Sue Min Lai

Further development and validation of the Scoliosis Research Society (SRS) Outcomes Instrument

Study Design. Outcome study to determine response distribution, internal consistency, and validity of a Modified SRS Outcomes Instrument (MSRSI). Objectives. Refinement and validation of the SRS Outcomes Instrument for idiopathic scoliosis. Summary of Background Data. Experience with the SRS Outcomes Instrument suggested several refinements and the need for validation. Methods. Following experience-based modification, the Modified SRS Outcomes Instrument and Short Form 36 (SF-36) questionnaires were administered to 35 previously surveyed postoperative idiopathic scoliosis patients. Results. Thirty (86%) patients with an average age of 25 years returned the questionnaires at an average of 10 years postoperative. Distribution of scores was acceptable. Internal consistency utilizing Cronbach’s &agr; was 0.80, 0.81, 0.77, 0.89, and 0.88 for pain, self-image/appearance, function/activity, mental health, and satisfaction with surgery, respectively. Validity, determined by Pearson correlation coefficients with comparable SF-36 domains, was 0.70 or greater for 13 of the 14 relevant domains between SF-36 and MSRSI (P < 0.001). Conclusion. The SRS Outcomes Instrument is simple and internally consistent. Based on experience, a number of modifications have been made that improve the instruments scope and internal consistency. Finally, the instrument is valid in comparison to SF-36.

Refinement of the SRS-22 health-related quality of life questionnaire function domain

Study Design. Prospective observational case series. Objectives. To improve the Scoliosis Research Society-22 (SRS-22) Health-Related Quality of Life (HRQL) questionnaire Function domain internal consistency for patients younger than 18 years. Summary of Background Data. During English validation as well as Spanish and Turkish transcultural adaptation studies, low internal consistency of the Function domain was discovered for patients younger than 18 years. The problem was traced to questions 15 (relating to financial considerations) and 18 (relating to going out with friends). Otherwise, the SRS-22 HRQL questionnaire has been shown to be valid and has been successfully translated into Spanish and Turkish. Methods. Based on existing data, question 18s stem and responses were revised without changing its content and added to the SRS-22 questionnaire. Question 15 remained unchanged, and the effect of inclusion or exclusion on domain score was determined. During a 3-month period, the questionnaire was completed by 111 outpatients, including four groups: idiopathic scoliosis age <18 years (n = 37), idiopathic scoliosis age ≥18 years (n = 32), other spinal disorders age <18 years (n = 17), and other spinal disorders age ≥18 years (n = 25). Results. As a result of the revision of question 18, the Function domain internal consistency, Cronbachs alpha, for patients age <18 years was increased from 0.67 to 0.78 for patients with idiopathic scoliosis and from 0.60 to 0.80 for patients with other spinal disorders. Domain internal consistency remained high, 0.77 to 0.96 for all the other domain-patient groupings. Removal of question 15 slightly improved Function domain internal consistency for idiopathic scoliosis patients <18 years old and slightly decreased it for patients <18 years old with other spinal conditions. Conclusion. With a minor revision of question 18 (related to going out) the internal consistency of the SRS-22 Function domain has been improved in idiopathic scoliosis patients <18 years of age. Deletion of question 15 (related to financial considerations) has a variable, small effect depending on patient group. Retention of question 15 is recommended unless a cultural variable, such as differences in healthcare payment schemes, substantially lowers domain psychometric properties.

Safety and efficacy of Isola instrumentation and arthrodesis for adolescent idiopathic scoliosis: two- to 12-year follow-up.

Study Design. Retrospective case series including patient outcome assessment. Objective. To study the safety and efficacy of Isola instrumentation in comparison with similar series. Summary of Background Data. Both the technique and technology used in the surgical treatment of adolescent idiopathic scoliosis continue to evolve, the common theme since the 1980s being provision of instrumentation stable and strong enough to eliminate the need for postoperative immobilization. The purpose of this study is to determine the safety and efficacy of a system deliberately integrating hook, wire, and screw anchors to deliver torsional and countertorsional corrective loads. Methods. A total of 185 consecutive patients, index patient included, were treated by posterior instrumentation and arthrodesis from January 1989 through December 2000. Safety was studied by complications, and reoperation type and occurrence. Effectiveness was studied by deformity correction and health-related quality of life questionnaire response. Variables affecting effectiveness were sought. A total of 179 patients (97%) had outcome assessment at an average of 6 years postoperative, and 176 had radiographic evaluation at an average of 5 years postoperative. Results. There were no deaths, spinal cord or nerve root problems, or acute posterior wound infections. Proven pseudarthrosis occurred in 4 patients (2.2%) and delayed deep wound infection in 2 patients (1.1%). The implant-related reoperation rate was 8% and was necessary more often in the first quarter of the series (17% vs. 4.6%, P = 0.0062). The largest Cobb angle averaged 62° preoperative and 23° at latest follow-up, 63% correction. The largest angle of trunk inclination averaged 16.7° before surgery and 9.9° at latest follow-up, a 39% correction (P < 0.0001). Eighty-eight percent of patients were satisfied or very satisfied with the outcome. The principal problems identified were the need for a stronger transverse connector, stable end-instrumented vertebrae foundations, and convex thoracic anchorage. Conclusions. Isola instrumentation seems to be at least as safe and effective as other instrumentations being used for the surgical treatment of adolescent idiopathic scoliosis.

