study over 10 years, it represents various posterior spinal fusion techniques that do not include all pedicle screw constructs.

Standardization of criteria for adolescent idiopathic scoliosis brace studies: SRS Committee on Bracing and Nonoperative Management

STUDY DESIGN

Literature review.

OBJECTIVE

To establish consistent parameters for future adolescent idiopathic scoliosis bracing studies so that valid and reliable comparisons can be made.

SUMMARY OF BACKGROUND DATA

Current bracing literature lacks consistency for both inclusion criteria and the definitions of brace effectiveness.

METHODS

A total of 32 brace treatment studies and the current bracing in adolescent idiopathic scoliosis proposal were analyzed to: (1) determine inclusion criteria that will best identify those patients most at risk for progression, (2) determine the most appropriate definitions for bracing effectiveness, and (3) identify additional variables that would provide valuable information.

RESULTS

Early brace studies lacked clarity in their inclusion criteria. In more recent studies, inclusion criteria have narrowed considerably to include primarily those patients most at risk for curve progression who may benefit from the use of a brace. Brace effectiveness was usually defined by various degrees of curve progression at maturity. Less frequently, it was defined by the resultant curve magnitude at maturity, whether or not surgical intervention was needed, or if there was change to another brace.

CONCLUSIONS

Optimal inclusion criteria for future adolescent idiopathic scoliosis brace studies consist of: age is 10 years or older when brace is prescribed, Risser 0-2, primary curve angles 25 degrees -40 degrees , no prior treatment, and, if female, either premenarchal or less than 1 year postmenarchal. Assessment of brace effectiveness should include: (1) the percentage of patients who have < or =5 degrees curve progression and the percentage of patients who have > or =6 degrees progression at maturity, (2) the percentage of patients with curves exceeding 45 degrees at maturity and the percentage who have had surgery recommended/undertaken, and (3) 2-year follow-up beyond maturity to determine the percentage of patients who subsequently undergo surgery. All patients, regardless of subjective reports on compliance, should be included in the results (intent to treat). Every study should provide results stratified by curve type and size grouping.

Assessment of trunk balance in thoracic scoliosis

STUDY DESIGN

A retrospective radiographic review was undertaken in patients with idiopathic thoracic scoliosis.

OBJECTIVES

To determine if a mathematical relationship exists between the 2 methods used to assess trunk balance (lateral trunk shift [LTS] and thoracic apical vertebral translation [AVT]), and to determine if one of these measurements can satisfactorily predict the value of the other.

SUMMARY OF BACKGROUND DATA

No previous reports exist, to our knowledge, comparing these 2 methods used to asess trunk balance.

METHODS

Coronal balance (CB), LTS, thoracic AVT, and curve magnitude were measured from standing preoperative posteroanterior radiographs of 91 patients with Lenke 1A/1B curves. The data were analyzed to determine if predictive relationships existed between LTS and thoracic AVT alone or between LTS and the sum of CB and thoracic AVT.

RESULTS

A statistically significant relationship was shown between LTS and the sum of thoracic AVT and CB. In general, the LTS can be estimated by taking two thirds of the sum of thoracic AVT and CB (in centimeters) and subtracting 0.8. This relationship weakened as CB improved. The relationship between LTS and AVT was not statistically significant when CB was excluded.

CONCLUSIONS

In patients with thoracic idiopathic scoliosis, if the CB and thoracic AVT values are known, then the LTS can be reliably estimated. The use of correct terminology for describing trunk balance and CB is important if valid comparisons of spinal deformity literature are desired.

Nonoperative clubfoot treatment using the French physical therapy method

Ninety-eight patients (142 clubfeet) treated nonoperatively by the French physical therapy method were reviewed to determine the effectiveness of this technique. All were 3 months old or less when treatment began and were rated for initial clubfoot severity using the Dimeglio scale (moderate, severe, very severe). Follow-up averaged 35 months (range 20-62 months). Forty-two percent of the feet needed no surgery to achieve a plantigrade position, 9% needed heelcord tenotomies, 29% needed posterior releases, and 20% needed comprehensive posteromedial releases. The Dimeglio scale was prognostic for outcomes, with moderate feet having the best results and very severe feet having the worst results. The French physical therapy method significantly reduced the need for operative intervention at the authors' institution.

Nonsurgical management of idiopathic clubfoot

Because nonsurgical management was thought not to yield adequate correction and a durable result, most children with idiopathic clubfoot have undergone surgery with extensive posteromedial and lateral release. However, surgical management caused residual deformity, stiffness, and pain in some children; thus, the favorable long-term results with the Ponseti and French methods of nonsurgical management have garnered interest. The Ponseti method consists of manipulation and casting of idiopathic clubfeet; the French method consists of physiotherapy, taping, and continuous passive motion. Careful evaluation of the techniques and results of these two approaches may increase their use and decrease or minimize the use of surgical management and thus the associated morbidity resulting from extensile releases.

