Ordinal models to analyze strategy sophistication: Evidence from a learning trajectory efficacy study.

Investigators often rely on the proportion of correct responses in an assessment when describing the impact of early mathematics interventions on child outcomes. Here, we propose a shift in focus to the relative sophistication of problem-solving strategies and offer methodological guidance to researchers interested in working with strategies. We leverage data from a randomized teaching experiment with a kindergarten sample whose details are outlined in Clements et al. (2020). First, we describe our problem-solving strategy data, including how strategies were coded in ways that are amenable to analysis. Second, we explore what kinds of ordinal statistical models best fit the nature of arithmetic strategies, describe what each model implies about problem-solving behavior, and how to interpret model parameters. Third, we discuss the effect of "treatment", operationalized as instruction aligned with an arithmetic Learning Trajectory (LT). We show that arithmetic strategy development is best described as a sequential stepwise process and that children who receive LT instruction use more sophisticated strategies at post-assessment, relative to their peers in a teach-to-target skill condition. We introduce latent strategy sophistication as an analogous metric to traditional Rasch factor scores and demonstrate a moderate correlation them (r = 0.58). Our work suggests strategy sophistication carries information that is unique from, but complimentary to traditional correctness-based Rasch scores, motivating its expanded use in intervention studies.

Adolescent idiopathic scoliosis: a new classification to determine extent of spinal arthrodesis.

BACKGROUND: The lack of a reliable, universally acceptable system for classification of adolescent idiopathic scoliosis has made comparisons between various types of operative treatment an impossible task. Furthermore, long-term outcomes cannot be determined because of the great variations in the description of study groups. METHODS: We developed a new classification system with three components: curve type (1 through 6), a lumbar spine modifier (A, B, or C), and a sagittal thoracic modifier (-, N, or +). The six curve types have specific characteristics, on coronal and sagittal radiographs, that differentiate structural and nonstructural curves in the proximal thoracic, main thoracic, and thoracolumbar/lumbar regions. The lumbar spine modifier is based on the relationship of the center sacral vertical line to the apex of the lumbar curve, and the sagittal thoracic modifier is based on the sagittal curve measurement from the fifth to the twelfth thoracic level. A minus sign represents a curve of less than +10 degrees, N represents a curve of 10 degrees to 40 degrees, and a plus sign represents a curve of more than +40 degrees. Five surgeons, members of the Scoliosis Research Society who had developed the new system and who had previously tested the reliability of the King classification on radiographs of twenty-seven patients, measured the same radiographs (standing coronal and lateral as well as supine side-bending views) to test the reliability of the new classification. A randomly chosen independent group of seven surgeons, also members of the Scoliosis Research Society, tested the reliability and validity of the classification as well. RESULTS: The interobserver and intraobserver kappa values for the curve type were, respectively, 0.92 and 0.83 for the five developers of the system and 0.740 and 0.893 for the independent group of seven scoliosis surgeons. In the independent group, the mean interobserver and intraobserver kappa values were 0.800 and 0.840 for the lumbar modifier and 0.938 and 0.970 for the sagittal thoracic modifier. These kappa values were all in the good-to-excellent range (>0.75), except for the interobserver reliability of the independent group for the curve type (kappa = 0.74), which fell just below this level. CONCLUSIONS: This new two-dimensional classification of adolescent idiopathic scoliosis, as tested by two groups of surgeons, was shown to be much more reliable than the King system. Additional studies are necessary to determine the versatility, reliability, and accuracy of the classification for defining the vertebrae to be included in an arthrodesis.

Do radiographic parameters correlate with clinical outcomes in adolescent idiopathic scoliosis?

