Marc A. Asher

Bio: Marc A. Asher is an academic researcher from University of Kansas. The author has contributed to research in topics: Scoliosis & Trunk. The author has an hindex of 31, co-authored 78 publications receiving 5004 citations.

Dual growing rod technique for the treatment of progressive early-onset scoliosis: a multicenter study.

Abstract: Study design A retrospective case review of children treated with dual growing rod technique at our institutions. Patients included had no previous surgery and a minimum of 2 years follow-up from initial surgery. Objectives To determine the safety and effectiveness of the previously described dual growing rod technique in achieving and maintaining scoliosis correction while allowing spinal growth. Summary of background data Historically, the growing rod techniques have used a single rod and the reported results have been variable. There has been no published study exclusively on the results of dual growing rod technique for early-onset scoliosis. Methods From 1993 to 2001, 23 patients underwent dual growing rod procedures using pediatric Isola instrumentation and tandem connectors. Diagnoses included infantile and juvenile idiopathic scoliosis, congenital, neuromuscular, and other etiologies. All had curve progression over 10 degrees following unsuccessful bracing or casting. Of 189 total procedures within the treatment period, 151 were lengthenings with an average of 6.6 lengthenings per patient. Analysis included age at initial surgery and final fusion (if applicable), number and frequency of lengthenings, and complications. Radiographic evaluation included measured changes in scoliosis Cobb angle, kyphosis, lordosis, frontal and sagittal balance, length of T1-S1 and instrumentation over the treatment period, and space available for lung ratio. Results The mean scoliosis improved from 82 degrees (range, 50 degrees-130 degrees) to 38 degrees (range, 13 degrees-66 degrees) after initial surgery and was 36 degrees (range, 4 degrees-53 degrees) at the last follow-up or post-final fusion. T1-S1 length increased from 23.01 (range, 13.80-31.20) to 28.00 cm (range, 19.50-35.50) after initial surgery and to 32.65 cm (range, 25.60-41.00) at last follow-up or post-final fusion with an average T1-S1 length increase of 1.21 cm per year (range, 0.13-2.59). Seven patients reached final fusion. The space available for lung ratio in patients with thoracic curves improved from 0.87 (range, 0.7-1.1) to 1.0 (range, 0.79-1.23, P = 0.01). During the treatment period, complications occurred in 11 of the 23 patients (48%), and they had a total of 13 complications. Four of these patients (17%) had unplanned procedures. Following final fusion, 2 patients required extensions of their fusions because of curve progression and lumbosacral pain. Conclusion The dual growing rod technique is safe and effective. It maintains correction obtained at initial surgery while allowing spinal growth to continue. It provides adequate stability, increases the duration of treatment period, and has an acceptable rate of complication compared with previous reports using the single rod technique.

Adolescent idiopathic scoliosis: natural history and long term treatment effects

Abstract: Adolescent idiopathic scoliosis is a lifetime, probably systemic condition of unknown cause, resulting in a spinal curve or curves of ten degrees or more in about 2.5% of most populations. However, in only about 0.25% does the curve progress to the point that treatment is warranted. Untreated, adolescent idiopathic scoliosis does not increase mortality rate, even though on rare occasions it can progress to the >100° range and cause premature death. The rate of shortness of breath is not increased, although patients with 50° curves at maturity or 80° curves during adulthood are at increased risk of developing shortness of breath. Compared to non-scoliotic controls, most patients with untreated adolescent idiopathic scoliosis function at or near normal levels. They do have increased pain prevalence and may or may not have increased pain severity. Self-image is often decreased. Mental health is usually not affected. Social function, including marriage and childbearing may be affected, but only at the threshold of relatively larger curves. Non-operative treatment consists of bracing for curves of 25° to 35° or 40° in patients with one to two years or more of growth remaining. Curve progression of ≥ 6° is 20 to 40% more likely with observation than with bracing. Operative treatment consists of instrumentation and arthrodesis to realign and stabilize the most affected portion of the spine. Lasting curve improvement of approximately 40% is usually achieved. In the most completely studied series to date, at 20 to 28 years follow-up both braced and operated patients had similar, significant, and clinically meaningful reduced function and increased pain compared to non-scoliotic controls. However, their function and pain scores were much closer to normal than patient groups with other, more serious conditions. Risks associated with treatment include temporary decrease in self-image in braced patients. Operated patients face the usual risks of major surgery, a 6 to 29% chance of requiring reoperation, and the remote possibility of developing a pain management problem. Knowledge of adolescent idiopathic scoliosis natural history and long-term treatment effects is and will always remain somewhat incomplete. However, enough is know to provide patients and parents the information needed to make informed decisions about management options.

The reliability and concurrent validity of the scoliosis research society-22 patient questionnaire for idiopathic scoliosis.

