Analysis of the reliability of surgeons' ability to differentiate between idiopathic and degenerative spinal deformity in adults radiologically. What descriptive parameters help them decide?

PURPOSE: Adult spinal deformity (ASD) may be classified as idiopathic (ID) or degenerative (DD) (or other) based on classifier's perception, the reliability of and factors inherent to which remain unknown. The aim of this study is to evaluate the inter- and intra-observer reliability of surgeons' perception in differentiating ID from DD and to identify the determinants of this differentiation. METHODS: From a multicentric prospective database of ASD, 179 patients were identified with the diagnosis of ID (n = 103) or DD (n = 76); without previous surgery; and a lumbar coronal curve larger than 20°. Standing antero-posterior and lateral X-rays of these patients were sent to five experienced spine surgeons to be identified as DD or ID (or other); followed by a second round after reshuffling. Weighted kappa statistics were used, the strength of agreement for the kappa coefficient was considered as; 0.81-1 = almost perfect, 0.61-0.8 = substantial, 0.41-0.60 = moderate, 0.21-0.40 = fair, 0.01-0.20 = slight, and ≤0 = poor. Patients were then stratified based on the number of agreements on a total of 10 rounds as excellent (10 out of 10), good (more than 7 out of 10) and fair/poor (7 and less). These excellent and good agreements were further compared for additional radiological parameters. RESULTS: Agreement levels were moderate to substantial for intra but mostly fair for inter-observer comparisons. For ID patients, there were 42 cases with excellent and 38 with very good agreement whereas for DD, there were no excellent and only 17 cases with very good agreement. Upon comparison of these (ID vs DD for at least very good cases), it was seen that they were different for some coronal parameters such as lumbar Cobb angle (larger in ID, p < 0.001), central sacral vertical line (CSVL) modifier (C more common in ID, p = 0.007) and presence of rotatory subluxation (less common in DD, p = 0.017), but very different for sagittal parameters (lumbar lordosis, sagittal vertical axis, T2 sagittal tilt, pelvic tilt, sacral slope, and global tilt; increased sagittal imbalance in DD, all p ≤ 0.001). CONCLUSION: Surgeons in this study demonstrated reasonable (moderate to substantial) intra-observer agreement, but only fair agreement amongst them. Alarming as it may appear, we should be cautious in interpreting these results based on only radiology and no clinical information. In patients with good agreement, the most consistent radiologic determinant of degenerative ASD appeared to be the presence of sagittal imbalance.

Multiple Regression Analysis of Factors Affecting Health-Related Quality of Life in Adult Spinal Deformity.

BACKGROUND: Previous studies demonstrated the adult spinal deformity (ASD) population is heterogeneous. Multiple parameters may affect health-related quality of life (HRQL). AIM: To understand the ranking of parameters affecting HRQL in ASD using multiple regression analysis. PATIENTS AND METHODS: A total of 483 patients enrolled in a prospective multicenter ASD database from the population. Multiple regression analysis was performed for Scoliosis Research Society-22 (SRS-22) and Oswestry Disability Index (ODI) separately. Initially proposed primary variables of diagnosis (highest correlation), age, lordosis gap (L gap), and coronal curve location were regressed for each response variable (SRS-22 and ODI) univariately. Age and L gap could not be used together because of high colinearity. Coronal curve location was removed owing to an insignificant correlation. Two initial models were considered per response, consisting of diagnosis and age in one and diagnosis and L gap in the other. The rest of the potentially predictive variables were introduced in these models one at a time. Final models were evaluated using stepwise automatic model selection. RESULTS: For ODI, body mass index (BMI), gender, and sagittal and spinopelvic parameters were in the basic model but only BMI and gender in the model with L gap and only gender in the model with age were highly predictive. For SRS-22, a large number of parameters were in the basic model but BMI, gender, coronal balance, lordosis curve, and sagittal vertical axis in the model with L gap and only gender in the model with age were highly predictive. Coronal curve location was not significantly predictive in any model. CONCLUSIONS: These findings reiterate the importance of patient diagnosis, age, and/or the amount of lordosis as the most important factors affecting HRQL in ASD. Gender, BMI, and sagittal vertical axis appear to be consistently important co-variables whereas coronal balance and magnitude of L curves may also be important in SRS-22. These may aid in better understanding the problem in ASD and may be useful in future classifications.

The reliability of sagittal pelvic parameters: the effect of lumbosacral instrumentation and measurement experience.

STUDY DESIGN: Sagittal pelvic parameters (SPPs) of a representative patient sample drawn from a consecutive adult spinal deformity database were measured using Surgimap Spine. Estimated coefficient of reliability intraclass coefficient (95% confidence interval), standard error of measurement, and mean absolute deviation were used for the analysis. OBJECTIVE: The primary objective of this study was to assess the reliability of SPP measurements using Surgimap Spine. The secondary objective was to evaluate the impact of pelvic instrumentation as well as the impact of user expertise. SUMMARY OF BACKGROUND DATA: The radiographical measurement of SPP is increasingly recognized as playing a critical role in establishing the surgical goals and surgical strategy of many spinal disorders. Although instrumented flatback is a common cause of sagittal malalignment, to our knowledge, SPP measurement reliability has never been assessed in instrumented spines. METHODS: Sixty-three adult full-spine standing lateral radiographs (31 with lumbosacral instrumentation) were measured twice by 13 observers using Surgimap Spine. Observers were stratified into 3 levels of experience: high (research coordinators, 4), mid (senior surgeons, 5), and low (junior surgeons, 4). Research coordinators trained all surgeons for less than 30 minutes. Parameters measured were pelvic incidence, pelvic tilt, and sacral slope. RESULTS: Thirteen observers and 63 radiographs generated 817 observations (2 misses). Overall inter- and intraobserver reliability of SPP measurement was excellent (intraclass coefficient > 0.85). Lumbosacral instrumentation did not modify intraobserver reliability but reduced significantly interobserver reliability of pelvic tilt (P = 0.006) and sacral slope (P = 0.007). Experience did not affect intraobserver reliability but interobserver reliability of highly experienced observers was significantly lower (P < 0.05) than among less experienced observers. CONCLUSION: Measurement of SPP using Surgimap Spine equals or improves previously reported reliability data. Lumbosacral instrumentation reduces interobserver reliability taking it from excellent to moderate in the sacral slope measurement. Inexperienced observers can measure SPP reliably after a short tutorial. LEVEL OF EVIDENCE: 4.