STUDY DESIGN: A radiographic assessment has been developed to include coronal, sagittal, and axial parameters. OBJECTIVE: To determine the correlation of postoperative radiographic results and percentage postoperative radiographic improvement with patient clinical self-assessment. SUMMARY OF BACKGROUND DATA: With the increasing interest in outcome studies, the authors wanted to determine whether Scoliosis Research Society clinical questionnaire results would correlate with objective radiographic improvement. INCLUSION CRITERIA: adolescent idiopathic scoliosis treated with anterior or posterior instrumentation, a solid fusion, minimum 2-year follow-up, and a completed postoperative Scoliosis Research Society questionnaire. Seventy-eight patients met the criteria. Measurements included in the radiographic score: Cobb angles of the coronal curve, C7 to the center sacral vertical line, apical translation, apical vertebral rotation, T1 rib angle, end-instrumented vertebrae angulation, angulation of the disc below the end-instrumented vertebra, and curve type. Sagittal measurements included T2-T12, T5-T12, T2-T5, T12-L2, and L1-S1. RESULTS: The preoperative radiographic score of these 78 patients was mean 60.1 +/- 9.7 (range 41-88, maximum radiographic score, 100). The 2-year postoperative radiographic score was mean 83.8 +/- 8.8 (range, 65-100). The median Scoliosis Research Society questionnaire score was 98 +/- 12.3 (range, 58-116, maximum score, 125, showing that the patient is highly satisfied and asymptomatic). The postoperative radiographic score versus the questionnaire score showed a Spearman rank correlation of 0.04 (P = 0.68, little or no correlation throughout). Percentage improvement of the radiographic score versus the questionnaire score showed a Spearman rank correlation of 0.1 (P = 0.38, little or no correlation throughout). CONCLUSION: In this initial group of patients, the radiographic assessment shows a significant improvement between preoperative and 2-year postoperative scores. However, little correlation between the radiographic assessment and the questionnaire scores was found in this adolescent population, suggesting that separate analyses of radiographic and clinical outcome data are required when evaluating results of postoperative scoliosis surgery.

The effect of continued posterior spinal growth on sagittal contour in patients treated by anterior instrumentation for idiopathic scoliosis.

STUDY DESIGN: Retrospective analysis of radiographs on a prospective cohort of patients undergoing anterior instrumentation for thoracic idiopathic scoliosis. OBJECTIVES: To analyze the change in sagittal profile after growth. SUMMARY OF BACKGROUND DATA: The authors previously reported some advantages of anterior instrumentation for treatment of thoracic idiopathic scoliosis. However, postsurgery hyperkyphosis has resulted in some patients, especially those who were skeletally immature at the time of surgery. METHODS: Inclusion criteria required that participants have thoracic idiopathic scoliosis treated with anterior instrumentation and a confirmed solid fusion, no rod breakage, and a minimum follow-up period of 2 years. The 47 patients meeting the criteria were divided into a study group of 10 patients who were Risser 0 at the time of surgery and a control group of 37 patients who were Risser 1 to 5. Progressive sagittal kyphosis was defined as an increase of 10 degrees or more (T5-T12) after surgery. RESULTS: Sagittal progression greater than 10 degrees (average, 15 degrees ) occurred in 6 of 10 patients (60%) in the study group (Risser 0). Five patients progressed from 10 degrees to 19 degrees, and one patient from 20 degrees to 30 degrees. In contrast, sagittal progression occurred in only 10 of 37 patients (27%) in the control group (Risser 1 to 5). CONCLUSIONS: Some patients with thoracic adolescent idiopathic scoliosis treated with anterior instrumentation may be at risk for progressive sagittal kyphosis secondary to growth. Skeletal immaturity (Risser 0) appears to be a risk factor. In these immature patients, preserving the sagittal profile with intervertebral spacers, rigid rods, and bone graft (allowing for an average 15 degrees increase of kyphosis with growth) may be appropriate.

Spontaneous lumbar curve coronal correction after selective anterior or posterior thoracic fusion in adolescent idiopathic scoliosis.

