What Should an Ideal Adult Spinal Deformity Classification System Consist of?: Review of the Factors Affecting Outcomes of Adult Spinal Deformity Management

Abstract

This literature review aims to determine potential clinical factors or comorbidities besides radiological parameters that affect the outcome of adult spinal deformity (ASD) management and review existing classifications associated with ASD. ASD is a multifactorial disease that comprises pathologies like radiological spine deformity, coexistence of spinal canal stenosis, radiculopathy, and multiple comorbidities. The available classification systems of ASD are predominantly based on radiological parameters and do not consider related clinical conditions. ASD patients with different combinations of these parameters behave differently and need different management strategies. We conducted a narrative literature review with search limited to English language of PubMed/MEDLINE using Medical Subject Heading (MeSH) terms. The terms specific to the review were ASD and several other related terminologies. We analyzed the information of the selected papers including factors affecting surgical outcomes for degenerative scoliosis. We reviewed 614 citations. Based on the inclusion criteria, 39 citations were selected for full-text retrieval; of these, 28 were excluded because of not fulfilling the inclusion criteria. Thus, 11 studies were selected and included for the final analysis. The presence of leg pain, spinal stenosis, obesity, osteoporosis, smoking, and age of patients were major influencing factors. Furthermore, the factors included in the available classifications, such as the Scoliosis Research Society–Schwab classifications, were reviewed and results were tabulated. This review highlights the significance of neurological symptoms, spinal stenosis, osteoporosis, obesity, age, and smoking, which markedly affect the management of ASD. With increasing number of patients being diagnosed and treated with ASD, there has been a growing need to comprehensively classify these patients into clinicoradiological subgroups.

Adult Spinal Deformity: Current Concepts and Decision-Making Strategies for Management

“…In 2005, Aebi [18] proposed a classification system based on etiology that is uniquely helpful in understanding the natural history of ASD. However, Bess et al [16] proposed a new classification system that was based on "high-impact, clinically significant radiographic parameters" through a prospective study that investigated the clinical outcomes [17,19,20]. In 2012, the Scoliosis Research Society (SRS) Adult Deformity Committee revised the previously proposed system in order to include the pelvic parameters owing to substantial correlations with health-related quality of life (HRQoL) [17,19].…”

“…However, Bess et al [16] proposed a new classification system that was based on "high-impact, clinically significant radiographic parameters" through a prospective study that investigated the clinical outcomes [17,19,20]. In 2012, the Scoliosis Research Society (SRS) Adult Deformity Committee revised the previously proposed system in order to include the pelvic parameters owing to substantial correlations with health-related quality of life (HRQoL) [17,19]. Currently, the SRS-Schwab adult spine deformity classification is considered the standard system because all of its modifiers include spinopelvic parameters and owing to a strong correlation with the HRQoL scores [1,16].…”

“…These criteria apply to curves >30°. The modifiers include type T (thoracic only; thoracic major curve >30° at the apical level of T9 or higher), type L (TL/lumbar only; isolated thoracolumbar or lumbar curve >30° at the apical level of T10 or lower), type D (double major curve with thoracic and thoracolumbar/lumbar curve >30°), and type N (normal; no definite coronal deformity) [16][17][18][19].…”

“…If PT is <20°, the modifier is "0"; if the degree is 20°-30°, the modifier is "+"; if the degree is >30°, the modifier is "++. " Increases in PT correlate to pain and disability [16][17][18][19][20].…”

Bracing Adult Scoliosis: From Immobilization to Correction of Adult Scoliosis

“…The radiological risk factors for instability are (1) rotatory dislocation with lateral olisthesis (Figure 1), (2) L3-L4 inclination, (3) hypolordosis, and (4) increased thoracolumbar kyphosis [19][20].…”