Thomas R. Haher

Results of the Scoliosis Research Society instrument for evaluation of surgical outcome in adolescent idiopathic scoliosis. A multicenter study of 244 patients.

STUDY DESIGN An outcome questionnaire was constructed to evaluate patient satisfaction and performance and to discriminate among patients with adolescent idiopathic scoliosis. OBJECTIVES To determine reliability and validity in a new quality-of-life instrument for measuring progress among scoliosis patients. SUMMARY OF BACKGROUND DATA Meta-analysis of the surgical treatment of adolescent idiopathic scoliosis determined that a uniform assessment of outcome did not exist. In addition, patient measures of well-being as opposed to process measures (e.g., radiographs) were not consistently reported. This established the need for a standardized questionnaire to assess patient measures in conjunction with process measures. METHODS The instrument consists of 24 questions divided into seven equally weighted domains as determined by factor analysis: pain, general self-image, postoperative self-image, general function, overall level of activity, postoperative function, and satisfaction. The questionnaire takes approximately 5 minutes to complete and is taken at predetermined time intervals. A total of 244 of patients from three different sites responded to the questionnaire. RESULTS The reliability based on internal consistency was confirmed with a Cronbachs alpha coefficient greater than 0.6 for each domain. In addition, acceptable correlation coefficient values greater than 0.68 were obtained for each domain by the test-retest method on normal controls. Similarly; to establish validity of the questionnaire, responses of normal high school students were compared with that of the patients. Consistent differences were noted in the domains between the two groups with P < 0.003. The largest differences were in pain (control, 29.96 +/- 0.20; patient, 13.23 +/- 5.55) and general level of activity (control, 14.96 +/- 0.20; patient, 12.16 +/- 3.23). Examination of the relationship between the domains and patient satisfaction showed that pain correlates with satisfaction to the greatest degree (Pearsons correlation co-efficient, r = -0.511; P < 0.001), followed by self-image (r = 0.412; P < 0.001). CONCLUSIONS This questionnaire addresses patient measures for evaluation of outcome in adolescent idiopathic scoliosis surgery by examining several domains. It also allows for dynamic monitoring of scoliosis patients as they become adults. This is a validated instrument with good reliability measures.

A Multicenter Study of the Outcomes of the Surgical Treatment Of Adolescent Idiopathic Scoliosis Using the Scoliosis Research Society (SRS) Outcome Instrument

Study Design. A multicenter study of the outcomes of the surgical treatment of adolescent idiopathic scoliosis using the Scoliosis Research Society Questionnaire (SRS 24). Objective. To evaluate the patient based outcome of the surgical treatment of adolescent idiopathic scoliosis. Summary of Background Data. A paucity of information exists with respect to patient measures of outcome regarding the surgical treatment of adolescent idiopathic scoliosis. To our knowledge, no prospective outcome study on this topic thus far exists. Methods. Using the SRS 24 questionnaire, seven scoliosis centers agreed to prospectively assess outcome for surgically treated patients with adolescent idiopathic scoliosis. Data were collected before surgery and at 24 months after surgery. Data were analyzed using paired and independent samples t test for all seven SRS 24 questionnaire domains (Pain, General Self-Image, Postoperative Self-Image, Postoperative Function, Function From Back Condition, General Level of Activity, and Satisfaction) using Statistical Package for Social Science. The domains were analyzed with respect to the total cohort, gender, curve magnitude, and type of surgery using independent-samples t tests. Results. A total of 242 patients were included in our analysis. A baseline preoperative pain level of 3.68 of 5 was found. This improved to 4.63 after surgery, representing an improvement of 0.95 points. Surgical intervention was associated with improving outcome when compared with preoperative status. Pain, General Self-Image, Function From Back Condition, and Level of Activity all demonstrated statistically significant improvement as compared with preoperative status (P < 0. 001). Overall, patients were highly satisfied with the results of surgery. Conclusion. Preoperative pain exists in our adolescent scoliosis population. Pain scores were improved in our study population at the 2-year postsurgical follow-up. Statistically significant improvements were likewise seen in the General Self-Image, Function From Back Condition, and Level of Activity domains. The present study demonstrates the ability of surgery to improve the outcome of patients afflicted with adolescent idiopathic scoliosis.