STUDY DESIGN: Retrospective review of anterior and posterior fusions for treatment of adolescent idiopathic thoracic scoliosis. OBJECTIVES: To evaluate both the instrumented thoracic and the spontaneous lumbar curve corrections after treatment of the primary thoracic scoliosis by either anterior or posterior fusion. SUMMARY OF BACKGROUND DATA: Recent reports of thoracic scoliosis fusions have concentrated on the thoracic correction obtained by posterior segmental instrumentation systems. Coronal decompensation occurring because of curve progression with imbalance of the unfused lumbar spine has also been investigated. No report comparing spontaneous lumbar curve response after selective anterior versus posterior thoracic scoliosis fusions are available. METHODS: One hundred twenty-three cases of primary thoracic-compensatory lumbar adolescent idiopathic scoliosis were treated by selective thoracic instrumentation and fusion with either an anterior (n = 70) or posterior (n = 53) single approach. Thoracic and lumbar Cobb measurements and lumbar apical translation parameters were assessed before surgery, 1 week after surgery, and 2 years after surgery on upright coronal radiographs. All patients had a minimum 2-year follow-up. RESULTS: At 2-year follow-up, the percentage of thoracic curve correction was superior for the anterior (58%) versus the posterior (38%) group (P < 0.05), whereas the spontaneous lumbar curve correction was also superior for the anterior (56%) group versus the posterior (37%) group for all curve types investigated (P < 0.05). Both treatment groups consistently improved lumbar apical positioning after the thoracic fusion procedure. CONCLUSIONS: Spontaneous lumbar curve correction occurs consistently after both selective anterior and posterior thoracic fusion implying intrinsic ability of the lumbar spine to follow thoracic spine correction. In the current study, using multisegmented hook-rod systems posteriorly with intentional limitation of posterior thoracic correction to avoid decompensation, instrumented thoracic and spontaneous lumbar curve correction was statistically better after anterior thoracic instrumentation and fusion, with the results most dramatic for lumbar curve Type C (true King II curves).

Proximal kyphosis after posterior spinal fusion in patients with idiopathic scoliosis.

STUDY DESIGN: For this retrospective study, preoperative and postoperative radiographs of posterior spinal fusions for idiopathic scoliosis were reviewed. OBJECTIVES: To determine the prevalence and possible causes of proximal kyphosis after posterior spinal fusion for idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Proximal kyphosis has been anecdotally noted after the insertion of Harrington rods and after use of the new posterior multisegmented hook/rod systems. In this study no attempt was made to determine whether this condition is painful or an adverse outcome for the patient or just a radiographic abnormality; however, it is suspected that this may be a problem in the long term, and it may be worthwhile to try to avoid it if predictive values can be ascertained. METHODS: Patients with adolescent idiopathic scoliosis who had undergone posterior spinal fusion not extending above T3 with good-quality radiographs of the proximal thoracic spine and a minimum 2-year follow-up were studied. Of the 106 patients who underwent posterior spinal fusion from 1990 through 1994, 69 met the inclusion criteria. Abnormal kyphosis from T2 to the proximal level of the instrumented fusion was defined as kyphosis of more than 5 degrees above the summed normal angular segments. RESULTS: Of 69 patients, 37 (54%) had normal proximal kyphosis, and 32 (46%) of the 69 were defined as having abnormal proximal kyphosis. In the 32 patients with abnormal proximal kyphosis, the measurement from T2 to the fusion was 10.3 degrees before surgery and 21.2 degrees after surgery. The normal group had kyphosis measuring 2.7 degrees from T2 to fusion before surgery and 5.3 degrees after surgery (P < 0.00001). Junctional kyphosis in the kyphosis group measured 6.5 degrees before surgery and 12.6 degrees after surgery, compared with normal kyphosis of 1.7 degrees and 2.6 degrees, respectively (P < 0.00001). When analyzing who would develop proximal kyphosis, preoperative one-level junctional kyphosis of more than 5 degrees above the proposed proximal instrumented vertebrae was shown to have the highest sensitivity (78%) and specificity (84%). CONCLUSIONS: In this study, 32 (46%) of 69 patients had abnormal proximal kyphosis after undergoing posterior spinal fusion. A preoperative junctional kyphosis of more than 5 degrees above the proposed proximal instrumented vertebrae indicates that extending the fusion to a higher level in the thoracic spine would be beneficial in avoiding this problem.

Comparison of anterior and posterior instrumentation for correction of adolescent thoracic idiopathic scoliosis.