The influence of spine and trunk deformity on preoperative idiopathic scoliosis patients' health-related quality of life questionnaire responses.

Study Design. Retrospective case series. Objectives. To determine the influence of spine and trunk deformity on preoperative idiopathic scoliosis patients’ health-related quality of life questionnaire responses. Summary of Background Data. Management recommendations for patients with idiopathic scoliosis during adolescence are based heavily on spine deformity and to some extent trunk deformity magnitude. However, the manner in which these objective measures influence the patients’ perception of their condition is unclear. Methods. Of 67 consecutive preoperative patients, 61 (91%) had completed the Scoliosis Research Society-22 health-related quality of life questionnaire and had been studied with posterior exposure surface topography. Their average age was 15 years, 6 months (range 10 years, 10 months–20 years, 10 months), and the average maximum Cobb was 63° (range 40–137°). Correlations between spine and trunk deformity measures and Scoliosis Research Society-22 scores were determined by the Pearson correlation coefficient, with P < 0.01 considered significant. Results. For the study group, spine deformity (Cobb) correlated significantly only with Scoliosis Research Society-22 function (r = −0.39, P = 0.0022) domain. Neither coronal nor transverse plane trunk deformity composite scores correlated with any Scoliosis Research Society-22 scores. The Hump Index component of the transverse plane Suzuki Hump Sum composite score was the only trunk measurement to correlate significantly (function r = −0.45, P = 0.003; self image, r = −0.36, P = 0.0040). The strongest correlations occurred when the single thoracic curves, King classifications III and IV, were combined: Cobb versus function r = −0.53, P = 0.0027; Cobb versus self-image r = −0.46, P = 0.0099; and Hump Index versus function r = −0.60, P = 0.0005. There were no significant correlations between either spine deformity or any trunk deformity measure with Scoliosis Research Society-22 responses for either the double or thoracolumbar curve pattern groups. Conclusion. Both spine and upper thoracic transverse plane trunk deformity significantly influenced preoperative idiopathic scoliosis patients’ perception of function and self-image, but not pain or mental health. However, in spite of a fairly rigorous standard of proof, P ≤ 0.01, the significant r values ranged from −0.33 to −0.68, suggesting that there are factors other than spine and trunk deformity influencing the idiopathic scoliosis patients’ health-related quality of life questionnaire responses. Future studies are necessary to define these factors.

Scoliosis Correction Maintenance in Skeletally Immature Patients With Idiopathic Scoliosis: Is Anterior Fusion Really Necessary?

Study Design. A retrospective evaluation of the occurrence of the crankshaft phenomenon in skeletally immature patients with idiopathic scoliosis. Objective. To determine what factors, if any, contribute to a decreased occurrence of crankshaft phenomenon in patients treated with posterior surgery only. Summary of Background Data. Reports have described the progression of scoliotic deformity, termed the crankshaft phenomenon, in a region of solid posterior arthrodesis in skeletally immature patients. This has led some authors to advocate the use of concomitant anterior discectomy and fusion to prevent crankshaft. Methods. From 1989 through 1994, 18 Risser 0 patients with thoracic or thoracolumbar idiopathic scoliosis underwent Isola (De Puy-Acromed, Raynham, MA) posterior instrumentation and fusion. They were assessed for evidence of the crankshaft phenomenon, identified by coronal plane deformity progression of 10° or more, or a rib vertebra angle difference of 10° or more. The average age of the patients was 12.5 years (range, 10.5–15.5 years), and the average follow-up period was 39 months (range, 24–68 months). Results. Eleven patients (10 girls and 1 boy) had closed triradiate cartilage at the time of surgery. Their average Cobb angle was 62° before surgery, 21° after surgery, and 22° at follow-up assessment. No patients in this group met the criteria for crankshaft. Seven patients (6 girls and 1 boy) had open triradiate cartilage at the time of surgery. Their average Cobb angle was 62° before surgery, 18° after surgery, and 20° at follow-up evaluation. No patient had a 10° or more increase in rib vertebra angle difference. One patient had more than a 10° increase in her Cobb angle (11°) from postoperative to latest follow-up assessment. Her instrumentation construct, performed in 1989, used sublaminar wires as the caudal anchors. Hooks and pedicle screws are now used. Two of the seven patients with open triradiate cartilage underwent surgery during or before their peak height velocity and displayed no evidence of crankshaft. No deaths, neurologic complications, or infections occurred in either group. Conclusions. These findings suggest that scoliotic deformity progression can be prevented in skeletally immature patients with idiopathic scoliosis as young as 10 years of age with the use of stiff segmental posterior instrumentation, without the necessity of concomitant anterior arthrodesis.