The role of the lumbar facet joints in spinal stability. Identification of alternative paths of loading.

Study Design The role of the facet joints in spinal stability was analyzed using long-segment cadaver spines. Objectives To establish the existence of alternate paths of loading when the facet joints and anulus are compromised. Summary of Background Data It has been reported that facet arthrosis and degeneration never occur without the presence of adjacent disc degeneration. This suggests that intact discs protect the facets from severe loading and degeneration. Based on these studies of spinal mechanics, the authors devised an experiment to further explain the relationship of the disc and the facet in sharing compressive loads. Methods Ten human cadaver spines were placed unsupported in an Instron Model 4206 Tensile Testing Machine. Compressive loads of 1000 N then were applied to the specimens at a rate of 20 N per minute. The facet joints, anterior anulus, and lateral anulus then were destroyed sequentially at L3 and the loading cycles were repeated. The load-deflection curves for each cycle were evaluated and compared with the intact specimen. Results Unilateral and bilateral facetectomies had little affect on the ability of the specimen to support a physiologic load. Facetectomies in combination with anterior anulus destruction showed a significant change in the ability of the specimen to support a load with an extension moment applied. Conclusions The facet joints of the lumbar spine are not the principle support structures in extension. With destruction of the facets, an alternate path of loading is established. The alternate path of loading transfers axial loads to the anulus and anterior longitudinal ligament to support the spine. Although facet joint destruction will not produce acute instability, it will transfer the loads to the adjacent disc and conceivably accelerate its degeneration.

Curve prevalence of a new classification of operative adolescent idiopathic scoliosis: does classification correlate with treatment?

Study Design. A retrospective multicenter consecutive case review of operative adolescent idiopathic scoliosis. Objectives. To define the curve prevalence of a large consecutive series of cases with operative adolescent idiopathic scoliosis as classified by a new system and to test the ability of this new classification system to correlate with regions of the scoliotic spine to be instrumented/fused. Summary of Background Data. A new comprehensive, two-dimensional classification system, intended to be treatment based, has been developed. However, it has not been tested whether all presenting operative cases of adolescent idiopathic scoliosis are classifiable in a large consecutive series, nor has the prevalence of specific curve types been determined. In addition, it is unknown whether this classification is truly treatment based, as to whether it can correlate with regions of the spine to be instrumented/fused. Methods. A multicenter retrospective review of 606 consecutive operative cases of adolescent idiopathic scoliosis was performed. All cases were classified by a new triad classification system, which included the following: a curve type (1–6), a lumbar spine modifier (A, B, C), and a sagittal thoracic modifier (−, N, +). Prevalence of the individual three components of the system and the classification grouping of all three components together were performed. In addition, the authors assessed whether this system could correlate with regions of the spine that should be included in the instrumentation and fusion, based on exactly which regions were fused during the operative procedure. Results. All 606 cases were classifiable by this system. Prevalence of the six curve types noted was as follows: Type 1, main thoracic (n = 305, 51%); Type 2, double thoracic (n = 118, 20%); Type 3, double major (n = 69, 11%); Type 4, triple major (n = 19, 3%); Type 5, thoracolumbar/lumbar (n = 74, 12%); and Type 6, thoracolumbar/lumbar–main thoracic (n = 17, 3%). The five most common curve classifications noted were as follows: 1AN, 1BN, 2AN, 5CN, and 1CN, which accounted for 58% of all curve classifications noted. An average of 90% of the operative cases had surgically structural regions of the spine included in the instrumentation and fusion as predicted by the curve type. Conclusions. A new comprehensive classification system for operative adolescent idiopathic scoliosis found all 606 consecutive cases of adolescent idiopathic scoliosis classifiable, with the Type 1, main thoracic curve pattern, the most common curve type found (51%). This new classification system appears to correlate with treatment of surgically structural regions of the spine fused in 90% of cases by the objective radiographic criteria used.