Analysis of patient and parent assessment of deformity in idiopathic scoliosis using the Walter Reed Visual Assessment Scale

OBJECTIVES

This study evaluates the Walter Reed Visual Assessment Scale (WRVAS) compared with clinical parameters and written descriptions of the deformity from idiopathic scoliosis patients and their parents.

SUMMARY OF BACKGROUND DATA

The WRVAS demonstrates seven visible aspects of spinal deformity in an analogue scale. Higher scores reflect worsening deformity.

MATERIALS AND METHODS

The WRVAS was administered to 182 idiopathic scoliosis patients at four centers in conjunction with open-ended questions about patients' and their parents' perceptions of their spinal deformity. The open-ended responses were categorized as either "deformity noted" or "no deformity noted."

RESULTS

WRVAS scores strongly correlate with curve magnitude (P = 0.01) and clearly differentiates curves of 30 degrees or more from lesser curves. Among treatment groups, patients with surgery recommended had significantly higher scores than that of other patients. The instrument differentiated those noting no deformity from those noting a deformity. The correlation between patients' and parents' scores was high (Spearman's rho = 0.8). When a deformity was noted, parents gave higher scores than did their children for rib prominence, shoulder level, scapular rotation, and the total score, but not for the other dimensions.

CONCLUSIONS

Increasing scores of the WRVAS are strongly correlated with curve magnitude lending construct validity to this type of assessment tool. Patients with "surgery recommended" report more visible deformity on the scale than observed, braced, and postoperative patients, supporting the hypothesis that surgery improves the perceived appearance. Parents perceive more deformity of the ribs and shoulders more than did the patients, but other aspects of the deformity are identified equally. WRVAS scores correlate significantly with curve magnitude and treatment. Parents and patients have similar scores, but with parents perceiving more deformity of the ribs and shoulders than patients.

Comparison of reliability between the Lenke and King classification systems for adolescent idiopathic scoliosis using radiographs that were not premeasured

STUDY DESIGN

Multisurgeon comparison of two radiographic scoliosis curve classification systems was performed.

OBJECTIVE

To determine the reliability of the King and Lenke classifications systems for adolescent idiopathic scoliosis using radiographs that had not been premeasured.

SUMMARY OF BACKGROUND DATA

Recent studies introducing the new Lenke classification system for idiopathic scoliosis have reported reliability improved over that of the King classification system. This newer classification system evaluates three different parameters (curve type, lumbar modifier, and sagittal thoracic modifier) and then combines them. The reliability of both classification systems had been determined using radiographs in which all of the curves had been premeasured (recorded on the radiographs) before review by examiners. However, in a normal clinical situation, spine surgeons need to determine the Cobb angles independently, thus introducing another variable.

METHODS

On two separate occasions, four orthopedic surgeons independently evaluated preoperative radiographs (standing posteroanterior, lateral, and two supine side-bending views) of 50 patients with adolescent idiopathic scoliosis. All measurements had been removed on every radiograph before each evaluation. The results were determined by calculating the average percentage of intraobserver and interobserver agreement. Reliability was quantified using kappa statistics.

RESULTS

The King classification demonstrated good intraobserver and fair interobserver reliability. Intraobserver percentage of agreement averaged 83.5% (kappa coefficient, 0.81). Interobserver percentage of agreement averaged 68.0% (kappa coefficient, 0.61). All three parameters of the overall Lenke curve classification demonstrated fair reliability. Intraobserver percentage of agreement averaged 65.0% (kappa coefficient, 0.60). Interobserver percentage of agreement averaged 55.5% (kappa coefficient, 0.50). When the Lenke curve type was examined separately, intraobserver percentage of agreement averaged 81.5% (kappa coefficient, 0.76) and interobserver percentage of agreement averaged 71.5% (kappa coefficient, 0.64). The results for this variable (curve type) were similar to those for the King classification. For the Lenke lumbar modifier, the percentage of agreement and reliability were excellent. For the sagittal thoracic modifier, the percentage of agreement was good, but the kappa values were low because of an extreme imbalance in the grouping of hypokyphotic, normal, and hyperkyphotic spines.

CONCLUSIONS

In this study, with each investigator performing the radiographic measurements, the King classification was found to be better than had been reported recently. The Lenke classification system for adolescent idiopathic scoliosis was found to be less reliable than previously reported when the radiographs were premeasured. This was particularly true when all three parameters of this new classification system were combined. This difference in reliability of the Lenke classification between studies can be attributed to the additional variable of determining the Cobb measurements on each of the unmarked radiographs. Although this new classification system has limitations with respect to interobserver and intraobserver reliability, for planning operative treatment, it offers a more comprehensive radiographic evaluation of patients with adolescent idiopathic scoliosis than previous systems.

A comparison of single-rod instrumentation with double-rod instrumentation in adolescent idiopathic scoliosis

STUDY DESIGN

A consecutive series of patients with idiopathic scoliosis treated with single-rod instrumentation was followed prospectively. Outcomes were compared with results obtained from a retrospective review of a consecutive series of patients treated with double-rod instrumentation.