STUDY DESIGN: This was a prospective study of two cohort groups of patients (one group receiving anterior instrumentation and the other posterior instrumentation) receiving treatment for thoracic idiopathic scoliosis. OBJECTIVE: To present the 2-year postoperative results of a prospective multicenter study comparing the use of anterior instrumentation with that of posterior multisegmented hook instrumentation for the correction of adolescent thoracic idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Despite reports of satisfactory results, problems have been reported with posterior systems, including worsening of the lumbar curve after surgery and failure to correct hypokyphosis. Theoretically, the advantages of anterior instrumentation include prevention of lumbar curve decompensation by shortening the convexity of the thoracic curve. In addition, by removing the disc, better correction of thoracic hypokyphosis could be obtained. METHODS: Seventy-eight patients who underwent an anterior spinal fusion using flexible threaded rods and nuts (Harms-MOSS instrumentation, De Puy-Motech-Acromed, Cleveland, OH) were analyzed and compared with 100 patients who underwent posterior spinal fusion with multisegmented hook systems. Parameters of comparison included coronal and sagittal correction, balance, distal lumbar fusion levels, and complication. All patients had idiopathic thoracic curves of King Types II to V. The average age at surgery was 14 years in each group, the average preoperative curve 57 degrees, and the minimum duration of follow-up for all patients 24 months. All data were collected prospectively and analyzed via Epl into statistical analysis (Centers of Disease Control, Atlanta, GA). RESULTS: Average coronal correction of the main thoracic curve was 58% in the anterior group and 59% in the posterior group (P = 0.92). Analysis of sagittal contour showed that the posterior systems failed to correct a preoperative hypokyphosis (sagittal T5 to T12 less than 20 degrees) in 60% of cases, whereas 81% were normal postoperatively in the anterior group. However, hyperkyphosis (sagittal T5 to T12 greater than 40 degrees) occurred after surgery in 40% of the anterior group when the preoperative kyphosis was greater than 20 degrees. Postoperative coronal balance was equal in both groups. An average of 2.5 (range, 0-6) distal fusion levels were saved using the anterior spinal instrumentation according to the criteria used for determining posterior fusion levels in this study. Selective fusion of the thoracic curve (distal fusion level T11, T12, L1) was performed in 76 of 78 patients (97%) in the anterior group as compared with only 18 of 100 (18%) in the posterior group. Surgically confirmed pseudarthrosis occurred in 4 of 78 patients (5%) in the anterior group and in 1 of 100 patients (1%) in the posterior group (P = 0.10). Loss of correction greater than 10 degrees occurred in 18 of 78 patients (23%) in the anterior group and in 12 of 100 patients (12%) in the posterior group (P = 0.01). Implant breakage occurred in 24 patients (31%) of the anterior group and in only 1 patient (1%) of the posterior group. CONCLUSIONS: 1) Coronal correction and balance were equal in both the anterior and posterior groups, even though the anterior group had the majority of curves (97%) fused short or to L1, whereas only 18% were fused short or to L1 in the posterior group. 2) In the anterior group there was a better correction of sagittal profile in those with a preoperative hypokyphosis less than 20 degrees. However, hyperkyphosis (with a mean of 54 degrees) occurred in 40% of those in the anterior group with a preoperative kyphosis of more than 20 degrees. 3) An average of 2.5 lumbar levels can be saved with anterior fusion and instrumentation according to the criteria used for choosing posterior fusion levels in this study. 4) Using the 3.2-mm flexible rod in this study, loss of correction, pseudarthrosis, and rod breakage were unacceptably highe

Intraobserver and interobserver reliability of the classification of thoracic adolescent idiopathic scoliosis.

The system described by King et al. is the standard method for the classification of thoracic adolescent idiopathic scoliosis. Although it is widely used and referenced, its reliability and reproducibility among scoliosis surgeons are unknown. We used a scoliosis case-presentation format to examine the interobserver and intraobserver reliability of the classification of thoracic adolescent idiopathic scoliosis with the system of King et al. Eight active, current members of the Scoliosis Research Society reviewed twenty-seven full-length radiographs that had been made before operative correction of the scoliotic deformity. On the basis of these images, which included posteroanterior and lateral radiographs made with the patient standing as well as right and left forced-side-bending radiographs made with the patient supine, the reviewers assigned a type to each curve according to the classification system of King et al. Kappa coefficients were used to test statistical reliability. The mean interobserver reliability of the classification was only 64 per cent (range, 54 to 77 per cent) when the responses of seven of the reviewers were compared with those of one of the originators of the classification. The mean kappa coefficient was 0.49 (range, 0.27 to 0.73), which indicates poor reliability. When each reviewer's responses were compared with those of the other reviewers, the reliability was similarly poor (interobserver reliability, 55 per cent [range, 33 to 81 per cent] and mean kappa coefficient, 0.40 [range, 0.21 to 0.63]). Intraobserver reliability was evaluated in a trial in which five reviewers in a group setting were shown the same radiographs in a different order at two different viewings. Comparison of the results at the two viewings revealed a mean intraobserver reliability of 69 per cent (range, 56 to 85 per cent) and a mean kappa coefficient of 0.62 (range, 0.34 to 0.95), which indicates fair reliability. The current method of classification of adolescent idiopathic scoliosis does not appear to have sufficient intraobserver or interobserver reliability among scoliosis surgeons to portray curve types accurately. Thus, it may not help to guide treatment with use of modern spinal fixation methods.