Multisurgeon Assessment of Surgical Decision-Making in Adolescent Idiopathic Scoliosis : Curve Classification, Operative Approach, and Fusion Levels

Study Design. A multisurgeon assessment of curve classification, selection of operative approach, and fusion levels via a case study presentation. Objectives. To evaluate the ability of a group of scoliosis surgeons, not involved in the development of a new classification system, to accurately choose the corresponding curve classification of adolescent idiopathic scoliosis (AIS) cases and to evaluate the variability in the selection of operative approaches and both proximal and distal fusion levels in accordance with the new classification system in operative adolescent idiopathic scoliosis. Summary of Background Data. Recent evaluations using the King method for classifying AIS has shown poor intraobserver and interobserver reliability. A new, comprehensive classification system of AIS has been developed, but the result of a scoliosis surgeon’s ability to apply the objective classification is unknown. In the surgical treatment of AIS, there are three choices for the operative approach (anterior, posterior, or both) and multiple choices for the selection of fusion levels. Methods. During an AIS roundtable discussion at a spinal surgery meeting, 28 scoliosis surgeons were presented seven cases of operative AIS via good quality slides. Standard preoperative radiographs and clinical photographs were presented, and the reviewers were asked to classify the cases by a new classification system, choose their preferred surgical approach, and classify both proximal and distal fusion levels. Results. For the seven cases presented, 84% of the curve types, 86% of lumbar modifiers, and 90% of sagittal thoracic modifiers were classified by the reviewers as described in the new classification. The case study found widely variable operative approaches and fusion levels chosen by the reviewers. There was an average of five different proximal (range, 4–8) and four different distal (range, 3–5) fusion levels chosen by the reviewers for each case. Conclusions. This case study assessment found a relatively high rate (84–90%) of agreement in curve classification of the individual components of a new classification system of AIS. This suggests the ability of a group of scoliosis surgeons to identify the specific criteria necessary for this new classification system of AIS. In addition, the high variability in selection of both operative approach and fusion levels confirms the current lack of standardized treatment paradigms. This further reinforces the need for a method to critically and objectively evaluate these variable treatments to determine the “best” radiographic and clinical results.

Occipital screw pullout strength. A biomechanical investigation of occipital morphology.

STUDY DESIGN A three-group design with consistent pullout strength measures. OBJECTIVES To determine pullout strength of three fixation types (unicortical screws, bicortical screws, wires) and to investigate their correlation with respect to occipital morphology. SUMMARY OF BACKGROUND DATA A secured, multidirectional occipitocervical fusion requires internal fixation. Devices secured at occipital protuberance were suggested to offer the greatest pullout strength because of this regions thickness. METHODS Twelve fresh human cadaveric occiputs were sketched with a grid delineating 21 fixation sites. Each site was drilled and hand-tapped. Four specimens were instrumented with unicortical screws on one side of the midline and bicortical screws on the other. Another four were instrumented with bicortical screws and wires, and the remaining four were instrumented with unicortical screws and wires. Two points on each specimen were secured with identical fixation to examine side-to-side symmetry. An MTS materials testing apparatus (MTS Systems Corporation, Eden Prairie, MN) was used to displace the fixators. Pullout strengths at different anatomic locations were recorded. RESULTS The greatest pullout strength was at the occipital protuberance for all fixation types. The bicortical pullout strength was 50% greater than unicortical. The wire pullout strength was not significantly different from that of the unicortical screw (P > 0.05). Seventy-eight percent of wires broke at 1100 N. Unicortical pullout strength at occipital protuberance was comparable with that of the bicortical screw at other locations. CONCLUSIONS Unicortical screw fixation at occipital protuberance offers acceptable pullout strength without the potential complications of bicortical screws or wire fixation.