OBJECTIVE

To compare single-rod instrumentation with segmental fixation with double-rod instrumentation for the treatment of adolescent idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

Mechanical testing of single-rod instrumentation with segmental fixation at every level showed it to be as resistant to torsion as a double-rod construct. A clinical trial was initiated to document the clinical outcome in single-rod patients.

METHODS

A total of 43 of 51 consecutive patients underwent spinal fusion with a single rod. Outcome was evaluated at a minimum of 2 years after surgery. The control group comprised 103 patients who had standard double-rod instrumentation at the same institution.

RESULTS

The single- and double-rod groups were similar with respect to age, sex, curve type, length of follow-up, curve magnitude, and best bend. For King III-V curves undergoing posterior spinal fusion, there was significantly less blood loss in the single-rod group (703 mL vs 1011 mL), less cell saver collection (189 mL vs 367 mL), and less operating time (220 minutes vs 260 minutes). Blood loss and operating time were not different for patients with King I and King II curves. There were eight patients (19%) requiring reoperation because of hardware-related problems in the single-rod group compared with four (4%) in the double-rod group. There were nine patients (21%) with broken rods in the single-rod group, six of whom were symptomatic and five of whom required reoperation. Two patients required multiple operations because of pseudarthrosis in the single-rod group. There were no broken rods in the double-rod group. The single-rod group had 2 early postoperative infections and no late infections compared with 10 late infections in the double-rod group. There was a statistically significant relationship between hardware problems and fusion below L1 in the single-rod group.

CONCLUSION

Because of rod failure, single-rod instrumentation should be considered only in curves that can be instrumented to L1 and higher.

Hemodilution as a method to reduce transfusion requirements in adolescent spine fusion surgery

STUDY DESIGN

A case-control study.

OBJECTIVES

1) To determine if hemodilution adequately meets the transfusion needs in children who undergo posterior spinal fusion for idiopathic scoliosis and 2) to compare the efficacy of the various methods used to reduce the risk of allogeneic blood transfusion at the authors' institution.

SUMMARY OF BACKGROUND DATA

Methods to reduce blood loss and avoid allogeneic blood transfusion caused by extensive spinal surgery in adolescents include 1) autologous blood predonation, 2) controlled hypotensive anesthesia, 3) intraoperative salvage of shed blood (cell saver), 4) acute normovolemic hemodilution, and 5) transfusion decisions by clinical judgment rather than by a preset value of hemoglobin. Although all methods have some efficacy, it is not clear which methods, separate or combined, are best in the adolescent scoliosis population.

METHODS

Hemodilution, hypotensive anesthesia, and cell saver were used in 43 children between June 1996 and July 1997. A comparison group (43 children) underwent similar surgery with hypotensive anesthesia and cell saver, but no hemodilution (between July 1995 and December 1996). These two groups were similar with respect to means of age, levels of instrumentation, magnitude of curvature, estimated blood volume, mean arterial pressure, duration of surgery, duration of anesthesia, estimated blood loss, volume returned from cell saver, volume in the hemovac drain, and length of hospitalization. The groups differed in preoperative hemoglobin and hematocrit and in volume of crystalloid used.

RESULTS

Transfusions were given to 34 of 43 patients (79%) in the nonhemodilution group. These patients received 61 units of packed cells (57 autologous, 2 donor directed, and 2 allogeneic). In comparison, 16 of 43 patients (37%) in the hemodilution group required transfusion. They received 16 units of packed cells (15 autologous and 1 allogeneic). There was no significant difference between the groups with respect to postoperative hemoglobin and hematocrit immediately after surgery (hemodilution, 10.2/29.2; nonhemodilution, 10.0/29.1), postoperative day 1 (hemodilution, 9.2/26.9; nonhemodilution, 9.2/27.3), and postoperative day 2 (hemodilution 9.0/26.4; nonhemodilution, 9.2/27.1). There were non complications related to the technique of hemodilution in the 43 patients of this group. Cell saver was used in all patients, but sufficient volume to return blood to the patient was available in only 23 hemodilution patients (mean volume, 230 mL) and 25 nonhemodilution patients (mean volume, 215 mL). In only two patients of each group (< 5%) did the volume returned prevent the absolute need for additional transfusions.

CONCLUSIONS

Hemodilution was safely used as a method to satisfy the perioperative transfusion requirements of adolescents undergoing extensive spinal surgery. By allowing patients to arrive at surgery with a higher preoperative hemoglobin and hematocrit, and by decreasing the quantity of predonated autologous blood-collected and therefore used, the hemodilution method may indirectly decrease the quantity of postoperative autologous transfusions in this population. Cell saver was not shown to be effective, and its selective use is recommended.

Back pain in childhood and adolescence

A variety of disorders can account for back pain in the child or adolescent (Outline 1). Some of these can result in significant morbidity if not properly diagnosed and treated. Fortunately, nearly all can be correctly diagnosed by taking a thorough medical history, performing a complete physical examination, and obtaining appropriate imaging and laboratory studies. Although back pain in children and adolescents may result from overuse or minor trauma and will respond to rest and anti-inflammatories, this review should enable the orthopaedist to systematically recognize those back disorders in need of more aggressive medical intervention.