The Prevalence of Increased Proximal Junctional Flexion Following Posterior Instrumentation and Arthrodesis for Adolescent Idiopathic Scoliosis

Study Design. Retrospective case series. Objective. To determine the prevalence of proximal junctional sagittal plane flexion increase after posterior instrumentation and arthrodesis. Summary of Background Data. Increased flexion proximal to the junction of the instrumented and fused spinal region with the adjacent mobile spine seems to be a relatively recent observation, may be increasing, and is occasionally problematic. Methods. The proximal junctional sagittal angulation 2 motion segments above the upper end instrumentation levels was measured on lateral standing preoperative and follow-up radiographs. Results. One hundred seventy-four of 208 consecutive patients (84%) at an average radiograph follow-up of 4.9 ± 2.73 years had increased proximal junctional flexion in 9.2%. The preoperative junctional measurements were normal for both normal and increased flexion groups. At follow-up, proximal junctional flexion had increased significantly more in the increased flexion group (2.1° vs. 14.1°, P < 0.0001). None of the possible risk factors studied, including demographic comparisons, Lenke classification (including lumbar and sagittal modifiers), end-instrumented vertebrae, end vertebra anchor configurations, surgical sequence, additional anterior surgery, rib osteotomies, and instrumentation length, were significantly associated with increased proximal junctional flexion at follow-up. Lenke 6 curves were at marginal risk of increased proximal junctional flexion (P = 0.0108). There were no differences between the groups in total Scoliosis Research Society-22r scores at an average follow-up of 8.0 ± 3.74 years. No patient had additional surgery related to increased proximal junctional flexion. Conclusion. The prevalence of increased proximal junctional flexion was 9.2%. No significant risk factors were identified. Total Scoliosis Research Society-22r scores were similar for groups with normal and increased proximal junctional flexion at follow-up.

The reliability and concurrent validity of the Scoliosis Research Society-22r patient questionnaire compared with the Child Health Questionnaire-CF87 patient questionnaire for adolescent spinal deformity.

Study Design. This is a clinic-based cross-sectional study involving 2 health-related quality-of-life (HRQL) questionnaires. Objectives. To compare the score distribution and reliability of the spinal deformity specific Scoliosis Research Society-22r (SRS-22r) questionnaire and the established generic Child Health Questionnaire-CF87 (CHQ-CF87), and to assess the concurrent validity of the SRS-22r using the CHQ-CF87 in an adolescent spine deformity population. Summary of Background Data. Different questionnaires are commonly thought to be necessary to assess the HRQL of adolescent and adult populations. But since spinal deformities usually begin in the second decade of life, longitudinal follow-up with the same HRQL is desirable. The SRS-22r HRQL has recently been validated for score distribution and internal consistency in a spinal deformity population ranging in age from 7 to 78 years. Methods. The SRS-22r and CHQ-CF87 HRQLs were completed by 70 orthopedic spinal deformity outpatients 8 to 18 years of age, of whom 54 returned mailed retest questionnaires at an average of 24 days later. Results. The ceiling effect averaged 27% for the SRS-22r and 36% for the CHQ-CF87. Respective values for internal consistency (Cronbach alpha) were 0.81 and 0.82, and for test-retest reproducibility the intraclass correlations (ICC) were 0.73 and 0.61. Concurrent validity was r ≥0.68 or more for relevant function, pain, and mental health domains. The SRS Self-Image and particularly the Satisfaction/Dissatisfaction with Management domains did not correlate well with any CHQ-CF87 domains (r = 0.50 and 0.30, respectively). Conclusion. In a spinal deformity population 8 to 18 years of age, the score distribution and reliability, internal consistency, and reproducibility of the SRS-22r were at least as good as the CHQ-CF87. The SRS-22r function, pain, and mental health domains were concurrently valid in comparison to relevant CHQ-CF87 domains, but the SRS-22r self-image and satisfaction/dissatisfaction domains were not, thereby providing health-related quality-of-life information not provided for by the CHQ-CF87.