Meta-analysis of surgical outcome in adolescent idiopathic scoliosis : a 35-year English literature review of 11,000 patients

Study Design Meta-analysis of the English literature on the surgical treatment of adolescent diopathic scoliosls. Objective To gather comparable data from a number of different soureces and combine the data to create a larger, more statistically significant pool of information for the analysis of surgical outcome. Summary of Background Data Meta-analysis is a techinique of scientific literature review used in outcome evaluation of medical treatment. This technique has been applied to the surgical outcome of adolescent idiopathic scoliosis. Methods A structured literature review was performed that cross-referenced English literature articles pertaining to the surgical treatment of adolescent idlopathic scoliosis with a focus on patient-based outcomes. Measures of patient satisfaction were compared with process measures of care. Results A number of patients (10,989) were reviewed in 139 patient populations. Unspecified curve types (9424) and King curve types (1565) were reviewed over a 35-year period from 1958 to 1993. Of the patients, 87.32% were studied retrospectively and 12.70% prospectively, Effect-weighted follow-up was 6.8 years. Only studies with complete process and patient data for unspecified or king curve types were included for satisfaction correlation calculations. Pearson product moment correction calculations. Pearson product moment correlation for n = 33 studies, n = 2926 patients revealed a positive r =0.628 correlation between degree of curve correction and percent statisfaction per study. To determine the degree of curvature correction resulting in patient satisfaction a stepwise multiple linear regression analysis was performed with level of confldence (P = 0.05). Of significance was that the degree of cuvature corrected accounted for all the satisfaction variance predicted. A significant correction and percent of patients satisfied. The percent of correction and the Group type (either unspecified or King classified), did not significantly alter this prediction. The best predictor of satisfaction appears to be degree of curve correction according to these data. Conclusion Patients appear to be more satisfied by the magnitude of curve correction rather than the percent of curve correction. The degree of curvature before surgery did not predict patient satisfaction. Pearsons r = 0.045. Satisfaction appears to be best predicted by the degree of correction only and not by the percent curve correction, the curve magnitude before surgery, nor the Group type (King, unspecified). Patient satisfaction is subjective. It does not reflect the benefits of surgery with respect to the future preservation of pulmonary function in thoracic curves nor the prevention of osteoarthristis in lumbar curves.

Factors involved in the decision to perform a selective versus nonselective fusion of Lenke 1B and 1C (King-Moe II) curves in adolescent idiopathic scoliosis.

Study Design. A retrospective evaluation of 203 adolescent idiopathic scoliosis patients with Lenke 1B or 1C (King-Moe II) type curves. Objectives. To evaluate the incidence of inclusion of the lumbar curve in the treatment of this type of deformity as well as radiographic factors associated with lumbar curve fusion. Summary of Background Data. In patients with structural thoracic curves and compensatory lumbar curves, many authors have recommended fusing only the thoracic curve (selective thoracic fusion). Studies have shown that correction of the thoracic curve results in spontaneous correction of the unfused lumbar curve; however, in some cases, truncal decompensation develops. Though there have been various attempts to define more accurately what type of curve pattern should undergo selective fusion, controversy continues in this area. Methods. Measurements were obtained from the preoperative standing posteroanterior and side-bending radiographs of 203 patients with Lenke Type 1B or 1C curves from five sites of the DePuy AcroMed Harms Study Group. Patients were divided into two groups depending on their most distal vertebra instrumented: the “selective thoracic fusion” group included patients who were fused to L1 or above and the “nonselective fusion” group included patients fused to L2 or below. A statistical comparison was conducted to identify variables associated with the choice for a nonselective fusion. Results. The incidence of fusion of the lumbar curve ranged from 6% to 33% at the different patient care sites. Factors associated with nonselective fusion included larger preoperative lumbar curve magnitude (42 ± 10°vs. 37 ± 7°, P < 0.01), greater displacement of the lumbar apical vertebra from the central sacral vertical line, (3.1 ± 1.4 cm vs. 2.2 ± 0.8 cm, P < 0.01), and a smaller thoracic to lumbar curve magnitude ratio (1.31 ± 0.29 vs. 1.44 ± 0.30, P = 0.01). Conclusions. The characteristics of the compensatory “nonstructural” lumbar curve played a significant role in the surgical decision-making process and varied substantially among members of the study group. Side-bending correction of the lumbar curve to <25° (defining these as Lenke 1, nonstructural lumbar curves) was not sufficientcriteria to perform a selective fusion in some of these cases. The substantial variation in the frequency of fusing the lumbar curve (6% to 33%) confirms that controversy remains about when surgeons feel the lumbar curve can be spared in Lenke 1B and 1C curves. Site-specific analysis revealed that the radiographic features significantly associated with a selective fusion varied according to the site at which the patient was treated. The rate of selective fusion was 92% for the 1B type curves compared to 68% for the 1C curves.

