Index radiographic measurements in the prediction of progression in infantile idiopathic scoliosis: a comparative analysis and description of a novel predictive model.

PURPOSE: To assess the comparative accuracy of commonly utilised index radiological measurements in the prognosis of infantile idiopathic scoliosis (IIS) and build a parsimonious prognostic model utilising these measurements. METHODS: This was a retrospective analysis of a UK population of patients with IIS. Index radiological parameters were analysed, and outcome of their condition was determined over long-term follow-up. Comparative accuracy of each radiological measurement category was determined by logistic regression analyses and the corresponding receiver operating characteristic (ROC) curve. A predictive model of IIS progression using these measurements was then created. RESULTS: All three radiological measurement categories were predictive of IIS progression. However, on pairwise comparison of ROC curves and multivariate analysis, the index Cobb angle proved the most significant predictor of curve progression. Using the index Cobb angle only, a predictive model of curve progression achieved an accuracy of 81.18% with a cut-off Cobb angle of 34.5° found to be the optimal threshold to discriminate a progressive from resolving curve. CONCLUSION: Of the three analysed index radiological parameters commonly used by surgeons in the prognosis of IIS, we found that the Cobb angle is the most accurate predictive measure. Further, neither addition of the RVAD nor convex RVA provided significant further prognostic value in a multivariate model of progression. However, not even the Cobb angle model was accurate in all cases; emphasising caution should be applied when relying on index radiological measurements to predict IIS outcomes.

Long-term follow-up of patients with infantile idiopathic scoliosis: is the rib vertebra angle difference (RVAD) a reliable indicator of evolution?

PURPOSE: Since its original description by Mehta, the rib vertebra angle difference (RVAD) and, in particular, a threshold of 20° have become an accepted and widely utilised prognostic indicator in the assessment of patients presenting with an infantile idiopathic scoliosis (IIS). However, uncertainty in the utility of the RVAD in the prognosis of IIS remains. The aims of this study were to investigate the prognostic significance of the RVAD and to describe the changes in RVAD over long-term follow-up of patients with progressive and resolving IIS. METHODS: This was a retrospective analysis of patients presenting with IIS at a tertiary spinal deformity unit in the UK. Serial patient radiographs were reviewed and a logistic regression model using the patients index RVAD was created to predict the likelihood of curve progression. RESULTS: At both index presentation and over long-term follow-up, patients with a progressive curve had significantly greater mean Cobb angle and RVAD measurements than those with resolving curves. The RVAD and Cobb were found to correlate positively in both groups, reflecting the underlying costovertebral pathoanatomy. The logistic regression model demonstrated that the optimal RVAD threshold in predicting IIS progression was lower at 17.1° than the 20° cut-off previously advocated. CONCLUSION: This study describes the utility of the RVAD in predicting IIS evolution. From this analysis, we would advise caution in predicting outcomes based on the index RVAD at presentation. LEVEL OF EVIDENCE: II.

Counting the Cost of Failed Spinal Fusion for Relief of Low Back Pain: Does Primary Fusion With Bone Morphogenetic Protein Make Economic Sense From a Primary Payer Perspective?

STUDY DESIGN: A retrospective cohort study. OBJECTIVES: To investigate the unknown direct costs of failed instrumented lumbar fusion using iliac crest bone graft (ICBG) and subsequent reoperation utilizing recombinant human bone morphogenetic protein-2 (rhBMP-2) from a primary payer perspective. SUMMARY OF BACKGROUND DATA: Recent evidence has demonstrated increased rates of instrumented lumbar fusion and utilization of rhBMP-2 to treat a range of conditions causing lower back pain. For health care providers with finite financial resources, there is an increasing demand to evaluate economic costs of available treatment modalities. The high cost of rhBMP-2 has often been cited as a leading reason for delaying its universal acceptance as a preferred substitute to ICBG. It has been hypothesized that rhBMP-2 may demonstrate cost-effectiveness if pseudarthrosis and reoperation rates are decreased, thus avoiding subsequent expenditure. METHODS: This was a retrospective cohort study of patients who underwent instrumented lumbar fusions utilizing rhBMP-2. Hospital finance records were used to calculate direct total expenditure incurred by the primary payer for the procedure using rhBMP-2. For patients who received rhBMP-2 in a secondary lumbar fusion, additional total expenditure related to the patients' failed primary instrumented fusion with ICBG was also sought. RESULTS: The mean total costs associated with failed instrumented lumbar fusion using ICBG and reoperation using rhBMP-2 totaled £47,734 per patient. The total direct costs of a policy of primary instrumented lumbar fusion with rhBMP-2 were less at £26,923 per patient; however, this was not significant. CONCLUSIONS: To date, this is the first study to report the costs of failed primary instrumented lumbar fusions using ICBG and subsequent secondary fusions using rhBMP-2 from a primary payer perspective. On the basis of this evidence, a policy of using rhBMP-2 in all patients undergoing a primary instrumented lumbar fusion cannot be recommended.

Optic neuropathy secondary to eosinophilic angiocentric fibrosis.

Eosinophilic angiocentric fibrosis (EAF) is a rare fibroinflammatory disorder with a predilection for upper respiratory tract submucosa. We report a 45-year-old man with progressive unilateral visual loss secondary to a retroorbital soft tissue mass with histological features consistent with EAF. The patient experienced marked improvement in vision after endoscopic optic nerve decompression through sphenoethmoidectomy.