Abstract: STUDY DESIGN Outcome study to determine response distribution, internal consistency, reproducibility, and concurrent validity of the Scoliosis Research Society-22 (SRS-22) health-related quality-of-life (HRQL) questionnaire. OBJECTIVES Further refinement of an HRQL questionnaire specific for idiopathic scoliosis. SUMMARY OF BACKGROUND DATA Previous experience with the original and modified SRS HRQL questionnaires suggested a need for further refinement and more complete validation. METHODS The SRS-22 and Short Form 36 (SF-36) HRQL questionnaires were mailed to 83 previously surveyed postoperative idiopathic scoliosis patients. RESULTS Fifty-eight (70%) patients returned the first set of questionnaires. Their average age at surgery was 14.6 years, and their average follow-up interval since surgery was 10.8 years. Fifty-one (88%) of the 58 returned the second set of questionnaires an average of 28 days later. The psychometric attributes of the instruments were comparable: score distribution, SRS-22 56.9% ceiling and 1.7% floor, SF-36 79.3% ceiling and 1.7% floor; internal consistency (Cronbach alpha), SRS-22 0.92 to 0.75, SF-36 0.91 to 0.36; and reproducibility (intraclass correlation coefficient), SRS-22 0.96 to 0.85, SF-36 0.92 to 0.61. Concurrent validity, determined by Pearson Correlation Coefficients between SRS-22 and SF-36 domains, was 0.70 or greater ( < 0.0001) for 17 relevant comparisons. CONCLUSION The SRS-22 HRQL questionnaire is reliable with internal consistency and reproducibility comparable to SF-36. In addition, it demonstrated concurrent validity when compared to SF-36. It is shorter and more focused on the health issues related to idiopathic scoliosis than SF-36.

Spinal column retaining apparatus

Abstract: An apparatus for retaining vertebrae of a spinal column in a desired spatial relationship includes a fastener having a first end portion for engaging a vertebra. A connector member interconnects the fastener and a longitudinal member positionable along the spinal column. The connector member includes a clamp for clamping the longitudinal member to the connector member. The fastener extends through a slot in the connector member to permit adjustment of the distance between the axis of the fastener and the axis of the longitudinal member. The axis of the fastener is spaced from the clamp a distance measured along the axis of the longitudinal member when the connector member interconnects the fastener and the longitudinal member.

Dual growing rod technique followed for three to eleven years until final fusion: the effect of frequency of lengthening.

Abstract: STUDY DESIGN Retrospective case review of children completing dual growing rod treatment at our institutions. Patients had a minimum of 2 years follow-up. OBJECTIVE To identify the factors influencing dual growing rod treatment outcome followed to final fusion. SUMMARY OF BACKGROUND DATA Published reports on dual growing rod technique results for early onset scoliosis demonstrate it to be safe and effective in curve correction and maintenance as well as in allowing spinal growth. METHODS Between 1990 and 2003, 13 patients with no previous surgery and noncongenital curves underwent final fusion. All had preoperative curve progression over 10 degrees after unsuccessful nonoperative treatment. There were 10 females and 3 males. Average age was 6.6 +/- 2.9 years at initial surgery. There were 3 idiopathic, 1 nonspine congenital anomaly, and 9 syndromic patients. Analysis included age at initial surgery and final fusion, number and frequency of lengthenings, and complications. Radiographic evaluation included changes in Cobb angle, T1-S1 length, and instrumentation length over the treatment period. RESULTS Cobb angle improved from 81.0 +/- 23 degrees to 35.8 +/- 15 degrees postinitial and 27.7 +/- 17 degrees after final fusion. Average number of lengthenings was 5.2 +/- 3 at an interval of 9.4 +/- 5 months. T1-S1 length increased from 24.4 +/- 3.4 to 29.3 +/- 3.6 cm postinitial and 35.0 +/- 3.7 cm postfinal fusion. Average growth was 1.46 +/- 0.66 cm/year. Those lengthened at

Congenital dysplasia and dislocation of the hip in children and adults

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JBJS classics: Treatment of scoliosis: Correction and internal fixation by spine instrumentation

Abstract: A new method for the treatment of scoliosis is described in which a metal system of rods and hooks is implanted, and distraction and compression forces applied, to correct the curve and stabilize the treated segments in the corrected position by skeletal fixation. The technique and principles of this method of treatment and a summary of the preliminary results are given.

Properties of acrylic bone cement: state of the art review.

Abstract: Acrylic bone cement occupies a distinctive place in the hierarchy of synthetic biomaterials, because it is the only material currently used for anchoring the prosthesis to the contiguous bone in a cemented arthroplasty. However, the cement is not without its drawbacks. The main one is the role that it has been postulated to play in the aseptic loosening and, hence, clinical life of the arthroplasty. In turn, this role is directly related to the mechanical properties of the cement, especially the resistance to fracture of the cement in the mantle at the cement-prosthesis interface or the cement-bone interface. The present work is a detailed critical review of the recent literature on the properties of bone cement that are considered germane to its use in the stated application. The relevant properties are identified and a case is made for including each of them. Compilations of the values of these properties, obtained under clearly identified conditions, are presented for the six commercial formulations of bone cement in current popular orthopedic use. The gaps and unresolved questions in the current data base, efforts that should be made to address these issues, and research directions are covered.

Are animal models useful for studying human disc disorders/degeneration?

Abstract: Intervertebral disc (IVD) degeneration is an often investigated pathophysiological condition because of its implication in causing low back pain. As human material for such studies is difficult to obtain because of ethical and government regulatory restriction, animal tissue, organs and in vivo models have often been used for this purpose. However, there are many differences in cell population, tissue composition, disc and spine anatomy, development, physiology and mechanical properties, between animal species and human. Both naturally occurring and induced degenerative changes may differ significantly from those seen in humans. This paper reviews the many animal models developed for the study of IVD degeneration aetiopathogenesis and treatments thereof. In particular, the limitations and relevance of these models to the human condition are examined, and some general consensus guidelines are presented. Although animal models are invaluable to increase our understanding of disc biology, because of the differences between species, care must be taken when used to study human disc degeneration and much more effort is needed to facilitate research on human disc material.