Comparison of thoracoscopic and open thoracic discectomy in a live ovine model for anterior spinal fusion.

STUDY DESIGN: The authors undertook a randomized comparison of 30 thoracoscopic and 30 open thoracic discectomies for anterior spinal fusion in a live sheep model. OBJECTIVES: To compare in a live sheep model discectomies performed using a thoracoscopic technique with those using an open thoracotomy technique to validate the efficacy of thoracoscopic disc and end plate removal for potential fusion. SUMMARY OF BACKGROUND DATA: In 1993, Mack and Regan described a technique for video-assisted thoracic surgery that resulted in less morbidity than open techniques. Subsequent reports support the finding that thoracoscopic spinal surgery results in less morbidity. METHODS: Sixty discectomies were performed in 10 live sheep. In each sheep, three randomly selected discectomies were performed thoracoscopically, and, subsequently, three open discectomies were performed. The animal then was killed, and the spine was sectioned and analyzed by computer imaging. RESULTS: Statistical analysis found no significant difference in the amount of disc resected (t' = 1.9639, t0.025, 60 = 2.000, alpha = 0.05). The mean percentage of disc resected was 67.8% (range, 0-92.2%) in the thoracoscopic group and 76.1% (range, 44.9-95.4%) in the open group. More than 50% of the disc was excised in 27 of 30 spines (90%) in the thoracoscopic group and in 29 of 30 (96.7%) in the open group. This difference was not statistically significant (theta 2(0.05, 1) = 3.84, theta 2' = 1.07). CONCLUSION: The findings in this study indicate that the thoracoscopic discectomy technique is equivalent to the open technique in the amount of disc and end plate resected. In addition, these findings suggest that thoracoscopic discectomies provide adequate disc resection to provide for an acceptable fusion rate according to the criteria demonstrated by Bunnell in 1982 and therefore support the efficacy of a thoracoscopic technique for anterior spinal fusion.

Prevalence of perioperative complications after anterior spinal fusion for patients with idiopathic scoliosis.

Anterior spinal fusion (ASF) has been proven to improve curve correction, save motion segments, and decrease the rate of pseudarthrosis when compared with posterior spinal fusion alone. However, in patients with idiopathic scoliosis, the complication rate of the anterior approach to the spine using current techniques has only been scantly defined in the literature. This is a retrospective review of consecutive patients who underwent primary ASF for idiopathic scoliosis to determine the prevalence and types of complications specifically related to the anterior approach. All patients who underwent primary ASFs for idiopathic scoliosis done by one of two orthopaedic surgeons between October 1986 and July 1992 were reviewed. Adequate records were available for 98 of 103 patients. The average age at time of surgery was 22 years (range, 10-60 years). Complications were divided into three groups: major (resulting in permanent sequelae or necessitating a second major operation); minor (resulting in a prolonged hospital stay, necessitating a minor operation, and/or resulting in a significant temporary hardship or persistent minor problem); and insignificant (anything less than minor). One of 98 patients had a major complication (a pelvic deep venous thrombosis that required operative thrombectomy). Twenty-five of 98 patients had 28 complications classified as minor, and 28 of 98 patients had 30 complications classified as insignificant. Smoking was a significant risk factor for the development of minor complications. There was no statistically significant relationship between the development of complications and the degree of curve, the approach used, the procedure performed, or the performance of rib resections. The anterior approach to the spine in patients with idiopathic scoliosis in this series was very safe, with only one major complication in 98 patients. However, minor and insignificant complications were quite common, occurring in 45 of 98 patients (46%). Smoking was a significant risk factor for minor complications.

Natural history of adolescent thoracolumbar and lumbar idiopathic scoliosis into adulthood.