Analysis of instrumentation/fusion survivorship without reoperation after primary posterior multiple anchor instrumentation and arthrodesis for idiopathic scoliosis

BACKGROUNDnDuring the past 25 years, spinal instrumentation systems and surgical techniques used to treat idiopathic scoliosis have evolved, achieving fewer patient restrictions during arthrodesis healing, shorter constructs, and better correction. The purposes of this retrospective comparative study were to determine the survivorship of the implant/fusion without reoperation and the risk factors influencing such survival.nnnMETHODSnFrom 1989 through 2002, 208 consecutive patients (index patient included, age 10-20 years) underwent primary posterior instrumentation and arthrodesis with the same multiple anchor implant system by one surgeon, a co-designer of the system. Two hundred seven were followed for more than 2 years; reoperation status was available for them at an average follow-up of 8.3 years. Twenty-one independent demographic, deformity, instrumentation, and process variables possibly influencing the need for reoperation were studied by comparing the reoperated group with the unreoperated group.nnnRESULTSnNineteen patients (9.2%) had reoperation; 16 (7.7%) were for indications related to posterior spine instrumentation. Survival of the implant/fusion without reoperation for spine instrumentation-related indications was 96% (95% confidence interval [CI], 93.2-98.7%) at 5 years, 91.6% (95% CI, 86.9-96.3%) at 10 years, 87.1% (95% CI, 79.5-94.6%) at 15 years, and 73.7% (95% CI, 48.6-98.6%) at 16 years, when the number at risk was nine. Reoperation need was significantly influenced by two implant variables: transverse connector design (p=.0012) and the lower instrumented vertebra anchors used (p=.0004). At 9 years, the longest interval allowing comparison, survival of the implant/fusion without reoperation for these two variables was 100% (six subjects at risk) compared to 82% (95% CI, 74.2-90.3%) with 59 patients still at risk for reoperation for those who did not have them, p=.0014.nnnCONCLUSIONSnThe most stable lower instrumented vertebra anchor configuration, bilateral pedicle screws, and the stronger transverse connector design, closed drop entry, provided the best survival of the implant/fusion without reoperation with this system and the techniques used at 9-year follow-up. We hope that this post-market study using survivorship techniques will be a guide for studies of other spinal implants.

The effect of arthrodesis, implant stiffness, and time on the canine lumbar spine.

Study Design Canine posterior lumbar instrumentation and fusion. Objectives To study effects of implant rod size and time on the stiffness of related spine construct elements. Summary of Background Data The ideal stiffness of posterior spinal implants to successfully treat clinical instability or deformity with minimal side effects is unknown. Methods Twenty-six canines were divided into 7 groups: control, and 6 or 12-month survival after sham or lumbar L3-5 arthrodesis (facet, posterior, and posterolateral) with either 4.76 or 6.35u2009mm diameter rod-pedicle screw instrumentation. Axial flexion-compression stiffness of the L3-5 segment components and axial compression stiffness of the bypassed and adjacent anterior column elements were measured. Results Posterior instrumentation initially increased flexion-compression stiffness of the L3-5 segment more than the intrinsic stiffness of the implant due to control of spinal column flexion buckling. Sham operation did likewise, apparently by posterior scar tissue tethering. The percent contribution of the implant construct to instrumented segment stiffness was significantly less at 6 months without further change from 6 to 12 months; 14% and 22% for 4.76 and 6.35u2009mm rod constructs, respectively. Spinal column as well as posterior column stiffness after fusion was independent of rod size at 6 months and increased at 12 months in only the 4.76u2009mm rod group. Bypassed L4 vertebral body stiffness decreased significantly at 6 months, was not rod size dependent and changed little between 6 and 12 months. Bypassed disk stiffness responded in a biphasic manner, apparently increasing at 6 months with significant decrease from 6 to 12 months. Adjacent disk compression stiffness progressively decreased over time independent of rod size, also decreasing after sham operation. Conclusions Both rod sizes were associated with 100% fusion and produced similar changes in bypassed bone and disks, and adjacent disks. There was delayed fusion stress shielding by 6.35u2009mm rod constructs.