The T1 Pelvic Angle (TPA), a Novel Radiographic Parameter of Sagittal Deformity, Correlates Strongly with Clinical Measures of Disability

https://doi.org/10.1016/j.spinee.2013.07.173Get rights and content

Section snippets

Background Context

The importance of the sagittal plane in adult spinal deformity (ASD) has been well demonstrated in the literature. Established measures of sagittal balance such as the sagittal vertical axis (SVA), T1 spinopelvic inclination (T1SPi), and the pelvic tilt (PT) can be modified by postural compensation, including pelvic retroversion and knee flexion, and by factors affecting patient positioning as in the use of patient assistive devices and patient support in standing. We introduce the T1 pelvic

Purpose

To investigate the relationship of the TPA and other established radiographic measures of sagittal alignment and to correlate these parameters with clinical measures of disability.

Study Design/Setting

Multicenter, prospective database.

Patient Sample

Consecutive case series.

Outcome Measures

Oswestry Disability Index (ODI), Scoliosis Research Society (SRS)-22, and Short-Form (SF)-36 Physical Component Score (PCS).

Methods

Multicenter, prospective, analysis of consecutive ASD patients. Inclusion criteria: ASD, age>18, and any of the following: scoliosis Cobb angle greater than 20°, SVA greater than 5 cm, thoracic kyphosis greater than 60°, and PT greater than 25 deg. Clinical measures of disability included ODI, SRS and SF36.

Results

559 consecutive ASD patients (mean age 52.5) were enrolled. TPA correlated most strongly with SVA (r=0.837) and PI-LL (r=0.889) and PT (0.933). Categorizing the patients by increasing TPA (<10; 10-20; 20-30; >30) revealed a significant and progressive worsening in HRQOL (all p<0.001). T1PA and SVA correlated strongly with ODI (0.435, 0.457), SF36 PCS (-0.440, -0.465) and SRS (-0.304, -0.360). Utilizing a linear regression analysis, the threshold for TPA of 19.8 was found to correspond to a

Conclusions

The TPA correlates strongly with HRQOL in patients with ASD. The TPA is related to both PT and SVA, but unlike SVA, it does not vary based on the extent of pelvic retroversion or patient support in standing. Thus T1PA measures sagittal deformity independent of many postural compensatory mechanisms. It is also possible to measure the TPA on a prone intraoperative long-cassette radiograph to gauge global correction, a function which is not possible with SVA, PT or T1SPi. Since the TPA is an

FDA Device/Drug Status

This abstract does not discuss or include any applicable devices or drugs.

References (0)

Cited by (0)

View full text