Thirty-four patients with adolescent idiopathic thoracolumbar, lumbar, or lumbar components of double major curves between 20 and 55 degrees were identified. This study group was compared with an age- and sex-matched control group with regard to back pain, radicular symptoms, and perception of handicap. The objectives of this study were to define the natural history of moderate-range adolescent idiopathic thoracolumbar, lumbar, and double major curves with a lumbar component in this range. Studies that exclusively examined the natural history of thoracolumbar and more caudad curves have not been undertaken. Data from other related studies is often clouded by various factors. We reviewed the charts and radiographs of 363 patients with idiopathic scoliosis seen between 1935 and 1975 with available original radiographs. Thirty-four of 65 patients (52%) answered a questionnaire pertaining to severity of pain, functional abilities, and perceived quality of life. The same questionnaire was answered by 31 age- and sex-matched controls for comparison. The average follow-up was 22 years, and average patient age at current follow-up was 36 years. Curves at skeletal maturity measured an average of 35 degrees. On a scale of 1-10 (severe), current low-back pain in the study group was rated a mean of 3.19 versus 1.94 in the control group. Twelve of 34 patients in the study group (35%) reported no back pain, versus 21 of 31 (68%) in the control group. Twenty-four percent of the study group had radicular symptoms compared with 16% of the control group. None of the 34 study patients and 1 control patient underwent surgery for back pain. With an average follow-up of 22 years, the study group reported handicap scores comparable to those of the control group. The average age of the study patients was only 36 years, but it is encouraging that these individuals have continued to do well for at least 20 years past skeletal maturity.

Prevalence of segmental wire breakage using Cotrel-Dubousset instrumentation in the management of idiopathic scoliosis.

STUDY DESIGN: This is a retrospective radiographic and medical record analysis of 77 patients. OBJECTIVES: To determine whether there is an increased prevalence of segmental sublaminar wire breakage associated with the knurled (diamond) pattern machined onto the Cotrel-Dubousset rod as opposed to a smooth rod. SUMMARY OF BACKGROUND DATA: Segmental fixation of vertebral segments with sublaminar wires is a common surgical technique, and the use of sublaminar wires with a knurled Cotrel-Dubousset rod theoretically could cause premature wire breakage. METHODS: Sixty-six patients with idiopathic scoliosis had the Cotrel-Dubousset (knurled rod) system and comprised the study group, and the Texas Scottish Rite Hospital system (smooth rod) was placed in 14 patients, who served as a control group. Serial radiographs after 3, 6, 12, and 24 months were reviewed. All patients had augmentation of their scoliosis constructs with 16-gauge sublaminar wires in the lumbar spine. Minimum follow-up period was 24 months. RESULTS: No wire breakage was noted in any patient. CONCLUSIONS: There is no increased likelihood that the knurled rod pattern will cause wire breakage, provided a solid fusion is obtained.

Evoked and spontaneous electromyography to evaluate lumbosacral pedicle screw placement.

STUDY DESIGN: A prospective study was performed to evaluate the effectiveness of evoked and spontaneous electromyography in predicting pedicle wall breakthrough and subsequent lumbar radiculopathy occurring after placement of pedicle screw instrumentation of the lumbar spine. OBJECTIVES: To correlate cortical breakthrough of the pedicle wall with an electrically evoked electromyography threshold of stimulation, to assess the sensitivity of mechanically evoked electromyography for nerve root irritation, and to correlate postoperative nerve root irritation with intraoperative findings. SUMMARY OF BACKGROUND DATA: Pedicle wall breakthrough has been evaluated by radiographic means and found to be difficult to evaluate. Methods to perform both electrically evoked and mechanically evoked electromyography have been developed more sensitive tests for breakthrough. METHODS: Twenty-five patients receiving 112 pedicle screws were evaluated. RESULTS: Cortical breakthrough was associated with electrically evoked electromyography threshold of less than 11 milliAmps. Not all screws that had broken through the pedicle wall caused a postoperative radiculopathy. Electromyographic activity was sensitive to nerve root stimulation. CONCLUSIONS: Measuring the electrically evoked electromyography threshold of stimulation helps to assess pedicle screw placement. Mechanically evoked electromyography indicates intraoperative nerve root displacement. Postoperative radiculopathy correlated with pedicle wall breakthrough, but did not occur in every case.

