Factor analysis of the SRS-22 outcome assessment instrument in patients with adult spinal deformity.

PURPOSE: Designed for patients with adolescent idiopathic scoliosis, the SRS-22 is now widely used as an outcome instrument in patients with adult spinal deformity (ASD). No studies have confirmed the four-factor structure (pain, function, self-image, mental health) of the SRS-22 in ASD and under different contexts. Factorial invariance of an instrument over time and in different languages is essential to allow for precise interpretations of treatment success and comparisons across studies. This study sought to evaluate the invariance of the SRS-22 structure across different languages and sub-groups of ASD patients. METHODS: Confirmatory factor analysis was performed on the 20 non-management items of the SRS-22 with data from 245 American English-, 428 Spanish-, 229 Turkish-, 95 French-, and 195 German-speaking patients. Item loading invariance was compared across languages, age groups, etiologies, treatment groups, and assessment times. A separate sample of SRS-22 data from 772 American surgical patients with ASD was used for cross-validation. RESULTS: The factor structure fitted significantly better to the proposed four-factor solution than to a unifactorial solution. However, items 14 (personal relationships), 15 (financial difficulties), and 17 (days off work) consistently showed weak item loading within their factors across all language versions and in both baseline and follow-up datasets. A trimmed SRS (16 non-management items) that used the four least problematic items in each of the four domains yielded better-fitting models across all languages, but equivalence was still not reached. With this shorter version there was equivalence of item loading with respect to treatment (surgery vs conservative), time of assessment (baseline vs 12 months follow-up), and etiology (degenerative vs idiopathic), but not age (< vs ≥50 years). All findings were confirmed in the cross-validation sample. CONCLUSION: We recommend removal of the worst-fitting items from each of the four domains of the SRS-instrument (items 3, 14, 15, 17), together with adaptation and standardization of other items across language versions, to provide an improved version of the instrument with just 16 non-management items.

Complications and predictive factors for the successful treatment of flatback deformity (fixed sagittal imbalance).

STUDY DESIGN: This is an analysis of consecutive cases of flatback deformity (fixed sagittal imbalance), treated by one of two surgeons at a university hospital. OBJECTIVE: To define factors that contribute to results with treatment of flatback syndrome, classify types of sagittal deformities, and discuss complications. SUMMARY OF BACKGROUND DATA: There are few reports that detail the results and complications of current instrumentation and osteotomy techniques for correction of fixed sagittal deformities. METHODS: Twenty-eight patients treated with osteotomies for sagittal imbalance were eligible for 2-year minimum follow-up (average, 3.6 years). Patients were classified (segmental imbalance, Type 1; or global imbalance, Type 2) and evaluated by upright radiographs, chart review, and a questionnaire. RESULTS: Twenty-eight (100%) patients returned the questionnaire, and 28 had current radiographs. Five treatment groups were evaluated based on osteotomy type (anterior, posterior [Smith-Petersen], both, or pedicle subtraction) and use of anterior structural grafting. All patients were treated with modern bilateral hook-rod-screw constructs. Mean correction at the osteotomy levels was 25 degrees for Type 1 deformities and 30 degrees for Type 2 (P < 0.05). Sagittal correction averaged 6.6 cm in Type 2 deformities (P < 0.05). Questionnaire analysis showed a significant and persistent reduction in subjective pain level. There were seven patients with 11 total complications and no neurologic deficits. Associations among patients who were not satisfied with their results (n = 4) included insufficient sagittal correction (P = 0.045), pseudarthrosis (P = 0.045), coronal imbalance, and four or more medical comorbidities (P = 0.03). CONCLUSIONS: Satisfaction with the results of treatment may be reduced in patients with four or more major co-existent medical problems, insufficient sagittal correction, and resultant pseudarthrosis.

Minimum 5-year results of degenerative spondylolisthesis treated with decompression and instrumented posterior fusion.

STUDY DESIGN: An analysis of consecutive cases of degenerative spondylolisthesis treated by one of two surgeons at a university hospital. OBJECTIVES: To assess at a minimum 5-year follow-up the complication rate, reoperation rate, radiographic results, and patient satisfaction with surgical treatment of lumbar degenerative spondylolisthesis by means of segmental posterior instrumented fusion with decompression. SUMMARY OF BACKGROUND DATA: No reports of minimum 5-year follow-up for surgical treatment of degenerative spondylolisthesis were found in the literature. METHODS: The potential study population consisted of 49 consecutive patients who had undergone no prior surgery for degenerative spondylolisthesis (average age, 66.7 years; range, 52.2-78.7 years) with mean follow-up of 6.5 years (range, 5-10.75 years) who were treated with decompression, autogenous iliac crest bone grafting, intertransverse process fusion, and segmental (pedicle screw) instrumentation. Eight patients had died; the remaining 41 were included in the study sample. Thirty-six (88%) of the 41 patients returned an outcome questionnaire and had current radiographs. RESULTS: There was one case of instrument failure (one broken screw with late fusion), and one superficial infection. There were no neurologic deficits, no pseudarthroses, no recurrent stenosis at the fused segment, and no progression of deformity at the fused level. Five patients had symptomatic adjacent level transition syndromes. There were seven additional currently asymptomatic radiographic transition syndromes. Segmental sagittal Cobb angles were maintained at the fused level (17.7 +/- 8-18.8 +/- 7 degrees). Eighty-three percent reported satisfaction with the procedure, 86% thought their back and leg pain was still significantly better than before surgery, and 77% would have the procedure again if needed. Poor satisfaction (n = 4) was associated with more than four medical comorbidities (P < 0.03). A significant number (12 of 49, 24%) of patients had died or were ill more than 5 years after surgery. CONCLUSIONS: Radiographic transition syndromes were common. Major complications (2%), implant failures (2%), and symptomatic pseudarthroses (0%) were low.