The 301 operative classification for ankylosing spondylitis kyphosis

English Keywords:Ankylosing spondylitis  Kyphosis  Classification

English Abstract:

  【Abstract】 Objectives: To design a new classification(301 operative classification) for ankylosing spondylistis(AS) kyphosis, and to identify the inter-observer and intra-observer reliability and repeatability. Methods: AS kyphosis was divided into 4 types according to the location of the apex: lumbar(type Ⅰ), thoracolumbar(type Ⅱ), thoracic (type Ⅲ), and cervical or cervicothoracic junction kyphosis(type Ⅳ), and each type except type Ⅰ has 2 subtypes: with lumbar lordosis(A) and with lumbar kyphosis(B). The total consecutive 309 patients suffering from AS kyphosis deformity undergoing a spinal osteotomy in our hospital were reviewed. The common type, each type′s frequencies were determined. Five spine surgeons independently assigned the curve type to 30 patients following the guidance described by new classification. The procedure was repeated two weeks later with the same patients presented in different order. Kappa value was used to determine the intra-observer and inter-observer repeatability and reliability. Results: There were 4 types and 7 subtypes for AS kyphosis according to 301 classification. Among the 309 patients, 52(16.8%) patients were type Ⅰ, 223(72.2%) type Ⅱ, 33(10.7%) type Ⅲ and 1(0.3%) type Ⅳ. The thoracolumbar type(type Ⅱ) was the most common. The inter-observer reliability testing was from 73.3% to 86.7%(Kappa coefficient was 0.761-0.847), while intra-observer repeatability was 83.3%-93.3%(Kappa coefficient was 0.821-0.925). Conclusions: This new classification system can be used easily and conveniently to classify AS kyphosis with good reliability and repeatability.