Are there indications for partial rib resection in patients with adolescent idiopathic scoliosis treated with Cotrel-Dubousset instrumentation?

In adolescent idiopathic scoliosis the cosmetically unacceptable rib prominence is one of the main reasons patients seek treatment. Ninety-eight patients were reviewed with Cotrel-Dubousset (CD) instrumentation (average follow-up, 27 months; average preoperative curve, 53 degrees) and 27 patients with Harrington instrumentation and rib resection (average follow-up, 43 months; average preoperative curve, 52 degrees). Of the 98 patients who had CD instrumentation, 15 underwent concomitant rib resection. Of the 83 patients without rib resection, 71 (72%) were rated satisfactory and 12 unsatisfactory by cosmetic criteria based on residual rib deformity. These results were compared to those of 27 patients receiving Harrington rod instrumentation and rib resection, of whom 23 (85%) were rated as satisfactory. All 15 patients with CD and rib resection were rated satisfactory. The CD patients were then redivided into two groups (rib resection indicated or rib resection not indicated) as follows: the 12 unsatisfactory CD patients without rib resection (in whom a rib resection should have been done) were grouped with the 15 CD patients who underwent rib resection, for a total of 27 rib resections indicated, or 28%. This group was compared to the 71 satisfactory CD patients without rib resection (rib resection not indicated). Patients with a rib prominence of > 15 degrees preoperatively had or should have had a rib resection. Patients with a higher chance of needing rib resection included those with a curve severity greater than 60 degrees, curve flexibility less than 20%, a preoperative rib prominence > 10 degrees, or intraoperative curve correction of less than 50%.

Design and development of a biomechanical apparatus to test the integrity of the Luque orthopaedic internal bone-plate fixation system.

This paper describes the design and construction of a biomechanical model that will determine the pull-out strengths and fatigue failure of internal fixation devices used at the lumbosacral junction. Fusions at this junction have the highest failure rate. It is suggested that devices that successfully fix this vertebral unit will be effective at other levels of the spine. A model that tests any device designed for use at the lumbosacral junction will therefore provide a uniform measure of the effectiveness of different kinds of instrumentation at the L5-S1 vertebral unit. It will also provide predictive values for fixation systems at other spinal levels. A real-time data-acquisition system was also designed and used to define and determine the failure of the Luque orthopaedic bone-plate fixation device.

Salvage and reinfusion of postoperative sanguineous wound drainage. A preliminary report.

Thirty-five patients who were to have posterior spinal arthrodesis, total hip arthroplasty, or total knee arthroplasty were entered into one of two groups: Group A, to receive unwashed, filtered sanguineous drainage from the wound, or Group B, to receive washed, filtered drainage. The purpose of this prospective study was to evaluate the safety, efficacy, and difficulty of reinfusion of washed compared with unwashed drainage that had been salvaged from the wound after an orthopaedic operation. The sixteen patients in Group A received a mean of 475 milliliters of unwashed drainage for each total knee arthroplasty, 427 milliliters for each total hip arthroplasty, and ten milliliters for the one posterior spinal arthrodesis. The complications included immediate hypotension (two patients), hyperthermia (one patient), and hypotension five hours after reinfusion (one patient). The latter patient died, four days after the operation, of a massive myocardial infarction. The nineteen patients in Group B received a mean of 193 milliliters of washed, filtered drainage for each total knee arthroplasty, 203 milliliters for each total hip arthroplasty, and 179 milliliters for each posterior spinal arthrodesis. Salvage and reinfusion of washed drainage from the wound caused no problems in these patients.

Anterior cervical discectomy and fusion.

A retrospective review of 94 patients who had undergone anterior cervical discectomy and fusion was performed to analyze the result in patients who had a diagnosis of posterolateral spondylosis, disc herniation, or both. Although in 23 of 94 patients additional adjacent asymptomatic levels of spondylosis were noted, only the symptomatic levels were addressed in the 94 cases. Postoperatively two cases of dysphagia were noted, as well as a 4% pseudarthrosis rate. There was an 88% good or excellent result when no additional spondylosis was present, but only a 60% good or excellent result when just the symptomatic levels were addressed, leaving unoperated adjacent levels of spondylosis.