A multicenter Study analyzing the relationship of a standardized radiographic scoring system of adolescent idiopathic Scoliosis and the Scoliosis Research Society outcomes instrument

Study Design. A multicenter study examining the association between radiographic and outcomes measures in adolescent idiopathic scoliosis. Objectives. To evaluate the association between an objective radiographic scoring system and patient quality of life measures as determined by the Scoliosis Research Society outcomes instrument. Summary of Background Data. Although surgical correction of scoliosis has been reported to be positively correlated with patient outcomes, studies to date have been unable to demonstrate an association between radiographic measures of deformity and outcomes measures in patients with adolescent idiopathic scoliosis. Methods. A standardized radiographic deformity scoring system and the Scoliosis Research Society outcome tool were used prospectively in seven scoliosis centers to collect data on patients with adolescent idiopathic scoliosis. A total of 354 data points for 265 patients consisting of those with nonoperative or preoperative curves ≥10°, as well as those with surgically treated curves, were analyzed. Correlation analysis was performed to identify significant relationships between any of the radiographic measures, the Harms Study Group radiographic deformity scores (total, sagittal, coronal), and the seven Scoliosis Research Society outcome domains (Total Pain, General Self-Image, General Function, Activity, Postoperative Self-Image, Postoperative Function, and Satisfaction) as well as Scoliosis Research Society outcomes instrument total scores. Radiographic measures that were identified as significantly correlated with Scoliosis Research Society outcome scores were then entered into a stepwise regression analysis. Results. The coronal measures of thoracic curve and lumbar curve magnitude were found to be significantly correlated with the Total Pain, General Self-Image, and total Scoliosis Research Society scores (P < 0.0001). The thoracic and upper thoracic curve magnitudes were also correlated with General Function (P < 0.002). The “coronal” subscore as well as the “total” score of the Harms Study Group radiographic scoring system were also significantly correlated with these Scoliosis Research Society domain and total scores. No radiographic measures taken after surgery were significantly correlated with the postoperative domains of the Scoliosis Research Society outcomes instrument. Stepwise regression analysis of these radiographic measures as predictors of Scoliosis Research Society scores resulted in adjusted R2 values of 0.03–0.07 (P < 0.0001). Although these results show that a significant association exists between the radiographic Cobb angle measure of the scoliosis and the Scoliosis Research Society outcomes scores, the low R2 values indicate that variables other than the radiographic appearance of the deformity (e.g., psychosocial, functional) must also be affecting these scores. Conclusion. The Cobb angle measure of the major deformity has a small, but statistically significant, correlation with the reported Total Pain, General Self-Image, and General Function as measured by the Scoliosis Research Society outcomes instrument. None of the radiographic measures in this population correlated with postoperative domain scores of the Scoliosis Research Society outcomes tool.

Instantaneous Axis of Rotation as a Function of the Three Columns of the Spine

A knowledge of the rotatory motion of the vertebral bodies is needed to understand the normal biomechanical behavior of the spine. The aims of this investigation were 1) to define the instantaneous axis of rotation of the lumbar spine in rotation; and 2) to study the effect of the loss of the anulus, facet joints, and ligamentous structures on the location of the instantaneous axis of rotation. The instantaneous axis of rotation. The instantaneous axis of rotation was found in 10 human cadaver thoracolumbar spines by the method of Reuleaux from superimposed serial photographs. Long-segment specimens were tested to minimize the effect of the imposed axis of the testing device. The instantaneous axis of rotation was consistently posterior to the anulus in the intact spine. With isolated destruction of the columns of the spine, the instantaneous axis of rotation migrated to the remaining intact structures. Anterior releases enhance derotation by removing the primary rotatory stabilizer. Ultimate control of a rotatory deformity or instability lies in the recognition that the anterior structures have a mechanical advantage in resisting torsion.